JP2017062192A - Linear expansion coefficient measurement method and measurement apparatus for dimension reference device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear expansion coefficient measurement method and measurement apparatus for a dimension reference device capable of highly accurately and inexpensively measuring a linear expansion coefficient for dimension reference devices of various lengths.SOLUTION: A measurement object (step gauge 10) and a reference gauge (reference block gauge 20) are supported in parallel inside of a thermostat 30. While setting an internal temperature of the thermostat 30 at a first temperature and defining a length from a first reference surface 21 to a second reference surface 22 of the reference gauge as a reference, a length from a first surface 11 to a second surface 12 of the measurement object is comparatively measured. While defining the internal temperature of the thermostat 30 at a second temperature and similarly defining the length from the first reference surface 21 to the second reference surface 22 as a reference, the length from the first surface 11 to the second surface 12 is comparatively measured. A linear expansion coefficient of the measurement object is calculated from the length of the measurement object at the first temperature and the length of the measurement object at the second temperature.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a linear expansion coefficient measuring method and measuring apparatus for a dimension reference device.

In a measuring apparatus such as a three-dimensional measuring machine, a dimension reference device is used for inspection.
As the dimension reference device, various block gauges whose end face dimensions are calibrated with high accuracy are used, and step gauges corresponding to a plurality of lengths are used.
The step gauge has a comb-like shape in which convex portions and concave portions are alternately arranged, and a plurality of reference dimensions are obtained between the end surfaces of the convex portions. Such a step gauge is manufactured by alternately arranging measurement blocks to be convex portions and interval blocks to be concave portions and fixing them to a holder, and by cutting out from a single member into a comb shape. Manufactured.

The calibration value of the distance between the end faces of the step gauge is provided as a length at a specific temperature, often the length at the industry standard temperature at 20 ° C.
In the inspection of the CMM, the measured length must be converted into the temperature at the time of calibration. This is generally referred to as length temperature correction. At this time, it is necessary to accurately know the linear expansion coefficient of the step gauge.

Many dimensional reference devices including step gauges have a linear expansion coefficient used for temperature correction in a calibration certificate or inspection report. Such linear expansion coefficients are each displayed with a tolerance.
When a step gauge is used for inspection of a CMM, this tolerance is treated as an uncertainty factor in examining the inspection uncertainty. Therefore, it is required to evaluate the linear expansion coefficient of the step gauge with high accuracy in order to reduce the uncertainty in the inspection.

The linear expansion coefficient of the object including the dimension reference device is obtained by changing the temperature of the object and measuring the amount of change in the length of the object due to the temperature change.
Specifically, the linear expansion coefficient α is defined as Lo for the length of the object at the reference temperature To, L for the length of the object at the current temperature T, the amount of temperature change ΔT = T−To, the amount of change in the length (thermal expansion). The quantity is given by α = (ΔL / L) · (1 / ΔT) as ΔL = L−Lo.

In a dimension reference device such as a step gauge, the size of the length L of the object is larger than the fifth power of 10 with respect to the change amount ΔL of the length. For this reason, generally, the accuracy of the numerical value of the length L has little influence on the numerical value of the linear expansion coefficient α.
Therefore, in order to obtain the linear expansion coefficient α with high accuracy, it is necessary to measure the temperature change ΔT and the length change ΔL with high accuracy.

In order to measure such a linear expansion coefficient α, a measurement method using a light wave interferometer has been proposed (see Patent Document 1).
In Patent Document 1, two sets of light wave interferometers facing each other on the same measurement axis are used so that the length between both end faces of an object to be measured such as a block gauge can be measured with high accuracy. Then, the temperature of the object to be measured is changed by the temperature control means, the length is measured at different temperatures, the amount of thermal expansion due to the temperature change is acquired, and the linear expansion coefficient is calculated.

  However, the length measurement using such a light wave interferometer has a problem that the light wave interferometer is expensive. In other words, not only is the optical interferometer itself expensive, but also the calculation of the refractive index of air is necessary to correct the wavelength of the light for measurement, and this includes the environment such as temperature, humidity, atmospheric pressure, and carbon dioxide concentration. A measuring machine is also necessary, and there is a problem that the entire system becomes expensive.

  Further, in the length measurement using the light wave interferometer, since the reflected light from both end faces of the object to be measured is used, the length to be measured is limited to the length of the measurement object. That is, there is a problem that it is difficult to apply to a reference device having a comb-like measurement surface such as a step gauge to measure the length of the convex portions of the intermediate portion.

  In order to solve such a problem, a method using a three-dimensional measuring machine (see Patent Document 2) and a method using a clip portion and a strain gauge (see Patent Document 3) have been proposed.

In the method of Patent Document 2, a step gauge as an object to be measured is placed in a thermostat, an external CMM probe is introduced from the opening of the thermostat, and the length of the step gauge is measured by this probe. To do. And the temperature setting in a thermostat is changed, length measurement is performed at different temperature, and the amount of thermal expansion is calculated from the difference in measurement length before and after temperature change.
In length measurement using such a three-dimensional measuring machine, it is not necessary to use a light wave interferometer, and an environment where a general-purpose three-dimensional measuring machine can be used is sufficient.
Moreover, by using a three-dimensional measuring machine, the length between the convex parts of the intermediate part of a step gauge can also be measured, and the uniformity of the thermal expansion coefficient of the intermediate part can also be measured.

In the method of Patent Document 3, a sandwiching part sandwiching an arbitrary convex part of a step gauge is used, a strain gauge is installed on one of the chips that contacts the step gauge of the sandwiching part, and a pair of end faces for measuring the length are sandwiched between them. The temperature is changed while sandwiched between the parts, and the thermal expansion accompanying the temperature change is directly detected by a strain gauge.
In the measurement of thermal expansion using such a sandwiching portion and a strain gauge, it is not necessary to use a light wave interferometer, and a simple and inexpensive configuration of the sandwiching portion and the strain gauge may be used. Length measurements can also be made.

Japanese Patent No. 3897655 JP 2004-226369 A JP 2005-83920 A

By the way, a dimensional reference device such as a step gauge is used in various dimensions according to the size of the CMM to be inspected. For example, a long step gauge may have a nominal dimension (nominal length) exceeding 1.5 m.
The above-described measurement of the linear expansion coefficient α of the dimension reference device is required to be applicable to such a dimension reference device having a large length L and to be measured with high accuracy.

However, the method of Patent Document 3 described above has a problem that the measurement length is fixed by the sandwiching portion, and various measurements such as the length of the intermediate portion cannot be performed. In addition, for a long step gauge, it is necessary to prepare a pinch portion of an appropriate size, which restricts implementation.
Furthermore, since a noise component is included in the output of the strain gauge, there is a problem that it is difficult to extract only the linear expansion coefficient of the step gauge from the amount converted into the length.

  On the other hand, if a three-dimensional measuring machine is used for length measurement as in Patent Document 2 described above, the length between both end faces and the convex portion of the intermediate portion with respect to the dimensional reference device of various lengths. It is possible to cope with various measurements such as the length between the end faces of each other, and the linear expansion coefficient can be measured based on the measurement at different temperatures.

However, even when length measurement by a three-dimensional measuring machine is used as in the method of Patent Document 2, there is a possibility that problems such as a decrease in accuracy may occur for the above-described large step gauge having a length exceeding 1.5 m. .
That is, the maximum allowable length measurement error is used as an index indicating the measurement performance of the coordinate measuring machine. The maximum allowable length measurement error is generally given by a linear expression and increases in proportion to the measurement length. This means that the accuracy decreases as the length to be measured increases. For this reason, it is difficult to measure the linear expansion coefficient with high accuracy for a long step gauge.

  An object of the present invention is to provide a linear expansion coefficient measuring method and a measuring apparatus for a linear reference coefficient that can measure the linear expansion coefficient with high accuracy and at low cost for various length reference instruments.

