Porous composite abrasive grinding stone

Abstract

To provide a grindstone that has high durability, is less likely to form a deep cutting flaw in a workpiece and can restrain heat generated during processing.SOLUTION: A grindstone contains composite abrasive grains. The composite abrasive grains include first composite grind abrasive grains with first abrasive grains in a first binding material, and a plurality of the composite abrasive grains are bound to each other by another binding material so as to have pores opening on a surface. The composite abrasive grains may further include second composite abrasive grains with second abrasive grains fixed on surfaces of rubber particles by a second binding material. In that case, a mass ratio (B / (A+B)) of the content (B) of the second composite abrasive grains to the total quantity (A+B) of the content (A) of the first composite abrasive grains and the content (B) of the second composite abrasive grains may be 0.8 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Grinding wheels are widely known as tools for grinding and polishing workpieces. Among them, elastic grinding wheels, which have abrasive grains made of alumina (aluminum oxide), silicon carbide, diamond, cubic boron nitride (CBN), etc. dispersed in a rubber-elastic binder, are known to conform well to the surface shape of the workpiece.

[0003] Because the bond of elastic grinding wheels is flexible, there are problems such as: (1) when they come into contact with the surface of the workpiece, the abrasive grains are pushed into the bond, making it difficult to grind or polish the abrasive grains in a protruding state, (2) the bond absorbs the impact on the abrasive grains, making it difficult for the abrasive grains to break down and create new cutting edges, and (3) if a bond that wears easily is used to improve these problems, many of the abrasive grains will fall off without contributing to grinding or polishing. Because of these problems, elastic grinding wheels have been thought to have lower grinding power and a shorter lifespan than vitrified grinding wheels or resinoid grinding wheels.

[0004] To solve the above problems, a method was developed in which multiple abrasive grains are bound together using a resin binder to produce a "composite abrasive grain" as a mass aggregate, and this is used instead of regular abrasive grains. By dispersing this composite abrasive grain in a binder with rubber elasticity, an elastic grinding wheel with the same grinding power as pitrified grinding wheels and resinoid grinding wheels can be obtained (see Patent Document 1).

[0005] It has also been reported that by using a grinding wheel made by bonding together multiple powdered rubber particles with abrasive grains bonded to the surface using a resin binder, so that they have pores, it is possible to achieve both excellent grinding power and a precise and elegant finished surface (see Patent Document 2).

[0006] Furthermore, it has been reported that a grinding wheel in which porous inorganic composite abrasive grains, in which multiple abrasive grains are bonded together using a ceramic sintering agent or the like, are integrally bonded to a sponge-like porous rubber elastic compound, exhibits excellent conformability when machining curved surfaces and excellent uniformity in polishing (see Patent Document 3).

[0007] On the other hand, against the backdrop of recent increases in the complexity and sophistication of workpieces, there is an increasing demand for grinding wheels that are less likely to leave deep cutting marks on the workpiece and that can suppress the heat generated during processing. The grinding wheels disclosed in Patent Document 2 and Patent Document 3 are expected to be excellent in terms of less likely to leave deep cutting marks on the workpiece and in suppressing the heat generated during processing, but there are concerns about the grinding wheel disclosed in Patent Document 2 suffering from a decrease in performance due to the falling off of abrasive grains, and about the grinding wheel disclosed in Patent Document 3 suffering from insufficient strength and wear resistance of the grinding wheel itself. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special Publication No. 48-8678 [Patent Document 2] Special Publication No. 52-3148 [Patent Document 3] Special Publication No. 63-17594 Summary of the Invention [Problem to be solved by the invention]

[0009] The problem to be solved by the present invention is to provide a grinding wheel that is highly durable, does not easily leave deep cutting marks on a workpiece, and can suppress the heat generated during processing. [Means for solving the problem]

