Resin bond grinding wheel for plane grinding

Abstract

To provide a resin bond grinding wheel for plane grinding which can obtain a lifetime of the grinding wheel and a grinding quality with less abrasion due to processing heat in high-speed grinding processing of a metal workpiece.SOLUTION: A grinding wheel 16 contains: granulation materials 22 densely granulated with no pores by setting abrasive grains 18 combined with a phenol resin (first thermosetting resin) 20 of a high heat resistance and a high elastic modulus, an epoxy resin (second thermosetting resin) 24, which combines the granulation materials 22, of a lower heat resistance and a lower elastic modulus than the phenol resin 20; and pores of 20.2 to 38.3 vol.% formed among the granulation materials 22. When a face of a metal workpiece 12 is ground at a high speed with a side face of the grinding wheel 16, while abrasion due to processing heat is suppressed, a lifetime of the grinding wheel 16 and a grinding quality of the metal workpiece 12 are obtained. Further, since even a resin bond grinding wheel has pores of 20.2 to 38.3 vol.% among the granulation materials 22, clogging is suppressed and a preferable grinding wheel lifetime and sharpness can be obtained.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a resin-bonded grinding wheel for surface grinding, in which abrasive grains are bonded with a resin binder (resin bond). [Background technology]

[0002] In high-speed surface grinding using the side of the grinding wheel, such as double-disc surface grinding, the contact area with multiple metal workpieces, such as bearing parts, is large, so processing heat is likely to be generated. To perform highly efficient surface grinding of such metal workpieces, the grinding wheel must be elastic, and grinding wheels using elastic epoxy resin as a resin binder are used, but this poses the problem of being easily worn out by processing heat.

[0003] Grinding wheels that use phenolic resin, which has a high elastic modulus and is more heat resistant than epoxy resin, as a resin binder can suppress wear caused by processing heat, but they have weak elasticity, and in high-efficiency surface grinding processes, impacts on the grinding wheel or metal workpiece can cause damage to the grinding wheel and poor grinding quality of the workpiece, so they are not suitable for high-efficiency grinding processes.

[0004] In response to this, Patent Document 1 proposes a resin-bonded grinding wheel in which a large number of granules (grains) are formed by bonding abrasive grains together using epoxy resin, a thermosetting resin, and then bonded together using phenolic resin, a thermosetting resin with less elasticity than epoxy resin. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4777708 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when attempting to perform highly efficient surface grinding with the resin-bonded grinding wheel of Patent Document 1, the abrasive grains in the granules are bonded with an elastic epoxy resin, and the granules are worn away by processing heat, causing the abrasive grains to easily fall off, resulting in insufficient grinding efficiency.On the other hand, because a phenolic resin with a high elastic modulus is used as the resin binder for the granules, impacts on the grinding wheel or workpiece can sometimes cause the wheel to break or result in poor grinding quality for the workpiece.

[0007] The present invention has been made against the background of the above circumstances, and its object is to provide a resin-bonded grinding wheel for surface grinding that has little wear due to processing heat when using the side surface of the grinding wheel to perform high-speed surface grinding of metal workpieces, and that extends the life of the grinding wheel and provides good grinding quality.

[0008] With the above circumstances as a background, the inventors of the present invention have conducted extensive research into high-speed surface grinding of metal workpieces using the side surface of a grinding wheel, and have found that, contrary to the grinding wheel described in Patent Document 1, a resin-bonded grinding wheel is made by bonding a large number of granules (composed of abrasive grains bonded together using phenolic resin, a thermosetting resin, and then bonding these granules together using epoxy resin, a thermosetting resin that is more elastic than phenolic resin. This results in less wear due to processing heat, and ensures long grinding wheel life and grinding quality when grinding the surfaces of metal workpieces at high efficiency for mass production. The present invention was made based on this finding. [Means for solving the problem]

[0009] In other words, the gist of the first invention is (1) a resin-bonded grinding wheel for surface grinding that uses the side of the wheel to grind the surface of a metal workpiece, (2) granules formed by bonding abrasive grains with a first thermosetting resin having a high elastic modulus, (3) a second thermosetting resin having a lower elastic modulus than the first thermosetting resin that bonds the granules together, and (4) pores of 20.2 to 38.3 volume % formed between the granules.

[0010] The gist of the second invention is that in the first invention, the first thermosetting resin is a phenol resin and the second thermosetting resin is an epoxy resin.

