Induction heating coil and high frequency hardening device

Abstract

To provide an induction heating coil that can uniformly heat the entire inner wall of a metal member having a hemispherical depression and to provide a high-frequency hardening device including the same.SOLUTION: The induction heating coil is inserted into a hemispherical depression provided on a metal member to be heated. The induction heating coil has a configuration in which a plurality of arc-shaped first conductors 1, second conductors 3a, third conductors 3b, and fourth conductors 5 extending from the bottom to the top portion of an inner wall along the inner wall of the hemispherical depression is provided radially from the bottom to the top portion of the inner wall, and top ends of the plurality of conductors are connected by a fifth conductor 2 and a sixth conductor 4. The high-frequency hardening device uses the induction heating coil.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an induction heating coil, particularly an induction heating coil suitable for hardening the inner wall of a hemispherical recess provided in a metal member to be heated, and an induction hardening device using the induction heating coil. [Background technology]

[0002] Metallic components having a hemispherical depression on the inner circumference where a rolling surface such as a bearing ball is provided undergo heat treatment of quenching and tempering on the rolling surface to ensure the hardness of the rolling surface, and for this quenching, an induction heating coil is inserted into the hemispherical depression (a bowl-shaped hollow portion, a bowl-shaped body with a bottom) formed in the heated metallic component to heat it (see Patent Documents 1 and 2).

[0003] Patent Document 1 describes "an induction heating coil with multiple turns that is inserted into a bowl-shaped hollow portion formed in an object to be heated and rotates relatively to the object about a predetermined rotation axis, the induction heating coil comprising: a first conductor portion wound along the side wall of the bowl-shaped hollow portion with the boundaries between two adjacent turns of the multiple turns inclined at a predetermined angle within a range of less than 90° with respect to the predetermined rotation axis; and a second conductor portion continuing from the first conductor portion and extending along the bottom wall of the bowl-shaped hollow portion" (Claim 1). It also states that "in the first conductor portion 30, as described above, the boundary line 36 between the first turn 32 and the second turn 34 is inclined at an angle within a range of 75° to 82° with respect to the rotation axis 42, so that when the metal member 10 and the induction heating coil 20 are rotated relatively, "When the induction heating coil 20 is rotated relative to the metal member 10, the position of the portion of the side wall 14 of the metal member 10 facing the boundary line 36 moves from moment to moment, and no part of the side wall 14 goes unheated. As a result, all parts of the side wall 14 are heated evenly. Furthermore, because the second conductor 40 extends along the bottom wall 16, when the metal member 10 and the induction heating coil 20 are rotated relative to each other, the position of the portion of the bottom wall 16 facing the second conductor 40 moves from moment to moment, and all parts of the bottom wall 16 are heated evenly. Therefore, even if the wire diameter of the induction heating coil 20 is large and the hollow portion 12 is small, the side wall 14 of the hollow portion 12 can be heated by the first conductor 30 and the bottom wall 16 can be heated by the second conductor 40, and the side wall 14 and the bottom wall 16 can be heated evenly." (Paragraph

[0019] )

[0004] Patent Document 2 states that "the induction hardening apparatus 12 of this example shown in FIG. 4 comprises a workpiece holding jig 13 that holds an outer ring 4 having a bottomed, bowl-shaped socket portion 3 in a predetermined position; a high-frequency induction heating coil 14 that is disposed corresponding to the curved inner peripheral surface 3b of the socket portion 3 and that high-frequency induction heats this inner peripheral surface 3b; a gas introduction pipe (gas injection pipe) 15 that introduces an inert gas, a reducing gas, or a mixed gas of an inert gas and a reducing gas into the bottom 3a of the socket portion 3; a housing 16 that is disposed above the open mouth of the socket portion 3 held by the workpiece holding jig 13 and corresponds to the open mouth of the socket portion 3; a gas exhaust pipe 17 that exhausts gas that fills the housing 16 to the outside of the housing 16; a coolant injection pipe 18 that injects coolant onto the heated portion of the socket portion 3; and a gas supply pipe 19 that supplies the gas to the housing 16. and a coolant discharge pipe 19 that discharges the coolant that accumulates inside the workpiece 6 to the outside of the housing 16." (Paragraph

[0011] ), "The outer ring 4 is rotated together with the workpiece holding jig 13 by a workpiece rotation mechanism not shown." (Paragraph

[0012] ), "The high-frequency induction heating coil 14 is made of a copper pipe that can be water-cooled internally, and is wound in multiple layers along the shape of the workpiece to leave a required gap between it and the heated surface so that the recessed groove 8 of the receiving port portion 3 is induction heated in a non-contact state. The high-frequency induction heating coil 14 is configured so that a high-frequency current is appropriately supplied to it from a high-frequency power source 20 via coil leads 14a." (Paragraph

[0013] ).

[0005] Furthermore, induction heating coils having shapes different from the wound induction heating coils described in Patent Documents 1 and 2 are known (see Patent Documents 3 and 4).

