KR102065190B1 - Grinding device for hard and brittle plate and method for measuring and compensating machining accuracy - Google Patents

Abstract

Also in the grinding device of the polar coordinate system, a grinding device for automatically setting a correction value based on the measurement of the finished workpiece and the measurement result using a camera that detects a carry-in error of the workpiece is obtained.
From the detection point in the several places of the other side to a straight line which acquires the image of two places about one side and the other side of the opposite side of the workpiece which were processed with the camera, and connects the detection point in two images The length of the repaired line is calculated, and the machining error is calculated from the dimensional error, and the correction value for correcting the machining error is calculated and set in the controller of the apparatus, in contrast to the calculated dimension and the dimension to be inherent.

Description

GRINDING DEVICE FOR HARD AND BRITTLE PLATE AND METHOD FOR MEASURING AND COMPENSATING MACHINING ACCURACY}

This invention is based on the apparatus which grinds the edge of the glass substrate and other hard brittle plates used for the display panel of a portable terminal, the measuring method of the processing precision in such apparatus, and the measured value obtained by the said method. A method for correcting machining error.

In the grinding apparatus of a hard brittle plate, the apparatus which hold | maintains the apparatus of the biaxial direction (machining center system (orthogonal coordinate system) which carries out by moving in the X-Y direction) which runs the relative position of the grindstone with respect to a workpiece | straight line. There is a device of the contouring method (polar coordinate system) which performs processing by correlating and controlling the rotation angle of and the position of the grindstone moving in the radial direction of the rotation. The apparatus of the rectangular coordinate system is suitable for processing a large, rectangular hard brittle plate like a glass plate for a display panel of a television receiver. On the other hand, the device of the polar coordinate system is suitable for the processing of small hard brittle plates such as glass plates used for display panels of portable terminals, and has a large degree of freedom in processing shape and the device can be made smaller than the devices of the rectangular coordinate system. There is a characteristic to say.

The grinding apparatus of a hard brittle plate cannot position a workpiece | work on a table by the method of contacting the reference | standard side of a workpiece | work to the protrusion formed in the table, and positioning. Therefore, it is necessary to perform processing by setting the correction value in the controller to process the workpiece held on the table in the correct position at the position deviated from the correct position (deviation).

Therefore, whenever the camera is installed in the apparatus, and the workpiece is brought into the grinding apparatus and fixed on the table, the camera must photograph the corner or positioning mark of the workpiece on the table, and the corner or positioning mark must be present from the image. Deviation at the position to be detected is detected, and the correction value of the rotation angle and the grindstone position of the table is calculated from the detected deviation, and processing is performed while correcting the command value from the controller using the correction value.

On the other hand, the processing accuracy of a workpiece | work decreases by the aging change of a machine, heat deformation, abrasion of a grindstone, etc. In order to prevent such deterioration of machining accuracy over time, the workpieces are removed for every predetermined number of workpieces, the workpiece dimensions are measured, and a correction value for correcting the machining accuracy is calculated from the measured values and input to the controller. By doing so, desired processing precision is maintained.

That is, in the grinding apparatus of a hard brittle plate, the correction value (correction value of a machine precision) for correcting the fall of the processing precision resulting from the heat deformation of a machine or the abrasion of a grindstone, and the worktable on the table of every said workpiece Two types of correction values with a correction value (correction value of an import error) which correct | deviate a deviation are correct | amended and a command value of the rotation angle of a table and a grindstone position is processed.

Regarding the correction value of the carry-in error, the carry-out error is conventionally detected from the image of the camera installed in the machine, and the correction value is set automatically. For example, Patent Document 3 discloses a technique for mounting a camera on a feed table moving in the radial direction of a work table with respect to the grinding device of the polar coordinate system, and automatically detecting the loading error of the work on the table by the camera. It is shown.

On the other hand, regarding the correction of the mechanical precision, Patent Document 1, in the grinding apparatus of the Cartesian coordinate system, measures the position and the chamfer width of the circumferential edge of the finished workpiece by using a camera installed to detect the carry-in error, Means for automatically setting the correction value of precision are shown. In addition, Patent Document 2 uses such a camera to measure the processed shape of the finished workpiece, and measures and corrects the mechanical precision (in Patent Document 2, the attachment error of the table attached to the upper end of the rotating spindle). The technique is shown.

