JP7654328B2 - Graduated plate and grinding device - Google Patents

Description

The present invention relates to a grinding device that holds and grinds a workpiece on the holding surface of a chuck table, a scale plate that is used to position a height measuring device at a predetermined position to measure the height of various points on the holding surface, and a grinding device equipped with scales.

Device chips equipped with devices such as ICs (Integrated circuits) and LSIs (Large Scale Integration) are manufactured from disk-shaped wafers. Multiple devices are provided on the front surface of a wafer, and the wafer is ground from the back surface to thin it, and then divided into individual devices to obtain individual device chips. Grinding of workpieces such as wafers is performed by a grinding device (see Patent Document 1). The grinding device has a chuck table that holds the workpiece, and a grinding unit that grinds the workpiece held by the chuck table.

The grinding unit includes a wheel mount on the underside of which a grinding wheel can be fixed, a spindle whose lower end is fixed to the center of the upper surface of the wheel mount, and a spindle housing that rotatably houses the upper end of the spindle. Inside the spindle housing, a rotational drive source such as a motor that rotates the spindle is provided.

The grinding wheel fixed to the wheel mount includes an annular wheel base that contacts the underside of the wheel mount, and grinding wheels arranged in a ring shape that are fixed to the underside of the wheel base. Rotating the spindle rotates the grinding wheel, and the grinding wheels rotate on a rotational path that is roughly parallel to the holding surface of the chuck table. Furthermore, the grinding device can rotate the chuck table around the table rotation axis that passes through the center of the holding surface. When the grinding wheel and chuck table are rotated and the grinding wheels are brought into contact with the workpiece, the workpiece is ground.

Here, the holding surface of the chuck table is a very gently inclined conical surface. In the grinding device, the inclination of the table rotation axis and spindle is determined so that the generatrix that constitutes the holding surface, which is closest to the rotation plane including the rotation orbit of the grinding wheel, is parallel to the rotation plane. By adjusting the relative inclination of the table rotation axis and spindle in this way, the workpiece can be ground so that the entire area of the workpiece has a uniform thickness.

When adjusting the inclination of the table rotation axis, etc., a height measuring device capable of measuring the height of each point on the holding surface is used. The height measuring device is attached to the wheel mount via a jig. The height measuring device is positioned sequentially over each measurement point on the holding surface, and measures the height of the holding surface at each measurement point (see Patent Document 2). For example, the operator adjusting the grinding device manually rotates the wheel mount around the spindle and moves the height measuring device to the specified measurement point.

JP 2009-141176 A JP 2013-141725 A

Like the grinding stone of a grinding wheel attached to a wheel mount, the height measuring device moves on a rotational orbit centered on the spindle when the wheel mount is rotated. This orbit overlaps with the center of the holding surface of the chuck table. When adjusting the inclination of the table rotation axis, etc., the height of the holding surface is measured at the two ends of the arc-shaped area of the holding surface that overlaps with this orbit, the center of the holding surface, and the midpoint between the ends and the center, etc.

Conventionally, workers would look into the space between the grinding unit and the chuck table from the side to confirm that the height measuring device was positioned at a specified measurement point. However, it is not easy to precisely sense the position of the height measuring device in the depth direction as seen by the worker. Also, when working above the grinding unit, the worker had to move to the side of the chuck table to check the position of the height measuring device every time the position of the height measuring device was changed. As a result, aligning the height measuring device was a factor that reduced work efficiency.

The present invention was made in consideration of these problems, and its purpose is to provide a scale plate and grinding device that can easily achieve high-precision alignment of a height measuring device fixed to a wheel mount.

According to one aspect of the present invention, there is provided a grinding device comprising: a chuck table having a holding surface on an upper surface thereof and suction-holding a disk-shaped workpiece on the holding surface; a rotatable spindle that can be raised and lowered by a grinding feed unit; and a wheel mount that is connected to a lower end of the spindle and can detachably support a grinding wheel having grinding stones arranged in an annular shape on its bottom surface, and a grinding unit that grinds the workpiece held on the chuck table, wherein the grinding wheel attached to the wheel mount is rotated, the grinding unit is lowered, and the grinding stone is brought into contact with the workpiece held on the holding surface of the chuck table, thereby grinding the workpiece. The wheel mount includes a chuck table that is attached to the wheel mount. a height gauge mounting mechanism capable of mounting a height gauge that measures the height position of the holding surface, a scale is provided on one of the upper or side surface of the wheel mount and an outer surface of the grinding unit other than the wheel mount and the spindle, which does not move even when the spindle of the grinding unit is rotated , and a mark indicating a point on the scale is provided on the other, the height gauge attached to the wheel mount by the height gauge mounting mechanism can be moved along the rotational orbit of the grinding wheel on the holding surface of the chuck table to measure height positions at various points on the holding surface with the height gauge, and the position of the height gauge on the holding surface along the rotational orbit can be detected by reading the point on the scale indicated by the mark.

Preferably, the scale is printed on a plate attached to one of the top or side surface of the wheel mount and an outer surface of the grinding unit other than the wheel mount and the spindle that does not move when the spindle is rotated .

Furthermore, preferably, the wheel mount is formed with a grinding wheel fixing hole through which a wheel fixing device for fixing the grinding wheel to the wheel mount is passed, and one of the plate and the mark can be fixed by a fixing device passed through the grinding wheel fixing hole.

Alternatively, preferably, the scale is printed on one of the top or side surface of the wheel mount and an outer surface of the grinding unit other than the wheel mount and the spindle that does not move when the spindle is rotated .

Also, preferably, the scale includes a first scale line, a second scale line, and a third scale line, and when the spindle is rotated 60°, the relative positional relationship between the second scale line and the mark coincides with the relative positional relationship between the first scale line and the mark before the rotation, and when the spindle is rotated 120°, the relative positional relationship between the third scale line and the mark coincides with the relative positional relationship between the first scale line and the mark before the rotation.

Moreover, preferably, the scale further includes a fourth scale line and a fifth scale line, and when the spindle is rotated 30°, the relative positional relationship between the fourth scale line and the mark coincides with the relative positional relationship between the first scale line and the mark before the rotation, and when the spindle is rotated 90°, the relative positional relationship between the fifth scale line and the mark coincides with the relative positional relationship between the first scale line and the mark before the rotation.

