Superabrasive cutting wheel

Abstract

Provided is a superabrasive cutting wheel comprising: a disk-shaped base metal made of cemented carbide and having a body part and an outer peripheral part provided on an outer periphery of the body part; and a superabrasive layer provided on an outer peripheral part of the base metal. The superabrasive layer includes a superabrasive and a metal bond. In the outer peripheral part, the concentration of cobalt is lower than in the body part.

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. 2024-119403, filed on July 25, 2024. The entire contents of said Japanese Patent Application are incorporated herein by reference.

[0002] Conventionally, superabrasive cutting wheels are disclosed in, for example, 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 cutting wheel of the present disclosure comprises a disk-shaped base metal made of cemented carbide having a main body portion and an outer periphery portion provided on the outer periphery of the main body portion, and a superabrasive layer provided on the outer periphery of the base metal, the superabrasive layer containing superabrasive grains and a metal bond, and the outer periphery portion has a lower cobalt concentration than the main body portion.

[0005] Fig. 1 is a front view of a superabrasive cut-off wheel 100 according to an embodiment. Fig. 2 is a front view of the superabrasive cut-off wheel 100 used to measure the bonding strength between a base metal 110 and a superabrasive layer 120. Fig. 3 is a cross-sectional view of the superabrasive cut-off wheel taken along the line indicated by the arrow III-III in Fig. 2.

[0006] [Problem to be Solved by the Present Disclosure] Conventional superabrasive wheels have had the problem of weak bonding strength between the base metal and the superabrasive layer.

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

[0008] When cutting materials such as metals or plastics, a cut-off wheel is used, which has an abrasive layer made of abrasive grains such as diamonds bonded with a binder on the outer periphery of a disk-shaped base metal.

[0009] In this type of cutting, in order to reduce waste of the workpiece, the cutting allowance must be made small, and a thin wheel (1 mm or less) is required.

[0010] If the thickness of the wheel is reduced, the thickness of the base metal also becomes thinner, which results in a decrease in rigidity, which causes deformation such as undulation during cutting, and a loss of dimensional accuracy.

[0011] As a countermeasure to this problem, there are cut-off wheels that use cemented carbide as the base material and can maintain dimensional accuracy, the contents of which are disclosed in Patent Documents 1 to 3.

[0012] Even with cut-off wheels that use carbide as the base metal as described above, users are requesting thinner cut-off wheels to reduce the cutting allowance.

[0013] To further reduce the thickness, it is difficult to solve the problem by simply improving the modulus of longitudinal elasticity of the base metal; it is necessary to improve the modulus of longitudinal elasticity of the abrasive grain layer more than is currently the case and suppress vibration.

[0014] As a countermeasure, the abrasive layer is changed from a resin bond to a metal bond in order to improve the modulus of longitudinal elasticity.

[0015] However, it is difficult to ensure the bonding strength between the cemented carbide base metal and the abrasive grain layer, and the bonding strength is very weak when the conventional method of simultaneously sintering the base metal and the abrasive grain layer is used.

[0016] (Description of Configuration Using Drawings) FIG. 1 is a front view of a superabrasive cut-off wheel 100 according to an embodiment.

[0017] The superabrasive cut-off wheel 100 of the present disclosure includes a disk-shaped base metal 110 made of cemented carbide having a main body portion 111 and an outer periphery portion 112 provided on the outer periphery of the main body portion 111, and a superabrasive layer 120 provided on the outer periphery portion 112 of the base metal 110. The superabrasive layer 120 includes superabrasive grains and a metal bond, and the outer periphery portion 112 has a lower cobalt concentration than the main body portion 111. Holes 130 are formed in the base metal 110.

[0018] In the superabrasive cut-off wheel 100 configured in this manner, the concentration of cobalt is lower in the outer periphery 112 than in the main body 111. Therefore, the metal bond of the superabrasive layer 120 and the outer periphery 112 are firmly bonded together.

[0019] More specifically, because the superabrasive layer 120 is provided on the outer periphery 112 where the cobalt is scarce, the metal bond enters the pores where the cobalt is scarce, and the superabrasive layer 120 is firmly bonded to the base metal 110. This strong bond is due to the metallic bonding, diffusion bonding, and anchor effect between the metal bond and the cemented carbide alloy in which the pores are provided.

[0020] 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.

[0021] The superabrasive cut-off wheel 100 can rotate in the direction indicated by an 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.

[0022] Preferably, the radial width r of the outer peripheral portion 112 is 0.1 μm or more and 10.0 μm or less. This range of values ​​maximizes the bonding strength of the superabrasive layer 120. The width r is measured as follows: The superabrasive cut-off wheel 100 is cut in the radial direction, and the cross section is smoothed by ion milling (CP treatment: cross-section polisher). This smoothed cross section is photographed using an FE-SEM, and the width r is determined from the resulting image.

[0023] 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).

[0024] Preferably, the content of cobalt in the cemented carbide is 5.0 mass % or more and 35.0 mass % or less.

[0025] 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.

[0026] As the superabrasive grains, diamond grains, cBN (cubic boron nitride) grains, or a mixture thereof can be used.

[0027] 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.

