Dressing method, dressing device, and grindstone

Abstract

To provide a dressing method capable of finely adjusting grinding performance of a grindstone, a dressing device, and a grindstone.SOLUTION: The dressing method holds a grindstone G formed by binding abrasives by a binder in a state where a grinding surface Gf of the grindstone G is exposed, condenses a laser beam LA1 to apply it to the grinding surface Gf, and moves an irradiation region of the grinding surface Gf irradiated with the laser beam LA1, thereby melting and evaporating the binder to adjust a protruding amount of the abrasives. Then, by changing the intensity of the laser beam LA1, the protruding amount of the abrasives in the grinding surface Gf of the grindstone G is adjusted.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a dressing method, a dressing device, and a grinding wheel. [Background technology]

[0002] A non-contact dressing and truing method for grinding wheels has been proposed in which the binder on the grinding surface or auxiliary grinding surface of a grinding wheel that requires dressing or truing is melted and evaporated, thereby controlling the amount of abrasive grain protrusion and the grinding wheel contour (see, for example, Patent Document 1). In this non-contact dressing and truing method for grinding wheels, a laser is irradiated from a laser oscillator onto the grinding surface or auxiliary grinding surface of the grinding wheel, melting and evaporating the binder on the grinding surface or auxiliary grinding surface of the grinding wheel, thereby controlling the amount of abrasive grain protrusion and the grinding wheel contour. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-285971 Summary of the Invention [Problem to be solved by the invention]

[0004] In dressing and truing a grinding wheel, it is sometimes required to finely adjust the grinding performance of the wheel depending on the application of the wheel. In this case, the non-contact dressing and truing method of a grinding wheel described in Patent Document 1 may not be able to sufficiently control the abrasive grain protrusion amount so as to obtain the required grinding performance of the wheel.

[0005] The present invention has been made in view of the above-mentioned circumstances, and has an object to provide a dressing method, a dressing device, and a grinding wheel that can finely adjust the grinding performance of the grinding wheel. [Means for solving the problem]

[0006] In order to achieve the above object, a dressing method according to the present invention comprises: A dressing method for adjusting the protrusion amount of the abrasive grains by holding a grinding wheel, which is made of abrasive grains bonded with a binder, with a grinding surface of the grinding wheel exposed, and irradiating the grinding surface with a laser beam to melt and evaporate the binder, comprising: The intensity of the laser light is changed to adjust the protrusion amount on the grinding surface.

[0007] The dressing device according to the present invention from another aspect comprises: a grinding wheel holder that holds a grinding wheel made of abrasive grains bonded together with a binder, with the grinding surface of the grinding wheel exposed; a laser head that condenses a laser beam so that an area of ​​an irradiation region on the grinding surface where the laser beam is irradiated is smaller than an area of ​​the grinding surface; and a head attitude changing unit that changes the attitude of the laser head to change the radiation direction of the laser light, thereby moving the irradiation area on the grinding surface; and a control unit that controls the head attitude changing unit to move the irradiation area on the grinding surface, and controls the laser head to change the intensity of the laser light, thereby adjusting the amount of protrusion of the abrasive grains on the grinding surface. [Effects of the Invention]

