Resin bond grinding wheel

Abstract

To provide a resin bond grinding wheel capable of improving a grinding wheel life and grinding performance by securing abrasive grain holding force.SOLUTION: A resin bond grinding wheel 1 includes a plurality of abrasive grains 2, holding force reinforcing layers 3, and bonding parts 4. The holding force reinforcing layer 3 is configured to include a first resin 30 and first fillers 5, covers surfaces of the abrasive grains 2, and holds the abrasive grains 2. The bonding part 4 has a composition different from that of the holding force reinforcing layer 3, is configured to include a second resin 40, and bonds the holding force reinforcing layers 3 covering the abrasive grains 2 to each other. The first filler 5 includes at least a holding force reinforcing filler 51 having an elastic modulus higher than that of the first resin 30. The bonding part 4 includes no holding force reinforcing fillers 51, or has a lower content of the holding force reinforcing fillers 51 per unit volume than that of the holding force reinforcing layer 3.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a resin bonded grinding wheel. [Background technology]

[0002] For example, a resin-bonded grinding wheel is known that includes abrasive grains and a resin layer that contains a thermosetting resin and metal powder, as disclosed in Patent Document 1. The resin-bonded grinding wheel described in Patent Document 1 is intended to prevent abrasive grains from falling off and improve grinding power by including a resin layer that contains metal powder. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5456535 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the resin-bonded grinding wheel described in Patent Document 1, the abrasive grains are bonded together by a resin layer containing metal powder. Therefore, when grinding a workpiece, the resin layer containing metal powder may not easily recede from the abrasive grains, and the grinding resistance may be large. Therefore, from the viewpoint of grinding performance, there is room for improvement.

[0005] The present invention has been made in consideration of the above background, and aims to provide a resin-bonded grinding wheel that can improve the wheel life and grinding performance by ensuring abrasive grain retention. [Means for solving the problem]

[0006] One aspect of the present invention is a method for manufacturing a grinding machine comprising: a retention reinforcing layer that includes a first resin and a first filler, covers the surfaces of the abrasive grains, and holds the abrasive grains; a bonding portion that has a composition different from that of the retention reinforcing layer, contains a second resin, and bonds the retention reinforcing layers that cover the abrasive grains together; Equipped with The first filler includes at least a retention-enhancing filler having a higher elastic modulus than the first resin, The bonded portion is in a resin-bonded grinding wheel that does not contain the retention enhancing filler or that has a lower content of the retention enhancing filler per unit volume than the retention enhancing layer. Effect of the Invention

[0007] In the resin-bonded grinding wheel, the surface of the abrasive grains is covered with a retention-reinforcing layer containing a retention-reinforcing filler. Therefore, the resin-bonded grinding wheel can exert a high retention force of the abrasive grains due to the retention-reinforcing layer, and it is easy to suppress the abrasive grains from falling off. Therefore, it is easy to improve the grinding wheel life and ensure grinding performance. In addition, the bonded part does not contain a retention-reinforcing filler, or has a smaller content of retention-reinforcing filler per unit volume than the retention-reinforcing layer. Therefore, when grinding a workpiece, the bonded part is easy to retreat from the abrasive grains, and it is easy to reduce the grinding resistance. As a result, it is possible to improve the grinding performance.

[0008] As described above, according to the above-described embodiment, it is possible to provide a resin-bonded grinding wheel that can improve the grinding performance by ensuring abrasive grain retention and thereby improving the wheel life. [Brief description of the drawings]

[0009] [Figure 1] FIG. 3 is an external view of a grinding wheel equipped with a resin-bonded grinding stone in the first embodiment, taken along the line I in FIG. 2. [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 2 is an enlarged cross-sectional view of a resin bonded grinding wheel according to the first embodiment. [Figure 4] 4 is an enlarged cross-sectional view of the vicinity of an abrasive grain held by a retention reinforcing layer in the first embodiment. FIG. [Diagram 5]3 is a flowchart showing a method for manufacturing a resin bonded grinding wheel in the first embodiment. [Figure 6] 3 is a graph showing bending strengths of Example 1 and Comparative Example 1 in Experimental Example 1. [Figure 7] FIG. 2 is an enlarged cross-sectional view of a resin-bonded grinding wheel in Comparative Example 1. [Figure 8] 13 is a graph showing the relationship between the grinding ratio and the current value in Example 1 and Comparative Example 1 in Experimental Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (Embodiment 1) 1.Applicable objects of resin bond grinding wheels The resin-bonded grinding wheel is applied to, for example, a grinding wheel used for grinding a hard and brittle workpiece. The workpiece to be ground can be, for example, a ceramic made of silicon carbide, alumina, or the like.

