JP2018205092A - Evaluation device and method for evaluation - Google Patents

Abstract

To accurately evaluate the accuracy of processing a measurement object regardless of change in the shape of the measurement object or errors of a sensor part.SOLUTION: A first shape data acquisition part 711 determines the position of a sensor part 130 at a position Z1, and acquires first shape data by causing the sensor part 130 to measure the shape of a trench cross section Q1 of a trench 402. A second shape data acquisition part 712 determines the position of the sensor part 130 at a position Z2, and acquires one or plural pieces of second shape data by causing the sensor part 130 to continuously or intermittently measure the shape of a trench cross section Q2 of a trench 302 of a measurement object 300, which is moved in parallel to the center axis CZ of a stage 110. An evaluation part 713 evaluates the shape of the cross section at a position ZD based on the difference between the second shape data specified by the second shape data acquisition part 712 and the first shape data.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a technique for evaluating the shape of a groove of a measurement object in which the groove is spirally extended.

  For example, a high-weight and long rod-shaped workpiece having a length of 1 m and a diameter of 30 cm or more is processed by a cutting machine to form a spiral groove in the workpiece, and a workpiece such as a screw, propeller, drill, etc. Is being made. Such workpieces are evaluated for surface shape in order to prevent the production of defective products. For example, if the workpiece has a male-female structure that is fitted to the receiving workpiece, the workpiece is lifted from the cutting machine with a crane and fitted to the receiving workpiece, with a clearance gauge. Dozens of gaps are manually measured to evaluate the shape of the workpiece. Then, if there is a problem as a result of evaluating the shape, the workpiece is lifted again by the crane, installed in the cutting machine, and the problem portion is processed. The above is repeated, and finally a workpiece having a shape that satisfies the standard is manufactured. As described above, the conventional evaluation method has a problem that it takes a work day because the work is required to be transferred from the cutting machine using a crane. Therefore, a new evaluation method for solving this problem is desired.

  Against this background, Patent Document 1 discloses a technique for measuring the shape of a measurement object in which a groove extends in a spiral shape with high resolution and in a short time. Specifically, in Patent Document 1, the shape of the groove of the measurement object that moves around the central axis and moves in parallel with the central axis is measured by the sensor unit in a non-contact manner, and measurement data of the entire shape of the groove is obtained. A technique for obtaining the above is disclosed.

  Further, Patent Document 2 discloses a three-dimensional measurement method for accurately specifying a correction portion for a design value in a measurement object having an uneven surface such as a spherical lens. Specifically, in Patent Document 2, the X, Y, and Z coordinate values of an arbitrary region on the surface of a measurement object having a spherical surface are measured, and the difference between the measurement value of the measurement object and the spherical surface based on the design value is calculated. Thus, a technique for specifying a corrected portion is disclosed.

Japanese Patent Laying-Open No. 2015-145852 JP 2002-122423 A

  However, the methods of Patent Documents 1 and 2 do not take into account any sensor error that occurs in accordance with the installation environment such as the ambient temperature or measurement error that the sensor unit has in principle. Therefore, there is a problem that the processing accuracy of the shape of the measurement object cannot be correctly evaluated.

  Further, in the methods of Patent Documents 1 and 2, since any change in the shape of the measurement object due to thermal expansion or contraction is not taken into account, the measurement value of the measurement object is affected by this shape change. There is a problem that the processing accuracy of the measurement object cannot be correctly evaluated by simply comparing the value and the design value.

  An object of the present invention is to provide a technique that can accurately evaluate the processing accuracy of a measurement object regardless of an error in a sensor unit or a change in shape of the measurement object.

An evaluation apparatus according to an aspect of the present invention is an evaluation apparatus that evaluates the shape of a groove of a measurement object in which the groove is spirally extended,
A reference measurement object including a first groove having the same shape as a design value of a groove cross section perpendicular to the extending direction of the groove of the measurement object;
The first groove is configured to be movable between a first position for measuring the groove cross-sectional shape in a non-contact manner and a second position for measuring the groove cross-sectional shape of the measurement object in a non-contact manner. A sensor unit;
A moving unit for moving the measurement object in parallel with a central axis of the measurement object;
A first shape data acquisition unit that positions the sensor unit at the first position, causes the sensor unit to measure a shape of a groove cross section of the first groove, and acquires first shape data;
The sensor unit is positioned at the second position, and the shape of the groove section of the second groove, which is the groove of the measurement object moved by the moving unit in parallel with the central axis, is continuously or intermittently connected to the sensor unit. A second shape data acquisition unit that automatically measures and acquires one or more second shape data;
An evaluation unit that evaluates the shape of the second groove based on a difference between the first shape data and the one or more second shape data.

  According to this aspect, the reference measurement object including the first groove having the same shape as the design value of the groove cross section perpendicular to the extending direction of the groove of the measurement object is provided. Then, the shape of the groove cross section of the first groove is measured by the sensor unit to obtain the first shape data, and the shape of the groove cross section of the second groove of the measurement object is measured by the sensor unit to obtain the second shape data. Then, the shape of the second groove is evaluated from the difference between the first shape data and the second shape data.

  Therefore, even if there is a measurement error of the sensor unit due to the surrounding environment or a measurement error that the sensor unit has in principle, these measurement errors are included in both the first and second shape data. By obtaining the difference between the second shape data, these measurement errors are canceled out, and the processing accuracy of the second groove can be accurately evaluated.

  In addition, when there is a change in the shape of the measurement object due to thermal expansion or contraction, the reference measurement object also changes in shape in the same manner as the measurement object, so by obtaining the difference between the first and second shape data, This shape change component is canceled out, and the processing accuracy of the second groove can be accurately evaluated.

In the above aspect, the moving part includes a pair of support parts for supporting both ends of the measurement object,
When the reference measurement object is viewed from above downward, the extending direction of the first groove is parallel to the extending direction of the second groove, and the center line passes through the center of the reference measurement object in the thickness direction. The first intersection with the groove bottom line passing through the bottom of the first groove may be installed on one of the support portions so as to intersect the central axis.

  According to this aspect, when the reference measurement object is viewed from above to below, the extension direction of the first groove is parallel to the extension direction of the second groove and passes through the center of the reference measurement object in the thickness direction. The first intersection of the line and the groove bottom line passing through the bottom of the first groove is disposed on one support portion so as to intersect the central axis.

  Therefore, after the measurement of the first groove, it is possible to cause the sensor unit to reach the second position, which is the measurement position of the measurement object, simply by moving the sensor unit in parallel with the central axis. As a result, the complexity of positioning is eliminated and a more efficient measurement operation is possible.

  The said aspect WHEREIN: The said sensor part may measure the shape of the groove | channel cross section orthogonal to the extending direction of a said 1st groove | channel in a said 1st intersection.

  According to this aspect, the shape of the groove cross section orthogonal to the extending direction of the first groove is measured at the first intersection. Therefore, the sensor unit can measure the first groove having the same shape as the second groove.

In the above aspect, in the case where the second shape data acquisition unit measures the shape of the groove cross section at one position of the second groove, the measurement object is within the predetermined range based on the first position. Among the plurality of second shape data acquired by the sensor unit while moving in parallel with the axis, the second shape data with the smallest error from the first shape data is specified,
The evaluation unit may evaluate the shape of the groove cross section at the first position based on a difference between the specified second shape data and the first shape data.

  According to this aspect, the measurement object is moved in parallel with the central axis within a predetermined range corresponding to the position of 1 of the second groove, a plurality of second shape data is acquired, and an error from the first shape data Is determined, and the shape of the groove cross section at the position of 1 is evaluated based on the difference between the specified second shape data and the first shape data.

  Therefore, the measurement error due to the difference between the positional relationship between the optical axis and the second groove of the sensor unit positioned at the second position and the positional relationship between the optical axis and the first groove of the sensor unit positioned at the first position. Since the second shape data having the smallest value is specified as the second shape data to be evaluated, the evaluation accuracy can be improved.

  In the above aspect, the second shape data acquisition unit may employ a least square error as the error.

  In this aspect, since the least square error is adopted, it is possible to accurately specify the second shape data having the smallest error from the first shape data.

In the above aspect, the second groove is a groove whose depth changes at a constant rate toward the extending direction.
A memory for storing a change amount of the depth with respect to the first shape data of each of the one or more second shape data calculated based on the one or more positions of the second groove and the ratio; Prepared,
The second shape data acquisition unit corrects each of the one or more second shape data so that the amount of change is removed from the one or more second shape data,
The evaluation unit may evaluate the shape of the second groove based on a difference between the one or more second shape data after correction and the first shape data.

