TWI496651B - Detection apparatus and detection method by using the same - Google Patents

Description

Detection device and detection method using same

The present invention relates to a detecting device and a detecting method, and more particularly to an error for detecting a multi-axis machine tool and a detecting method using the same.

As industrial technology continues to advance, products can be processed through machine tools to meet the needs of high-efficiency machining. For example, the machine tool can be made into a three-axis machine tool by means of a mechanism that is arranged to move on three linear axes. In addition, through the existing three linear axis mechanisms and two rotating shaft mechanisms, the machine tool can be used as a five-axis machine tool, which can cope with increasingly complex surface machining or more complex parts such as fan blades and engine cylinders. . Since the five-axis machine tool can have the characteristics of five axes, it can greatly shorten the processing time and increase the production efficiency. Therefore, the five-axis machine tool has gradually received attention and use in the industry.

In order to improve the technical grade and processing precision of the above multi-axis machine tool to meet the high quality requirements of the product, it can be improved in two aspects. One is to improve the structural accuracy of the overall machine tool, but this is more time-consuming and labor-intensive, and cannot quickly solve the urgent needs of the industry. The other is to detect the machine tool by using the detecting device. The error and the accuracy of the machine tool are also improved by the error compensation method. This method is not only fast and simple. Therefore, most of the industry currently refers to the error of the inspection machine tool to the technical level and processing density of the machine tool.

According to the above, in the conventional detection of the error of the five-axis machine tool, it can be achieved by means of a double ball bar (DBB), a laser interferometer, an electronic level device and the like. However, the detection information of these devices can only obtain single-axis errors, and it is not possible to obtain multi-axis errors at the same time. Therefore, the detection of multi-axis simultaneous motion of the five-axis machine tool has been improved.

The invention provides a detecting device having two beams with an acute angle, and two beams are respectively incident on two position sensors to simultaneously detect multi-axis errors of the multi-axis machine tool.

The present invention provides a detection method for simultaneously detecting a multi-axis error of a multi-axis machine tool by the above-described detecting device.

The detection device of the present invention is used to detect errors in a multi-axis machine tool. The multi-axis machine tool has a rotating shaft and a main shaft. The detecting device comprises a housing, a light source, an optical mirror, a first position sensor, a second position sensor and a ball lens. The housing is disposed on the main shaft. The light source is disposed within the housing and emits a light beam. The optical lens assembly is disposed in the housing. The first beam and the second beam are generated as the beam passes through the optics. The ball lens is disposed on the rotating shaft and has a reflective layer and has a sensing distance between the ball lens and the light source. The first position sensor and the second sensor are disposed on both sides of the light source. When the shaft rotates and When the main shaft cooperates with the rotating shaft, the first beam and the second beam are respectively incident on the ball lens and reflected by the reflecting layer, and the first beam and the second beam are at an acute angle. The first beam and the second beam are respectively incident on the first position sensor and the second position sensor, and the first position sensor and the second position sensor can detect whether the sensing distance is changed and respectively generate A detection result.

The detection method of the present invention is suitable for use in a detection device to detect errors in a multi-axis machine tool. The multi-axis machine tool has a rotating shaft and a main shaft. The detecting device comprises a housing, a light source, an optical mirror, a first position sensor, a second position sensor and a ball lens. The housing is disposed on the main shaft. The ball lens is disposed on the rotating shaft and has a reflective layer and has a distance between the ball lens and the light source. The light source and the optical mirror are disposed in the housing, and the first position sensor and the second position sensor are disposed on both sides of the light source. The detecting method comprises: generating a first beam and a second beam by passing the beam of the light source through the optical lens group, and moving by the rotating shaft and the spindle. The first light beam and the second light beam are incident on the ball lens and the reflective layer reflects the first light beam and the second light beam at an acute angle, the first light beam is incident on the first position sensor, and the second light beam is incident on the second position. Sensor. The first position sensor and the second position sensor detect whether the sensing distance is changed and respectively generate a detection result.