[0011] The gist of the third invention is that, in the second invention, the resin-bonded grinding wheel for surface grinding contains the granules and the second thermosetting resin in a weight ratio ranging from 3.07:1 to 6.81:1.

[0012] The gist of the fourth invention is that in any of the first to fourth inventions, the resin-bonded grinding wheel for surface grinding contains 63.4 to 73.3 wt% of the abrasive grains, 12.0 to 13.9 wt% of the first thermosetting resin, and 12.8 to 24.6 wt% of the second thermosetting resin. [Effects of the Invention]

[0013] According to a first invention, the resin-bonded grinding wheel for surface grinding is (1) a resin-bonded grinding wheel for surface grinding of a metal workpiece with the side surface of the wheel, and includes (2) granules formed by granulating abrasive grains bound together with a first thermosetting resin having a high elastic modulus, (3) a second thermosetting resin having a lower elastic modulus than the first thermosetting resin and binding the granules together, and (4) pores of 20.2 to 38.3 volume % formed between the granules. As a result, because the abrasive grains in the granules are bound together with the first thermosetting resin having a low elasticity, wear due to processing heat is suppressed, and at the same time, because the granules are bound together with the second thermosetting resin having a low elastic modulus, wear due to processing heat is reduced when the side surface of the wheel is used to grind the surface of a metal workpiece with high efficiency, resulting in long wheel life and improved grinding quality. Furthermore, even resin-bonded grinding wheels have pores of 20.2 to 38.3% by volume, which prevents clogging and provides suitable wheel life and sharpness.

[0014] According to the resin-bonded grinding wheel for surface grinding of the second invention, the first thermosetting resin is a phenolic resin and the second thermosetting resin is an epoxy resin. As a result, the resin-bonded grinding wheel for surface grinding contains granules formed by binding abrasive grains with a phenolic resin having a high elastic modulus, and an epoxy resin having a lower elastic modulus than the phenolic resin that binds the granules. Therefore, when the surface of a metal workpiece is ground with high efficiency using the side surface of the grinding wheel, wear due to processing heat is reduced, and the life of the grinding wheel and grinding quality are improved.

[0015] According to the third aspect of the present invention, the resin-bonded grinding wheel for surface grinding contains granules and epoxy resin in a weight ratio ranging from 3.1:1 to 6.8:1. This reduces wear due to processing heat when the side surface of the grinding wheel is used to grind a metal workpiece surface with high efficiency, thereby extending the life of the grinding wheel and improving grinding quality.

[0016] The resin-bonded grinding wheel for surface grinding of the fourth invention contains 63.4 to 73.3 wt% abrasive grains, 12.0 to 13.9 wt% first thermosetting resin, and 12.8 to 24.6 wt% second thermosetting resin. This reduces wear due to processing heat when grinding a metal workpiece surface with high efficiency using the side surface of the grinding wheel, thereby extending the life of the grinding wheel and improving grinding quality. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a plan view conceptually illustrating the configuration of a surface grinding device to which a resin-bonded grinding wheel for surface grinding according to an embodiment of the present invention is applied. [Figure 2] 2 is an enlarged schematic diagram illustrating the structure of the resin-bonded grinding wheel for surface grinding in FIG. 1. FIG. [Figure 3] 2 is an optical microscope photograph showing an enlarged view of the surface of the resin-bonded grinding wheel for surface grinding shown in FIG. 1. [Figure 4] 1 is a table showing the composition of samples for each bond strength used in grinding tests of resin-bonded grinding wheels for surface grinding conducted by the present inventors. [Figure 5] 5 is a bar graph showing the composition of the samples at each level in FIG. 4 in volume %. [Figure 6]5 is a table showing the physical properties and grinding test results of the samples for each level in FIG. 4. [Figure 7] 5 is a bar graph showing the bending strength of the samples for each level in FIG. 4. [Figure 8] 5 is a bar graph showing the elastic modulus of the samples at each level in FIG. 4. DETAILED DESCRIPTION OF THE INVENTION

[0018] An application example of the present invention will be described in detail below with reference to the drawings. Note that in the following embodiment, the drawings are appropriately simplified or modified, and the dimensional ratios and shapes of the various parts are not necessarily drawn accurately. [Example]

[0019] 1 is a schematic plan view of a rotary surface grinding machine 10 that uses a resin-bonded grinding wheel for surface grinding (hereinafter referred to as the grinding wheel) 16 of this embodiment. The surface grinding machine 10 is used to highly efficiently grind the surface (flat end face) of a metal workpiece 12, such as a bearing part. The surface grinding machine 10 is equipped with a rotary table 14 that rotates a plurality of metal workpieces 12 about a first central axis of rotation C1 while positioning them at regular circumferential intervals on a center line (300 mmφ) CL of a diameter D1 of the rotary table 14, for example, approximately 600 mmφ.

