Heating coil and high-frequency induction hardening device

Abstract

The present invention provides a heating coil and high-frequency induction hardening apparatus that enable both uniform heating of the workpiece and rapid cooling of the heated workpiece. [Solution] The heating coil comprises a first arc portion having a radius of a first inner radius, a second arc portion having a second inner radius larger than the first inner radius, a third arc portion having a third inner radius smaller than the second inner radius, a fourth arc portion overlapping with the second arc portion when viewed from a first direction from which the central axis of the first arc portion extends, and having an inner radius of the second inner radius, a fifth arc portion having an inner radius of the third inner radius, and a sixth arc portion overlapping with the second arc portion when viewed from the first direction, having an inner radius of the second inner radius, and electrically connected to the fifth arc portion.

Description

Technical Field

[0001] Embodiments of the present invention relate to a heating coil and a high-frequency quenching device.

Background Art

[0002] When performing quenching treatment on a workpiece using a high-frequency quenching device, it may be desirable to uniformly heat the entire workpiece. To uniformly heat the entire workpiece, it is preferable to arrange the heating coil at a position where the distance from the surface of the workpiece is as constant as possible. On the other hand, in order to quickly cool the heated workpiece, it is preferable that the workpiece be movable between the heating coil and the cooling means. However, if the workpiece has portions with different diameters, the heating coil arranged near the portion with a smaller diameter may interfere with the portion with a larger diameter, preventing the movement of the workpiece.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of embodiments of the present invention is to provide a heating coil and a high-frequency quenching device that enable both uniform heating of a workpiece and rapid cooling of the heated workpiece.

Means for Solving the Problems

[0005] A heating coil according to an embodiment of the present invention comprises: a first arc portion having an inner radius of a first inner radius; a second arc portion having an inner radius of a second inner radius larger than the first inner radius; a third arc portion having an inner radius different from the first inner radius and smaller than the second inner radius, with its central axis coinciding with the central axis of the first arc portion; a fourth arc portion that overlaps with the second arc portion when viewed from a first direction from which the central axis of the first arc portion extends, has an inner radius of the second inner radius, has a central axis coinciding with the central axis of the second arc portion, and is electrically connected to the third arc portion; a fifth arc portion having an inner radius of the third inner radius, with a central axis coinciding with the central axes of the first and third arc portions; and a sixth arc portion that overlaps with the second and fourth arc portions when viewed from a first direction, has an inner radius of the second inner radius, has a central axis coinciding with the central axes of the second and fourth arc portions, and is electrically connected to the fifth arc portion. The heating coil includes a first portion whose outer radius is smaller than the first inner radius, a second portion whose outer radius is larger than the first inner radius and smaller than the second inner radius, and a third portion whose outer radius is equal to the outer radius of the second portion, and heats a workpiece in which the second portion, the first portion and the third portion are arranged in this order along the central axis.

[0006] An embodiment of the present invention provides a high-frequency induction hardening apparatus comprising: a heating coil; a cooling means positioned at a distance from the heating coil in the first direction for cooling the workpiece heated by the heating coil; and a moving means capable of changing the positional relationship between the workpiece, the heating coil, and the cooling means between a first relationship in which a part of the workpiece is located within the first arc portion when viewed from the first direction and a second relationship in which a second part of the workpiece is separated from the first arc portion of the heating coil when viewed from the first direction, as well as a third relationship in which the workpiece can be cooled by the cooling means. [Effects of the Invention]