  The linear expansion coefficient measuring method of the dimension reference device according to the present invention uses the dimension reference device as a measurement object, and the line of the portion from the first surface to the second surface of the measurement object that is separated in the extending direction of the measurement object. A linear expansion coefficient measuring method for a dimension reference device for measuring an expansion coefficient, the first reference surface and the second reference surface corresponding to the first surface and the second surface, and from the first reference surface A reference gauge whose length to the second reference surface is known, a thermostatic chamber capable of accommodating the measurement object and the reference gauge, adjustable in internal temperature, and having a measurement opening on the measurement surface; A measurement object support that is installed inside the thermostat and supports the measurement object, a reference gauge support that is installed inside the thermostat and supports the reference gauge, and the measurement opening The measurement process inside the thermostat A coordinate measuring machine capable of introducing a probe, supporting the measurement object and the reference gauge in parallel inside the thermostat, and setting the internal temperature of the thermostat as the first temperature. The length from the first surface to the second surface is compared and measured based on the length from the first reference surface to the second reference surface, and the internal temperature of the thermostat is set to the second temperature, Using the length from the first reference surface to the second reference surface as a reference, the length from the first surface to the second surface is comparatively measured, and the first surface at the first temperature is A linear expansion coefficient of the measurement object is calculated from a length up to two surfaces and a length from the first surface to the second surface at the second temperature.

In the present invention, since the length of the measurement object is measured using a three-dimensional measuring machine, the linear expansion coefficient of the dimensional reference device having various lengths can be increased without using an expensive optical interferometer. It can be measured with high accuracy.
At this time, the length from the first surface to the second surface can be measured as the length of the measurement object. For this reason, the length of a measuring object and the linear expansion coefficient between them can be measured by making the both end surfaces of a measuring object into the 1st surface and the 2nd surface. Moreover, the length and linear expansion coefficient of this intermediate part can also be measured by setting the 1st surface and the 2nd surface to the end surface of the convex part of the intermediate part of a measuring object.

  Furthermore, in this invention, when measuring the length of a measuring object using a three-dimensional measuring machine, a reference gauge is used as a reference for the length, and a comparative measurement of the length with respect to this reference gauge is performed. For this reason, the result of the length measurement does not depend on the accuracy of the scale of the coordinate measuring machine, but exclusively depends on the accuracy of the reference gauge, and high accuracy can be ensured even if the measuring object is elongated.

That is, in the present invention, in the comparative measurement of length, when the measurement object is short, a short reference gauge corresponding to the measurement object is used, and when the measurement object is long, according to this. Use a long reference gauge.
Then, the length of the reference gauge (distance between the first reference surface and the second reference surface) and the length of the measurement object (distance between the first surface and the second surface) are measured by a three-dimensional measuring machine, The difference between the measurement length of the reference gauge and the measurement length of the measurement object is added to the reference length known for the reference gauge, thereby calculating the length of the measurement object.
That is, the CMM measures the difference between the measurement length of the reference gauge and the measurement length of the measurement object, specifically the distance between the first surface and the first reference surface, and the second surface and the second reference surface. It is only necessary to measure the distance.
For this reason, in the present invention, even if the measurement object is long in the comparative measurement of length, it is not affected by the maximum allowable length measurement error which is the measurement performance of the coordinate measuring machine.

  As described above, according to the method for measuring the linear expansion coefficient of the dimension reference device of the present invention, the measurement of the linear expansion coefficient of the dimension reference device of various lengths can be performed with high accuracy and at low cost.

  In the linear expansion coefficient measuring method of the dimension reference device of the present invention, when performing the comparative measurement, calculation of center coordinates of the first reference surface, the second reference surface, the first surface, and the second surface; It is desirable to perform a coordinate system determination including calculation of an inclination of the reference gauge and the measurement object with respect to the extending direction.

In the present invention as described above, when performing comparative measurement, it is possible to determine a coordinate system serving as a reference for measuring each length of the reference gauge and the measurement object.
That is, even if the first reference surface and the second reference surface of the reference gauge and the first surface and the second surface of the measurement object are inclined with respect to the stretching direction, the contact of the CMM on each surface The detection position by the coordinate measuring machine can be corrected from the distance from the position to the center coordinate and the inclination of each surface.
Then, each coordinate system is determined according to the current state of the reference gauge and the object to be measured, and the accuracy can be improved by measuring the length under the coordinate system. Can be kept high.

In the method for measuring a linear expansion coefficient of a dimension reference device according to the present invention, it is preferable that the reference gauge support base supports the reference gauge on a side of the measurement object facing the measurement opening.
The side of the measurement object that faces the measurement opening can be, for example, the upper surface side or the side surface side of the measurement object.

  In the present invention as described above, the first surface and the second surface, which are the measurement target portions of the measurement object, are arranged on the measurement opening side, and the reference gauge is arranged on the same side, whereby the first reference of the comparison target The surface and the second reference surface can be arranged close to the first surface and the second surface, and the measurement accuracy can be improved and the measurement operation can be made more efficient and faster.

In the method for measuring a linear expansion coefficient of a dimension reference device according to the present invention, it is desirable that the reference gauge has a length in the extension direction shorter than the measurement object by a predetermined length.
The predetermined length is such that the area on the measurement opening side of the measurement object that can be contacted by the probe of the coordinate measuring machine is close to the first surface or the second surface. Any length is acceptable. For example, when a step gauge having a plurality of convex portions is used as the measurement object, the reference gauge may be shorter than the length of the step gauge by one convex portion.

In this invention, since the reference gauge is arranged on the measurement opening side of the measurement object, the surface of the measurement object on the measurement opening side is covered with the reference gauge. However, in the vicinity of the end portion of the measurement object, the surface is exposed to the measurement opening side because the length of the reference gauge is short.
Therefore, in the coordinate system determination described above, the surface can be detected without interfering with the reference gauge by bringing the probe of the coordinate measuring machine into contact with the exposed surface of the end of the measurement object.

  In the method for measuring a linear expansion coefficient of a dimensional reference device according to the present invention, when the comparative measurement is performed, the first reference surface and the first surface are arranged in the same plane, or the second reference surface and the first surface are measured. It is desirable to arrange the two surfaces in the same plane.

  In the present invention, when the reference gauge is made shorter than the measurement object by a predetermined length as described above, the length of the reference gauge and the measurement object at the end opposite to the same plane side. The difference in height is maximized, and the margin when performing surface detection by the probe of the coordinate measuring machine can be maximized.

  In the method for measuring a linear expansion coefficient of a dimensional reference device according to the present invention, the measurement object support base includes a measurement object first support base and a measurement object second support base, and the measurement object first support base and the measurement target object support base The measurement object second support base regulates the displacement of the measurement object in two directions intersecting with the extending direction and rotates the measurement object with the two directions intersecting the extending direction as a central axis. Allow, one of the measurement object first support base and the measurement object second support base regulates the displacement of the measurement object in the stretching direction, and the other is the measurement object in the stretching direction One of the measurement object first support base and the measurement object second support base regulates rotation of the measurement object with the extending direction as a central axis, and either The other is centered on the stretching direction The measurement object is allowed to rotate, and the reference gauge support base includes a reference gauge first support base and a reference gauge second support base, and the reference gauge first support base and the reference gauge second support base. Restricts the displacement of the reference gauge in two directions intersecting the extending direction, and allows the reference gauge to rotate about the two directions intersecting the extending direction as a central axis. One of the base and the second support base of the reference gauge regulates the displacement of the reference gauge in the extending direction and the other allows the displacement of the reference gauge in the extending direction, and the first support of the reference gauge Either the base or the second reference gauge second support base regulates the rotation of the reference gauge with the extending direction as the central axis, and the other has the extending direction as the central axis. It is desirable to permit rotation of the quasi-gauge.

In the present invention as described above, the measurement object and the reference gauge are regulated (positioned) on one side of the first and second supports with respect to the displacement in the extending direction, and the displacement is allowed on the other side. By doing so, the comparative measurement of the length of the measuring object and the reference gauge in the extending direction can be accurately performed. Further, either one of the first and second supports is bent to the measurement object and the reference gauge by restricting the rotation about the extending direction as the central axis and allowing the rotation around the other axis. Even if deformation occurs, this can be allowed.
In the present invention, such a measurement object support base and a reference gauge support base can cope with free expansion and change in posture of the measurement object and the reference gauge, and the measurement object and the reference gauge can be extended in each extending direction. It is possible to maintain the desired state parallel to each other.

  In the method for measuring a linear expansion coefficient of a dimensional reference device according to the present invention, the first object to be measured is between a contact portion between a conical hole and a sphere and a contact between a plane and the sphere between the bottom surface of the measurement object. Any one or two of the contact portions between the V-groove and the sphere, and the measurement object second support base is between the conical hole and the sphere between the bottom surface of the measurement object. It is desirable to have a contact portion that is not on the first object support base among the contact portion, the contact portion between the flat surface and the sphere, and the contact portion between the V groove and the sphere.