  According to this aspect, a groove whose depth changes at a constant rate in the extending direction is employed as the second groove. And each 2nd shape data is correct | amended so that the variation | change_quantity of the depth according to each position of a 2nd groove | channel is removed from each 2nd shape data. Thereby, the shape of the 2nd shape data after correction | amendment and the shape of 1st shape data can be evaluated equally, and the process precision of a 2nd groove | channel can be evaluated correctly.

In the above aspect, the sensor unit includes a plurality of sensor elements that measure the shape of the groove cross section at one position of the second groove divided into a plurality of regions,
At least one sensor element of the plurality of sensor elements is a first sensor element that measures a first region of the groove cross section in which an optical axis is shifted from a bottom of the groove cross section,
The second shape data acquisition unit
A first process for calculating a first approximation function indicating the shape of the first region from the first shape data measured by the first sensor element;
A second process of calculating a second approximate function by subtracting or adding the amount of change corresponding to the position of 1 of the second groove from the first approximate function;
The calculation of the distance between the first approximate function and the third intersection of the linear function indicating the optical axis and the fourth intersection of the second approximate function and the linear function is performed in parallel while maintaining the inclination of the linear function. A third process for calculating a plurality of distances by repeating the movement, and
A fourth process of correcting the second shape data by adding or subtracting the plurality of distances from the second shape data at the first position measured by the first sensor element may be executed.

  If the optical axis of the sensor section passes through the groove bottom of the groove cross section, the second shape data equivalent to the first shape data can be obtained by simply removing the variation corresponding to the position from the second shape data. . However, if the optical axis of the sensor part is deviated from the groove bottom of the groove cross section, the second shape data equivalent to the first shape data is obtained even if the amount of change corresponding to the position is simply removed from the second shape data. I can't get it.

  Therefore, in this aspect, the first shape data measured by the first sensor element in which the optical axis of the sensor unit is shifted from the groove bottom portion of the groove section is the shape of the first region of the groove section measured by the first sensor element. The second approximate function is calculated by subtracting or adding the amount of change corresponding to the position of 1 in the second groove from the first approximate function indicating. Then, while calculating the distance between the first approximate function and the third intersection of the linear function indicating the optical axis, and the fourth intersection of the second approximate function and the linear function, while moving the linear function while maintaining the inclination, Repeat to calculate multiple distances. Then, the second shape data is corrected by adding or subtracting a plurality of distances to the second shape data at one position. Therefore, the processing accuracy of the second groove can be accurately evaluated even if the optical axis of the sensor unit is deviated from the groove bottom (center) of the groove cross section.

  In the above aspect, the second shape data acquisition unit sets the first region to one or a plurality of sections so that an error between the first approximation function and the design value is equal to or less than a threshold range in the first process. One or a plurality of first approximation functions that divide and approximate the shape of each section may be calculated, and the second to fourth processes may be executed for each of the sections.

  According to this aspect, when the shapes of the first and second grooves are complicated, it is difficult to approximate the first region with one first approximation function. In this aspect, the first area is divided into a plurality of sections so that the error between the first approximation function and the design value is equal to or less than the threshold range, and the first approximation function is calculated for each section. Therefore, even if the shapes of the first and second grooves are complicated, the processing accuracy of the second groove can be accurately evaluated.

In the above aspect, the moving unit moves the measurement object in parallel with the central axis while rotating the measurement object about the central axis.
The second shape data acquisition unit sets the shape of the groove cross section of the second groove of the measurement object that is moved in parallel with the central axis while being rotated about the central axis by the moving unit to the sensor unit. A plurality of second shape data indicating the shape of the cross section of the groove at a plurality of positions of the second groove may be acquired by continuously or intermittently measuring.

  According to this aspect, the shape of the groove cross section of the second groove of the measurement object that is moved around the central axis while being rotated about the central axis is continuously or intermittently measured by the sensor unit, and the second groove is measured. A plurality of second shape data indicating the shape of the groove cross-section at the plurality of positions is acquired. Therefore, the processing accuracy of the shape of the entire area of the second groove can be evaluated.

  According to the present invention, it is possible to accurately evaluate the processing accuracy of the measurement object regardless of the error of the sensor unit or the shape change of the measurement object.

It is a whole lineblock diagram showing an example of an evaluation device in an embodiment of the invention. It is the figure which looked at the evaluation apparatus of FIG. 1 from upper direction to the downward direction. It is a figure which shows the evaluation apparatus at the time of seeing back from the front. It is a block diagram which shows an example of a structure of the evaluation apparatus which concerns on Embodiment 1 of this invention. It is a figure explaining the process in which 2nd shape data with the minimum difference | error with 1st shape data is specified from several 2nd shape data. It is a flowchart which shows the process of the evaluation apparatus which concerns on Embodiment 1 of this invention. It is a flowchart which shows the process of the evaluation apparatus which concerns on Embodiment 2 of this invention. It is a flowchart which shows the process of the evaluation apparatus which concerns on Embodiment 3 of this invention. It is a figure which shows the structure of the sensor part which concerns on Embodiment 4 of this invention. It is a graph for demonstrating the process which concerns on Embodiment 4 of this invention. In FIG. 10, it is a figure which shows the process which calculates | requires the distance of the intersection A and the intersection B, translating the linear function f3 (x). It is a figure explaining the process which divides | segments an area | region into a some area so that the error of approximate function f1 (x) and a design value may become below a threshold value range. In the evaluation apparatus which concerns on Embodiment 4, it is a graph which shows the measured value of the 2nd shape data in a certain position, and the 1st shape data after the correction | amendment with respect to the position. It is a flowchart which shows the process of the evaluation apparatus which concerns on Embodiment 5 of this invention.

(Embodiment 1)
FIG. 1 is an overall configuration diagram illustrating an example of an evaluation apparatus according to an embodiment of the present invention. FIG. 2 is a view of the evaluation apparatus of FIG. 1 as viewed from above. The evaluation apparatus is an apparatus for evaluating the shape of the groove 302 of the measuring object 300 in which the groove 302 (an example of the second groove) is formed in a spiral shape. The evaluation apparatus includes a pedestal unit 100, a stage 110 (an example of a moving unit), a support unit 120 (an example of a moving unit), a sensor unit 130, an attachment unit 140, and a ceiling unit 150.

  In FIG. 1, the Z direction indicates the longitudinal direction of the measurement object 300, the + Z direction indicates the front in the longitudinal direction, and the −Z direction indicates the rear in the longitudinal direction. Further, the Y direction indicates the vertical direction, the + Y direction indicates the upper direction, and the -Y direction indicates the lower direction. Further, the X direction indicates the left-right direction perpendicular to the Y direction and the Z direction, the + X direction indicates the right side when viewed from the rear, and the −X direction indicates the left side when viewed from the rear.

  As the measurement object 300, for example, a screw, a propeller, a drill, or the like is employed.

  The pedestal portion 100 is, for example, a flat plate shape and is fixed with respect to the ground. The stage 110 is attached to the pedestal unit 100 so as to be movable in the + Z direction and the −Z direction, that is, movable in the longitudinal direction of the measurement object 300.

  For example, a guide groove (not shown) is provided on the upper surface of the pedestal portion 100 along the Z direction, and a roller (not shown) that fits into the guide groove is provided on the bottom surface of the stage 110. Thereby, the stage 110 can move along the Z direction on the pedestal portion 100 by the roller being guided along the guide groove.

  A pair of support portions 120 are erected on both ends of the stage 110 in the Z direction. The support part 120 on the −Z direction side supports the end part 320 on the −Z direction side of the measurement object 300, and the support part 120 on the + Z direction side supports the end part 320 on the + Z direction side of the measurement object 300. Here, the pair of support parts 120 support the measurement object 300 such that the longitudinal direction of the measurement object 300 is parallel to the Z direction.

  Please refer to FIG. The measurement object 300 includes a measurement object region 310 in which a groove 302 is spirally formed, and a pair of end portions 320. Each of the pair of end portions 320 is a cylindrical member extending concentrically with the central axis CZ from the end portion on the Z direction side of the measurement target region 310.

  Please refer to FIG. The measurement object 300 is supported by a pair of support portions 120 so as to be rotatable about a central axis CZ in the longitudinal direction as a rotation axis. Specifically, each of the pair of support portions 120 includes a bearing (not shown) into which the end portion 320 is inserted, and supports the measurement object 300 through the bearings so as to be rotatable.

