Superabrasive cutting wheel

Abstract

Provided is a superabrasive cutting wheel comprising: a disk-shaped base metal made of cemented carbide; and a superabrasive layer provided on the outer peripheral part of the base metal. The superabrasive layer includes a superabrasive, a metal bond, and a filler. The difference between the coefficient of linear expansion of the superabrasive layer and the coefficient of linear expansion of the base metal is 0-15.0 × 10-6 (1 / °C) or less.

Description

Super abrasive cut-off wheel

[0001] The present disclosure relates to a superabrasive cut-off wheel. This application claims priority to Japanese Patent Application No. 2024-119405, filed on July 25, 2024. The entire contents of said Japanese Patent Application are incorporated herein by reference.

[0002] Conventionally, superabrasive cutting wheels have been disclosed, for example, in Japanese Patent Laid-Open No. 9-174441 (Patent Document 1), Japanese Patent Laid-Open No. 2009-172751 (Patent Document 2), and Japanese Patent Laid-Open No. 2013-82072 (Patent Document 3).

[0003] Japanese Patent Laid-Open No. 9-174441 Japanese Patent Laid-Open No. 2009-172751 Japanese Patent Laid-Open No. 2013-82072

[0004] The superabrasive cut-off wheel of the present disclosure includes a disk-shaped base metal made of cemented carbide and a superabrasive layer provided on the outer periphery of the base metal. The superabrasive layer includes superabrasive grains, a metal bond, and a filler. The difference between the linear expansion coefficient of the superabrasive layer 120 and the linear expansion coefficient of the base metal 110 is 0 to 15.0 × 10 －６ (1 / °C) or less.

[0005] Fig. 1 is a front view of a superabrasive cut-off wheel 100 according to an embodiment. Fig. 2 is a cross-sectional view of the superabrasive cut-off wheel 100 taken along the line II-II in Fig. 1.

[0006] [Problem to be Solved by the Present Disclosure] Conventional superabrasive cut-off wheels have the problem of low cutting accuracy.

[0007] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described.

[0008] Difficult-to-cut materials are cut with a cut-off wheel that has a base metal made of cemented carbide and a peripheral cutting edge (super abrasive grain layer) made of resin-bonded super abrasive grain. To reduce the cutting allowance, a thin wheel (1mm or less) is required. In this case, if the base metal has a low modulus of longitudinal elasticity, deformation such as undulation occurs during processing, resulting in a loss of dimensional accuracy. Therefore, dimensional accuracy is maintained by using a base metal made of cemented carbide.

[0009] To reduce the cutting allowance, there is a demand for a thinner superabrasive layer, specifically 0.4 mm or less.

[0010] When the thickness is reduced, deformation such as undulations is more likely to occur during processing. To prevent this, it is necessary to improve the modulus of longitudinal elasticity of the superabrasive layer to suppress vibrations.

[0011] One possible solution is to change the abrasive layer from a resin bond to a metal bond in order to improve the modulus of longitudinal elasticity.

[0012] On the other hand, since such cut-off wheels need to be thin and capable of being machined with high precision, the superabrasive grain layer that forms the outer cutting edge is continuous in the circumferential direction and is not segmented.

[0013] In the manufacture of cut-off wheels, the cemented carbide base metal and the superabrasive grain layer are bonded together at the same time as the superabrasive grain layer is sintered.

[0014] In cut-off wheels manufactured in this manner, the difference in expansion coefficient between the carbide base metal and the metal bond makes it easy for the carbide base metal to warp during product manufacturing, and this tendency becomes more pronounced if the thickness of the base metal is made thinner.

[0015] (Explanation of the configuration using drawings) Fig. 1 is a front view of a superabrasive cut-off wheel 100 according to an embodiment. Fig. 2 is a cross-sectional view of the superabrasive cut-off wheel 100 taken along the line II-II in Fig. 1.

[0016] The superabrasive cut-off wheel 100 of the present disclosure includes a disk-shaped base metal 110 made of cemented carbide, and a superabrasive layer 120 provided on an outer periphery 112 of the base metal 110 .

[0017] The superabrasive layer 120 includes superabrasive grains, a metal bond, and a filler. The difference between the linear expansion coefficient of the superabrasive layer 120 and the linear expansion coefficient of the base metal 110 is 0 to 15.0×10 －６ (1 / °C) or less.

[0018] In the superabrasive cut-off wheel 100 configured in this manner, the superabrasive layer 120 contains a filler, which increases the Young's modulus of the superabrasive layer 120 and improves cutting accuracy.

[0019] The linear expansion coefficient can be measured by, for example, thermomechanical analysis (TMA). In the superabrasive cut-off wheel 100 configured in this manner, the difference in the linear expansion coefficient between the base metal 110 and the superabrasive layer 120 is small, so that thermal distortion can be alleviated.

[0020] As a result, cutting accuracy is improved. More specifically, warping of the cemented carbide that constitutes the base metal 110 can be prevented. This prevents waviness of the base metal 110, and provides the superabrasive cut-off wheel 100 that allows for processing with reduced waviness.

