JP2021151673A - Super finishing whetstone and grinding device - Google Patents

Abstract

To provide a super finishing whetstone that can reduce an increase in tensile stress caused by an increase in contact area between a whetstone and a machining target member associated with the progress of machining as well as breakage or deficiency of the whetstone associated with the increase in tensile stress.SOLUTION: A super finishing whetstone according to one embodiment includes a whetstone holding layer, a stress relaxation layer, and a whetstone layer sandwiched between the whetstone holding layer and the stress relaxation layer. The whetstone holding layer has a Young's modulus smaller than a Young's modulus of the whetstone layer.SELECTED DRAWING: Figure 2

Description

The present invention relates to a super-finishing grindstone and a polishing apparatus.

As the grindstone used for the super-finishing process, a grindstone having a uniform structure over the entire surface formed by mixing the abrasive grains and the binder is usually used.

Conventionally, as a grindstone having a structure having a plurality of layers, a processing grindstone described in Patent Document 1 (Japanese Unexamined Patent Publication No. 60-006357) is known. The processing grindstone described in Patent Document 1 is composed of abrasive grains and a binder. The processing grindstone of Patent Document 1 contains pores inside.

The processing grindstone described in Patent Document 1 has a first layer and a second layer. The first layer is arranged at a position closer to the surface than the second layer in the thickness direction of the processing grindstone. The pores contained in the first layer are filled with the first filler. The pores contained in the second layer are filled with the second filler. The first filler is a filler composed of a material different from that of the second filler. The first filler has a higher hardness than the second filler. As a result, the strength of the first layer becomes higher than the strength of the second layer, and the strength of the treated grindstone is improved.

Japanese Unexamined Patent Publication No. 60-006357

In superfinishing, the contact area between the grindstone and the member to be machined increases as the machining progresses, so that the tensile stress applied to the superfinishing grindstone increases. Such an increase in tensile stress causes the super-finishing grindstone to be chipped or broken. Although the treated grindstone described in Patent Document 1 has been improved in strength, it does not take into consideration the breakage and breakage due to the increase in tensile stress over time with the progress of processing.

The present invention has been made in view of the above-mentioned problems of the prior art. More specifically, the present invention provides a super-finishing grindstone and a grinding device capable of suppressing breakage and chipping of the grindstone as the processing progresses.

The super-finishing grindstone according to one aspect of the present invention includes a grindstone holding layer, a stress relaxation layer, and a grindstone layer sandwiched between the grindstone holding layer and the stress relaxation layer. The Young's modulus of the grindstone holding layer is smaller than the Young's modulus of the grindstone layer. According to the super-finishing grindstone according to one aspect of the present invention, since the grindstone layer is reinforced by the grindstone holding layer and the stress relaxation layer, it is possible to suppress breakage and chipping of the grindstone as the processing progresses.

Further, since the Young's modulus of the grindstone holding layer is smaller than the Young's modulus of the grindstone layer, the grindstone holding layer is easily deformed and adheres to the surface of the machining target member when it is urged by the machining target member. As a result, it is possible to prevent chips adhering to the surface of the member to be processed from entering the vicinity of the processed portion when they return to the vicinity of the processed portion as the member to be processed rotates.

In the above-mentioned super-finishing grindstone, the wear resistance of the stress relaxation layer may be lower than the wear resistance of the grindstone layer. In this case, as the processing progresses, it is more easily worn than the grindstone layer, and the contact area between the grindstone and the member to be processed is less likely to increase and the tensile stress due to the increase is less likely to occur. Can be further suppressed.

When the grindstone holding layer is made of a flexible material such as a resin material, the grindstone holding layer is more likely to adhere to the surface of the member to be processed. As a result, it is possible to further prevent chips adhering to the surface of the member to be processed from entering the vicinity of the processed portion when returning to the vicinity of the processed portion due to the rotation of the member to be processed.