  The ceiling part 150 has a flat plate shape, for example, and is provided on the upper side of the pedestal part 100. An attachment part 140 is attached to the ceiling part 150 so as to be movable in the Z direction. For example, a guide groove (not shown) is provided in the ceiling portion 150 in parallel with the Z direction, and a roller (not shown) that fits in the guide groove is provided on the upper surface of the mounting portion 140. The mounting portion 140 can move in the Z direction with respect to the ceiling portion 150 with the roller guided in the guide groove.

  A sensor part 130 is detachably attached to the lower surface of the attachment part 140.

  The sensor unit 130 includes a three-dimensional image sensor that measures a three-dimensional shape of an object in a non-contact manner. Specifically, the sensor unit 130 includes a light source that irradiates measurement light to the groove 302 and a camera that receives reflected light from the groove 302. In the present embodiment, an optical cutting line is employed as the measurement light. However, this is only an example, and spot light may be employed as the measurement light instead of the light cutting line.

  The camera and the light source are arranged so that the optical axis of the camera and the optical axis of the light source have a predetermined apex angle. Therefore, the shape of the groove 302 can be measured by applying the principle of triangulation using the coordinates and apex angle of the measurement light appearing in the image captured by the camera.

  Please refer to FIG. The groove cross section Q2 is a surface showing the shape of the groove 302 when the groove 302 is cut along a surface orthogonal to the extending direction L21 of the groove 302. Therefore, the light source of the sensor unit 130 irradiates the light cutting line in a direction (width direction of the groove 302) orthogonal to the extending direction L21.

  The sensor unit 130 is positioned at a predetermined position Z1 (an example of the first position) above the reference measurement object 400 by the attachment unit 140, and the groove cross section Q1 of the groove 402 (an example of the first groove) of the reference measurement object 400. Measure the shape of the non-contact.

  Specifically, the sensor unit 130 measures the shape of the groove section Q1 orthogonal to the extending direction L11 of the groove 402 at the center (intersection P11) in the width direction of the groove section. Here, the position Z1 (FIG. 1) is disposed immediately above the center (intersection P11) in the width direction of the groove cross section. In the sensor unit 130, a light source is arranged so that a light cutting line is irradiated toward the center line L <b> 12 in the width direction of the reference measurement object 400. Therefore, by being positioned at the position Z1, the sensor unit 130 can measure the shape of the groove cross section Q1.

  The sensor unit 130 is positioned at a predetermined position Z2 (an example of a second position) above the measurement object 300 by the attachment unit 140, and the shape of the groove cross section Q2 of the groove 302 of the measurement object 300 is contactless. taking measurement.

  Please refer to FIG. The groove 402 of the reference measurement object 400 has the same shape as the design value of the groove cross section Q2. When viewed from above, the reference measurement object 400 includes a center line L12 in which the extending direction L11 of the groove 402 is parallel to the extending direction L21 of the groove 302 and passes through the center of the reference measurement object 400 in the thickness direction, and the groove An intersection P11 (an example of a first intersection) with the groove bottom line L13 passing through the bottom of 402 is installed on the upper surface of the support portion 120 on the + Z direction side so as to intersect with the central axis CZ.

  Further, the position Z2 (FIG. 1) is arranged at a certain position on the central axis CZ when the measuring object 300 is viewed from the upper side to the lower side. Therefore, after the sensor part 130 is positioned at the position Z1 and the shape of the groove cross section Q1 is measured, the groove section Q2 parallel to the groove cross section Q1 can be obtained simply by moving the sensor part 130 in the -Z direction and positioning it at the position Z2. Can be measured.

  In the present embodiment, it is assumed that the measurement object 300 is moved only in the Z direction and is not rotated around the central axis CZ. Therefore, the evaluation apparatus cannot measure the shape of the entire region of the groove 302 of the measurement object 300. Therefore, in the present embodiment, the evaluation apparatus measures the shape of, for example, one or several groove cross sections Q2. For example, if the groove cross section Q2 at a position (position ZD) of the groove 302 indicated by P21 is a measurement location, the intersection P21 (the width of the groove cross section Q2) between the groove bottom line L23 passing through the bottom of the groove 302 and the central axis CZ. When the center of the direction reaches just below the position P2, the sensor unit 130 may measure the shape of the groove cross section Q2.

  In the present embodiment, the groove cross section Q2 is processed at the same design value at any position. Therefore, it is possible to evaluate the processing accuracy of the groove 302 only by measuring the shape of one or several groove cross sections Q2 instead of the shape of the entire region of the groove 302.

  The evaluation device may be configured by a cutting machine. In this case, the evaluation apparatus becomes a cutting machine by replacing the sensor unit 130 with a machining blade. When cutting, a cylindrical workpiece is attached on the stage 110. Then, the attachment portion 140 to which the machining blade is attached is positioned at the position Z2, and then moves in the −Y direction to bring the machining blade into contact with the workpiece. The workpiece is moved in the −Z direction or the + Z direction by the stage 110 while being rotated about the central axis CZ by the support portion 120, whereby the spiral groove 302 is formed. Thereby, the measuring object 300 is processed.

  FIG. 3 is a diagram illustrating the evaluation device when viewed from the front to the rear. As shown in the left and right views, the support portion 120 includes a column portion 1202 that is erected on the stage 110 and a jig 1201 that is provided on the upper side of the column portion 1202. The reference measurement object 400 is placed on the upper surface of the jig 1201. Therefore, the width of the jig 1201 in the X direction is slightly larger than the width of the column part 1202.

  In the example of the left figure, the jig 1201 includes a semi-cylindrical hole 1203 that contacts the upper half of the end 320. Further, the jig 1201 is provided with a hole 1204 that comes into contact with the lower half of the end portion 320. The hole 1203 and the hole 1204 constitute a bearing by sandwiching the end portion 320.

  In the example of the right figure, a hole 1205 having a triangular cross section is formed on the lower surface of the jig 1201 in parallel with the Z direction. The column part 1202 in the right figure has the same configuration as the column part 1202 in the left figure. In the example of the right figure, after the end portion 320 is inserted into the hole 1204 of the column portion 1202, the jig 1201 is placed on the upper side of the column portion 1202 so as to sandwich the end portion 320 from the upper side of the column portion 1202.

  FIG. 4 is a block diagram showing an example of the configuration of the evaluation apparatus according to Embodiment 1 of the present invention. 4 includes a control unit 700, an operation unit 720, and a display unit 730 in addition to the stage 110, the support unit 120, the sensor unit 130, and the mounting unit 140 illustrated in FIG.

  The control unit 700 includes, for example, a processor such as a CPU, and includes a movement control unit 710, a first shape data acquisition unit 711, a second shape data acquisition unit 712, an evaluation unit 713, and a memory 714. Each block constituting the control unit 700 is realized by, for example, a processor executing a control program.

  The movement control unit 710 controls the stage 110, the support unit 120, and the attachment unit 140. Specifically, the movement control unit 710 moves the stage 110 in the Z direction by outputting a drive signal to a motor (not shown) that moves the stage 110 in the Z direction. As a result, the groove cross section Q2 at a predetermined position is positioned directly below the sensor unit 130 positioned at the position Z2.

  Further, the movement control unit 710 outputs a drive signal to a motor (not shown) that rotates the measurement object 300 about the central axis CZ, thereby rotating the measurement object 300 about the central axis CZ to the support unit 120. Let However, in the first embodiment, it is assumed that the measurement object 300 is not rotated around the central axis CZ. In addition, the movement control unit 710 moves the attachment unit 140 in the Z direction by outputting a drive signal to a motor (not shown) that moves the attachment unit 140 in the Z direction. Thereby, the sensor unit 130 is positioned at the position Z1 or the position Z2.

  The 1st shape data acquisition part 711 positions the sensor part 130 in the position Z1, makes the sensor part 130 measure the shape of the groove | channel cross section Q1 of the groove | channel 402, and acquires 1st shape data. Here, the first shape data is data indicating the height (depth) of each of a plurality of sample points on the groove section Q1 when a certain position in the Y direction is set as a reference height.

