JP2017052037A - Measuring method of surface shape of grindstone working plane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring method which can measure accurately a convex part shape at a grindstone working plane that influences especially largely on the performance of a workpiece ground by a grindstone.SOLUTION: Provided is a measuring method of the surface shape of the working plane of a grindstone for polishing a workpiece. The method includes (1) a step in which light is emitted to various measuring positions on the working plane by using a non-contact laser displacement meter and measuring data is acquired including plural measuring values indicating displacement amounts, and (2) a step in which, regarding each segment included in the working plane, based on the valid measuring data excluding invalid data from measuring data corresponding to the segment, a displacement amount corresponding to the segment is decided. The invalid data include N (N is an integer equal to two or more) measuring values from the small side. However, the magnitude of the measuring value is defined so that the value corresponding to the more convex part side of the working plane becomes larger and the value corresponding to the more concave part side of the working plane becomes smaller.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method and an apparatus for measuring the surface shape of a work surface of a grindstone.

  The surface shape of the work surface of the grindstone greatly affects the performance of the workpiece polished on the work surface. Therefore, it is desired to accurately measure the surface shape of the work surface of the grindstone. Patent Document 1 discloses that a surface shape of a work surface of a grindstone is measured using a non-contact distance sensor.

JP-A-8-243905

  By the way, there are various types of grindstones, but any grindstone usually has fine irregularities on the surface. And it is the shape of the convex part which functions as a cutting edge that has a great influence on the performance of a workpiece polished with a grindstone. Therefore, it is important to accurately measure the shape of such a convex portion.

  However, when trying to measure the shape of the work surface using a non-contact laser displacement meter, the laser light is irregularly reflected by the recesses as shown in FIG. Therefore, the measurement value based on the reflected light at the concave portion becomes noise, and it is difficult to accurately evaluate the shape of the convex portion. FIG. 1 shows a cross section of a local region near the surface of the grindstone.

  An object of this invention is to provide the measuring method and apparatus which can measure correctly the shape of the convex part in the working surface of a grindstone which influences the performance of the workpiece | work grind | polished with a grindstone especially greatly.

A measuring method according to a first aspect of the present invention is a measuring method of a surface shape of a work surface of a grindstone for polishing a workpiece, and includes the following steps (1) and (2).
(1) A step of projecting light toward various measurement positions on the work surface using a non-contact laser displacement meter, and obtaining measurement data including a plurality of measurement values representing the amount of displacement.
(2) A step of determining, for each segment included in the work surface, the amount of displacement corresponding to the segment based on valid measurement data obtained by eliminating invalid measurement data from the measurement data corresponding to the segment.
The invalid measurement data includes N measurement values (N is an integer of 2 or more) from the smaller side. However, the magnitude of the measured value is defined to be larger as the value corresponding to the convex side of the work surface and smaller as the value corresponding to the concave side of the work surface.

  A measurement method according to a second aspect of the present invention is the measurement method according to the first aspect, wherein the invalid measurement data includes M measurement values (M is an integer of 2 or more) from the larger side. It is.

  The measuring method according to the third aspect of the present invention is the measuring method according to the second aspect, and N ≧ 10M.

  A measurement method according to a fourth aspect of the present invention is the measurement method according to any one of the first aspect to the third aspect, wherein the determining step is performed for each segment included in the work surface. The displacement corresponding to the segment is determined by averaging the measurement values included in the corresponding effective measurement data.

  A measuring apparatus according to a fifth aspect of the present invention is a measuring apparatus for the surface shape of a work surface of a grindstone for polishing a workpiece, and includes an acquisition unit and a determination unit. The acquisition unit acquires measurement data including a plurality of measurement values representing a displacement amount obtained as a result of projecting toward various measurement positions on the work surface using a non-contact laser displacement meter. The determination unit determines, for each segment included in the work surface, the displacement corresponding to the segment based on valid measurement data obtained by eliminating invalid measurement data from the measurement data corresponding to the segment. The invalid measurement data includes N measurement values (N is an integer of 2 or more) from the smaller side. However, the magnitude of the measured value is defined to be larger as the value corresponding to the convex side of the work surface and smaller as the value corresponding to the concave side of the work surface.