According to another aspect of the present invention, a grinding device is provided that includes a chuck table having a holding surface on its upper surface and suction-holding a disk-shaped workpiece on the holding surface, a rotatable spindle that can be raised and lowered by a grinding feed unit, a wheel mount that is connected to the lower end of the spindle and can detachably support a grinding wheel having grinding wheels arranged in a ring on its bottom surface, and a grinding unit that grinds the workpiece held on the chuck table, and that can grind the workpiece by rotating the grinding wheel attached to the wheel mount, lowering the grinding unit, and bringing the grinding wheels into contact with the workpiece held on the holding surface of the chuck table, the grinding device being provided with a top or side surface of the wheel mount and an outer surface of the grinding unit other than the wheel mount and the spindle. A scaled plate is provided that can be attached to the grinding device in combination with a marking provided on the other of the upper or side surface of the wheel mount and the outer surface of the grinding unit other than the wheel mount and the spindle, the scale being printed thereon and including a first scale line, a second scale line, and a third scale line, and is attachable to the grinding device such that when the spindle is rotated 60°, the relative positional relationship between the second scale line and the marking coincides with the relative positional relationship between the first scale line and the marking before the rotation, and when the spindle is rotated 120°, the relative positional relationship between the third scale line and the marking coincides with the relative positional relationship between the first scale line and the marking before the rotation.

Preferably, the scale further includes a fourth scale line and a fifth scale line, and is attachable to the grinding device such that when the spindle is rotated 30°, the relative positional relationship between the fourth scale line and the mark coincides with the relative positional relationship between the first scale line and the mark before the rotation, and when the spindle is rotated 90°, the relative positional relationship between the fifth scale line and the mark coincides with the relative positional relationship between the first scale line and the mark before the rotation.

Also, preferably, the wheel mount of the grinding device is formed with a grinding wheel fixing hole through which a wheel fixing device for fixing the grinding wheel to the wheel mount is passed, and the grinding wheel can be fixed to the grinding device by a fixing device passed through the grinding wheel fixing hole.

Or, preferably, it can be secured to the grinding device by tape or a magnet.

The grinding device and scaled plate according to one embodiment of the present invention are provided with a scale. This scale is used together with a mark provided on the grinding device. For example, when an operator adjusting the grinding device rotates the spindle to rotate the wheel mount, the relative positional relationship between the scale and the mark changes according to the rotational angle of the spindle. Therefore, the rotational angle of the spindle can be detected by checking the change in this positional relationship when the spindle is rotated.

The height measuring device, which is attached to the wheel mount with or without a jig, moves along the rotational path of the grinding stone of the grinding wheel when the spindle is rotated. Since the position of the height measuring device after the movement is determined by the rotation angle of the spindle, the position of the height measuring device can be identified if the rotation angle of the spindle can be detected. In other words, the position of the height measuring device on the holding surface can be detected by reading the point on the scale where the mark is pointing.

As a result, the person adjusting the grinding device can easily ascertain the position of the height measuring device by checking the scale and markings, without having to look between the grinding unit and the chuck table and directly see the height measuring device. In this case, there is no need to sense the position of the height measuring device in the depth direction as seen by the adjustment worker, and the position of the height measuring device can be identified more accurately. This also improves the accuracy of aligning the height measuring device.

Therefore, the present invention provides a scale plate and grinding device that can easily achieve high-precision alignment of a height measuring device fixed to a wheel mount.

FIG. 2 is a perspective view showing a grinding device. FIG. 2 is a perspective view showing a workpiece to be ground by the grinding device; 1 is a cross-sectional view that illustrates a grinding device that grinds a workpiece. FIG. 4 is a perspective view showing a grinding wheel being attached to a wheel mount. 2 is a plan view showing a schematic diagram of the rotational trajectory of a grinding wheel and the contact area of the grinding wheel on the back surface of a workpiece. FIG. 13 is a side view showing a schematic view of a state in which a height measuring device is attached to a grinding unit via a jig. FIG. 11 is a side view showing a schematic view of a state in which the height of each point on the holding surface of the chuck table is measured by a height measuring device attached to the grinding unit. FIG. FIG. 2 is a plan view illustrating a chuck table, a jig, and a height measuring device. Figure 9(A) is a perspective view showing typically how a scale plate is attached to a wheel mount, Figure 9(B) is a perspective view showing typically the wheel mount with the scale plate attached, and Figure 9(C) is a perspective view showing typically the wheel mount with scales printed on it. FIG. 2 is a plan view showing a schematic diagram of a scale plate.

An embodiment of the present invention will be described with reference to the drawings. The grinding device to which the scale plate according to this embodiment is attached grinds and thins the workpiece. First, the workpiece will be described. Figure 2 includes a perspective view that shows a schematic diagram of the workpiece 1.

The workpiece 1 is, for example, a substantially disk-shaped wafer made of a material such as Si, SiC (silicon carbide), GaN (gallium nitride), GaAs (gallium arsenide), or other semiconductor material. However, the workpiece 1 is not limited to this.

When multiple devices are arranged in a matrix on the front surface 1a of the workpiece 1, such as a disk-shaped wafer, and the workpiece 1 is divided into individual devices, individual device chips are obtained. If the workpiece 1 is first ground from the back surface 1b side using a grinding device to thin it, thin device chips are ultimately obtained. A tape-like protective member 3 (see Figure 3) is attached to the front surface 1a of the workpiece 1 that is ground by the grinding device to protect the devices and the like formed on the front surface 1a.

Next, the grinding device will be described in detail. FIG. 1 is a perspective view showing an example of the grinding device 2, and FIG. 3 is a cross-sectional view showing a part of the grinding device 2. The grinding device 2 includes a base 4 that supports each component. A recess 4a is formed on the top surface of the base 4 along the Y-axis direction.

In the recess 4a, there are provided a moving table 6 that can move along the Y-axis direction by a ball screw type moving mechanism, a chuck table 8 supported by the moving table 6, and a dustproof and drip-proof cover 4b that covers the opening of the recess 4a while exposing the chuck table 8. However, in FIG. 3, the dustproof and drip-proof cover 4b and the like are omitted. When the moving table 6 is moved along the Y-axis direction, the chuck table 8 moves along the Y-axis direction.

The chuck table 8 can hold the workpiece 1 to be ground by suction. The chuck table 8 has a frame 8a made of stainless steel or ceramics. A suction passage (not shown) is provided within the frame 8a, and one end of this suction passage is connected to a suction source (not shown) such as an ejector. The frame 8a has a recess on the upper surface thereof, which is a disk-shaped space. A roughly disk-shaped porous member 8b is housed and fixed in this recess.

The diameter of the porous member 8b is approximately the same as the diameter of the workpiece 1. The upper surface of the porous member 8b becomes the holding surface 8c. When the workpiece 1 is placed on the porous member 8b and the suction source is operated, negative pressure acts on the workpiece 1 through the suction path and the porous member 8b, and the workpiece 1 is held by suction on the chuck table 8.

