JP2000322115A - Numerical controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To actualize high-speed, high-precision curve machining by making corrections with a correction quantity which in nearly proportional to the corresponding axial components of acceleration according to relative values of partial elastic deformation such as the mass and elasticity or deformation quantity, etc., of a movable body which moves together with a support member in parallel to the axis. SOLUTION: An acceleration arithmetic part 123 calculates the acceleration between interpolation points from the coordinates of the interpolation points found by an interpolative arithmetic part 122. A correction quantity arithmetic part 124 inputs the x-axial component and y-axial component of the acceleration of a tool between the interpolation points on a machining curve and finds the x-axial elastic deformation quantity and y-axial elastic deformation quantity at each interpolation point on the machining curve. An addition arithmetic part 125 corrects the position command values at each interpolation point into coordinate values with the coordinates of the interpolation points on the machining curve inputted from the interpolative arithmetic part 122 and the x-axial elastic deformation quantities and y-axial elastic deformation quantities at the interpolation points inputted from the correction quantity arithmetic part 124. This corrected position command value is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a numerical control device for a machine tool, and more particularly, to a numerical control device for preventing the occurrence of a machining shape error due to a partial elastic deformation of a machine tool system which occurs during high-speed machining. About.

[0002]

2. Description of the Related Art In the field of machine tools such as machining centers, high-speed or high-acceleration machine tools, for example, by adopting a linear motor drive or reducing the weight of a movable body, for the purpose of shortening the machining time for a workpiece. Has been proposed and developed. With these technological innovations, a high acceleration (1 G or more) which cannot be realized by a conventional machine tool using a ball screw drive, a cast iron column, or the like has been achieved.

[0003]

When a moving body (a support member such as a tool) constituting a part of a machine tool system is accelerated or decelerated, an inertial force proportional to the mass and acceleration acts on the moving body. Due to the action of this inertial force, a partial elastic deformation occurs in the machine tool system, and in particular, control points such as a tool tip,
If this elastic deformation occurs between a positioning point for detecting the position of the tool and the moving body composed of a support member or the like, the positioning accuracy with respect to the control point deteriorates when the moving body including the support member is accelerated or decelerated.

[0004] Such a problem is particularly caused by the fact that the rigidity of the components is relatively low due to the weight reduction of the movable body or the like, or a machine tool capable of high-speed machining by driving a linear motor or the like has been manufactured. Since then, it has been surfaced or revealed. In addition, such a shape error increases as the speed or acceleration of the moving body during processing increases.

The present invention has been made to solve the above problems, and an object thereof is to realize high-speed, high-precision curve machining.

[0006]

In order to solve the above-mentioned problems, the following means are effective. That is, a first means is a numerical controller for moving a support member, which supports a supported object made of a tool or a workpiece, at a high speed along a machining curve of the workpiece, wherein the machine tool is driven by acceleration of the support member or the like. A movable body that moves in parallel with the planned acceleration of the support member and the support member for each axis component of the control axis, the deviation of the movement path of the support member from the processing curve caused by the partial elastic deformation of the system. And a position command value corrector that corrects with a correction amount substantially proportional to the corresponding axis component of the acceleration based on the relevant value of the partial elastic deformation such as the mass and the elastic modulus or the deformation amount.

[0007] The second means may be a tool or a workpiece.
The supporting member for supporting the object to be supported is moved in the first axial direction.
A first movable body movably supported, and the first movable body
Moveable in a second axis direction orthogonal to the first axis direction
A second movable body to be supported is controlled so that the supporting member is
Numerical control unit for high-speed movement along the machining curve
First movable by the acceleration (a) of the supported object
Path of support member movement caused by partial elastic deformation of body
The deviation from the machining curve of
Speed (a_y) And mass m of the support member and the first movable body_y
And the elastic modulus of the first movable body (K_y) And related value
(C_y), A first axial component of the acceleration a
(A_y), The correction amount (ε_y)
In addition, partial elastic deformation of the second movable body due to acceleration (a)
Of the movement path of the support member caused by
To the acceleration acting in the second axis direction (a_x)
Mass of holding member, first movable body and second movable body
(M_x) And the elastic modulus of the second movable body (K _x)
Related value (C_x), The direction of the second axis of the acceleration a
Directional component (a_x), The correction amount (ε_x)
That is, a position correcting means is provided.