[0021] More preferably, the difference between the linear expansion coefficient of the superabrasive layer 120 and the linear expansion coefficient of the base metal 110 is 0 to 8.0 × 10 －６ (1 / °C) or less.

[0022] Preferably, the metal bond contains at least one selected from the group consisting of copper (Cu), iron (Fe), tin (Sn), nickel (Ni), zinc (Zn), aluminum (Al), titanium (Ti), silver (Ag), and cobalt (Co).

[0023] Preferably, the filler comprises at least one selected from the group consisting of alumina, silicon carbide, zirconia, diamond, cBN, graphite, and hBN.

[0024] Preferably, the Young's modulus of the superabrasive layer 120 is 300 MPa or more. Preferably, the superabrasive layer 120 is a sintered body. In this case, the superabrasive layer 120 has a high Young's modulus, and the cutting accuracy of the superabrasive cut-off wheel 100 is improved.

[0025] As the superabrasive grains, diamond grains, cBN (cubic boron nitride) grains, or a mixture thereof can be used.

[0026] The cemented carbide is made by sintering tungsten carbide (WC) powder with cobalt (Co) as a binder metal at high temperature. Titanium carbide (TiC), tantalum carbide (TaC), etc. may also be added.

[0027] The workpiece to be cut by the superabrasive cut-off wheel 100 is, for example, a brittle body, such as glass, a magnet, or a ceramic.

[0028] Outer periphery 112 and superabrasive layer 120 may be in direct contact with each other, or may not be in direct contact with each other but may have some kind of layer interposed therebetween. When an intervening layer is used, it is preferable that the layer be one that adheres closely to both outer periphery 112 and superabrasive layer 120. Examples of such an intervening layer include copper and nickel.

[0029] The base metal 110 has a main body portion 111 and an outer periphery portion 112 located outside the main body portion 111. The main body portion 111 and the outer periphery portion 112 may have the same chemical composition or different chemical compositions.

[0030] The superabrasive cut-off wheel 100 can rotate in the direction indicated by the arrow 101. The thickness of the base metal 110 in the axial direction (the direction perpendicular to the direction of rotation) is, for example, 1 mm or less, and preferably 0.4 mm or less. The superabrasive layer 120 is annular.

[0031] For example, a neodymium magnet is cut under the conditions of a circumferential speed of 50 m / sec and a feed rate of 200 mm / min, with the diameter of the superabrasive cut-off wheel 100 being 100 mm, the radial thickness x of the superabrasive layer 120 being 3 mm, and the diameter of the holes 130 being 40 mm. The cutting accuracy can be evaluated by checking the width of the cut groove.

[0032] (Method of Manufacturing Superabrasive Cut-Off Wheel 100) An example of a method of manufacturing the superabrasive cut-off wheel 100 will be described. In manufacturing the superabrasive cut-off wheel 100, first, the thickness of the base metal 110 is machined. The inner and outer diameters of the base metal 110 are machined.

[0033] The base metal 110 is immersed for 10 to 20 minutes in a strong alkali solution having a liquid temperature of 60 to 80° C. and a pH of 14 or higher, thereby removing oil from the surface of the base metal 110 (degreasing treatment).

[0034] The base metal 110 is washed with pure water and ultrasonic waves for 2 to 5 minutes, and then immersed in concentrated hydrochloric acid at room temperature adjusted to a pH of 2 to 3 for 3 minutes, thereby removing rust and surface oxide films from the base metal 110 (acid treatment).

[0035] A nickel plating of 5 μm or less is formed on the surface (radial surface) of the base metal 110. The base metal 110 is immersed in a strong alkaline solution with a liquid temperature of 60-80°C and a pH of 14 or higher for 10-20 minutes. This removes oil from the surface of the base metal 110. (Degreasing treatment) The base metal 110 is immersed in concentrated hydrochloric acid at room temperature adjusted to a pH of 2-3 for 3 minutes. This removes rust and surface oxide film from the base metal 110. (Acid treatment) The base metal 110 is washed with pure water and ultrasound for 2-5 minutes.

[0036] A cyanide copper plating is formed on the nickel plating to a thickness of 5 μm or less. A superabrasive layer 120 is formed on the cyanide copper plating. Methods for forming the superabrasive layer 120 include placing the cyanide copper plated base metal 110 in a mold, filling the mold near the outer periphery of the base metal 110 with a mixed powder of metal bond and diamond abrasive grains, cold molding the base metal 110 in the mold to form the superabrasive layer 120, and then sintering the superabrasive layer 120 and the base metal 110 together in the mold.

[0037] When sintering the superabrasive layer 120, the superabrasive layer 120 is sintered and simultaneously fixed to the base metal 110. At this time, since the difference in the linear expansion coefficient between the superabrasive layer 120 and the cemented carbide is small, the stress (thermal stress) in the superabrasive layer 120 and the base metal 110 is small even when cooled to room temperature after sintering. Therefore, warping of the superabrasive layer 120 and the base metal 110 can be prevented. Furthermore, cracking of the superabrasive layer 120 can be prevented.