The chuck table 8 is fixed on a table support 8d provided on the upper surface of the moving table 6. A rotation drive source 8e consisting of a motor or the like fixed on the moving table 6 is connected to the lower surface of the table support 8d via a spindle. When the rotation drive source 8e is operated, the chuck table 8 fixed to the table support 8d rotates around a table rotation axis 8f that intersects with the holding surface 8c.

As shown in FIG. 3, the holding surface 8c of the chuck table 8 is a conical surface with an extremely small inclination. The grinding device 2 is equipped with a support mechanism 8g that rotatably supports the chuck table 8 and allows the tilt to be adjusted. The support mechanism 8g has an inclination adjustment mechanism that has one or more fixed support parts and two or more movable support parts. By adjusting the height of the upper end of the movable support member, the holding surface 8c of the chuck table 8 can be inclined at a predetermined angle with respect to the vertical direction (Z-axis direction).

The grinding device 2 includes a grinding unit 24 that grinds the workpiece held by the chuck table 8, and a grinding feed unit 12 that raises and lowers the grinding unit 24. A support part 10 is erected on the rear side of the grinding device 2, and the grinding unit 24 is supported by this support part 10 via the grinding feed unit 12. A pair of guide rails 14 are provided on the front side of the support part 10 along the Z-axis direction (vertical direction). A lifting plate 16 is slidably attached to each guide rail 14.

A nut portion 18 is provided on the back side (rear side) of the lift plate 16, and a ball screw 20 parallel to the guide rail 14 is screwed into this nut portion 18. A pulse motor 22 is connected to one end of the ball screw 20. When the ball screw 20 is rotated by the pulse motor 22, the lift plate 16 moves in the Z-axis direction along the guide rail 14.

A grinding unit 24 that performs grinding processing on the workpiece 1 is fixed to the front side of the lift plate 16. By moving the lift plate 16, the grinding unit 24 can move in the Z-axis direction (grinding feed direction). The grinding unit 24 has a cut cylindrical holding member 26. The holding member 26 is fixed to the surface on the front side of the lift plate 16, and forms the exterior of the grinding unit 24.

A spindle housing 28 supported by the holding member 26 is provided inside the holding member 26. A portion of the spindle 30 is rotatably housed in the spindle housing 28. A rotation drive mechanism (not shown) such as a motor is connected to the upper end of the spindle 30. When the rotation drive mechanism is operated, the spindle 30 rotates around the rotation axis.

The lower end of the spindle 30 is located below the bottom of the holding member 26. The upper surface of a disk-shaped wheel mount 32 is connected to the lower end of the spindle 30. Figure 4 is a perspective view that shows a schematic diagram of how the grinding wheel 38 is fixed to the wheel mount 32.

The grinding wheel 38 has an annular wheel base 40. The wheel base 40 is made of a metal such as aluminum, and has a diameter corresponding to the diameter of the workpiece 1. A plurality of grinding wheels 42 arranged in a ring shape are provided on the outer periphery of the lower (bottom) surface side of the wheel base 40. Each grinding wheel 42 is formed by mixing abrasive grains such as diamond or cBN (cubic boron nitride) with a binder such as vitrified or resinoid, and sintering the mixture.

The wheel mount 32 has multiple grinding wheel fixing holes 34 that penetrate vertically, and the wheel base 40 has fastening holes 40a into which wheel fixing devices 36 such as bolts are fastened. When the wheel fixing device 36 is passed through the grinding wheel fixing holes 34 and fastened to the fastening holes 40a, the grinding wheel 38 is fixed to the wheel mount 32. At this time, the wheel mount 32 supports the grinding wheel 38 from above.

The grinding device 2 includes a thickness measurement unit 44 (see FIG. 3) provided on the base 4. The thickness measurement unit 44 includes, for example, a first probe 44a that contacts the top surface of the workpiece 1, a second probe 44b that contacts the holding surface 8c of the chuck table 8, and a shaft portion 44c that supports the first probe 44a and the second probe 44b. The thickness measurement unit 44 measures the height of the top surface of the workpiece 1 and the height of the holding surface 8c, and measures the thickness of the workpiece 1. However, the thickness measurement unit 44 is not limited to this.

When the workpiece 1 held by suction on the chuck table 8 is ground by the grinding unit 24, the rotary drive source connected to the spindle 39 is operated to rotate the spindle 30 around the wheel rotation axis 30a. This causes the grinding wheel 38 to rotate and the grinding stone 42 to move on the rotational orbit. In addition, the rotary drive source 8e is operated to rotate the chuck table 8 around the table rotation axis 8f.

Then, the grinding feed unit 12 is operated to lower the grinding unit 24, and the bottom surface of the grinding wheel 42 moving on the rotational orbit is brought into contact with the surface to be ground (rear surface 1b) of the workpiece 1. The workpiece 1 is then ground and gradually becomes thinner. At this time, the thickness measurement unit 44 monitors the thickness of the workpiece 1, and when the workpiece 1 reaches a predetermined thickness, the descent of the grinding unit 24 is terminated. Then, the workpiece 1 with the predetermined thickness is obtained.

If the relative inclination of the table rotation axis 8f and the wheel rotation axis 30a is not appropriate, the thickness distribution of the workpiece 1 after grinding will not be uniform, resulting in thickness bias and the front surface 1a and back surface 1b of the workpiece 1 after grinding not being parallel. Therefore, the inclination of the table rotation axis 8f, etc. is adjusted in advance so that the generatrix constituting the holding surface 8c, which is composed of a conical surface, that is closest to the rotation plane including the rotation orbit of the grinding wheel 42 is parallel to the rotation plane.

Figure 5 is a plan view showing a contact area 48 where the grinding wheel 42 comes into contact with the back surface 1b of the workpiece 1 when the table rotation axis 8f is appropriately adjusted. Figure 5 also shows a schematic of the workpiece 1 held by suction on the chuck table 8 and the rotational orbit 46 that is the path along which the grinding wheel 42 moves.

The rotation orbit 46 is set to pass through point 50b that overlaps with the center of the chuck table 8. The generatrix that constitutes the holding surface 8c of the chuck table 8 between point 50b and point 50a that overlaps with one end of the workpiece 1 on the rotation orbit 46 is parallel to the rotation orbit 46. In this case, the grinding wheel 42 moving along the rotation orbit 46 begins to contact the back surface 1b of the workpiece 1 when it reaches point 50a, and the grinding wheel 42 continues to contact the back surface 1b of the workpiece 1 until it reaches point 50b.