In the above-mentioned super-finishing grindstone, the stress relaxation layer may contain first abrasive grains having a first hardness. The grindstone layer may contain second abrasive grains having a second hardness equal to or higher than the first hardness. In this case, since the stress relaxation layer is more easily worn than the grindstone layer, the tensile stress increases due to the increase in the contact area between the grindstone and the member to be machined as the machining progresses, and the grindstone is further broken or damaged. It can be suppressed.

In the above-mentioned super-finishing grindstone, the content of abrasive grains in the stress relaxation layer may be smaller than the content of abrasive grains in the grindstone layer. In this case, since the stress relaxation layer is more easily worn than the grindstone layer, the tensile stress increases due to the increase in the contact area between the grindstone and the member to be machined as the machining progresses, and the grindstone breaks or breaks due to the increase. Can be further suppressed.

In the above-mentioned super-finishing grindstone, the grindstone holding layer may have a first thickness. The stress relaxation layer may have a second thickness. The grindstone layer may have a third thickness. The ratio of the third thickness to the total of the first thickness, the second thickness, and the third thickness may be 40% or more and 60% or less.

When the grindstone layer becomes thin, the grindstone layer is likely to be damaged or broken. However, in the above-mentioned super-finishing grindstone, due to the presence of the grindstone holding layer and the stress relaxation layer, even if the grindstone layer becomes relatively thin, the tensile stress due to the increase in the contact area between the grindstone and the member to be machined as the machining progresses. It is possible to suppress the increase and the breakage and breakage of the grindstone due to it. When the grindstone layer becomes relatively thin, even if the pressing force on the grindstone by the cylinder is reduced, the surface pressure in the grindstone layer during processing can be secured, so that the cylinder or the like can be miniaturized. The miniaturization of the cylinder leads to a reduction in the consumption of air that drives the cylinder. Further, since the miniaturization of the cylinder leads to a reduction in the moment of inertia of the swing head that holds the grindstone, it is possible to suppress the occurrence of excessive swing of the swing head.

The grinding apparatus according to one aspect of the present invention includes the above-mentioned super-finishing grindstone and a swing head that holds the super-finishing grindstone so as to urge the outer peripheral surface of a ring-shaped machining target member that rotates around a central axis. Be prepared. The swing head holds the superfinished grindstone so that the grindstone layer contacts the outer peripheral surface after the grindstone holding layer contacts the outer peripheral surface, and the stress relaxation layer contacts the outer peripheral surface after the grindstone layer contacts the outer peripheral surface. do.

In the grinding apparatus according to one aspect of the present invention, the grindstone holding layer comes into contact with the outer peripheral surface of the member to be machined before the grindstone layer. Therefore, the chips adhering to the surface of the member to be processed are blocked by the grindstone holding layer before entering between the grindstone layer and the outer peripheral surface of the member to be processed. Therefore, in this case, it is possible to further prevent chips adhering to the surface of the member to be processed from entering the vicinity of the processed portion.

It is possible to suppress an increase in tensile stress due to an increase in the contact area between the grindstone and the member to be machined as the machining progresses, and the resulting breakage and breakage of the grindstone.

It is a top view of the super finishing grindstone 10 which concerns on embodiment. It is sectional drawing in II-II of FIG. It is a front view of the grinding apparatus 100 which concerns on embodiment. It is a top view of the member to be processed. It is sectional drawing in VV of FIG.

Details of the embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and duplicate explanations will not be repeated.

(Structure of super-finishing grindstone according to the embodiment)
The configuration of the super-finishing grindstone 10 according to the embodiment will be described below.

FIG. 1 is a top view of the super finishing grindstone 10 according to the embodiment. FIG. 2 is a cross-sectional view taken along the line II-II of FIG. As shown in FIGS. 1 and 2, the super-finishing grindstone 10 has a columnar shape. The longitudinal direction of the super-finishing grindstone 10 is shown in FIG. 1 as the first direction DR1.