Patent Document 1: Japanese Unexamined Patent Publication No. 2009-125876 Patent Document 2: Japanese Unexamined Patent Publication No. 2012-121100 Patent document 3: Unexamined-Japanese-Patent No. 2013-35089

In the grinding apparatus of the Cartesian coordinate system shown in Patent Document 1, the grinding wheel moves in two directions orthogonal to the work (X direction and Y direction) and performs processing related to the dimensional accuracy of the direction, so that the grinding wheel is sent in the direction. By measuring the finished workpiece with a camera mounted on the conveyer, it is possible to relatively easily calculate the correction value of the mechanical precision. In particular, as shown in Patent Literature 1, in the structure in which two grindstones for simultaneously processing the opposite sides of the work are mounted, and the cameras are mounted on the transfer tables of the respective grindstones, the two opposite sides of the finished work are two cameras. It is possible to measure the workpiece dimensions (diameter dimension in the direction orthogonal to the side to be machined) by simultaneously photographing the workpiece, so that the workpiece is measured in a relatively short time, and the correction value of the mechanical precision is calculated based on the measured value. Automatic setting is also easy.

On the other hand, in the grinding device of the polar coordinate system, only one camera is provided, and since the operation direction of the workpiece and the grindstone does not coincide with the direction of measuring the machining accuracy, the measurement of the machining precision becomes quite complicated and cumbersome. . That is, as shown in Patent Literature 2, the machining accuracy of the workpiece is automatically and shortly used during continuous processing of the workpiece, for example, by acquiring multiple images using a workpiece provided with a special detection line. It was difficult to measure to.

Therefore, in the grinding device of the polar coordinate system, the correction value of the mechanical precision was set by the method of taking out the processed workpiece from the grinding device and measuring it manually, and inputting the correction value computed from the measured value manually. However, the setting of the correction value manually requires the time and skill required for the operation, the need for an expensive measuring instrument, and the risk of calculation or input errors occurring during calculation or input of the correction value. there is a problem.

This invention solves the problem mentioned above and also correct | amends a value based on the measurement of the workpiece | work which was processed using the camera provided in order to detect the carrying-in error of a workpiece, and the measurement result also in the grinding apparatus of a polar coordinate system. It is an object of the present invention to obtain a grinding device capable of efficiently performing the setting with less operation, and thereby automatically correcting the deterioration of the machining accuracy over time due to thermal deformation or grinding of the grindstone.

In the method of this invention, the measuring means 55 and the correction means 57 of a mechanical precision are called and executed at the predetermined timing during continuous processing of a workpiece | work, and after the said process is performed, the continuous processing of a workpiece | work is performed. Continue. The measuring means 55 of the mechanical precision measures the external dimension and the chamfer width of the finished work 1 using the camera 4 installed in the apparatus, and the correcting means 57 of the mechanical precision is The correction value of the machine precision is calculated based on the measured value, and the correction value of the machine precision with respect to the command value of each axis from the controller 5 is automatically set.

The measuring means 55 of the said mechanical precision has two images (P, Q) which are close to the both ends with respect to the one side 11 of the opposite side of the workpiece | work 1 which was processed, when one workpiece | work processing was complete | finished. Is obtained, and preferably images of a plurality of locations A, B, and C on the side with respect to the other side 12 on the opposite side, and the detection points (p, q and a, b, c in these images) are obtained. ) Coordinates (for example, coordinates with the table center as the origin).

Next, it acquires from the image of the location A, B, C of the said other side 12 to the straight line f which connects the detection points p and q acquired from the said image of two places P and Q. Lines g, h and i are drawn from each point of the detection points a, b and c, and intersections a ', b' and c 'where each line intersects the straight line and the points The dimensions La, Lb, and Lc between (a, b, and c) are calculated, and machining errors are obtained from these dimension errors in contrast with the calculated dimensions and the dimensions that should be inherent.

The correcting means 57 of the mechanical precision calculates a correction value for correcting the machining error calculated by the measuring means 55 of the mechanical precision and sets it to the controller 5 of the apparatus.

When acquiring images at each location, it is necessary to position the table and the grindstone feeder so that the optical axis of the camera is aligned with the acquisition position of the images. Can be detected. In the grinding device of the polar coordinate system, when a point where the distance from the table center becomes the same is selected, the camera can be moved to a plurality of points only by the table rotation. Therefore, it is preferable to make the said two places P and Q and two places B and C of both ends of the three places equidistant from a table center.