[0020] The grinding wheel 16 is ring-shaped with a flat, annular grinding wheel side surface, is supported by the surface grinding machine 10 so that the grinding surface is parallel to the upper surface of the rotary table 14, and is rotated about a second rotational center axis C2 parallel to the first rotational center axis C1. The diameter D2 of the grinding wheel 16 is approximately half the diameter D1 of the rotary table 14, for example, 355 mmφ. Four metal workpieces 12 positioned on the center line CL are arranged inside the grinding wheel 16, and when the fourth metal workpiece 12 is ground at the entrance side, the first metal workpiece 12 is ground at the exit side. The metal workpieces 12 are, for example, 50 mmφ x 15 mmt x 35 mmφ and are arranged at intervals of approximately 20 mm.

[0021] As shown in the schematic diagram of Figure 2, the grinding wheel 16 includes a plurality of granules 22 formed by bonding abrasive grains 18 together with a first thermosetting resin, such as a phenolic resin 20, which has high heat resistance and a high elastic modulus, resulting in dense granules without pores. The granules 22 are bonded together with a second thermosetting resin, such as an epoxy resin 24, which has a lower elastic modulus than the phenolic resin 20. The granules 22 are then bonded together with pores 26 formed between the granules 22. The grinding wheel 16 contains 60 to 75 wt% of abrasive grains 18, for example, #46 to #150, and is made of one or more materials selected from alumina, zirconia, silicon carbide, titania, manganese compounds, barium carbonate, chromium oxide, iron oxide, CBN, and diamond. Figure 3 is an optical microscope photograph showing an enlarged view of the surface of the grinding wheel 16.

[0022] The grinding wheel 16 contains 75 to 88 wt% of granules 22, and the weight ratio of the granules 22 to the epoxy resin 24 is preferably in the range of 3.1:1 to 6.8:1. The grinding wheel 16 also preferably contains 63.4 to 73.3 wt% of abrasive grains 18, 12.0 to 13.9 wt% of phenolic resin 20, 12.8 to 24.6 wt% of epoxy resin 24, and 20.2 to 38.3 vol% of pores 26 formed between the granules 22.

[0023] The grinding wheel 16 is manufactured, for example, by the following manufacturing method. First, in the granulation step, for example, liquid phenolic resin 20 is added to abrasive grains 18 to granulate them, and then the mixture is dried to produce granules 22. Next, in the molding step, a material obtained by kneading the granules 22 and epoxy resin 24 is used to produce a green body by slip casting. Then, in the firing step, the green body is fired to obtain the grinding wheel 16 shown in FIG. 1.

[0024] (Grinding test) Next, the grinding tests conducted by the present inventors will be described. First, test pieces of levels 1 to 6 were prepared using the compositions shown in Figure 4, and grinding tests were conducted on each of them under the grinding test conditions shown below.

[0025] Figure 5 shows the composition (volume %) of each test sample in a bar graph. The volume of the granules 22 contained in each test sample (volume VG of abrasive grains 18 + volume VB1 of phenolic resin 20) is approximately constant, and the volume VG of the abrasive grains 18 varies depending on the volume VB2 of the epoxy resin 24. Figure 6 shows the measurements of the bending strength, elastic modulus, porosity, grinding wheel life, and sharpness of each test sample, as well as the evaluation results of these measurements. The measurements and evaluations were performed using the measurement and evaluation methods described below. Figure 7 is a bar graph showing the bending strength (MPa) of each test sample, and Figure 8 is a bar graph showing the elastic modulus (GPa) of each test sample.