[0007] According to embodiments of the present invention, a heating coil and a high-frequency induction hardening apparatus can be realized that enable both uniform heating of the workpiece and rapid cooling of the heated workpiece. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a block diagram showing a high-frequency induction hardening apparatus according to the first embodiment. [Figure 2] Figure 2 is a perspective view showing the workpiece in the first embodiment. [Figure 3] Figure 3 is a perspective view showing the heating coil and workpiece according to the first embodiment. [Figure 4] Figure 4 is a perspective view showing a heating coil according to the first embodiment. [Figure 5] Figure 5 is a perspective view showing the outer periphery of the heating coil according to the first embodiment. [Figure 6] Figure 6 is a perspective view showing the outer periphery of the heating coil according to the first embodiment. [Figure 7] Figure 7 is a perspective view showing the outer periphery of the heating coil according to the first embodiment. [Figure 8] Figure 8 is a top view showing the outer periphery of the heating coil and the workpiece according to the first embodiment. [Figure 9] Figure 9 is a cross-sectional view showing the outer periphery of the heating coil and the workpiece according to the first embodiment. [Figure 10] Figures 10(a) to 10(c) show the operation of the high-frequency induction hardening apparatus according to the first embodiment. [Figure 11] Figure 11 is a cross-sectional view showing a heating coil and workpiece according to a second embodiment. [Figure 12] Figure 12 is a top view showing a heating coil and workpiece according to a third embodiment. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a block diagram showing a high-frequency induction hardening apparatus according to this embodiment. As shown in FIG. 1, in the high-frequency quenching device 1 according to the present embodiment, a heating coil 10, a cooling means 80, and a moving means 90 are provided. The high-frequency quenching device 1 performs a quenching process on a workpiece 100. The workpiece 100 is a steel member. The heating coil 10 heats the workpiece 100 by high frequency. The cooling means 80 cools the workpiece 100 heated by the heating coil 10. The moving means 90 can change the positional relationship among the workpiece 100, the heating coil 10, and the cooling means 80.

[0010] First, the workpiece 100 that is the object of the high-frequency quenching process in the present embodiment will be described. FIG. 2 is a perspective view showing the workpiece in the present embodiment. As shown in FIG. 2, the shape of the workpiece 100 is a rotating body. Along the central axis 100C of the workpiece 100, a portion 101, a portion 102 (second portion), a portion 103 (first portion), and a portion 104 are provided in this order. The portions 101 to 104 are integrally formed of steel. The outer radius R2 of the portion 102 (second portion) is larger than the outer radius R1 of the portion 103 (first portion). Also, the outer radius R3 of the portion 101 is smaller than the outer radius R1. The outer radius of the portion 104 is equal to the outer radius R2. That is, R3 < R1 < R2.

[0011] Further, a through hole 110 is provided in the workpiece 100 along the central axis 100C. The central axis of the through hole 110 coincides with the central axis 100C. The workpiece 100 is, for example, a track roller of a caterpillar.

[0012] Next, the heating coil 10 will be described. FIG. 3 is a perspective view showing the heating coil and the workpiece according to the present embodiment. FIG. 4 is a perspective view showing the heating coil according to the present embodiment. FIG. 5 is a perspective view showing the outer peripheral portion of the heating coil according to the present embodiment. FIG. 6 is a perspective view showing the outer peripheral portion of the heating coil according to the present embodiment. FIG. 7 is a perspective view showing the outer peripheral portion of the heating coil according to the present embodiment. FIG. 8 is a top view showing the outer periphery of the heating coil and the workpiece according to the present embodiment. FIG. 9 is a cross-sectional view showing the outer periphery of the heating coil and the workpiece according to the present embodiment. FIG. 4 is a view in which the workpiece 100 is omitted from FIG. 3. FIGS. 5 to 7 are views in which the inner peripheral portion 71 of the heating coil 10 is omitted from FIG. 4, and are views seen from different directions. Also in FIGS. 8 and 9, the inner peripheral portion 71 of the heating coil 10 is omitted.

[0013] As shown in FIG. 3, in the heating coil 10, an outer peripheral portion 11 disposed outside the workpiece 100 and an inner peripheral portion 71 disposed inside the through-hole 110 of the workpiece 100 are provided when heating the workpiece 100. The outer peripheral portion 11 and the inner peripheral portion 71 are spaced apart from each other.

[0014] As shown in FIGS. 3 to 9, the outer peripheral portion 11 is formed by bending a single metal pipe, for example, a single square pipe 12 made of copper. The square pipe 12 is a single current path, and a flow path through which a coolant flows is formed inside. The coolant is, for example, water.