  The first shape data acquisition unit 711 acquires an image captured by the camera of the sensor unit 130, and applies the principle of triangulation to the coordinates of the light section line appearing in the image and the apex angles of the camera and the light source. The height data of each sample point is calculated, and the first shape data is acquired. As the coordinates of the light cutting line, for example, if the light cutting line extends in the horizontal direction of the image, the coordinate in the vertical direction is adopted. In this case, the first shape data acquisition unit 711 performs processing for setting a target line in parallel with the vertical direction with respect to an image in which a light section line appears and searching for coordinates where a luminance peak appears in the target line. By repeating while shifting in the horizontal direction, the coordinates of the light cutting line of each sample point may be specified.

  The 1st shape data acquisition part 711 should just position the sensor part 130 to the position Z1 by outputting the command which positions the sensor part 130 to the position Z1 to the movement control part 710. Receiving this command, the movement control unit 710 moves the attachment unit 140 to the position Z1, thereby positioning the sensor unit 130 at the position Z1.

  The second shape data acquisition unit 712 positions the sensor unit 130 at the position Z2, and continues to the sensor unit 130 the shape of the groove section Q2 of the groove 302 of the measurement target 300 that is moved in parallel with the central axis CZ by the stage 110. One or a plurality of second shape data is acquired by performing measurement periodically or intermittently.

  “Continuously measure” refers to causing the sensor unit 130 to measure the shape of the groove cross section Q2 by moving the measurement object 300 in the Z direction at a constant speed without being stopped. In this case, the second shape data acquisition unit 712 stores in advance the Z coordinate at which the groove cross-section Q2 to be measured is located in the measurement object 300, and when this Z coordinate reaches directly below the position Z2. In addition, the sensor section 130 may measure the groove cross section Q2.

  “Intermittently measuring” refers to temporarily stopping the measurement object 300 moved in the Z direction at a constant speed and causing the sensor unit 130 to measure the shape of the groove cross section Q2. In this case, the second shape data acquisition unit 712 temporarily stops the measurement object 300 when the Z coordinate stored in advance reaches just below the position Z2, and causes the sensor unit 130 to measure the shape of the groove cross section Q2. Just do it. In the following description, the second shape data acquisition unit 712 will be described as causing the sensor unit 130 to intermittently measure the shape of the groove cross section Q2.

  The second shape data acquisition unit 712 may move or stop the measurement object 300 on the stage 110 by appropriately outputting a command to the movement control unit 710. Further, the second shape data acquisition unit 712 may cause the sensor unit 130 to measure the shape of the groove cross section Q2 by appropriately outputting a command to the sensor unit 130. In addition, the second shape data acquisition unit 712 may output commands to the movement control unit 710 as appropriate so that the attachment unit 140 positions the sensor unit 130 at the position Z2.

  Similar to the first shape data, the second shape data is data indicating the height (depth) of each of a plurality of sample points on the groove cross section Q2 when a certain position in the Y direction is set as a reference height. Note that the details of the process of acquiring the second shape data by the second shape data acquisition unit 712 are the same as those of the first shape data acquisition unit 711, and thus the description thereof is omitted.

  When the second shape data acquisition unit 712 measures the shape of the groove cross section Q2 at the position ZD where the groove 302 is present, the second shape data acquisition unit 712 moves within a predetermined range based on the position ZD while the measurement object 300 moves in parallel with the central axis CZ. In addition, among the plurality of second shape data acquired by the sensor unit 130, the second shape data having the smallest error from the first shape data is specified. As the error, a least square error can be adopted. The least square error is expressed by Equation (1).

  i is an index that designates a sample point, and is an integer that takes values from i = 0 (index that designates one end of the groove section) to i = max (index that designates the other end of the groove section). . H1 (i) indicates the height data of the sample point (i) in the first shape data, and H2 (i) indicates the height data of the sample point (i) in the second shape data.

  Please refer to FIG. When the sensor unit 130 measures the groove cross section Q2, the optical cutting line may deviate from the groove cross section Q2. Examples of the deviation include a case where the center of the light section line is shifted from the width direction of the groove cross section Q2. This can also occur when the sensor unit 130 measures the groove cross section Q1. In this case, if the shift amount of the optical cutting line with respect to the groove section Q1 is different from the shift amount of the optical cutting line with respect to the groove section Q2, the first shape data and the second shape data cannot be accurately compared.

  Therefore, when measuring the groove cross section Q2, the second shape data acquisition unit 712 measures −Z (mm) from −δ (mm) centered on the position ZD (an example of the position of 1) on the groove 302 at the intersection P21. While the measurement object 300 moves within the range, the groove cross section Q2 is measured at a constant period, and a plurality of second shape data corresponding to the position ZD is acquired. Then, the second shape data acquisition unit 712 specifies second shape data having a minimum error from the first shape data among the plurality of second shape data corresponding to the position ZD. Note that δ and the fixed period are set to suitable values determined in advance based on the moving speed of the measurement object 300 and the required positioning accuracy, respectively.

  FIG. 5 is a diagram illustrating a process of identifying second shape data having a minimum error from the first shape data among a plurality of second shape data.

  In FIG. 5, a graph G1 shows the first shape data, graphs G20, G21,..., G2n,..., G2N show the second shape data, and a graph G25 shows the first shape data and the second shape data. And the least square error. In the graphs G1, G20, G21,..., G2n,..., G2N, G25, the vertical axis indicates the height data H (mm), and the horizontal axis indicates the position L (with respect to the width direction of the groove cross sections Q1 and Q2). mm).

  In the example of the graph G1, the first shape data shows that the center in the width direction of the groove cross section Q1 is located almost at the center of the position L, and the deviation of the optical section line from the groove cross section Q1 is small.

  The graph G20 shows the second shape data when the intersection point P21 is located at a position f0 that is -δ away from the position ZD. Graphs G21,..., G2n are respectively obtained at positions f1 (mm), f2 (mm),..., Fn (mm) where the intersection point P21 is a certain distance Δf away from the position f0 in the + Z direction. The second shape data is shown. The graph G2N shows the second shape data when the intersection P21 is located at a position fN that is separated by + δ with respect to the position ZD.

  The second shape data acquisition unit 712 is a least square error between the first shape data indicated by the graph G1 and the second shape data indicated by the graphs G20, G21,..., G2n,. Ask for. In the graph G25, the least square error at the positions f0, f1,..., Fn,. In this example, the least square error at the position fn was the smallest. Therefore, the second shape data at the position fn indicated by the graph G2n is determined as a comparison target with the first shape data. The second shape data shown in the graph G2n shows that the center in the width direction of the groove cross section Q2 is located almost at the center of the position L, the optical cutting line is less displaced from the groove cross section Q2, and the displacement from the groove cross section Q1 is also smaller. I understand that there are few. Thereby, the shape of 1st shape data and 2nd shape data can be evaluated correctly.

  Here, the second shape data having the minimum least square error is specified, but the present invention is not limited to this. The second shape data in which the position of the groove bottom portion most closely matches the first shape data may be specified.

  Please refer to FIG. The evaluation unit 713 evaluates the shape of the groove cross section at the position ZD based on the difference between the second shape data specified by the second shape data acquisition unit 712 and the first shape data. Here, the evaluation unit 713 obtains a difference between the height data corresponding to the sample points in the first shape data and the second shape data, and calculates a statistical value (for example, an average value) of the difference. The evaluation value of the difference between the first shape data and the second shape data may be calculated. Then, the evaluation unit 713 determines that the groove cross section Q2 at the position ZD is normal if the evaluation value is equal to or less than the predetermined evaluation reference value, and if the evaluation value exceeds the evaluation reference value, the groove cross section Q2 at the position ZD. May be determined as abnormal. If there are a plurality of positions ZD of the groove cross section Q2 to be evaluated, the evaluation unit 713 obtains an evaluation value for each of the plurality of positions ZD. And the evaluation part 713 should just determine with the shape of the groove | channel 302 of the measuring object 300 being normal, for example, if all the evaluation values are below an evaluation reference value.

  The operation unit 720 is configured by an input device such as a keyboard and a mouse, for example, and accepts various operations from the operator. Various operations include an instruction to start measurement.

  The display unit 730 is configured with a display device such as a liquid crystal display, for example, and displays the evaluation result of the evaluation unit 713 and the like. The display unit 730 may display various graphs shown in FIG.

  FIG. 6 is a flowchart showing processing of the evaluation apparatus according to Embodiment 1 of the present invention. In S <b> 601, the first shape data acquisition unit 711 outputs a command for moving the sensor unit 130 to the position Z <b> 1 to the movement control unit 710. Thereby, the movement control part 710 positions the attachment part 140 in the position Z1, and positions the sensor part 130 in the position Z1.

