Shape measurement unit

Abstract

A shape measurement unit S100 comprises: a cylindrical housing 31 that has an opening 31a; an emission part 33 that is arranged within the housing 31 and that emits measurement light irradiated from the opening 31a toward a measurement object; a light-receiving part 35 that is arranged within the housing 31 and that receives reflected light obtained by the measurement light being reflected by the measurement object; and an optical element that is arranged within the housing 31 and that reflects or refracts the reflected light to the light-receiving part 35 side.

Description

Shape measurement unit

[0001] The present invention relates to a shape measurement unit.

[0002] Conventionally, measuring instruments that measure the shape of an object by triangulation using laser light have been known. For example, Patent Document 1 discloses a structure in which a measurement probe is attached to a tool holding portion of a machine tool.

[0003] Japanese Patent Application Laid-Open No. 2019-209466

[0004] However, the conventional technology has a problem in that the probe attached to the tool holding portion of the machine tool becomes large.

[0005] SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to reduce the size of a shape measuring unit that can be attached to a machine tool.

[0006] In one aspect of the present invention, a shape measurement unit is provided, comprising: a cylindrical housing having an opening; an emission section disposed within the housing that emits measurement light that is irradiated from the opening toward an object to be measured; a light receiving section disposed within the housing that receives reflected light of the measurement light reflected by the object to be measured; and an optical element disposed within the housing that reflects or refracts the reflected light toward the light receiving section, or reflects or refracts the measurement light from the emission section toward the object to be measured.

[0007] Fig. 6 is a diagram schematically showing a shape measuring unit and a machine tool according to a first embodiment; Fig. 7 is a block diagram showing the configuration of the machine tool and the shape measuring unit; Fig. 8 is a cross-sectional view showing the configuration of the shape measuring unit; Fig. 9 is a schematic diagram showing the configuration of the shape measuring unit; Fig. 10 is a diagram showing an example of a modified example of the present invention; Fig. 11 is a diagram showing a shape measuring unit according to a second embodiment; Fig. 12 is a diagram showing details of the structure of Fig. 6;

[0008] (First embodiment) Fig. 1 is a diagram schematically showing a shape measuring unit and a machine tool according to a first embodiment. Fig. 2 is a block diagram showing the configuration of the machine tool and the shape measuring unit. The up and down direction in Fig. 1 corresponds to the vertical direction (Z-axis direction).

[0009] The shape measuring unit S100 of this embodiment is a unit for measuring the shape of a workpiece W in a non-contact manner using triangulation. As shown in FIG. 1 , the shape measuring unit S100 is mounted on a machine tool 10. The specific structure of the shape measuring unit S100 will be described later. A key feature of the shape measuring unit S100 is that an emitting unit and a light receiving unit are provided in a housing that can be mounted on the machine tool 10, and a mirror that refracts light reflected from the workpiece W is also disposed within the housing. This type of configuration using a mirror allows for a smaller housing compared to a configuration in which the reflected light is directly received by the light receiving unit without using a mirror. The shape measuring unit S100 may be mounted in any direction and is not limited to the vertical direction.

[0010] 1, the machine tool 10 includes a stage 11, a moving mechanism 12, a tool holding unit 13, a tool driving mechanism 14, a control device 20, and a communication unit 25 (see FIG. 2). The machine tool 10 is, for example, a machining center.

[0011] The stage 11 has a mounting surface 11a on which a workpiece W, which is an object to be measured, is placed. The stage 11 is configured to be movable, for example, in directions along an X-axis and a Y-axis that are perpendicular to each other.

[0012] The moving mechanism 12 has a drive source (not shown) and moves the stage 11. The moving mechanism 12 moves the stage 11 to a predetermined position in accordance with a control signal from the control device 20.

[0013] The tool holder 13 is a component to which multiple types of tools are interchangeably attached. For example, the tool holder 13 is a shank that holds a columnar, cylindrical, or truncated conical member. Not only tools but also the shape measuring unit S100 can be attached to the tool holder 13.