In an embodiment of the invention, the first position sensor has a first sensing surface and the second position sensor has a second sensing surface. When the rotating shaft rotates about the first rotating shaft of the multi-axis machine tool and the sensing distance is changed, the first sensing surface has a first offset and a second offset, and the second sensing surface has a third offset. The first offset, the second offset, and the third offset are respectively parallel to the first linear axis of the multi-axis machine tool, and the second Linear axis and third linear axis.

In an embodiment of the invention, the extending direction of the rotating shaft and the extending direction of the main shaft are perpendicular to each other, and the first rotating shaft is parallel to the third linear axis.

In an embodiment of the invention, the extending direction of the rotating shaft and the extending direction of the main shaft are parallel to each other, and the first rotating shaft is parallel to the third linear axis.

In an embodiment of the invention, the multi-axis machine tool has a working platform. The rotating shaft is disposed on the working platform, and the working platform is adapted to rotate about a second rotating shaft. The extending direction of the rotating shaft is perpendicular to the extending direction of the main shaft, and the first rotating shaft is parallel to the third linear axis when the working platform is not rotated, and the second rotating shaft is parallel to the second linear axis.

In an embodiment of the invention, the ball lens has a refractive index and the refractive index is 2. When the first beam and the second beam are respectively incident on the ball lens and focused on the center of the reflective layer, the first incident direction of the first beam is parallel to the first exit direction, and the second incident direction of the second beam is The two exit directions are parallel to each other.

In an embodiment of the invention, the optical lens group includes a first polarized beam splitter (PBS), a second polarized beam splitter, and a first quarter wave plate (Quarter Wave Plate, QWP). ) with a second quarter wave plate. The first polarizing beam splitter is disposed between the first quarter wave plate and the light source, and the first position sensor and the second polarizing beam splitter are disposed on two sides of the first polarizing beam splitter, and the second The polarizing beam splitter is disposed between the second quarter wave plate and the second position sensor.

In an embodiment of the invention, the housing includes an upper cover and a bottom plate. The light source, the optical lens group, the first position sensor and the second position sensor are mounted on the bottom plate on. The upper cover has a rod body. When the upper cover is assembled with the bottom plate, the rod body is coupled to the main shaft.

In an embodiment of the invention, the first position sensor is a four-quadrant photo position sensor (QPD), a charge coupled device sensor (CCD sensor) or a complementary type. The second position sensor is a one-dimensional position sensor, a two-dimensional position sensor or a four-quadrant position sensor.

In an embodiment of the invention, the light source is a laser diode or a neon laser.

Based on the above, the light beam of the light source of the present invention forms two beams with acute angles after being reflected by the optical mirror and reflected by the reflective layer, and the two beams are respectively incident into the two position sensors to make two position senses The detector detects whether the sensing distance between the ball lens and the light source is changed to generate a detection result, respectively. Thereby, the detecting device can simultaneously detect the multi-axis error of the multi-axis machine tool as information for compensating the multi-axis machine tool.

The above described features and advantages of the invention will be apparent from the following description.