  In S <b> 602, the first shape data acquisition unit 711 causes the sensor unit 130 to measure the reference measurement object 400 and acquires the first shape data.

  In step S <b> 603, the second shape data acquisition unit 712 outputs a command for moving the sensor unit 130 to the position Z <b> 2 to the movement control unit 710. Thereby, the movement control part 710 positions the attachment part 140 in the position Z2, and positions the sensor part 130 in the position Z2. Here, it is assumed that the position Z2 is determined in advance so that the position ZD (FIG. 2) to be measured is located directly below.

  In step S604, the second shape data acquisition unit 712 moves the measurement object 300 in the + Z direction or the −Z direction at a constant speed in the range of + δ to −δ around the position ZD, while causing the sensor unit 130 to move at a constant cycle. The groove cross section Q2 is measured, and a plurality of second shape data corresponding to the position ZD is acquired.

  Here, as the aspect of S604, an aspect may be employed in which the position ZD is first positioned directly below the position Z2, and then the measurement object 300 is moved in the range of −δ to + δ. Alternatively, if the position Z2 is determined so that the position: ZD-δ is located immediately below the position Z2, the measurement object 300 is moved in the + Z direction from the position: ZD-δ to the position: ZD + δ. Aspects may be employed. Alternatively, if the position Z2 is determined so that the position: ZD + δ is positioned directly below the position Z2, the measurement object 300 is moved in the −Z direction from the position: ZD + δ to the position: ZD−δ. May be adopted.

  In S605, the second shape data acquisition unit 712 compares the first shape data with a plurality of second shape data corresponding to the position ZD.

  In S606, the second shape data acquisition unit 712 specifies second shape data having the smallest error in the first shape data among the plurality of second shape data corresponding to the position ZD.

  In S607, the evaluation unit 713 calculates a difference between the first shape data and the second shape data specified in S606. Then, the evaluation unit 713 calculates an evaluation value based on the calculated difference, and evaluates the shape of the groove cross section Q2.

  As described above, in the evaluation apparatus according to Embodiment 1, even if there is a measurement error of the sensor unit 130 due to the surrounding environment or a measurement error that the sensor unit 130 has in principle, these measurement errors are the first and second. Since it is included in both of the shape data, by obtaining the difference between the first and second shape data, these measurement errors are offset, and the processing accuracy of the second groove can be accurately evaluated.

  In addition, when the shape of the measurement object 300 is changed due to thermal expansion or contraction, the reference measurement object 400 is also changed in shape similarly to the measurement object, and thus the difference between the first and second shape data is obtained. Thus, the component of the shape change is canceled out, and the processing accuracy of the second groove can be accurately evaluated.

  In FIG. 6, the processes of S604 to S606 may be omitted. In FIG. 6, when measuring the groove cross-section Q2 at a plurality of positions ZD, when the processing of S603 to S607 for one position ZD is completed, the second shape data acquisition unit 712 performs the next measurement immediately below the position Z2. A command for moving the measurement object 300 in the Z direction so as to reach the position ZD, which is a position, may be output to the movement control unit 710.

(Embodiment 2)
The evaluation apparatus according to Embodiment 2 evaluates the shape of the groove cross section Q2 in the entire region of the groove 302 by moving the measurement object 300 in the Z direction while rotating around the central axis CZ. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  Please refer to FIG. If the measurement object 300 is rotated around the central rotation axis CZ without moving in the Z direction, the groove section Q2 appears to move in the Z direction from the sensor unit 130. In the example of FIG. 1, the measuring object 300 has the extending direction L <b> 21 facing the diagonally upper left direction. Therefore, when the measuring object 300 is rotated counterclockwise as indicated by the arrow when viewed in the + Z direction, the sensor unit 130. Therefore, the groove cross section Q2 appears to move in the + Z direction. Further, when the measuring object 300 is rotated in the clockwise direction opposite to the arrow when viewed in the + Z direction, the groove cross section Q2 appears to move in the −Z direction.

  Therefore, when the measuring object 300 is moved in the Z direction so as to cancel the movement of the groove section Q2, the groove section Q2 appears to be stationary from the sensor unit 130. For example, when the measurement object 300 is rotated counterclockwise as indicated by an arrow, the groove cross section Q2 moves in the + Z direction at the movement speed V when viewed from the sensor unit 130. Therefore, the measurement object 300 is moved in the −Z direction. When moved at the moving speed V, the groove cross section Q2 appears to be stationary as viewed from the sensor unit 130. On the other hand, when the measurement object 300 is rotated clockwise, the groove cross section Q2 moves at the movement speed V in the −Z direction when viewed from the sensor unit 130. Therefore, the measurement object 300 moves in the + Z direction at the movement speed V. , The groove cross section Q2 appears to be stationary as viewed from the sensor unit 130.

  Therefore, while rotating the measuring object 300 around the central axis CZ, the measuring object 300 is moved in the Z direction so that the movement of the groove cross section Q2 is canceled. Thereby, the stationary sensor unit 130 can always irradiate the groove section Q2 with the light cutting line, and can continuously measure the shape of the groove section Q2 at an arbitrary position by photographing the light cutting line continuously.

  In the present embodiment, the same values as the angular velocity and the moving speed when the measuring object 300 is processed are adopted as the angular velocity and the moving speed of the measuring object 300 in the Z direction.

  FIG. 7 is a flowchart showing processing of the evaluation apparatus according to Embodiment 2 of the present invention. S701 to S703 are the same as S601 to S603 in FIG.

  In S704, the second shape data acquisition unit 712 outputs a command to the movement control unit 710 so that the position ZD where the groove cross section Q2 to be measured reaches directly below the position Z2. Receiving this command, the movement control unit 710 rotates the measurement object 300 by a predetermined angle around the central axis CZ and moves it by a predetermined distance in the Z direction to reach the position ZD directly below the position Z2.

  S705 to S708 are the same as S604 to S607 in FIG. In S709, it is determined whether or not the measurement of the entire area of the groove 302 has been completed. If the measurement of the entire area has been completed, the process ends. On the other hand, if the measurement of the entire area of the groove 302 has not been completed, the process returns to S704.

  That is, by repeating the loop of S704 to S709, measurement is performed from the position ZD located closest to one end 320 side of the measurement object 300 to the position ZD located closest to the other end 320. The object 300 is rotated by a predetermined angle around the central axis CZ and moved by a predetermined distance in the Z direction, so that the position ZD is intermittently positioned directly below the position Z2. Further, every time the position ZD is positioned directly below the position Z2, the measurement object 300 is moved in the Z direction in the range of −δ to + δ, and the second shape data with the smallest error from the first shape data is obtained. Identified. Thus, the shape of the groove cross section Q2 at the plurality of positions ZD in the entire region of the groove 302 is evaluated. As a result, in the present embodiment, the shape of the groove 302 can be more accurately evaluated.

  In the flowchart of FIG. 7, the measurement object 300 is intermittently rotated around the central axis CZ and moved to the Z axis, but may be continuously performed. In this case, the processes of S706 and S707 may be omitted. In S705, one second shape data corresponding to the position ZD may be measured without moving the measurement object 300 in the Z direction within the range from −δ to + δ.

(Embodiment 3)
The evaluation apparatus according to Embodiment 3 evaluates the shape of the groove 302 in the measurement object 300 in which the depth of the groove 302 changes at a constant rate U in the extending direction.

  Please refer to FIG. The memory 714 stores the amount of change in depth of each of the one or more second shape data calculated based on the one or more positions ZD and the ratio U of the groove 302 with respect to the first shape data. In the present embodiment, the position ZD0 of the measurement object 300 where there is no difference in the depth between the reference measurement object 400 and the groove 302 and one of the measurement objects 300 where there is a difference in the depth between the reference measurement object 400 and the groove 302 or A plurality of positions ZD1 are measured. Therefore, the memory 714 stores the change amount of the groove 302 with respect to the groove 402 at the position ZD1. For example, it is assumed that the ratio U indicates the amount of change in depth per unit length in the extending direction L21 of the groove 302. In this case, the memory 714 calculates the amount of change in depth at the position ZD1 calculated in advance by multiplying the distance U of the groove 302 along the extending direction L21 from the position ZD0 to the position ZD1 by the ratio U. And stored in association with each other. In the present embodiment, it is assumed that the reference measurement object 400 is not rotated around the central axis CZ but is only moved in the Z direction.