[0014] The work of attaching the tool and the shape measuring unit S100 to the tool holding unit 13 may be performed by an operator or by an automatic tool changer. The automatic tool changer is a machine that automatically attaches any tool from among a plurality of tools held in a magazine to the tool holding unit 13. The automatic tool changer attaches the shape measuring unit S100 of this embodiment to the tool holding unit 13 in addition to the tool.

[0015] The tool driving mechanism 14 has a driving source (not shown), such as a motor. The tool driving mechanism 14 rotates the tool holding part 13 around a rotation axis in the Z-axis direction using power from the driving source. The operation of the tool driving mechanism 14 is controlled by the control device 20.

[0016] The control device 20 has a CPU (Central Processing Unit), RAM (Random Access Memory), and ROM (Read Only Memory). The control device 20 controls the operations of the moving mechanism 12 and the tool driving mechanism 14. The control device 20 is communicatively connected to the shape measuring unit S100 via a communication unit 25 (see FIG. 2).

[0017] The CPU reads various processing programs stored in the ROM and executes various processes. The RAM is used as a working area for the CPU and temporarily stores input data and processing results generated when the processing programs are executed. The ROM is a storage unit configured, for example, with a non-volatile semiconductor memory. The ROM stores various programs executable by the CPU, data used when the programs are executed, and data resulting from processing generated by the CPU's arithmetic operations.

[0018] (Regarding the Shape Measuring Unit S100) Fig. 3 is a cross-sectional view showing the configuration of the shape measuring unit. Fig. 4 is a schematic diagram showing the configuration of the shape measuring unit. As shown in Figs. 3 and 4, the shape measuring unit S100 has a housing 31, an emitting unit 33, a light receiving unit 35, and a mirror 36. As components not shown in Figs. 3 and 4, the shape measuring unit S100 has a communication module 55 and a control unit 50 as shown in Fig. 2.

[0019] The housing 31 is cylindrical and has an opening 31a at its bottom end, as shown in FIG. 3 . The housing 31 is, for example, a cylinder. A base end 31b on the outer periphery of the housing 31 can be attached to the tool holder 13 of the machine tool 10. In this example, the housing 31 is formed from a single member. The housing 31 is made of, for example, metal. The thickness of the peripheral wall of the housing 31 may be nonuniform in the circumferential direction, but is constant in this embodiment. Since the peripheral wall has a constant thickness, if the housing 31 deforms due to a temperature change, it is easy to calculate the dimensions of the deformed housing 31. This has the advantage of making it easy to correct detection results due to temperature changes. In this specification, the term "cylindrical" does not necessarily mean a shape in which the length of the cylinder is longer than the width of the cylinder.

[0020] The housing 31 may have a cylindrical or truncated conical portion (the entire shape does not have to be cylindrical), and the portion may be provided so as to be held by the tool holding portion 13. The wall thickness of the cylindrical or truncated conical body may be constant, for example.

[0021] The emission unit 33 is disposed within the housing 31. The emission unit 33 emits measurement light to be irradiated toward the workpiece W. As an example, the emission unit 33 emits laser light. In this example, the emission unit 33 is disposed near the opening 31a. Specifically, the emission unit 33 is disposed in an orientation such that the measurement light is parallel to the extension direction of the housing 31. The emission unit 33 may be fixed to the inner wall of the housing 31, or may be supported by a support member (not shown) fixed to the housing 31. In this example, the emission unit 33 is disposed so as not to protrude from the bottom end of the housing 31. The emission unit 33 may also be disposed so that a portion of it protrudes from the bottom end of the housing 31.

[0022] The light receiving unit 35 receives the measurement light reflected by the workpiece W. As shown in FIG. 3 , the light receiving unit 35 is disposed farther from the opening 31 a than the light emitting unit 33 and the mirror 36. The light receiving unit 35 has a light receiving lens 35 a and a light receiving element 35 b. The light receiving lens 35 a focuses light toward the light receiving element 35 b. The light receiving element 35 b is disposed so that its light receiving surface is inclined with respect to the optical axis of the light receiving lens 35 a. The light receiving unit 35 is disposed in a positional relationship such that the light receiving unit 35 and the light emitting unit 33 partially overlap when projected in the longitudinal direction of the housing 31. Similarly, the light receiving unit 35 is disposed in a positional relationship such that the light receiving unit 35 and the mirror 36 partially overlap when projected in the longitudinal direction of the housing 31. This arrangement prevents the housing 31 from becoming larger in diameter.