[0010] The embodiments of the present invention are as follows. [1] A grinding wheel containing composite abrasive grains, The composite abrasive includes a first composite abrasive having first abrasive grains dispersed in a first bond; A grinding wheel in which a plurality of the composite abrasive grains are bonded to each other by another binder so as to have pores opening to the surface. [2] The composite abrasive further includes a second composite abrasive in which the second abrasive is fixed to the surface of a rubber particle by a second binder; The grinding wheel according to [1], wherein the mass ratio (B / (A+B)) of the content of the second composite abrasive grains (B) to the total amount (A+B) of the content of the first composite abrasive grains (A) and the content of the second composite abrasive grains (B) is 0.8 or less. [3] The grinding wheel according to [2], wherein the second composite abrasive grains have a grain size of 0.1 to 5 mm. [4] The grinding wheel of [2] or [3], wherein the rubber particles have a rubber hardness of 30 or more as measured with a Type A durometer conforming to JIS K6253-3 and a rubber hardness of 80 or less as measured with a Type D durometer conforming to JIS K6253-3. [5] The grinding wheel according to any one of [1] to [4], wherein the porosity of the pores is 5 to 50% by volume. [6] The grindstone according to any one of [1] to [5], wherein the first composite abrasive grains have a grain size of 0.1 to 5 mm. [7] The grindstone according to any one of [1] to [6], wherein the first binder contains a phenolic resin. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a grinding wheel that is highly durable, is less likely to leave deep cutting marks on a workpiece, and can suppress the heat generated during processing. [Brief explanation of the drawings]

[0012] [Figure 1] 10 is a plot showing the temperature transition of the workpiece in each example and each comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0013] The grinding wheel of the present invention contains composite abrasive grains, and the composite abrasive grains include first composite abrasive grains in which first abrasive grains are dispersed in a first binder, and multiple composite abrasive grains are bonded to each other by another binder so as to have pores opening to the surface. Each component of the composite abrasive grain of the present invention will be described in detail below.

[0014] [First composite abrasive] The first composite abrasive grain is a composite abrasive grain in which first abrasive grains are dispersed in a first binder. The first composite abrasive grain preferably has a structure in which a plurality of first abrasive grains are dispersed in a matrix of the first binder. However, some of the first abrasive grains may be in contact with each other.

[0015] (First binder) The first binder functions as a matrix that fixes the multiple first abrasive grains in a dispersed state inside and on the surface, and is also a constituent that determines the general shape of the entire first composite abrasive grain.

[0016] Examples of the first binder include thermoplastic resins such as polyethylene, polypropylene, polyvinyl chloride, polystyrene, styrene-isoprene block copolymer, styrene-butadiene block copolymer, hydrogenated styrene-isoprene block copolymer, hydrogenated styrene-butadiene block copolymer, polyvinyl acetate, thermoplastic polyurethane, acrylonitrile-butadiene-styrene copolymer (ABS resin), polymethyl methacrylate, polyethyl methacrylate, polyamide, polyester, polycarbonate, and fluororesin; and thermosetting resins such as phenolic resin, urea resin, epoxy resin, melamine resin, polyurethane, and thermosetting polyimide.

[0017] In particular, the first binder preferably contains a thermosetting resin from the viewpoints of heat resistance and ease of molding into composite abrasive grains, and more preferably contains one selected from the group consisting of phenolic resin, urea resin, epoxy resin, melamine resin, and polyurethane, and even more preferably contains a phenolic resin from the viewpoints of heat resistance, flame retardancy, mechanical properties, oil resistance, chemical resistance, and economy. The first binder may be used alone or in combination of two or more kinds.

[0018] (First abrasive grain) The first abrasive grains are elements that actually come into contact with the workpiece and contribute to grinding and polishing when the workpiece is ground and polished using the grinding wheel of the present invention. A plurality of first abrasive grains are bonded to each other via a first binder and are present on the surface and inside of the grinding wheel.

[0019] There is no particular limitation on the shape of the first abrasive grains, and they can be selected from abrasive grains that are normally used in grinding wheels. The particle size of the first abrasive grains is preferably 0.18 to 0.5 mm, more preferably 0.2 to 0.35 mm, when the grinding stone is for rough finishing. Furthermore, the particle size is preferably 0.04 to 0.18 mm, more preferably 0.05 to 0.1 mm, when the grinding stone is for medium finishing. By ensuring that the particle size of the first abrasive grains is within an appropriate range, a processing rate suited to the processing conditions can be obtained. The particle size of the first abrasive grains can be classified by sieving or the like.

[0020] The first abrasive grains may contain a portion having a particle size outside the above range, in which case the abrasive grains having a particle size outside the above range preferably account for 10% by mass or less, and more preferably 5% by mass or less, of the total first abrasive grains.

[0021] Examples of materials for the first abrasive grains include alumina (aluminum oxide), zirconia (zirconium oxide), silica (silicon oxide), chromium oxide (chromium trioxide), cerium oxide, silicon carbide, diamond, emery powder, cubic boron nitride (CBN), etc. Among these, it is preferable that the first abrasive grains contain alumina or silicon carbide.