  FIG. 8 is a flowchart showing the processing of the evaluation apparatus according to Embodiment 3 of the present invention. S801 to S807 are the same as S601 to S607 in FIG. However, in S803, it is assumed that the position Z2 is determined in advance so that the position ZD0 is located immediately below. Thus, in S801 to S807, the shape of the groove cross section Q2 at the position ZD0 where the amount of change in depth is 0 with respect to the reference measurement object 400 is evaluated.

  In S808, the second shape data acquisition unit 712 outputs a command for moving the measurement object 300 in the Z direction to the movement control unit 710 so that the position ZD1 is positioned directly below the position Z2. Receiving this command, the movement control unit 710 moves the stage 110 so that the position ZD1 is positioned directly below the position Z2.

  In S809, the second shape data acquisition unit 712 moves the measurement object 300 in the range of + δ to −δ around the position ZD1 at a constant speed in the + Z direction or the −Z direction, and moves the sensor unit 130 at a constant cycle. The groove cross section Q2 is measured, and a plurality of second shape data corresponding to the position ZD1 is acquired.

  In S810, the second shape data acquisition unit 712 reads the amount of change in depth corresponding to the position ZD1 from the memory 714, and removes the amount of change in depth for each of the plurality of second shape data acquired in S809. Thus, the second shape data is corrected. For example, if the groove cross-section Q2 at the position ZD1 is deeper than the groove cross-section Q1 by the amount of change d, the second shape data acquisition unit 712 uses the height data H (i) of each sample point of the second shape data. The second shape data may be corrected by adding the change amount d to. On the other hand, if the groove cross section Q2 at the position ZD1 is assumed to be higher than the groove cross section Q1 by the amount of change d, the second shape data acquisition unit 712 has height data H (i) of each sample point of the second shape data. The amount of change d may be subtracted from Thereby, the amount of change in depth with respect to the first shape data in the second shape data is removed, and the shape of the second shape data and the shape of the first shape data can be evaluated on an equal basis.

  In S811, the second shape data acquisition unit 712 compares the plurality of corrected second shape data with the first shape data.

  In S812, the second shape data acquisition unit 712 specifies second shape data having a minimum error with respect to the first shape data among the plurality of second shape data. Here, as described in the first embodiment, the least square error is used as the error.

  In S813, the evaluation unit 713 calculates an evaluation value based on the difference between the second shape data and the first shape data specified in S812, and evaluates the shape of the groove section Q2 at the position ZD1.

  As described above, in the evaluation apparatus according to Embodiment 3, the second shape data is corrected so that the amount of change in depth according to the position ZD1 of the groove 302 is removed from the second shape data. Thereby, the shape of the 2nd shape data after correction | amendment and the shape of 1st shape data can be evaluated equally, and the process precision of a 2nd groove | channel can be evaluated correctly.

  In addition, when acquiring the 2nd shape data of several position ZD1 in FIG. 8, after completion | finish of the process of S813, a process is returned to S808 so that the position ZD1 of the next measuring object may be located directly under the position Z2. The measuring object 300 may be moved in the Z direction. And the process of S809-S813 should just be performed.

(Embodiment 4)
In the fourth embodiment, the sensor unit 130 includes a plurality of sensor elements, and at least one of the plurality of sensor elements has an optical axis that is offset from the groove bottom of the groove 302. Further, in the fourth embodiment, as in the third embodiment, the measurement object 300 including the groove 302 whose depth changes at a certain rate U toward the extending direction L21 is an evaluation target. In the fourth embodiment, the amount of change in depth is accurately removed from the second shape data obtained by measuring the measurement object 300 by the sensor element whose optical axis is shifted.

  FIG. 9 is a diagram showing a configuration of the sensor unit 130 according to Embodiment 4 of the present invention. FIG. 9 shows a configuration of the sensor unit 130 when the sensor unit 130 is viewed from a direction orthogonal to the extending direction L21 of the groove 302. The sensor unit 130 includes three sensor elements 131, 132, and 133. The sensor elements 131 and 133 are examples of first sensor elements. The sensor elements 131, 132, and 133 measure the regions R91, R92, and R93 of the groove cross section Q2 at the position ZD where the groove 302 is located, respectively. Each of the sensor elements 131 to 133 includes a camera 91 and a light source 92. The camera 91 and the light source 92 are arranged so that the optical axes have a certain apex angle. The light source 92 emits a light cutting line. The camera 91 captures an image of the groove 302 irradiated with the light cutting line toward the groove cross section Q2.

  In each of the sensor elements 131, 132, and 133, light emission lines S91, S92, and S93 are connected to each other, and a light source 92 is disposed so as to irradiate the entire width of the groove section Q2. Accordingly, the sensor elements 131 to 133 can simultaneously measure the shape of the groove section Q2 at the same position ZD.

  The optical axes L91, L92, and L93 of the sensor elements 131, 132, and 133 are lines that equally divide the radiation surfaces S91, S92, and S93, respectively. In the sensor element 132, the optical axis L92 is parallel to the Y direction, and intersects the center O9 in the width direction of the groove cross section Q2. The optical axes L91 to L93 intersect at an intersection CP on the optical axis L92. At the intersection point CP, the sensor elements 131 to 133 are arranged so that the angle formed by the optical axis L91 and the optical axis L92 is equal to the angle formed by the optical axis L93 and the optical axis L92. The sensor elements 131 to 133 are arranged so that the lengths of the optical axes L91 to L93 from the light source 92 to the groove cross section Q2 are substantially equal to each other. Therefore, the regions R91, R92, and R93 divide the groove cross section Q2 into three equal parts.

  Here, since the optical axis L92 intersects the center O9, the sensor element 132 can remove the variation d from the second shape data even if the method described in the third embodiment is applied as it is.

  However, since the sensor elements 131 and 133 have the optical axes L91 and L93 deviated from the center O9 (since they are inclined with respect to the Y direction), if the method described in the third embodiment is applied as it is, The variation d cannot be removed from the shape data.

  Please refer to FIG. FIG. 10 is a graph for explaining the processing according to the fourth embodiment of the present invention. In FIG. 10, f1 (x) is an approximate function of the first shape data (an example of the first approximate function), and f2 (x) is an approximate function obtained by subtracting the variation d from f1 (x) (second An example of an approximate function), a linear function f3 (x) is a linear function indicating the optical axis L91 of the sensor element 131. In FIG. 10, the vertical axis (y-axis) indicates a direction parallel to the optical axis L92, and the horizontal axis (x-axis) indicates the width direction of the groove cross section Q1. The position of x = 0 indicates the groove bottom portion of the groove cross section Q1.

  In the sensor element 132, since the optical axis L92 (FIG. 9) is parallel to the y-axis, the direction of the change amount d is parallel to the y-axis. Therefore, if the depth change amount d with respect to the first shape data is added to the second shape data, the change amount d is removed from the second shape data.

  However, in the sensor element 131, the optical axis L91 is inclined with respect to the y-axis. Therefore, in the second shape data, in order to remove the amount of change in depth on the optical axis L91, it is necessary to reduce the distance between the intersection A and the intersection B parallel to the optical axis L91, not the amount of change d. is there. The intersection point A is the intersection point of the approximate function f1 (x) and the optical axis L91, and the intersection point B is the intersection point of the approximate function f2 (x) and the optical axis L91. The same applies to the sensor element 133.

  Therefore, in the present embodiment, the following processing is performed. In the following description, the optical axis L91 will be described as an example, but the optical axis L93 is the same.

  (1) From the arrangement of the sensor elements 131, a linear function representing the optical axis L91: f3 (x) = a · x + b is calculated. Here, since the linear function representing the optical axis L91 can be calculated in advance, the linear function calculated in advance is stored in the memory 714, and the second shape data acquisition unit 712 acquires the linear function from the memory 714. do it.

(2) The second shape data acquisition unit 712 acquires the first shape data by measuring the reference measurement object 400, extracts the range of the region R91 from the first shape data, and approximates the function f1 of the extracted first shape data. (X) is calculated. Here, a quadratic function of f1 (x) = α · x ² + β · x + γ is adopted as an approximate function of f1 (x).

(3) The second shape data acquisition unit 712 subtracts the depth change amount d at the measurement target position ZD from the approximate function f1 (x) calculated in (2) to obtain an approximate function f2 (x) = f1 ( x) -d is calculated. For example, the approximate function f2 (x) is represented by f2 (x) = α · x ² + β · x + γ−d. If the position ZD1 is higher than the position ZD0 by the depth change amount d, the second shape data acquisition unit 712 sets the approximate function f2 (x) to f2 (x) = f1 (x) + d, that is, f2. (X) = α · x ² + β · x + γ + d may be calculated.