The super-finishing grindstone 10 has a top surface 10a and a bottom surface 10b. The bottom surface 10b is the opposite surface of the top surface 10a. The super-finishing grindstone 10 has a first side surface 10c and a second side surface 10d. The first side surface 10c and the second side surface 10d face each other in a direction orthogonal to the first direction DR1. In the following, the direction orthogonal to the first direction DR1 is referred to as the second direction DR2. The second direction DR2 is the width direction of the super finishing grindstone 10.

The super-finishing grindstone 10 has a third side surface 10e and a fourth side surface 10f. The third side surface 10e is arranged at one end of the super finishing grindstone 10 in the first direction DR1. The third side surface 10e is preferably formed of a cylindrical surface. The fourth side surface 10f is arranged at the other end of the super finishing grindstone 10 in the first direction DR1.

As shown in FIG. 2, the superfinishing grindstone 10 has a grindstone holding layer 11, a stress relaxation layer 12, and a grindstone layer 13. The grindstone layer 13 is sandwiched between the grindstone holding layer 11 and the stress relaxation layer 12. The grindstone holding layer 11 is arranged on the upper surface 10a, and the stress relaxation layer 12 is arranged on the bottom surface 10b.

The grindstone holding layer 11 has a first thickness T1. The first thickness T1 is the thickness of the grindstone holding layer 11 in the third direction DR3 orthogonal to the first direction DR1 and the second direction DR2. The stress relaxation layer 12 has a second thickness T2. The second thickness T2 is the thickness of the stress relaxation layer 12 in the third direction DR3. The grindstone layer 13 has a third thickness T3. The third thickness T3 is the thickness of the grindstone layer 13 in the third direction.

The ratio of the third thickness T3 to the total of the first thickness T1, the second thickness T2, and the third thickness T3 is preferably 40% or more and 60% or less. That is, the value obtained by dividing the third thickness T3 by the total of the first thickness T1, the second thickness T2, and the third thickness T3 is preferably 0.4 or more and 0.6 or less.

The Young's modulus of the grindstone holding layer 11 is smaller than the Young's modulus of the grindstone layer 13. From another point of view, the stress relaxation layer 12 is relatively more easily deformed than the grindstone layer 13. The strength of the grindstone holding layer 11 is preferably higher than the strength of the grindstone layer 13. The magnitude relationship between the strength of the grindstone holding layer 11 and the strength of the grindstone layer 13 can be measured by a three-point bending tester.

The grindstone holding layer 11 is preferably made of a material that is more flexible than the grindstone layer 13. The grindstone holding layer 11 is preferably made of a resin material. The grindstone holding layer 11 is made of, for example, a synthetic resin material. The resin material used for the grindstone holding layer 11 is, for example, a thermosetting resin or a thermoplastic resin. The resin material used for the grindstone holding layer 11 is preferably a phenol resin.

The wear resistance of the stress relaxation layer 12 is preferably equal to or less than the wear resistance of the grindstone layer 13. Regarding the magnitude relationship between the wear resistance of the stress relaxation layer 12 and the wear resistance of the grindstone layer 13, the stress relaxation layer 12 and the grindstone layer 13 are polished using a material having a certain roughness, and the amount of wear at that time is evaluated. It can be determined by doing.

The stress relaxation layer 12 may contain the first abrasive grains. The grindstone layer 13 may have a second abrasive grain. The grindstone layer 13 contains a binder in addition to the above-mentioned second abrasive grains. The hardness of the first abrasive grains is the first hardness. The hardness of the second abrasive grains is the second hardness. The second hardness is preferably equal to or higher than the first hardness. The first hardness and the second hardness can be measured by, for example, a Knoop hardness tester. The first hardness and the second hardness may be measured by a Vickers hardness tester.

The second abrasive grains are abrasive grains composed of, for example, white aluminum oxide, aluminum oxide, silicon carbide, green silicon carbide, CBN (Cubic Boron Nitride), diamond, and the like.