[0022] The first abrasive grains may be ceramic abrasive grains. In this specification, ceramic refers to a sintered body obtained by heat-treating and sintering inorganic powder or the like, and is polycrystalline. Ceramics also include those produced via the sol-gel method. Examples of ceramic abrasive grains include ceramic abrasive grains whose main component is alumina (preferably α-alumina). The first abrasive grains may be used singly or in combination of two or more types. The types and combinations of the first abrasive grains to be used may be appropriately selected depending on the conditions of grinding / polishing, etc., and the material of the workpiece.

[0023] The content of the first abrasive grains in the first composite abrasive grains is preferably 1 to 6 parts by mass, more preferably 1.5 to 5 parts by mass, even more preferably 2 to 4.5 parts by mass, and most preferably 2.5 to 4 parts by mass, per 1 part by mass of the first binder. When the content of the first abrasive grains is within an appropriate range, the grinding and polishing performance of the grinding wheel of the present invention becomes good.

[0024] (Structure and Shape of First Composite Abrasive Grain) The particle size of the first composite abrasive grains is preferably 0.1 to 5 mm. The particle size of the first composite abrasive grains can be classified by sieving or the like. The first composite abrasive grains may contain particles outside the above particle size range. In this case, the first composite abrasive grains outside the above particle size range preferably account for 15% by mass or less, more preferably 10% by mass or less, of the total first composite abrasive grains.

[0025] The particle size of the first composite abrasive grains can be appropriately selected from the above range depending on the application. For example, in grinding applications, the particle size of the first composite abrasive grains is more preferably 2 to 5 mm. In polishing applications, the particle size of the first composite abrasive grains is more preferably 0.1 to 2 mm. The first composite abrasive grains are in the form of a block. Although the outline of the block becomes complex due to the presence of the protruding first abrasive grains, it is preferable that the block has an approximately spherical or ellipsoidal shape overall.

[0026] The first composite abrasive grains may contain other components such as antioxidants, antistatic agents, colorants, fillers, light stabilizers, plasticizers, lubricants, flame retardants, and flame retardant assistants, as needed, within the range that does not impair the effects of the present invention. The amount of the first binder relative to the total amount of the first binder and the other components is preferably 80% by mass or more, and more preferably 90% by mass or more.

[0027] (First method for manufacturing composite abrasive grains) The first composite abrasive grain can be produced, for example, by mixing the raw materials using a mixer, passing the resulting mixture through a wire mesh to form granules, which are then granulated in a granulator, and heating the resulting composite abrasive grain precursor in an electric furnace or the like.

[0028] [Second composite abrasive] The composite abrasive grains contained in the grinding wheel of the present invention may optionally contain second composite abrasive grains in which second abrasive grains are fixed to the surface of rubber particles with a second binder. The second composite abrasive grains preferably have a structure in which multiple second abrasive grains are dispersed and bonded to the surface of rubber particles with the second binder. However, some of the second abrasive grains may be in contact with each other.

[0029] (Second binder) The second binder functions as an adhesive that bonds the rubber particles and the plurality of second abrasive grains together, and may cover the entire surface of the rubber particles or only a portion of the surface of the rubber particles.

[0030] Examples of the second binder include thermoplastic resins such as polyethylene, polypropylene, polyvinyl chloride, polystyrene, styrene-isoprene block copolymer, styrene-butadiene block copolymer, hydrogenated styrene-isoprene block copolymer, hydrogenated styrene-butadiene block copolymer, polyvinyl acetate, thermoplastic polyurethane, acrylonitrile-butadiene-styrene copolymer (ABS resin), polymethyl methacrylate, polyethyl methacrylate, polyamide, polyester, polycarbonate, and fluororesin; and thermosetting resins such as phenolic resin, urea resin, epoxy resin, melamine resin, polyurethane, and thermosetting polyimide.

[0031] Among these, from the viewpoint of heat resistance and abrasion resistance, it is preferable that the second binder contains a thermosetting resin, more preferably contains one selected from the group consisting of phenolic resin, urea resin, epoxy resin, melamine resin, and polyurethane, and even more preferably contains polyurethane.

[0032] The polyurethane may be produced by reacting, for example, a polyol, a polyisocyanate, and, if necessary, a polyamine, where polyol, polyisocyanate, and polyamine refer to compounds having two or more hydroxyl groups, isocyanate groups, and amino groups, respectively. The second binder may be used alone or in combination of two or more types.

