Induction heating coil and heat treatment method

Abstract

To provide an induction heating coil and a heat treatment method that prevent excessive heating of an area that originally requires hardness, such that annealing due to heating does not occur in that area.SOLUTION: An induction heating coil body 3 heat-treats a workpiece 20 that has a heated area A and a heat-avoided area B adjacent to the heated area A, and includes a coil body 5 and a cooling water sprayer 6. The coil body 5 is located close to the heated area A and can raise the temperature of the heated area A. This induction heating coil body 3 can raise the temperature of the heated area A by passing electricity through the coil body 5, while spraying cooling water from below the workpiece 20 toward the heat-avoided area B using the cooling water sprayer 6.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an induction heating coil body and a heat treatment method for heat-treating a workpiece that has a heated area and a heat-avoiding area adjacent to the heated area, wherein the induction heating coil body has a coil body and a cooling water injection means, and relates to an induction heating coil body and a heat treatment method for heat-treating a workpiece. [Background technology]

[0002] In some cases, an annealing process is performed after induction hardening a workpiece. However, in the past, heat was transferred to the annealed area and adjacent areas, resulting in the adjacent areas being annealed. In other words, the hardness of the adjacent areas could decrease, even though they were areas that should have maintained their hardness. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-131638 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention provides an induction heating coil body and a heat treatment method that can prevent areas that originally require hardness from being excessively heated so that annealing due to heating does not occur in those areas. [Means for solving the problem]

[0005] An embodiment for solving the above-mentioned problems is an induction heating coil body for heat-treating a workpiece having a heated portion and a heat-avoided portion adjacent to the heated portion, the induction heating coil body having a coil body and a cooling water injection means, the coil body being close to the heated portion and capable of raising the temperature of the heated portion, the cooling water injection means being capable of injecting cooling water from below the workpiece toward the heat-avoided portion, and the cooling water injection means being capable of injecting cooling water from below the workpiece toward the heat-avoided portion while current is passed through the coil body to raise the temperature of the heated portion.

[0006] According to this aspect, the coil body is located close to the heated portion and can raise the temperature of the heated portion, and the cooling water injection means can inject cooling water from below the workpiece toward the heat-avoided portion. While the heated portion is heated and hardened, the heat-avoided portion is not heated by the injection of cooling water, so the heat-avoided portion is not annealed and can maintain its hardness.

[0007] In the above-described aspect, the induction heating coil body preferably has a concave heating portion.

[0008] According to this aspect, since the heated portion is concave, the heated portion is softened by annealing, and the concave portion can be processed into a groove or the like.

[0009] In each of the above-described aspects, the coil body preferably has a functional area adjacent to the lower surface of the heating portion, and is an induction heating coil body that mainly induction heats the workpiece from below.

[0010] According to this embodiment, the coil body has a functional area adjacent to the underside of the heating area, and the workpiece is mainly induction heated from below. Therefore, the coil body is adjacent to the underside of the heating area and can be installed in a position where cooling water does not splash on the coil body, and further, the workpiece can be easily installed in the functional area of ​​the coil body.

[0011] In each of the above-described aspects, it is preferable that the coil body be annular, have a functional area adjacent to the underside of the heating portion, and a power supply area connecting the power supply unit and the functional area, and that the inscribed circle of the power supply area be larger than the inscribed circle of the functional area.

[0012] According to this aspect, since the inscribed circle of the power supply area is larger than the inscribed circle of the functional area, the workpiece can be first placed in the power supply area and then placed close to the functional area, making it easier to place the workpiece on the coil body.

[0013] In each of the above aspects, the cooling water spraying means is preferably an induction heating coil body that sprays cooling water obliquely toward the heat-rejecting portion.

[0014] According to this aspect, the cooling water injection means injects cooling water obliquely toward the heat-avoiding portion, so that the cooling water can be injected toward the heat-avoiding portion while avoiding the heated portion, and the heated portion is not cooled.

[0015] In each of the above-mentioned aspects, an induction heating coil body in which the coil body and the cooling water injection means are integrated is preferred.

[0016] According to this aspect, the induction heating coil body has the coil body and the cooling water injection means integrated together, so that the temperature of the heated portion and the cooling of the heat-avoided portion can be increased simultaneously, thereby improving work efficiency.

[0017] Another aspect for solving the same problem is a heat treatment method in which a quenched workpiece is rotated while a portion of the workpiece is reheated to anneal the portion, in which the region to be annealed is induction heated while cooling water is sprayed from below onto a region adjacent to the region to be annealed.

[0018] According to this embodiment, while the area to be annealed is induction heated, cooling water is sprayed from below onto the area adjacent to the area to be annealed, so that the cooling water does not accumulate in the area to be annealed and does not hinder the temperature rise of the area to be annealed.

[0019] Another aspect for solving a similar problem is a heat treatment method in which a quenched workpiece is rotated while a portion of the workpiece is reheated to anneal the portion, in which the induction heating coil body of the present invention is used to induction heat the region to be annealed while injecting cooling water from below into a region adjacent to the region to be annealed.

