Grinding stone and method for manufacturing grinding stones

Abstract

To provide grinding wheels and methods for manufacturing grinding wheels that have a low environmental impact. [Solution] The grinding wheels 10 and 20 are formed by bonding abrasive grains A with a binder B. The binder B is solid before processing the workpiece 2, and melts on the workpiece 2 side during processing. As a result, the binder B functions as at least one of a lubricant and a cleaning agent related to processing. Furthermore, the average particle size of the abrasive grains A in the grinding wheels 10 and 20 at locations shallow from the processing surface 11, which is the surface on the workpiece 2 side, is larger than the average particle size of the abrasive grains A at locations deeper from the processing surface 11.

Description

Technical Field

[0001] The disclosed technology relates to a grinding stone formed by binding abrasive grains with a binder and a method for manufacturing the grinding stone.

Background Art

[0002] Generally, a grinding stone is manufactured by binding abrasive grains with a binder. For example, Patent Document 1 discloses a method for manufacturing a grinding stone by filling a mixed powder of abrasive grains and a binder into the inside of a mold, molding it, and then performing firing.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the processing of a workpiece using a general grinding stone manufactured as described above, a processing fluid that functions as, for example, a lubricant or a coolant is supplied to the processing area between the grinding stone and the workpiece. Such a processing fluid for lubrication or the like is necessary during the processing of the workpiece, but is unnecessary for the processed product. And, by using a large amount of the processing fluid, for example, there were various problems. Specifically, for example, there is a problem that the load on the natural environment increases as more processing fluid is used.

[0005] An object of the disclosed technology is to provide a grinding stone and a method for manufacturing the grinding stone with a low environmental load.

Means for Solving the Problems

[0006] One aspect of the disclosed technology is a grinding wheel formed by bonding abrasive grains with a binder, wherein the binder is solid before processing the workpiece and melts on the workpiece side during processing, thereby functioning as at least one of a lubricant and a cleaning agent related to processing, and the average particle size of the abrasive grains in the area shallow from the processing surface, which is the surface of the workpiece, is larger than the average particle size of the abrasive grains in the area deeper from the processing surface.

[0007] In machining using this grinding wheel, there is no need to separately use lubricants and cleaning agents that have functions related to the molten binder. Therefore, in machining using this grinding wheel, the amount of machining fluid used can be reduced, lowering the environmental burden. Furthermore, in machining using this grinding wheel, the abrasive grains supplied between the workpiece and the grinding wheel become smaller as the workpiece is machined. In other words, this grinding wheel can be used to perform machining for multiple different purposes. Specifically, for example, rough machining to finish machining can be performed using this grinding wheel. [Effects of the Invention]

[0008] According to the disclosed technology, a grinding wheel and a method for manufacturing a grinding wheel that have a low environmental impact are provided. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows a processing apparatus capable of processing a workpiece using a grinding wheel according to the embodiment. [Figure 2] This is a schematic diagram of a cross-section of a grinding wheel according to the first embodiment. [Figure 3] This is a diagram illustrating the manufacturing method of a grinding wheel according to the first embodiment. [Figure 4] This is a schematic diagram of a cross-section of a grinding wheel according to the second embodiment. [Figure 5] This is a diagram illustrating the manufacturing method of a grinding wheel according to the second embodiment. [Figure 6] This figure shows abrasive particles supplied onto the surface of a solid binder. [Figure 7] This diagram shows the state in which abrasive particles supplied onto the surface of a solid binder become embedded in the solid binder. [Modes for carrying out the invention]

[0010] Hereinafter, embodiments of the disclosed technology will be described in detail with reference to the attached drawings. First, the first embodiment will be described, and then other embodiments different from the first embodiment will be described.

[0011] <First Embodiment> First, Figure 1 will illustrate a processing apparatus 1 capable of grinding and polishing a workpiece 2 using a grinding wheel 10 according to this embodiment. The grinding wheel 10 used in the processing apparatus 1 is plate-shaped. The grinding wheel 10 has a circular outer circumference. The grinding wheel 10 has a processing surface 11 and a base surface 12. The processing surface 11 and the base surface 12 are the end faces in the thickness direction of the plate-shaped grinding wheel 10. The processing surface 11 is the surface facing the workpiece 2. The grinding wheel 10 can grind and polish the workpiece 2 by bringing the workpiece 2 into contact with the processing surface 11. The base surface 12 is the back surface opposite to the processing surface 11.

[0012] The processing device 1 comprises a grinding wheel holder 3, a workpiece holder 4, a rotation drive unit 5, and a pressing unit 6. The grinding wheel holder 3 holds the grinding wheel 10 on its base surface 12 side. In this embodiment, the grinding wheel holder 3 holds the grinding wheel 10 with the processing surface 11 of the grinding wheel 10 facing upwards. The workpiece holder 4 holds the workpiece 2.