  (4) The second shape data acquisition unit 712 includes the intersection A between the approximate function f1 (x) calculated in (2) and the linear function f3 (x), and the approximate function f2 (x) calculated in (3). An intersection point B with the linear function f3 (x) is calculated. Then, the second shape data acquisition unit 712 calculates the distance between the intersection A and the intersection B. The distance between the intersections A and B represents a distance parallel to the optical axis L91, and represents the error itself on the optical axis L91.

  (5) As shown in FIG. 11, the second shape data acquisition unit 712 calculates the distance in the entire region R91 by using the y-intercept of the linear function f3 (x) acquired in (1) in the region R91. The process of (4) is performed while changing so that the entire area is included.

  FIG. 11 is a diagram illustrating a process for obtaining the distance d (w) between the intersection A and the intersection B while translating the linear function f3 (x) in FIG. The linear function f3 (x) to be translated is set as f3 (x) = a · x + b + w. Here, w takes a value between −u and + u. -U indicates the offset of the y-intercept with respect to b when the linear function f3 (x) is translated at the left end of the region R91, and + u is when the linear function f3 (x) is translated at the right end of the region R91. The offset of the y-intercept with respect to b is shown.

  The second shape data acquisition unit 712 includes an intersection A (w) between f3 (x) = a · x + b + w and f1 (x), and an intersection B (w) between f3 (x) = a · x + b + w and f2 (x). A plurality of distances d (w) are calculated by repeating the calculation of the distance d (w) with the translation of the linear function f (x) while maintaining the inclination of the linear function f3 (x).

The intersection A (w) is obtained by solving the equation f1 (x) −a · x−b−w = 0, and the intersection B (w) is f2 (x) −a · x−b−w. Is obtained by solving the equation of = 0. The distance d (w) is the Euclidean distance between the intersections A (w) and B (w), that is, d (w) = ((xa−), where the intersection A is xa, ya and the intersection B is xb, yb. xb) ² + (ya−yb) ² ) ^1/2 .

  (6) The second shape data acquisition unit 712 corrects the second shape data by adding or subtracting the distance d (w) to the height data H (i) of each sample point of the second shape data. For example, if the groove cross-section Q2 at the position ZD is deeper than the groove cross-section Q1 by the amount of change d, the second shape data acquisition unit 712 uses the height data H of each sample point of the second shape data in the region R91. The second shape data may be corrected by adding the distance d (w) to (i). On the other hand, if the groove cross section Q2 at the position ZD is assumed to be higher than the groove cross section Q1 by a distance d (w), the second shape data acquisition unit 712 has a height of each sample point of the second shape data in the region R91. The second shape data may be corrected by subtracting the distance d (w) from the data H (i). Thereby, the correct shape data of the groove cross section Q2 is obtained by removing the influence of the depth variation from the second shape data.

  The processes (1) and (2) correspond to an example of the first process, the process (3) corresponds to an example of the second process, and the processes (4) and (5) correspond to an example of the third process. The process (6) corresponds to an example of a fourth process.

  The evaluation unit 713 evaluates the shape of the groove cross section Q2 by comparing the corrected second shape data with the first shape data.

  However, when the shapes of the groove cross-sections Q1 and Q2 are complicated, a large error may occur when the first shape data is expressed by using one approximate function for the entire region R91 in the process (2). . Therefore, in the present embodiment, the second shape data acquisition unit 712 sets one or a plurality of regions R91 so that the error between the approximate function f1 (x) and the design value falls within the threshold range in the process (2). 1 or a plurality of approximation functions f1 (x) that approximate the shape of each section are calculated, and processes (3) to (6) are executed for each section.

  FIG. 12 is a diagram illustrating a process of dividing the region R91 into a plurality of sections so that the error between the approximate function f1 (x) and the design value is equal to or smaller than the threshold range.

  A graph G1201 in FIG. 12 shows an error between the approximate function f1 (x) and the design value of the region R91 when the first shape data in the region R91 shown in FIG. 8 is approximated by one approximate function f1 (x). Yes. In the graph G1201, a curve g1 indicates a design value, a curve g2 indicates an error between the approximate function f1 (x) and the design value, and a curve g3 indicates a measurement value of the first shape data in the region R91. In the graph G1201, the left vertical axis indicates the height, the right vertical axis indicates the error between the approximate function f1 (x) and the design value, and the horizontal axis indicates each position in the region R91.

  In the graph G1201, the curve g2 protrudes from the threshold range Th, and it can be seen that there is a large error with respect to the design value of the approximate function f1. The threshold range Th is a predetermined allowable error range, has a constant value up and down around 0, and a suitable value is adopted from the required measurement accuracy.

  In the graph G1202, since the error can be contained within the threshold range Th using one approximation function f11 (x) in the section R11 from the right end position x0 to the position x1 of the region R91, the second shape data The acquisition unit 712 extracts the section R11 from the region R91 and adopts the approximate function f11 (x) as the approximate function f1 (x) for the section R11. That is, the second shape data acquisition unit 712 determines the section R11 as the application range of the approximate function f11 (x) because the error exceeds the threshold range Th when the position x1 is exceeded.

  In the graph G1203, in the section R12 from the position x1 to the position x2, using one approximation function f12 (x), the error can be within the threshold range Th, so the second shape data acquisition unit 712 The section R12 is extracted from the region R91, and the approximate function f12 (x) is adopted as the approximate function f1 (x) for the section R12. That is, the second shape data acquisition unit 712 determines the section R12 as the application range of the approximation function f12 (x) because the error exceeds the threshold range Th when the position x2 is exceeded.

  In the graph G1204, in the section R13 from the position x2 to the position x3, the error can be kept within the threshold range Th using one approximate function f13 (x). Therefore, the second shape data acquisition unit 712 The section R13 is extracted from the region R91, and the approximate function f13 (x) is adopted as the approximate function f1 (x) for the section R13. That is, the second shape data acquisition unit 712 determines the section R13 as the application range of the approximate function f13 (x) because the error exceeds the threshold range Th when the position x3 is exceeded.

  In the graph G1205, in the section R14 from the position x3 to the position x4 that is the left end of the region R91, the error can be within the threshold range Th using one approximation function f14 (x). The data acquisition unit 712 extracts the section R14 from the region R91 and adopts the approximate function f14 (x) as the approximate function f1 (x) for the section R14.

  Then, the second shape data acquisition unit 712 performs the above processes (3) to (5) in each of the sections R11 to R14, and obtains the distance d (w) for each sample point in the sections R11 to R14. Then, the second shape data acquisition unit 712 adds or subtracts the corresponding distance d (w) to the height data H (i) of each sample point of the second shape data in the region R91 to thereby add the second shape data. The influence of the distance d (w) is removed from the data (processing (6)). Accordingly, the evaluation unit 713 can perform comparison with the first shape data using the second shape data from which the influence of the depth change amount d is removed.

  In FIG. 12, an example for the region R91 is shown, but the same processing is applied to the region R93 shown in FIG. In the present embodiment, since there are two sensor elements whose optical axes are deviated from the center O9 of the groove cross section Q2, the processing shown in FIG. 12 is applied to the two first shape data. This is an example. That is, the process shown in FIG. 12 is applied to each sensor element if the optical axis is one or three or more sensor elements whose center is shifted from the center O9 of the groove section Q2.

  By the above method, it is possible to remove the influence of the change in the depth direction with high accuracy even for an object having a complicated curved surface shape.

  FIG. 13 is a graph showing measured values of the second shape data at a certain position ZD and corrected first shape data for the position ZD in the evaluation apparatus according to the fourth embodiment. The upper graph is a graph in the sensor element 131, the middle graph is a graph in the sensor element 132, and the lower graph is a graph in the sensor element 133.

  In each graph of FIG. 13, the vertical axis indicates the height, and the horizontal axis indicates each position of the groove cross section Q2. A point group g11 plotted with rhombus points shows the first shape data after correction, and a point group g12 plotted with square points shows the measured values of the second shape data.

  In the middle graph, since the optical axis is not shifted from the center O9 of the groove cross section Q2, the point groups g11 and g12 extend substantially in the horizontal direction. In the upper graph, since the optical axis is shifted to the right (FIG. 9) with respect to the groove cross section Q2, the point groups g11 and g12 extend obliquely upward to the right. In the lower graph, since the optical axis is shifted to the left (FIG. 9) with respect to the groove cross section Q2, the point groups g11 and g12 extend obliquely downward to the right.