[0011] 2. Configuration of Grinding Wheel 10 A grinding wheel 10 to which a resin-bonded grinding wheel 1 is applied will be described with reference to FIG. 1 and FIG. 2. As shown in FIG. 1 and FIG. 2, the grinding wheel 10 includes a base metal 101 and a resin-bonded grinding wheel 1 provided on the outer peripheral surface of the base metal 101. In this embodiment, the resin-bonded grinding wheel 1 is provided on the entire outer peripheral surface of the base metal 101. The base metal 101 is formed in a disk shape using a metal material such as steel, titanium alloy, or aluminum alloy. The base metal 101 has a shaft hole 102 that is fitted onto a rotating shaft of a grinding device (not shown). The grinding wheel 10 is rotated around the rotating shaft of the grinding device, and the resin-bonded grinding wheel 1 provided on the outer peripheral surface of the grinding wheel 10 is brought into sliding contact with the workpiece, thereby grinding the workpiece. The grinding surface of the workpiece can have various shapes such as a cylindrical surface, a flat surface, or a cam surface.

[0012] 3. Overview of the composition of resin bond grinding wheels 1 The outline of the configuration of the resin bonded grinding wheel 1 will be described with reference to Figs. 3 and 4. As shown in Fig. 3, the resin bonded grinding wheel 1 of this embodiment includes a plurality of abrasive grains 2, a retention-reinforcing layer 3, and a bonding portion 4. As shown in Fig. 4, the retention-reinforcing layer 3 is configured to include a first resin 30 and a first filler 5, covers the surface of the abrasive grains 2, and holds the abrasive grains 2. The bonding portion 4 has a different composition from the retention-reinforcing layer 3, is configured to include a second resin 40, and bonds the retention-reinforcing layers 3 covering the abrasive grains 2 together. The first filler 5 includes at least a retention-reinforcing filler 51 having a higher elastic modulus than the first resin 30. The bonding portion 4 does not include the retention-reinforcing filler 51, or has a smaller content of the retention-reinforcing filler 51 per unit volume than the retention-reinforcing layer 3. In other words, the bonding portion 4 does not contain a retention-strengthening filler 51, or even if it contains a retention-strengthening filler 51, the volume ratio of the retention-strengthening filler 51 contained in the bonding portion 4 to the entire bonding portion 4 is smaller than the volume ratio of the retention-strengthening filler 51 contained in the retention-strengthening layer 3 to the entire retention-strengthening layer 3.

[0013] 4. Detailed configuration of resin bond grinding wheel 1 The detailed configuration of the resin bonded grinding wheel 1 will be described with reference to Figs. 3 and 4. For example, diamond grains or CBN (cubic boron nitride) grains can be used as the abrasive grains 2 constituting the resin bonded grinding wheel 1. When the grinding target is a workpiece made of ceramics, diamond grains are suitable for the abrasive grains 2. In this embodiment, the abrasive grains 2 are diamond grains. The median diameter of the abrasive grains 2 is 25 to 400 µm.

[0014] To ensure the desired grinding performance for hard ceramics, it is preferable that the abrasive grains 2 are spaced apart from one another. Therefore, the volume ratio of the abrasive grains 2 to the entire resin bonded grinding wheel 1 (hereinafter simply referred to as the "abrasive grain ratio") is 35 volume % or less. The abrasive grain ratio is preferably 25 volume % or less, and more preferably 20 volume % or less. Moreover, the abrasive grain ratio is 6 volume % or more.

[0015] 3, the distance D1 between the abrasive grains 2 is 6 to 54 μm. The distance D1 is preferably 20 to 40 μm.

[0016] The abrasive grains 2 are held at the bonding portion 4 via a retention reinforcing layer 3. The retention reinforcing layer 3 covers 80% or more of the surface of the abrasive grains 2. It is preferable that the retention reinforcing layer 3 covers 95% or more of the surface of the abrasive grains 2. In this embodiment, the retention reinforcing layer 3 covers the entire surface of the abrasive grains 2. Furthermore, the retention reinforcing layer 3 is in close contact with the surface of the abrasive grains 2.