[0013] The rotary drive unit 5 can rotate the grinding wheel holder 3. This moves the machining surface 11 of the grinding wheel 10, which is held by the grinding wheel holder 3, so that it slides against the workpiece 2. The pressing unit 6 can press the workpiece holder 4 downwards with a predetermined pressure. This presses the workpiece 2, which is held by the workpiece holder 4, against the machining surface 11 of the grinding wheel 10.

[0014] The processing device 1 can process the workpiece 2 by rotating the grinding wheel 10 at a predetermined peripheral speed and pressing the workpiece 2 against the processing surface 11 of the grinding wheel 10. Furthermore, the processing device 1 can remove the workpiece 2 from the workpiece holder 4 by releasing its grip. This allows the processing device 1 to process multiple workpieces 2 while replacing them. Additionally, the processing device 1 can remove the grinding wheel 10 from the grinding wheel holder 3 by releasing its grip. This allows the processing device 1 to process workpieces 2 while replacing worn-out grinding wheels 10.

[0015] Figure 2 is a schematic cross-sectional view of the grinding wheel 10 of this embodiment. Figure 2 shows the initial state of the grinding wheel 10 before processing the workpiece 2. As shown in Figure 2, the grinding wheel 10 is composed of abrasive grains A and a binder B. The abrasive grains A are formed by bonding the abrasive grains A with the binder B. Specifically, as abrasive grains A, for example, diamond abrasive grains, CBN (cubic boron nitride) abrasive grains, alumina-based abrasive grains, silicon carbide-based abrasive grains, silicon oxide-based abrasive grains, cerium oxide-based abrasive grains, zirconia-based abrasive grains, chromium oxide-based abrasive grains, etc., as well as polymer / resin particle-based abrasive grains, etc., can be used. The type of abrasive used in the grinding wheel 10 can be determined according to the material of the workpiece 2 and the purpose of processing.

[0016] The binder B in this form is solid before processing the object to be processed 2, and by melting on the side of the object to be processed 2 during the processing of the object to be processed 2, it can be used as at least one of the lubricant and cleaning agent related to the processing. That is, the binder B exhibits at least one of the lubricating function and the cleaning function during processing. The lubricating function is a function that can improve the processing efficiency by reducing the friction between the grinding wheel 10 and the object to be processed 2 and suppressing the wear of the grinding wheel 10 and the like. The cleaning function is a function of removing the chips that have fallen off the object to be processed 2 due to processing by washing them away from the processing area between the grinding wheel 10 and the object to be processed 2. Specific examples of the binder B having such functions include water, ethanol, surfactants, mixtures thereof, and the like.

[0017] In this form, water is used as the binder B. As a result, the binder B in this form functions well as both the lubricant and the cleaning agent related to the processing. Also, in the form where water is used as the binder B, it has a cleaning function of washing away the chemicals and the like adhering to the object to be processed 2 during processing by the grinding wheel 10. Furthermore, since the binder B in this form is ice in the grinding wheel 10, it can also exhibit a good cooling function of suppressing the temperature rise during the processing of the object to be processed 2. In addition, by using water as the binder B, there is no need to use a processing fluid harmful to the human body. Therefore, the impact on the operator engaged in the processing using the grinding wheel 10 is also reduced. That is, the processing environment can also be improved compared to the conventional case. Also, the grinding wheel 10 using water as the binder B is inexpensive.

[0018] In some cases, it may be preferable to use pure water such as purified water as the binder B. This is because, for example, since there are few impurities, it is possible to further suppress the adhesion of impurities to the object to be processed 2.

[0019] FIG. 2 shows a grinding wheel 10, with a first region 10X, a second region 10Y, and a third region 10Z. In FIG. 2, the boundaries of the first region 10X, the second region 10Y, and the third region 10Z are indicated by virtual two-dot chain lines. The first region 10X is a region located closer to the machining surface 11 than either the second region 10Y or the third region 10Z. The first region 10X of the grinding wheel 10 in this embodiment is a region that includes the machining surface 11. The second region 10Y is a region located deeper than the first region 10X in the depth direction from the machining surface 11. The third region 10Z is a region located deeper than the second region 10Y in the depth direction from the machining surface 11. The third region 10Z of this embodiment is a region that includes the base surface 12. Also, the second region 10Y is a region located between the first region 10X and the third region 10Z in the depth direction from the machining surface 11.