  In any graph, the deviation between the point group 11 and the point group 12 is slight, and the corrected first obtained by reducing the distance d (w) corresponding to the position ZD by the method of the fourth embodiment. It can be seen that the one shape data is equivalent to the measured value of the second shape data at the position ZD.

  The flowchart according to the fourth embodiment may adopt the same flowchart as FIG. 8 described in the third embodiment. In this case, the processes (1) to (6) described in the fourth embodiment may be executed in S810 of FIG. 8, that is, the second shape data correction step. Specifically, when acquiring the second shape data at the position ZD, the second shape data acquisition unit 712 is obtained by moving the measurement object 300 in the Z direction in the range of −δ to + δ around the position ZD. The above processes (1) to (6) may be applied to each of the plurality of second measurement data.

  As described above, according to the evaluation apparatus according to the fourth embodiment, even if the optical axis of the sensor unit 130 is deviated from the center O9 of the groove section Q2, the processing accuracy of the groove 302 can be accurately evaluated.

(Embodiment 5)
The fifth embodiment is the same as the second embodiment in which the shape of the groove section Q2 in the entire region of the groove 302 is evaluated by moving the measurement object 300 in the Z direction while rotating around the central axis CZ. The method of Embodiment 3 or Embodiment 4 is applied.

  FIG. 14 is a flowchart showing processing of the evaluation apparatus according to Embodiment 5 of the present invention. In FIG. 14, the difference from FIG. 7 is in S1306. In S1306, each of the plurality of second shape data acquired in S1305 is corrected using the method described in the third embodiment or the fourth embodiment. Other than that, S1301 to S1304 are the same as S701 to S704 in FIG. 7, and S1307 to S1310 are the same as S706 to S709 in FIG. In S1304, the position ZD that is initially positioned may be the above-described position ZD0, and the position ZD that is subsequently positioned may be the above-described position ZD1.

  Thus, according to the evaluation apparatus according to Embodiment 5, the shape of the entire region of the groove 302 can be evaluated even when the optical axis of the sensor unit 130 is deviated from the center O9 of the groove cross section Q2. As a result, the groove processing accuracy can be more accurately evaluated. In the flowchart of FIG. 14, the measurement object 300 is rotated about the central axis CZ and moved to the Z axis intermittently, but may be continuously performed. In this case, the processes of S1307 and S1308 may be omitted. In S1305, the second shape data corresponding to the position ZD1 may be measured without moving the measurement object 300 in the Z direction within the range from −δ to + δ. In S1306, the second shape data may be corrected by applying the processes (1) to (6) described above to one second shape data.

  Further, in the fifth embodiment, the amount of change in depth with respect to the unit rotation angle of the measurement object 300 whose ratio D is around the central axis CZ may be defined. In this case, the change amount d with respect to the position ZD1 stored in the memory 714 is calculated by multiplying the rotation angle from the state where the position ZD0 is located directly below the position Z2 to the position ZD1 reaching the position Z2 by the ratio D. It only has to be done.

130 sensor units 131, 132, 133 sensor element 300 measurement object 320 end 400 reference measurement object 402 groove 700 control unit 710 movement control unit 711 first shape data acquisition unit 712 second shape data acquisition unit 713 evaluation unit 714 memory 902 Groove A, B Intersection CZ Center axis L11, L21 Extension direction L12 Center line L13, L23 Groove bottom line L91, L92, L93 Optical axis O9 Center P11, P21 Intersection Q1, Q2 Groove cross section R91, R92, R93 Area Th Threshold range U Ratio f1, f2 Approximate function f3 Linear function

Claims (10)

An evaluation device for evaluating the shape of the groove of the measurement object in which the groove is spirally extended,
A reference measurement object including a first groove having the same shape as a design value of a groove cross section perpendicular to the extending direction of the groove of the measurement object;
The first groove is configured to be movable between a first position for measuring the groove cross-sectional shape in a non-contact manner and a second position for measuring the groove cross-sectional shape of the measurement object in a non-contact manner. A sensor unit;
A moving unit for moving the measurement object in parallel with a central axis of the measurement object;
A first shape data acquisition unit that positions the sensor unit at the first position, causes the sensor unit to measure a shape of a groove cross section of the first groove, and acquires first shape data;
The sensor unit is positioned at the second position, and the shape of the groove section of the second groove, which is the groove of the measurement object moved by the moving unit in parallel with the central axis, is continuously or intermittently connected to the sensor unit. A second shape data acquisition unit that automatically measures and acquires one or more second shape data;
An evaluation apparatus comprising: an evaluation unit that evaluates a shape of the second groove based on a difference between the first shape data and the one or more second shape data. The moving part includes a pair of support parts for supporting both ends of the measurement object,
When the reference measurement object is viewed from above downward, the extending direction of the first groove is parallel to the extending direction of the second groove, and the center line passes through the center of the reference measurement object in the thickness direction. The evaluation apparatus according to claim 1, wherein a first intersection point with a groove bottom line passing through a bottom portion of the first groove is installed on one support portion so as to intersect the central axis.   The evaluation device according to claim 2, wherein the sensor unit measures a shape of a groove cross section orthogonal to the extending direction of the first groove at the first intersection. When the second shape data acquisition unit measures the shape of the groove cross section at one position of the second groove, the measurement object is parallel to the central axis within a predetermined range based on the first position. Among the plurality of second shape data acquired by the sensor unit while moving, the second shape data with the smallest error from the first shape data is specified,
The evaluation device according to claim 1, wherein the evaluation unit evaluates the shape of the groove cross section at the position 1 based on the difference between the specified second shape data and the first shape data. .   The evaluation apparatus according to claim 4, wherein the second shape data acquisition unit employs a least square error as the error. The second groove is a groove whose depth changes at a constant rate in the extending direction,
A memory for storing a change amount of the depth with respect to the first shape data of each of the one or more second shape data calculated based on the one or more positions of the second groove and the ratio; Prepared,
The second shape data acquisition unit corrects each of the one or more second shape data so that the amount of change is removed from the one or more second shape data,
The evaluation apparatus according to claim 1, wherein the evaluation unit evaluates a shape of the second groove based on a difference between the one or more second shape data after correction and the first shape data. The sensor unit includes a plurality of sensor elements that measure the shape of the groove cross section at one position of the second groove by dividing it into a plurality of regions,
At least one sensor element of the plurality of sensor elements is a first sensor element that measures a first region of the groove cross section in which an optical axis is shifted from a bottom of the groove cross section,
The second shape data acquisition unit
A first process for calculating a first approximation function indicating the shape of the first region from the first shape data measured by the first sensor element;
A second process of calculating a second approximate function by subtracting or adding the amount of change corresponding to the position of 1 of the second groove from the first approximate function;
The calculation of the distance between the first approximate function and the third intersection of the linear function indicating the optical axis and the fourth intersection of the second approximate function and the linear function is performed in parallel while maintaining the inclination of the linear function. A third process for calculating a plurality of distances by repeating the movement, and
The fourth process of correcting the second shape data by adding or subtracting the plurality of distances from the second shape data of the one position measured by the first sensor element. Evaluation device.   The second shape data acquisition unit divides the first region into one or a plurality of sections so that an error between the first approximation function and the design value is equal to or less than a threshold range in the first process, The evaluation apparatus according to claim 7, wherein one or a plurality of first approximation functions that approximate a shape of a section are calculated, and the second to fourth processes are executed for each of the sections. The moving unit moves the measurement object in parallel with the central axis while rotating the measurement object about the central axis,
The second shape data acquisition unit sets the shape of the groove cross section of the second groove of the measurement object that is moved in parallel with the central axis while being rotated about the central axis by the moving unit to the sensor unit. The evaluation apparatus according to claim 1, wherein a plurality of second shape data indicating a shape of a groove cross-section at a plurality of positions of the second groove is acquired by continuously or intermittently measuring. An evaluation method for evaluating the shape of a groove of a measurement object in which the groove is spirally extended,
First shape data obtained by causing the sensor section to measure the shape of the groove cross section of the reference measurement object including the first groove having the same shape as the design value of the groove cross section perpendicular to the extending direction of the groove of the measurement object without contact. Get
A plurality of second shape data is acquired by causing the sensor section to continuously or intermittently measure the shape of the cross section of the second groove of the measurement object moved in parallel with the central axis by the moving portion. ,
An evaluation method for evaluating a shape of the second groove based on a difference between the first shape data and the plurality of second shape data.

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