1, 1a, 1b‧‧‧ multi-axis machine tool

10‧‧‧ shaft

20‧‧‧ Spindle

30‧‧‧Working platform

100‧‧‧Detection device

110‧‧‧shell

112‧‧‧上盖

112a‧‧‧ rod body

114‧‧‧floor

120‧‧‧Light source

122‧‧‧ Beam

122a‧‧‧First beam

122b‧‧‧second beam

130‧‧‧Optical mirror

132‧‧‧First polarized beam splitter

134‧‧‧Second polarized beam splitter

136‧‧‧first quarter wave plate

138‧‧‧Second quarter wave plate

140‧‧‧Ball lens

142‧‧‧reflective layer

150‧‧‧First position sensor

152‧‧‧First sensing surface

160‧‧‧Second position sensor

162‧‧‧Second sensing surface

A1‧‧‧first rotating shaft

A2‧‧‧second rotating shaft

D1‧‧‧Sense distance

D2‧‧‧ shaft extension direction

D3‧‧‧Spindle extension direction

D4‧‧‧Injection direction

D5‧‧‧ outgoing direction

O‧‧‧ origin

P‧‧‧ incident point

P1‧‧‧ first offset

P2‧‧‧second offset

P3‧‧‧ third offset

X‧‧‧first linear axis

Y‧‧‧Second linear axis

Z‧‧‧third linear axis

S110~S130‧‧‧Steps

Θ‧‧‧ acute angle

1 is a schematic view of a detecting device applied to a multi-axis machine tool according to an embodiment of the present invention.

Figure 2 is a partial enlarged view of the detecting device of Figure 1 in a portion A.

Figure 3 is a schematic illustration of the detection device of Figure 2.

4 is a flow chart of a detecting method for a detecting device according to an embodiment of the present invention.

FIG. 5 is a schematic flow chart of the detecting device of FIG. 2 for a multi-axis machine tool.

FIG. 6 is a schematic diagram of detection of whether the first position sensor and the second position sensor of FIG. 3 are changed according to the sensing distance.

7 is a flow chart showing another embodiment of the detecting device of FIG. 2 for a multi-axis machine tool.

FIG. 8 is a flow chart showing still another embodiment of the detecting device of FIG. 2 for a multi-axis machine tool.

9 is a schematic diagram of the ball lens of FIG. 3 reflecting a first beam and a second beam.

1 is a schematic view of a detecting device applied to a multi-axis machine tool according to an embodiment of the present invention. Figure 2 is a partial enlarged view of the detecting device of Figure 1 in a portion A. Referring to FIGS. 1 and 2 , in the present embodiment, the detecting device 100 is used to detect an error of the multi-axis machine tool 1 , and the multi-axis power tool 1 has a rotating shaft 10 and a spindle 20 . Furthermore, the multi-axis machine tool 1 is, for example, a five-axis tool grinding machine, the shaft 10 of which can be rotated about a first axis of rotation A1, and the spindle 20 can be along a first linear axis X, a second linear axis Y and a third linear axis, respectively. The axis Z moves, wherein the first linear axis X, the second linear axis Y and the third linear axis Z are perpendicular to each other.

Figure 3 is a schematic illustration of the detection device of Figure 2. Please refer to Figure 2 and Figure 3, It should be noted that in order to make the view clear, FIG. 3 omits part of the components of the detecting device 100. The detecting device 100 includes a housing 110, a light source 120, an optical mirror 130, a ball lens 140, a first position sensor 150, and a second position sensor 160. The housing 110 is disposed on the main shaft 20. The light source 120 is disposed in the housing 110 and is configured to emit a light beam 122, wherein the light source 120 is, for example, a laser diode or a neon laser, so that the light beam 122 can have high directivity and high homology after being emitted. The optical lens assembly 130 is disposed within the housing 110. When the light beam 122 passes through the optical lens set 130, the first light beam 122a and the second light beam 122b are generated, wherein the first light beam 122a is, for example, the forward light beam of FIG. 3, and the second light beam 122b is, for example, the oblique light beam of FIG. The ball lens 140 is disposed on the rotating shaft 10 and has a reflective layer 142. The reflective layer 142 is made of aluminum or copper, for example, and has a sensing distance D1 between the ball lens 140 and the light source 120. The first position sensor 150 and the second position sensor 160 are disposed on both sides of the light source 120.