  In the present invention, the measurement object support base including the measurement object first support base and the measurement object second support base is a contact portion between the conical hole and the sphere between the bottom surface of the measurement object, A kinematic mount having three points, that is, a contact portion between a plane and a sphere and a contact portion between a V groove and a sphere, can be configured, and the above-described displacement restriction and rotation restriction with respect to the extending direction and the intersecting direction are appropriately performed. be able to.

  In the method for measuring a linear expansion coefficient of a dimensional reference device according to the present invention, the first object to be measured is between a contact portion between a conical hole and a sphere and a contact between a plane and the sphere between the bottom surface of the measurement object. The measurement object second support base is between the contact portion between the conical hole and the sphere and the contact portion between the plane and the sphere between the bottom surface of the measurement object. The measurement object has a contact portion that is not on the first support base, and either the measurement object first support base or the measurement target object second support base is formed between one side surface of the measurement target object and a sphere. It is desirable to have a contact part and a pressing means for pressing the side surface of the measurement object against the sphere.

  In such a present invention, in either the measurement object first support base or the measurement object second support base, the combination of the contact portion with the side surface of the measurement object and the pressing means allows displacement in the stretching direction. However, in order to restrict the displacement in the two directions intersecting the stretching direction, a function corresponding to a combination of a V groove and a sphere formed on the bottom surface of the measurement object is performed. As a result, in the measurement object first support base and the measurement object second support base, a function corresponding to the kinematic mount described above can be obtained, and the displacement restriction and rotation restriction described above with respect to the extending direction and the crossing direction thereof. Can be performed appropriately.

  In the method for measuring a linear expansion coefficient of a dimensional reference device according to the present invention, the reference gauge first support is between a contact portion between a conical hole and a sphere, a contact portion between a plane and a sphere, between the bottom surface of the reference gauge, Any one or two of the contact portions between the V-groove and the sphere are provided, and the reference gauge second support is between the bottom surface of the reference gauge and the contact portion between the conical hole and the sphere, a flat surface. It is desirable to have a contact portion that is not in the reference gauge first support among the contact portion between the sphere and the sphere and the contact portion between the V groove and the sphere.

  In the present invention as described above, the reference gauge support base including the reference gauge first support base and the reference gauge second support base includes a contact portion between the conical hole and the sphere, a plane and the sphere between the bottom face of the reference gauge. The kinematic mount having the three contact points, that is, the contact portion between the V groove and the sphere, can be configured, and the above-described displacement restriction and rotation restriction with respect to the extending direction and the crossing direction can be appropriately performed.

  In the method of measuring a linear expansion coefficient of a dimensional reference device according to the present invention, the reference gauge first support base has a conical hole-sphere contact portion, a plane-sphere contact portion, and a bottom surface of the reference gauge. The reference gauge second support is between the bottom surface of the reference gauge and the reference gauge second of the contact portion between the conical hole and the sphere and the contact portion between the plane and the sphere. 1 has a contact portion not on the support base, and either the reference gauge first support base or the reference gauge second support base has a contact portion between one side surface of the reference gauge and a sphere, and the reference gauge It is desirable to have a pressing means for pressing the side surface against the sphere.

  In such a present invention, in either the reference gauge first support base or the reference gauge second support base, the combination of the side face of the reference gauge and the pressing means intersects the extending direction while allowing displacement in the extending direction. In order to regulate displacement in two directions, a function corresponding to a combination of a V groove and a sphere formed on the bottom surface of the reference gauge is performed. As a result, in the reference gauge first support base and the reference gauge second support base, a function equivalent to the kinematic mount described above can be obtained, and the displacement restriction and rotation restriction described above with respect to the extending direction and the crossing direction are appropriately performed. Can be done.

  In the method for measuring a linear expansion coefficient of a dimensional reference device according to the present invention, a support adapter that is attached to the reference gauge and supported by the reference gauge support base, or a support adapter that is attached to the measurement object and attached to the measurement object support base. It is desirable to use a supported adapter that is supported.

  In the present invention, even when the above-described kinematic mount or the like is supported, it is only necessary to form a conical hole or a V-groove in the support adapter, and it is not necessary to form directly on the reference gauge or the measurement object. Can be made easier.

  In the method for measuring a linear expansion coefficient of a dimensional reference device according to the present invention, it is desirable to have pressurizing means for pressurizing the reference gauge downward.

In the present invention as described above, even when the reference gauge is light, it is possible to stably support the reference gauge support by applying pressure downward.
Note that the measurement object generally has a larger weight than the reference gauge, and no pressurization is required. However, when the measurement object is light, similar pressurization may be performed.

  In the present invention, the reference gauge is manufactured from a material having an extremely low expansion coefficient or a zero expansion coefficient that can be accurately ignored in the temperature change between the first temperature and the second temperature, or It is desirable that the material is manufactured from a material having a known expansion coefficient.

In the present invention, when the reference gauge is manufactured from a material having an extremely low expansion coefficient or zero expansion coefficient, temperature correction of the length of the reference gauge between the first temperature and the second temperature is omitted. can do. On the other hand, when the reference gauge is manufactured from a material having a known expansion coefficient, the length of the reference gauge with high accuracy at each temperature can be calculated by temperature correction at the first temperature and the second temperature. In any case, since the reference gauge length at each temperature can be made accurate, the comparative measurement at the first temperature and the comparative measurement at the second temperature can be performed with high accuracy.
As such a reference gauge, an existing block gauge with high accuracy can be used.

  The linear expansion coefficient measuring apparatus for a dimensional reference device according to the present invention uses a dimensional reference device as a measurement object, and is a line of a portion from the first surface to the second surface of the measurement object that is separated in the extending direction of the measurement object. A linear expansion coefficient measuring device for a dimensional reference device for measuring an expansion coefficient, comprising a first reference surface and a second reference surface corresponding to the first surface and the second surface, and from the first reference surface A reference gauge whose length to the second reference surface is known, a thermostatic chamber capable of accommodating the measurement object and the reference gauge, adjustable in internal temperature, and having a measurement opening on the measurement surface; A measurement object support that is installed inside the thermostat and supports the measurement object, a reference gauge support that is installed inside the thermostat and supports the reference gauge, and the measurement opening The measurement process inside the thermostat It characterized by having a a coordinate measuring machine capable of introducing over drive.

  In the present invention as described above, a similar effect can be obtained by the procedure as described in the method for measuring the linear expansion coefficient of the dimension reference device of the present invention described above.

  ADVANTAGE OF THE INVENTION According to this invention, the linear expansion coefficient measuring method and measuring apparatus of a dimension reference device which can measure a linear expansion coefficient with high precision and low cost with respect to the dimension reference device of various length can be provided.

The perspective view which shows the measuring apparatus of 1st Embodiment of this invention. The perspective view which shows the step gauge which is a measuring object of the said 1st Embodiment. The perspective view which shows the reference | standard block gauge which is the reference | standard gauge of the said 1st Embodiment. The perspective view which shows arrangement | positioning of the thermostat of the said 1st Embodiment, a step gauge, and a reference | standard block gauge. The side view which shows the measurement object 1st support stand of the said 1st Embodiment. The side view which shows the measurement object 2nd support stand of the said 1st Embodiment. The side view which shows the reference | standard gauge 1st support stand of the said 1st Embodiment. The side view which shows the reference gauge 2nd support stand of the said 1st Embodiment. The perspective view which shows the bottom face side of the reference | standard block gauge of the said 1st Embodiment. The flowchart which shows the measurement procedure of the said 1st Embodiment. The side view which shows the installation state of the said 1st Embodiment. The perspective view which shows the measurement operation | movement of the said 1st Embodiment. The perspective view which shows the support adapter of 2nd Embodiment of this invention. The perspective view which shows the thermostat of 3rd Embodiment of this invention. The perspective view which shows arrangement | positioning of the thermostat of the said 3rd Embodiment, a step gauge, and a reference | standard block gauge. The side view which shows the measurement object 1st support stand of 4th Embodiment of this invention. The side view which shows the measurement object 2nd support stand of the said 4th Embodiment. The side view which shows the reference | standard gauge 1st support stand of 5th Embodiment of this invention. The side view which shows the reference gauge 2nd support stand of the said 5th Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
In FIG. 1, a linear expansion coefficient measuring apparatus 1 according to this embodiment uses a step gauge 10 as a dimension reference device as a measurement object, and measures the linear expansion coefficient with high accuracy.
For this purpose, the linear expansion coefficient measuring apparatus 1 includes a thermostat 30 that houses the step gauge 10 and maintains the step gauge 10, a reference block gauge 20 as a reference gauge that is also housed in the thermostat 30, and a reference block gauge And a three-dimensional measuring machine 40 for comparing and measuring the length of the step gauge 10 with reference to 20.

