Shape measuring device

Abstract

To provide a shape measuring device that can automatically perform high-precision shape measurements on objects with complex shapes in a short amount of time. [Solution] A translational movement mechanism and a rotational drive mechanism move the probe and the workpiece relative to each other, and the probe tracks and measures the workpiece along a preset tracking path. At this time, the rotational drive mechanism is driven and controlled in synchronization with the relative movement of the probe and the workpiece by the translational movement mechanism so that the angle between the probe and the workpiece surface becomes a desired angle.

Description

[Technical Field]

[0001] This invention relates to a shape measuring device. [Background technology]

[0002] Shape measuring devices are known that measure the shape of an object by moving a measuring probe along the surface of the object to be measured (see, for example, Patent Documents 1, 2, 3, 4, and 5). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 5274782 [Patent Document 2] Patent No. 6030339 [Patent Document 3] Patent No. 6063161 [Patent Document 4] Patent No. 7402653 [Patent Document 5] Patent No. 7344626 [Overview of the initiative] [Problems that the invention aims to solve]

[0004] In recent years, the shapes of objects being measured have become considerably more complex. Furthermore, there is a growing demand to measure (inspect) areas that were not previously considered part of the measurement (inspection) process. Moreover, there is a growing need to apply high-speed and high-precision contour measurement to even complexly shaped workpieces. On top of that, due to labor shortages, it is not feasible to perform these complex and difficult measurements (inspections) slowly and carefully, one by one, while making fine adjustments manually. Therefore, there is a need to efficiently automate the measurement process.

[0005] For example, it has become necessary to accurately measure (inspect) the surface contour shape of a curved surface such as the tooth surface of a gear, and further, to accurately evaluate, for example, the surface roughness as a detailed surface property. However, in performing high-precision measurement of the surface contour shape and surface roughness measurement, it is essential to perform tracing measurement while maintaining a state where a stylus (probe) hits the work surface at a predetermined angle (specifically, the displacement direction of the stylus and the work surface are perpendicular). For this reason, conventionally, the roughness of such a curved surface has not been an evaluation target, or some of them have been extracted and sampled manually for measurement.

[0006] There is a need for a shape measurement device that can automatically perform high-precision shape measurement on a measurement object with a complex shape in a short time. An object of the present invention is to provide a shape measurement device that can automatically perform high-precision shape measurement on a measurement object with a complex shape in a short time.

Means for Solving the Problems

[0007] A shape measurement device according to an embodiment of the present invention is a shape measurement device that relatively moves a probe and a work by a translation mechanism and a rotation drive mechanism, and the probe traces and measures the work along a preset tracing path, wherein the rotation drive mechanism is driven and controlled so that the angle formed by the probe and the work surface becomes a desired angle in synchronization with the relative movement of the probe and the work by the translation mechanism. This is the gist.

Brief Description of the Drawings

[0008] [Figure 1] It is a diagram showing the overall configuration of a shape measurement system. [Figure 2] It is a side view of a surface roughness measurement unit. [Figure 3] It is a diagram for explaining the internal mechanism of a stylus unit. [Figure 4] It is a diagram illustrating a rotation drive mechanism. [Figure 5] This is a functional block diagram of the host computer and motion controller. [Figure 6] This diagram schematically illustrates the relationship between design data and PCC curves. [Figure 7] This is a diagram illustrating a PCC curve. [Figure 8] This is a functional block diagram of the motion controller. [Figure 9] This figure shows an example of PCC curve data, translational velocity pattern, and rotation command for a tracing path. [Figure 10] This diagram schematically illustrates how the tooth surface of a gear is measured. [Figure 11] This diagram schematically illustrates how the tooth surface of a gear is measured. [Figure 12] This figure shows the configuration of the motion controller in the second embodiment. [Figure 13] This diagram illustrates the change in the normal direction of the workpiece surface. [Figure 14] This is a diagram illustrating a probe. [Figure 15] This diagram illustrates how the blade is measured using a probe. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be illustrated and described with reference to the reference numerals assigned to each element in the figures. Furthermore, each embodiment may be implemented not only individually, but also in combination of two or more embodiments, and the examples of modifications supplemented in each embodiment can be applied to other embodiments as well.

[0010] (First Embodiment) Figure 1 shows the overall configuration of the shape measuring system (shape measuring device) 100. The structural hardware components of the shape measurement system 100 are basically known and will be briefly explained. The shape measurement system 100 comprises a three-dimensional measuring machine 200, a motion controller 300 that controls the drive of the three-dimensional measuring machine 200, and a host computer 500 that controls the motion controller 300 and performs necessary data processing.

[0011] In this specification, shape measurement is not limited to obtaining measured values ​​related to the shape itself, such as contours and dimensions, but also includes obtaining parameters that represent the properties (characteristics) of the shape, such as surface texture (roughness and waviness), and broadly includes obtaining measured values ​​obtained by detecting the surface of a workpiece.

[0012] The three-dimensional measuring machine 200 comprises a surface plate 210, a translational movement mechanism 220, a probe 400, and a rotational drive mechanism 230.

[0013] The movement mechanism is composed of a translational movement mechanism 220 and a rotational drive mechanism 230.

[0014] The translational movement mechanism 220 includes a gate-shaped Y-slider 221 that is slidable in the Y direction on the surface plate 210, an X-slider 222 that slides along the X-direction beam of the Y-slider 221, a Z-axis column 223 fixed to the X-slider 222, and a Z-spindle 224 that moves up and down in the Z direction within the Z-axis column 223. In other words, in this embodiment, the translational movement mechanism 220 has three translational drive axes (X-direction translational drive axis, Y-direction translational drive axis, and Z-direction translational drive axis).