In the above, when the rotating shaft 10 rotates about the first rotating axis A1 and the main shaft 20 moves along the first linear axis X and the second linear axis Y in cooperation with the rotating shaft 10, the first light beam 122a and the second light beam 122b are respectively incident on the ball. The lens 140 is reflected by the reflective layer 142, and the first beam 122a and the second beam 122b are separated by an acute angle θ. Then, the first beam 122a and the second beam 122b are respectively incident into the first position sensor 150 and the second position sensor 160, and the first position sensor 150 and the second position sensor 160 can detect Whether the sensing distance D1 is changed to generate a detection result, wherein the detection result generated by the first position sensor 150 and the second position sensor 160 is, for example, when the rotating shaft 10 rotates around the first rotating axis A1. An offset on the first linear axis X, the second linear axis Y, and the third linear axis Z. Thereby, through two reflected beams (ie The first beam 122a and the second beam 122b are respectively incident on the first position sensor 150 and the second position sensor 160 to simultaneously detect the offsets of the plurality of linear axes of the shaft 10. In addition, since the first light beam 122a and the second light beam 122b are respectively reflected to the first position sensor 150 and the second position sensor 160 through the reflective layer 142, and the acute angle θ is sandwiched, the interior of the housing 110 can be effectively reduced. Space requirements. With this configuration, the overall size of the housing 110 can be reduced, and the detecting device 100 can be driven to the miniaturized product to facilitate mounting to the multi-axis machine tool 1.

4 is a flow chart of a detecting method for a detecting device according to an embodiment of the present invention. FIG. 5 is a schematic flow chart of the detecting device of FIG. 2 for a multi-axis machine tool. Referring to FIG. 3, FIG. 4 and FIG. 5, in detail, the housing 110 is mounted to the main shaft 20 of the multi-axis machine tool 1 and the ball lens 140 is mounted to the rotating shaft 10 of the multi-axis machine tool 1, and is adjusted to the light source 120 and the ball lens. After the sensing distance D1 is maintained between 140, the detecting device 100 starts to detect. First, in step S110, when the light beam 122 of the light source 120 passes through the optical lens group 130, the first light beam 122a and the second light beam 122b are generated, and the rotating shaft 10 rotates about the first rotating axis A1 and the spindle 20 rotates according to the rotating shaft 10. The first linear axis X and the second linear axis Y are moved to cause the main shaft 20 to move in the same manner as the rotational path of the rotary shaft 10 and to continuously inject the first light beam 122a and the second light beam 122b into the ball lens 140.

Next, in step S120, after the first beam 122a and the second beam 122b are incident on the ball lens 140, the reflective layer 142 of the ball lens 140 reflects the first beam 122a and the second beam 122b and causes the two reflected beams to have an acute angle θ . When the first beam 122a and the second beam 122b pass through the optics 130 again, the first beam 122a is incident To the first position sensor 150, and the second light beam 122b is incident to the second position sensor 160.

Then, in step S130, the first position sensor 150 and the second position sensor 160 detect whether the sensing distance D1 is changed and generate a detection result. In this way, it is possible to detect whether or not the axis of rotation 10 is offset on each linear axis when rotating.

FIG. 6 is a schematic diagram of detection of whether the first position sensor and the second position sensor of FIG. 3 are changed according to the sensing distance. Please refer to FIG. 2, FIG. 3 and FIG. 6. Specifically, the first position sensor 150 is, for example, a four-quadrant light position sensor, and the second position sensor 160 is, for example, a one-dimensional position sensor. In addition, the first position sensor 150 has a first sensing surface 152 , and the second position sensor 160 has a second sensing surface 162 . When the rotating shaft 10 rotates around the first rotating axis A1, the first light beam 122a and the second light beam 122b are reflected by the reflective layer 142 of the ball lens 140 and are incident on the first sensing surface 152 and the second sensing surface 162, respectively.