[0008] According to the present invention, the amount of protrusion of the abrasive grains from the grinding surface of the grinding wheel is adjusted by changing the intensity of the laser light, thereby enabling the grinding performance of the grinding wheel to be finely adjusted. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram of a dressing device according to an embodiment of the present invention. [Figure 2](A) is a diagram showing the average protrusion amount of abrasive grains on the grinding wheel surface when dressed using the dressing method of the embodiment and the dressing method of the comparative example, (B) is a diagram showing the change in surface roughness of the inner wall of a machining hole when a workpiece is honed using a grinding wheel dressed using the dressing method of the comparative example, and (C) is a diagram showing the change in surface roughness of the inner wall of a machining hole when a workpiece is honed using a grinding wheel dressed using the dressing method of the embodiment. [Figure 3] 10 is a diagram showing the magnitude of variation in protrusion of abrasive grains when dressing is performed by the dressing method according to the embodiment and the dressing method according to the comparative example. FIG. [Figure 4] FIG. 1A is a diagram showing the change in torque required when honing a workpiece using a grinding wheel dressed by a dressing method according to an embodiment, and FIG. 1B is a diagram showing the change in surface roughness of the inner wall of a machining hole when honing a workpiece using a grinding wheel dressed by a dressing method according to an embodiment. [Figure 5] FIG. 2A is a diagram showing an example of a grinding wheel dressed by the dressing method according to the embodiment, and FIG. 2B is a diagram showing another example of a grinding wheel dressed by the dressing method according to the embodiment. [Figure 6] FIG. 10 is a diagram showing the change in surface roughness of the inner wall of a machining hole when a workpiece is honed using a grindstone dressed by the dressing method according to the embodiment. [Figure 7] FIG. 10 is a diagram showing the change in surface roughness of the inner wall of a machining hole when a workpiece is honed using a grindstone dressed by the dressing method according to the embodiment. [Figure 8] 1A and 1B are diagrams for explaining a dressing method according to an embodiment, in which (A) shows the case of Example 2 and (B) shows the case of Example 3. FIG. [Figure 9] FIG. 10 is a schematic configuration diagram of a dressing device according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] A dressing method according to an embodiment of the present invention will be described below with reference to the drawings. In this dressing method, a grinding wheel made of abrasive grains bonded with a binder is held with its grinding surface exposed, and a laser beam is focused and irradiated onto the grinding surface so that the area of ​​the irradiated region on the grinding surface is at least smaller than the area of ​​the grinding surface. The irradiated region on the grinding surface is moved to melt and vaporize the binder, thereby adjusting the protrusion amount of the abrasive grains. In this dressing method, the intensity of the laser beam is changed while the irradiated region on the grinding surface is moved, thereby forming multiple regions on the grinding surface with different average protrusion amounts of the abrasive grains.

[0011] As shown in Fig. 1, the dressing device according to this embodiment includes a grinding wheel holder 11, a laser head 12, a head attitude changer 13, a control unit 21, and a terminal device 22. The grinding wheel holder 11 holds the grinding wheel G with its grinding surface Gf exposed. The grinding wheel G is a metal-bonded grinding wheel, a ceramic-bonded grinding wheel, or the like. The grinding wheel G is made of a plurality of abrasive grains bonded together with a binder. Here, the abrasive grains that can be used include single-crystal diamond, polycrystalline diamond, single-crystal cubic boron nitride, polycrystalline cubic boron nitride, and the like. This grinding wheel G has, for example, a long grinding surface Gf in a plan view, and is attached to the tip of a long honing tool that hones the inner surface of a machining hole in a workpiece, with the longitudinal direction of the grinding surface Gf aligning with the longitudinal direction of the honing tool.With the grinding surface Gf in contact with the inner surface of the machining hole in the workpiece, the honing tool is rotated around its central axis along the longitudinal direction of the honing tool, causing the grinding surface Gf to slide in the short direction to grind the inner surface of the machining hole.

[0012] The laser head 12 is disposed so that the irradiation port of the laser beam LA1 faces the grinding wheel holding part 11, and irradiates the grinding surface Gf with the laser beam LA1 by concentrating the laser beam LA1 so that the area of ​​the irradiation region on the grinding surface Gf is at least smaller than the area of ​​the grinding surface Gf. The laser head 12 has, for example, a YAG laser pumped dye laser oscillator, a YAG laser oscillator, or the like.

[0013] The head attitude changing unit 13 changes the radiation direction of the laser beam LA1 by changing the attitude of the laser head 12. The head attitude changing unit 13 moves the irradiation area, onto which the laser beam LA1 is irradiated, on the grinding surface Gf of the grinding wheel G held by the grinding wheel holding unit 11 by changing the attitude of the laser head 12, as shown by an arrow AR1.

[0014] The control unit 21 includes, for example, a programmable logic controller (PLC) and controls the laser head 12 and the head position change unit 13 based on setting information set by a user via a terminal device 22. The control unit 21 controls the head position change unit 13 to move the irradiation area of ​​the laser beam LA1 on the grinding surface Gf of the grinding wheel G, while controlling the laser head 12 to change the intensity of the laser beam LA1, thereby forming multiple areas with different abrasive grain protrusion amounts on the grinding surface Gf of the grinding wheel G. The control unit 21 includes a correlation information storage unit (not shown) that stores correlation information indicating the correlation between the intensity of the laser beam LA1 and the abrasive grain protrusion amount. The control unit 21 determines the intensity of the laser beam LA1 to be irradiated from the laser head 12 onto the grinding surface Gf of the grinding wheel G based on the correlation information and setting information indicating the set value of the abrasive grain protrusion amount set by the user via the terminal device 22. The control unit 21 then controls the laser head 12 so that the laser beam LA1 of the determined intensity is output from the laser head 12.