The stress relaxation layer 12 does not have to contain abrasive grains. That is, the stress relaxation layer 12 may be composed of only a binder. The stress relaxation layer 12 may be made of, for example, rubber, a resin material, or the like.

The content of abrasive grains in the stress relaxation layer 12 is preferably smaller than the content of abrasive grains in the grindstone layer 13. The content of abrasive grains in the stress relaxation layer 12 (content of the grindstone in the grindstone layer 13) is calculated by image processing as the area ratio of the grindstone contained in the stress relaxation layer 12 (grindstone layer 13) in a cross-sectional view. Measured by In "the content of abrasive grains in the stress relaxation layer 12 is smaller than the content of abrasive grains in the grindstone layer 13", the abrasive grains are not contained in the stress relaxation layer 12, and the grindstone layer 13 does not contain abrasive grains. It also includes the case where abrasive grains are contained therein.

(Manufacturing method of super-finishing whetstone 10 according to the embodiment)
In the production of the super-finishing grindstone 10 according to the embodiment, first, the grindstone holding layer 11, the stress relaxation layer 12, and the grindstone layer 13 are separately manufactured. Second, the grindstone holding layer 11, the stress relaxation layer 12, and the grindstone layer 13 are each finished to a predetermined size and are bonded to each other. When the stress relaxation layer 12 and the grindstone layer 13 are made of bonds made of the same material, these two layers may be formed at the same time, finished to a predetermined size, and adhered to the grindstone holding layer 11. Further, when the grindstone holding layer 11, the stress relaxation layer 12, and the grindstone layer 13 are made of the same type of bond, these three layers can be formed at the same time. Third, the bonded grindstone holding layer 11, stress relaxation layer 12, and grindstone layer 13 are cut and finished according to the required dimensions.

(Structure of Grinding Device 100 According to Embodiment)
The configuration of the grinding apparatus 100 according to the embodiment will be described below.

FIG. 3 is a front view of the grinding device 100 according to the embodiment. As shown in FIG. 3, the grinding device 100 includes a super-finishing grindstone 10, a swing head 20, a backing plate 30, and a clamp roll 40.

The swing head 20 has a main body portion 21 and a grindstone holding portion 22. Although not shown in FIG. 3, the swing head 20 has a cylinder. The main body 21 is configured to be rotatable around the central axis 21a. The grindstone holding portion 22 extends from the outer periphery of the main body portion 21 along the direction of the central axis 21a. The super-finishing grindstone 10 is held at the tip of the grindstone holding portion 22.

The cylinder urges the super-finishing grindstone 10 toward the outer peripheral surface of the member to be machined (the outer peripheral surface 50d of the inner ring 50 described later). The super-finishing grindstone 10 held by the grindstone holding portion 22 swings in a plane orthogonal to the central shaft 21a by rotating the main body portion 21 around the central shaft 21a.

FIG. 4 is a top view of the member to be processed. FIG. 5 is a cross-sectional view taken along the line VV of FIG. As shown in FIGS. 4 and 5, the member to be processed is a ring-shaped member. For example, the member to be machined is the inner ring 50 of the deep groove ball bearing. In the following, the inner ring 50 will be described as an example of the member to be machined. The inner ring 50 has an upper surface 50a, a lower surface 50b, an inner peripheral surface 50c, an outer peripheral surface 50d, and a central axis 50e.

The upper surface 50a and the bottom surface 50b form end faces in the direction of the central axis 50e. The bottom surface 50b is the opposite surface of the top surface 50a. The inner peripheral surface 50c and the outer peripheral surface 50d are connected to the upper surface 50a and the lower surface 50b. The inner peripheral surface 50c is closer to the central axis 50e than the outer peripheral surface 50d. A track groove is formed on the outer peripheral surface 50d.