The three-dimensional measuring machine 40 has a surface plate 41, and a head 44 is supported on the upper surface thereof by a column 42 and a cross bar 43. The head 44 is provided with a ram 45 extending downward, and a probe 46 is supported at the tip thereof.
In the coordinate measuring machine 40, the column 42 is movable in the Y-axis direction with respect to the surface plate 41, the head 44 is movable in the X-axis direction with respect to the cross bar 43, and the ram 45 is moved with respect to the head 44. Thus, it is movable in the Z-axis direction. By these three-axis movements, the probe 46 can be three-dimensionally moved with respect to the surface plate 41.

The thermostat 30 is a device that can maintain the temperature inside the box-shaped housing at a desired temperature, is placed on the upper surface of the surface plate 41, and is fixed so that its longitudinal direction is along the Y-axis direction. .
The thermostatic chamber 30 can accommodate the step gauge 10 and the reference block gauge 20 inside by opening and closing the upper surface side.
A plurality of measurement openings 31 having an openable / closable lid are formed on the upper surface of the thermostat 30.

  Inside the thermostatic chamber 30, the step gauge 10 is supported so that the extending direction Lt is along the Y-axis direction. The reference block gauge 20 is disposed on the upper surface side of the step gauge 10 (side facing the measurement opening 31 of the step gauge 10), and the extending direction Lr thereof is parallel to the step gauge 10 along the Y-axis direction. It is supported by.

As shown in FIG. 2, the step gauge 10 as the measurement object has a prismatic main body extending in the extending direction Lt, and the upper surface, the bottom surface, and each side surface are two directions that intersect the extending direction Lt. It is parallel to either the direction Ht or the width direction Wt.
A plurality of block gauge-like convex portions 13 are arranged on the upper surface of the step gauge 10 in the extending direction Lt. The length of each protrusion 13 in the extending direction Lt is Dp, and the distance between the protrusions 13 in the extending direction Lt between the protrusions 13 is Dc.
In the present embodiment, the surface of the convex portion 13 at one end of the step gauge 10 is the first surface 11, and the surface of the convex portion 13 at the other end is the second surface 12, and these first surfaces 11 and the second surface 12 are measured as the length Dx of the step gauge 10.

As shown in FIG. 3, the reference block gauge 20 that is a reference gauge is a block gauge that extends in the extending direction Lr, and has an upper surface, a bottom surface, and each side surface in a height direction Hr that is two directions intersecting the extending direction Lr and It is parallel to one of the width directions Wr.
The reference block gauge 20 has a pair of end faces corresponding to both ends in the extending direction Lr as a first reference surface 21 and a second reference surface 22.

In the reference block gauge 20, the distance between the first reference surface 21 and the second reference surface 22, that is, the length is Drx. The reference block gauge 20 is based on the length Dx (nominal dimension, nominal dimension) of the measurement target in the step gauge 10 that is the measurement target, and the length Drx is a predetermined dimension (for example, the length of the convex portion 13) than the length Dx. (Dp)) A short dimension is selected.
The reference block gauge 20 not only has a known length Drx but also has a known linear expansion coefficient with high accuracy, and is used for comparative measurement at a first temperature t1 and comparative measurement at a second temperature t2, which will be described later. Can calculate the length Drx at each temperature t1, t2 with high accuracy from the linear expansion coefficient.

In FIG. 4, the step gauge 10 and the reference block gauge 20 are installed in parallel in the thermostatic bath 30.
In order to support the step gauge 10 and the reference block gauge 20, a highly rigid bottom plate 32 is installed in the thermostat 30, and a measurement object support base 50 and a reference gauge support base 60 are installed on the upper surface thereof. ing.

The measurement object support 50 includes a measurement object first support 51 on the first surface 11 side and a measurement object second support 52 on the second surface 12 side.
The reference gauge support 60 is composed of a reference gauge first support 61 on the first reference surface 21 side and a reference gauge second support 62 on the second reference surface 22 side.

[Measurement Object First Support 51]
In FIG. 5, the measurement object first support base 51 has a base portion 511 installed on the bottom plate 32, and standing portions 512 and 513 are formed along both side edges. The step gauge 10 is accommodated in a space between the upright portions 512 and 513 and supported on the base portion 511.
On the base 511, two sets of balls 514 and a ball holder 515 are arranged side by side in the width direction Wt. The ball holder 515 has a large number of support balls that roll on the ball 514 and forms a so-called free ball bearing or ball caster.

The bottom surface of the step gauge 10 is brought into contact with two balls 514, and these balls 514 and the ball holder 515 allow a flat surface and a sphere to be interposed between the measurement object first support 51 and the bottom surface of the step gauge 10. A contact portion 502 is formed.
The load of the step gauge 10 is supported by the thermostat 30 through the base 511 and the bottom plate 32 by these two sets of contact portions 502.

In the contact portion 502, the bottom surface of the step gauge 10 and the ball 514 roll so that the step gauge 10 can be displaced in the extending direction Lt and the width direction Wt, and the height direction H and the width direction Wt are the central axes. Rotation (yawing and pitching) is possible.
However, the bottom surface of the step gauge 10 and the ball 514 are in contact with each other, and displacement in the height direction Ht is restricted. Further, since there are two pairs of balls 514, rotation (rolling) with the extending direction Lt as the central axis is also restricted.

Between the standing part 512 and the side surface of the step gauge 10, a ball 514 and a ball holder 515 similar to the contact part 502 between the base part 511 and the contact part 504 between the plane and the sphere are formed. ing.
A ball 514 and a ball holder 515 similar to the contact portion 502 between the upright portion 513 and the side surface of the step gauge 10 are installed. Further, a compression coil spring 516 is installed between the ball holder 515 and the upright portion 513. These balls 514, ball holder 515, and compression coil spring 516 form a pressing means 505.

  The step gauge 10 is pressed along the width direction Wt by the pressing means 505, is pressed against the upright portion 512 via the contact portion 504, and the displacement is restricted in the width direction Wt. However, since the pressing means 505 and the contact portion 504 come into contact with the side surface of the step gauge 10 via the ball 514, the displacement in other directions is not restricted, and the rotation around each direction is restricted. Nor.

Therefore, in the measurement object first support base 51, the displacement along the height direction Ht of the step gauge 10 is regulated while the load of the step gauge 10 is supported by the two sets of contact portions 502. Further, the displacement along the width direction Wt of the step gauge 10 is also restricted by the contact portion 504 and the pressing means 505, thereby determining the direction of the step gauge 10 in the extending direction Lt.
On the other hand, in the measurement object first support base 51, displacement in the stretching direction Lt is allowed, pitching and yawing are allowed, and when the step gauge 10 is thermally deformed, expansion and contraction in the stretching direction Lt is allowed. can do.

[Measurement object second support base 52]
In FIG. 6, the measurement object second support base 52 includes a base portion 521 installed on the bottom plate 32 and a support portion 522 on which the lower surface of the step gauge 10 is placed.
A ball 524 and a ball holder 525 are installed on the base 521. The ball holder 525 has a large number of support balls that roll on the ball 524 and forms a so-called free ball bearing or ball caster.

A conical hole 529 is formed on the lower surface of the support portion 522, and the ball 524 is fitted in the conical hole 529.
The conical hole 529 and the ball 524 form a contact portion 501 between the conical hole and the sphere.

  Therefore, in the measurement object second support base 52, while the load of the step gauge 10 is supported by the contact portion 501, the displacement of the step gauge 10 in the height direction Ht, the displacement in the width direction Wt, and the displacement in the extending direction Lt. All are regulated. However, in the contact portion 501, rotation around the ball 524 with the height direction Ht as the central axis (yawing), rotation with the width direction Wt as the central axis (pitching), and rotation with the extending direction Lt as the central axis All (rolling) is allowed.