Then, the holding surface 8c moves away from the rotation orbit 46 from point 50b to point 50c where it overlaps with the other end of the workpiece 1 on the rotation orbit 46, so that the grinding wheel 42 passes point 50b and no longer comes into contact with the back surface 1b of the workpiece 1. Therefore, the back surface 1b of the workpiece 1 is ground by the grinding wheel 42 in the contact area 48. At this time, the chuck table 8 rotates around the table rotation axis 8f, and each part of the back surface 1b comes into contact with the contact area 48 one after another, so that the entire back surface 1b of the workpiece 1 is ground evenly.

Here, if the inclination of the table rotation axis 8f, etc. is inappropriate, the grinding wheel 42 may cut deeply into the workpiece 1 at point 50d, which is the midpoint between points 50a and 50b of the rotation orbit 46. Therefore, it is important that the distance between the holding surface 8c and the rotation orbit 46 is equal at all of points 50a, 50d, and 50b.

Adjustment of the inclination of the table rotation axis 8f, etc., is primarily performed, for example, during the initial setup stage of the grinding device 2 and during maintenance. To perform this adjustment, it is necessary to measure the distance between the rotation orbit 46 (wheel mount 32) and the holding surface 8c of the chuck table 8 at each point on the rotation orbit 46. Therefore, a height measuring device is connected to the wheel mount 32, and the height position of the holding surface 8c of the chuck table 8 is measured by the height measuring device.

Figure 6 is a side view showing a schematic diagram of how the height measuring device 54 is connected to the wheel mount 32. The height measuring device 54 is connected to the wheel mount 32 via a jig 56. The jig 56 has a function of realizing the movement of the height measuring device 54 along the rotation track 46 so that the height measuring device 54 measures the height of the holding surface 8c at each point of the area where the holding surface 8c overlaps with the rotation track 46.

The wheel mount 32 is provided with a height measuring device attachment mechanism 52 to which a height measuring device 54 can be attached via a jig 56. The height measuring device attachment mechanism 52 is, for example, a screw hole provided in the central bottom surface overlapping the spindle 30 of the wheel mount 32, and is screwed into a connection part 56a of the jig 56 having a thread, for example. The jig 56 has a shaft part 56b having a connection part 56a at its upper end, and an arm part 56c extending laterally from the shaft part 56b. The height measuring device 54 is fixed to the tip of the arm part 56c.

The height measuring device 54 may be fixed to the grinding wheel fixing hole 34 of the wheel mount 32. In this case, the grinding wheel fixing hole 34 functions as the height measuring device mounting mechanism. Below, an example will be described in which the height measuring device 54 is attached to the height measuring device mounting mechanism 52 that overlaps with the spindle 30 via a jig 56.

When the wheel mount 32 to which the jig 56 is connected is rotated, the height gauge 54 fixed to the tip of the arm 56c rotates around the wheel rotation axis 30a. At this time, it is preferable that the mounting position of the height gauge 54 on the arm 56c is set so that the distance from the wheel rotation axis 30a matches the radius of the rotation orbit 46 so that the height gauge 54 moves along the rotation orbit 46 of the grinding wheel 42.

Figure 7 is a side view showing a height measuring device 54 connected to the wheel mount 32 via a jig 56. Figure 8 is a plan view showing a height measuring device 54 moving along the rotational track 46.

The height measuring device 54 has a probe at its lower end, and can measure the height of the holding surface 8c at the contact point by contacting the probe with the holding surface 8c of the chuck table 8. The operator who adjusts the grinding device 2 rotates the wheel mount 32 to move the height measuring device 54 along the rotation track 46, switching the measurement point while measuring the height of each point of the holding surface 8c with the height measuring device 54. Then, the inclination of the table rotation axis 8f, etc. is adjusted based on the measurement results.

Here, the points on the holding surface 8c for which height measurement is particularly required to adjust the inclination of the table rotation axis 8f, etc., are the two ends of the holding surface 8c that overlap with the rotation track 46, the center of the holding surface 8c, and the two midpoints between the ends and the center. Explained with reference to FIG. 8, the height measuring device 54 is precisely positioned at points 50a, 50b, 50c, 50d, and 50e on the rotation track 46 to measure the height of the holding surface 8c.

The height measuring device 54 is moved to the specified position manually by the adjustment worker of the grinding device 2. That is, the adjustment worker moves the height measuring device 54 by rotating the wheel mount 32 by hand, and positions the height measuring device 54 at the specified position while visually checking the position of the height measuring device 54. Here, the adjustment worker needs to look into the gap between the wheel mount 32 and the chuck table 8 from the side in order to check the position of the height measuring device 54.

For example, when an adjustment worker performs a certain adjustment task above the grinding unit 24, each time the adjustment worker moves the height measuring device 54, he or she must move to a position where he or she can look into the gap and visually confirm the position of the height measuring device 54. This is a lot of work. Moreover, it is not easy to precisely detect the position of the height measuring device 54 from the side. Depending on the internal structure of the grinding device 2, the adjustment worker may have to visually check the gap from a distant position, in which case it is particularly difficult to precisely detect the position of the height measuring device 54.

Therefore, in the scaled plate and grinding device 2 according to this embodiment, the position of the height measuring device 54 can be easily and accurately determined without having to look into the gap between the chuck table 8 and the wheel mount 32 from the side. The explanation of the grinding device 2 will be continued below. In the grinding device 2 according to this embodiment, a scale is provided on one of the upper surface or side surface of the wheel mount 32 and the outer surface of the grinding unit 24 other than the wheel mount 32, and a mark pointing to a point on the scale is provided on the other.

For example, the scale is provided on the grinding device 2 by printing the scale on a plate and attaching the plate to the grinding device 2. FIG. 9(A) is a perspective view that shows a scale plate 58 with the scale printed thereon being attached to the upper surface of the wheel mount 32, and FIG. 10 is a plan view that shows the scale plate 58. Here, the scale plate 58 will be described in detail.

The graduated plate 58 is a sheet-like member made of a material such as metal, resin, or paper, and is, for example, a band-like member curved along the outer periphery of the upper surface of the wheel mount 32. The outer periphery of the graduated plate 58 is preferably formed by an arc with the same radius as the radius of the outer periphery of the upper surface of the wheel mount 32. In this case, the graduated plate 58 can be aligned in the radial direction of the wheel mount 32 by aligning the outer periphery of the graduated plate 58 with the outer periphery of the upper surface of the wheel mount 32.