[0023] The mirror 36 is an optical element disposed within the housing 31. As shown in FIG. 3 , the mirror 36 is disposed closer to the opening 31 a than the light receiving unit 35. The mirror 36 reflects reflected light that enters the housing 31 through the opening 31 a toward the light receiving unit 35. Specifically, the mirror 36 reflects reflected light that is directed toward the radially outer side of the housing (the left side in FIG. 3 ) toward the radially inner side (the right side in FIG. 3 ). In this example, the mirror 36 is disposed so as not to protrude from the bottom end of the housing 31. The mirror 36 may also be disposed so that a portion of it protrudes from the bottom end of the housing 31.

[0024] The effect of providing the mirror 36 will be described with reference to Fig. 4. If the mirror 36 were not provided, the light receiving unit 35 would need to be provided at the position shown by the dashed line in Fig. 4 in order to properly receive the light reflected from the workpiece W. This would result in a larger size of the housing 31 (outer and inner diameters of the cylinder). On the other hand, with the configuration in which the mirror 36 reflects the reflected light toward the light receiving unit 35 as in this embodiment, the effect of being able to reduce the size of the housing 31 is achieved.

[0025] The communication module 55 (see FIG. 2) is a module for wirelessly communicating with an external device. The communication module 55 is disposed inside the housing 31, for example.

[0026] The control unit 50 (see FIG. 2) has a CPU (Central Processing Unit), RAM (Random Access Memory), and ROM (Read Only Memory). The basic functions of the CPU, RAM, and ROM are similar to those of the control device 20 described above, and therefore a description thereof will be omitted. The control unit 50 is disposed, for example, inside the housing 31.

[0027] The control unit 50 controls the operation of the emission unit 33. The control unit 50 also transmits the detection result of the light receiving unit 35 (i.e., the electrical signal output from the light receiving unit 35) to the outside via the communication module 55. The control unit 50 may transmit the detection result to a computer (not shown) that is a shape measuring machine, or may transmit it to the machine tool 10. The communication module 55 may be configured to transmit the detection result to the outside via a wired system. To achieve wireless transmission, the communication module 55 may be configured to include a wireless communication unit that transmits a signal of the detection result wirelessly.

[0028] Effect of First Embodiment As described above, in the shape measuring unit S100 of this embodiment, the emitter 33 and the light receiver 35 for performing shape measurement by triangulation are arranged inside the housing 31 that can be attached to the tool holding unit 13 of the machine tool 10. Furthermore, since the mirror 36 is configured to reflect reflected light toward the light receiver 35, the housing 31 can be made smaller than in a configuration in which the light receiver 35 directly receives the reflected light.

[0029] When the housing 31 is small like this, for example, an auto-tool changer can hold the housing 31, and just as the auto-tool changer can attach a desired tool to the machine tool 10, the auto-tool changer can attach the shape measurement unit S100 to the machine tool 10.

[0030] Furthermore, the configuration of this embodiment using the mirror 36 increases the degree of freedom in the placement of the light-receiving lens 35a and the light-receiving element 35b. Therefore, a long distance (back focus) between the light-receiving lens 35a and the light-receiving element 35b can be ensured, which in turn reduces image aberration and out-of-focus, and is expected to improve detection accuracy.

[0031] In this embodiment, the mirror 36 is disposed on the side closer to the opening 31 a in the longitudinal direction of the housing 31, and the light receiving unit 35 is disposed on the side farther from the opening 31 a. In this manner, the configuration in which the mirror 36 and the light receiving unit 35 are disposed at offset positions along the longitudinal direction of the housing 31 allows the housing 31 to be made thinner than a configuration in which the mirror 36 and the light receiving unit 35 are disposed at the same position in the longitudinal direction of the housing 31 (i.e., a configuration in which the mirror 36 and the light receiving unit 35 are disposed in the radial direction of the housing 31).

[0032] In this embodiment, the housing 31 is formed from a single member, and the thickness of the peripheral wall is constant. With this configuration, as described above, it is easy to calculate the dimensions of the housing 31 after deformation and to correct the detection results due to temperature changes.