As described above, the step gauge 10 is supported by the measurement object first support base 51 and the measurement object second support base 52.
Thereby, the step gauge 10 is regulated in the position in the width direction Wt in each of the measurement object first support base 51 and the measurement object second support base 52, and the extending direction Lt is the thermostat 30 and the three-dimensional measuring machine 40. Are supported so as to be aligned in the Y-axis direction.
And although the position of the extending direction Lt is restrained in the contact part 501 of the measuring object 2nd support stand 52, in the measuring object 1st support stand 51, the displacement of the extending direction Lt is accept | permitted, and expansion-contraction by a thermal deformation is carried out. Appears mainly on the first surface 11 side.

[Reference gauge first support 61]
In FIG. 7, the reference gauge first support base 61 includes a base 611 disposed above the bottom plate 32 and a column 612 fixed to the lower surface of the base 611, and is supported on the bottom plate 32 by the column 612. .
On the base 611, two sets of balls 614 and a ball holder 615 are installed side by side in the width direction Wr. The ball holder 515 has a large number of support balls that roll on the ball 514 and forms a so-called free ball bearing or ball caster.

Of the two sets of balls 614 and the ball holder 615, one set of balls 614 is brought into contact with the lower surface of the reference block gauge 20, thereby forming a contact portion 602 between the plane and the sphere.
Of the two sets of balls 614 and the ball holder 615, the other set of balls 614 is fitted into a conical hole 619 (see FIG. 9) formed in the lower surface of the reference block gauge 20, thereby A contact portion 601 is formed.

  Therefore, in the reference gauge first support base 61, the load of the reference block gauge 20 is supported by the contact portion 602 between the plane and the sphere aligned in the width direction Wr and the contact portion 601 between the conical hole and the sphere, Displacement in the height direction Hr, displacement in the width direction Wr, displacement in the stretching direction Lr, and rotation (rolling) with the stretching direction Lr as the central axis are restricted, and rotation (yawing) and width with the height direction Hr as the central axis Rotation (pitching) with the direction Wr as the central axis is allowed.

Further, a standing portion 610 is formed in the base portion 611, and between the standing portion 610 and the upper surface of the reference block gauge 20, a ball 614 and a ball holder 615 similar to the contact portion 602, and these are connected to the reference block gauge 20. A compression coil spring 617 that is urged toward the upper surface is installed, thereby forming a pressurizing means 609 that pressurizes the reference block gauge 20 downward.
By such a pressurizing means 609, in the reference gauge first support base 61, even when the weight of the reference block gauge 20 is small, the contact of the contact portions 601 and 602 on the lower surface side is reliably maintained.

[Reference gauge second support stand 62]
In FIG. 8, the reference gauge second support base 62 includes a base 621, a column 622, and an upright part 620 similar to the reference gauge first support base 61. The ball 624, the ball holder 625, and the compression coil spring 627 constitute a similar pressurizing unit 609.
On the other hand, in the reference gauge second support base 62, instead of the contact portion 602 between the plane and the sphere and the contact portion 601 between the conical hole and the sphere in the reference gauge first support base 61, a contact portion between the V groove and the sphere. 603 is configured.

  A ball 624 and a ball holder 625 are installed on the upper surface of the base 621. A V-groove 628 is formed along the extending direction Lr on the lower surface of the opposing reference block gauge 20 (see FIG. 9). By fitting the ball 624 into the V groove 628, a contact portion 603 between the V groove and the ball is formed.

  Therefore, in the reference gauge second support table 62, the load of the reference block gauge 20 is supported by the contact portion 603 between the V groove and the ball, and the displacement in the height direction Hr and the displacement in the width direction Wr are regulated. Displacement in the stretching direction Lr, rotation around the stretching direction Lr (rolling), rotation around the height direction Hr (yawing), and rotation around the width direction Wr (pitching) are allowed. Yes.

As described above, the reference block gauge 20 is supported by the reference gauge first support base 61 and the reference gauge second support base 62.
Thereby, the reference block gauge 20 is regulated in the position in the width direction Wr in each of the reference gauge first support base 61 and the reference gauge second support base 62, and the extending direction Lr is the constant temperature bath 30 and the coordinate measuring machine 40. It is supported so as to be aligned in the Y-axis direction (that is, the extending direction Lt of the step gauge 10).
The position in the extending direction Lr is constrained at the contact portion 601 of the reference gauge first support 61, but the displacement in the extending direction Lr is allowed in the reference gauge second support 62, and expansion and contraction due to thermal deformation is mainly performed. Appear on the first reference surface 21 side.

[Measurement of linear expansion coefficient]
FIG. 10 shows a procedure for measuring the linear expansion coefficient of the step gauge 10 using the linear expansion coefficient measuring apparatus 1.
In starting the measurement, first, the thermostat 30 is fixed to the three-dimensional measuring device 40 as the linear expansion coefficient measuring apparatus 1, and the step gauge 10 and the reference block gauge 20 are installed inside the thermostat 30 (processing S1).

  When installing the step gauge 10 and the reference block gauge 20 inside the thermostat 30, first, the measurement object first support base 51 and the measurement object second support base 52 are installed, and the step gauge 10 is thereby installed. To support. Next, the reference gauge first support base 61 and the reference gauge second support base 62 are installed so as to straddle the step gauge 10, and the reference block gauge 20 is supported by these.

As shown in FIG. 11, when the step gauge 10 and the reference block gauge 20 are installed, the positions of the extending directions Lt and Lr are adjusted so that the second surface 12 and the second reference surface 22 are the same. Keep it flat.
Here, since the length Drx of the reference block gauge 20 is set shorter than the length Dx of the step gauge 10 by the length Dx of the convex portion 13, the second reference surface 22 and the second surface 12 are aligned. In this case, the first reference surface 21 does not reach the first surface 11 by the length Dx of the convex portion 13, and the convex portion 13 closest to the first surface 11 is not covered with the reference block gauge 20 on the upper surface side. State.

When the step gauge 10 and the reference block gauge 20 are installed (process S1), the measurement length (the length Dx of the step gauge 10) is input to the coordinate measuring machine 40 (process S2), and the step gauges at different temperatures are input. A comparative measurement operation with a length of 10 is executed (steps S3 to S5).
First, with all the measurement openings 31 closed, the internal temperature of the thermostatic chamber 30 is set to the first temperature t1, and the temperature is stabilized after waiting for a predetermined time (process S3).

When the inside of the thermostat 30 is stabilized at the first temperature t1, the coordinate systems of the step gauge 10 and the reference block gauge 20 are determined (processing S4).
Specifically, the measurement opening 31 on the first surface 11 side is opened, and the probe 46 of the coordinate measuring machine 40 is introduced. Then, as shown in FIG. 12, the first surface 11 of the step gauge 10 is contacted with three or more points to detect the position and inclination. Furthermore, about the upper surface and one side surface of the convex part 13 in which the 1st surface 11 was set, 3 points or more are similarly contacted, and a position and inclination are detected. Thereby, the three-dimensional coordinates of the center position of the first surface 11 and the direction of the extending direction Lt of the step gauge 10 are acquired.

Similarly, the probe 46 detects the contact between the first reference surface 21 of the reference block gauge 20 and the adjacent upper and side surfaces, and the three-dimensional coordinates of the center position of the first reference surface 21 and the extending direction of the reference block gauge 20. Get the direction of Lr.
Further, the probe 46 is introduced through the measurement opening 31 on the second surface 12 side, the second surface 12 of the step gauge 10 and the second reference surface 22 of the reference block gauge 20 are measured, and the second surface 12 and the second surface 12 are measured. The three-dimensional coordinates of the center position of the reference surface 22 are acquired.

When the coordinate systems of the step gauge 10 and the reference block gauge 20 are determined (process S4), the dimensions of the step gauge 10 and the reference block gauge 20 are compared and measured, and the temperature at that time is measured and recorded (process). S5).
Specifically, the distance between the center position of the first surface 11 and the center position of the first reference surface 21, the center position of the second surface 12, and the center of the second reference surface 22 under the coordinate system by the process S 4. Based on the distance between the first surface 11 and the second surface 12 by calculating from the distance between the first reference surface 21 and the second reference surface 22 (length Drx of the reference block gauge 20). The distance (exact value of the length Dx) can be measured by comparison.