[0028] Superabrasive layer 120 may contain a filler such as alumina, silicon carbide, hBN (hexagonal boron nitride), graphite, or diamond.

[0029] 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.

[0030] (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.

[0031] A masking jig is attached to the base metal 110. This is to limit the target range for Co removal, which will be described later, to only the outer periphery of the base metal 110.

[0032] Next, the solution is added to a strong alkali (sodium hydroxide: 50-100 g / dm3) at a liquid temperature of 60-80°C and a pH of 14 or higher. ３ The metal base 110 is immersed in the solution for 10 to 20 minutes. This removes oil from the surface of the metal base 110.

[0033] Thereafter, the base metal 110 is washed with pure water and ultrasonic waves for 2 to 5 minutes (degreasing treatment), 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).

[0034] The base metal 110 continues to be immersed in concentrated hydrochloric acid at room temperature. The immersion time is appropriately selected depending on the cobalt content of the base metal 110 and the amount of cobalt to be removed. In this process, the cobalt on the surface (radial surface) of the base metal 110 is removed. This forms the outer circumferential portion 112.

[0035] After the cobalt has been removed, nickel plating is formed to a thickness of 5 μm or less on the surface (radial surface) of the base metal 110 .

[0036] Next, the solution is added to a strong alkali (sodium hydroxide: 50-100 g / dm3) at a liquid temperature of 60-80°C and a pH of 14 or higher. ３ The nickel-plated base metal 110 is immersed in the solution for about 10 to 20 minutes.

[0037] The nickel plating is washed with pure water and ultrasonic waves for 2 to 5 minutes. The base metal 110 is immersed in concentrated hydrochloric acid at room temperature adjusted to a pH of 2 to 3 for 3 minutes. This removes rust and surface oxide film from the base metal 110 (acid treatment).

[0038] 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.

[0039] Example: The influence of the difference in cobalt content between the main body portion 111 and the outer periphery portion 112 on the bond strength between the base metal 100 and the superabrasive layer 120 of the superabrasive cut-off wheel 100 was investigated. Figure 2 is a front view of the superabrasive cut-off wheel 100 used to measure the bond strength between the base metal 110 and the superabrasive layer 120. Figure 3 is a cross-sectional view of the superabrasive cut-off wheel taken along the line III-III in Figure 2. As shown in Figures 2 and 3, a cemented carbide base metal 110 was prepared. The cemented carbide alloy was composed of WC and Co. The cobalt content was 5.0% by mass or more and 35.0% by mass or less. Samples 1 to 6 were prepared, each with a diameter D of 100 mm, a radial dimension r of the outer periphery portion 112 of 5 μm, a radial dimension w of the superabrasive layer 120 of 5 mm, and a radial dimension R of the main body portion 111 of 50 mm. A nickel plating layer having a thickness of 3 μm and a copper cyanide plating layer having a thickness of 3 μm (intermediate layer) were provided between base metal 110 and superabrasive grain layer 120. The compositions of sample numbers 1 to 6 are shown in Table 1.

[0040]

[0041] The amount of cobalt in outer peripheral portion 112 was adjusted by adjusting the time for which outer peripheral portion 112 was immersed in concentrated hydrochloric acid at room temperature. The amount of cobalt in main body portion 111 and outer peripheral portion 112 was measured using FE-SEM. In FIG. 2, the arc length of the contact portion between superabrasive layer 120 and base metal 110 is 18 mm, and the thickness t of base metal 110 is 1.4 mm, so the contact area between outer peripheral portion 112 of base metal 110 and superabrasive layer 120 is 25.2 mm. ２ It was.

[0042] As shown in Figure 3, while the base metal 110 side of the joint between the base metal 110 and the superabrasive grain layer 120 was fixed, a force was applied to the superabrasive grain layer 120 in the direction indicated by arrow 200. The force at which the superabrasive grain cut-off wheel 100 broke was divided by the bonded area to determine the bond strength, and the broken portion was also observed. The results are shown in Table 1.

[0043] "Interface failure" indicates that the interface between superabrasive layer 120 and the intermediate layer was broken. "Superabrasive layer failure + interface failure" indicates that superabrasive layer 120 was broken and the interface between superabrasive layer 120 and the intermediate layer was broken.

[0044] From this result, it was confirmed that when the concentration of cobalt in the outer circumferential portion 112 is lower than that in the main body portion 111, the bonding strength of the superabrasive cut-off wheel 100 is increased.

[0045] 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 of the claims.

[0046] 100 Superabrasive cutting wheel, 101 Arrow, 110 Base metal, 111 Main body, 112 Outer periphery, 120 Superabrasive layer, 130 Hole

Claims

1. A superabrasive cut-off wheel comprising: a disk-shaped base metal made of cemented carbide having a main body and an outer periphery provided on the outer periphery of the main body; and a superabrasive layer provided on the outer periphery of the base metal, the superabrasive layer containing superabrasive grains and a metal bond, and the outer periphery having a lower cobalt concentration than the main body.

2. The superabrasive cut-off wheel according to claim 1, wherein the radial width of the outer periphery is 0.1 μm or more and 10.0 μm or less.

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 cobalt content in the cemented carbide is 5.0 mass % or more and 35.0 mass % or less.

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

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