[0020] As shown in FIG. 2, the grinding wheel 10 includes, as abrasive grains A, a first type of abrasive grain A1, a second type of abrasive grain A2, and a third type of abrasive grain A3. The first type of abrasive grain A1, the second type of abrasive grain A2, and the third type of abrasive grain A3 each have a different particle size. That is, the grinding wheel 10 is manufactured using the first type of abrasive grain A1, the second type of abrasive grain A2, and the third type of abrasive grain A3, which have different average particle sizes. The first type of abrasive grain A1 has a larger average particle size than either the second type of abrasive grain A2 or the third type of abrasive grain A3. The second type of abrasive grain A2 has a larger average particle size than the third type of abrasive grain A3. In this embodiment, the average particle size of the abrasive grains A is based on the median diameter, which is the particle size at the 50% integrated value in the volume-based particle size distribution obtained by the laser diffraction / scattering method.

[0021] In this embodiment, the first region 10X of the grinding wheel 10 has a higher proportion of Type 1 abrasive grains A1 among all the abrasive grains A it contains compared with both the second region 10Y and the third region 10Z. The second region 10Y has a higher proportion of Type 1 abrasive grains A1 among all the abrasive grains A it contains compared with both the third region 10Z. Furthermore, in this embodiment, the second region 10Y has a higher proportion of Type 2 abrasive grains A2 among all the abrasive grains A it contains compared with both the first region 10X and the third region 10Z. In addition, the third region 10Z has a higher proportion of Type 3 abrasive grains A3 among all the abrasive grains A it contains compared with both the first region 10X and the second region 10Y.

[0022] Therefore, in the first region 10X of the grinding wheel 10, the average particle size of the abrasive grains A contained is larger than that of both the second region 10Y and the third region 10Z. Also, in the second region 10Y, the average particle size of the abrasive grains A contained is larger than that of the third region 10Z. In other words, in the grinding wheel 10 of this embodiment, the average particle size of abrasive grains A in areas shallow from the machined surface 11 is larger than the average particle size of abrasive grains A in areas deeper from the machined surface 11. Furthermore, in the grinding wheel 10 of this embodiment, the distribution of the average particle size of abrasive grains A in the depth direction from the machined surface 11 has a gradient distribution where the size is larger in areas shallower from the machined surface 11 and smaller in areas deeper from the machined surface 11.

[0023] In a processing apparatus 1 using such a grinding wheel 10, first, the workpiece 2 is processed by the first region 10X of the grinding wheel 10. After the processing of the workpiece 2 by the first region 10X of the grinding wheel 10 has progressed and the first region 10X has been consumed, the workpiece 2 is processed by the second region 10Y. After the processing of the workpiece 2 by the second region 10Y of the grinding wheel 10 has progressed and the second region 10Y has been consumed, the workpiece 2 is processed by the third region 10Z.

[0024] In other words, the grinding wheel 10 in this embodiment can perform machining on the workpiece 2 in the order of the first region 10X, the second region 10Y, and the third region 10Z. Furthermore, the average particle size of the abrasive grains A of the grinding wheel 10 is smaller at the deeper position in the depth direction from the machining surface 11, where it appears on the surface and comes into contact with the workpiece 2. Therefore, as the grinding wheel 10 continues to machine the workpiece 2, the particle size of the abrasive grains A supplied to the machining region between the grinding wheel 10 and the workpiece 2 becomes smaller.

[0025] Furthermore, in the initial stages after the start of machining, the grinding wheel 10 can machine the workpiece 2 using abrasive grains A with a larger particle size. In other words, the grinding wheel 10 can perform rough machining on the workpiece 2 in the early stages of the machining process. As time progresses after the start of machining, the grinding wheel 10 can machine the workpiece 2 using abrasive grains A with a finer particle size. Therefore, in the later stages of the machining process, the grinding wheel 10 can perform finish machining on the machined surface of the workpiece 2. Moreover, in this embodiment of the grinding wheel 10, because the distribution of the average particle size of the abrasive grains A is sloped as described above, the size of the abrasive grains A can be changed drastically from rough machining to finish machining of the workpiece 2. Furthermore, since multiple types of machining for different purposes can be performed with a single grinding wheel 10, the number of machining steps can be reduced. This also shortens the machining time and reduces machining costs.

[0026] Next, the manufacturing method of the grinding wheel 10 in this embodiment will be described. The grinding wheel 10 is manufactured by dispersing abrasive grains A in a liquid binder B and then solidifying the binder B. As mentioned above, the grinding wheel 10 in this embodiment uses multiple types of abrasive grains A, each with a different average particle size. That is, the grinding wheel 10 in this embodiment can be manufactured by dispersing first-type abrasive grains A1, second-type abrasive grains A2, and third-type abrasive grains A3, each with a different average particle size, in a liquid binder B and then solidifying the binder B in that state.