[0020] According to this embodiment, the heated portion of the workpiece is annealed, and cooling water is sprayed from below onto the heat-avoiding portion adjacent to the heated portion, so that the cooling water does not accumulate at the heated portion and therefore does not hinder the temperature rise of the heated portion. [Effects of the Invention]

[0021] According to the induction heating coil and heat treatment method of this aspect, an induction heating coil is used to heat treat a workpiece having a heated portion and a heat-avoided portion adjacent to the heated portion, and the induction heating coil has a coil body and a cooling water injection means, and while current is passed through the coil body to raise the temperature of the heated portion, the cooling water injection means can inject cooling water from below the workpiece toward the heat-avoided portion. Therefore, for example, while heating the heated portion to anneal it, the heat-avoided portion is not excessively heated by the injection of cooling water, and therefore the heat-avoided portion is not annealed, and its hardness can be maintained. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a configuration diagram of a hardening device including an induction heating coil body according to an embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view of the induction heating coil body of the present embodiment. [Figure 3] (a) is a perspective view of the workpiece, and (b) is a front view of the workpiece. [Figure 4] FIG. 2 is a schematic diagram showing a state in which a workpiece is placed in an induction heating coil body. [Figure 5] 1A and 1B are process diagrams showing the heating process, in which (a) is a schematic diagram before the induction heating coil body is placed in the workpiece, (b) is a schematic diagram of the induction heating coil body moved axially so that the power supply area of ​​the induction heating coil body is placed in the workpiece, and (c) is a schematic diagram of the induction heating coil body moved in the vertical direction so that the workpiece is placed in the functional area of ​​the induction heating coil body and the heat treatment process begins. [Figure 6] 1A and 1B are cross-sectional views of a workpiece during annealing, where (a) is a cross-sectional view during annealing, and (b) is an enlarged view of part C in (a). [Figure 7] 1A and 1B are cross-sectional views of a workpiece during annealing, where (a) is a cross-sectional view of the workpiece before annealing, and (b) is a cross-sectional view of the workpiece after annealing. DETAILED DESCRIPTION OF THE INVENTION

[0023] An embodiment of the present invention will be described below. 1 is a configuration diagram of a hardening device including an induction heating coil body of this embodiment. The hardening device 1 of this embodiment has a known high-frequency power supply 10 which is a power supply unit, an induction heating coil body 3, and a mechanism for rotating a workpiece (not shown). The hardening device 1 of this embodiment also has a mechanism for moving the induction heating coil body 3 in the front-to-back and up-and-down directions relative to the workpiece. The high frequency power supply 10 includes a high frequency oscillator 12, a transformer 13, etc., and applies a high frequency current to the induction heating coil body 3.

[0024] The high-frequency oscillator 12 converts the AC power supplied from the commercial power source 11 into high-frequency power and outputs it to the primary side of the transformer 13 .

[0025] The transformer 13 converts the high frequency power supplied to the primary side and outputs it to the secondary side.

[0026] As shown in FIG. 2, the induction heating coil body 3 is a housing 26 in which the coil main body 5 and the cooling water spray device 6 are integrated.

[0027] The coil body 5 has a shape known as a potbellied coil, with a large diameter region 8 and a small diameter region 14 connected together. The large diameter region 8 is a large-diameter arc-shaped portion with an angle of approximately 180 degrees or more, and is the power supply region. The small diameter region 14 is a circular arc of approximately 180 degrees, smaller than the large diameter region 8, and is the functional region. The small diameter region 14 on the lower side of the coil body 5 contributes to heating, so this portion is called the functional region. The power supply region is the region connecting the power supply part and the functional region.

[0028] As is well known, the coil body 5, which is made up of the large diameter region 8 and the small diameter region 14, has internal communication holes through which cooling water passes. The device for cooling the coil body 5 and the cooling water path of the coil body 5 are not shown.

[0029] The cooling water sprayer 6 is provided adjacent to the coil body 5. As shown in Figure 6, the cooling water sprayer 6 is located near the coil body 5 and is provided with a spray nozzle 16 that sprays cooling water from below at a spray angle θ directed obliquely away from the coil body 5. Cooling water is supplied to the cooling water sprayer 6 from a cooling water supply pipe 27. The cooling water sprayer 6 is formed in an arc shape along the functional area.

[0030] 3 is cylindrical, has concave grooves 22 on both ends, and has already been hardened throughout its entirety. Only the grooves 22 of the hardened workpiece 20 are annealed, and the other parts are not annealed. That is, the groove 22 of the workpiece 20 corresponds to the heating area A, and the other area corresponds to the heat-avoiding area B. For ease of understanding, Figure 5 shows only the coil body 5 without the cooling water spray device 6, and illustrates the movement of only the coil body 5. However, in an actual induction heating coil body 3, the coil body 5 and the cooling water spray device 6 are integrated, so the cooling water spray device 6 also moves along with the coil body 5.