[0017] In this embodiment, the retention reinforcing layers 3 covering the abrasive grains 2 are not in contact with each other. However, a configuration in which parts of the outer peripheries of the retention reinforcing layers 3 covering adjacent abrasive grains 2 are in contact with each other may also be adopted. Also, a configuration in which one retention reinforcing layer 3 covers multiple abrasive grains 2 may also be adopted.

[0018] The thickness of the retention reinforcement layer 3 is smaller than the median diameter of the abrasive grains 2. The thickness of the retention reinforcement layer 3 is preferably 1 / 10 or less of the median diameter of the abrasive grains 2. Moreover, the thickness of the retention reinforcement layer 3 is 1 / 20 or more of the median diameter of the abrasive grains 2. The thickness of the retention reinforcement layer 3 is preferably 1 / 15 or more of the median diameter of the abrasive grains 2. The thickness of the retention reinforcement layer 3 is 3 to 27 μm. The thickness of the retention reinforcement layer 3 is preferably 4 to 20 μm.

[0019] The retention reinforcing layer 3 has a first filler 5. The first filler 5 has a retention reinforcing filler 51. In this embodiment, the first filler 5 is composed of only the retention reinforcing filler 51. The retention reinforcing layer 3 has a higher elastic modulus than the bonded portion 4. The Young's modulus value of the retention reinforcing layer 3 can be, for example, 1.5 times or more the Young's modulus value of the bonded portion 4. In addition, the ratio of the volume of the retention reinforcing filler 51 to the entire volume of the resin bonded grinding wheel 1 is 2 to 12 volume %. The shape of the first filler 5 can be, for example, spherical particles, fibrous particles, flake particles, or the like. In addition, the retention reinforcing layer 3 can also contain, for example, a thermally conductive filler for improving heat resistance as the first filler 5.

[0020] The retention-enhancing filler 51 is made of at least one of a metal and silicon carbide. In this embodiment, the retention-enhancing filler 51 has both a metal filler 511 made of a metal and a silicon carbide filler 512 made of silicon carbide, as shown in FIG. 4. As the metal filler 511, for example, a powder made of Co (cobalt) can be used. As the retention-enhancing filler 51, a filler made of, for example, carbon can be used in addition to a metal and silicon carbide.

[0021] The median diameter of the retention reinforcing filler 51 is 20% or less of the median diameter of the abrasive grains 2. The median diameter of the retention reinforcing filler 51 is preferably 10% or less of the median diameter of the abrasive grains 2. The median diameter of the retention reinforcing filler 51 is 2% or more of the median diameter of the abrasive grains 2. The median diameter of the retention reinforcing filler 51 is preferably 5% or more of the median diameter of the abrasive grains 2. The median diameter of the retention reinforcing filler 51 is 2.5 to 20.0 μm.

[0022] As shown in FIG. 4, the retention reinforcing layer 3 has a first resin 30. For example, a resin synthesized using phenol as a main raw material can be used as the first resin 30. In this embodiment, the first resin 30 is made of a novolac type phenolic resin. The first resin 30 covers the surfaces of the abrasive grains 2 and the first filler 5. The first resin 30 is covered from the outside by the second resin 40 of the bonding portion 4. The ratio of the volume of the first resin 30 to the volume of the entire resin bonded grinding wheel 1 is 5 to 30 volume %.

[0023] The bonding portion 4 bonds the respective retention reinforcing layers 3 together. In other words, the bonding portion 4 bonds the respective abrasive grains 2 covered with the retention reinforcing layers 3 together. The bonding portion 4 is configured to include a second resin 40 and a second filler 6, and the second filler 6 includes a different type of filler from the first filler 5. Note that the bonding portion 4 can also contain a retention reinforcing filler 51 as the second filler 6, so long as the bonding portion 4 has sufficient retractability with respect to the abrasive grains 2.

[0024] The second filler 6 contains at least one of a friable filler 61 having a lower hardness than the abrasive grains 2 and a thermally conductive filler 62 having a higher thermal conductivity than the second resin 40. In this embodiment, the second filler 6 has both the friable filler 61 and the thermally conductive filler 62. The ratio of the volume of the friable filler 61 to the entire volume of the resin bonded grindstone 1 can be, for example, 5 to 25 volume %. The ratio of the volume of the thermally conductive filler 62 to the entire volume of the resin bonded grindstone 1 can be, for example, 5 to 20 volume %. The shape of the second filler 6 can be, for example, a spherical particle, a fibrous particle, a flake particle, or the like. In addition, the volume ratio of the first filler 5 to the first resin 30 and the volume ratio of the second filler 6 to the second resin 40 are different.