[0027] To solidify the liquid binder B, the temperature of the binder B must be below its freezing point. That is, the binder B is solidified by cooling the liquid binder B to a temperature below its freezing point. This allows the solidified binder B to bind the abrasive grains A, thereby manufacturing the grinding wheel 10. Dispersion of the abrasive grains A into the liquid binder B can be performed, for example, by stirring while the temperature of the binder B is above its freezing point. Even if the temperature of the binder B is below its freezing point while stirring, the abrasive grains A can still be dispersed in the liquid binder B until the solidification of the liquid binder B progresses. Therefore, the abrasive grains A may be dispersed in the liquid binder B in an environment below its freezing point.

[0028] The binder B can be solidified while stirring to disperse the abrasive grains A in the liquid binder B, for example, as shown in Figure 3. Figure 3 shows a stirring device 50 that can be used in the manufacture of the grinding wheel 10. The stirring device 50 has stirring blades 51 for stirring. The abrasive grains A and binder B are housed inside a container 52. The container 52 contains abrasive grains A1 (first type), A2 (second type), and A3 (third type) as abrasive grains A. The binder B shown in Figure 3 is in liquid form.

[0029] When a grinding wheel is manufactured using the stirring device 50 shown in Figure 3, the stirring blade 51, which was stirring in the binder B, becomes fixed in the solidified binder B. The stirring blade 51 fixed in the binder B can then be removed, for example, by melting the binder B around the stirring blade 51 that is fixing it. Alternatively, the stirring blade 51 fixed in the binder B can also be removed, for example, by destroying the binder B around the stirring blade 51 that is fixing it. This allows the grinding wheel 10 to be manufactured.

[0030] As shown in Figure 3, abrasive grains A with a larger average particle size tend to sink more easily in the stirred liquid binder B than abrasive grains A with a smaller average particle size. Therefore, in this manufacturing method, the parts of the grinding wheel 10 that were on the lower side in the direction of gravity during the solidification of the binder B will contain larger abrasive grains A. In other words, this manufacturing method makes it possible to produce a grinding wheel 10 in which the distribution of the average particle size of abrasive grains A is larger on the lower side in the direction of gravity during the solidification of the binder B and smaller on the upper side in the direction of gravity. In the manufactured grinding wheel 10, the surface that was on the lower side in the direction of gravity during cooling can be used as the machined surface 11, and the surface that was on the upper side in the direction of gravity can be used as the base surface 12.

[0031] The grinding wheel 10 according to this embodiment allows for a wide range of designs to exhibit characteristics that meet the requirements for processing the workpiece 2. In other words, the volume ratio of abrasive grains A in the grinding wheel 10 can be determined considering the required lifespan, self-sharpening action, etc., depending on the application of the grinding wheel 10. Specifically, when the grinding wheel 10 of this embodiment is used for general purposes, the volume ratio of abrasive grains A can be within the range of 0.1% to 62.0%. Furthermore, in the grinding wheel 10 of this embodiment, the volume ratio of abrasive grains A can be within the range of 0.1% to 5.0%. This allows the binder B melted from the grinding wheel 10 to fully exert its lubricant or cleaning agent effect. In addition, if the grinding wheel 10 contains a surfactant, its effect can also be fully exerted. Moreover, it is possible to perform good processing of materials such as glass, silicon wafers, sapphire, as well as soft calcium oxide-containing glass and optical fluorite.

[0032] <Second Embodiment> Next, a second embodiment different from the above embodiment will be described. In the second embodiment, the manufacturing method and structure of the grinding wheel differ from the above embodiment. In this embodiment, the parts that differ from the above embodiment will be described. Parts that are not described can be the same as in the above embodiment.

[0033] Figure 4 is a schematic cross-sectional view of the grinding wheel 20 of this embodiment. Figure 4 shows the initial state of the grinding wheel 20 before machining the workpiece 2. As shown in Figure 4, the grinding wheel 20 is also composed of abrasive grains A and a binder B. The same abrasive grains A and binder B as in the above embodiment can be used.

[0034] Figure 4 shows the first layer 20X, the second layer 20Y, and the third layer 20Z of the grinding wheel 20. In Figure 4, the boundaries of the first layer 20X, the second layer 20Y, and the third layer 20Z are indicated by dashed lines. However, these boundaries are not always clearly defined on the grinding wheel 20. The first layer 20X of the grinding wheel 20 is located closer to the machined surface 21 than both the second layer 20Y and the third layer 20Z. In this embodiment, the first layer 20X of the grinding wheel 20 is the region that includes the machined surface 21. The second layer 20Y is the region located deeper than the first layer 20X in the depth direction from the machined surface 21. The third layer 20Z is the region located deeper than the second layer 20Y in the depth direction from the machined surface 21. In this embodiment, the third layer 20Z is the region that includes the base surface 22. Furthermore, the second layer 20Y is a region located between the first layer 20X and the third layer 20Z in the depth direction from the processed surface 21.