[0006] Patent Document 3 describes an induction heating coil for an irregular-shaped cylindrical member, characterized in that "three conductors are arranged in the axial direction along the outer circumferential shape of the irregular-shaped cylindrical member, and are shaped to form a predetermined gap between them and the surface of the member to be treated, and one end of the three conductors is connected to each other, and the other ends of the two conductors on both sides are connected to each other, and a power source is connected to the lead portion of the other end of the central conductor and the lead portion where the other ends of the two conductors on both sides are connected to each other, forming a three-legged coil." (Claim 1). It also states that "In Figure 1, the three conductors 11, 12, and 13 of the heating coil 10 are conductors bent into a curved shape that forms a predetermined gap between them and the surface of the workpiece W, and The document states, "The conductors 11, 13 are arranged extending in the axial direction along the conductor line. Their one ends 11a, 12a, 13a are connected by a semicircular conductor 14." (Paragraph

[0015] ), and "Meanwhile, the other ends 11b, 13b of the two conductors 11 and 13 on both sides are connected by a semicircular conductor 15, and a lead portion 16 is connected to approximately the center of the conductor 15. A lead portion 17 is connected to the other end 12b of the central conductor 12, and both lead portions are drawn out in parallel with an insulator 18 sandwiched between the lead portion 17 and the lead portion 16. The lead portion 17 and the lead portion 16 are connected to a power source (not shown), forming a three-legged coil 10." (Paragraph

[0016] ).

[0007] Patent Document 4 states, "In a high-frequency induction heating coil body for high-frequency induction heating the outer peripheral surface of a shaft-shaped member having a plurality of different-diameter outer peripheral portions or the inner peripheral surface of a cylindrical member having a different-diameter inner peripheral portion, (a) first, second, third, and fourth heating conductors, each having a linear portion arranged parallel to the axial direction of the shaft-shaped member or the cylindrical member and facing the outer peripheral surface of the shaft-shaped member or the inner peripheral surface of the cylindrical member; (b) a first annular connecting conductor to which one ends of the first, second, third, and fourth heating conductors are respectively connected; (c) an annular second connecting conductor for connecting one of a pair of power supply lead portions connected to a high-frequency power supply to the other end of each of the first and second heating conductors among the four first, second, third, and fourth heating conductors; (d) a third connecting conductor having an arc shape for connecting the other of the pair of power supply lead portions to two of the first, second, third, and fourth heating conductors, namely, the third and fourth heating conductors, respectively; " (Claim 1) and further, "As shown in FIG. 1, the structure is formed by connecting conductive pipe materials, for example, having a rectangular cross section, to form a predetermined shape, and includes first to fourth heating conductors 22, 23, 24, 25 (hereinafter, these heating conductors 22 to 25 are mainly composed of the linear portions, and therefore will be referred to as the linear first to fourth heating conductors 22, 23, 24, 25) which are arranged parallel to the axial direction of the inner shaft 21, which is the part to be tempered, and which have linear portions arranged opposite the outer circumferential surface 21a of the inner shaft 21. "It is composed of an annular first connecting conductor 26 to which all of the one ends (lower ends in Fig. 1) of the heating conductors 22 to 25 are connected, an annular second connecting conductor 27 and an arc-shaped third connecting conductor 28 to which two of the other ends (upper ends in Fig. 1) opposite to the one ends of the heating conductors 22 to 25 are respectively connected, a first power supply lead part 30 connected between the second connecting conductor 27 and the high-frequency power source 29, and a second power supply lead part 31 connected between the second connecting conductor 28 and the high-frequency power source 29." (Paragraph

[0011] ) [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 11-26150 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-297718 [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-167618 [Patent Document 4] Patent No. 3733089 Summary of the Invention [Problem to be solved by the invention]

[0009] When hardening a non-heated metal part without moving it using a wound induction heating coil as described in Patent Documents 1 and 2, the metal part to be heated and the induction heating coil are rotated relative to each other in order to uniformly heat the inner wall of the hemispherical depression in the metal part to be heated, but this is not sufficient to achieve uniform heating.

[0010] Furthermore, induction heating coils that are not wound but have multiple conductors connected together are also known (see Patent Documents 3 and 4), but the induction heating coil described in Patent Document 3 has three conductors arranged along the outer periphery of an irregularly shaped cylindrical member, and there is no mention of inserting them into a hemispherical recess.The induction heating coil described in Patent Document 4 has four heating conductors, but linear portions form the majority of the coil, and there is no mention of forming the heating conductors to fit along the inner wall of a hemispherical recess.