A third means is that the related values (C _x, C _y ) are experimentally obtained in advance in the second means.

Further, the fourth means is the second or third means.
Means (a) acting in the first axial direction
_y) and acceleration acting on said second axial (a _x)
Is calculated from the NC data for instructing the movement route of the support member.

Further, the fifth means includes the first to fourth means.
In any one of the means, at least one of the support member and each of the movable bodies is driven by a linear motor. With the above means, the above-mentioned problem can be solved.

[0011]

[Effects and Effects of the Invention] For simplification of the functions and effects of the present invention, a case of curved processing on the xy plane will be described below. If the inertial force and the shape error during the processing are expressed as (F _x , F _y ) and (ε _x , ε _y ) for each of the x-axis component and the y-axis component, the following equations (1) to (8) ) Holds. However, the definitions of other variables are as follows. (Variable definition) a: magnitude of acceleration of support member θ: angle of acceleration of support member in curved coordinate display (direction of acceleration) ε: magnitude of shape error a _x : x-axis component of acceleration of support member 2: axial component) _mx : mass of the movable body that moves in parallel with the support member in the x-axis direction (mass of the support member, the first movable body, and the second movable body) K _x : the shape error ε _x modulus a _y in the x-axis direction-causing machine system: y-axis component of the acceleration of the support member (first axis direction component) m _y: mass of the movable body that moves parallel to the y-axis direction together with the support member (Mass of the support member and the first movable body) _Ky : Elastic modulus in the y-axis direction of the machine tool system which causes the shape error ε _y v: The magnitude of the speed of the support member r: Radius of the processing circle

[0012]

１ ² = １ _x ² + ε _y ² (1)

[Number 2] _{F x = -m x a x =} K x ε x (x -axis direction inertia force) ... (2)

[Number 3] _{F y = -m y a y =} K y ε y (y -axis direction inertia force) ... (3)

[Number 4] _{ε x = -C x a x (} C x ≡m x / K x) ... (4)

[Number 5] _{ε y = -C y a y (} C y ≡m y / K y) ... (5)

A _x = a cos θ (6)

A _y = a sin θ (7)

Equation 8] ε (θ) = a {( C x cosθ) 2 + (C y sinθ) 2} 1/2 ... (8) where the angle theta of the epsilon (theta), last acceleration of the support member And the displacement (shape error ε)
Does not necessarily coincide with the direction.

The above C _x and C _y are the test circular machining or the test circular motion (idling) satisfying the following equation (9).
By performing the above, the values can be obtained as in equations (10) and (11).

A = v ² / r = (constant) (9)

C _x = ε (α) / a (α = 0, π) (10)

C _y = ε (β) / a (β = π / 2, 3π / 2) (11)

That is, if a circular processing with a radius r is performed and the shape error ε at that time is measured as a function ε (θ) of θ, m or m is calculated using a complicated or advanced analysis technique such as modeling or numerical calculation. _x, K _x, m _y, even when it is difficult to determine individually the values of _{K y, C x ≡m x /} K x, C y ≡m y /
The values of K _y (10), it becomes possible to obtain by (11).

Therefore, if the position command value is corrected using (4) and (5), a desired machining shape can be obtained even at the time of high-speed curve machining.

As can be seen from equations (2) and (3),
The present invention relates to a case where the mass of a movable body having a support member for supporting a supported object formed of a tool or a workpiece is large, or
Even in the case where the elastic modulus relating to the partial elastic deformation of the machine tool system is small, a large effect is exhibited in the same manner as described above.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on specific embodiments. 1 and 2 show a side view and a front view of a machine tool to which the present invention is applied. This machine tool is a linear motor drive type having three axes orthogonal to each other,
Its main components are a work table 11 arranged at the front of the base 10, a fixed frame 15 arranged at the rear of the base 10, and an x-axis guided by the base 10 and the fixed frame 15 at the front side of the fixed frame 15. 20 that horizontally moves in the direction, a saddle 50 that is guided by the gantry 20 and moves up and down in the y-axis direction, and a ram 60 that horizontally moves in the Z direction by the saddle 50 (a support member that supports a supported object made of a tool T). , The gantry 20, the saddle 50 constituting a part of the movable body, the electric linear motors 35, 37, 57, 67 for respectively moving the ram 60, the tool spindle 71 rotatably supported by the ram 60, and the like. .