[0025] The friable filler 61 may have a lower Knoop hardness than the abrasive grains 2, and may be, for example, talc, pyrite, cryolite, etc. The median diameter of the friable filler 61 may be, for example, 100 to 150 μm. The retention reinforcing layer 3 does not contain the friable filler 61, or the content of the friable filler 61 per unit volume is less than that of the bonding portion 4. In this embodiment, the retention reinforcing layer 3 does not contain the friable filler 61.

[0026] As the thermally conductive filler 62, for example, graphite, Co, Fe (iron), Cu (copper), Ag (silver), tungsten disulfide, carbon nanotubes, etc. can be adopted. The median diameter of the thermally conductive filler 62 can be, for example, 0.2 to 80.0 μm. As the second filler 6, hollow spheres made of ceramics can also be adopted. The retention force reinforcing filler 51 has a higher Young's modulus than the thermally conductive filler 62, the first resin 30, and the second resin 40.

[0027] The second resin 40 of the bonding portion 4 bonds the retention reinforcing layer 3 covering the abrasive grains 2 to the crushable filler 61 or the thermally conductive filler 62. The second resin 40 covers the retention reinforcing layer 3, the crushable filler 61, and the thermally conductive filler 62. In this embodiment, the boundary between the second resin 40 and the first resin 30 is a mixture of the second resin 40 and the first resin 30. However, a configuration in which the second resin 40 is in close contact with the first resin 30 may also be adopted. The ratio of the volume of the second resin 40 to the volume of the entire resin bonded grinding wheel 1 is 10 to 30 volume %.

[0028] In this embodiment, the first resin 30 and the second resin 40 are different types of resin. Moreover, the first resin 30 and the second resin 40 are synthetic resins mainly composed of the same type of organic compound, and have different characteristics. In this embodiment, both the first resin 30 and the second resin 40 are resins synthesized using phenol as the main raw material. In this embodiment, the second resin 40 is made of benzoxazine resin. However, the first resin 30 and the second resin 40 can be the same resin.

[0029] 5. Manufacturing method of resin bond grinding wheel 1 Next, a manufacturing method of the resin bonded grindstone 1 of this embodiment will be described with reference to Fig. 5. The manufacturing method of the resin bonded grindstone 1 of this embodiment has a first step S1 and a second step S2. The first step S1 is a step of manufacturing the abrasive grains 2 covered with the retention reinforcing layer 3 using the abrasive grains 2, powder of the first resin 30, and the retention reinforcing filler 51.

[0030] The second step S2 is a step of manufacturing the resin-bonded grinding wheel 1 of this embodiment using the abrasive grains 2 covered with the retention-reinforcing layer 3 obtained in the first step S1, powder of the second resin 40, the crushable filler 61, and the thermally conductive filler 62.

[0031] 6. Effects Next, the effects of this embodiment will be described. In the resin bonded grinding wheel 1, the surface of the abrasive grains 2 is covered with a retention-reinforcing layer 3 containing a retention-reinforcing filler 51. Therefore, the resin bonded grinding wheel 1 can exert a high retention force for the abrasive grains 2 due to the retention-reinforcing layer 3, and it is easy to suppress the abrasive grains 2 from falling off. Therefore, it is easy to improve the grinding wheel life and ensure grinding performance. In addition, the bonded part 4 does not contain the retention-reinforcing filler 51, or the content of the retention-reinforcing filler 51 per unit volume is smaller than that of the retention-reinforcing layer 3. Therefore, when grinding a workpiece, the bonded part 4 is easy to retreat from the abrasive grains 2, and it is easy to reduce the grinding resistance. As a result, it is possible to improve the grinding performance.