[0035] As shown in Figure 4, the grinding wheel 20 contains abrasive grains A1 (Type 1), A2 (Type 2), and A3 (Type 3). In this embodiment of the grinding wheel 20, A1 (Type 1), A2 (Type 2), and A3 (Type 3) are contained in the first layer 20X, the second layer 20Y, and the third layer 20Z, respectively. In this embodiment of the grinding wheel 20, neither A2 (Type 2) nor A3 (Type 3) is contained in the first layer 20X. Neither A1 (Type 1) nor A3 (Type 3) is contained in the second layer 20Y. Neither A1 (Type 1) nor A2 (Type 2) is contained in the third layer 20Z.

[0036] Furthermore, in this embodiment of the grinding wheel 20, the average particle size of abrasive grains A in the second layer 20Y is smaller than the average particle size of abrasive grains A in the first layer 20X. In addition, the average particle size of abrasive grains A in the third layer 20Z is even smaller than the average particle size of abrasive grains A in the second layer 20Y. In other words, even in this embodiment of the grinding wheel 20, the average particle size of abrasive grains A in areas shallow to the machining surface 21 is larger than the average particle size of abrasive grains A in areas deep to the machining surface 21.

[0037] Furthermore, in this embodiment of the grinding wheel 20, when used in the processing device 1, first, the first layer 20X of the grinding wheel 20 processes the workpiece 2. After the processing of the workpiece 2 by the first layer 20X of the grinding wheel 20 progresses and the first layer 20X is consumed, the workpiece 2 is processed by the second layer 20Y. After the processing of the workpiece 2 by the second layer 20Y of the grinding wheel 20 progresses and the second layer 20Y is consumed, the workpiece 2 is processed by the third layer 20Z.

[0038] In other words, even with this embodiment of the grinding wheel 20, machining can be performed on the workpiece 2 in the order of the first layer 20X, the second layer 20Y, and the third layer 20Z. Furthermore, with respect to the depth direction from the machining surface 21, the average particle size of the abrasive grains A is smaller at the depth position where the abrasive grains appear on the surface at a later timing during the machining of the workpiece 2 and come into contact with the workpiece 2. For this reason, as the grinding wheel 20 continues to machine the workpiece 2, the particle size of the abrasive grains A supplied to the machining region between the grinding wheel 20 and the workpiece 2 becomes smaller.

[0039] As a result, even with the grinding wheel 20, rough machining of the workpiece 2 can be performed in the initial stages after the start of machining using the first type abrasive grains A1, which have a larger particle size. Furthermore, as time passes after the start of machining, the grinding wheel 20 can perform machining of the workpiece 2 using abrasive grains A with a finer particle size. In other words, towards the end of the machining time for the workpiece 2, the grinding wheel 20 can perform finishing machining on the machined surface of the workpiece 2 using the third type abrasive grains A3, which have a smaller particle size. Moreover, since the grinding wheel 20 of this embodiment has three layers, each with a different average particle size, it can perform machining for three different purposes. That is, the grinding wheel 20 of this embodiment can also appropriately perform machining from rough machining to finishing machining of the workpiece 2.

[0040] Next, the manufacturing method of the grinding wheel 20 in this embodiment will be described. The grinding wheel 20 is manufactured by repeatedly supplying abrasive grains A and liquid binder B, and solidifying the supplied binder B. Specifically, in this embodiment, first, as shown in Figure 5, second-type abrasive grains A2 and liquid binder B are supplied onto the surface of a pre-formed first layer 20X. The pre-formed first layer 20X is a layer formed by bonding first-type abrasive grains A1 with solid binder B before supplying second-type abrasive grains A2, etc. Furthermore, the liquid binder B supplied onto the surface of the first layer 20X is solidified. This bonds the second-type abrasive grains A2 with binder B. This makes it possible to form a second layer 20Y adjacent to the first layer 20X. Of the first layer 20X, the surface on which the second-type abrasive grains A2 and liquid binder B are supplied is the back surface, which is opposite to the surface that becomes the machining surface 21 of the grinding wheel 20.

[0041] The third layer 20Z can be formed in the same manner. That is, third-type abrasive grains A3 and liquid binder B are supplied onto the surface of the formed second layer 20Y, and the supplied binder B is solidified to bond the third-type abrasive grains A3. The second layer 20Y is a layer formed by bonding second-type abrasive grains A2 with solid binder B before supplying the third-type abrasive grains A3, etc. This makes it possible to form the third layer 20Z adjacent to the second layer 20Y. Of the second layer 20Y, the surface on which the third-type abrasive grains A3 and liquid binder B are supplied is the surface opposite to the first layer 20X side. This makes it possible to manufacture the grinding wheel 20. In the manufactured grinding wheel 20, the end face of the first layer 20X in the stacking direction of each formed layer can be used as the machined surface 21, and the end face of the third layer 20Z in the stacking direction can be used as the base surface 22.