The graduated plate 58 is provided with a scale 60. The scale 60 is composed of an arc-shaped axis 62 and a number of scale lines 64a, 64b, 64c, 64d, and 64e that are evenly spaced along the axis 62. The graduated plate 58 is also provided with an opening 70 that is long and extends along the outer periphery.

The scale plate 58 can be fixed to the upper surface of the wheel mount 32 using the grinding wheel fixing hole 34. For example, the scale plate 58 is placed on the upper surface of the wheel mount 32, and the grinding wheel fixing hole 34 is exposed in the opening 70. In this state, a fastener such as a bolt can be passed through the opening 70 and tightened into the grinding wheel fixing hole 34 to fix the scale plate 58 to the wheel mount 32.

Here, the opening 70 is formed long along the outer periphery of the graduated plate 58, so that the grinding wheel fixing hole 34 can be easily exposed in the opening 70 even if the graduated plate 58 is moved along the circumferential direction of the wheel mount 32. In other words, the graduated plate 58 can be fixed to the wheel mount 32 at any position within the range where the grinding wheel fixing hole 34 can be exposed in the opening 70. In other words, the worker can adjust the position to fix the graduated plate 58 to the wheel mount 32.

The following describes the markings 68 used in conjunction with the scale 60. For example, if the scale 60 is provided on the upper surface of the wheel mount 32, the markings 68 are provided on the outer surface of the grinding unit 24, excluding the wheel mount 32 and the spindle 30.

For example, the mark 68 is a triangular mark provided on the outer surface of the holding member 26 of the grinding unit 24, pointing to one point on the scale 60. However, the mark 68 is not limited to this, and does not have to be a dedicated mark provided solely for use in combination with the scale 60. The mark 68 may be any type of structure or pattern provided on the outer surface of the holding member 26 of the grinding unit 24. The person adjusting the grinding device 2 can use any structure as the mark 68.

Next, the fixed position of the scale plate 58 on the wheel mount 32 will be described. The adjustment worker positions the height gauge 54 attached to the wheel mount 32 by the height gauge attachment mechanism 52 and the jig 56 at one end of the holding surface 8c of the chuck table 8, and measures the height of the holding surface 8c on the spot using the height gauge 54.

Then, the position of the graduated plate 58 in the circumferential direction of the wheel mount 32 is adjusted so that, for example, the scale line 64a located at the end of the scale 60 of the graduated plate 58 is aligned with the mark 68. After that, a fastener is inserted into the grinding wheel fixing hole 34 exposed in the opening 70, and the graduated plate 58 is fixed to the wheel mount 32. Figure 9 (B) is a perspective view that shows a schematic of the graduated plate 58 fixed to the wheel mount 32. Note that the opening 70 and the fastener are omitted in Figure 9 (B) for ease of explanation.

Next, in order to measure the height at another location on the holding surface 8c, the spindle 30 is rotated to move the height measuring device 54. For example, if the spindle 30 is rotated 60° at this time, the height measuring device 54 is positioned at the center of the holding surface 8c. In other words, to position the height measuring device 54 at the center of the holding surface 8c, it is preferable to rotate the spindle 30 through a rotation angle of 60°.

The scale plate 58 is formed with a scale 60 that serves as an index for rotating the spindle 30 at a specified rotation angle. Here, the positions of the first scale line 64a, the second scale line 64b, and the third scale line 64c of the scale 60 provided on the scale plate 58 will be described. In addition, a method of aligning the height measuring device 54 using the scale 60 and the marks 68 will be described.

The second scale line 64b is provided on the graduated plate 58 so that when the spindle 30 is rotated 60°, the relative positional relationship between the second scale line 64b and the mark 68 coincides with the relative positional relationship between the first scale line 64a and the mark 68 before rotation. The third scale line 64c is provided on the graduated plate 58 so that when the spindle 30 is rotated 120°, the relative positional relationship between the third scale line 64c and the mark 68 coincides with the relative positional relationship between the first scale line 64a and the mark 68 before rotation.

In this case, when the spindle 30 is rotated 60°, the second scale line 64b reaches the position of the first scale line 64a before the rotation. Also, when the spindle 30 is rotated 120°, the third scale line 64c reaches the position of the first scale line 64a before the rotation.

Further explanation will be given using Figure 8. Figure 8 is a plan view that shows a schematic of the height gauge 54 moving along the rotation orbit 46 of the grinding wheel 42 and the chuck table 8. Here, the spindle 30 is rotated so that the second scale line 64b is aligned with the mark 68 to which the first scale line 64a was aligned before the rotation. Then, the height gauge 54, which was positioned at the end of the holding surface 8c (a position overlapping with point 50a of the rotation orbit 46) before the rotation, moves to the center of the holding surface 8c (a position overlapping with point 50b of the rotation orbit 46).

The spindle 30 is also rotated so that the third scale line 64c is aligned with the mark 68 to which the first scale line 64a was aligned before the rotation. Then, the height measuring device 54, which was positioned at the end of the holding surface 8c (a position overlapping with point 50a of the rotation orbit 46) before the rotation, moves to the other end of the holding surface 8c (a position overlapping with point 50c of the rotation orbit 46).

In this way, by rotating the spindle 30 while referring to the scale 60 and the mark 68, the height measuring device 54 can be moved to a specific position. Here, the scale 60 and the mark 68 are visible from outside the grinding unit 24 without having to look into the gap between the bottom surface of the wheel mount 32 and the holding surface 8c of the chuck table 8. Therefore, even a worker performing adjustment work above the grinding unit 24, for example, can position the height measuring device 54 at a specified position by rotating the spindle 30 while checking the scale 60 and the mark 68.

In addition, when peering into the gap to move the height measuring device 54 to the center of the holding surface 8c, the operator must visually determine the position of the center of the holding surface 8c from the side, making it difficult to ensure the accuracy of the alignment of the height measuring device 54. In contrast, with the grinding device 2 according to this embodiment, the height measuring device 54 is moved by aligning a specific scale line with the mark 68, so the operator does not need to determine the movement target. This improves the accuracy of the alignment of the height measuring device 54.

Furthermore, the fourth scale line 64d and the fifth scale line 64e will be described. The fourth scale line 64d is provided so that when the spindle 30 is rotated 30°, the relative positional relationship between the fourth scale line 64d and the mark 68 coincides with the relative positional relationship between the first scale line 64a and the mark 68 before rotation. The fifth scale line 64e is provided so that when the spindle 30 is rotated 90°, the relative positional relationship between the fifth scale line 64e and the mark 68 coincides with the relative positional relationship between the first scale line 64a and the mark 68 before rotation.