[0015] The Y slider 221, X slider 222, and Z spindle 224 are each equipped with a drive motor (not shown) and an encoder (not shown). Each drive motor is controlled by a drive control signal from the motion controller 300. The encoder detects the amount of movement of the Y slider 221, X slider 222, and Z spindle 224, and outputs the detected value to the motion controller 300. A probe 400 is attached to the lower end of the Z spindle 224.

[0016] In this embodiment, an example in which a surface roughness measuring unit 400 is used as the probe 400 will be described. Figure 2 is a side view of the surface roughness measurement unit 400.

[0017] The surface roughness measuring unit 400 comprises a stylus unit 410, an outer housing 450, and a joint 460.

[0018] The surface roughness measuring unit 400 is connected to the moving mechanism (specifically, the lower end of the Z spindle 224) by a joint 460.

[0019] Figure 3 is a diagram illustrating the internal mechanism of the stylus unit 410. The stylus unit 410 includes a case body 420 having an internal space, a stylus lever 430 that is pivotably mounted within the case body 420, and a displacement detection unit 440.

[0020] The case body 420 has a roughly rectangular body 421 and a nose portion 422 protruding from the tip of the body 421. A skid 423 is provided at the tip of the nose portion 422.

[0021] The skid 423 has an L-shaped through-hole 424 inside, which is continuous with the cavity in the nose section 422.

[0022] The stylus lever 430 is an L-shaped stylus overall. The stylus lever 430 includes a straight rod-shaped oscillating lever 431 and a stylus 433 provided at the tip of the oscillating lever 431 in a direction perpendicular to the oscillating lever 431. (In Figures 2 and 3, the stylus 433 is positioned facing downwards.) (For the sake of explanation, the vertical direction of the surface roughness measuring unit 400 will be defined and represented as shown on the paper in Figures 2 and 3. Furthermore, the left side of the paper will be represented as the front of the surface roughness measuring unit 400, and the right side of the paper will be represented as the rear of the surface roughness measuring unit 400.)

[0023] Here, the direction of the stylus 433, or the direction of the vertical displacement of the stylus 433, can be said to be the direction of the measurement axis of the probe, which is the surface roughness measurement unit 400.

[0024] The stylus lever 430 is inserted from the body 421 to the nose 422, and its tip, the stylus 433, is positioned to face outward from the lower end opening of the skid 423. The stylus lever 430 is attached to the internal space of the body 421 by a leaf spring 432 in its middle section. The leaf spring 432 serves as the pivot point for the stylus lever 430 and elastically supports the stylus lever 430 so that it is balanced with the stylus 433 slightly protruding from the lower surface of the skid 423.

[0025] The displacement detection unit 440 is located inside the body portion 421. The displacement detection unit 440 includes a ferrite plate 441 and an inductance detector 442.

[0026] The ferrite plate 441 is attached to the upper rear end surface of the stylus lever 430. An inductance detector 442 is mounted in the internal space of the body 421 at a position opposite the ferrite plate 441.

[0027] The lower surface of the skid 423 is the workpiece contact surface that contacts the workpiece W during measurement. As the lower surface of the skid 423 moves along the measurement surface of the workpiece W, the stylus 433 moves up and down according to the surface roughness of the measurement surface. When the stylus 433 moves up and down, this movement is detected by the inductance detector 442. The surface roughness (surface irregularities) of the workpiece W measurement surface is measured by the detection signal output from the inductance detector 442. The stylus unit 410 outputs the measurement result of the surface roughness of the workpiece W measurement surface to an external source. (It may be output to the motion controller 300 or directly to the host computer 500.)

[0028] The outer casing 450 houses the stylus unit 410 and has a joint 460 at its rear end. The outer casing 450 houses the stylus unit 410 such that its front end is exposed from the front end of the outer casing 450.

[0029] Generally, in the case of a surface roughness measuring unit 400 used independently, the outer housing 450 is provided with a power mechanism for sliding the stylus unit 410 in the front-rear direction and an encoder for detecting its displacement. The surface roughness measuring unit 400 used in this embodiment may also have such a power mechanism and encoder. In this case, the power mechanism for sliding the stylus unit 410 in the front-rear direction can be interpreted as the "movement mechanism (translational movement mechanism 220)". However, in this embodiment, the stylus unit 410 is assumed to be moved mainly by the translational movement mechanism 220, and therefore, the relative movement between the stylus unit 410 and the workpiece is assumed to be performed by the movement mechanism (translational movement mechanism 220 and rotational drive mechanism 230). The explanation of the power mechanism and encoder inside the outer housing 450 of the surface roughness measuring unit 400 is omitted.

[0030] Here, a surface roughness measuring instrument with skids is used as an example, but a skidless surface roughness measuring instrument without skids is also acceptable. The name is not important; it can be called a probe, following the convention of surface roughness measuring units, or a contour measuring instrument.

[0031] Figure 4 is an example of the rotary drive mechanism 230. The rotary drive mechanism 230 is a rotary table mechanism installed on the surface plate 210. The rotary drive mechanism 230 rotates the rotary table using a built-in motor (not shown). The rotary drive mechanism 230 has two rotation shafts (rotary drive shafts) and is a tilting rotary table mechanism that can further tilt the rotary table.

[0032] To accommodate workpieces with complex shapes, it is desirable to have a multi-axis (two axes in this case) rotary drive mechanism 230, but of course, a single rotation axis is also acceptable. (For example, if the curved surface being measured is parallel to a specific axis, then only one axis of rotation may be necessary.) In this embodiment, when measuring the tooth surface of a gear, it is sufficient to be able to rotate the gear around a single axis (e.g., the Y-axis), so a single-axis rotation drive mechanism 230 having a rotation axis parallel to the Y-axis is sufficient. The rotation drive mechanism 230 does not have to be a rotary table; it may be a mechanism that chucks the axis of the workpiece (the axis or shaft hole of the gear) and allows the workpiece (gear) to rotate.