If the sensing distance D1 between the light source 120 and the ball lens 140 is changed, after the first light beam 122a is incident on the first sensing surface 152, the incident point P of the first light beam 122a and the first sensing surface 152 The first offset P1 has a first offset P1 and a second offset P2. The first offset P1 is an error of the first linear axis X detected by the first position sensor 150 when the rotating shaft 10 rotates. The second offset P2 is an error of the second linear axis Y detected by the first position sensor 150 when the rotating shaft 10 rotates. Since the ball lens 140 moves in conjunction with the rotation of the rotating shaft 10, and the direction in which the first light beam 122a is reflected by the ball lens 140 is parallel to the third linear axis Z, the incident point P of the first light beam 122a and the first sensing surface 152 The origin O coincides. In addition, the second light beam 122b is incident on After the second sensing surface 162, the incident point P of the second light beam 122b and the origin O of the second sensing surface 162 have a third offset P3, wherein the third offset P3 is when the rotating shaft 10 is rotated. The error of the third linear axis Z is detected.

On the contrary, after the first light beam 122a and the second light beam 122b are respectively incident on the first sensing surface 152 of the first position sensor 150 and the second sensing surface 162 of the second position sensor 160, the first light beam 122a The incident point P coincides with the origin O of the first sensing surface 152, and the incident point P of the second beam 122b coincides with the origin O of the second sensing surface 162, and the light source 120 and the ball lens 140 are The sensing distance D1 has not been changed. In other words, the rotating shaft 10 has no offset on each linear axis when rotated.

Therefore, the first light beam 122a and the second light beam 122b are respectively incident on the first position sensor 150 and the second position sensor 160, and the offsets of the three linear axes can be simultaneously obtained, and the first offset P1 is compensated. After the second offset P2 and the third offset P3, the error of the multi-axis machine tool 1 can be corrected. Thereby, the machine precision of the multi-axis machine tool 1 can be maintained.

In addition, in another embodiment, the first position sensor 150 may be a charge coupled device sensor or a complementary MOS sensor, and the second position sensor 160 may be a two-dimensional position sensor. Or four-quadrant position sensor. Further, the rotation axis extending direction D2 of the rotating shaft 10 of the multi-axis power tool 1 of the present embodiment is perpendicular to the main shaft extending direction D3 of the main shaft 20, and the first rotating shaft A1 is parallel to the third linear axis Z.

7 is a flow chart showing another embodiment of the detecting device of FIG. 2 for a multi-axis machine tool. Referring to FIG. 2, FIG. 5 and FIG. 7, in the present embodiment, the multi-axis machine tool 1a is similar to the multi-axis machine tool 1 of FIG. 5, wherein the same or similar component numbers are substituted. The same or similar elements are not listed here. The rotation axis extending direction D2 of the rotating shaft 10 of the multi-axis power tool 1a of the present embodiment is parallel to the main shaft extending direction D3 of the main shaft 20, and the first rotating shaft A1 is parallel to the third linear axis Z. After passing through the detecting step of FIG. 4, the error of each linear axis of the rotating shaft 10 at the time of rotation can be obtained. Therefore, the multi-axis machine tool 1b of the present embodiment differs from the multi-axis machine tool 1 of FIG. 5 in that the main shaft 20 of the present embodiment faces the rotating shaft 10, and the main shaft 20 of FIG. 5 is located at the side of the rotating shaft 10. In addition, the detection flow of the embodiment is the same as the detection flow of FIG. 5, which is to detect the error of the rotating shaft 10 by moving two linear axes and one rotating axis.