When the scale 60 is attached to the wheel mount 32, when the spindle 30 is rotated 30°, the fourth scale line 64d reaches the position of the first scale line 64a before the rotation. When the spindle 30 is rotated 90°, the fifth scale line 64e reaches the position of the first scale line 64a before the rotation. The fourth scale line 64d and the fifth scale line 64e are used to position the height gauge 54 at the midpoint between the center and the end of the holding surface 8c. This will be further explained using Figure 8.

For example, the spindle 30 is rotated so that the fourth scale line 64d is aligned with the mark 68 to which the first scale line 64a was aligned before the rotation. Then, the height measuring device 54, which was positioned at the end of the holding surface 8c (a position overlapping with point 50a of the rotation orbit 46) before the rotation, moves to one of the midpoints on the holding surface 8c (a position overlapping with point 50d of the rotation orbit 46).

The spindle 30 is also rotated so that the fifth scale line 64e is aligned with the mark 68 to which the first scale line 64a was aligned before the rotation. Then, the height measuring device 54, which was positioned at the end of the holding surface 8c (a position overlapping with point 50a of the rotation orbit 46) before the rotation, moves to the other midpoint on the holding surface 8c (a position overlapping with point 50e of the rotation orbit 46).

So far, we have described a case where the height measuring device 54 is first positioned at the end of the holding surface 8c, and the scaled plate 58 is fixed so that the first scale line 64a is aligned with the mark 68. However, the arrangement position of the scale 60 on the wheel mount 32, i.e., the fixing position of the scaled plate 58, is not limited to this. For example, the scaled plate 58 may be fixed to the wheel mount 32 before the height measuring device 54 is positioned at a specific position.

In this case, for example, when the height measuring device 54 is positioned at the end of the holding surface 8c, the mark 68 may point between the first graduation line 64a and the fourth graduation line 64d of the scale 60. Even in this case, the height measuring device 54 can be positioned in the center of the holding surface 8c by rotating the spindle 30 so that the mark 68 points between the second graduation line 64b and the fifth graduation line 64e.

In this way, even if the scale 60 is attached to the wheel mount 32 regardless of the position of the height measuring device 54, the scale 60 and the markings 68 can be used to position the height measuring device 54 at a predetermined position.

The scale 60 may be provided over a wider area of the wheel mount 32 and may have additional scale lines so that the scale 60 can be used regardless of where the height measuring device 54 is located on the rotational track 46. For example, the scale 60 may be provided over the entire circumference of the wheel mount 32. In this case, the adjustment worker uses any of the scale lines that make up the scale 60 to position the height measuring device 54 at a predetermined position.

Furthermore, the scale 60 may be printed directly on the top or side of the wheel mount 32, rather than on the scale plate 58. FIG. 9(C) is a perspective view showing a wheel mount 32 on which a scale 60a including multiple scale lines 66a, 66b, 66c, 66d, and 66e is printed directly on the top surface. Each of the scale lines 66a, 66b, 66c, 66d, and 66e is arranged in the same manner as the scale lines 64a, 64b, 64c, 64d, and 64e shown in FIG. 9(A) and is used in the same manner.

The scales 60, 60a do not necessarily have to have an axis 62, and may be composed of only a number of scale lines. The scale 60a shown in FIG. 9(C) does not have an axis 62. The axis 62 does not necessarily contribute to the alignment of the height measuring device 54, and therefore may be omitted.

As described above, in the grinding device 2 according to this embodiment, the position of the height measuring device 54 on the holding surface 8c can be detected by reading the point on the scale 60, 60a indicated by the mark 68, and highly accurate alignment of the height measuring device 54 can be easily achieved.

The scale plate 58 with the scale 60 can be easily attached to an existing grinding device 2. After measuring the height of each point on the holding surface 8c of the chuck table 8 and adjusting the table rotation axis 8f, etc., it can be easily removed from the grinding device 2 and can be used for adjustment work on other grinding devices 2.

The size of the workpiece 1 to be ground is not constant. A grinding device 2 equipped with a chuck table 8 and a grinding wheel 38 having a holding surface 8c corresponding to the diameter of the surface to be ground of the workpiece 1 is selected and used for grinding the workpiece 1. Therefore, it is preferable to prepare a graduated plate 58 with a configuration applicable to various grinding devices 2 so that adjustments of the table rotation axis 8f, etc. can be easily performed in various grinding devices 2.

Specifically, it is preferable to prepare multiple graduated plates 58 with different intervals between the graduation lines. In this case, the graduated plate 58 corresponding to the grinding device 2 can be attached to any grinding device 2. The graduated plate 58 only needs to be able to be attached to the grinding device 2 in a manner that allows it to perform the specified function.

In other words, it is preferable that the graduated plate 58 can be attached to the grinding device 2 so that when the spindle 30 is rotated 60°, the relative positional relationship between the second graduation line 64b and the mark 68 coincides with the relative positional relationship between the first graduation line 64a and the mark 68 before the rotation. Also, it is preferable that the graduated plate 58 can be attached to the grinding device 2 so that when the spindle 30 is rotated 120°, the relative positional relationship between the third graduation line 64c and the mark 68 coincides with the relative positional relationship between the first graduation line 64a and the mark 68 before the rotation.

The graduated plate 58 may be attached to the grinding device 2 so that when the spindle 30 is rotated 30°, the relative positional relationship between the fourth scale line 64d and the mark 68 coincides with the relative positional relationship between the first scale line 64a and the mark 68 before the rotation. The graduated plate 58 may be attached to the grinding device 2 so that when the spindle 30 is rotated 90°, the relative positional relationship between the fifth scale line 64e and the mark 68 coincides with the relative positional relationship between the first scale line 64a and the mark 68 before the rotation.

The present invention is not limited to the above embodiment, and can be modified in various ways. For example, the above embodiment describes a case where the scaled plate 58 can be fixed to the grinding device 2 by a fastener that is passed through the grinding wheel fixing hole 34 of the wheel mount 32. However, the grinding device 2 and scaled plate 58 according to one aspect of the present invention are not limited to this.

The graduated plate 58 may be fixed to the grinding device 2 by tape or a magnet, or may be fixed to the grinding device 2 by tape or a magnet. There are no particular limitations on the method of fixing the graduated plate 58.

In addition, in the above embodiment, the explanation was centered on the case where the scale 60 is provided on the upper surface of the wheel mount 32, but the grinding device 2 according to one aspect of the present invention is not limited to this. In other words, the scale 60 may be provided on the side of the wheel mount 32 that is visible from the outside.