[0015] One end portion of the square pipe 12 is a vertical portion 21 extending in the vertical direction. An electrode 13 is joined to the vertical portion 21. A coolant supply / discharge port 15 is attached to the upper end of the vertical portion 21. The other end portion of the square pipe 12 is a vertical portion 67 extending in the vertical direction. An electrode 14 is joined to the vertical portion 67. A coolant supply / discharge port 15 is attached to the upper end of the vertical portion 67. Also, the supply / discharge ports 15 are attached in pairs to the arc portion 34, the arc portion 42, and the arc portion 54. That is, a total of eight supply / discharge ports 15 are attached to the square pipe 12.

[0016] The square pipe 12 has, from one end to the other, a vertical section 21, a horizontal section 22, a straight section 23, an arc section 24, a straight section 25, a semicircular section 26, a straight section 27, an arc section 28, a vertical section 29, an arc section 30, a straight section 31, a semicircular section 32, a straight section 33, an arc section 34, a vertical section 35, an arc section 36, a straight section 37, a semicircular section 38, a straight section 39, an arc section 40, a vertical section 41, an arc section 42, and a straight section. It forms part 43, semicircular part 44, straight part 45, arc part 46, vertical part 47, arc part 48, straight part 49, semicircular part 50, straight part 51, arc part 52, vertical part 53, arc part 54, straight part 55, semicircular part 56, straight part 57, arc part 58, vertical part 59, arc part 60, straight part 61, semicircular part 62, straight part 63, arc part 64, straight part 65, horizontal part 66, and vertical part 67.

[0017] The shape of each semicircular section described above is semicircular; that is, the central angle of each semicircular section is approximately 180 degrees. The shape of each arc section is arc-shaped; the central angle of each arc section is less than 180 degrees. The shape of each vertical section is a straight line extending in the vertical direction. The shape of each straight section is a straight line extending in the horizontal direction. The central axes of each semicircular section and each arc section coincide with each other. This central axis is defined as the central axis C of the heating coil 10. The central axis C extends, for example, in the vertical direction.

[0018] Of the square pipe 12, the superstructure 17 consisting of two turns is formed by the arc section 24, the straight section 25, the semicircular section 26, the straight section 27, the arc section 28, the vertical section 29, the arc section 30, the straight section 31, the semicircular section 32, the straight section 33, and the arc section 34.

[0019] Arc section 24, semicircular section 26, and arc section 28 are arranged on the same plane. Arc section 30, semicircular section 32, and arc section 34 are arranged on the same plane. Arc section 30 is located directly below arc section 24. Arc section 34 is located directly below arc section 28. Semicircular section 32 is located directly below semicircular section 26. Arc section 28 is connected to arc section 30 by a vertical section 29, and descends one step. The sum of the central angles of arc section 28 and arc section 30 is approximately 180 degrees. Of the superstructure 17, semicircular sections 26 and 32 correspond to the fifth arc section 17a, respectively. The semicircle formed by arc section 28 and arc section 30 corresponds to the sixth arc section 17b.

[0020] Of the square pipe 12, the central structure 18, consisting of three turns, is formed by the arc section 36, the straight section 37, the semicircular section 38, the straight section 39, the arc section 40, the vertical section 41, the arc section 42, the straight section 43, the semicircular section 44, the straight section 45, the arc section 46, the vertical section 47, the arc section 48, the straight section 49, the semicircular section 50, the straight section 51, and the arc section 52.

[0021] Arc section 36, semicircular section 38, and arc section 40 are located on the same plane. Arc section 42, semicircular section 44, and arc section 46 are located on the same plane. Arc section 48, semicircular section 50, and arc section 52 are located on the same plane. Arc section 42 is located directly below arc section 36. Arc section 46 is located directly below arc section 40. Arc section 48 is located directly below arc section 42. Arc section 52 is located directly below arc section 46. Semicircular section 44 is located directly below semicircular section 38. Semicircular section 50 is located directly below semicircular section 44. Arc section 40 is connected to arc section 42 by a vertical section 41, and descends one step. The sum of the central angles of arc section 40 and arc section 42 is approximately 180 degrees. The arc section 46 is connected to the arc section 48 by the vertical section 47, and descends by one step. The sum of the central angles of the arc section 46 and the arc section 48 is approximately 180 degrees.