The guide mechanism in each axial direction is such that the guide rails 29 and 32 and the bearing block 3
0, 31, 33, the y-axis direction is the guide rail 53,
The lower linear guide mechanism 61 and the upper linear guide mechanism 62 constitute the Z direction by the bearing 55 and the bearing blocks 54 and 56, respectively. The symbols T and W in FIG. 1 represent a tool and a workpiece, respectively.

FIG. 3 shows a physical conceptual diagram of a simplified model for explaining the operation of the present invention. Each numerical code is shown in FIG.
Alternatively, the same components as those in FIG. 2 are shown. 1 and 2
When a linear motor-driven machine tool is configured as shown in FIG. 1, since the tool or a support member supporting the tool is separated from each positioning point (the position indicated by a triangle in the figure), the machine tool A positioning error occurs due to the partial elastic deformation of.

Also, the moving mechanism in the y-axis direction is
A so-called container that is comprehensively integrated inside the moving mechanism
The x-axis of the workpiece shape error ε
Elastic deformation (shape error ε_xQuality of movable body that contributes to)
Quantity m_xAnd the amount of elastic deformation in the y-axis direction (shape error ε_yStop by
The mass m of the movable body to be given_y(M _x
> M_y> M; where m is the mass of the ram 60). I
However, in the present invention, each of the equations (4) and (5)
In order to correct the shape error for each axis,
Even if there is anisotropy in the shape amount, it is accurately compensated for each axis
Can be corrected.

FIG. 4 shows a hardware configuration diagram of the machine tool of the present embodiment. The numerical control device 100 includes a CPU 10
1, an interface unit (I / F) 103 for taking a physical interface with a memory 102 and a servo controller,
It has main components such as an input / output device 104. CPU1
In step 01, the x-, y-, and z-coordinate values (x, y, z) of the tool measured by the positioning device (linear scale) corresponding to each linear motor are input as needed via the I / F 103. In addition, the CPU 101 obtains, via the I / F 103, the respective values (dx, dy, dz) of the difference amounts that determine the position of the next interpolation point to be reached, obtained by the interpolation operation, via the x-axis servo controller 111, Output to the y-axis servo controller 112 and the z-axis servo controller 113 as needed.
The servo controllers 111 to 113 of the respective axes determine the difference amount (d
(x, dy, dz) to control the movement of the tool to the next interpolation point.

FIG. 5 shows a software configuration diagram of the numerical controller 100 of the present embodiment. NC program analysis unit 12
1 analyzes the given NC data,
2 performs an interpolation process based on the analyzed data. That is, the speed for each fixed interpolation cycle is obtained based on the commanded speed and a preset speed pattern, and the moving distance is obtained by the product of this speed and the interpolation cycle. Then, points (x, y, z) separated by the movement distance obtained on the machining curve given by the NC data are sequentially set as interpolation points. However, here, since this processing curve is simple, xy
It is assumed that it is on a coordinate plane (z = (constant value)).

The acceleration calculation unit 123 includes an interpolation calculation unit 122
The acceleration (ax _{, ay} ) at each interpolation point is calculated from the coordinates (x, y, z) of each interpolation point obtained in. Correction amount calculation unit 124 inputs the x-axis component a _x and y-axis components a _y of the acceleration of the tool at each interpolation point on the machining curve, equation (4), with (5), on the work curve Of each interpolation point (x,
y, x-axis direction of the shape error epsilon _x in z), and the y-axis direction the shape error epsilon _y determined.

The addition operation unit 125 calculates the coordinates (x, y, z) of each interpolation point on the machining curve input from the interpolation operation unit 122.
And the shape errors ε _x and y in the x-axis direction at the respective interpolation points (x, y, z) input from the correction amount calculation unit 124.
The position command value of each interpolation point is corrected to a coordinate value (x−ε _x , y−ε _y , z) based on the axial shape error ε _y . Then, the corrected position command value is output to each servo control device as needed. By performing the curve processing as described above, for example, when the above-described processing curve is a perfect circle, it is possible to realize the perfect circle processing with a desired accuracy.