Moreover, in the grinding device of a polar coordinate system, when there exists an error in the radial position with respect to the table center of a grindstone, the error of the shape which a straight edge curves arises. In order to detect this error effectively, two places (B, where the distance from the table center is the same distance as that of the points P and Q) are obtained in plural places for acquiring an image for the other side 12 of the opposite side. It is good to set it as three places of one place (A) in the center of C) and both.

When the chamfering process is performed at the circumferential edge of the work, the chamfer width d of the location can be measured from the acquired images of each location, and the correction value for the chamfer width can be calculated and set. The measurement of the chamfer width d is an image of the ridge line 17 between the image 41 of the outer circumferential line or the chamfered surface 16 and the surface 15 of the hard brittle plate among the obtained images ( 47) the coordinates of two points (s, t) of predetermined intervals on the image and one point (u) on the image 47 or 41 of the other line of the image are obtained, and then the two points (s, t). Draw a waterline j from the point u on a straight line (which coincides with the image 41 of the outer circumferential edge in the drawing), and the intersection of the waterline crosses the straight line u Calculate the dimension (d) between one point (u), calculate the machining error from those dimensional errors in contrast to the calculated dimensions and the chamfer width that should be inherently, and calculate the correction value to correct this machining error. To the controller 5 of the controller.

The grinding apparatus of the hard brittle plate of this invention which implements said method is the camera 4 which can photograph the periphery of the workpiece | work 1 on the table 2, and several imaging points P, Q, A, B , C) coordinate acquisition means 52 for acquiring the coordinates of the predetermined detection point (p, q, a, b, c) on the image captured by the camera 4, and the shooting position setter 51 for setting C). ), A timing setter 53 for setting the measurement timing of mechanical precision, a dimension setter 54 for setting a plurality of work dimensions, and two places (P, Q set in the shooting position setter 51). ) And the coordinates of the respective detection points (p, q, a, b, c) from the camera 4 image of the other locations (A, B, C) and the two detection points (p, q) The machine precision of calculating the difference from the corresponding dimension set in the dimension setter 54 by calculating the lengths La, Lb, Lc of the waterline lowered from the detection points a, b, c at different points on the straight line to be connected. Measuring means (55) And a.

The grinding apparatus of the hard brittle plate of this invention which is preferable is the said coordinate acquisition means 52 which can acquire the coordinates of three predetermined detection points (s, t, u) on one image image | photographed with the camera 4 further. The measuring means 55 of the mechanical precision is provided from the other detection point u to a straight line connecting two detection points s and t of the three detection points acquired by the coordinate acquiring means 52. The length d of the dropped repair is obtained, and the difference between the length of the repaired repair and the corresponding dimension set in the dimension setter 54 is calculated.

Moreover, the grinding apparatus of the hard brittle plate of this invention is preferable using the calculation formula thru | or the calculation table 56 previously registered in the controller 5 from the difference of the dimension computed by the measuring means 55 of mechanical precision, Compensation means 57 of machine precision for calculating the correction value for the command value of each axis (theta), x of operation | movement, and setting it to the controller 5 is provided.

According to this invention, since the external dimension and the chamfer width of the finished workpiece processed by the grinding device of a hard brittle plate are automatically measured and corrected, the method by which an operator measures using a measuring instrument, and as described in patent document 2 Compared with the same method, the measurement time can be shortened, and the correction value for the error of the external dimension or the correction value for the chamfer width can be set automatically, and the time required for the measurement is short. The correction value can be set (updated) and high precision continuous processing can be realized.

In addition, since the correction value is automatically calculated and set, it is possible to avoid measurement errors and input errors caused by manual operation.

Further, according to the present invention, in the polar coordinate grinding device, in which conventional automatic measurement of the machining error is difficult, measurement and correction of the machining accuracy can be efficiently performed in a short time, and the machining error easily occurs in the grinding device of the polar coordinate system. Since it can be effectively measured and corrected, there is an effect that a space-saving grinding device can be obtained that maintains high processing accuracy and realizes continuous processing.