[0033] (Host computer 500 configuration) Next, the host computer 500 will be described. Figure 5 is a functional block diagram of the host computer 500 and the motion controller 300. The host computer 500 is configured with a CPU 511 (Central Processing Unit), memory, etc., and controls the three-dimensional measuring machine 200 via the motion controller 300. The measurement operation of this embodiment is realized by executing a measurement control program on the CPU 511 (Central Processing Unit). In other words, the execution of the measurement control program may realize each functional part of the host computer 500 and the motion controller 300. The measurement control program may be recorded on a non-volatile recording medium (CD-ROM, memory card, etc.) and distributed, or it may be made available for download via the Internet connection, etc. Output devices (displays and printers) and input devices (keyboards and mice) are connected to the host computer 500 as needed.

[0034] The host computer 500 includes a storage unit 520 and a shape analysis unit 530. The memory unit 520 stores design data (CAD data, NURBS data, etc.) related to the shape of the object to be measured (workpiece) W, measurement data obtained from the measurement, and a measurement control program that controls the entire measurement operation.

[0035] The shape analysis unit 530 calculates surface shape data of the object to be measured based on the measurement data output from the motion controller 300, and performs shape analysis to determine the error, distortion, roughness (surface properties), etc. of the calculated surface shape data of the object to be measured.

[0036] Furthermore, the shape analysis unit 530 generates measurement command data by converting design data (CAD data, NURBS data, etc.) that includes tracing path information into PCC curves. Here, we will explain how to generate measurement command data. In this embodiment, the three-dimensional measuring machine 200 rotates the rotation drive mechanism 230 according to the shape of the workpiece, but instead of the operator setting the rotation command, it is assumed that the motion controller 300 (or host computer 500) automatically generates the rotation command from the PCC curve of the tracing path. Therefore, in this embodiment, the operator sets the tracing path as in the conventional way, and the shape analysis unit 530 of the host computer 500 converts the tracing path into a PCC curve, uses it as measurement command data, and provides it to the motion controller 300.

[0037] A brief explanation of an example procedure for converting design values ​​for a tracing path based on CAD data (for example, NURBS (Non-Uniform Rational B-Spline) data) into a group of polynomial curves of a predetermined order to obtain measurement command data is provided below. Figure 6 schematically shows the relationship between design data and the PCC curve. Figure 7 is an example of a PCC curve.

[0038] When the host computer 500 receives CAD data (e.g., NURBS data) containing path information from an external CAD system, it converts this CAD data into point cloud data. The data for each point is a combination of coordinate values ​​(x, y, z) and normal directions (P, Q, R) (i.e., (x, y, z, P, Q, R)). In this specification, point cloud data containing (x, y, z, P, Q, R) information will be referred to as contour point data.

[0039] Next, if necessary, the coordinate values of each point are offset by a predetermined amount in the normal direction. The predetermined offset amount is set in consideration of, for example, the reference point of the position (coordinates) of the probe 400 (the stylus lever 430), the distance from the reference point to the tip of the probe 400 (the stylus 433), and the assumed penetration amount from a predetermined measurement pressure. The point group data obtained in this way will be referred to as offset contour point data.

[0040] The offset contour point data is converted into a polynomial curve group of a predetermined degree. Here, a cubic function is used as the polynomial, and a PCC curve group (Parametric Cubic Curves) is used. Based on this PCC curve, a path for measuring the workpiece is generated. Further, the PCC curve is divided to form a divided PCC curve group.

[0041] The PCC curve is illustrated in FIG. 7. There is a continuous PCC curve L_PCC from point P1 to point P7, and the PCC curve L_PCC is divided into a plurality of segments by points P. (Each segment is also a PCC curve.) The end point of each segment is the start point of the next segment (PCC curve). The coordinates of the start point of the segment are represented as (K X0 , K Y0 , K Z0 ), and the length of the straight line between the start point and the end point of the PCC curve is represented as D. With this definition, the coordinates {X(S), Y(S), Z(S)} at an arbitrary position on the PCC curve are represented by the following equations using the coefficients (K X3 , K X2 ···· K Z1 , K Z0 ) for representing the cubic curve.

[0042] X(S)=K X3 S 3 +K X2 S 2 +K X1 S+K X0 Y(S)=K Y3 S 3 +K Y2S 2 +K Y1 S+K Y0 Z(S) = K Z3 S 3 +K Z2 S 2 +K Z1 S+K Z0

[0043] (Configuration of Motion Controller 300) Figure 8 is a functional block diagram of the motion controller 300. Let me explain the motion controller 300. The motion controller 300 includes a measurement command acquisition unit 310, a counter unit 330, a drive command generation unit 340, and a drive control unit 350.

[0044] The measurement command acquisition unit 310 acquires measurement command data from the host computer 500. In this case, the measurement command data is the PCC curve of the traced path described earlier.

[0045] Now, let's assume that the measurement command data is provided as PCC curve data for a traced path, as shown in the upper part of Figure 9. In the upper part of Figure 9, let's assume that the PCC curve is divided based on the change in curvature, that is, the PCC curve is divided into segments (Seg). In the upper part of Figure 9, for explanatory purposes, the normal direction of the work surface at the start and end points of each segment is shown.

[0046] The counter unit 330 measures the displacement of each slider by counting the detection signals output from the encoder of the translational movement mechanism 220. Similarly, the counter unit 330 obtains the rotation angle of the rotational drive mechanism 230 by counting the detection signals detected from the rotary encoder of the rotational drive mechanism 230. This allows the coordinate values ​​of the workpiece surface currently being measured by the stylus 433 of the probe 400 (surface roughness measuring unit 400) to be obtained.

[0047] The drive command generation unit 340 includes a speed pattern planning unit 341, a translation vector command generation unit 342, a rotation command generation unit 344, and a translation vector command correction unit 343.