As described above, when the comparative measurement of the distance between the first surface 11 and the second surface 12 at the first temperature t1 is completed, the internal temperature of the thermostatic bath 30 is changed to the second temperature t2 (processing S6), and the comparison described above. The measurement operation (processing S3 to S5) is repeated.
As a result, the length Dx1 at the first temperature t1 and the length Dx2 at the second temperature t2 are obtained, so that the length D of the step gauge 10 is the first surface 11 and the second surface of the step gauge 10. 12 can be calculated as linear expansion coefficient α = [(Dx1−Dx2) / D] / (t1−t2) (step S7). The length D may be either the measured length Dx1, the length Dx2, or an average value, and may be the nominal length of the step gauge 10. In either case, thermal deformation ΔD = (Dx1 Since it is sufficiently large with respect to -Dx2), it does not affect the calculation of the linear expansion coefficient α.

[Effects of First Embodiment]
According to this embodiment, the following effects can be obtained.
Since the length of the step gauge 10 which is a measurement object is measured using the three-dimensional measuring machine 40, the linear expansion coefficient of the step gauge 10 of various lengths can be obtained with high accuracy without using an expensive optical interferometer. Can be measured.

  Furthermore, in this embodiment, when measuring the length of the step gauge 10 using the coordinate measuring machine 40, the reference block gauge 20 is used as a reference for the length, and the comparative measurement of the length with respect to the reference block gauge 20 is performed. I do. For this reason, the result of the length measurement does not depend on the accuracy of the scale of the coordinate measuring machine 40, but depends exclusively on the accuracy of the reference block gauge 20. Even if the step gauge 10 is elongated, high accuracy can be obtained. It can be secured.

In the present embodiment, calculation of the center coordinates of the first reference surface 21, the second reference surface 22, the first surface 11 and the second surface 12 and the extension of the reference block gauge 20 and the step gauge 10 are performed when performing comparative measurement. The coordinate system determination including the calculation of the inclination with respect to the directions Lr and Lt (processing S4 in FIG. 11) is performed.
Therefore, even if the first reference surface 21 and the second reference surface 22 of the reference block gauge 20 and the first surface 11 and the second surface 12 of the step gauge 10 are inclined with respect to the stretching directions Lr and Lt. The detection position by the coordinate measuring machine 40 can be corrected from the distance from the contact position of the probe 46 on each surface to the center coordinates and the inclination of each surface.
Then, each coordinate system is determined according to the current state of the reference block gauge 20 and the step gauge 10, and the length is measured under the coordinate system, so that the accuracy can be improved. High accuracy can be maintained.

  In the present embodiment, the first surface 11 and the second surface 12 that are measurement target portions of the step gauge 10 are arranged on the measurement opening 31 side, and the reference block gauge 20 is arranged on the same side, so The first reference surface 21 and the second reference surface 22 can be arranged close to the first surface 11 and the second surface 12, and the measurement accuracy can be improved and the measurement operation can be made more efficient and faster.

In the present embodiment, the length Drx from the first reference surface 21 to the second reference surface 22 of the reference block gauge 20 is more convex than the length Dx from the first surface 11 to the second surface 12 of the step gauge 10. A length Dp corresponding to one part 13 was set to be short.
For this reason, even if the reference block gauge 20 is disposed on the measurement opening 31 side of the step gauge 10 and the surface of the step gauge 10 is covered with the reference block gauge 20, the reference block gauge 20 is near the end on the first surface 11 side. Since the length of the block gauge 20 is short, the surface of the step gauge 10 is exposed to the measurement opening 31 side. Therefore, in determining the coordinate system described above, the surface of the step gauge 10 can be detected without interfering with the reference block gauge 20 by bringing the probe 46 of the coordinate measuring machine 40 into contact with the exposed surface. it can.

  In the present embodiment, since the second reference surface 22 and the second surface 12 are arranged in the same plane, when the reference block gauge 20 is made shorter than the step gauge 10 by a predetermined length as described above, the same plane is used. The difference in length between the reference block gauge 20 and the step gauge 10 is maximized at the opposite end (the first surface 11 and the first reference surface 21 side) of the three-dimensional measuring instrument 40. The margin when performing surface detection by the probe 46 can be maximized.

  In the present embodiment, in the measurement object first support base 51, the combination of the contact portion 504 with the side surface of the step gauge 10 and the pressing means 505 intersects the stretching direction Lt while allowing displacement in the stretching direction Lt. In order to restrict displacement in the direction (height direction Ht, width direction Wt), this combination provides a function corresponding to the combination of the V-groove and sphere of the kinematic mount. As a result, in the measurement object first support base 51 and the measurement object second support base 52, a function corresponding to a kinematic mount can be obtained, and displacement regulation and rotation regulation with respect to the extending direction Lt and its intersecting direction can be performed. Can be done appropriately.

  In this embodiment, the reference gauge first support base 61 and the reference gauge second support base 62 constitute a reference gauge support base 60, and a conical hole and sphere contact portion 601 between the bottom surface of the reference block gauge 20. A kinematic mount having three points of a contact portion 602 between a plane and a sphere and a contact portion 603 between a V groove and a sphere can be formed, and an extending direction Lr and its intersecting direction (height direction Hr, width direction Wr ) Can be appropriately controlled.

  In the present embodiment, the pressurizing means 609 that pressurizes the reference block gauge 20 downward is provided. Therefore, even when the reference block gauge 20 is lightweight, by applying the downward pressure, the reference gauge first support base 61 and the reference block The support by the gauge 2nd support stand 62 can be performed stably.

In addition, this embodiment can each respond | correspond also when measuring the length between the convex parts 13 of the intermediate part of the step gauge 10, when the length of the step gauge 10 is shorter.
In FIG. 11, when setting the length of the intermediate portion of the step gauge 10, the first surface 11 is set on the convex portion 13 of the intermediate portion, and the reference block gauge 20 having a corresponding length is set, as shown by a one-dot chain line. The first reference surface 21 may be set using the probe 46 and each measurement may be performed with the probe 46. At this time, when the probe 46 is introduced into the thermostat 30, the nearest one of the plurality of measurement openings 31 may be used.

[Second Embodiment]
FIG. 13 shows a second embodiment of the present invention.
In the first embodiment described above, when the reference block gauge 20 is supported by the reference gauge first support base 61 and the reference gauge second support base 62, the conical hole 619 and the V groove 628 are directly formed on the lower surface of the reference block gauge 20. Formed.

On the other hand, in 2nd Embodiment, as shown in FIG. 13, the support adapters 71 and 72 are attached to the reference | standard block gauge 20, and the conical hole 619 and the V groove 628 are formed in each lower surface.
Note that the configuration of the second embodiment is the same as that of the first embodiment except for the support portion of the reference block gauge 20, and therefore, a duplicate description is omitted, and only different portions will be described below.

The support adapter 71 is installed at a position supported by the reference gauge first support base 61 of the reference block gauge 20. The support adapter 71 has a support plate 711 and a fixing member 712, and is fixed to the reference block gauge 20 by sandwiching the reference block gauge 20 in each.
The support adapter 72 is installed at a position supported by the reference gauge second support 62 of the reference block gauge 20. The support adapter 72 has a support plate 721 and a fixing member 722, and is fixed to the reference block gauge 20 by sandwiching the reference block gauge 20 in each.

A conical hole 619 is formed on the lower surface of the support plate 711, and a V-groove 628 is formed on the lower surface of the support plate 711.
Using these, between the support adapters 71 and 72 and the reference gauge first support base 61 and the reference gauge second support base 62, the lower surface of the reference block gauge 20 of the first embodiment (see FIG. 9). Similarly, a contact portion 601 between the conical hole and the sphere, a contact portion 602 between the plane and the sphere, and a contact portion 603 with the V groove are formed.

In this embodiment, the effects of the first embodiment described above can be obtained without forming the conical hole 619 and the V groove 628 on the lower surface of the reference block gauge 20.
Since it is not necessary to form the conical hole 619 and the V-shaped groove 628 on the lower surface of the reference block gauge 20, a common one can be used as the reference block gauge 20 by sharing the support adapters 71 and 72. It can be easily handled.