In addition, while the above description has focused on a case where the scale 60 is provided on the wheel mount 32 and the mark 68 is provided on the outer surface of the holding member 26 of the grinding unit 24, the grinding device 2 and the scaled plate 58 according to one aspect of the present invention are not limited to this. The scale 60 may be provided on the outer surface of the grinding unit 24 excluding the wheel mount 32 and the spindle 30, and the mark 68 may be provided on the top or side surface of the wheel mount 32.

What is important here is that one of the scale 60 and the mark 68 is provided on the element that moves when the spindle 30 is rotated, and the other of the scale 60 and the mark 68 is provided on the element that does not move when the spindle 30 is rotated. In this way, the scale 60 and the mark 68 function as an indication of the rotation angle of the spindle 30. And, if the worker can visually confirm the positional relationship between the scale 60 and the mark 68, the worker can position the height measuring device 54 in the specified position.

Furthermore, in the above embodiment, a case has been described in which the scale 60 is provided on the wheel mount 32 so that the first scale line 64a aligns with the mark 68, and the second scale line 64b aligns with the mark 68 when the spindle 30 is rotated 60°. Also, a case has been described in which the third scale line 64c aligns with the mark 68 when the spindle 30 is rotated 120°, the fourth scale line 64d aligns with the mark 68 when the spindle 30 is rotated 30°, and the fifth scale line 64e aligns with the mark 68 when the spindle 30 is rotated 90°. However, one aspect of the present invention is not limited to this.

Depending on the configuration of the grinding device 2, such as the chuck table 8, wheel mount 32, grinding wheel 38, height gauge 54, and jig 56, it may not be possible to precisely position the height gauge 54 at a predetermined measurement point by rotating the spindle 30 at a predetermined angle. Also, depending on the position of the measurement point on the holding surface 8c at which the height measurement by the height gauge 54 is intended, it may not be possible to precisely position the height gauge 54 at a predetermined measurement point by rotating the spindle 30 at a predetermined angle.

In order to align the height measuring device 54 with higher precision using the scale 60 provided on the grinding device 2, the position of each graduation line constituting the scale 60 may be determined by the method described below.

That is, first, a blank plate without graduation lines is fixed to the upper surface of the wheel mount 32. A mark 68 of a predetermined shape is provided on the outer surface of the holding member 26 that forms the exterior of the grinding unit 24. Then, the height gauge 54 attached to the wheel mount 32 via a jig 56 by the height gauge attachment mechanism 52 is positioned at a measurement point on the end of the holding surface 8c of the chuck table 8. At this time, a first graduation line 64a is written at the point on the plate indicated by the mark 68.

Next, look into the gap between the wheel mount 32 and the holding surface 8c from the side, and rotate the spindle 30 to position the height gauge 54 at the measurement point in the center of the holding surface 8c. At this time, a second scale line 64b is written at the point on the plate indicated by the mark 68. Furthermore, look into the gap between the wheel mount 32 and the holding surface 8c from the side, and rotate the spindle 30 to position the height gauge 54 at the measurement point on the other end of the holding surface 8c. At this time, a third scale line 64c is written at the point on the plate indicated by the mark 68.

Similarly, while directly observing the gap, the height measuring device 54 is moved to a predetermined measurement point on the holding surface 8c, and a fourth scale line 64d and a fifth scale line 64e are written on the point on the plate indicated by the mark 68 at this time. This allows the production of a graduated plate 58 on which the scale 60 is written.

Here, in the produced graduated plate 58, it is possible that after the spindle 30 is rotated so that the mark 68 aligns with the first graduation line 64a, the second graduation line 64b will not exactly align with the mark 68 even if the spindle 30 is rotated 60°. It is also possible that the third graduation line 64c will not exactly align with the mark 68 even if the spindle 30 is rotated 120°. However, when the spindle 30 is rotated so that each of the graduation lines 64b, 64c, 64d, and 64e aligns with the mark 68, the height measuring device 54 is precisely positioned at the measurement point.

In this way, rather than creating the scale 60 based on the rotation angle of the spindle 30, creating the scale 60 by recreating the actual usage situation may be advantageous in terms of providing precise alignment of the height measuring device 54 and fulfilling the function of the scale 60. Therefore, in one aspect of the present invention, even when the positional relationship of each graduation line constituting the scale 60 is expressed by the number of the rotation angle of the spindle 30, a slight deviation of each graduation line from the positional relationship expressed by the number is permissible, and in some cases such deviation may even be preferable.

In other words, even when the positional relationship of each scale line is expressed by the number of the rotation angle of the spindle 30, the number does not necessarily strictly define the positional relationship of each scale line, and attention is focused on the actual function of each scale line. Therefore, even if the grinding device 2 and the graduated plate 58 are provided with a scale where the scale lines do not strictly satisfy the positional relationship defined by the number, this alone does not exclude them from being a grinding device 2 and a graduated plate 58 according to one aspect of the present invention.

In the above embodiment, the scale 60 is used to move the height measuring device 54 to each measurement point of the two ends, the center, and the midpoint between the ends and the center of the holding surface 8c to measure the height of the holding surface 8c. However, one aspect of the present invention is not limited to this.

That is, the height measuring device 54 may measure the height of the holding surface 8c at other measurement points. In this case, it is preferable that the scale 60 includes a scale line for positioning the height measuring device 54 at the other measurement point. Therefore, in the grinding device 2 and the scaled plate 58 according to one aspect of the present invention, the scale 60 may further include scale lines other than the scale lines 64a, 64b, 64c, 64d, and 64e. The scale 60 is provided with scale lines corresponding to the distribution of the measurement points of the holding surface 8c.

However, if there are too many scale lines, the person adjusting the grinding device 2 may be confused as to which scale line to refer to, or may make an incorrect decision. Therefore, it may be preferable in some cases that the scale 60 does not include scale lines other than the scale lines 64a, 64b, 64c, 64d, and 64e. Furthermore, it may be preferable in some cases that the scale 60 does not include scale lines other than the first scale line 64a, the second scale line 64b, and the third scale line 64c.

In the above embodiment, the holding surface 8c of the chuck table 8 is described as being conical, but the grinding device 2 according to one aspect of the present invention is not limited to this. In other words, the holding surface 8c may be flat.

In some types of grinding devices 2, a chuck table 8 with a flat holding surface 8c may be used. Even in this case, it is desirable to measure the height of the holding surface 8c at a predetermined position with a height measuring device 54 and adjust the inclination of the table rotation axis 8f. In the grinding device 2 and scaled plate 58 of this embodiment, the scale 60 and mark 68 can be used to position the height measuring device 54 at a predetermined position, even when the holding surface 8c is a flat surface.