  According to the present invention, the surface shape of the work surface of the grindstone is measured by the non-contact laser displacement meter. At this time, the amount of displacement in each segment included on the work surface is not determined based on all measured values corresponding to the segment, but N pieces of measurement are measured from the smaller side when determining the amount of displacement. The value is ignored. In other words, the measurement value corresponding to the recess in the work surface is ignored. Therefore, it is possible to accurately measure the shape of the convex portion on the work surface of the grindstone, which has a great influence on the performance of the workpiece polished by the grindstone.

The figure which shows the mode of reflection of the laser beam projected on the work surface of the grindstone from the non-contact laser displacement meter. 1 is an overall configuration diagram of a measuring apparatus according to an embodiment of the present invention. The block block diagram of a laser displacement meter and an analysis apparatus. The flowchart which shows the flow of the measuring method which concerns on one Embodiment of this invention. The graph which plotted the measured value by one scan process. The graph showing the surface shape of the working surface of a grindstone. The flowchart which shows the flow of the manufacturing method of a grindstone. The figure which shows the mode of dressing of a grindstone. The figure which shows the mode of grinding | polishing with a grindstone. The graph showing the surface shape of the working surface of the grindstone concerning an example and comparative example 1. FIG. The graph showing the surface shape of the working surface of the grindstone concerning comparative example 2.

  Hereinafter, a method and apparatus for measuring the surface shape of a work surface of a grindstone according to an embodiment of the present invention will be described with reference to the drawings. Moreover, the manufacturing method of the grindstone using the same measuring method is also demonstrated.

<1. Measuring device>
In FIG. 2, the measuring apparatus 2 of the surface shape of the work surface 10 of the grindstone 1 which concerns on this embodiment is shown. The measuring device 2 includes a laser displacement meter 3 and an analysis device 4 that analyzes data measured by the laser displacement meter 3. The laser displacement meter 3 is a non-contact type distance sensor, which irradiates a laser beam toward the work surface 10 of the grindstone 1 and receives a reflected wave thereof, whereby a displacement amount corresponding to the distance to the work surface 10. Measure. Measurement data representing such a displacement amount is output from the laser displacement meter 3 to the analysis device 4 via a wired or wireless communication line.

  The grindstone 1 according to this embodiment is a porous grindstone. Moreover, the grindstone 1 is a grindstone for grinding, and has a generally cylindrical shape. And the side surface part of this substantially cylindrical-shaped grindstone 1 becomes the work surface 10 for grind | polishing a workpiece. The grindstone 1 is connected to a rotary shaft 15 that extends along the central axis A1 of the grindstone 1. The rotary shaft 15 is connected to a drive motor 16 and is rotated at a high speed by the drive motor 16. That is, the drive motor 16 can rotate the grindstone 1 around the central axis A1 at high speed. The rotating shaft 15 and the drive motor 16 according to the present embodiment can be a part of a workpiece polishing machine including the grindstone 1.

  The measuring device 2 further includes a moving mechanism 5 that linearly moves the laser displacement meter 3. The laser displacement meter 3 is moved by the moving mechanism 5 in parallel to the central axis A1 of the grindstone 1 with a certain distance from the grindstone 1. During the movement, the laser displacement meter 3 is fixed to the moving mechanism 5 so that the light emitting unit 31 and the light receiving unit 35 are always directed toward the work surface 10 of the grindstone 1. The light emitting unit 31 is a unit that emits laser light, and the light receiving unit 35 is a unit that receives the reflected light. As long as the moving mechanism 5 can linearly move the laser displacement meter 3 as described above, its specific configuration is not limited. For example, as shown in FIG. 2, a known linear movement mechanism including a guide rail 50, a ball screw 51, a motor 52, and the like can be used.

  FIG. 3 is a block configuration diagram of the laser displacement meter 3 and the analysis device 4. Although the laser displacement meter 3 can be configured in various ways, in the present embodiment, the light emitting unit 31 includes a semiconductor laser device 32 and a light projecting lens 33. The light projection lens 33 is disposed on the front surface of the semiconductor laser device 32 and spreads light from the semiconductor laser device 32 in a band shape. In addition, the light receiving unit 35 includes a light receiving element 36 such as a CMOS image sensor and a light receiving lens 37. The light receiving lens 37 is disposed in front of the light receiving element 36 and forms an image on the light receiving element 36 of the laser light diffusely reflected by the surface of the measurement object. The laser displacement meter 3 further includes a control unit 38 that controls the operations of the light emitting unit 31 and the light receiving unit 35. The control unit 38 includes a circuit board on which a CPU, a ROM, a RAM, and the like are mounted. The control unit 38 determines a measurement value representing the amount of displacement according to the imaging position on the light receiving element 36 and outputs the measurement value to the outside as measurement data. . Since the light emitted from the semiconductor laser device 32 has a certain width, a large number of measurement values are obtained for each irradiation. The laser displacement meter 3 is also equipped with a memory 39 for storing the measurement data.