Figure 8 is a flow diagram of another embodiment of the detection device of Figure 2 for a multi-axis machine tool. Referring to FIG. 2, FIG. 5 and FIG. 8, in the present embodiment, the multi-axis machine tool 1b is similar to the multi-axis machine tool 1 of FIG. 5, wherein the same or similar component numbers represent the same or similar components. Let me repeat. The multi-axis machine tool 1b of the present embodiment further has a work platform 30 that rotates about the second rotation axis A2, and the rotation shaft 10 is disposed on the work platform 30. The rotation axis extending direction D2 of the rotating shaft 10 is perpendicular to the main shaft extending direction D3 of the main shaft 20, and the first rotating shaft A1 is parallel to the third linear axis Z when the working platform 30 is not rotated, and the second rotating shaft A2 and the second linearity The axis Y is parallel. After passing through the detecting step of FIG. 4, the error of each linear axis of the rotating shaft 10 at the time of rotation can be obtained. Therefore, the multi-axis machine tool 1b of the present embodiment is different from the multi-axis machine tool 1 of FIG. 5 in that the working platform 30 of the multi-axis machine tool 1b of the present embodiment rotates about the second rotation axis A2 and the rotating shaft 10 rotates around the first The rotation axis A1 rotates, and the multi-axis machine tool 1 of FIG. 5 is rotated only by the rotation shaft 10 about the first rotation axis A1, and the detection flow of the present embodiment detects the error of the rotation shaft 10 by moving three linear axes and two rotation axes. .

Referring to FIG. 3, the optical lens assembly 130 of the present embodiment includes a first polarizing beam splitter 132, a second polarizing beam splitter 134, a first quarter wave plate 136 and a second quarter wave plate 138. . The first polarizing beam splitter 132 is disposed between the first quarter wave plate 136 and the light source 120 , and the first position sensor 150 and the second polarizing beam splitter 134 are disposed on the first polarizing beam splitter 132 . On both sides, the second polarizing beam splitter 134 is disposed between the second quarter wave plate 138 and the second position sensor 160.

In detail, when the light source 120 emits the light beam 122, the light beam 122 enters the first polarizing beam splitter 132 to generate the first light beam 122a and the second light beam 122b. When the first light beam 122a passes through the first quarter wave plate 136, the first light beam 122a is a P circularly polarized light and is incident on the ball lens 140. After the reflective layer 142 of the ball lens 140 reflects the first light beam 122a and passes through the first quarter wave plate 136 again, the first light beam 122a is an S linearly polarized light and is reflected to the first through the first polarizing beam splitter 132. Position sensor 150.

As described above, when the second light beam 122b passes through the second polarization beam splitter 134 and the second quarter wave plate 138, the second light beam 122b is an S circularly polarized light and is incident on the ball lens 140. After the reflective layer 142 of the ball lens 140 reflects the second light beam 122b and passes through the second quarter wave plate 138 again, the first light beam 122a is a P-line polarized light and is reflected by the second polarizing beam splitter 134 to the second. Position sensor 160. In this way, the first quarter wave plate 136 and the second quarter wave plate 138 are respectively disposed on the passing paths of the first light beam 122a and the second light beam 122b, and the properties of the light can be changed to avoid the first light beam. The 122a or second beam 122b is passed into the interior of the source 120 to interfere with the source 120. Therefore, the detection accuracy of the detecting device 100 can be ensured.

9 is a schematic diagram of optical paths of the first beam and the second beam of FIG. Referring to FIG. 3 and FIG. 9, it should be noted that the incident mode and the reflection mode of the first light beam 122a and the second light beam 122b are similar, so that the light paths of the two light beams incident on the ball lens 140 and reflected from the ball lens 140 are illustrated in FIG. . In the present embodiment, when the refractive index of the material of the ball lens 140 is 2, and the first beam 122a and the second beam 122b are respectively incident on the ball lens 140 and focused on the center of the reflective layer 142, the incident of the first beam 122a The direction D4 and the exit direction D5 are parallel to each other, and the incident direction D4 and the outgoing direction D5 of the second light beam 122b are parallel to each other. Thereby, the incident light and the reflected light of the first light beam 122a can be parallel to each other, and the incident light and the reflected light of the second light beam 122b are parallel to each other, and help to maintain the detection accuracy of the detecting device 100.