1: is explanatory drawing which shows the measurement location of the shape error of the processed workpiece | work in this invention.
2 is a diagram illustrating an example of detecting a detection point from an image of a circumferential edge of the chamfered workpiece.
3 is a side view illustrating the chamfered shape of the hard brittle plate.
4 is a diagram showing an exaggerated work shape error in the grinding device of the polar coordinate system.
Fig. 5 is a side view showing an embodiment of the grinding device of the polar coordinate system.
6 is a plan view showing the positional relationship between the workpiece, the grindstone, and the camera of the polar coordinate grinding device.
7 is a plan view showing the positional relationship between a workpiece, a grindstone, and a camera of a rectangular coordinate system grinding device.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described using a grinding | polishing apparatus of a contouring system as an example. 5 is a view showing an example of this type of grinding device. In the drawing, the work shaft 28 is a hollow rotary shaft in the vertical direction, and a table 2 is provided at the upper end, and the workpiece (glass plate) 1 to be processed is placed in a horizontal posture on the upper surface of the table 2. maintain. A negative pressure is supplied to the upper surface of the table 2 through the hollow hole of the work shaft 28, and the lower surface of the workpiece 1 is vacuum-adsorbed and fixed to the table 2. A main shaft motor (servo motor) 29 is connected to the lower end of the work shaft 28, and the main shaft motor 29 is connected to the controller 5 via a servo amplifier, and to the command of the controller 5. By this, the rotation angle θ of the work shaft 28 is controlled.

On the upper side of the work shaft 28, a horizontal feeder 21 is provided. The horizontal feeder 21 is movably guided by a horizontal guide in a horizontal direction (not shown), and is screwed into a horizontal feed screw 24 which is rotationally driven by the horizontal feed motor (servo motor) 23. have. The horizontal feed motor 23 is connected to the controller 5, and the movement position x of the horizontal feed stand 21 is controlled by the controller 5.

The vertical conveyer 25 is provided in the horizontal conveyer 21. The vertical feeder 25 is movably mounted to the vertical guide fixed to the horizontal feeder 21 and is screwed to the vertical feed screw 27 which is rotationally driven by the vertical feed motor 26. Are combined.

The grindstone shaft 31 of the vertical direction is axially supported by the vertical feeder 25, and the grindstone 3 is attached to the lower end of this grindstone shaft. The upper end of the grindstone shaft 31 is connected to the grindstone drive motor 34 with the toothed belt 33 interposed therebetween.

The shaft center O of the work shaft 28 and the shaft center of the grindstone shaft 31 are located on the same vertical surface n parallel to the moving direction of the transverse feed table 21. As shown in FIG. 6, in the contouring method, the controller 5 determines the amount of movement of the horizontal feeder 21 (= amount of movement of the grindstone 3) x and the rotation angle θ of the work shaft 28. By controlling in association, the peripheral edge processing of a desired planar shape is performed.

The camera 4 for acquiring the image of the workpiece conveyed on the table 2 is provided in the fixed position of the horizontal conveyance stand 21. As shown in FIG. 6, this camera 4 is provided at a position where the optical axis passes through the vertical plane n.

In the grinding device of the polar coordinate system, the controller 5 uses the rotation angle θ around the center O of the table 2 and the position of the grindstone 3 in the radial direction of the table passing through the table center O. By controlling x) in association, the peripheral edge of the work 1 is processed. The controller 5 includes a photographing location setter 51, coordinate acquisition means 52, a timing setter 53, a dimension setter 54, a measuring means 55 of mechanical precision, and correction. Arithmetic expressions to calculation tables 56 for calculating the values, and correction means 57 for machine precision are provided. In the photographing location setter 51, two places P and Q on one side of the circumferential edge of the work 1 and three places A, B and C on the other side are set. The timing setter 53 sets a timing for measuring the mechanical accuracy, for example, the elapsed operating time and the number of workpieces. In the dimension setter 54, the regular dimension of the location corresponding to the workpiece dimension in which the measuring means 55 of precision is measured is registered.

When the timing set by the timing setter 53 is reached during continuous processing, if the workpiece is being processed, the workpiece is processed, and then, in the corresponding direction by the rotation of the table 2 and the movement of the grindstone 3 in the radial direction. Images (P, Q and A) including five points (p, q and a, b, c) of the outer periphery of the workpiece 1 processed with the camera 4 mounted on a transfer table for moving the grindstone 3 , B, C) are photographed, and the coordinates (for example, coordinates in a rectangular coordinate system in which the longitudinal direction and the width direction of the workpiece are the XY direction with the work center as the origin) are obtained from the image. The points p, q and b, c are points that are equidistant from the table center O on the two opposite sides 11 and 12 of the work 1, and the point a is the point b, c) is the center point (a).