[0048] The velocity pattern planning unit 341 divides the PCC curve into a group of divided PCC curves and then calculates a velocity curve from the group of divided PCC curves. That is, it calculates the movement speed (movement vector) of the probe 400 (surface roughness measuring unit 400) by the translational movement mechanism 220. Based on the curvature of each segment of the group of divided PCC curves, the movement speed (movement vector) of the probe 400 (surface roughness measuring unit 400) by the translational movement mechanism 220 is set, thereby generating the velocity pattern plan exemplified in the middle section of Figure 9. The applicant has disclosed in detail, for example, in Patent 6063161, how the velocity pattern is applied to each segment of the group of divided PCC curves to generate a series of velocity pattern plans like the one in the middle section of Figure 9.

[0049] The translation vector command generation unit 342 generates a translation vector command Vf as a drive command for the translational movement mechanism 220 according to the velocity pattern plan. In this embodiment, however, as will be described later, the translation vector command Vf does not directly become a command to drive the translational movement mechanism 220, but rather a corrected translation vector command Vf is generated after correction by the translation vector command correction unit 343. AMD This becomes the command to drive the translational movement mechanism 220. This point will be explained later.

[0050] The rotation command generation unit 344 generates a rotation command as a drive command for the rotation drive mechanism 230. In this embodiment, instead of the operator setting the rotation command, the rotation command generation unit 344 automatically generates the rotation command. Here, the rotation command for the rotation drive mechanism 230 is given not by coordinate values ​​(angle values), but by the moment-by-moment "angular velocity".

[0051] Looking at the upper and middle diagrams in Figure 9, for example, when performing a trace measurement (surface roughness measurement) on the k-th segment, the rotation command (angular velocity command) required is generated based on the difference in the workpiece normal direction between the start and end points of this k-th segment. Now, let the normal vector Nks be the direction of the normal vector at the starting point of the k-th segment. Let Nke be the normal vector, which is the direction of the normal at the endpoint of the k-th segment. Then, while the k-th segment is traced and measured by the probe 400 (surface roughness measuring unit 400), the change in the normal direction of the workpiece is given by the angle between the normal vector Nks and the normal vector Nke. We will represent the change in the normal direction of the workpiece during the tracing measurement of the K-th segment as Δθk(Nke;Nks).

[0052] Now, the time tk required to measure the k-th segment can be determined from the translational speed Vfk set by the speed pattern planning unit 341, and the length (distance) of the k-th segment. The rotational drive mechanism 230 is rotated to cancel out (cancel out) the change in the normal direction of the workpiece while the k-th segment is being measured. At this time, the rotation command (angular velocity command) ωk is set as follows.

[0053] ωk = Δθk(Nke;Nks) / tk

[0054] The translation vector command correction unit 343 corrects the translation vector command Vf generated by the translation vector command generation unit 342 to compensate for the rotation of the rotation drive mechanism 230, and then corrects the translation vector command Vf AMD Generates. Now, let's consider the case where, instead of the probe 400 (surface roughness measuring unit 400) moving diagonally downward to the right in Figure 10 (arrow A in Figure 10) along the tooth surface of the gear by the translational movement mechanism 220, the rotary table 251 rotates to the right (arrow B in Figure 11). In this case, the translation vector command Vf should be corrected to compensate for the rotation of the rotary drive mechanism 230.

[0055] Let the radius vector Ri be the vector pointing from the rotation axis of the rotary drive mechanism 230 to the probe 400 (surface roughness measuring unit 400; specifically, the point of contact between the tip of the stylus 433 and the workpiece surface). Furthermore, let ωk be the angular velocity vector of the rotational drive mechanism 230. The velocity (vector) of the rotational drive mechanism 230 at the position of the probe 400 (surface roughness measuring unit 400) (specifically, the contact point between the tip of the stylus 433 and the workpiece surface) is expressed as Vθk = ωk × Ri. The corrected translation vector command Vfk is obtained by adding this Vθk component to the translation vector command Vfk. AMD This can be calculated. (Gf and Gθ are appropriate gains.)

[0056] Corrected translation vector command Vfk AMD =Gf×Vfk+Gθ×Vθk

[0057] The drive control unit 350 includes a translational movement mechanism control unit 351 that drives and controls the translational movement mechanism 220, and a rotational drive mechanism control unit 352 that drives and controls the rotational drive mechanism 230. The translational movement mechanism control unit 351 receives the corrected translational vector command Vf from the translational vector command correction unit 343. AMD It is given. The rotation drive mechanism control unit 352 receives a rotation command ωk as a rotation drive command from the rotation command generation unit 344. Corrected translation vector command Vfk AMD The rotation command ωk is provided to the translational movement mechanism control unit 351 and the rotational drive mechanism control unit 352, respectively, while maintaining a synchronized state. The translational movement mechanism control unit 351 issues a corrected translational vector command Vfk to the translational movement mechanism 220. AMD A translational drive signal is provided based on the following. The rotary drive mechanism control unit 352 provides the rotary drive mechanism 230 with a rotation drive signal based on the rotation command ωk. At this time, the translational movement mechanism 220 and the rotational drive mechanism 230 are driven and controlled in a synchronous manner.

[0058] As a result of the synchronous drive of the translational movement mechanism 220 and the rotational drive mechanism 230, a tracing measurement operation like that shown in Figure 11 can be obtained. That is, for example, the movement of the probe 400 (surface roughness measuring unit 400) by the translational movement mechanism 220 is almost entirely in a straight line along the Y-axis. In conjunction with this, the rotary drive mechanism 230 rotates from side to side.

[0059] At this point, focusing on the normal direction of the workpiece, the normal direction of the workpiece surface at the point of contact between the tip of the stylus 433 and the workpiece surface (i.e., the measurement point) should not change while the probe 400 (surface roughness measuring unit 400) traces and measures the workpiece surface. Therefore, if the stylus 433 is approached perpendicularly to the workpiece surface at the initial starting point, the stylus 433 will always be perpendicular to the workpiece surface during subsequent tracing measurements. In other words, the surface roughness measuring unit 400 can correctly measure the surface roughness of curved surfaces such as the tooth surfaces of gears.