[0033] (Second abrasive grain) The second abrasive grains are elements that actually come into contact with the workpiece and contribute to grinding and polishing when the workpiece is ground and polished using the grinding wheel of the present invention. A plurality of second abrasive grains are bonded to each other via a second binder and are present on the surface of the rubber particle. The second abrasive grains may be the same as those described above as the first abrasive grains.

[0034] The content of the second abrasive grains is preferably 1 to 25 parts by mass, more preferably 5 to 20 parts by mass, and even more preferably 10 to 15 parts by mass, per part by mass of the second binder. By ensuring that the content of the second abrasive grains is within an appropriate range, a good balance is achieved between the grinding and polishing performance of the grinding stone of the present invention and the resistance of the second abrasive grains to falling off.

[0035] (rubber particles) The rubber particles function as a carrier for supporting the secondary abrasive grains, and are also a component that determines the general shape of the entire secondary composite abrasive grain.

[0036] Examples of rubbers that may be used to make up the rubber particles include natural rubber, styrene-butadiene rubber, butadiene rubber, chloroprene rubber, acrylonitrile-butadiene rubber, hydrogenated nitrile rubber, isoprene rubber, butyl rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber (EPDM), acrylic rubber, fluororubber, and silicone rubber.

[0037] The particle size of the rubber particles is preferably 0.1 to 5 mm. The particle size of the rubber particles can be classified by a sieving method or the like. The rubber particles may contain some particles that do not fall within the above particle size range. In this case, the rubber particles that do not fall within the above particle size range preferably account for 15% by mass or less, and more preferably 10% by mass or less, of the total rubber particles.

[0038] The rubber particles preferably have a rubber hardness of 30 or more as measured with a Type A durometer conforming to JIS K6253-3, and a rubber hardness of 80 or less as measured with a Type D durometer conforming to JIS K6253-3. When the rubber hardness of the rubber particles is within an appropriate range, deep cutting marks are less likely to be formed in the workpiece, and a high processing rate, high stability in grinding and polishing, and good conformability to the workpiece surface can be achieved.

[0039] (Structure and shape of the second composite abrasive grain) The particle size of the second composite abrasive grains corresponds to the particle size of the rubber particles and is preferably 0.1 to 5 mm. The particle size of the second composite abrasive grains can be selected appropriately depending on the application. For example, in grinding applications, the particle size of the second composite abrasive grains is more preferably 2 to 5 mm. Furthermore, in polishing applications, the particle size of the second composite abrasive grains is more preferably 0.1 to 2 mm. Furthermore, the second composite abrasive grains are in a block shape. Although the outline becomes complex due to the presence of the protruding second abrasive grains, it is preferable that the overall shape be a solid with no significant difference in three-dimensional dimensions, such as a substantially regular polyhedron, a substantially spherical shape, or a substantially ellipsoidal shape.

[0040] The second composite abrasive grains may contain other components such as antioxidants, antistatic agents, colorants, fillers, light stabilizers, plasticizers, lubricants, flame retardants, and flame retardant assistants, as needed, within the range that does not impair the effects of the present invention. The amount of the second binder relative to the total amount of the second binder and the other components is preferably 80% by mass or more, and more preferably 90% by mass or more.

[0041] (Second method for manufacturing composite abrasive grains) The second composite abrasive grains can be produced, for example, by mixing raw materials using a stirrer, granulating the resulting mixture in a granulator, and heating the resulting composite abrasive grain precursor in an electric furnace or the like.

[0042] [Grinding stone] In the grinding wheel of the present invention, a plurality of composite abrasive grains are bonded to one another by another binder (hereinafter also referred to as "third binder") so as to have pores that open to the surface.

[0043] When the composite abrasive contains second composite abrasive grains, the mass ratio (B / (A+B)) of the content of the second composite abrasive grains (B) to the total amount (A+B) of the content of the first composite abrasive grains (A) and the content of the second composite abrasive grains (B) is preferably 0.8 or less. Depending on the application of the grinding wheel, the mass ratio may be, for example, in the range of 0.8 to 0.7, 0.7 to 0.5, 0.5 to 0.3, 0.3 to 0.1, or 0.1 to 0. For example, a small mass ratio is preferable for grinding applications, and a large mass ratio is preferable for polishing applications.