As a method of obtaining the coordinates of these points from the image photographed with the camera 4, for example, as shown in Fig. 2, the respective points described above when the work 1 is processed into an accurate product shape, The table 2 and the camera 4 are moved so that the image center e is located, and an image of the work is obtained, and the line drawn from the image center e is projected to the image 41 of the outer peripheral edge projected on the image. Let the intersection of e be the point (p, q, a, b, c) of the measurement target, and the coordinate of the point (coordinate of the camera optical axis plus the deviation of the intersection from the optical axis) It is good to do.

In this way, the coordinates of the points p and q and the points a, b and c are obtained, and the straight line f passing through the points p and q is calculated by the equation registered in the controller 5 (Fig. 4). ) And the intersection (a 수, b ＇, c) of the water line (g, h, i) dropped on the straight line f from each point (a, b, c) on the other side and the straight line f. The coordinates of i) are obtained, and the intervals La, Lb, Lc of the points a, b, c of the opposite sides and these intersections a ', b', c 'are calculated. And the difference between these space | intervals and the dimension which should exist originally is made into the error of the processing shape of an outer peripheral edge. From this error, using a calculation formula or calculation table 56 registered in advance in the controller 5, a correction value for correcting the error is calculated, and set in the controller 5 as a correction value of machine precision.

As described in Patent Literature 2, in the grinding apparatus of the polar coordinate system, if there is an error in the mechanical precision and the carrying-in accuracy of the workpiece, the workpiece becomes an obliquely crushed fan shape as shown in FIG. 4. In Fig. 4, the shapes of the edges 11 and 12, which are circular arcs having a large curvature, are mainly influenced by the angle of rotation of the table due to the angle of the sides 13 and 14, which are obliquely affected by the positional error of the grindstone. Receive. The error due to thermal deformation of the machine or the wear of the grindstone affects the grindstone position relative to the center of the table and does not affect the rotation angle of the table so much. By setting a correction value, the fall of the machining precision by the time-dependent cause can be correct | amended substantially.

On the other hand, the processed workpiece is a workpiece automatically brought in, and an import error on the table exists. Therefore, it is needless to say that the positioning of the work and the calculation of the coordinates at the time of acquiring the image are corrected by positioning of the workpiece and corrected.

When the circumferential edge processing (machining to obtain the dimensional accuracy of the circumferential edge) and the chamfering of the work are performed, each image acquired to measure the processing precision is shown in FIG. 2 as shown in FIG. The image 47 of the ridgeline 17 generated between the chamfered surface 16 and the hard brittle plate surface 15 is projected. Therefore, two points (s, t) are taken at predetermined intervals in the image 41 of the outer periphery line of one of the two lines in this image, and the points u taken on the image 47 of the straight line and the ridge line connecting the two lines ), The intersection point u 'of the waterline j lowered in the straight line can be obtained, and the distance d between the point u and the intersection point u' can be obtained as the measured value of the chamfer width. By comparing the measured value of the width with the value of the chamfer width which is requested | required, the measurement precision of the chamfer width can be measured simultaneously with the measurement of the machining precision of a perimeter edge shape. On the other hand, the example of FIG. 2 shows the point u at the intersection of the waterline j lowered from the image center e to the straight line (the straight line coinciding with the image 41 of the outer line) and the image 47 of the ridgeline. Is taken, and point (u ') and point (e') mentioned above become the same point.

On the other hand, when the sides 11 and 12 are straight sides, a correction value is calculated from the difference (ΔLa, ΔLb, ΔLc) between the diameter dimensions La, Lb, Lc measured as described above and the dimensions that should be inherent. The calculation formula can be obtained geometrically and registered in the controller 5, but in the case where the sides 11 and 12 are curved edges such as circular arcs, the relationship between the above-described dimensional difference, the diameter of the whetstone and the positional precision is tested in advance by a test process. The correction value can be obtained by registering the relationship with the measured dimensions La, Lb, and Lc in the controller 5 as a calculation table.