  The analysis device 4 according to the present embodiment is simply a general-purpose personal computer as hardware, and an analysis program 6 is installed as shown in FIG. The analysis program 6 is software for specifying the shape of the work surface 10 of the grindstone 1 based on the measurement data output from the laser displacement meter 3, and causes the analysis device 4 to perform an operation described later. The analysis program 6 can be installed from a computer-readable recording medium 40 such as a CD-ROM or USB memory.

  The analysis device 4 includes a display unit 41, an input unit 42, a storage unit 43, a control unit 44, and a communication unit 45. These units 41 to 45 are connected via a bus line 46 and can communicate with each other. The display unit 41 can be configured with a liquid crystal display or the like, and displays information to be described later to the user. The input unit 42 can be configured with a mouse, a keyboard, a touch panel, and the like, and accepts an operation from the user for the analysis device 4. The storage unit 43 can be configured by a nonvolatile storage device such as a hard disk. In the storage unit 43, the analysis program 6 is stored, and the measurement data sent from the laser displacement meter 3 is stored. The communication unit 45 is a communication interface that enables communication between the analysis device 4 and an external device, and receives measurement data from the laser displacement meter 3.

  The control unit 44 can be configured by a CPU, a ROM, a RAM, and the like. The control unit 44 virtually operates as the acquisition unit 44A, the determination unit 44B, and the display control unit 44C by reading and executing the analysis program 6 in the storage unit 43. Details of the operations of the respective units 44A to 44C will be described later.

<2. Measuring method>
Then, the measuring method of the surface shape of the working surface 10 of the grindstone 1 implemented using the above-mentioned measuring apparatus 2 is demonstrated, referring FIG.

  First, as step S1, as shown in FIG. 2, the measuring device 2 is set in a polishing machine on which the grindstone 1 is set. Subsequently, the drive motor 16 included in the polishing machine is driven to rotate the rotating shaft 15 and the grindstone 1 around the central axis A1 at high speed. The rotation speed can be, for example, 1500 to 2000 rpm.

  Subsequently, as step S2, the laser displacement meter 3 is arranged in front of the end of the work surface 10 of the grindstone 1 in the direction of the central axis A1, and the moving mechanism 5 and the laser displacement meter 3 are driven in this state. Thereby, the laser displacement meter 3 measures displacement amounts at various measurement positions on the work surface 10 while being moved linearly from one end to the other end of the grindstone 1 along the guide rail 50 by the moving mechanism 5. To do. That is, in step S2, the light emitting unit 31 of the laser displacement meter 3 projects light toward various measurement positions arranged in parallel with the central axis A1 on the work surface 10, and the light receiving unit 35 receives the reflected light. And the control part 38 acquires the measured value showing the displacement amount in each measurement position.

  In the present embodiment, the various control parameters in step S2 are as follows. That is, in one light emission process by the light emitting unit 31, a laser beam is irradiated onto an 8 mm wide region (hereinafter referred to as a target region) along the direction of the central axis A 1 on the work surface 10. Then, the reflected light is processed by the light receiving unit 35 and the control unit 38, whereby 800 measured values are acquired. In addition, since the grindstone 1 rotates at high speed, the target area is actually a spiral area. Further, the control unit 38 extracts 50 measurement values corresponding to a region having a width of 0.5 mm in the central portion of the target region from among the 800 measurement values. Then, the maximum value of the 50 measured values is set as a measured value of the displacement amount by the light emission process at that time. In addition, the magnitude of the measured value representing the amount of displacement is larger as the value corresponding to the convex side of the work surface 10 (the side closer to the laser displacement meter 3), and is larger than the concave side of the work surface 10 (from the laser displacement meter 3). The value corresponding to the far side) is defined to be smaller.