[0044] (Other binders (third binders)) As the third binder, the same material as that described above as the second binder can be used, and the materials described as being preferred as the second binder can also be suitably used.

[0045] The content of the third binder is preferably 0.1 to 2 parts by mass, more preferably 0.2 to 1 part by mass, and even more preferably 0.3 to 0.6 parts by mass, per 1 part by mass of the total of the first composite abrasive grains and the second composite abrasive grains.

[0046] (stomata) The grinding wheel of the present invention has pores that open to the surface. That is, the grinding wheel of the present invention does not have all of the spaces between the composite abrasive grains filled with the third binder, but rather has voids that extend from the surface to the interior of the grinding wheel, with each composite abrasive grain being partially bonded to another composite abrasive grain via the third binder.

[0047] The grinding wheel of the present invention preferably has a porosity of 5 to 50 volume %, more preferably 10 to 45 volume %, and even more preferably 20 to 40 volume % due to the pores that open to the surface. By keeping the porosity within an appropriate range, the grinding and polishing force and the strong bond between the composite abrasive grains are maintained, the heat generated during processing is suppressed, and deep cutting marks are less likely to be formed on the workpiece. In this specification, the term "porosity" refers to the ratio of the volume of pores that are open to the surface of the grinding wheel, and can be calculated using the following formula (1).

[0048] ·Calculation formula (1) Porosity (volume%) = (V1 / V0) x 100 V1: Total volume of pores open to the surface of the grinding wheel being measured V0: The volume of an imaginary grinding wheel that has the same external shape as the grinding wheel being measured and is densely packed with voids

[0049] For example, if the grinding wheel has a cylindrical outer shape with a diameter L and a height h, V0 in the above formula (1) is the volume of the cylinder, as shown in the following formula (2).

[0050] ·Calculation formula (2) V0=Pi×(L / 2) 2 ×h

[0051] V1 in the above formula (1) can be measured, for example, by the following procedures (1) to (6). (1) Pour water into a measuring cylinder and read the scale. (2) The entire grinding wheel to be measured is completely immersed in the water. (3) Remove any air bubbles adhering to the grinding wheel by shaking the wheel or other methods. (4) Read the scale on the measuring cylinder again. (5) The absolute value V of the difference between the scale marks on the measuring cylinder before and after inserting the grinding wheel diff Calculate. Equation (6) (V1=V0-V diff ) to calculate V1.

[0052] (Shape of the grindstone) The size and shape of the grinding wheel of the present invention can be selected appropriately depending on the application. Examples of the shape of the grinding wheel of the present invention include a cylindrical shape, an approximately cylindrical shape, a conical shape, an approximately conical shape, a bullet shape, a composite shape of a cylindrical and a conical shape, a composite shape of a cylindrical and an approximately conical shape, and a spherical shape. The grinding wheel of the present invention is preferably used as a mounted grinding wheel.

[0053] (Method of manufacturing grindstones) The grinding wheel of the present invention can be produced, for example, by mixing raw materials using a mixer, spreading the mixture in a mold, and heating it in a press or an electric furnace. [Example]

[0054] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0055] [Production of the first composite abrasive] The following raw materials (a) to (c) were mixed using a mixer (KitchenAid stand mixer) and dispersed uniformly to obtain a mixture.

[0056] (a) Phenolic resin (1) (Sumitomo Bakelite Co., Ltd., SUMILITE RESIN (registered trademark) PR-940) 25 g (b) Phenolic resin (2) (Sumilite Resin (registered trademark) PR-217, manufactured by Sumitomo Bakelite Co., Ltd.) 10 g (c) Aluminum oxide abrasive grains (Nanko Ceramics Co., Ltd., Aluminum Oxide WA120) 100g

[0057] The mixture was passed through a wire mesh (a stainless steel sieve (openings 1 mm) manufactured by Sanpo Co., Ltd.) to obtain a granular mixture. The granular mixture was subjected to granulation processing for about 20 minutes using a granulator (Parts Feeder DMS-45C manufactured by Sinfonia Technology Co., Ltd.) to obtain a first composite abrasive grain precursor. The obtained first composite abrasive grain precursor was placed in an electric furnace and heated at 170° C. for 9 hours to obtain the first composite abrasive grain. The first composite abrasive grains thus obtained were classified using a stainless steel sieve (mesh openings: 2.0 mm, 1.0 mm, 0.5 mm) manufactured by Sanpo Co., Ltd., and the particle size distribution was as shown in Table 1.