Referring to FIG. 2 and FIG. 3 , the housing 110 of the embodiment includes an upper cover 112 and a bottom plate 114 . The light source 120, the optical lens assembly 130, the first position sensor 150 and the second position sensor 160 are mounted on the bottom plate 114. The upper cover 112 has a rod body 112a. When the upper cover 112 is assembled with the bottom plate 114, the rod 112a is coupled to the main shaft 20. Therefore, after the upper cover 112 and the bottom plate 114 are assembled, the light source 120, the optical lens assembly 130, the first position sensor 150 and the second position sensor 160 can be configured as a modular member to increase assembly to the main shaft 20. Convenience.

In summary, the present invention is incident on the first position sensor and the second position sensor through the first beam and the second beam, respectively, and simultaneously detects whether the sensing distance between the light source and the ball lens is changed. The offset of the multiple linear axes of the spindle. Therefore, the error of the multi-axis machine tool can be corrected after correcting these offsets. In addition, since the first beam and the second beam are respectively reflected by the reflective layer and are acutely angled, Effectively reduce the internal space requirements of the housing. Thereby, the overall size of the housing can be reduced and the detection device can be driven to miniaturize the product. Furthermore, when the quarter wave plate is respectively disposed on the passing paths of the first light beam and the second light beam, the first light beam and the second light beam can be prevented from entering the light source, thereby improving the detection accuracy of the detecting device. . In addition, when the refractive index of the ball lens is 2, the incident light of the first beam is parallel to the reflected light, and the incident light of the second beam is parallel to the reflected light, which can also improve the detection accuracy of the detecting device.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and any one of ordinary skill in the art can make some changes and refinements without departing from the spirit and scope of the present invention. The scope of the invention is defined by the scope of the appended claims.

100‧‧‧Detection device

110‧‧‧shell

114‧‧‧floor

120‧‧‧Light source

122‧‧‧ Beam

122a‧‧‧First beam

122b‧‧‧second beam

130‧‧‧Optical mirror

132‧‧‧First polarized beam splitter

134‧‧‧Second polarized beam splitter

136‧‧‧first quarter wave plate

138‧‧‧Second quarter wave plate

140‧‧‧Ball lens

142‧‧‧reflective layer

150‧‧‧First position sensor

152‧‧‧First sensing surface

160‧‧‧Second position sensor

162‧‧‧Second sensing surface

D1‧‧‧Sense distance

Θ‧‧‧ acute angle

Claims (15)