[0032] That is, since the retention reinforcing layer 3 contains the retention reinforcing filler 51 dispersed therein, the elastic modulus of the retention reinforcing layer 3 is increased, and the abrasive grains 2 can be firmly held. Therefore, even if the load on the abrasive grains 2 increases during grinding of a workpiece made of hard brittle ceramics, the abrasive grains 2 can be reliably held, and the falling off of the abrasive grains 2 can be suppressed. Therefore, the life of the grindstone can be improved and the grinding performance can be reliably ensured. On the other hand, since the bonded portion 4 does not contain the retention reinforcing filler 51 or contains less retention reinforcing filler 51 per unit volume than the retention reinforcing layer 3, the elastic modulus is likely to be lower than that of the retention reinforcing layer 3, and the bonded portion 4 is likely to recede from the abrasive grains 2 during grinding of the workpiece. Therefore, during grinding of the workpiece, the amount of protrusion of the abrasive grains 2 from the bonded portion 4 can be maintained, and further, the increase in grinding resistance due to the bonded portion 4 coming into contact with the workpiece can be suppressed. As a result, the grinding performance can be improved and the occurrence of so-called smacking can be suppressed.

[0033] The thickness of the retention reinforcing layer 3 is 1 / 20 or more of the median diameter of the abrasive grains 2. Therefore, the abrasive grains 2 can be reliably and firmly held, and the abrasive grains 2 can be reliably prevented from falling off. In addition, the thickness of the retention reinforcing layer 3 is preferably 1 / 15 or more of the median diameter of the abrasive grains 2. In this case, the abrasive grains 2 can be more reliably prevented from falling off.

[0034] The median diameter of the abrasive grains 2 is 25 to 400 μm, and the thickness of the retention reinforcing layer 3 is 3 to 27 μm. Therefore, the amount of protrusion of the abrasive grains 2 from the bonded portion 4 during grinding can be ensured, and an increase in the surface pressure applied to the resin bonded grinding wheel 1 can be reliably suppressed. This makes it easier to further improve the grinding performance. Furthermore, the abrasive grains 2 can be reliably and firmly held, and the life of the grinding wheel can be further improved. In addition, the thickness of the retention reinforcing layer 3 is preferably 4 to 20 μm. In this case, the life of the grinding wheel can be further improved, and the grinding performance can be further improved.

[0035] The retention reinforcing layer 3 covers 80% or more of the surface of the abrasive grains 2. Therefore, the abrasive grains 2 can be firmly held and the falling off of the abrasive grains 2 can be reliably prevented. As a result, the grinding performance can be more reliably ensured and the life of the grindstone can be reliably improved. Moreover, it is preferable that the retention reinforcing layer 3 covers 95% or more of the surface of the abrasive grains 2. In this case, the abrasive grains 2 can be held even more firmly.

[0036] The retention-reinforcing filler 51 is made of at least one of metal and silicon carbide. Therefore, the retention of the abrasive grains 2 in the retention-reinforcing layer 3 can be reliably increased. In addition, in this embodiment, the retention-reinforcing filler 51 has a metal filler 511. Therefore, the thermal conductivity in the vicinity of the abrasive grains 2 is improved, and the heat generated during grinding can be easily dissipated to the outside. Therefore, the temperature rise of the resin-bonded grinding wheel 1 and the workpiece can be suppressed, and so-called grinding burn can be suppressed. As a result, the deterioration of the resin constituting the resin-bonded grinding wheel 1 can be suppressed, and the change in the shape of the workpiece and the deterioration of the quality of the finished surface can be suppressed.

[0037] The median diameter of the retention reinforcing filler 51 is 20% or less of the median diameter of the abrasive grains 2. Therefore, it is easy to arrange the retention reinforcing filler 51 in the retention reinforcing layer 3 in a uniformly dispersed state around the abrasive grains 2. Therefore, it is easy for the retention reinforcing layer 3 to hold the abrasive grains 2 more firmly. In addition, it is preferable that the median diameter of the retention reinforcing filler 51 is 10% or less of the median diameter of the abrasive grains 2. In this case, it is easy to disperse the retention reinforcing filler 51 more uniformly around the abrasive grains 2.

[0038] The median diameter of the retention reinforcing filler 51 is 2% or more of the median diameter of the abrasive grains 2. Therefore, by having the retention reinforcing filler 51 of a predetermined size or more, it is possible to reliably increase the retention of the abrasive grains 2 in the retention reinforcing layer 3. In addition, it is preferable that the median diameter of the retention reinforcing filler 51 is 5% or more of the median diameter of the abrasive grains 2. In this case, it is possible to further reliably increase the retention of the abrasive grains 2 in the retention reinforcing layer 3.

[0039] The median diameter of the retention reinforcing filler 51 is 2.5 to 20.0 μm. Therefore, the retention of the abrasive grains 2 in the retention reinforcing layer 3 can be reliably increased.