The inner ring 50 is fixed by being sandwiched between the backing plate 30 and the clamp roll 40. The backing plate 30 is configured to rotate the inner ring 50 around the central axis 50e.

The super-finishing grindstone 10 is held by the grindstone holding portion 22 so that the upper surface 10a faces upward in the drawing. The inner ring 50 preferably rotates counterclockwise in the drawing. That is, it is preferable that the super-finishing grindstone 10 is held by the swing head 20 (grindstone holding portion 22) so that the upper surface 10a side comes into contact with the outer peripheral surface 50d of the inner ring 50 before the bottom surface 10b side. From another point of view, in the super-finishing grindstone 10, the grindstone holding layer 11 first contacts the outer peripheral surface 50d of the inner ring 50, and the grindstone layer 13 contacts the outer peripheral surface 50d of the inner ring 50. Thirdly, it is preferable that the stress relaxation layer 12 is held by the swing head 20 (grinding stone holding portion 22) so as to come into contact with the outer peripheral surface 50d of the inner ring 50.

(Effects of the super-finishing grindstone 10 and the grinding device 100 according to the embodiment)
The effect of the super-finishing grindstone 10 according to the embodiment will be described below.

In the super-finishing grindstone 10, since the grindstone layer 13 is reinforced by the grindstone holding layer 11 and the stress relaxation layer 12, it is possible to suppress breakage and breakage of the grindstone.

In the super-finishing grindstone 10, when the grindstone holding layer 11 has a Young's modulus smaller than that of the grindstone layer 13, when the super-finishing grindstone 10 is urged to the member to be machined, the grindstone holding layer 11 is deformed and is to be machined. Easy to adhere to the surface of the member. As a result, the super-finishing grindstone 10 can suppress the chips adhering to the surface of the member to be machined from entering the vicinity of the machined portion when they return to the vicinity of the machined portion due to the rotation of the member to be machined. ..

When the grindstone holding layer 11 has a higher strength than the grindstone layer 13, the grindstone layer 13 is further reinforced by the grindstone holding layer 11. When the wear resistance of the stress relaxation layer 12 is lower than that of the grindstone layer 13, the stress relaxation layer 12 is likely to be worn away during the superfinishing process, so that the process is accompanied by the progress of the superfinishing process. The increase in contact area with the target member and the increase in tensile stress based on it are less likely to occur. Therefore, in this case, breakage and breakage of the grindstone can be further suppressed.

In the super-finishing grindstone 10, the stress relaxation layer 12 is discharged while entraining chips generated from the machining target member when it is machined by contact with the machining target member. Therefore, according to the super-finishing grindstone 10. , The removal of chips can be promoted.

In the super-finishing grindstone 10, when the grindstone holding layer 11 is made of a flexible material such as a resin material, the grindstone holding layer 11 is more likely to adhere to the surface of the member to be processed. Therefore, in this case, it is possible to further prevent the chips adhering to the surface of the member to be processed from entering the vicinity of the processed portion when they return to the vicinity of the processed portion due to the rotation of the member to be processed.

In the super-finishing grindstone 10, when the stress relaxation layer 12 contains the first abrasive grains having the first hardness and the grindstone layer 13 contains the second abrasive grains having the second hardness equal to or higher than the first hardness, the stress Since the relaxation layer 12 is more easily worn than the grindstone layer 13, the increase in tensile stress due to the increase in the contact area between the grindstone and the member to be machined as the machining progresses, and the accompanying breakage and breakage of the grindstone are suppressed. Can be done.

In the super-finishing grindstone 10, the content of abrasive grains in the stress relaxation layer 12 may be smaller than the content of abrasive grains in the grindstone layer 13. In this case, since the stress relaxation layer 12 is more easily worn than the grindstone layer 13, the tensile stress increases due to the increase in the contact area between the grindstone and the member to be machined as the machining progresses, and the grindstone is broken due to the increase. , The defect can be suppressed.