[0033] (Modification) The present invention is not limited to the specific structure described above, and may be modified in various ways. Fig. 5 is a diagram showing an example of a modification of the present invention. The shape measurement unit S101 in Fig. 5 has a prism 37 instead of the mirror 36. The other components are the same as those of the shape measurement unit S100 described above, so a description thereof will be omitted.

[0034] The prism 37 is an optical element that refracts light reflected from the workpiece W toward the light receiving unit. Specifically, as an example, the prism 37 refracts the reflected light in a direction parallel to the longitudinal direction of the housing 31. As in the above embodiment, the prism 37 may refract reflected light directed radially outward from the housing 31 toward the radially inward direction. As an example, the prism 37 is disposed near the opening 31 a. The prism 37 may be fixed directly to the housing 31, but in this example, it is fixed to the housing 31 via a mounter (not shown).

[0035] As an example, the prism 37 is arranged such that the prism 37 and the light receiving unit 35 are positioned on a straight line L. The straight line L is a line that extends in a direction parallel to the longitudinal direction of the housing 31. In this example, the straight line L is a line that passes through the center of the light receiving lens of the light receiving unit 35.

[0036] With this configuration, the prism 37 and the light receiving unit 35 are arranged on the straight line L, which is the direction in which the housing 31 expands and contracts in response to temperature changes in the housing 31, making it easy to calculate the dimensions of the housing 31 after deformation and to correct the detection results due to temperature changes.

[0037] The optical element is not limited to one, and for example, a plurality of mirrors 36, a plurality of prisms 37, or a combination of mirrors 36 and prisms 37 may be provided within the housing 31.

[0038] Second Embodiment Fig. 6 is a diagram showing a shape measurement unit according to a second embodiment. The shape measurement unit S102 in Fig. 6 has a housing 31, an emitting unit 33, a light receiving unit 35, and a mirror 36. These components are the same as those in the first embodiment, but the positions of the emitting unit 33, the light receiving unit 35, and the mirror 36 are changed.

[0039] The emitting unit 33 is disposed on the side farther from the opening 31 a and oriented such that the measurement light is emitted radially outward from the housing 31 .

[0040] The light receiving unit 35 is disposed closer to the opening 31 a than the light emitting unit 33. The light receiving unit 35 receives reflected light that has entered the housing 31 through the opening 31 a. The light receiving unit 35 is disposed in a positional relationship such that the light receiving unit 35 and the light emitting unit 33 partially overlap when projected and viewed in the longitudinal direction of the housing 31.

[0041] The mirror 36 reflects the measurement light from the emission unit 33 toward the measurement target, that is, the workpiece W. The mirror 36 may be fixed to the inner surface of the housing 31, or may be fixed to the housing 31 via a support member (not shown).

[0042] The contour shape of the mirror 36 is arbitrary. In the present embodiment, the contour shape of the mirror 36 is, for example, circular. When the housing 31 is cylindrical and the inner surface is curved, the mirror 36 having a circular shape like this allows the mirror 36 to be disposed close to the inner surface of the housing 31. The mirror 36 may be at least partially formed in an arc shape or an elliptical arc shape.

[0043] The advantages of having the mirror 36 close to the inner surface of the housing 31 are as follows. For example, as shown by the dashed line in Figure 6, in a configuration in which the emission unit 33-1 is located near the opening 31a, the distance between the position of the measurement light emitted from the emission unit 33-1 and the light-receiving unit 35 is distance d2. On the other hand, when the mirror 36 is used, the distance between the position of the measurement light and the light-receiving unit 35 is distance d1, which is longer than distance d2. The reason for this is that the size of the housing that houses the light source in the emission unit 33-1 is larger than the mirror 36, so the emission position of the measurement light from the emission unit 33-1 is farther from the inner surface of the housing 31.