[0022] Of the central structure 18, the semicircular sections 38, 44, and 50 each correspond to the first arc section 18a. The semicircles formed by arc sections 40 and 42, and the semicircles formed by arc sections 46 and 48, each correspond to the second arc section 18b. The upper structure 17 and the central structure 18 are connected by a vertical section 35.

[0023] Of the square pipe 12, the lower structure 19, consisting of two turns, is formed by the arc section 54, the straight section 55, the semicircular section 56, the straight section 57, the arc section 58, the vertical section 59, the arc section 60, the straight section 61, the semicircular section 62, the straight section 63, and the arc section 64.

[0024] Arc section 54, semicircular section 56, and arc section 58 are arranged on the same plane. Arc section 60, semicircular section 62, and arc section 64 are arranged on the same plane. Arc section 60 is located directly below arc section 54. Arc section 64 is located directly below arc section 58. Semicircular section 62 is located directly below semicircular section 56. Arc section 58 is connected to arc section 60 by a vertical section 59, and descends by one step. The sum of the central angles of arc section 58 and arc section 60 is approximately 180 degrees.

[0025] Of the lower structure 19, the semicircular sections 56 and 62 correspond to the third arc section 19a, respectively. The semicircle formed by the arc sections 58 and 60 corresponds to the fourth arc section 19b. The middle structure 18 and the lower structure 19 are connected by a vertical section 53.

[0026] The inner radii of the semicircular sections 38, 44, and 50, which constitute the first arc portion 18a, are all the first inner radius r1. The inner radii of the semicircles formed by arc sections 40 and 42, which constitute the second arc portion 18b, and the semicircles formed by arc sections 46 and 48, are all the second inner radius r2. The second inner radius r2 is larger than the first inner radius r1. The inner radii of the semicircular sections 56 and 62, which constitute the third arc portion 19a, are all the third inner radius r3. The third inner radius r3 is smaller than the first inner radius r1. That is, r3 <r1<r2である。

[0027] The inner radius of the semicircle formed by arc sections 58 and 60, which constitute the fourth arc section 19b, is the second inner radius r2. The inner radius of the semicircle formed by semicircle sections 26 and 32, which constitute the fifth arc section 17a, is the third inner radius r3. The inner radius of the semicircle formed by arc sections 28 and 30, which constitute the sixth arc section 17b, is the second inner radius r2.

[0028] The dimensional relationship between the heating coil 10 and the workpiece 100 is as follows: As shown in Figure 9, the outer radius R3 of part 101 of workpiece 100 is smaller than the third inner radius r3 of the heating coil 10. The outer radii R2 of parts 102 (second part) and 104 of workpiece 100 are greater than the first inner radius r1 of the heating coil 10 and smaller than the second inner radius r2. The outer radius R1 of part 103 (first part) of workpiece 100 is greater than the third inner radius r3 of the heating coil 10 and smaller than the first inner radius r1. That is, R3 <r3<R1<r1<R2<r2である。

[0029] Next, the inner circumference 71 of the heating coil 10 will be described. As shown in Figure 4, the inner circumference 71 is formed by bending a single metal pipe, for example, a single square pipe 72 made of copper. The square pipe 72 serves as a current path and also has a flow path through which a coolant flows. The coolant is, for example, water. An electrode 73 is connected to one end of the square pipe 72, and an electrode 74 is connected to the other end. The middle section of the square pipe 72 is, for example, a four-turn spiral. For example, two pairs of coolant inlet and outlet ports 75 are attached to the square pipe 72.

[0030] As shown in Figure 1, the cooling means 80 is positioned at a distance from the heating coil 10 in the direction in which the central axis C of the heating coil 10 extends. For example, the cooling means 80 is positioned directly below the heating coil 10. The cooling means 80 cools the workpiece 100 heated by the heating coil 10 by spraying a cooling liquid onto it. The cooling liquid is, for example, water.

[0031] The moving mechanism 90 includes a horizontal moving section 91 (first moving section) that moves the outer periphery 11 of the heating coil 10 in the horizontal direction, a vertical moving section 92 (second moving section) that moves the workpiece 100 in the vertical direction, and a control unit 93 that controls the horizontal moving section 91 and the vertical moving section 92. The control unit 93 may also control the heating coil 10 and its power supply unit, as well as the cooling mechanism 80 and its coolant supply unit.