[0015] Here, the characteristics of the dressing method according to the present embodiment will be described in comparison with a dressing method according to a comparative example. Here, we will describe the case where the grinding surface of a grinding wheel having a long grinding surface is dressed. In the dressing method according to the comparative example, a cylindrical grinder, in which abrasive grains finer than the abrasive grains of the grinding wheel are embedded in the contact surface with the grinding wheel, is rotated and brought into contact with the grinding surface of the grinding wheel while sliding along the longitudinal direction of the grinding surface, thereby performing dressing. FIG. 2A shows a comparison of the average protrusion amount Rz of the abrasive grains on the grinding surface when the grinding surfaces of four grinding wheels are dressed using the dressing method according to the comparative example and the dressing method according to the present embodiment. As shown in FIG. 2A, in the case of the dressing method according to the comparative example, the average protrusion amount of the abrasive grains of the four grinding wheels was greater than 12 μm, and the variation in the protrusion amount was approximately 5 μm. In contrast, with the dressing method according to the present embodiment, the average protrusion amount of the abrasive grains of the four grinding wheels could be reduced to approximately 10 μm, and the variation in the protrusion amount could be reduced to approximately 1 μm. Furthermore, when a workpiece was honed using each of the four grinding wheels dressed using the dressing method according to the comparative example, the surface roughness Rzw of the inner wall of the workpiece's drilled hole varied by more than 2 μm, as shown in FIG. 2(B). Note that in FIG. 2(B), the results of honing using each of the four grinding wheels dressed using the dressing method according to the comparative example are shown by circles with different shading. On the other hand, when a workpiece was honed using each of the four grinding wheels dressed using the dressing method according to the present embodiment, the surface roughness Rzw of the inner wall of the workpiece's drilled hole varied by less than 1.5 μm, as shown in FIG. 2(C). In FIG. 2(C), the results of honing using each of the four grinding wheels dressed by the dressing method according to the present embodiment are shown by diamond marks and rectangular marks of different shading or size.3, the variation Rzv in the protrusion amount across the entire grinding surface of the grinding wheel dressed using the dressing method of the comparative example was approximately 55 μm, whereas the variation Rzv in the protrusion amount across the entire grinding surface of the grinding wheel dressed using the dressing method of the present embodiment was approximately 25 μm. From the above results, it can be seen that by adopting the dressing method of the present embodiment, the protrusion amount of the grinding wheel can be reduced compared to when the dressing method of the comparative example is adopted, and the variation in the protrusion amount between multiple grinding wheels when multiple grinding wheels are dressed can also be reduced. It can also be seen that the variation in the protrusion amount of the abrasive grains across the entire grinding surface of the grinding wheel can be reduced.

[0016] Incidentally, increasing the protrusion length of the abrasive grains of the grinding wheel to improve the grinding power of the grinding wheel correspondingly reduces the torque required to rotate a honing tool with the grinding wheel attached to its tip. On the other hand, increasing the protrusion length of the abrasive grains of the grinding wheel correspondingly increases the surface roughness of the inner wall of a workpiece hole when honed with the grinding wheel. For example, as shown in FIG. 4(A), the torque required to rotate a honing tool with the grinding wheel of Example A attached to its tip is smaller than the torque required to rotate a honing tool with the grinding wheel of Example B, which has a smaller protrusion length of the abrasive grains than Example A. On the other hand, as shown in FIG. 4(B), the surface roughness of the inner wall of a workpiece hole when honed with the grinding wheel of Example A is greater than the surface roughness of the inner wall of a workpiece hole when honed with the grinding wheel of Example B, which has a smaller protrusion length of the abrasive grains than Example A. For example, if the torque required to rotate a honing tool with a grinding wheel attached to its tip is excessively large and a torque error occurs in a honing device equipped with the honing tool, it is necessary to adjust the protrusion amount of the abrasive grains of the grinding wheel to increase the grinding power of the grinding wheel. On the other hand, if the surface roughness of the inner wall of a hole in a workpiece when honed using the grinding wheel exceeds the upper limit of the standard surface roughness required for the inner wall of the hole, it is necessary to adjust the protrusion amount of the abrasive grains of the grinding wheel to decrease the protrusion amount. Thus, the protrusion amount of the abrasive grains of the grinding wheel must be finely adjusted based on the capacity of the honing device and the standard surface roughness required for the inner wall of the hole in the workpiece.