  The laser displacement meter 3 moves in the direction of the central axis A1 at a speed of 160 mm / min. In other words, it takes 0.375 seconds to move 1 mm. On the other hand, the light emitting unit 31 performs the above light emission processing at a cycle of 1 kHz. For this reason, every time the laser displacement meter 3 moves 1 mm along the direction of the central axis A1, measurement values representing 375 displacement amounts are acquired. Therefore, step S2 can also be regarded as a step of repeatedly executing a process of obtaining 375 measurement values (hereinafter referred to as a scan process) every 1 mm section. However, one scan process includes 375 light emission processes. In this embodiment, the length of the grindstone 1 in the direction of the central axis A1 is 25 cm. In this case, the scanning process is repeated 250 times. The measurement data acquired here is stored in the memory 39.

  In subsequent step S <b> 3, the measurement data acquired in step S <b> 2 is transmitted from the laser displacement meter 3 to the analysis device 4 via the communication unit 45. In other words, the acquisition unit 44 </ b> A of the analysis device 4 receives the measurement data stored in the memory 39 from the laser displacement meter 3 and stores it in the storage unit 43.

  Next, the determination unit 44B of the analysis device 4 determines a displacement amount for each section (hereinafter referred to as a segment) set on the work surface 10 at intervals of 1 mm along the direction of the central axis A1.

  First, the determination unit 44B performs the following process on each segment in step S4. That is, invalid measurement data is excluded from measurement data including 375 measurement values corresponding to the currently processed segment, and valid measurement data is extracted. More specifically, among the 375 measurement values, the 11th to 20th measurement values in the descending order are set as effective measurement data. In other words, the invalid measurement data is 355 measurement values from the smaller side and 10 measurement values from the larger side among the 375 measurement values.

  Here, FIG. 5 is a graph of measured values representing 375 displacement amounts in a certain segment (1 mm section). Although the grindstone 1 has fine irregularities on the surface, it is the shape of the convex portions that particularly affects the performance of the grindstone 1 or the workpiece polished by the grindstone 1. Therefore, even if 375 measurement values are acquired in one scanning process, the data that should be noted among these 375 measurement values is data of a convex portion having a relatively large displacement amount ( (See FIG. 5). Therefore, in step S4, the lower 355 data corresponding to the recesses on the surface of the grindstone 1 are excluded as invalid measurement data.

  Further, among the 375 measurement values, even the higher order measurement values correspond to the foreign matter such as the sharpened abrasive grains adhering to the surface of the grindstone 1, and so on. It may not correspond to the convex part. Also, the measured value can be increased due to irregular reflection in the recess, noise caused by the laser displacement meter 3, or the like. Therefore, in order to avoid such a value, in step S4, 10 measurement values from the larger side among the 375 measurement values are excluded as invalid measurement data.

  In the present embodiment, as described above, 355 measurement values from the smaller side and 10 measurement values from the larger side are invalid measurement data. However, the number of measurement values on the small side and / or large side that should be used as invalid measurement data depends on conditions such as the type of grindstone that is the object to be measured and the type of laser displacement meter. Accordingly, it can be set as appropriate. Here, when N measurement values from the smaller side (N ≧ 2) and M measurement values from the larger side (M ≧ 2) are set as invalid measurement data, N ≧ 10M. Preferably, N ≧ 20M, more preferably N ≧ 30M. This is because the influence of the recess is usually larger than the error that increases the displacement.

  In subsequent step S5, the determination unit 44B determines a displacement amount corresponding to each segment based on the effective measurement data extracted in step S4. In the present embodiment, the determination unit 44B calculates an average value of ten measurement values included in the effective measurement data, and sets the average value as a displacement amount corresponding to the segment.

  Then, at the stage where steps S4 and S5 are completed, the distribution of the displacement along the direction of the central axis A1 of the work surface 10 of the grindstone 1, in other words, the surface shape of the work surface 10 of the grindstone 1 is determined. Therefore, as step S6, the display control unit 44C creates a screen showing the distribution of the displacement and displays it on the display unit 41. For example, the display control unit 44C creates a graph in which the displacement amount in each segment is plotted as shown in FIG. 6, and displays it. The measurement of the shape of the work surface 10 of the grindstone 1 is thus completed.

  According to the above measuring method, the shape of the convex portion corresponding to the cutting edge of the grindstone 1 can be correctly measured. As a result, management of the shape of the grindstone 1 becomes easy. It is also possible to compare the shape of the grindstone 1 with the shape of the workpiece polished by the grindstone 1 and grasp the correlation between the two. As a result, the shape of the workpiece can be stably formed.