[0032] The moving means 90, by coordinating the horizontal moving part 91 and the vertical moving part 92, can arrange the positional relationship of the workpiece 100, the heating coil 10, and the cooling means 80 such that, when viewed from the direction in which the central axis C extends, a part of the workpiece 100 is located inside the semicircular parts 38, 44, and 50 which are the first arc portion 18a, the semicircular parts 56 and 62 which are the third arc portion 19a, and the semicircular parts 26 and 32 which are the fifth arc portion 17a. This relationship is called the "first relationship".

[0033] In the first relationship, the remaining part of the workpiece 100, when viewed from the direction in which the central axis C extends, is located inside the semicircle consisting of the second arc portion 18b, which is the arc portion 40 and the arc portion 42, the semicircle consisting of the arc portion 46 and the arc portion 48, the semicircle consisting of the fourth arc portion 19b, which is the arc portion 58 and the arc portion 60, and the semicircle consisting of the sixth arc portion 17b, which is the arc portion 28 and the arc portion 30.

[0034] Furthermore, by coordinating the horizontal movement section 91 and the vertical movement section 92 of the moving means 90, the positional relationship between the workpiece 100, the heating coil 10, and the cooling means 80 can be such that, when viewed from the direction in which the central axis C extends, the portion 102 (second portion) of the workpiece 100 is separated from the semicircular portions 38, 44, and 50, which are the first arc portion 18a of the heating coil 10. This relationship is called the "second relationship".

[0035] Furthermore, in the second relationship, at least a portion of the workpiece 100 is located inside the semicircle consisting of the arc portion 40 and arc portion 42, which is the second arc portion 18b, the semicircle consisting of the arc portion 46 and arc portion 48, the semicircle consisting of the arc portion 58 and arc portion 60, which is the fourth arc portion 19b, and the semicircle consisting of the arc portion 28 and arc portion 30, which is the sixth arc portion 17b.

[0036] Specifically, the horizontal movement unit 91 moves the outer periphery 11 of the heating coil 10 in the horizontal direction, thereby changing the positional relationship between the workpiece 100, the heating coil 10, and the cooling means 80 between the first and second relationships described above.

[0037] Furthermore, by coordinating the horizontal movement section 91 and the vertical movement section 92 of the moving means 90, the positional relationship between the workpiece 100, the heating coil 10, and the cooling means 80 can be adjusted so that the workpiece 100 can be cooled by the cooling means 80. This relationship is referred to as the "third relationship."

[0038] Specifically, the vertical movement unit 92 moves the workpiece 100 in the vertical direction, thereby changing the positional relationship between the workpiece 100, the heating coil 10, and the cooling means 80 between the second and third relationships described above.

[0039] Next, the operation of the high-frequency induction hardening apparatus 1 according to this embodiment will be described. Figures 10(a) to 10(c) show the operation of the high-frequency induction hardening apparatus according to this embodiment. Note that in Figures 10(a) to (c), the inner circumference 71 of the heating coil 10 is omitted.

[0040] First, as shown in Figures 1 and 10(a), the moving means 90 sets the positional relationship between the workpiece 100, the heating coil 10, and the cooling means 80 to the first relationship described above. That is, viewed from the direction in which the central axis C extends, a portion of the workpiece 100 is positioned within the first arc portion 18a, the third arc portion 19a, and the fifth arc portion 17a of the outer circumference 11 of the heating coil 10. Also, the inner circumference 71 of the heating coil 10 is positioned within the through hole 110 of the workpiece 100. At this time, the central axis 100C of the workpiece 100 is aligned with the central axis C of the heating coil 10. Then, the workpiece 100 is rotated around the central axis 100C.

[0041] Next, the coolant is circulated through the square pipe 12 on the outer circumference 11 of the heating coil 10 via the supply and discharge port 15. The coolant is also circulated through the square pipe 72 on the inner circumference 71 via the supply and discharge port 75. For example, water is used as the coolant.