[0042] In this embodiment, the first layer 20X, the second layer 20Y, and the third layer 20Z are formed in order. When forming each layer, stirring may be performed as appropriate to disperse the abrasive grains A in the liquid binder B. Specifically, for example, the first layer 20X can be formed by adding the first type abrasive grains A1 to the liquid binder B and solidifying the liquid binder B while stirring them. If the thickness of the layer to be formed is thin, the supplied binder B may be solidified without any special stirring of the supplied abrasive grains A and liquid binder B.

[0043] Furthermore, abrasive grains A supplied onto the surface of an already formed layer may be pressed toward the already formed layer after being supplied but before being bonded by the binder B. This will be explained using Figures 6 and 7. Figures 6 and 7 show the case in which a second layer 20Y is formed by supplying a second type abrasive grains A2 to the surface of the first layer 20X.

[0044] Figure 6 shows the already formed first layer 20X and the second type abrasive grains A2 supplied to the surface of the first layer 20X. The second type abrasive grains A2 shown in Figure 6 are supplied on top of the solid binder B related to the first layer 20X. Figure 7 shows the state in which the second type abrasive grains A2 are pressed toward the solid binder B related to the first layer 20X by the pressing surface 61 of the abrasive grain pressing unit 60. The pressing surface 61 of the abrasive grain pressing unit 60 is flat. As shown in Figure 7, the second type abrasive grains A2 are embedded in the solid binder B by being pressed by the abrasive grain pressing unit 60. Then, as shown in Figure 7, the second type abrasive grains A2 are bonded by the binder B while embedded in the solid binder B related to the first layer 20X. This forms the second layer 20Y adjacent to the first layer 20X.

[0045] Here, as shown in Figure 6, the supplied Type 2 abrasive grains A2 include not only those in contact with the surface of the solid binder B, but also those overlapping each other vertically. In other words, the position of the Type 2 abrasive grains A2 after supply but before being bonded by the binder B may not be constant in the direction of gravity (i.e., the vertical direction in Figure 6). If such Type 2 abrasive grains A2 are bonded by the binder B as is, a second layer 20Y is formed that has Type 2 abrasive grains A2 that are close to the machined surface 21 and Type 2 abrasive grains A2 that are further from the machined surface 21 than the aforementioned Type 2 abrasive grains A2.

[0046] In contrast, after supply, the second type abrasive grains A2, before being bonded by the binder B, are pressed and embedded in the solid binder B, thereby aligning their position in the direction of gravity, as shown in Figure 7. Therefore, by bonding the embedded second type abrasive grains A2 with the binder B to form the second layer 20Y, the distance of the second type abrasive grains A2 from the machining surface 21 can be adjusted with high precision. That is, a second layer 20Y can be formed in which the distance from the machining surface 21 to the second type abrasive grains A2 is constant. As a result, a grinding wheel 20 can be manufactured that can machine the workpiece 2 with high precision using the second layer 20Y.

[0047] The liquid binder B used to bond the Type 2 abrasive grains A2 embedded in the solid binder B can be supplied after the Type 2 abrasive grains A2 have been embedded in the solid binder B. Alternatively, the liquid binder B may be supplied together with the Type 2 abrasive grains A2 to the surface of the solid binder B. In other words, the Type 2 abrasive grains A2 should be embedded in the solid binder B after supply and before the liquid binder B solidifies.

[0048] Furthermore, after the formation of the second layer 20Y, the third layer 20Z can also be formed in the same way as the second layer 20Y, by embedding the third type abrasive grains A3 into the solid binder B related to the second layer 20Y. This allows for highly precise adjustment of the distance of the third type abrasive grains A3 from the machined surface 21 in the third layer 20Z as well. This results in a grinding wheel 20 with even higher machining accuracy.

[0049] In this embodiment, the procedure for manufacturing the grinding wheel 20 by forming the first layer 20X, the second layer 20Y, and the third layer 20Z in that order has been described. However, the grinding wheel 20 may also be manufactured by forming the third layer 20Z, the second layer 20Y, and the first layer 20X in that order. Alternatively, for example, the grinding wheel 20 can be manufactured by first forming the second layer 20Y, and then forming the first layer 20X and the third layer 20Z on both sides of it, respectively.