A detecting device for detecting an error of a multi-axis machine tool, wherein the multi-axis machine tool has a rotating shaft and a main shaft, the detecting device comprises: a casing disposed on the main shaft; a light source disposed in the casing And emitting a light beam; an optical lens set is disposed in the housing, wherein the light beam passes through the optical lens group to generate a first light beam and a second light beam; a ball lens is disposed on the rotating shaft and has a reflective layer And the ball lens and the light source have a distance; a first position sensor; and a second position sensor, and the first position sensor are disposed on both sides of the light source, when the shaft When the rotating shaft moves with the rotating shaft, the first light beam and the second light beam are respectively incident on the ball lens and are reflected by the reflective layer and are separated by an acute angle, and the first light beam and the second light beam are respectively incident on the ball beam. The first position sensor and the second position sensor, and the first position sensor and the second position sensor can detect whether the distance is changed and respectively generate a detection result. The detecting device of claim 1, wherein the first position sensor has a first sensing surface, and the second position sensor has a second sensing surface, and the rotating shaft surrounds the multi-axis When the first rotating shaft of the machine tool rotates and the distance is changed, the first sensing mask has a first offset and a second offset, and the second sensing mask has a third offset. The first offset, the second offset, and the third offset are respectively parallel to a first linear axis, a second linear axis, and a third of the multi-axis machine tool Linear axis. The detecting device of claim 2, wherein an extending direction of the rotating shaft is perpendicular to an extending direction of the main shaft, and the first rotating shaft is parallel to the third linear axis. The detecting device of claim 2, wherein an extending direction of the rotating shaft is parallel to an extending direction of the main shaft, and the first rotating shaft is parallel to the third linear axis. The detecting device of claim 2, wherein the multi-axis machine tool further has a working platform, the rotating shaft is disposed on the working platform, and the working platform is adapted to rotate around a second rotating shaft, An extending direction of the rotating shaft is perpendicular to an extending direction of the main shaft, and the first rotating shaft is parallel to the third linear axis when the working platform is not rotated, and the second rotating shaft is parallel to the second linear axis . The detecting device of claim 1, wherein the ball lens has a refractive index and the refractive index is 2, when the first beam and the second beam are respectively incident on the ball lens and focused on the reflection In a central portion of the layer, a first incident direction of the first beam is parallel to a first exit direction, and a second incident direction of the second beam is parallel to a second exit direction. The detecting device of claim 6, wherein the optical lens group comprises a first polarizing beam splitter, a second polarizing beam splitter, a first quarter wave plate and a second quarter a wave plate, the first polarizing beam splitter is disposed between the first quarter wave plate and the light source, and the first position sensor and the second polarizing beam splitter are disposed at the first Two sides of the polarizing beam splitter, and the second polarizing beam splitter is disposed on The second quarter wave plate is between the second position sensor. The detecting device of claim 1, wherein the housing comprises an upper cover and a bottom plate, and the light source, the optical lens group, the first position sensor and the second position sensor are mounted on the housing On the bottom plate, the upper cover has a rod body, and after the upper cover is assembled with the bottom plate, the rod body is connected to the main shaft. The detecting device of claim 1, wherein the first position sensor is a four-quadrant light position sensor, a charge coupled device sensor or a complementary MOS sensor, and the second The position sensor is a one-dimensional position sensor, a two-dimensional position sensor or a four-quadrant position sensor. The detecting device of claim 1, wherein the light source is a laser diode or a neon laser. A detecting method is applicable to a detecting device for detecting an error of a multi-axis machine tool having a rotating shaft and a main shaft, the detecting device comprising a casing, a light source, an optical mirror, and a first a position sensor, a second position sensor and a ball lens, the housing is disposed on the main shaft, the ball lens is disposed on the rotating shaft, the ball lens has a reflective layer, and the ball lens and the light source There is a distance between the light source and the optical lens group disposed in the housing, and the first position sensor and the second position sensor are disposed on two sides of the light source, and the detecting method comprises: a light beam of the light source passes through the optical lens group to generate a first light beam and a second light beam, and is rotated by the rotating shaft by the rotating shaft; the first light beam and the second light beam are incident on the ball lens and reflected The layer reflects the first beam and the second beam and forms an acute angle, and the first beam is incident on the first Positioning the sensor, and the second light beam is incident on the second position sensor; and detecting whether the distance is changed by the first position sensor and the second position sensor and respectively generating a detection result. The detecting method of claim 11, wherein the first position sensor has a first sensing surface, and the second position sensor has a second sensing surface, when the rotating shaft surrounds the When the first rotating shaft of the shaft machine rotates and the distance is changed, the first sensing mask has a first offset and a second offset, and the second sensing mask has a first The third offset, wherein the first offset, the second offset, and the third offset are respectively parallel to a first linear axis, a second linear axis, and a third linear axis of the multi-axis machine tool. The detecting method of claim 12, wherein an extending direction of the rotating shaft is perpendicular to an extending direction of the main shaft, and the first rotating shaft is parallel to the third linear axis. The detecting method of claim 12, wherein an extending direction of the rotating shaft is parallel to an extending direction of the main shaft, and the first rotating shaft is parallel to the third linear axis. The detection method of claim 12, wherein the multi-axis machine tool further has a working platform, the rotating shaft is disposed on the working platform, and the working platform surrounds a second rotating shaft of the multi-axis machine tool After the rotation, an extending direction of the rotating shaft is perpendicular to an extending direction of the main shaft, and the first rotating shaft is parallel to the third linear axis when the working platform is not rotated, and the second rotating shaft and the first rotating shaft The two linear axes are parallel.