[0042] In this state, a high-frequency current is supplied to the square pipe 12 via electrodes 13 and 14, and a high-frequency current is supplied to the square pipe 72 via electrodes 73 and 74. As a result, the workpiece 100 is inductively heated. The workpiece 100 rotates and is heated from the outside by the outer circumference 11 of the heating coil 10 and from the inside by the inner circumference 71. From the perspective of the workpiece 100, each semicircular portion of the heating coil 10 (first arc portion 18a, third arc portion 19a, and fifth arc portion 17a) is located closer than each arc portion (second arc portion 18b, fourth arc portion 19b, and sixth arc portion 17b), so the heating from each semicircular portion is stronger than the heating from each arc portion.

[0043] When the workpiece 100 is heated to a predetermined temperature, for example, a temperature above the austenite transformation point, the supply of high-frequency current to the heating coil 10 is stopped. This stops the heating of the workpiece 100.

[0044] Next, as shown in Figure 10(b), the horizontal moving part 91 of the moving means 90 moves the outer circumference 11 of the heating coil 10 horizontally to achieve the second relationship described above. That is, when viewed from the direction in which the central axis C extends, the portion 102 (second portion) of the workpiece 100 is moved away from the semicircular portions 38, 44, and 50, which are the first circular arc portion 18a of the heating coil 10.

[0045] Next, as shown in Figure 10(c), the vertical movement portion 92 of the moving means 90 lowers the workpiece 100 to achieve the third relationship described above. That is, the workpiece 100 is positioned in a location where it can be cooled by the cooling means 80. For example, the workpiece 100 is positioned in a location surrounded by the cooling means 80.

[0046] Next, the cooling means 80 sprays coolant onto the workpiece 100. This rapidly cools the surface of the workpiece 100, causing it to harden by quenching. In this way, the surface of the workpiece 100 is subjected to a quenching treatment.

[0047] Next, the effects of this embodiment will be described. According to this embodiment, when the workpiece 100 and the heating coil 10 are in a first positional relationship, the semicircular portions (first arc portion 18a, third arc portion 19a, and fifth arc portion 17a) of the outer circumference 11 of the heating coil 10 are arranged along the outer surface of the workpiece 100. Furthermore, the central axis C of each semicircular portion is aligned with the central axis 100C of the workpiece 100. In addition, the workpiece 100 is heated while rotating around the central axis 100C. This allows the workpiece 100 to be heated uniformly. In particular, the heating coil 10 can be brought close to portions 101 and 103 (first portion) of the workpiece 100, which have relatively small outer radii, to ensure that these portions are heated.

[0048] Furthermore, arc sections (second arc section 18b, fourth arc section 19b, and sixth arc section 17b) are provided on the outer circumference 11 of the heating coil 10, and the central axis of each arc section is aligned with the central axis 100C of the workpiece 100. This allows for uniform heating by the arc sections even when each part of the workpiece 100 is located on the opposite side of the semicircular section.

[0049] Furthermore, after heating is complete, the moving means 90 moves the outer circumference 11 of the heating coil 10, changing the positional relationship between the workpiece 100 and the heating coil 10 from a first relationship to a second relationship, thereby separating the workpiece 100 from the semicircular portion of the heating coil 10. As a result, even if the workpiece 100 is moved downward relative to the heating coil 10, the portion 102 (second portion) and portion 104 of the workpiece 100, which have a relatively large outer radius, will no longer come into contact with the portion (semicircular portion) of the heating coil 10, which have a relatively small inner radius. Consequently, it becomes possible to change the positional relationship between the workpiece 100, the heating coil 10, and the cooling means 80 from a second relationship to a third relationship.

[0050] By setting the positional relationship to a third relationship, the workpiece 100, immediately after being heated by the heating coil 10, can be rapidly cooled by the cooling means 80. Thus, according to this embodiment, it is possible to achieve both uniform heating of the workpiece 100 and rapid cooling of the workpiece 100.

[0051] Furthermore, in this embodiment, since the outer circumference 11 and inner circumference 71 of the heating coil 10 are each made of a single metal pipe, high-frequency current loss can be suppressed, and coolant can be circulated within the outer circumference 11 and inner circumference 71. In addition, since the square pipe 12 is provided with multiple pairs of supply and discharge ports 15, heated coolant can be discharged along the flow path, and unheated coolant can be supplied. This improves the cooling efficiency of the square pipe 12. The same applies to the square pipe 72.