<3. Manufacturing method of grinding wheel>
Hereinafter, the manufacturing method of the grindstone 1 using the above-mentioned measuring method is demonstrated, referring FIG. However, the measurement method described above is not limited to the example here, and can be used for any application that requires measurement of the surface shape of the work surface of the grindstone.

  First, dressing of the work surface 10 of the grindstone 1 is performed (step S21). In the present embodiment, as shown in FIG. 8, the shape of the side surface that becomes the work surface 10 of the grindstone 1 during high-speed rotation is corrected by the diamond dresser 7 having the diamond tip 70 disposed at the tip.

  In subsequent step S22, the surface shape of the work surface 10 of the grindstone 1 obtained in step S21 is specified by the measurement method described above. That is, the distribution of the displacement amount along the direction of the central axis A1 of the work surface 10 of the grindstone 1 is specified.

  In subsequent step S23, the workpiece is polished using the grindstone 1 obtained in step S21. In this embodiment, the workpiece is a roller 8 such as a developing roller or a transfer roller used in a printer. The roller 8 is made of rubber. FIG. 9 shows a state where the roller 8 is ground by the grindstone 1. In this example, the roller 8 has a cylindrical shape such that the radius is slightly larger toward the center along the direction of the central axis A1 and the radius is slightly smaller toward both ends. In this case, the grindstone 1 also has a cylindrical shape in which the radius is slightly smaller toward the center along the direction of the central axis A1 of the grindstone 1 and the radius is slightly larger toward both ends.

  In subsequent step S24, the surface shape of the polished surface of the workpiece after polishing in step S23 is measured. This measurement method can be arbitrarily selected. In addition, the workpiece here does not have a fine unevenness | corrugation on the surface like a grindstone, and has a comparatively flat outer surface shape. Therefore, in step S24, a device like the above-described measurement of the surface shape of the grindstone 1 is not required, and the surface shape can be accurately measured by various known measurement methods.

  In a succeeding step S25, whether or not the workpiece manufactured in step S23 is acceptable is determined based on the surface shape of the workpiece measured in step S24. Specifically, if the surface shape of the workpiece measured in step S24 is within the dimensional tolerance of the workpiece, it is accepted, and if it is not, it is rejected.

  If the workpiece is rejected in step S25, the work surface 10 of the grindstone 1 is dressed again (step S26). Also in the dressing here, the shape of the work surface 10 is corrected by the diamond dresser 7 while rotating the grindstone 1 at a high speed as in step S21. However, in step S26, the problem part of the grindstone 1 is taken into consideration while taking into account the part of the grindstone 1 corresponding to the part that has become a problem in the workpiece in the pass / fail judgment in step S25, the shape of the grindstone 1 measured in step S23, and the like. Tweak the. When the fine adjustment is completed, steps S22 to S25 are repeated again.

  On the other hand, when the workpiece is accepted in step S25, the grindstone 1 is also accepted, and the production of the grindstone 1 is completed. In this sense, it can be said that step S25 is a step of determining whether the grindstone 1 dressed in step S21 or step S26 is acceptable. Therefore, when the workpiece is accepted in step S25, the surface shape data of the work surface 10 of the grindstone 1 measured in the immediately preceding step S22 is recorded as “correct data”. Thereafter, the grindstone 1 can be maintained while referring to the “correct data”. For example, after manufacturing a large number of workpieces with the grindstone 1 after passing, the shape of the work surface 10 of the grindstone 1 is measured by the above-described measurement method, and this is compared with the “correct answer data” to determine the state of the grindstone 1. Inspection can be performed. For example, in the case of a grindstone for polishing rubber products, clogging may occur due to long-term use (for example, about one month), and cutting force may be reduced. In such a case, it is necessary to perform dressing again to eliminate clogging. At this time, “correct data” is used. That is, the surface shape of the grindstone that has been used for a long period of time can be measured by the above measuring method, and compared with this and the “correct data”, the surface shape of the grindstone can be redressed so as to approach the “correct data”.

<4. Modification>
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible unless it deviates from the meaning. For example, the following changes can be made. Moreover, the gist of the following modifications can be combined as appropriate.

<4-1>
In the above embodiment, an example in which the shape of the side surface of a substantially cylindrical grindstone rotating at a high speed is shown, but the same measurement method can be applied to various grindstones. For example, the present invention can be applied particularly effectively to a disk-shaped or belt-shaped object (abrasive material) that rotates (moves) at high speed.