The acceleration calculation in the acceleration calculation unit 123 may be performed by directly measuring the acceleration of the tool on a linear scale at the time of preliminary test machining without using the output of the interpolation calculation unit 122. That is, using the x-, y-, and z-coordinate values (x, y, z) of the tool input as needed via the I / F 103, the acceleration vector of the tool is directly tested in advance by a differential operation. It can be obtained by processing.

If the acceleration calculation in the acceleration calculation unit 123 is performed by trial processing using this method, the acceleration at each point on the processing curve can be easily obtained by a simple calculation even in the processing of a curve having a complicated shape. be able to. Therefore, the present invention, even when it is not easy to predict or schedule the acceleration at each point on the machining curve, by measuring the acceleration at each point at the time of preliminary trial machining, for any curve shape Even adaptation is easy.

In the above embodiment, for the sake of simplicity, concrete processing means for curve processing on the xy plane have been described. In this case also, the effect of the present invention can be obtained by the operation of the present invention.

In the above embodiment, for simplicity, the case where the x-axis and the y-axis are orthogonal to each other is shown. However, the independent relations as shown in the equations (4) and (5) are used. Is obtained, the means of the present invention can be applied.
Therefore, even in such a case, the effect of the present invention can be obtained by the operation of the present invention.

[Brief description of the drawings]

FIG. 1 is a side view showing a machine tool according to an embodiment of the present invention.

FIG. 2 is a front view showing the machine tool according to the embodiment of the present invention.

FIG. 3 is a physical conceptual diagram of a simplified model for explaining the operation of the present invention.

FIG. 4 is a hardware configuration diagram of the machine tool according to the embodiment of the present invention.

FIG. 5 is a software configuration diagram of the numerical control device according to the embodiment of the present invention.

[Explanation of symbols]

 100: Numerical control device 60: Ram T: Tool W: Workpiece

Continued on the front page F-term (reference) 3C001 KA01 KB04 KB09 TA02 TB02 TD01 5H269 AB01 BB03 CC02 EE01 EE05 EE13 GG08 QB17 RB11 RC04

Claims (5)

[Claims] 1. A numerical controller for moving a support member, which supports a supported object made of a tool or a workpiece, at high speed along a machining curve of the workpiece, wherein the workpiece is driven by acceleration of the support member or the like. The deviation of the path of the movement from the processing curve caused by the partial elastic deformation of the mechanical system is translated in the axial direction together with the predetermined acceleration of the support member and the support member for each axis component of the control axis. A position command value correction unit that corrects with a correction amount substantially proportional to a corresponding axis component of the acceleration based on a value related to the partial elastic deformation such as a mass and an elastic modulus of the movable body, or a deformation amount. A numerical controller characterized by the above-mentioned. 2. Supporting a supported object comprising a tool or a workpiece.
The second supporting member movably supports the supporting member to be moved in the first axial direction.
1 movable body, and the first movable body is perpendicular to a first axial direction.
A second movable support for movably supporting the second intersecting axial direction
And controlling the body so that the support member
Numerical control device for moving at high speed along
Of the first movable body due to the acceleration (a) of the supported object.
Machining the path of the movement caused by partial elastic deformation
Acceleration acting in the direction of the first axis to deviate from the curve
Degree (a_y) And the quality of the support member and the first movable body.
Quantity m_yAnd the elastic modulus of the first movable body (K_yRelated to the ratio
Related value (C_y), The first of the acceleration a
The axial component (a_y), The correction amount (ε_y)
And a partial elasticity of the second movable body due to the acceleration (a).
The path of the movement caused by the deformation from the machining curve
The displacement is determined by the acceleration (a) acting in the second axial direction._x)
And the support member, the first movable body, and the second
Mass of movable body (m_x) And the elastic modulus (K) of the second movable body.
_x) And the related value (C_x) Based on the
The second axial component of velocity (a_x) Is approximately proportional to
Positive quantity (ε _x) Is provided.
Numerical control device. 3. The numerical control device according to claim 2, wherein the related values (C _x, C _y ) are obtained experimentally in advance. 4. An acceleration (a _y ) acting in the first axis direction and an acceleration (a a) acting in the second axis direction.
4. The numerical controller according to claim 2, wherein _x ) is calculated from NC data for instructing the movement route. 5. The numerical control device according to claim 1, wherein at least one of the support member and each of the movable members is driven by a linear motor.