[0052] In this embodiment, the heating coil 10 does not necessarily have an inner circumference 71. Also, in the outer circumference 11 of the heating coil 10, the upper structure 17, the middle structure 18, and the lower structure 19 may each consist of only one turn, or they may each consist of four or more turns.

[0053] <Second Embodiment> This embodiment is a simplified version of the first embodiment described above. Figure 11 is a cross-sectional view showing the heating coil and workpiece according to this embodiment.

[0054] As shown in Figure 11, the heating coil 10a according to this embodiment is provided only with an outer circumference 11, and no inner circumference 71. Furthermore, the outer circumference 11 is provided only with a first arc portion 18a and a second arc portion 18b, and no third to sixth arc portions are provided. The central angles of the first arc portion 18a and the second arc portion 18b are both approximately 180 degrees.

[0055] Furthermore, in this embodiment, the workpiece 100a subjected to the hardening treatment is provided only with portion 103 (first portion) and portion 102 (second portion), and does not have portions 101, 104, or the through hole 110.

[0056] The second inner radius r2 of the second arc portion 18b of the heating coil 10a is greater than the first inner radius r1 of the first arc portion 18a. Also, the outer radius R1 of portion 103 (first portion) of the workpiece 100a is smaller than the first inner radius r1 of the heating coil 10a. Furthermore, the outer radius R2 of portion 102 (second portion) is greater than the first inner radius r1 of the workpiece 100a and smaller than the second inner radius r2. That is, R1 <r1<R2<r2である。

[0057] In this embodiment, when the relative position of the workpiece 100a with respect to the heating coil 10a is a first position P1 that satisfies the above-described first relationship, the heating coil 10a heats the workpiece 100a by high-frequency induction. At this time, since the first arc portion 18a of the heating coil 10a is positioned near portion 103 (first portion) of the workpiece 100a, the workpiece 100a can be heated uniformly.

[0058] After heating is complete, if the moving means 90 (see Figure 1) attempts to lower the workpiece 100a directly from the first position P1, portion 102 (second portion) of the workpiece 100a will come into contact with the first arc portion 18a of the heating coil 10a. For this reason, the moving means 90 temporarily sets the relative position of the workpiece 100a with respect to the heating coil 10a to the second position P2, which satisfies the second relationship described above. At this time, the moving means 90 may move the heating coil 10a or move the workpiece 100a. As a result, when viewed from the direction in which the central axis C extends, portion 102 (second portion) of the workpiece 100a moves away from the first arc portion 18a of the heating coil 10a.

[0059] Subsequently, the moving means 90 moves the workpiece 100a to a third position P3 that satisfies the third relationship described above. During the movement from the second position P2 to the third position P3, the workpiece 100a does not come into contact with the heating coil 10a. Then, the cooling means 80 (see Figure 1) cools the workpiece 100a. In this way, the workpiece 100a heated by the heating coil 10a can be quickly cooled by the cooling means 80. The configuration, operation, and effects of this embodiment other than those described above are the same as those of the first embodiment described above.

[0060] <Third Embodiment> This embodiment is an example in which the central angle of each arc portion of the heating coil is an angle other than 180 degrees. Figure 12 is a top view showing the heating coil and workpiece according to this embodiment. In Figure 12, only part 103 (first part) of workpiece 100a is shown, and part 102 (second part) is omitted.

[0061] As shown in Figure 12, the heating coil 10b according to this embodiment is provided with a first arc portion 18c and a second arc portion 18d. The second inner radius r2 of the second arc portion 18d is larger than the first inner radius r1 of the first arc portion 18c. Furthermore, the central angle θ1 of the first arc portion 18c is less than 180 degrees, and the central angle θ2 of the second arc portion 18d is greater than 180 degrees. This also allows for the same effects as in the first and second embodiments to be obtained. The configuration, operation, and effects of this embodiment other than those described above are the same as those of the second embodiment described above.