[0050] As described above, the grinding wheels 10 and 20 according to the above embodiment are formed by bonding abrasive grains A with a binder B. The binder B is solid before processing the workpiece 2 and melts on the workpiece 2 side during processing. As a result, the binder B functions as at least one of a lubricant and a cleaning agent related to processing. Furthermore, in the grinding wheels 10 and 20, the average particle size of abrasive grains A at shallow points from the processing surface 11, which is the surface of the workpiece 2, is larger than the average particle size of abrasive grains A at deeper points from the processing surface 11. As a result, in processing using the grinding wheels 10 and 20, it is not necessary to separately use a lubricant and a cleaning agent that functions with the melted binder B. For this reason, in processing using the grinding wheels 10 and 20, the processing fluid used can be reduced, and the environmental burden can be lowered. In addition, in processing using the grinding wheels 10 and 20, the abrasive grains A supplied between the workpiece 2 and the grinding wheels 10 and 20 become smaller as the processing of the workpiece 2 progresses. In other words, by using grinding wheels 10 and 20, it is possible to perform machining for multiple different purposes. Specifically, for example, rough machining to finish machining can be performed using grinding wheels 10 and 20.

[0051] The embodiments described above are merely illustrative and do not limit the disclosed technology in any way. Therefore, the disclosed technology can naturally be improved and modified in various ways without departing from its essence.

[0052] For example, the processing apparatus shown in the above embodiment is merely an example, and other processing apparatuses may be used. Specifically, as a processing apparatus that performs grinding and polishing using a grinding wheel, for example, one that rotates the workpiece and presses the grinding wheel against the rotating workpiece may be adopted. That is, for example, the rotational drive unit of the processing apparatus should be a drive unit that can slide at least one of the processing surface of the grinding wheel and the workpiece against the other. Also, for example, the pressing unit of the processing apparatus should be one that can press at least one of the grinding wheel and the workpiece against the other.

[0053] Furthermore, for example, the processing equipment may have a cooling function that can cool the grinding wheel. That is, for example, if a grinding wheel using water as a binder is used and processing is performed on a workpiece in a room temperature environment, the entire grinding wheel may melt depending on the processing time. In contrast, if the processing equipment has a cooling function for the grinding wheel, the life of the grinding wheel can be extended compared to when there is no cooling function. Specifically, such a cooling function could be, for example, one that lowers the temperature around the grinding wheel to below the ambient temperature of the processing equipment. Alternatively, for example, a grinding wheel holder that holds the grinding wheel may be used that has a cooling function. This can suppress melting of the base surface of the grinding wheel.

[0054] Furthermore, grinding wheels held in the processing equipment can be removed from the equipment by completely melting the binder. In other words, when replacing a grinding wheel held in the processing equipment, it is not always necessary to remove the grinding wheel that is already installed.

[0055] Furthermore, in the above embodiment, an example was described in which three types of abrasive grains with different average particle sizes were used. However, it is also possible to use two types of abrasive grains with different average particle sizes. Alternatively, for example, it is possible to use four or more types of abrasive grains with different average particle sizes.

[0056] Furthermore, in the case of grinding wheels, in addition to the average particle size of the abrasive grains, at least one of the volume density of the abrasive grains or the degree of dispersion of the abrasive grains may also differ depending on the depth from the machining surface. For example, if the volume density of the abrasive grains differs depending on the depth from the machining surface, the machining speed of the workpiece can be made different in areas where the volume density of the abrasive grains differs. Also, for example, in areas intended for rough machining in the thickness direction of the grinding wheel, if the desired machining can be performed even if the degree of dispersion of the abrasive grains is low, then it is not necessary to strictly control the degree of dispersion of the abrasive grains during the manufacturing of the grinding wheel, and the manufacturing of the grinding wheel can be made simpler.

[0057] Furthermore, the disclosed technology described above includes the following means 1 to means 9. [Means 1] A grinding wheel formed by the bonding of abrasive grains with a binder, The aforementioned binder is solid before processing the workpiece, and melts on the workpiece side during processing, thereby functioning as at least one of a lubricant and a cleaning agent related to the processing. A grinding wheel in which the average particle size of the abrasive grains in the area shallow from the workpiece surface is larger than the average particle size of the abrasive grains in the area deeper from the workpiece surface.

[0058] [Means 2] The grinding stone described in method 1, Regarding the depth direction from the processed surface, the grinding wheel has a smaller average particle size for abrasive grains at depths where the abrasive grains appear on the surface and come into contact with the workpiece at a later time during the processing of the workpiece.

[0059] [Means 3] A grinding stone according to means 1 or means 2, A grinding wheel in which the distribution of the average particle size of the abrasive grains in the depth direction from the machined surface is sloped such that the particle size is larger in areas shallower from the machined surface and smaller in areas deeper from the machined surface.