<4-2>
In the above embodiment, the shape of the grindstone is automatically determined by the analysis program 6 based on the measurement data obtained by the laser displacement meter 3, but part or all of the above processing by the analysis program 6 may be performed manually. it can.

  Examples of the present invention will be described below. However, the present invention is not limited to the following examples.

  As a measurement object, a cylindrical grindstone having a diameter of 405 mm and a height of 50 mm was created. This grindstone was a porous grindstone. And while rotating this grindstone at the rotational speed of 1590 rpm, the surface shape of the working surface (side surface of a cylinder) of this grindstone was measured by the measuring method demonstrated in the said embodiment. Specifically, the scan process was repeated at 1 mm intervals along the direction of the central axis A1, and 375 displacement measurement values were acquired per scan process. The laser displacement meter used at this time was an ultra-high speed inline profile measuring instrument LJ-V7020 manufactured by Keyence Corporation. And the data of the distribution of the displacement amount of the work surface of the grindstone specified by this measurement were taken as examples.

  Further, as Comparative Example 1, the same measurement data as in the example was analyzed by a different method, and the distribution data of the displacement amount of the work surface of the grindstone was specified. Specifically, as described in the above embodiment, smoothing and median processing is performed in the A1 direction on the 800 points of data obtained in each light emission processing, and averaging and sampling in the time axis (sampling period) direction. Median processing was performed. Of the 800 measured values, 50 measured values corresponding to the 0.5 mm wide region at the center of the target region were extracted. A value obtained by multiplying the maximum value of the 50 measured values by the moving average was used as an output value corresponding to the light emission processing. And the value which averaged 375 output values corresponding to each segment was made into the measured value of the displacement amount in the said segment.

  Further, as Comparative Example 2, the same measurement data as in the example was analyzed by a different method, and the distribution data of the displacement amount of the work surface of the grindstone was specified. Specifically, the maximum value of 375 output values of each segment in Comparative Example 1 was defined as the displacement amount in the segment.

  FIG. 10 is a diagram showing data on the distribution of the amount of displacement of the working surface of the grindstone according to Example 1 and Comparative Example 1. FIG. 11 is a diagram showing data on the distribution of the amount of displacement of the work surface of the grindstone according to Comparative Example 2. From these figures, in the example, a smoother work surface shape is obtained than in the first and second comparative examples. Therefore, the example more accurately represents the distribution of the convex portions of the grindstone than Comparative Examples 1 and 2, and it was confirmed that the comparison with the shape of the polished surface of the workpiece was easier.

DESCRIPTION OF SYMBOLS 1 Grinding wheel 10 Work surface 2 Measuring device 3 Laser displacement meter 4 Analysis device

Claims (5)

A method for measuring a surface shape of a work surface of a grindstone for polishing a workpiece,
Projecting to various measurement positions on the work surface using a non-contact laser displacement meter, obtaining measurement data including a plurality of measurement values representing the amount of displacement;
Determining, for each segment included in the work surface, the amount of displacement corresponding to the segment based on valid measurement data obtained by eliminating invalid measurement data from the measurement data corresponding to the segment;
The invalid measurement data includes N measurement values (N is an integer of 2 or more) from the smaller side,
However, the magnitude of the measured value is defined as the value corresponding to the convex side of the work surface is larger and the value corresponding to the concave side of the work surface is smaller.
Measuring method. The invalid measurement data includes M measurement values (M is an integer of 2 or more) from the larger side.
The measurement method according to claim 1. N ≧ 10M.
The measurement method according to claim 2. The determining step determines, for each segment included in the work surface, the amount of displacement corresponding to the segment by averaging the measurement values included in the effective measurement data corresponding to the segment. ,
The measurement method according to claim 1. A device for measuring the surface shape of a work surface of a grindstone for polishing a workpiece,
An acquisition unit for acquiring measurement data including a plurality of measurement values representing a displacement amount obtained as a result of projecting toward various measurement positions on the work surface using a non-contact laser displacement meter;
For each segment included in the work surface, a determination unit that determines the amount of displacement corresponding to the segment based on effective measurement data obtained by eliminating invalid measurement data from the measurement data corresponding to the segment,
The invalid measurement data includes N measurement values (N is an integer of 2 or more) from the smaller side,
However, the magnitude of the measured value is defined as the value corresponding to the convex side of the work surface is larger and the value corresponding to the concave side of the work surface is smaller.
measuring device.