[0044] In the configuration of this embodiment, the distance d2 between the emission unit 33 and the light receiving unit 35 is relatively short. In triangulation, the longer the distance between the position where the measurement light is emitted and the light receiving unit, the larger the angle of incidence on the light receiving unit 35, thereby improving measurement accuracy. Therefore, the shape measuring unit S102 of this embodiment is advantageous not only in reducing the size of the housing 31 but also in improving measurement accuracy. Furthermore, in the shape measuring unit S102, the path of the measurement light from the emission unit 33 to the workpiece W is longer than in the first embodiment, so the beam diameter within the FOV (Field of View) can be made more uniform, resulting in more stable measurement.

[0045] The detailed structure of FIG. 6 will be further explained with reference to FIG. 7 . FIG. 7 is a diagram showing the details of the structure of FIG. 6 . The emission unit 33 has a housing 33a and an emission member 33b provided in a part of the housing 33a. Distance d3 is the distance from the emission member 33b to the side surface of the housing 33a. The mirror 36 is preferably provided at a position where the distance d4 between the measurement light reflected by the mirror 36 and passing through the opening 31a and the inner wall of the housing 31 is shorter than the distance d3 from the emission member 33b to the side surface of the housing 33a. With this configuration, compared to when the emission unit 33-1 is provided at the position indicated by the dashed line, the distance between the position where the measurement light is emitted and the light receiving unit is longer, thereby achieving the above-mentioned effect of improving measurement accuracy.

[0046] (Modifications) The shape measurement unit of the present invention is not limited to the specific structure described above. While the mirror 36 is circular in the above example, the mirror 36 may have an arc-shaped or elliptical arc-shaped portion adjacent to or in contact with the inner surface of the housing 31, and the contours of the remaining portions may be formed in any shape other than an arc-shaped or elliptical arc-shaped portion. A battery that supplies power to one or more of the light-emitting unit, the light-receiving unit, the control unit, and the communication module may be built into the housing 31. The mirror 36 may have any shape, such as a rectangle or a polygon.

[0047] The present invention has been described above using embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. For example, all or part of the device can be configured by functionally or physically distributing or integrating in any unit. Furthermore, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiments resulting from the combination also have the effects of the original embodiments.

[0048] This application discloses the following invention: (Supplementary Note 1) A shape measurement unit including: a cylindrical housing having an opening, an emission unit disposed within the housing and emitting measurement light to be irradiated from the opening toward a measurement object, a light receiving unit disposed within the housing and receiving light reflected from the measurement object, and an optical element disposed within the housing and reflecting or refracting the reflected light toward the light receiving unit, or reflecting or refracting the measurement light from the emission unit toward the measurement object.

[0049] (Appendix 2) A shape measurement unit as described in Appendix 1, wherein the optical element is arranged on the side closer to the opening in the longitudinal direction of the housing, and the light receiving unit is arranged on the side farther from the opening in the longitudinal direction.

[0050] (Appendix 3) A shape measuring unit according to appendix 1 or 2, wherein the housing has a cylindrical or truncated cone-shaped portion that can be attached to a tool holding portion of a machine tool.

[0051] (Appendix 4) A shape measurement unit as described in Appendix 3, wherein the optical element reflects or refracts the reflected light that enters the housing from the opening and travels radially outward from the housing toward the radially inward direction or a direction parallel to the longitudinal direction of the housing.

[0052] (Appendix 5) A shape measuring unit according to appendix 3, wherein the housing is formed from a single member and the thickness of the peripheral wall is constant in the circumferential direction.

[0053] (Appendix 6) A shape measurement unit as described in Appendix 3, wherein the optical element is a prism that refracts the reflected light toward the light receiving unit, and the prism and the light receiving unit are arranged on a straight line extending in a direction parallel to the longitudinal direction of the housing.

[0054] (Appendix 7) A shape measurement unit as described in Appendix 3, wherein the light receiving unit is arranged on the side closer to the opening in the longitudinal direction of the housing, the light emitting unit is arranged on the side farther from the opening in the longitudinal direction, and the optical element is a mirror that reflects the measurement light emitted from the light emitting unit radially outward from the housing toward the object to be measured.

[0055] (Appendix 8) A shape measurement unit as described in Appendix 3, wherein the optical element is a mirror having at least a portion of its outer periphery formed in an arc or elliptical arc shape, and the arc or elliptical arc portion is positioned so as to be close to or in contact with the inner surface of the cylindrical or truncated cone-shaped housing.