[0060] The measurement data includes the acquisition of the three-dimensional coordinates of the probe 400 (surface roughness measurement unit 400) by the encoder of the translational movement mechanism 220, and the amount of rotation of the rotational drive mechanism 230 acquired by the rotary encoder. (If the probe 400 (surface roughness measurement unit 400) itself has a built-in power mechanism and encoder, the displacement of the probe 400 itself can also be obtained.) For shape analysis of the workpiece (object to be measured), the displacement and rotation amounts from these drive mechanisms are taken into account and converted into coordinate values ​​of the measurement points.

[0061] With this configuration, this embodiment allows for tracing measurements while also utilizing the rotation of the rotary drive mechanism 230. Furthermore, while the probe 400 (surface roughness measuring unit 400) traces the workpiece surface, the relative orientation between the probe measurement axis and the workpiece at the point of contact (i.e., the measurement point) between the probe 400 and the workpiece surface can be kept constant or controlled (adjusted) to a desired value. Utilizing the rotation of the rotary drive mechanism 230 reduces the amount of drive required for the translational movement mechanism 220, leading to an improvement in measurement speed (measurement efficiency).

[0062] In this embodiment, the position of the probe 400 (surface roughness measuring unit 400) remains unchanged, and the probe 400 (surface roughness measuring unit 400) is only moved (translated) by the translational movement mechanism 220. In surface roughness measurement, the angle between the stylus 433 and the workpiece surface is important, and this is achieved by rotating the workpiece with the rotational drive mechanism 230 to adjust the workpiece's position. Thus, the fact that the position of the probe 400 (surface roughness measuring unit 400) does not change (in other words, the probe does not rotate) during workpiece tracing measurement is a significant advantage, for example, when using a probe where changes in position can easily lead to fluctuations in measurement conditions such as measurement pressure.

[0063] In this embodiment, only one translational axis and one rotational axis are driven during the measurement operation. By simplifying the movement during the measurement operation as much as possible, measurement error factors such as drive errors (trajectory errors) and speed fluctuations of the moving mechanism (translational movement mechanism 220, rotational drive mechanism 230) can be eliminated as much as possible. This leads to the achievement of groundbreakingly high measurement accuracy for workpieces with complex shapes that were previously difficult to measure.

[0064] In this embodiment, when measuring the surface roughness of one tooth surface of a gear, the tooth surface was measured using synchronous control combining one translational drive shaft (Y-direction translational drive shaft) and one rotational drive shaft. However, when measuring another tooth surface, another surface, or an end face, the surface to be measured may be measured using synchronous control combining another translational drive shaft (for example, an X-direction translational drive shaft) and another rotational drive shaft. Only one translational drive shaft of the translational movement mechanism 220 and one rotational drive shaft of the rotational drive mechanism 230 are driven simultaneously. Reducing the number of drive shafts moving simultaneously in this way leads to improvements in measurement accuracy and measurement efficiency.

[0065] (Second embodiment) Next, a second embodiment of the present invention will be described. The distinguishing feature of the second embodiment is that it obtains information about the normal of the workpiece surface at the current measurement point from the coordinate values ​​of the current measurement point, and generates a rotation command in real time so as not to change the normal direction of the workpiece surface. Figure 12 shows the configuration of the motion controller 300 according to the second embodiment. Compared to the first embodiment (Figure 8), the rotation command generation unit 344 receives position information from the counter unit 330 in real time. As a result, the rotation command generation unit 344 constantly obtains information on the coordinate values ​​(current measurement point) of the workpiece surface that the probe 400 (surface roughness measurement unit 400) stylus 433 is currently measuring.

[0066] Furthermore, the rotation command generation unit 344 is equipped with a reference vector setting unit (reference direction setting unit) 345. This reference vector setting unit 345 sets a reference direction (reference vector) and stores it. For example, the reference vector is the normal direction (normal vector) of the workpiece surface at the initial starting point. The normal direction (normal vector) of the workpiece surface at the initial starting point is included in the measurement command data. The reference vector setting unit 345 sets the normal direction (normal vector) of the workpiece surface at the initial starting point as the reference vector N b It will be saved as a setting.

[0067] In the first embodiment, the rotation command generation unit 344 determines the change in the normal direction between the start and end points of the segment and generates (plans) a rotation command such that there is no change in the normal direction between the start and end points of the segment. In the second embodiment, the rotation command generation unit 344 determines that the workpiece normal direction at the current measurement point is the reference vector N b Rotation commands are generated as needed to maintain parallelism with the reference vector N. In other words, in the second embodiment, by rotating the workpiece with the rotation drive mechanism 230, the direction of the workpiece normal at the measurement point is always the reference vector N. b It can also be said that the orientation of the workpiece normal is constrained (bound) so that it is parallel to the workpiece.

[0068] For example, as illustrated in Figure 13, the normal direction of the workpiece surface changes moment by moment even while tracing a single segment. The rotation command generation unit 344 extracts information on the workpiece normal vector (current normal direction) Ni at the current measurement point from the measurement command data as needed (or at a predetermined control cycle pitch) based on position information obtained in real time from the counter unit 330. Then, it extracts the workpiece normal vector Ni and the reference vector N at the current measurement point. b The angle between them is denoted by Δθp(Ni;Nb). At this time, the rotation command ωi is set as follows:

[0069] ωi = Δθi(Ni;Nb) / tc

[0070] Currently, tc is, for example, a predetermined control cycle pitch.