1.work finished
4. Camera
11. Opposite side
12. Opposite side
15. Surface of hard brittle plate
16. Chamfer
17. Ridge
41. Image of outer ship
47. Burns
A, B, C, P, Q. Burns
a, b, c, p, q. Detection point
a ', b', c '. meet
d. Chamfer width
g, h, i, j. repair
La, Lb, Lc. Measurement dimensions

Claims (10)

As a measuring method of the processing precision in the grinding apparatus of the hard brittle plate provided with the camera which can photograph the edge of the workpiece | work on a table in a machine,
The camera acquires two images on one side of the opposite side of the finished workpiece held on the table by the camera, acquires a plurality of images on the other side of the opposite side, and acquires coordinates of the detection points in each image. And an intersection intersecting the straight line and the straight line, which fall from each point of the detection point acquired from the plurality of images, and an intersection crossing the straight line, on a straight line connecting the detection points acquired from the two images, and between the respective points and the respective intersections. The measuring method of the processing precision in the grinding apparatus of a hard brittle plate which calculates the dimension of and measures the dimension difference between the calculated dimension and the dimension which should exist originally. The method of claim 1,
Two places on one side of the opposite side and a plurality of places on the other side are four places equidistant from the center of the table and one place in the center of two places equidistant above the other side. The measuring method of the processing precision characterized by the above-mentioned. The method according to claim 1 or 2,
Two points of predetermined intervals on the image of the outer circumference line or the image of the ridgeline formed between the surface of the hard brittle plate and the image of the other line of the image among the images at each location. The coordinates of one point of the phase are acquired, and the dimension between the perpendicular | vertical line (u ＇) of the said straight line and the said intersection of the said straight line and the said one point is calculated on the straight line which connects the said two points, and the calculated dimension is original A method for measuring machining accuracy, comprising calculating a dimensional difference from a chamfer width that should be present. The machining precision is measured by the method according to claim 1 or 2 at a predetermined timing during continuous machining of the workpiece, and the machining operation is performed using arithmetic formulas or calculation tables previously registered in the controller based on the measured values. A method for correcting the machining accuracy in a grinding apparatus of a hard brittle plate, in which a correction value for a command value of each axis in the controller is calculated and set. During the continuous machining of the workpiece, the machining precision is measured by the controller according to the method described in claim 3 at a predetermined timing, and based on the measured value, the command of each axis of the machining operation is calculated by using the calculation formula or calculation table registered in advance in the controller. The correction method of the processing precision in the grinding apparatus of a hard brittle plate which calculates and sets the correction value with respect to the said controller. Hard brittle plate provided with the camera which can photograph the periphery of the workpiece | work on a table, the photography location setter which sets a several shooting location, and the coordinate acquisition means which detects the coordinate of the predetermined detection point on the image image | photographed with this camera. In the grinding device of
With the timing setter and the dimension setter which sets the workpiece dimension of several places,
Equipped with measuring means of machine precision,
The measuring means of the mechanical precision acquires the coordinates of the respective detection points from the images of the cameras at two locations different from the two locations set at the shooting location setter at the timing set in the timing setter, and connects the two detection points. The grinding | polishing apparatus of the hard brittle plate which calculates the difference of the length of the repaired line which calculated | required from the detection point of the said other place in a straight line, and the difference between the calculated length and the corresponding dimension set to the said dimension setter. The method of claim 6,
The two places different from the two places set in the photographing point setter are four places equidistant from the center of the table on one side and the other side of the opposite side of the workpiece to be machined, and two at the same distance on the other side. It is one place in the center part of a point, The grinding apparatus of the hard brittle plate characterized by the above-mentioned. The method according to claim 6 or 7,
The coordinate acquisition means which can detect the coordinates of three predetermined detection points on the image image | photographed with the said camera, The said measuring means of the mechanical precision is the image of the said camera of the location set to the imaging | positioning position setter in the said timing. The coordinates of the three detection points are obtained from the graph, and the length of the waterline drawn from the other detection points is obtained on a straight line connecting two of the detection points, and the calculated length of the waterline and the corresponding dimension set in the dimension setter are obtained. Grinding device for hard brittle plates to calculate the difference. The method according to claim 6 or 7,
A hard brittle plate comprising mechanical correction means for calculating a correction value for a command value of each axis of a machining operation and setting it in the controller by using a calculation formula or calculation table previously registered in the controller from the difference in the dimensions. Grinding device. The method of claim 8,
A hard brittle plate comprising a correction means for calculating the correction value for the command value of each axis of the machining operation and setting it in the controller using a calculation formula or calculation table registered in advance in the controller from the difference in dimensions. Grinding device.

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