[0040] The ratio of the volume of the first resin 30 to the entire volume of the resin bonded grinding wheel 1 is 5 to 30 volume %. The ratio of the volume of the retention reinforcing filler 51 to the entire volume of the resin bonded grinding wheel 1 is 2 to 12 volume %. This makes it possible to reliably arrange a sufficient amount of the retention reinforcing filler 51 around the abrasive grains 2, and to easily arrange the retention reinforcing filler 51 in a reliably dispersed state. As a result, it is possible to reliably increase the retention of the abrasive grains 2 in the retention reinforcing layer 3, while stabilizing the processing quality by improving the uniformity of the structure in the retention reinforcing layer 3.

[0041] The first resin 30 is made of a novolac phenolic resin, which allows it to be cured in a short time and has high water resistance after curing.

[0042] The bonding part 4 is configured to include a second resin 40 and a second filler 6, and the second filler 6 includes a different type of filler from the first filler 5. Therefore, the bonding part 4 has a different composition from the holding power reinforcing layer 3. Therefore, the bonding part 4 can have a different function from the holding power reinforcing layer 3. That is, for example, a filler for reducing grinding resistance, such as a crushable filler 61, can be included in the bonding part 4. As a result, the grinding performance can be improved.

[0043] The volume ratio of the first filler 5 to the first resin 30 and the volume ratio of the second filler 6 to the second resin 40 are different. Therefore, it is easy to make the retention reinforcing layer 3 and the bonding portion 4 perform different functions. Specifically, it is possible to improve the retractability of the bonding portion 4 to the abrasive grains 2 while making the retention reinforcing layer 3 perform a high retention of the abrasive grains 2. In other words, for example, by increasing the volume ratio of the retention reinforcing filler 51 to the first resin 30 and decreasing the volume ratio of the thermally conductive filler 62 to the second resin 40, it is possible to increase the retention of the abrasive grains 2 while reducing the grinding resistance.

[0044] The second filler 6 contains friable filler 61 that is lower in hardness than the abrasive grains 2. Therefore, when the friable filler 61 comes into contact with the workpiece during grinding, the friable filler 61 easily breaks, and the bonded portion 4 easily recedes relative to the abrasive grains 2. This ensures that the amount of protrusion of the abrasive grains 2 from the bonded portion 4 can be maintained. Also, since the bonded portion 4 is less likely to come into contact with the workpiece during grinding, the grinding resistance is easily reduced. As a result, the grinding performance can be further improved.

[0045] The second filler 6 contains a thermally conductive filler 62 having a higher thermal conductivity than the second resin 40. This improves the thermal conductivity of the resin bonded grinding wheel 1, making it easier to dissipate heat generated during grinding to the outside. This makes it possible to suppress temperature increases in the resin bonded grinding wheel 1 and the workpiece. This makes it possible to suppress deterioration of the resin constituting the resin bonded grinding wheel 1, as well as changes in the shape of the workpiece and deterioration in the quality of the finished surface.

[0046] The ratio of the volume of the thermally conductive filler 62 to the entire volume of the resin bonded grinding wheel 1 is 5 to 20 volume %, so that the thermal conductivity of the resin bonded grinding wheel 1 can be reliably improved.

[0047] The volume ratio of the second resin 40 to the entire volume of the resin bonded grinding wheel 1 is 10 to 30 volume %. Therefore, the retention reinforcing layer 3 covering the abrasive grains 2 can be reliably bonded to the second filler 6, and the volume ratio of the abrasive grains 2, the first filler 5, and the second filler 6 to the entire resin bonded grinding wheel 1 can be made to be a predetermined ratio or more. As a result, both the grinding wheel life and grinding performance can be reliably secured.

[0048] The second resin 40 is made of a benzoxazine resin. Therefore, during grinding, the bonded portion 4 is easily retracted from the abrasive grains 2. As a result, the grinding resistance is easily reduced.

[0049] The first resin 30 and the second resin 40 are different types of resin. Therefore, the retention reinforcing layer 3 and the bonding portion 4 tend to have different functions. In other words, by using a resin that easily improves the retention of the abrasive grains 2 as the first resin 30 and a resin that easily promotes the retreat of the bonding portion 4 relative to the abrasive grains 2 during grinding as the second resin 40, it is possible to improve the grinding performance while improving the life of the grinding wheel.