[0017] Therefore, in the dressing method according to the present embodiment, the intensity of the laser beam LA1 is changed while the irradiation area of ​​the laser beam LA1 on the grinding surface Gf of the grinding wheel G is moved, thereby forming a plurality of regions with different average protrusion amounts on the grinding surface Gf of the grinding wheel G. Here, as shown in Fig. 5(A), for example, the plurality of regions are composed of a first region Gf1 extending in a direction intersecting the short side direction on the grinding surface Gf of the grinding wheel G1, and a second region Gf2 on the grinding surface Gf other than the first region Gf1, and the grinding wheel G is dressed so that the average protrusion amount of the abrasive grains in the first region Gf1 is larger than the average protrusion amount of the abrasive grains in the second region Gf2. 5(B), the aforementioned multiple regions are composed of a first region Gf1 that includes one entire short-side end of the grinding surface Gf of the grinding wheel G2 and extends over the entire longitudinal direction of the grinding surface Gf, and a second region Gf2 on the grinding surface Gf other than the first region Gf1, and the grinding wheel G is dressed so that the average protrusion amount of the abrasive grains in the first region Gf1 is larger than the average protrusion amount of the abrasive grains in the second region Gf2. Here, the ratio of the area of ​​the first region Gf1 to the area of ​​the entire grinding surface Gf can be 45% or more and 62% or less.

[0018] Here, the surface roughness of the inner wall of a workpiece hole when honing a workpiece using a grinding wheel according to Example 1, in which the protrusion amount of abrasive grains is uniform across the entire grinding surface Gf of the grinding wheel G, a grinding wheel according to Example 2 having the grinding surface Gf shown in FIG. 5(A), and a grinding wheel according to Example 3 having the grinding surface Gf shown in FIG. 5(B), is compared. The grinding wheel according to Example 1 was dressed so that the average protrusion amount of abrasive grains across the entire grinding surface Gf was the same as the average protrusion amount of abrasive grains in the first region Gf1 of the grinding surface Gf of the grinding wheels according to Examples 2 and 3. The grinding wheels according to Examples 2 and 3 were also dressed so that the average protrusion amount of abrasive grains in the second region Gf2 was the same. As shown in FIG. 6, the surface roughness of the inner wall of a workpiece hole when honing a workpiece using the grinding wheels according to Examples 2 and 3 was smaller than the surface roughness of the inner wall of a workpiece hole when honing a workpiece using the grinding wheel according to Example 1. Furthermore, when the grinding wheel according to Example 3 was used to honing the workpiece, the variation in the surface roughness of the inner wall of the machined hole in the workpiece per machining cycle was smaller than the variation in the surface roughness of the inner wall of the machined hole in the workpiece per machining cycle when the grinding wheel according to Example 2 was used to honing the workpiece. In other words, it was found that by reducing the protrusion amount of the abrasive grains on part of the grinding surface as with the grinding wheels according to Examples 2 and 3, the so-called surface roughness of the inner wall of the machined hole in the workpiece when the grinding wheel was used to honing the workpiece was improved compared to when the protrusion amount of the abrasive grains on the entire grinding surface was increased as with the grinding wheel according to Example 1.

[0019] In this way, by forming areas with different amounts of abrasive grain protrusion within the grinding surface of the grinding wheel, it is possible to fine-tune the surface roughness of the inner wall of the workpiece's machining hole when the workpiece is honed using the grinding wheel, or the torque required to rotate the honing tool to which the grinding wheel is fixed at its tip.