[0058] [Table 1]

[0059] [Manufacturing the second composite abrasive] The following raw materials (d) to (h) were mixed using a mixer (KitchenAid stand mixer) and dispersed uniformly to obtain a mixture.

[0060] (d) 100 g of polyol (polyoxypropylene polyol) (Actocol T-3000, manufactured by Mitsui Chemicals SKC Polyurethanes, Inc.) (e) Polymeric MDI (polymethylene polyphenyl polyisocyanate) (Tosoh Corporation, Millionate MR-200) 25g (f) 10 g of aromatic amine (3,3'-dichloro-4,4'-diaminodiphenylmethane) (Iharacuamine MT, manufactured by Kumiai Chemical Industry Co., Ltd.) (g) 2000g of EPDM rubber particles (Kokubu Green Farm color rubber chips KG12 3010) (rubber hardness of 60 measured with a type A durometer conforming to JIS K6253-3) (h) Aluminum oxide abrasive grains (Nanko Ceramics Co., Ltd., Aluminum Oxide WA120) 1500g

[0061] The mixture was subjected to granulation processing for about 20 minutes using a granulator (Parts Feeder DMS-45C manufactured by Sinfonia Technology Co., Ltd.) to obtain a second composite abrasive grain precursor. The obtained second composite abrasive grain precursor was heated in an oven (Isuzu Manufacturing Co., Ltd., SHF-212AS) at 60° C. for about 30 minutes to obtain second composite abrasive grains. The composite abrasive grains obtained were classified using a stainless steel sieve (mesh openings: 3.0 mm, 2.0 mm, 1.0 mm) manufactured by Sanpo Co., Ltd., and the particle size distribution was as shown in Table 2.

[0062] [Table 2]

[0063] [Grinding stone manufacturing] (Comparative Example 1) A conventional elastic grinding wheel (Daiwa Rabin WA80 CM43, manufactured by Daiwa Chemical Industry Co., Ltd.) (cylindrical, 25 mm in diameter and 25 mm in height) was fixed to the tip of a shaft (Taiyo Seiko Co., Ltd., diameter 6 mm, length 60 mm, material S50C) to obtain a mounted grinding wheel.

[0064] (Examples 1 to 4, Comparative Example 2) The raw materials shown in Table 3 were mixed and uniformly dispersed using a mixer (KitchenAid stand mixer) to obtain a mixture. In Table 3, the polyol, polymeric MDI, and aromatic amine used were the same as those used in producing the second composite abrasive.

[0065] [Table 3]

[0066] The mixture was placed in a mold and heated at 100°C for approximately 60 minutes in an oven (Isuzu Manufacturing Co., Ltd. SHF-212AS) to obtain a cylindrical grinding wheel with a diameter of 25 mm and a height of 25 mm. The obtained grinding wheel was fixed to the tip of a shaft (Taiyo Seiko Co., Ltd., diameter 6 mm, length 60 mm, material S50C) to obtain a mounted grinding wheel.

[0067] The porosity of each of the obtained grinding wheels was measured by the method described above. Note that V0 was the volume of a cylinder with a diameter of 25 mm and a height of 25 mm. As a result of the measurement, the porosity of the grinding wheels of Examples 1 to 4 was 35% by volume, the porosity of the grinding wheel of Comparative Example 1 was 0% by volume, and the porosity of the grinding wheel of Comparative Example 2 was 10% by volume. The densities of the grinding wheels of Examples 1 to 4 and Comparative Examples 1 and 2 were 1.09, 1.03, 1.04, 0.99, 1.91, and 1.1 g / cm, respectively. 3 It was.

[0068] [Grinding test] (Test conditions) Grindstone: Shafted grindstone (manufactured as described above) Workpiece: 50mm x 50mm x 30mm SUS316 Grinding equipment: Nakanishi product name: Espert 500 Rotation speed: 15,000 revolutions per minute (rpm) Pressing angle: 15° Pressing load: approx. 4.9N (500gf) Processing method: On a 30mm x 50mm surface (machined surface), grinding was performed 26.5 times back and forth along a 30mm straight line parallel to the 50mm side, with the center being 5mm from one 50mm side and 25mm from the other 30mm side (grinding center position). Grinding time: 120 seconds Temperature measuring instrument: Anritsu Meter Co., Ltd. handheld thermometer HD-1000 Temperature measurement method: On a 30mm x 50mm surface that shares a common side with the surface to be processed, a hole perpendicular to the surface is drilled 10mm from the surface to be processed and 5mm from one of the 50mm sides (the side closer to the processing point), and the temperature measuring device is inserted and fixed into the hole so that the side temperature part is directly below the center position of the grinding.