[0050] Each abrasive grain 2 is covered with a retention reinforcing layer 3. This ensures a sufficient distance between the abrasive grains 2, making it easy to reduce the grinding resistance during grinding. As a result, it is easy to improve the grinding performance.

[0051] The interval D1 between the abrasive grains 2 is 6 to 54 μm. Therefore, the number of abrasive grains 2 acting on the workpiece during grinding can be reliably secured while the distance between the abrasive grains 2 is reliably secured. As a result, the grinding performance can be reliably improved. Moreover, it is preferable that the interval D1 is 20 to 40 μm. In this case, the grinding performance can be further reliably improved.

[0052] The abrasive grain ratio is 35% by volume or less. This makes it easier to increase the spacing between the abrasive grains 2 and reduce the grinding resistance during grinding. The abrasive grain ratio is preferably 25% by volume or less. In this case, it is easier to increase the spacing between the abrasive grains 2 even more. The abrasive grain ratio is more preferably 20% by volume or less. In this case, it is easier to increase the spacing between the abrasive grains 2 even more.

[0053] The abrasive grain ratio is 6 volume % or more. Therefore, the number of abrasive grains 2 acting on the workpiece during grinding can be secured. As a result, the desired grinding performance can be secured.

[0054] In the manufacturing method of the resin bonded grinding wheel 1 of this embodiment, the resin bonded grinding wheel 1 is manufactured using abrasive grains 2 coated with a retention reinforcing layer 3. Therefore, it is possible to manufacture a resin bonded grinding wheel 1 in which the spacing between the abrasive grains 2 is reliably secured. Therefore, it is possible to manufacture a resin bonded grinding wheel 1 that can reduce the grinding resistance during grinding.

[0055] As described above, according to this embodiment, it is possible to provide a resin bonded grinding wheel that can improve the grinding performance by ensuring the abrasive grain retention and thereby improving the wheel life.

[0056] (Experimental Example 1) In this example, the bending strength was measured using a resin bonded grindstone of Example 1 having a retention reinforcing layer with a basic structure similar to that of the first embodiment, and a resin bonded grindstone 9 of Comparative Example 1 having no retention reinforcing layer as shown in FIG. 7. The bending strength was measured by a four-point bending test based on "JISR1601:2008 Room Temperature Bending Strength Test Method for Fine Ceramics". The resin bonded grindstone 9 of Comparative Example 1 shown in FIG. 7 was manufactured using abrasive grains 2, retention reinforcing filler 51, resin powder having the same composition as the first resin, friable filler 61, and thermally conductive filler 62. The resin bonded grindstone 9 of Comparative Example 1 has a resin bonded portion 91 that bonds the abrasive grains 2 together as shown in FIG. 7, and the resin bonded portion 91 contains the retention reinforcing filler 51, the friable filler 61, and the thermally conductive filler 62. Furthermore, the respective volumetric ratios of the abrasive grains 2, the retention reinforcing filler 51, the friable filler 61, and the thermally conductive filler 62 to the entire volume of the resin bonded grinding wheel were set to the same ratios in Example 1 and Comparative Example 1.

[0057] As shown in the graph of FIG. 6, Example 1 has a 2 kgf / mm 2 It can be seen that the bending strength value is about the same. Generally, the higher the bending strength value, the better the grain retention and the better the structural strength of the resin-bonded grinding wheel. Therefore, from this result, it can be said that the resin-bonded grinding wheel of Example 1 can easily suppress the abrasive grains from falling off by retaining the abrasive grains in the retention-reinforcing layer, thereby improving the grinding performance. Furthermore, the resin-bonded grinding wheel of Example 1 can improve the grinding wheel life by improving the structural strength.

[0058] (Experimental Example 2) In this example, as shown in the graph of FIG. 8, the relationship between the grinding ratio and the current value was obtained using the resin bonded grinding wheel of Example 1 and the resin bonded grinding wheel 9 of Comparative Example 1. In this example, the evaluation was performed using a ceramic workpiece. The grinding ratio is the ratio of the volume of the workpiece ground off divided by the volume of the resin bonded grinding wheel worn off. For example, when the volume of the workpiece ground off is twice the volume of the resin bonded grinding wheel worn off, the grinding ratio is 2. In other words, the higher the grinding ratio, the smaller the wear amount of the resin bonded grinding wheel relative to the amount of the workpiece ground off. The current value is the current value of the motor (not shown) of the grinding device in which the resin bonded grinding wheel is installed, and is the load current value of the motor of the grinding device during grinding measured by a clamp meter. In general, the lower the current value of the motor of the grinding device during grinding, the sharper the resin bonded grinding wheel is, i.e., the higher the grinding performance is.