[0020] The surface roughness of the inner wall of the machining hole in the workpiece when honing the workpiece was compared using the grinding wheel of Example 4, in which the protruding amount of the abrasive grains was uniform across the entire grinding surface Gf of the grinding wheel G, and the grinding wheels of Examples 5 and 6, which had the grinding surface Gf shown in FIG. 5(B). The grinding wheel of Example 4 was dressed so that the average protruding amount of the abrasive grains across the entire grinding surface Gf was the same as the average protruding amount of the abrasive grains in the first region Gf1 of the grinding surface Gf of the grinding wheels of Examples 5 and 6. The grinding wheel of Example 5 was dressed so that the ratio of the first region Gf1 to the entire grinding surface was 45%, and the grinding wheel of Example 6 was dressed so that the ratio of the first region Gf1 to the entire grinding surface was 62%. As shown in FIG. 7 , when the workpiece was honed using the grindstones according to Examples 5 and 6, the surface roughness of the inner wall of the machined hole in the workpiece was smaller than the surface roughness of the inner wall of the machined hole in the workpiece when the workpiece was honed using the grindstone according to Example 4. Furthermore, when the workpiece was honed using the grindstone according to Example 5, the surface roughness of the inner wall of the machined hole in the workpiece was smaller than the surface roughness of the inner wall of the machined hole in the workpiece when the workpiece was honed using the grindstone according to Example 6. In the honing process using the grindstones according to Examples 5 and 6, when the grindstone G slides against the workpiece W as shown by the arrows in FIGS. 8(A) and 8(B), the second region Gf2 of the grinding surface Gf, where the protrusion amount of the abrasive grains AB is relatively small, sweeps the machined surface of the workpiece W, which has been ground using the first region Gf1 of the grinding surface Gf. This is thought to reduce the surface roughness of the machined surface of the workpiece W. Furthermore, since the area of ​​the second region Gf2 of the grinding wheel G according to Example 5 shown in Fig. 8(A) is larger than the area of ​​the second region Gf2 of the grinding wheel G according to Example 6 shown in Fig. 8(B), the machined surface of the portion surrounded by the dashed line in Fig. 8(A) has a smaller surface roughness than the machined surface of the portion surrounded by the dashed line in Fig. 8(B). In other words, by changing the area ratio between the first region Gf1 and the second region Gf2 on the grinding surface Gf of the grinding wheel G, the properties of the machined surface of the workpiece W can be controlled.

[0021] As described above, according to the dressing method of this embodiment, the intensity of the laser light is changed while moving the irradiation area of ​​the laser light on the grinding surface Gf of the grinding wheel G, thereby forming a plurality of areas with different protruding amounts of abrasive grains on the grinding surface of the grinding wheel G. This allows the grinding performance of the grinding wheel G to be changed by changing the area ratio of each of the plurality of areas on the grinding surface Gf of the grinding wheel G, and therefore the grinding performance of the grinding wheel G can be finely adjusted.

[0022] Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations of the above-described embodiments. For example, a plurality of first regions Gf1 may be formed within the grinding surface Gf of the grinding wheel G so as to extend along the longitudinal direction of the grinding surface Gf.

[0023] In the embodiment, an example has been described in which the dressing device includes the head attitude changer 13 that changes the radiation direction of the laser beam LA1 by changing the attitude of the laser head 12. However, the present invention is not limited to this. The dressing device may also include a head transport unit 2013 that moves the laser head 12 in a direction parallel to the grinding surface Gf of the grinding wheel G held by the grinding wheel holder 11, as indicated by an arrow AR2001 in Fig. 9, thereby moving an irradiation area on the grinding surface Gf of the grinding wheel G that is irradiated with the laser beam LA1. The head transport unit 2013 includes a first transport unit 2131 that transports the laser head 12 along a first direction parallel to the grinding surface Gf, and a second transport unit 2132 that transports the laser head 12 and the first transport unit 2131 along a second direction that is parallel to the grinding surface Gf and perpendicular to the first direction.

[0024] In the embodiment, an example has been described in which the laser head 12 focuses the laser beam LA1 onto the grinding surface Gf so that the area of ​​the irradiation region on the grinding surface Gf is at least smaller than the area of ​​the grinding surface Gf. However, this is not limiting. For example, the laser head 12 may focus the laser beam LA1 so that the area of ​​the irradiation region is substantially the same as the area of ​​the entire grinding surface Gf. The amount of protrusion of the abrasive grains on the entire grinding surface Gf may be adjusted by adjusting the manner in which the intensity of the laser beam LA1 is changed. Specifically, the laser head 12 may adjust the amount of protrusion of the abrasive grains by appropriately changing the cycle in which the entire grinding surface Gf is irradiated with the laser beam LA1 at maximum intensity and at approximately half the maximum intensity, and the ratio between the irradiation time at maximum intensity and the irradiation time at approximately half the maximum intensity within one cycle.

[0025] Although the embodiments and modifications of the present invention have been described above, the present invention is not limited to these. The present invention includes any combination of the embodiments and modifications, and any combination to which appropriate modifications have been made. [Industrial Applicability]

[0026] The present invention is suitable as a method for dressing a grindstone fixed to the tip of a honing tool. [Explanation of symbols]

[0027] 11: grinding wheel holding unit, 12: laser head, 13: head position changing unit, 21: control unit, 22: terminal device, 2013: head transport unit, 2131: first transport unit, 2132: second transport unit, AB: abrasive grain, G, G1, G2: grinding wheel, Gf: grinding surface, Gf1: first area, Gf2: second area, LA1: laser light, W: workpiece

Claims

1. A dressing method for adjusting the protrusion amount of the abrasive grains by holding a grinding wheel, which is made of abrasive grains bonded with a binder, with a grinding surface of the grinding wheel exposed, and irradiating the grinding surface with a laser beam to melt and evaporate the binder, comprising: adjusting the protrusion amount on the grinding surface by changing the intensity of the laser light; Dressing method.