[0071] Once the rotation command is determined in this way, the subsequent processing can be carried out in the same manner as in the first embodiment. The translation vector command correction unit 343 corrects the translation vector command Vf generated by the translation vector command generation unit 342 to compensate for the rotation of the rotation drive mechanism 230, and then corrects the translation vector command Vf AMD Generates. The translational movement mechanism 220 and the rotational drive mechanism 230 are driven by the corrected translational vector command and rotational command generated in this manner. During the tracing measurement, the normal direction of the workpiece surface at the measurement point does not change. For example, if the stylus 433 is approached perpendicular to the workpiece surface at the initial starting point, the stylus 433 will always be perpendicular to the workpiece surface during subsequent tracing measurements.

[0072] While the first and second embodiments may be implemented independently, combining them yields better results. In the first embodiment, rotation commands for each segment are planned to some extent, and the relative orientation between the workpiece normal and the probe measurement axis is controlled at the start and end points of the segment. By combining this with the second embodiment, the relative orientation between the workpiece and the probe 400 is finely controlled (adjusted) as needed based on the workpiece normal at the actual measurement point. This is to respond to minute changes in the workpiece surface (workpiece normal direction) within the segment and also serves to fine-tune to actual driving errors.

[0073] (Variation 1) As illustrated in Figure 14, probes 400 with a rotating shaft (rotation drive shaft) are known. Figure 14 illustrates a probe 400 with two rotation axes, but there is also a probe 400 with only one rotation axis. In this invention, a probe 400 having such a rotation axis may be used. In this case, a rotary table for rotating the workpiece may or may not be present. Furthermore, as a variation of the combination, a probe 400 with one rotation axis may be used in combination with a rotary table mechanism. Of course, a probe 400 with two rotation axes may be used in combination with a tilting rotary table mechanism. Even if there are multiple rotation axes, and regardless of the positional configuration of the combination of rotation axes and translation axes, it is possible to generate rotation commands and correct translation vector commands.

[0074] (Modification 2) The probe 400 is not limited to the surface roughness measurement unit 400. For probes 400 of the type where the relative orientation of the probe 400 with respect to the workpiece surface (relative orientation of the probe measurement axis) affects the detection accuracy, it is expected that the measurement accuracy will be greatly improved by applying the present invention. One example of such a probe 400 is a uniaxial probe 400 that has a detection function only in one dimension along a single measurement axis. The surface roughness measurement unit 400 illustrated in the above embodiment can also be considered an example of a uniaxial probe 400 that has a detection function only in one dimension. In addition, for example, contact-type sensors include electric micrometers (which come in linear and lever types), and non-contact types include so-called laser probes, chromatic point sensors (CPS), and capacitive non-contact sensors (which can be broadly called non-contact surface shape sensors). These uniaxial probes have high detection resolution and accuracy. However, it is necessary to adjust their relative orientation to the workpiece surface. In this respect, it is expected that the application of the present invention will make these high-precision sensors easier to use and improve measurement accuracy.

[0075] The probe 400 applicable to the present invention is not limited to a probe with a so-called single measurement axis. For example, a probe 400 of the type that has a spherical measuring tip (contact) at its tip and presses it against a workpiece, and detects the three-dimensional displacement of the measuring tip (stylus) with a probe sensor, may also be used. In other words, it is a probe 400 having a measuring element at the tip of a long shaft. The measuring element may be either contact-type or non-contact-type. Even in this case, for example, as illustrated in Figure 15, when measuring the shape of a curved workpiece such as an aircraft turbine blade with a large change in curvature, if the orientation of the probe 400 and the workpiece can be controlled (adjusted) so that the stylus is always oriented parallel to the normal direction of the workpiece, interference between the stylus and the workpiece can be prevented while the probe 400 measures around the workpiece.

[0076] It should be noted that the present invention is not limited to the embodiments described above, and can be modified as appropriate without departing from the spirit of the invention. The minimum configuration of a moving mechanism (translational movement mechanism, rotational drive mechanism) may include a case where the translational movement mechanism has one translational axis and the rotational drive mechanism has one rotational drive axis.

[0077] The following additional information is disclosed regarding the embodiments described above.

[0078] (Note 1) A shape measuring device that moves a probe and a workpiece relative to each other using a translational movement mechanism and a rotational drive mechanism, and measures the workpiece by tracing it along a preset tracing path, The rotational drive mechanism is driven and controlled in synchronization with the relative movement of the probe and the workpiece by the translational movement mechanism so that the angle between the probe and the workpiece surface becomes a desired angle. A shape measuring device characterized by the following features.

[0079] (Note 2) In the shape measuring device described in Appendix 1, A translation vector command generation unit generates a translation vector command for driving and controlling the translational movement mechanism so that the probe moves along the tracing path, A rotation command generation unit generates a rotation command to the rotation drive mechanism so that the angle between the probe and the work surface becomes a desired angle, A translation vector command correction unit corrects the translation vector command to compensate for the rotation command and generates a corrected translation vector command, The system includes a drive control unit that drives and controls the translational movement mechanism based on the corrected translational vector command, and drives and controls the rotational drive mechanism based on the rotation command, and drives and controls the translational movement mechanism and the rotational drive mechanism so that they are synchronized. A shape measuring device characterized by the following features.

[0080] (Note 3) In the shape measuring device described in Appendix 1, The rotational drive mechanism is driven and controlled so that the angle between the measurement axis of the probe and the workpiece surface becomes a desired angle. A shape measuring device characterized by the following features.

[0081] (Note 4) In the shape measuring device described in Appendix 1, The probe has an elongated shape, The rotational drive mechanism is driven and controlled so that the angle between the longitudinal axis direction of the probe and the workpiece surface becomes a desired angle. A shape measuring device characterized by the following features.

[0082] (Note 5) In the shape measuring device described in Appendix 2, The rotation command generation unit obtains information on the workpiece normal direction at each measurement point, either directly or indirectly, from the workpiece normal direction information included in the design data of the tracing path. A shape measuring device characterized by the following features.