[0059] As shown in the graph of Fig. 8, it can be seen that Example 1 has a higher grinding ratio than Comparative Example 1. Specifically, the grinding ratio value of Comparative Example 1 is less than 100, whereas the grinding ratio value of Example 1 is approximately 140. From this result, it is considered that the resin bonded grinding wheel of Example 1 has abrasive grains covered with a retention reinforcing layer, which prevents the abrasive grains from falling off, thereby suppressing wear of the resin bonded grinding wheel.

[0060] Also, as shown in the graph of FIG. 8, it can be seen that the current value is lower in Example 1 compared to Comparative Example 1. Here, in the resin bonded grindstone of Example 1, the bonded portion does not contain a retention reinforcing filler, or the content of the retention reinforcing filler 51 per unit volume is smaller than that of the retention reinforcing layer. Therefore, it is considered that the grinding resistance of the resin bonded grindstone of Example 1 is smaller than that of the resin bonded grindstone 9 of Comparative Example 1, which contains the retention reinforcing filler 51 in the resin bonded portion 91 (see FIG. 7), because the bonded portion of the resin bonded grindstone of Example 1 is likely to recede from the abrasive grains when grinding a workpiece. In other words, the resin bonded grindstone of Example 1 can improve grinding performance. [Explanation of symbols]

[0061] REFERENCE SIGNS LIST 1...resin bonded grinding wheel, 2...abrasive grains, 3...retention-enhancing layer, 4...bonding portion, 5...first filler, 30...first resin, 40...second resin, 51...retention-enhancing filler

Claims

1. A plurality of abrasive grains; a retention reinforcing layer that includes a first resin and a first filler, covers a surface of the abrasive grains, and holds the abrasive grains; a bonding portion that has a composition different from that of the retention reinforcing layer, contains a second resin, and bonds the retention reinforcing layers that cover the abrasive grains together; Equipped with The first filler includes at least a retention-enhancing filler having a higher elastic modulus than the first resin, A resin-bonded grinding wheel, wherein the bonding portion does not contain the retention-enhancing filler or has a smaller content of the retention-enhancing filler per unit volume than the retention-enhancing layer.

2. the bonding portion is configured to include the second resin and a second filler, The resin bonded abrasive wheel of claim 1 , wherein the second filler comprises a different type of filler than the first filler.

3. 3. The resin bonded abrasive wheel of claim 2, wherein a volume ratio of the first filler to the first resin is different from a volume ratio of the second filler to the second resin.

4. The resin bonded grinding wheel according to any one of claims 1 to 3, wherein the first resin and the second resin are different types of resin.

5. the first resin is a novolac phenolic resin; 5. The resin bonded abrasive wheel of claim 4, wherein the second resin is a benzoxazine resin.

6. The median diameter of the abrasive grains is 25 to 400 μm; The resin bonded grinding wheel according to any one of claims 1 to 3, wherein the thickness of the retention reinforcing layer is 3 to 27 µm.

7. 7. The resin bonded grinding wheel according to claim 6, wherein the spacing between the abrasive grains is 6 to 54 μm.

8. 4. The resin-bonded grinding wheel according to claim 1, wherein the median diameter of the retention-enhancing filler is 20% or less of the median diameter of the abrasive grains.

9. 9. The resin bonded grinding wheel according to claim 8, wherein the median diameter of the retention enhancing filler is 2.5 to 20.0 μm.

10. 4. The resin-bonded grindstone according to claim 1, wherein the retention-reinforcing layer covers 80% or more of the surface of the abrasive grains.

11. The resin bonded grinding wheel according to any one of claims 1 to 3, wherein the retention enhancing filler is made of at least one of a metal and silicon carbide.

12. 4. The resin-bonded grinding wheel according to claim 2 or 3, wherein the second filler contains at least one of a friable filler having a lower hardness than the abrasive grains and a thermally conductive filler having a higher thermal conductivity than the second resin.

13. The ratio of the volume of the first resin to the volume of the entire resin bonded grinding wheel is 5 to 30 volume %; 4. The resin bonded grinding wheel according to claim 1, wherein the ratio of the volume of the retention reinforcing filler to the volume of the entire resin bonded grinding wheel is 2 to 12 volume %.

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