[0069] (test) For each of the mounted grindstones of the Examples and Comparative Examples, the masses of the mounted grindstones and the workpieces before and after grinding were measured, and the results are shown in Table 4.

[0070] [Table 4]

[0071] Furthermore, in each of the examples and comparative examples, the change in the temperature of the workpiece relative to the grinding time was measured, and the results are shown in Table 5 and FIG.

[0072] [Table 5]

[0073] Furthermore, in each example and each comparative example, the surface roughness in the longitudinal direction at the processed portion (arithmetic mean roughness R a , root mean square roughness R q , maximum height R z ) were measured and the results are shown in Table 6.

[0074] [Table 6]

[0075] The results shown in Table 4 show that the grinding wheel of the present invention is comparable to or even superior to the grinding wheel (Comparative Example 2) containing only the second composite abrasive grain (abrasive grain in which abrasive grains are fixed to the surface of rubber particles) as the composite abrasive grain in terms of grinding ratio (amount of grinding / amount of grinding wheel wear).

[0076] 1, the grinding wheel of the present invention has extremely excellent heat dissipation properties compared to the conventional elastic grinding wheel (Comparative Example 1), and also has heat dissipation properties comparable to those of a grinding wheel (Comparative Example 2) that contains only the second composite abrasive grains (composite abrasive grains in which abrasive grains are fixed to the surfaces of rubber particles).

[0077] Furthermore, from the results shown in Table 6, it can be seen that the grinding stone of the present invention is less likely to form deep cutting marks on the workpiece compared to the conventional elastic grinding stone (Comparative Example 1). The degree of formation of deep cutting marks is measured by the arithmetic mean roughness R a than the root mean square roughness R q and maximum height R z It is thought that this will have a significant impact on the value of

[0078] In addition, the grinding wheel (Comparative Example 2) containing only the second composite abrasive grains (composite abrasive grains in which abrasive grains are fixed to the surfaces of rubber particles) as composite abrasive grains showed more abrasive grains falling off after grinding than the other grinding wheels. Therefore, there is concern that the grinding power of the grinding wheel of Comparative Example 2 will decrease from the second grinding onwards. [Industrial Applicability]

[0079] The grinding wheel of the present invention can be suitably used for grinding and polishing various types of workpieces such as aluminum, iron, stainless steel, and titanium.

Claims

1. A grinding wheel containing composite abrasive grains, The composite abrasive includes a first composite abrasive having first abrasive grains dispersed in a first bond; The composite abrasive grains are bonded to each other by another binder so as to have pores that open to the surface, the particle diameter of the first abrasive grains is 0.04 to 0.5 mm (however, the first abrasive grains having particle diameters outside this range may be contained in an amount of 10 mass % or less relative to the total amount of the first abrasive grains); the particle size of the first composite abrasive grains is 0.1 to 5 mm (however, the first composite abrasive grains having particle sizes outside this range may be contained in an amount of 15 mass % or less based on the total amount of the first composite abrasive grains); the first binder is a thermoplastic resin or a thermosetting resin; The other binder is a thermoplastic resin or a thermosetting resin. Whetstone.

2. The composite abrasive further includes a second composite abrasive having second abrasive grains selected independently of the first abrasive grains fixed to surfaces of rubber particles by a second binder selected independently of the first binder and the other binders, 2. The grinding wheel according to claim 1, wherein a mass ratio (B / (A+B)) of the content (B) of the second composite abrasive grains to a total amount (A+B) of the content (A) of the first composite abrasive grains and the content (B) of the second composite abrasive grains is 0.8 or less.

3. 3. The grindstone according to claim 2, wherein the second composite abrasive grains have a particle size of 0.1 to 5 mm.

4. 4. The grinding wheel according to claim 2, wherein the rubber particles have a rubber hardness of 30 or more as measured with a Type A durometer in accordance with JIS K6253-3, and a rubber hardness of 80 or less as measured with a Type D durometer in accordance with JIS K6253-3.

5. 5. The grindstone according to claim 1, wherein the porosity of the pores is 5 to 50% by volume.

6. A grinding wheel described in any one of claims 1 to 5, wherein the first binder contains a phenolic resin.

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