2. a laser beam is condensed and irradiated onto the grinding surface so that an area of ​​an irradiation region on the grinding surface where the laser beam is irradiated is at least smaller than an area of ​​the grinding surface, and the intensity of the laser beam is changed while the irradiation region on the grinding surface is moved; The dressing method according to claim 1 .

3. and changing the intensity of the laser light while moving the irradiation area on the grinding surface, thereby forming a plurality of areas on the grinding surface with different average values ​​of the protrusion amount. The dressing method according to claim 2 .

4. The grinding wheel has a long grinding surface in a plan view, and is attached to the tip of a long honing tool that hones the inner surface of a machining hole in a workpiece so that the longitudinal direction of the grinding surface is along the longitudinal direction of the honing tool. With the grinding surface in contact with the inner surface of the machining hole, the honing tool is rotated around a central axis along the longitudinal direction of the honing tool, whereby the grinding wheel slides in the short direction of the grinding surface to grind the inner surface of the machining hole. the plurality of regions are composed of a first region extending in a direction intersecting a short-side direction of the grinding surface and a second region other than the first region on the grinding surface, an average value of the protrusion amount in the first region is greater than an average value of the protrusion amount in the second region; The dressing method according to claim 3 .

5. The grinding wheel has a long grinding surface in a plan view, and is attached to the tip of a long honing tool that hones the inner surface of a machining hole in a workpiece so that the longitudinal direction of the grinding surface is along the longitudinal direction of the honing tool. With the grinding surface in contact with the inner surface of the machining hole, the honing tool is rotated around a central axis along the longitudinal direction of the honing tool, whereby the grinding wheel slides in the short direction of the grinding surface to grind the inner surface of the machining hole. the plurality of regions are composed of a first region that includes one end of the grinding surface in the short direction and extends over the entire longitudinal direction of the grinding surface, and a second region on the grinding surface other than the first region, an average value of the protrusion amount in the first region is greater than an average value of the protrusion amount in the second region; The dressing method according to claim 3 .

6. a grinding wheel holder that holds a grinding wheel made of abrasive grains bonded together with a binder, with the grinding surface of the grinding wheel exposed; a laser head that condenses a laser beam so that an area of ​​an irradiation region on the grinding surface where the laser beam is irradiated is smaller than an area of ​​the grinding surface; and a head attitude changing unit that changes the attitude of the laser head to change the radiation direction of the laser light, thereby moving the irradiation area on the grinding surface; a control unit that controls the head attitude changing unit to move the irradiation area on the grinding surface, and controls the laser head to change the intensity of the laser light, thereby adjusting the protrusion amount of the abrasive grains on the grinding surface. Dressing device.

7. A grindstone is made of abrasive grains bonded together with a binder, has a long grinding surface in a plan view, and is attached to a tip of a long honing tool that hones the inner surface of a machining hole in a workpiece so that the longitudinal direction of the grinding surface is along the longitudinal direction of the honing tool, and the honing tool is rotated around a central axis along the longitudinal direction of the honing tool with the grinding surface in contact with the inner surface of the machining hole, thereby sliding in the short direction of the grinding surface to grind the inner surface of the machining hole, an average value of the protrusion amount of the abrasive grains in a first region extending in a direction intersecting with the short side direction of the grinding surface is larger than an average value of the protrusion amount in a second region other than the first region on the grinding surface; Whetstone.

8. A grindstone is made of abrasive grains bonded together with a binder, has a long grinding surface in a plan view, and is attached to a tip of a long honing tool that hones the inner surface of a machining hole in a workpiece so that the longitudinal direction of the grinding surface is along the longitudinal direction of the honing tool, and the honing tool is rotated around a central axis along the longitudinal direction of the honing tool with the grinding surface in contact with the inner surface of the machining hole, thereby sliding in the short direction of the grinding surface to grind the inner surface of the machining hole, an average value of the protrusion amounts of the abrasive grains in a first region that includes an entire one end in the short direction of the grinding surface and extends over the entire longitudinal direction of the grinding surface is larger than an average value of the protrusion amounts in a second region other than the first region on the grinding surface; Whetstone.

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