In the super-finishing grindstone 10, when the ratio of the third thickness T3 to the total of the first thickness T1, the second thickness T2 and the third thickness T3 is 40% or more and 60% or less, the processing proceeds. It is possible to reduce the size of the cylinder while suppressing an increase in tensile stress due to an increase in the contact area between the grindstone and the member to be machined and the accompanying breakage and breakage of the grindstone. By reducing the size of the cylinder, it is possible to reduce the amount of air consumed and the moment of inertia of the swing head.

The effect of the grinding apparatus 100 according to the embodiment will be described below.

In the grinding device 100, the grindstone holding layer 11 comes into contact with the outer peripheral surface of the member to be machined before the grindstone layer 13. Therefore, the chips adhering to the surface of the member to be processed are blocked by the grindstone holding layer 11 before entering between the grindstone layer 13 and the outer peripheral surface of the member to be processed. Therefore, according to the grinding apparatus 100, it is possible to further prevent chips adhering to the surface of the member to be processed from entering the vicinity of the processed portion.

Although the embodiment of the present invention has been described above, it is possible to modify the above-described embodiment in various ways. Moreover, the scope of the present invention is not limited to the above-described embodiment. The scope of the present invention is indicated by the scope of claims and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

The above embodiment is particularly advantageously applied to a superfinishing grindstone and a grinding machine using the superfinishing grindstone.

10 Super-finishing grindstone, 10a top surface, 10b bottom surface, 10c first side surface, 10d second side surface, 10e third side surface, 10f fourth side surface, 11 grindstone holding layer, 12 stress relaxation layer, 13 grindstone layer, 20 swing head, 21 Main body, 21a Central shaft, 22 Grindstone holder, 30 Backing plate, 40 Clamp roll, 50 Inner ring, 50a Top surface, 50b Bottom surface, 50c Inner peripheral surface, 50d Outer surface surface, 50e Central axis, 100 Grinding device, DR1 1st Direction, DR2 second direction, DR3 third direction, T1 first thickness, T2 second thickness, T3 third thickness.

Claims (7)

With the grindstone holding layer,
Stress relaxation layer and
A grindstone layer sandwiched between the grindstone holding layer and the stress relaxation layer is provided.
A super-finishing grindstone in which the Young's modulus of the grindstone holding layer is smaller than the Young's modulus of the grindstone layer. The super-finishing grindstone according to claim 1, wherein the wear resistance of the stress relaxation layer is equal to or less than the wear resistance of the grindstone layer. The super-finishing grindstone according to claim 1 or 2, wherein the grindstone holding layer is made of a resin material. The stress relaxation layer contains the first abrasive grains having the first hardness, and contains the first abrasive grains.
The super-finishing grindstone according to any one of claims 1 to 3, wherein the grindstone layer contains a second grindstone having a second hardness equal to or higher than the first hardness. The super-finishing grindstone according to any one of claims 1 to 4, wherein the content of abrasive grains in the stress relaxation layer is smaller than the content of abrasive grains in the grindstone layer. The grindstone holding layer has a first thickness and has a first thickness.
The stress relaxation layer has a second thickness and has a second thickness.
The grindstone layer has a third thickness and has a third thickness.
One of claims 1 to 5, wherein the ratio of the third thickness to the total of the first thickness, the second thickness, and the third thickness is 40% or more and 60% or less. Super-finishing whetstone described in. The super-finishing grindstone according to any one of claims 1 to 6.
A swing head that holds the super-finishing grindstone so as to urge the outer peripheral surface of the ring-shaped member to be machined that rotates around the central axis is provided.
In the swing head, after the grindstone holding layer comes into contact with the outer peripheral surface, the grindstone layer comes into contact with the outer peripheral surface, and after the grindstone layer comes into contact with the outer peripheral surface, the stress relaxation layer comes into contact with the outer peripheral surface. A grinding device that holds the superfinished grindstone so that it comes into contact with it.

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