[0031] In this embodiment, annealing is performed with the small diameter region 14 of the coil body 5 brought close to the workpiece 20, so that the coil body 5 can be made to conform to the shape of the cylindrical workpiece 20 and can be efficiently annealed. The adjacent heat-avoiding area B is cooled by the cooling water sprayed from the cooling water spraying device 6, so it does not rise in temperature excessively and is not annealed. The heated area A is not cooled, and because the cooling water is sprayed from below, it hits only the heat-avoiding area B and falls. Therefore, the cooling water does not hit the heated area A or accumulate in the groove 22, so the heated area A can be annealed efficiently.

[0032] Furthermore, in this embodiment, the cooling water is sprayed from below the workpiece 20 at an angle away from the coil body 5, so that the cooling water does not splash on the coil body 5, allowing for efficient annealing.

[0033] A heat treatment method according to an embodiment of the present invention will be described below. Fig. 4 is a schematic diagram of the workpiece 20 placed in the coil body 5. Fig. 5 is a process diagram showing the heating process, in which the induction heating coil body 3 is moved axially as shown in Fig. 5(a) and (b) to place the workpiece 20 in the large diameter region 8 of the coil body 5. Then, as shown in Fig. 5(c), the induction heating coil body 3 is moved upward to place the workpiece 20 in the small diameter region 14 of the coil body 5. In this state, current is applied to the coil body 5 to heat the workpiece 20.

[0034] A cross-sectional view of the workpiece during annealing is shown in Fig. 7. Fig. 7(a) is a cross-sectional view of the workpiece 20 before annealing, and Fig. 7(b) is a cross-sectional view of the workpiece 20 after annealing. In Figure 7(a), the hardened layer 28 has already been formed. When the heated portion A is subsequently annealed, the hardened layer 28 at the heated portion A of the workpiece 20 softens, as shown in Figure 7(b), and a layer 24 is formed on the surface of the hardened layer 28. Because the layer 24 has been softened, it can be easily machined.

[0035] In this embodiment, the power supply area is arc-shaped, but it is not limited to an arc-shaped area and may be polygonal, such as a square.

[0036] Although the present embodiment has been described as a case where annealing is performed, the present invention can also be used for quenching. That is, the part to be quenched is heated, and cooling water is sprayed onto the adjacent part that is not to be quenched to prevent the heat from being transferred from the part to be quenched. At this time, the cooling water is sprayed from below the workpiece to prevent the cooling water from pooling on the workpiece.

[0037] According to this embodiment, while the coil body is energized to raise the temperature of the heated portion, the cooling water spray device can spray cooling water from below the workpiece toward the heat-avoided portion. Therefore, while the heated portion is hardened, the heat-avoided portion is not heated by the spraying of cooling water, so it is not annealed and its hardness can be maintained. [Explanation of symbols]

[0038] 1. Hardening equipment 3. Induction heating coil body 5 Coil body 6 Cooling water injection device 8 Large diameter area (power supply area) 14 Small diameter area (functional area) 16 spray nozzle 20 Work 22 Groove 24 layers

Claims

1. An induction heating coil body for heat-treating a workpiece having a heating portion and a heat-avoiding portion adjacent to the heating portion, The coil body has a coil body and a cooling water injection means, and the coil body is in proximity to the heating portion and can raise the temperature of the heating portion, The cooling water injection means is capable of injecting cooling water from below the workpiece toward the heat avoidance portion, An induction heating coil body characterized in that while current is passed through the coil body to raise the temperature of the heated portion, cooling water can be sprayed from below the workpiece toward the heat-avoiding portion using the cooling water spraying means.

2. 2. The induction heating coil assembly according to claim 1, wherein the heating portion is concave.

3. 3. The induction heating coil body according to claim 1, wherein the coil body has a functional area adjacent to a lower surface of the heating portion, and mainly inductively heats the workpiece from below.

4. 4. The induction heating coil body according to claim 3, wherein the coil body is annular and has a functional area adjacent to a lower surface of the heating portion and a power supply area connecting a power supply unit and the functional area, and the inscribed circle of the power supply area is larger than the inscribed circle of the functional area.

5. 5. The induction heating coil assembly according to claim 4, wherein the cooling water jetting means jets cooling water obliquely toward the heat-rejecting portion.

6. 6. The induction heating coil body according to claim 5, wherein the coil body and the cooling water injection means are integrated.

7. A heat treatment method in which a quenched workpiece is rotated while a portion of the workpiece is reheated to anneal the portion, A heat treatment method characterized by injecting cooling water from below into an area adjacent to the area where annealing is to be performed while induction heating the area where annealing is to be performed.

8. A heat treatment method in which a quenched workpiece is rotated while a portion of the workpiece is reheated to anneal the portion, 10. A heat treatment method comprising: using the induction heating coil body according to claim 1 to induction heat the region where the annealing is to be performed; and injecting cooling water from below into a region adjacent to the region where the annealing is to be performed.

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