[Third Embodiment]
14 and 15 show a third embodiment of the present invention.
In the first embodiment described above, the measurement opening 31 for introducing the probe 46 is formed on the upper surface of the constant temperature bath 30, and inside the constant temperature bath 30, the upper surface side of the step gauge 10 (the side where the measurement opening 31 is present). The reference block gauge 20 is arranged in parallel on the same side with the convex portion 13 facing the surface.

On the other hand, in 3rd Embodiment, as shown in FIG.14 and FIG.15, the measurement opening 31A for introducing the probe 46 is formed in the side surface of the thermostat 30A, and the step gauge 10 is made along the same side surface. The reference block gauge 20 is arranged in parallel between the side surface and the step gauge 10.
Also in this embodiment, the same effect as that of the first embodiment described above can be obtained.

[Fourth Embodiment]
16 and 17 show a fourth embodiment of the present invention.
In the first embodiment described above, two contact portions 502 between a flat surface and a sphere are formed between the measurement object first support base 51 (see FIG. 5) and the lower surface of the step gauge 10, and the step gauge 10 is formed. The pressing means 505 and the contact portion 504 are formed so as to be sandwiched from the side. Further, in the measurement object second support base 52 (see FIG. 6), a conical hole-sphere contact portion 501 is formed between the lower surface of the step gauge 10.

On the other hand, in the fourth embodiment, in the measurement object first support base 51A (see FIG. 16), the contact portion 502 between the plane and the sphere and the contact between the conical hole and the sphere between the lower surface of the step gauge 10. A portion 501 (conical hole 519) is formed, and a contact portion 503 (V groove 528) between the V groove and the sphere is formed between the measurement object second support base 52A (see FIG. 17) and the lower surface of the step gauge 10. Forming.
In this embodiment, a configuration corresponding to a kinematic mount can be formed between the step gauge 10, the measurement object first support base 51A, and the measurement object second support base 52A.

  A conical hole and sphere contact portion 501 is formed between the measurement object first support base 51A and the step gauge 10, and a plane and a sphere are formed between the measurement object second support base 52A and the step gauge 10. The contact portion 502 and the contact portion 503 between the V groove and the sphere may be formed.

[Fifth Embodiment]
18 and 19 show a fifth embodiment of the present invention.
In the first embodiment described above, in the reference gauge first support base 61 (see FIG. 7), the conical hole / sphere contact portion 601 and the flat surface / sphere contact portion 602 between the lower surface of the reference block gauge 20. Further, in the reference gauge second support base 62 (see FIG. 8), a contact portion 603 between the V groove and the sphere is formed between the lower surface of the reference block gauge 20.

On the other hand, in the fifth embodiment, in the reference gauge first support base 61A (see FIG. 18), two contact portions 602 between the plane and the sphere are formed between the lower surface of the reference block gauge 20 and the reference block. Pressing means 605 (ball 614, ball holder 615, compression coil spring 616) and contact portion 604 (ball 614, ball holder 615) are formed so as to sandwich the gauge 20 from the side. Further, in the reference gauge second support base 62A (see FIG. 19), a conical hole-sphere contact portion 601 (conical hole 629) is formed between the lower surface of the reference block gauge 20.
Also in this embodiment, a configuration corresponding to a kinematic mount can be formed between the reference block gauge 20, the reference gauge first support base 61A, and the reference gauge second support base 62A.

  In addition, a contact portion 603 between a V groove and a sphere and a contact portion 602 between a plane and a sphere are formed between the reference gauge first support base 61A and the reference block gauge 20, and the reference gauge second support base 62A and the reference block are formed. A contact portion 601 between the gauge 20 and the conical hole and the sphere may be formed.

[Modification]
The present invention is not limited to the configuration of each of the embodiments described above, and modifications and the like within a scope in which the object of the present invention can be achieved are included in the present invention.
For example, in each embodiment, in the reference gauge first support bases 61 and 61A and the reference gauge second support bases 62 and 62A, the pressurizing unit 609 reliably maintains the contact of the contact portions 601, 602, and 603 on the lower surface side. I was supposed to be.
Such a pressurizing unit 609 is not limited to a mechanical unit using the compression coil springs 617 and 627 but may be a non-contact energizing unit utilizing fluid pressure, fluid flow, electromagnetic force, or the like. Good.
Further, the pressurizing means 609 may be omitted if the weight of the reference block gauge 20 is sufficient.

  In the first embodiment described above, the length Dx from the first surface 11 to the second surface 12 is measured as the length of the step gauge 10. However, the length of the step gauge 10 and the linear expansion coefficient therebetween can be measured by setting both end faces of the step gauge 10 to the first surface 11 and the second surface 12. Further, as described with reference to FIG. 10, the length and the linear expansion coefficient of the intermediate portion are measured by setting the first surface 11 and the second surface 12 to the end face of the convex portion 13 of the intermediate portion of the step gauge 10. You can also

In each of the above-described embodiments, the step gauge 10 is the measurement object. However, the measurement object may be a block gauge or another dimension reference device.
Further, the reference gauge is not limited to the reference block gauge 20, and a master gauge that is a dedicated reference gauge or a step gauge 10 similar to the measurement object and calibrated with high accuracy may be used.
At this time, the reference gauge is manufactured from a material having an extremely low expansion coefficient or zero expansion coefficient that can be ignored in terms of accuracy when the temperature changes between the first temperature t1 and the second temperature t2, or the expansion of the reference gauge. It is desirable to be one made from a material with a known coefficient.

In the embodiment, the second reference surface 22 of the reference block gauge 20 that is the reference gauge and the second surface 12 of the step gauge 10 that is the measurement object are aligned on the same plane, but the first reference surface 21 and the first surface are the same. The surface 11 may be aligned, or the reference gauge and the measurement object may not be aligned at both ends.
However, by aligning either end, the difference in length between the reference gauge and the object to be measured is maximized at the end opposite to the same plane. The margin when performing detection can be maximized.

  INDUSTRIAL APPLICABILITY The present invention can be used for a linear expansion coefficient measuring method and measuring apparatus for a dimensional reference device.

  DESCRIPTION OF SYMBOLS 1 ... Linear expansion coefficient measuring apparatus, 10 ... Step gauge which is a measuring object, 11 ... 1st surface, 12 ... 2nd surface, 13 ... Convex part, 20 ... Reference block gauge which is a reference gauge, 21 ... 1st reference | standard Surface 22 ... Second reference surface 30, 30A ... Thermostatic bath 31 ... Measurement opening 31A ... Measurement opening 32 ... Bottom plate 40 ... Three-dimensional measuring machine 41 ... Surface plate 42 ... Column 43 ... Cross bar, 44 ... head, 45 ... ram, 46 ... probe, 50 ... measurement object support base, 501 ... conical hole and sphere contact portion, 502 ... plane and sphere contact portion, 503 ... V groove and sphere 504 ... contact portion between the flat surface and the sphere, 505 ... pressing means, 51 and 51A ... first object support base, 511 ... base, 512 ... standing portion, 513 ... standing portion, 514 ... ball, 515 ... Ball holder, 516 ... Compression coil spring, DESCRIPTION OF SYMBOLS 19 ... Conical hole, 52, 52A ... Measurement object 2nd support stand, 521 ... Base, 522 ... Support part, 524 ... Ball, 525 ... Ball holder, 528 ... V groove, 529 ... Conical hole, 60 ... Reference gauge support 601: Contact portion between conical hole and sphere, 602 ... Contact portion between plane and sphere, 603 ... Contact portion between V groove and sphere, 604 ... Contact portion between plane and sphere, 605 ... Pressing means, 609 ... pressurizing means, 61, 61A ... reference gauge first support, 610 ... standing part, 611 ... base, 612 ... strut, 614 ... ball, 615 ... ball holder, 616 ... compression coil spring, 617 ... compression coil spring, 619 ... Conical hole 62, 62A ... Reference gauge second support, 620 ... Standing part, 621 ... Base, 622 ... Post, 624 ... Ball, 625 ... Ball holder, 628 ... V groove, 629 ... Conical hole, 71, 72 ... Holding adapter, 711, 721 ... support plate, 712, 722 ... fixing member, Dx ... length of measurement object, Drx ... length of reference gauge, Hr ... height direction of reference gauge, Ht ... height of measurement object Direction, Lr ... reference gauge extension direction, Lt ... measurement object extension direction, T ... temperature, t1 ... first temperature, t2 ... second temperature, To ... reference temperature, Wr ... reference gauge width direction, Wt ... the width direction of the measurement object, α ... linear expansion coefficient, ΔL ... the amount of change in length.