[0056] (Supplementary Note 9) The shape measurement unit according to Supplementary Note 3, wherein the optical element is a mirror formed in a rectangular or polygonal shape.

[0057] (Appendix 10) A shape measurement unit as described in Appendix 7, wherein the emission section has a housing and an emission member provided in a part of the housing, and the mirror is provided at a position where the distance between the measurement light reflected by the mirror and passing through the opening and the inner wall of the housing is shorter than the distance from the emission member to the side of the housing.

[0058] (Supplementary Note 11) The shape measurement unit according to Supplementary Note 1 or 2, further comprising a communication module arranged within the housing and transmitting the detection result of the light receiving unit to an external device.

[0059] (Supplementary Note 12) The shape measurement unit described in Supplementary Note 11, wherein the communication module includes a wireless communication unit that transmits a signal of the detection result wirelessly.

[0060] REFERENCE SIGNS LIST 10 Machine tool 11 Stage 11a Placement surface 12 Moving mechanism 13 Tool holding section 14 Tool driving mechanism 20 Control device 25 Communication section 31 Housing 31a Opening 31b Base end 33 Emission section 33a Housing 33b Emission member 33-1 Emission section 35 Light receiving section 35a Light receiving lens 35b Light receiving element 36 Mirror 37 Prism 50 Control section 55 Communication module d1 Distance d2 Distance L Straight line S100 Shape measuring unit S101 Shape measuring unit S102 Shape measuring unit W Workpiece

Claims

1. A shape measurement unit comprising: a cylindrical housing having an opening; an emission unit disposed within the housing for emitting measurement light that is irradiated from the opening toward an object to be measured; a light receiving unit disposed within the housing for receiving light that is reflected from the object to be measured; and an optical element disposed within the housing for reflecting or refracting the reflected light toward the light receiving unit, or for reflecting or refracting the measurement light from the emission unit toward the object to be measured.

2. A shape measuring unit as described in claim 1, wherein the optical element is arranged on a side closer to the opening in the longitudinal direction of the housing, and the light receiving unit is arranged on a side farther from the opening in the longitudinal direction.

3. A shape measuring unit according to claim 1 or 2, wherein the housing has a cylindrical or truncated conical portion that can be attached to a tool holding portion of a machine tool.

4. A shape measurement unit as described in claim 3, wherein the optical element reflects or refracts the reflected light that enters the housing from the opening and travels radially outward from the housing, toward the radially inward direction or in a direction parallel to the longitudinal direction of the housing.

5. The shape measuring unit according to claim 3, wherein the housing is formed from a single member, and the thickness of the peripheral wall is constant in the circumferential direction.

6. A shape measurement unit as described in claim 3, wherein the optical element is a prism that refracts the reflected light toward the light receiving unit, and the prism and the light receiving unit are arranged on a straight line extending in a direction parallel to the longitudinal direction of the housing.

7. A shape measurement unit as described in claim 3, wherein the light receiving unit is arranged on a side closer to the opening in the longitudinal direction of the housing, the light emitting unit is arranged on a side farther from the opening in the longitudinal direction, and the optical element is a mirror that reflects the measurement light emitted from the light emitting unit radially outward of the housing toward the object to be measured.

8. A shape measurement unit as described in claim 3, wherein the optical element is a mirror having at least a portion of its outer periphery formed in an arc or elliptical arc shape, and the arc or elliptical arc part is positioned so as to be close to or in contact with the inner surface of the cylindrical or truncated cone-shaped housing.

9. The shape measuring unit according to claim 3, wherein the optical element is a mirror formed in a rectangular or polygonal shape.

10. A shape measurement unit as described in claim 7, wherein the emission section has a housing and an emission member provided in a part of the housing, and the mirror is provided at a position where the distance between the measurement light reflected by the mirror and passing through the opening and the inner wall of the housing is shorter than the distance from the emission member to the side of the housing.

11. The shape measuring unit according to claim 1 or 2, further comprising a communication module disposed within the housing for transmitting the detection result of the light receiving unit to an external device.

12. The shape measuring unit according to claim 11, wherein the communication module includes a wireless communication unit that transmits the detection result signal wirelessly.

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