[0083] (Note 6) In the shape measuring device described in Appendix 2, The system includes a speed pattern planning unit that divides the aforementioned route into multiple segments and generates a speed pattern plan by setting a speed pattern suitable for each segment. The rotation command generation unit, For each segment, the inter-segment normal angle is determined by finding the angle between the normal to the work surface at the starting point of the segment and the normal to the work surface at the ending point of the segment. For each segment, the rotation command is generated so as to cancel out the inter-segment normal angles. A shape measuring device characterized by the following features.

[0084] (Note 7) In the shape measuring device described in Appendix 2, It includes a reference direction setting unit for setting the reference direction, The rotation command generation unit, As the current measurement point, the coordinate values ​​of the workpiece surface currently being measured by the probe are acquired in real time. Based on the coordinate values ​​of the current measurement point, the normal direction of the workpiece surface at the current measurement point is determined. The rotation command is generated so as to cancel out the angle between the reference direction and the current normal direction. A shape measuring device characterized by the following features.

[0085] (Note 8) In the shape measuring device described in Appendix 1, The desired angle between the probe and the workpiece surface is a right angle. A shape measuring device characterized by the following features.

[0086] (Note 9) In the shape measuring device described in Appendix 1, The probe is a one-dimensional probe having a detection function in a one-dimensional direction along a single measurement axis. A shape measuring device characterized by the following features.

[0087] (Note 10) In the shape measuring device described in Appendix 1, The probe is a surface roughness measuring unit having a stylus that moves along the surface of the workpiece and a displacement detection unit that detects the displacement of the stylus in a direction perpendicular to the surface of the workpiece. A shape measuring device characterized by the following features.

[0088] (Note 11) A control method for a shape measuring device in which a probe and a workpiece are moved relative to each other by a translational movement mechanism and a rotational drive mechanism, and the probe traces and measures the workpiece along a preset tracing path, The rotational drive mechanism is driven and controlled in synchronization with the relative movement of the probe and the workpiece by the translational movement mechanism so that the angle between the probe and the workpiece surface becomes a desired angle. A control method for a shape measuring device, characterized by the following:

[0089] (Note 12) A control method for the shape measuring device described in Appendix 11, A translation vector command is generated to drive and control the translational movement mechanism so that the probe moves along the tracing path. A rotation command is generated for the rotation drive mechanism so that the angle between the probe and the workpiece surface becomes a desired angle. The translation vector command is corrected to compensate for the rotation command, and a corrected translation vector command is generated. The translational movement mechanism is driven and controlled based on the corrected translational vector command, and the rotational drive mechanism is driven and controlled based on the rotation command, so that the translational movement mechanism and the rotational drive mechanism are driven and controlled in a synchronized manner. A control method for a shape measuring device, characterized by the following:

[0090] (Note 13) In the control method for the shape measuring device described in Appendix 11, When measuring the aforementioned workpiece by tracing, only one translation drive shaft of the translational movement mechanism and one rotation drive shaft of the rotational drive mechanism are driven simultaneously. A control method for a shape measuring device, characterized by the following:

[0091] (Note 14) In the control method for the shape measuring device described in Appendix 11, The probe is supported by the translational movement mechanism so as to move solely by the translational movement mechanism, and the workpiece is supported so as to rotate at least by the rotational drive mechanism. The probe's orientation remains unchanged, and the normal direction of the workpiece at each measurement point is maintained in the same direction. A control method for a shape measuring device, characterized by the following:

[0092] (Note 15) A computer is incorporated into a shape measuring device that moves a probe and a workpiece relative to each other using a translational movement mechanism and a rotational drive mechanism, and measures the workpiece by tracing it along a preset tracing path. This computer, The control unit functions to drive and control the rotational drive mechanism so that the angle between the probe and the workpiece surface becomes a desired angle, in synchronization with the relative movement of the probe and the workpiece by the translational movement mechanism. A measurement and control program characterized by the following:

[0093] (Note 16) In the measurement control program described in Appendix 15, The aforementioned computer, A translation vector command generation unit generates a translation vector command for driving and controlling the translational movement mechanism so that the probe moves along the tracing path, A rotation command generation unit generates a rotation command to the rotation drive mechanism so that the angle between the probe and the work surface becomes a desired angle, A translation vector command correction unit corrects the translation vector command to compensate for the rotation command and generates a corrected translation vector command, A drive control unit that drives and controls the translational movement mechanism based on the corrected translational vector command, and drives and controls the rotational drive mechanism based on the rotation command, so that the translational movement mechanism and the rotational drive mechanism are driven in sync. A measurement and control program characterized by the following: [Explanation of Symbols]

[0094] 100 Shape Measurement System 200 Coordinate measuring machine 210 Surface plate 220 Translation mechanism 221 Y-slider 222 X Slider 223 Z-axis column 224 Z spindle 400 probes 400 Surface roughness measurement unit 410 Stylus Unit 420 Case Body 421 Torso 422 Nose section 423 Skid 424 Through hole 430 Stylus lever 431 Swivel lever 432 Leaf spring 433 stylus 440 Displacement detection unit 441 Ferrite plate 442 Inductance Detector 450 Outer casing 460 joints 230 Rotary drive mechanism 300 Motion Controllers 310 Measurement command acquisition section 330 Counter section 340 Drive command generation unit 341 Speed ​​Pattern Planning Department 342 Translation Vector Command Generation Unit 343 Translation Vector Command Correction Unit 344 Rotation command generation unit 345 Reference vector setting unit (reference direction setting unit) 350 Drive control unit 351 Translational Movement Mechanism Control Unit 352 Rotary drive mechanism control unit 500 host computers 511 CPU 520 Storage section 530 Shape analysis section

Claims

1. A shape measuring device that moves a probe and a workpiece relative to each other using a translational movement mechanism and a rotational drive mechanism, and measures the workpiece by tracing it along a preset tracing path, The rotational drive mechanism is driven and controlled in synchronization with the relative movement of the probe and the workpiece by the translational movement mechanism so that the angle between the probe and the workpiece surface becomes a desired angle. A shape measuring device characterized by the following features.