[0062] The embodiments described above are examples that embody the present invention, and the present invention is not limited to these embodiments. For example, the present invention is also included in the embodiments described above in which some components are added, deleted, or modified. For example, in the outer circumference 11 of the heating coil 10, the upper structure 17, the middle structure 18, and the lower structure 19 may each consist of only one turn or four or more turns. Also, the central angles of the first arc portion 18a, the third arc portion 19a, and the fifth arc portion 17a may be different from each other, and the central angles of the second arc portion 18b, the fourth arc portion 19b, and the sixth arc portion 17b may be different from each other. However, in order to smoothly transition from the first relationship to the second relationship, it is preferable that the central angles of the first arc portion 18a, the third arc portion 19a, and the fifth arc portion 17a are 180 degrees or less. [Explanation of Symbols]

[0063] 1: High-frequency induction hardening equipment 10, 10a, 10b: Heating coil 11: Outer perimeter 12: Square pipe 13, 14: Electrode 15: Supply / discharge port 17:Superstructure 17a: Fifth arc section 17b: Sixth arc section 18: Middle structure 18a, 18c: First arc section 18b, 18d: Second arc section 19: Substructure 19a: Third arc section 19b: Fourth arc section 21, 29, 35, 41, 47, 53, 59, 67: Vertical section 22, 66: Horizontal part 23, 25, 27, 31, 33, 37, 39, 43, 45, 49, 51, 55, 57, 61, 63, 65: Straight section 24, 28, 30, 34, 36, 40, 42, 46, 48, 52, 54, 58, 60, 64: Arc section 26, 32, 38, 44, 50, 56, 62: Semicircular section 71: Inner circumference 72: Square pipe 73, 74: Electrode 75: Supply / discharge port 80: Cooling means 90: Means of transportation 91: Horizontal movement part 92: Vertical moving part 93: Control Unit 100, 100a: Work 100C: Workpiece central axis 101, 102, 103, 104: Part 110: Through hole C: Central axis P1: 1st position P2: 2nd position P3: 3rd position R1: 1st outer radius R2: 2nd outer radius R3: Third outer radius r1: First inner radius r2: 2nd inner radius r3: 3rd inner radius

Claims

1. The first circular arc portion has an inner radius of the first inner radius, A second circular arc portion having a second inner radius that is larger than the first inner radius, A third circular arc portion having an inner radius different from the first inner radius and smaller than the second inner radius, and whose central axis coincides with the central axis of the first circular arc portion, A fourth arc portion is electrically connected to the third arc portion, having an inner radius equal to the second inner radius, and its central axis coincides with the central axis of the second arc portion when viewed from a first direction in which the central axis of the first arc portion extends. A fifth arc portion whose inner radius is the third inner radius and whose central axis coincides with the central axes of the first and third arc portions, A sixth arc portion, viewed from the first direction, overlaps with the second and fourth arc portions, has an inner radius equal to the second inner radius, and its central axis coincides with the central axes of the second and fourth arc portions, and is electrically connected to the fifth arc portion. Equipped with, A workpiece is heated, comprising a first portion whose outer radius is smaller than the first inner radius, a second portion whose outer radius is larger than the first inner radius and smaller than the second inner radius, and a third portion whose outer radius is equal to the outer radius of the second portion, with the second portion, the first portion, and the third portion arranged in this order along the central axis. Heating coil.

2. The heating coil according to claim 1, A cooling means is provided, which is positioned at a distance from the heating coil in the first direction, and cools the workpiece heated by the heating coil. A moving means is provided that can change the positional relationship between the workpiece, the heating coil, and the cooling means between a first relationship in which a part of the workpiece is located within the first arc portion when viewed from the first direction, and a second relationship in which the second portion of the workpiece is separated from the first arc portion of the heating coil when viewed from the first direction, and also between the second relationship and a third relationship in which the workpiece can be cooled by the cooling means. A high-frequency induction hardening device.

3. The aforementioned means of transport is The heating coil is provided with a first movable part that can move between a position that realizes the first relationship and a position that realizes the second relationship, A second movable part that can move the workpiece between a position that realizes the second relationship and a position that realizes the third relationship, The high-frequency induction hardening apparatus according to claim 2, having the following features.

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