[0060] [Means 4] A grinding stone according to means 1 or means 2, It has a first layer, a second layer located deeper than the first layer when viewed from the processed surface, and a third layer located deeper than the second layer when viewed from the processed surface. The average particle size of the abrasive grains in the second layer is smaller than the average particle size of the abrasive grains in the first layer. A grinding wheel in which the average particle size of the abrasive grains in the third layer is even smaller than the average particle size of the abrasive grains in the second layer.

[0061] [Means 5] A grinding stone according to means 1 or means 2, The aforementioned binder is water, which is used in the grinding wheel.

[0062] [Means 6] A method for manufacturing a grinding wheel, which is a grinding wheel in which abrasive grains are bound together with a binder, Multiple types of abrasive grains, each with a different average particle size, are dispersed in the liquid binder. A method for manufacturing a grinding wheel, comprising bonding multiple types of abrasive grains together by solidifying the binder while the binder is dispersed in a liquid binder.

[0063] [Means 7] A method for manufacturing a grinding wheel, which is a grinding wheel in which abrasive grains are bound together with a binder, On the surface of a layer formed by bonding the first type of abrasive grains, which are abrasive grains with an average particle size different from the first type of abrasive grains, with the binder in a solid state, a second type of abrasive grains and the binder in liquid form are supplied. A method for manufacturing a grinding wheel, comprising solidifying the supplied binder to bond the supplied second type of abrasive grains.

[0064] [Means 8] A method for manufacturing a grinding wheel as described in means 7, A method for manufacturing a grinding wheel, wherein, after supplying the second type of abrasive grains, and before the liquid binder solidifies, the grains are pressed against the solid binder to create a state in which they are embedded in the solid binder.

[0065] [Means 9] A method for manufacturing a grinding wheel as described in any of means 6 to means 8, A method for manufacturing a grinding wheel using water as the binder. [Explanation of Symbols]

[0066] 10, 20: Sharpening stone 10X: 1st area 10Y: 2nd area 10Z: 3rd area 11, 21: Processed surface 20X: 1st layer 20Y: 2nd layer 20Z: 3rd layer 21: Machining surface A: Abrasive grains A1: Type 1 abrasive grains A2: Type 2 abrasive grain A3: Type 3 abrasive grains B: Binder

Claims

1. A grinding wheel formed by the bonding of abrasive grains with a binder, The aforementioned binder is solid before processing the workpiece, and melts on the workpiece side during processing, thereby functioning as at least one of a lubricant and a cleaning agent related to the processing. A grinding wheel in which the average particle size of the abrasive grains in the area shallow from the workpiece surface is larger than the average particle size of the abrasive grains in the area deeper from the workpiece surface.

2. A grinding wheel according to claim 1, Regarding the depth direction from the processed surface, the grinding wheel has a smaller average particle size for abrasive grains at depths where the abrasive grains appear on the surface and come into contact with the workpiece at a later time during the processing of the workpiece.

3. A grinding wheel according to claim 1 or claim 2, A grinding wheel in which the distribution of the average particle size of the abrasive grains in the depth direction from the machined surface is sloped such that the particle size is larger in areas shallower from the machined surface and smaller in areas deeper from the machined surface.

4. A grinding wheel according to claim 1 or claim 2, It has a first layer, a second layer located deeper than the first layer when viewed from the processed surface, and a third layer located deeper than the second layer when viewed from the processed surface. The average particle size of the abrasive grains in the second layer is smaller than the average particle size of the abrasive grains in the first layer. A grinding wheel in which the average particle size of the abrasive grains in the third layer is even smaller than the average particle size of the abrasive grains in the second layer.

5. A grinding wheel according to claim 1 or claim 2, The aforementioned binder is water, which is used in the grinding wheel.

6. A method for manufacturing a grinding wheel, which is a grinding wheel in which abrasive grains are bound together with a binder, Multiple types of abrasive grains, each with a different average particle size, are dispersed in the liquid binder. A method for manufacturing a grinding wheel, comprising bonding multiple types of abrasive grains together by solidifying the binder while the binder is dispersed in a liquid binder.

7. A method for manufacturing a grinding wheel, which is a grinding wheel in which abrasive grains are bound together with a binder, On the surface of a layer formed by bonding the first type of abrasive grains, which are abrasive grains with an average particle size different from the first type of abrasive grains, with the binder in a solid state, a second type of abrasive grains and the binder in liquid form are supplied. A method for manufacturing a grinding wheel, comprising solidifying the supplied binder to bond the supplied second type of abrasive grains.

8. A method for manufacturing a grinding wheel according to claim 7, A method for manufacturing a grinding wheel, wherein, after supplying the second type of abrasive grains, before the liquid binder solidifies, the grains are pressed against the solid binder, causing them to become embedded in the solid binder.

9. A method for manufacturing a grinding wheel according to any one of claims 6 to 8, A method for manufacturing a grinding wheel using water as the binder.

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