[0038] EXAMPLES Samples 1 to 7 were fabricated as superabrasive cut-off wheels 100 (shapes shown in FIGS. 1 and 2) having base metals 110 and superabrasive grain layers 120 shown in Table 1.

[0039]

[0040] The base metal 110 was a cemented carbide. The proportion of Co in the cemented carbide is shown in Table 1, with the remainder being WC and unavoidable impurities. These compositions were confirmed by energy dispersive X-ray spectroscopy (EDX).

[0041] The components of the superabrasive layer 120 were two main bond components, superabrasive grains, and a filler, and contained these in the proportions shown in Table 1.

[0042] The diameter D of base metal 110 was 100 mm, the thickness t1 of base metal 110 was 0.35 mm, the height X of superabrasive layer 120 was 3 mm, and the thickness t2 of superabrasive layer 120 was 0.4 mm.

[0043] "Linear expansion coefficient" indicates the average linear expansion coefficient from room temperature to 100° C. "Linear expansion coefficient difference" indicates the absolute value of the difference between the linear expansion coefficient of base metal 110 and the linear expansion coefficient of superabrasive layer 120. These linear expansion coefficients were confirmed by thermomechanical analysis (TMA).

[0044] The properties of each material are shown in Table 2.

[0045]

[0046] The waviness of the superabrasive grain layer 120 was measured for sample numbers 1 to 7. The results are shown in Table 3.

[0047]

[0048] Specifically, the waviness of the superabrasive layer 120 was measured using a flatness measuring device. When the flatness (Sz maximum - minimum) was 5 μm or less, it was rated as "minor waviness," when the flatness was more than 5 μm and less than 10 μm, it was rated as "small waviness," when the flatness was more than 10 μm and less than 20 μm, it was rated as "medium waviness," and when the flatness was more than 20 μm, it was rated as "large waviness." For sample number 7, cracks that could be seen with the naked eye had occurred in the superabrasive layer 120.

[0049] The superabrasive cut-off wheels 100 of sample numbers 1 to 6 were used to cut workpieces (material: magnetic material). The cutting conditions were a peripheral speed of the superabrasive cut-off wheel 100 of 20 m / s, a depth of cut of 0.2 mm / pass, and feed rates of 100 mm / min, 50 mm / min, and 10 mm / min, and the straightness of the cut surface (deviation from a straight line at a 50 mm line of the cut surface, unit: μm) was evaluated. The evaluation was performed using a surface grinder. The results are shown in Table 3.

[0050] The number in the "Straightness" column indicates the straightness, and for example, "10 or less" indicates that the deviation of the actual cut surface was 10 μm or less for a straight line of 50 mm on the cut surface.

[0051] The difference between the linear expansion coefficient of the superabrasive layer 120 and the linear expansion coefficient of the base metal 110 is 0 to 15.0 × 10 －６ It was confirmed that a preferable result could be obtained if the temperature was (1 / °C) or less.

[0052] Under severe cutting conditions, such as high-speed cutting at a feed rate of 100 mm / min, the difference between the linear expansion coefficient of the superabrasive layer 120 and the linear expansion coefficient of the base metal 110 is 0 to 8.0 × 10 －６ It was confirmed that the straightness values ​​of samples 1 to 3, which were equal to or less than (1 / °C), were the best.

[0053] The embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the above-described embodiments, and is intended to include meanings equivalent to the claims and all modifications within the scope thereof.

[0054] 100 Superabrasive cutting wheel, 101 Arrow, 110 Base metal, 111 Main body, 112 Outer periphery, 120 Superabrasive layer, 130 Hole

Claims

1. A method for manufacturing a cutting tool comprising: a disk-shaped base metal made of cemented carbide; and a superabrasive layer provided on the outer periphery of the base metal, wherein the superabrasive layer contains superabrasive grains, a metal bond, and a filler; and the difference between the linear expansion coefficient of the superabrasive layer and the linear expansion coefficient of the base metal is 0 to 15.0 × 10 －６ (1 / °C) or less.

2. The difference between the linear expansion coefficient of the superabrasive layer and the linear expansion coefficient of the base metal is 0 to 8 x 10 －６ 2. The superabrasive cut-off wheel of claim 1, wherein the curvature of the cut-off wheel is less than 1 / °C.

3. The superabrasive cut-off wheel according to claim 1 or 2, wherein the metal bond contains at least one selected from the group consisting of copper (Cu), iron (Fe), tin (Sn), nickel (Ni), zinc (Zn), aluminum (Al), titanium (Ti), silver (Ag), and cobalt (Co).

4. The superabrasive cut-off wheel according to claim 1 or 2, wherein the filler comprises at least one selected from the group consisting of alumina, silicon carbide, zirconia, diamond, cBN, graphite, and hBN.

5. The superabrasive cut-off wheel according to claim 1 or 2, wherein the superabrasive layer has a Young's modulus of 300 MPa or more.

6. The superabrasive cut-off wheel according to claim 1 or 2, wherein the superabrasive layer is a sintered body.

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