[0026] (Grinding test conditions) Machine: Sanshin Seiki Co., Ltd. fully automatic rotary surface grinder SPG-600 Grindstone dimensions: 355mmφ×40mmt×245mmφ Grinding surface 10mmW, 108cm 2 Workpiece dimensions: Ring shape 50mmφ×35mmφ Area 40cm 2 / 4 pieces Work material: S45C (tempered steel) Grinding wheel rotation speed: 900 rpm (1003 / min) Cutting speed: 0.3mm / min Table rotation speed: 8 rpm Total cutting depth (N=1): 4mm (40cm 2 ×0.4cm=16cm 3 / 4 pieces) Grinding efficiency: 1.2cm 3 / min Grinding fluid: NK-Z (50 times diluted) manufactured by Noritake Co., Ltd. 8L / min

[0027] (Method for measuring and evaluating bending strength) Measuring equipment: Shimadzu Corporation AG-50kNG three-point bending tester Measurement method: A load is applied to the center of the test piece supported at two points 100 mm apart, and the load at which it breaks is measured. Test piece: 120mmL x 15mmT x 30mmW Evaluation method: Those whose obtained bending load value (MPa) exceeded the first judgment value of 20 MPa, which was predetermined from the practical viewpoint of surface grinding, were evaluated with a ◎ mark; those between the first judgment value of 20 MPa and the lower second judgment value of 15 MPa were evaluated with a ○ mark; those between the second judgment value of 15 MPa and the lower third judgment value of 10 MPa were evaluated with a △ mark; and those below the third judgment value of 10 MPa were evaluated as not suitable for practical use and were evaluated with an × mark.

[0028] (Method for measuring and evaluating elastic modulus) Measuring equipment: Shimadzu Corporation AG-50kNG three-point bending tester Measurement method: While applying stress to the test piece, the elastic deformation is continuously measured, and the (flexural) elastic modulus (elastic coefficient) is calculated from the relationship between stress and elastic deformation. Test piece: 120mmL x 15mmT x 30mmW Evaluation method: Those with an obtained elastic modulus (GPa) below the first judgment value of 2 GPa, which was established from a practical viewpoint for surface grinding, were evaluated with a ◎ mark; those between the first judgment value of 2 GPa and the higher second judgment value of 3 GPa were evaluated with a ○ mark; those between the second judgment value of 3 GPa and the higher third judgment value of 4 GPa were evaluated with a △ mark; and those exceeding the third judgment value of 4 GPa were evaluated as being unsuitable for practical use and were evaluated with an × mark.

[0029] (Method for measuring and evaluating porosity) Measurement method: The porosity (volume %) of the test piece was calculated from the specific gravity of the test piece and the specific gravity of the raw material. Test piece: 120mmL x 15mmT x 30mmW

[0030] (Method for measuring and evaluating grinding wheel life) Grinding wheel life measurement method: Grinding test machine Evaluation method for grinding wheel life: Evaluation was based on the amount of wear of the grinding wheel during the grinding test. Wear resistance of over 1.6 times that of conventional grinding wheels bonded only with epoxy resin was evaluated as ◎, 1.2 to 1.6 times as good ...

[0031] (Method for measuring and evaluating sharpness) Sharpness measurement method: Grinding test machine Sharpness evaluation method: Evaluation was based on the power consumption of the grinding wheel rotation axis during the grinding test. Power consumption less than 0.8 times that of conventional grinding wheels bonded only with epoxy resin was evaluated as ◎, 0.8 to 1.0 times as much as ○, 1.0 to 1.2 times as much as △, and more than 1.2 times as much as ×.

[0032] 6, the grinding wheel performance evaluation revealed that, among the test samples with different resin amounts, test samples of levels 2, 3, 4, and 5 received high evaluations for grinding wheel life and sharpness. Based on these evaluation results, grinding wheels 16 are preferably of levels 2 to 5, contain granules 22 at a ratio of 75 to 88 wt%, and the granules 22 and epoxy resin 24 are preferably contained in a weight ratio ranging from 3.1:1 to 6.8:1. Furthermore, grinding wheels 16 preferably contain abrasive grains 18 at 63.4 to 73.3 wt%, phenolic resin 20 at 12.0 to 13.9 wt%, epoxy resin 24 at 12.8 to 24.6 wt%, and pores 26 at 20.2 to 38.3 volume%.