2. In the shape measuring device according to claim 1, A translation vector command generation unit generates a translation vector command for driving and controlling the translational movement mechanism so that the probe moves along the tracing path, A rotation command generation unit generates a rotation command to the rotation drive mechanism so that the angle between the probe and the work surface becomes a desired angle, A translation vector command correction unit corrects the translation vector command to compensate for the rotation command and generates a corrected translation vector command, The system includes a drive control unit that drives and controls the translational movement mechanism based on the corrected translational vector command, and drives and controls the rotational drive mechanism based on the rotation command, so that the translational movement mechanism and the rotational drive mechanism are driven in sync. A shape measuring device characterized by the following features.

3. In the shape measuring device according to claim 1, The rotational drive mechanism is driven and controlled so that the angle between the measurement axis of the probe and the workpiece surface becomes a desired angle. A shape measuring device characterized by the following features.

4. In the shape measuring device according to claim 1, The probe has an elongated shape, The rotational drive mechanism is driven and controlled so that the angle between the longitudinal axis direction of the probe and the workpiece surface becomes a desired angle. A shape measuring device characterized by the following features.

5. In the shape measuring device according to claim 2, The rotation command generation unit obtains information on the workpiece normal direction at each measurement point, either directly or indirectly, from the workpiece normal direction information included in the design data of the tracing path. A shape measuring device characterized by the following features.

6. In the shape measuring device according to claim 2, The system includes a speed pattern planning unit that divides the aforementioned route into multiple segments and generates a speed pattern plan by setting a speed pattern suitable for each segment. The rotation command generation unit, For each segment, the inter-segment normal angle is determined by finding the angle between the normal to the work surface at the starting point of the segment and the normal to the work surface at the ending point of the segment. For each segment, the rotation command is generated so as to cancel out the inter-segment normal angles. A shape measuring device characterized by the following features.

7. In the shape measuring device according to claim 2, It includes a reference direction setting unit for setting the reference direction, The rotation command generation unit, As the current measurement point, the coordinate values ​​of the workpiece surface currently being measured by the probe are acquired in real time. Based on the coordinate values ​​of the current measurement point, the normal direction of the workpiece surface at the current measurement point is determined. The rotation command is generated so as to cancel out the angle between the reference direction and the current normal direction. A shape measuring device characterized by the following features.

8. In the shape measuring device according to claim 1, The desired angle between the probe and the workpiece surface is a right angle. A shape measuring device characterized by the following features.

9. In the shape measuring device according to claim 1, The probe is a one-dimensional probe having a detection function in a one-dimensional direction along a single measurement axis. A shape measuring device characterized by the following features.

10. In the shape measuring device according to claim 1, The probe is a surface roughness measuring unit having a stylus that moves along the surface of the workpiece and a displacement detection unit that detects the displacement of the stylus in a direction perpendicular to the surface of the workpiece. A shape measuring device characterized by the following features.

11. A control method for a shape measuring device in which a probe and a workpiece are moved relative to each other by a translational movement mechanism and a rotational drive mechanism, and the probe traces and measures the workpiece along a preset tracing path, The rotational drive mechanism is driven and controlled in synchronization with the relative movement of the probe and the workpiece by the translational movement mechanism so that the angle between the probe and the workpiece surface becomes a desired angle. A control method for a shape measuring device, characterized by the following:

12. A control method for a shape measuring device according to claim 11, A translation vector command is generated to drive and control the translational movement mechanism so that the probe moves along the tracing path. A rotation command is generated for the rotation drive mechanism so that the angle between the probe and the workpiece surface becomes a desired angle. The translation vector command is corrected to compensate for the rotation command, and a corrected translation vector command is generated. The translational movement mechanism is driven and controlled based on the corrected translational vector command, and the rotational drive mechanism is driven and controlled based on the rotation command, so that the translational movement mechanism and the rotational drive mechanism are driven and controlled in a synchronized manner. A control method for a shape measuring device, characterized by the following:

13. In the control method for a shape measuring device according to claim 11, When measuring the aforementioned workpiece by tracing, only one translation drive shaft of the translational movement mechanism and one rotation drive shaft of the rotational drive mechanism are driven simultaneously. A control method for a shape measuring device, characterized by the following:

14. In the control method for a shape measuring device according to claim 11, The probe is supported by the translational movement mechanism so as to move solely by the translational movement mechanism, and the workpiece is supported so as to rotate at least by the rotational drive mechanism. The probe's orientation remains unchanged, and the normal direction of the workpiece at each measurement point is maintained in the same direction. A control method for a shape measuring device, characterized by the following:

15. A computer is incorporated into a shape measuring device that moves a probe and a workpiece relative to each other using a translational movement mechanism and a rotational drive mechanism, and measures the workpiece by tracing it along a preset tracing path. This computer, The control unit functions to drive and control the rotational drive mechanism so that the angle between the probe and the workpiece surface becomes a desired angle, in synchronization with the relative movement of the probe and the workpiece by the translational movement mechanism. A measurement and control program characterized by the following:

16. In the measurement control program according to claim 15, The aforementioned computer, A translation vector command generation unit generates a translation vector command for driving and controlling the translational movement mechanism so that the probe moves along the tracing path, A rotation command generation unit generates a rotation command to the rotation drive mechanism so that the angle between the probe and the work surface becomes a desired angle, A translation vector command correction unit corrects the translation vector command to compensate for the rotation command and generates a corrected translation vector command, A drive control unit that drives and controls the translational movement mechanism based on the corrected translational vector command, and drives and controls the rotational drive mechanism based on the rotation command, so that the translational movement mechanism and the rotational drive mechanism are driven in sync. A measurement and control program characterized by the following:

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