Claims (14)

Method of measuring linear expansion coefficient of dimension reference device, measuring linear expansion coefficient of portion from first surface to second surface of measurement object separated in extending direction of measurement object, using dimension reference device as measurement object Because
A reference gauge having a first reference surface and a second reference surface corresponding to the first surface and the second surface and having a known length from the first reference surface to the second reference surface;
A thermostatic chamber that can accommodate the measurement object and the reference gauge, can adjust the internal temperature, and has a measurement opening on the measurement surface;
A measurement object support that is installed inside the thermostat and supports the measurement object;
A reference gauge support that is installed inside the thermostat and supports the reference gauge;
A three-dimensional measuring machine capable of introducing a measurement probe from the measurement opening into the thermostat;
Prepare
Inside the thermostat, the measurement object and the reference gauge are supported in parallel,
The internal temperature of the thermostat is set as the first temperature, and the length from the first surface to the second surface is compared and measured based on the length from the first reference surface to the second reference surface.
The internal temperature of the thermostat is set as the second temperature, and the length from the first surface to the second surface is compared and measured based on the length from the first reference surface to the second reference surface.
The linear expansion coefficient of the measurement object is calculated from the length from the first surface to the second surface at the first temperature and the length from the first surface to the second surface at the second temperature. A method for measuring a linear expansion coefficient of a dimensional reference device. In the linear expansion coefficient measuring method of the dimension reference device according to claim 1,
When performing the comparative measurement, calculation of the center coordinates of the first reference surface, the second reference surface, the first surface and the second surface, and the inclination of the reference gauge and the measurement object with respect to the extending direction And a linear expansion coefficient measurement method for a dimension reference device, characterized in that a coordinate system determination is performed. In the linear expansion coefficient measuring method of the dimension reference device according to claim 2,
The method for measuring a linear expansion coefficient of a dimensional reference device, wherein the reference gauge support base supports the reference gauge on a side of the measurement object facing the measurement opening. In the linear expansion coefficient measuring method of the dimension reference device according to claim 3,
The method for measuring a linear expansion coefficient of a dimension reference device, wherein the reference gauge has a length in the extending direction shorter than the measurement object by a predetermined length. In the linear expansion coefficient measuring method of the dimension reference | standard device described in Claim 4,
When the comparative measurement is performed, the first reference surface and the first surface are arranged in the same plane, or the second reference surface and the second surface are arranged in the same plane. To measure the linear expansion coefficient of a dimensional standard. In the linear expansion coefficient measuring method of the dimension reference | standard device as described in any one of Claims 1-5,
The measurement object support table includes a measurement object first support table and a measurement object second support table,
The measurement object first support base and the measurement object second support base each regulate the displacement of the measurement object in two directions intersecting with the extending direction and center the two directions intersecting with the extending direction. Allowing the measurement object to rotate,
One of the measurement object first support base and the measurement object second support base regulates the displacement of the measurement object in the extending direction, and the other one displaces the measurement object in the extending direction. Allow
Either one of the first object to be measured and the second object to be measured supports the rotation of the object to be measured with the extending direction as a central axis, and the other is centered on the extending direction. While allowing rotation of the measurement object as an axis,
The reference gauge support includes a reference gauge first support and a reference gauge second support,
The reference gauge first support base and the reference gauge second support base each regulate the displacement of the reference gauge in two directions intersecting the extending direction and have the two directions intersecting the extending direction as a central axis. Allow the reference gauge to rotate,
One of the reference gauge first support base and the reference gauge second support base regulates the displacement of the reference gauge in the extending direction, and the other allows the displacement of the reference gauge in the extending direction,
One of the reference gauge first support base and the reference gauge second support base regulates the rotation of the reference gauge with the extending direction as a central axis, and either one has the extending direction as a central axis. A method for measuring a linear expansion coefficient of a dimension reference device, wherein the reference gauge is allowed to rotate. In the linear expansion coefficient measuring method of the dimension reference device according to claim 6,
The measurement object first support base is one of a contact portion between a conical hole and a sphere, a contact portion between a flat surface and a sphere, and a contact portion between a V groove and a sphere between the bottom surface of the measurement object. Have one or two,
The measurement object second support is between the bottom surface of the measurement object and the measurement part among a contact portion between a conical hole and a sphere, a contact portion between a plane and a sphere, and a contact portion between a V groove and a sphere. A linear expansion coefficient measuring method for a dimensional reference device, comprising a contact portion that is not on the first support of the object. In the linear expansion coefficient measuring method of the dimension reference device according to claim 6,
The measurement object first support base has any one of a contact portion between a conical hole and a sphere and a contact portion between a plane and a sphere between the bottom surface of the measurement object,
The measurement object second support base is not in contact with the measurement object first support base among the contact part between the conical hole and the sphere and the contact part between the flat surface and the sphere between the bottom surface of the measurement object. Part
Either the measurement object first support base or the measurement object second support base presses the contact portion between one side surface of the measurement object and the sphere and the side surface of the measurement object against the sphere. And a linear expansion coefficient measuring method for a dimensional reference device. In the linear expansion coefficient measuring method of the dimension reference device according to any one of claims 6 to 8,
The reference gauge first support base is any one of a contact portion between a conical hole and a sphere, a contact portion between a plane and a sphere, and a contact portion between a V groove and a sphere between the bottom surface of the reference gauge. Or have two,
The reference gauge second support is between the bottom surface of the reference gauge and the reference gauge first of the contact portion between the conical hole and the sphere, the contact portion between the flat surface and the sphere, and the contact portion between the V groove and the sphere. 1. A linear expansion coefficient measuring method for a dimensional reference device, comprising a contact portion not on a support base. In the linear expansion coefficient measuring method of the dimension reference device according to any one of claims 6 to 8,
The reference gauge first support base has any one of a contact portion between a conical hole and a sphere and a contact portion between a plane and a sphere between the bottom surface of the reference gauge,
The reference gauge second support base has a contact portion between the conical hole and the sphere and a contact portion that is not on the reference gauge first support base among the contact portions between the flat hole and the sphere, between the bottom surface of the reference gauge. And
Either the reference gauge first support base or the reference gauge second support base includes a contact portion between one side surface of the reference gauge and a sphere, and a pressing unit that presses the side surface of the reference gauge against the sphere. A linear expansion coefficient measuring method for a dimensional standard device, comprising: In the linear expansion coefficient measuring method of the dimension reference device according to any one of claims 1 to 10,
A dimensional standard using a support adapter attached to the reference gauge and supported by the reference gauge support base, or a support adapter attached to the measurement object and supported by the measurement object support base. For measuring the linear expansion coefficient of a vessel. In the linear expansion coefficient measuring method of the dimension reference device according to any one of claims 1 to 11,
A linear expansion coefficient measuring method for a dimension reference device, comprising pressurizing means for pressurizing the reference gauge downward. In the linear expansion coefficient measuring method of the dimensional standard device according to any one of claims 1 to 12,
The reference gauge is manufactured from a material having an extremely low expansion coefficient or a zero expansion coefficient that can be ignored in terms of accuracy when the temperature changes between the first temperature and the second temperature, or the expansion coefficient is known. A method for measuring a linear expansion coefficient of a dimension reference device, wherein the linear expansion coefficient is manufactured from a material which is A linear expansion coefficient measuring device for a dimension reference device that measures a linear expansion coefficient of a portion from the first surface to the second surface of the measurement object that is separated in the extending direction of the measurement object, using the dimension reference device as a measurement object. Because
A reference gauge having a first reference surface and a second reference surface corresponding to the first surface and the second surface and having a known length from the first reference surface to the second reference surface;
A thermostatic chamber that can accommodate the measurement object and the reference gauge, can adjust the internal temperature, and has a measurement opening on the measurement surface;
A measurement object support that is installed inside the thermostat and supports the measurement object;
A reference gauge support that is installed inside the thermostat and supports the reference gauge;
A three-dimensional measuring machine capable of introducing a measurement probe from the measurement opening into the thermostat;
A linear expansion coefficient measuring device for a dimensional reference device, characterized by comprising:

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