[0033] As described above, the grinding wheel (resin-bonded grinding wheel for surface grinding) 16 of this embodiment is a grinding wheel 16 for surface grinding the surface of a metal workpiece 12 with its side surface, and includes granules 22 formed by binding abrasive grains 18 with a phenolic resin (first thermosetting resin) 20 that has high heat resistance and a high modulus of elasticity, thereby forming dense granules without pores, and an epoxy resin (second thermosetting resin) 24 that has a lower heat resistance and a lower modulus of elasticity than the phenolic resin 20 and binds the granules 22. As a result, according to the grinding wheel 16 of this embodiment, since the granules 22 are formed by binding the abrasive grains 18 with the phenolic resin 20, which has low elasticity, wear due to processing heat is suppressed, and at the same time, since the granules 22 are bound with the epoxy resin 24, when the surface of the metal workpiece 12 is ground with high efficiency with the side surface of the grinding wheel 16, wear due to processing heat is reduced, thereby extending the life of the grinding wheel 16 and improving the grinding quality of the metal workpiece 12. Furthermore, the grinding wheel 16 of this embodiment, even though it is a resin-bonded grinding wheel, has 20.2 to 38.3 volume % of pores 26 between the granules 22, so clogging is suppressed and a suitable grinding wheel life and sharpness are obtained.

[0034] The grinding wheel (resin-bonded grinding wheel for surface grinding) 16 of this embodiment contains granules 22 and epoxy resin (second thermosetting resin) 24 in a weight ratio ranging from 3.1:1 to 6.8:1. As a result, when the side surface of the grinding wheel 16 is used to grind the surface of the metal workpiece 12 with high efficiency, wear due to processing heat is reduced, and the life of the grinding wheel 16 and grinding quality of the metal workpiece 12 are improved.

[0035] The grinding wheel (resin bond grinding wheel for surface grinding) 16 of this embodiment contains 63.4 to 73.3 wt% abrasive grains 18, 12.0 to 13.9 wt% phenolic resin (first thermosetting resin) 20, and 12.8 to 24.6 wt% epoxy resin (second thermosetting resin) 24. As a result, when the side surface of the grinding wheel 16 is used to grind the surface of a metal workpiece 12 with high efficiency, wear due to processing heat is reduced, and the life of the grinding wheel 16 and grinding quality of the metal workpiece 12 are improved.

[0036] Although one embodiment of the present invention has been described above, the present invention can also be applied in other aspects.

[0037] For example, in the above-described embodiment, the granules 22 contained in the grinding wheel 16 are depicted as being spherical in FIG. 2, but may be of other shapes such as elliptical or cylindrical.

[0038] In addition, in the grinding wheel 16 of the above-described embodiment, the phenolic resin 20 is used as the first thermosetting resin having high heat resistance and high elastic modulus, and the epoxy resin 24 is used as the second thermosetting resin having relatively lower heat resistance and lower elastic modulus than the first thermosetting resin. However, a resin other than the phenolic resin 20 may be used as the first thermosetting resin, and a resin other than the epoxy resin 24 may be used as the second thermosetting resin.

[0039] In the above-described embodiment, the grinding wheel 16 is used in the rotary surface grinder 10, but it can also be applied to a double-sided grinder that grinds both sides of the metal workpiece 12 simultaneously.

[0040] Although not specifically exemplified, the present invention can be used with various modifications within the scope of the invention. [Explanation of symbols]

[0041] 12: Metal workpiece 14: Rotating table 16: Grinding wheel (resin bond grinding wheel for surface grinding) 18: Abrasive grain 20: Phenolic resin (first thermosetting resin) 22: Granules 24: Epoxy resin (second thermosetting resin) 26: Stoma

Claims

1. A resin bond grinding wheel for surface grinding that grinds the surface of a metal workpiece with the side surface of the grinding wheel, a granulated body in which abrasive grains are bound together with a first thermosetting resin having a high elastic modulus; a second thermosetting resin having a lower elastic modulus than the first thermosetting resin, which bonds the granules together; and 20.2 to 38.3% by volume of pores formed between the granules. A resin bonded grinding wheel for surface grinding characterized by the above.

2. the first thermosetting resin is a phenolic resin; The second thermosetting resin is an epoxy resin.

2. The resin bonded grinding wheel for surface grinding according to claim 1.

3. The resin-bonded grinding wheel for surface grinding contains the granules and the second thermosetting resin in a weight ratio ranging from 3.07:1 to 6.81:

1.

3. The resin bonded grinding wheel for surface grinding according to claim 2.

4. The resin bonded grinding wheel for surface grinding contains 63.4 to 73.3 wt % of the abrasive grains, 12.0 to 13.9 wt % of the first thermosetting resin, and 12.8 to 24.6 wt % of the second thermosetting resin.

5. The resin bonded grinding wheel for surface grinding according to claim 1, wherein the resin bonded grinding wheel is a carbide or carbide alloy.

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