The structures, methods, etc. of the above embodiments can be modified as appropriate without departing from the scope of the present invention.

REFERENCE SIGNS LIST 1 workpiece 1a front surface 1b back surface 3 protective member 2 grinding device 4 base 4a recess 4b dust-proof/water-proof cover 6 moving table 8 chuck table 8a frame 8b porous member 8c holding surface 8d table support 8e rotation drive source 8f table rotation shaft 8g support mechanism 10 support section 12 grinding feed unit 14 guide rail 16 lift plate 18 nut section 20 ball screw 22 pulse motor 24 grinding unit 26 holding member 28 spindle housing 30 spindle 30a wheel rotation shaft 32 wheel mount 34 grinding wheel fixing hole 36 wheel fixing device 38 grinding wheel 40 wheel base 40a fastening hole 42 grinding wheel 44 thickness measurement unit 44a, 44b Probe 44c Shaft 46 Rotation orbit 48 Contact area 50a, 50b, 50c, 50d, 50e Point 52 Height gauge attachment mechanism 54 Height gauge 56 Jig 56a Connection 56b Shaft 56c Arm 58 Scale plate 60 Scale 62 Axis 64a, 64b, 64c, 64d, 64e Scale lines 66a, 66b, 66c, 66d, 66e Scale lines 68 Mark 70 Opening

Claims (10)

a chuck table having a holding surface on an upper surface thereof for suction-holding a disk-shaped workpiece on the holding surface;
a grinding unit that includes a rotatable spindle that can be raised and lowered by a grinding feed unit, and a wheel mount that is connected to a lower end of the spindle and can detachably support a grinding wheel having grinding stones arranged in an annular shape on a bottom surface thereof, and that grinds the workpiece held on the chuck table;
a grinding device capable of grinding the workpiece by rotating the grinding wheel attached to the wheel mount, lowering the grinding unit, and bringing the grinding stone into contact with the workpiece held on the holding surface of the chuck table,
the wheel mount is provided with a height gauge attachment mechanism capable of attaching a height gauge that measures a height position of the holding surface of the chuck table relative to the wheel mount;
a scale is provided on one of an upper surface or a side surface of the wheel mount and an outer surface of the grinding unit other than the wheel mount and the spindle, which does not move even when the spindle is rotated, and a mark indicating a point on the scale is provided on the other of the upper surface or a side surface of the wheel mount and the outer surface of the grinding unit other than the spindle;
the height gauge attached to the wheel mount by the height gauge attachment mechanism is moved along the rotational orbit of the grinding wheel on the holding surface of the chuck table, and the height position of each point on the holding surface can be measured by the height gauge;
A grinding apparatus characterized in that the position of the height measuring device on the holding surface along the rotational orbit can be detected by reading the point on the scale that the mark indicates. 2. The grinding device according to claim 1, wherein the scale is printed on a plate attached to one of the top or side surface of the wheel mount and an outer surface of the grinding unit other than the wheel mount and the spindle that does not move even when the spindle is rotated . The wheel mount is formed with a grinding wheel fixing hole through which a wheel fixing tool for fixing the grinding wheel to the wheel mount is passed,
3. The grinding apparatus according to claim 2, wherein one of the plate and the mark is fixable by a fastener that is passed through the grinding wheel fixing hole. 2. The grinding device according to claim 1, wherein the scale is printed on one of the top or side surface of the wheel mount and an outer surface of the grinding unit other than the wheel mount and the spindle that does not move when the spindle is rotated . the scale includes a first scale line, a second scale line, and a third scale line;
when the spindle is rotated by 60°, the relative positional relationship between the second scale mark and the mark coincides with the relative positional relationship between the first scale mark and the mark before the rotation;
5. The grinding device according to claim 1, wherein, when the spindle is rotated by 120 degrees, a relative positional relationship between the third scale line and the mark coincides with a relative positional relationship between the first scale line and the mark before the rotation. the scale further includes a fourth scale line and a fifth scale line;
when the spindle is rotated by 30°, a relative positional relationship between the fourth scale line and the marking coincides with a relative positional relationship between the first scale line and the marking before the rotation;
6. The grinding apparatus according to claim 5, wherein when the spindle is rotated by 90 degrees, a relative positional relationship between the fifth scale line and the mark coincides with a relative positional relationship between the first scale line and the mark before the rotation. a chuck table having a holding surface on an upper surface thereof for suction-holding a disk-shaped workpiece on the holding surface;
a grinding unit that includes a rotatable spindle that can be raised and lowered by a grinding feed unit, and a wheel mount that is connected to a lower end of the spindle and can detachably support a grinding wheel having grinding stones arranged in an annular shape on a bottom surface thereof, and that grinds the workpiece held on the chuck table;
a scale plate which can be attached to one of an upper surface or a side surface of the wheel mount and an outer surface of the grinding unit other than the wheel mount and the spindle of a grinding device capable of grinding a workpiece held on the holding surface of the chuck table by rotating the grinding wheel attached to the wheel mount, lowering the grinding unit, and bringing the grinding wheel into contact with the workpiece held on the holding surface of the chuck table, and which can be used in combination with a mark provided on the other of the upper surface or the side surface of the wheel mount and the outer surface of the grinding unit other than the wheel mount and the spindle,
The scale is printed,
the scale includes a first scale line, a second scale line, and a third scale line;
a scale plate that can be attached to the grinding device such that, when the spindle is rotated 60 degrees, a relative positional relationship between the second scale line and the mark coincides with a relative positional relationship between the first scale line and the mark before the rotation, and such that, when the spindle is rotated 120 degrees, a relative positional relationship between the third scale line and the mark coincides with a relative positional relationship between the first scale line and the mark before the rotation. the scale further includes a fourth scale line and a fifth scale line;
8. The graduated plate according to claim 7, wherein the graduated plate can be attached to the grinding device such that when the spindle is rotated 30°, a relative positional relationship between the fourth scale line and the mark coincides with a relative positional relationship between the first scale line and the mark before the rotation, and such that when the spindle is rotated 90°, a relative positional relationship between the fifth scale line and the mark coincides with a relative positional relationship between the first scale line and the mark before the rotation. a grinding wheel fixing hole through which a wheel fixing tool for fixing the grinding wheel to the wheel mount is inserted is formed in the wheel mount of the grinding device;
9. The graduated plate according to claim 7 or 8, characterized in that it can be fixed to the grinding device by a fastener that is passed through the grinding wheel fixing hole. The graduated plate according to claim 7 or 8, characterized in that it can be fixed to the grinding device by tape or a magnet.

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