[0011] Therefore, an object of the present invention is to provide an induction heating coil that can uniformly heat the entire inner wall of a hemispherical recess provided in a metal member to be heated, and an induction hardening device that uses such an induction heating coil. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention employs the following means. (1) An induction heating coil that is inserted into a hemispherical recess provided in a metal member to be heated, in which a plurality of arc-shaped conductors extending from the bottom to the top of the inner wall of the hemispherical recess are arranged radially from the bottom to the top so as to follow the inner wall of the hemispherical recess, and the plurality of conductors are connected to each other. (2) An induction hardening device for induction hardening the inner wall of a hemispherical depression formed in a heated metal member, the induction hardening device comprising the induction heating coil described in (1) and hardening the inner wall of the hemispherical depression while rotating the heated metal member and the induction heating coil relative to each other. [Effects of the Invention]

[0013] In the present invention, the induction heating coil inserted into a hemispherical depression provided in the metal member to be heated has multiple conductors arranged along the inner wall of the hemispherical depression, which has the effect of allowing the entire inner wall of the hemispherical depression to be heated uniformly and also to be hardened uniformly. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective conceptual diagram of an induction heating coil according to one embodiment of the present invention. [Figure 2] FIG. 2 is a conceptual perspective view of a metal member according to one embodiment of the present invention. [Figure 3] FIG. 3 is a conceptual front view of an induction hardening device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] (induction heating coil) In an embodiment of the present invention, the induction heating coil for hardening is an induction heating coil that is inserted into a hemispherical recess provided in a metal member to be heated, and multiple arc-shaped conductors that extend from the bottom to the top of the inner wall of the hemispherical recess are arranged radially from the bottom to the top so as to follow the inner wall of the hemispherical recess, and the multiple conductors are connected together. In this way, since multiple arc-shaped conductors extending from the bottom to the top of the inner wall of the hemispherical depression are arranged radially from the bottom to the top, the entire inner wall of the hemispherical depression provided in the heated metal member can be uniformly heated and can also be uniformly quenched.

[0016] The number of the arc-shaped conductors is preferably four or more. By providing four or more arc-shaped conductors extending from the bottom to the top, the entire inner wall of the hemispherical recess can be heated and quenched more uniformly.

[0017] An induction heating coil according to one embodiment of the present invention (hereinafter referred to as "this embodiment") will be described with reference to FIG.

[0018] (heating coil part) The heating coil portion of the induction heating coil 9 of this embodiment is provided with a first conductor 1 extending in an arc from the bottom to the top of the inner wall of a hemispherical depression provided in the metal member to be heated, a second conductor 3a and a third conductor 3b each extending in an arc from the bottom to the top away from the first conductor 1 (the second conductor 3a and the third conductor 3b are connected to each other at their lower ends on the bottom side of the inner wall of the depression), and a fourth conductor 5 extending in an arc from the bottom to the top away from the first conductor 1, the second conductor 3a and the third conductor 3b.

[0019] The four conductors, the first conductor 1, the second conductor 3a, the third conductor 3b and the fourth conductor 5, which extend in an arc shape from the bottom to the top, are arranged radially from the bottom to the top of the inner wall so as to follow the inner wall of the hemispherical recess. The upper ends of adjacent first and second conductors 1 and 3a among the conductors are connected by a horizontal fifth conductor 2, and the upper ends of adjacent third and fourth conductors 3b and 5 among the conductors are connected by a horizontal sixth conductor 4. In other words, the multiple conductors 1, 2, 3a, 3b, 4, and 5 are connected in this order in a single stroke to form a heating coil section. It is preferable that the horizontal fifth conductor 2 and sixth conductor 4 are arranged in an arc shape as shown in Figure 1, with a virtual line extending linearly from the bottom to the top of the inner wall of the recess as its center point, starting from the connection position of the second conductor 3a and the third conductor 3b, which are connected to each other at the lower end on the bottom side of the inner wall of the recess. Such an arc-shaped configuration is preferable because it makes it easier to arrange the lead portions described later.

[0020] (Lead part) In this embodiment, a first lead portion 6 (6a, 6b) extending linearly from the bottom of the inner wall of the recess toward the top is connected to the lower end of the first conductor 1, and a second lead portion 7 (7a, 7b) extending linearly from the bottom of the inner wall of the recess toward the top is connected to the lower end of the fourth conductor 5. The first lead portion 6b and the second lead portion 7b are drawn out in parallel with an insulator 8 sandwiched between them, thereby forming an induction heating coil 9 of four conductors 1, 3a, 3b, and 5. 6a and 6b of the first lead portion 6 are connected, and 7a and 7b of the second lead portion 7 are also connected. The first lead portion 6b and the second lead portion 7b are each connected to a power source (not shown). That is, the first lead portion 6, the multiple conductors 1, 2, 3a, 3b, 4, 5, and the second lead portion 7 are connected in this order in a single stroke to form the induction heating coil 9. Because the induction heating coil 9 is thus configured in a single stroke, it is easy to connect to a power source and to install the coil.

[0021] (Current flow to induction heating coil) In this embodiment, when high-frequency power is supplied to the induction heating coil 9, at one instant a high-frequency current flows in the induction heating coil 9 along a path indicated by arrow R in Fig. 1, and at the next instant a high-frequency current alternately flows along a path in the opposite direction to the direction of arrow R. Specifically, the high-frequency current flows sequentially from the first power supply lead part 6 to the arc-shaped first conductor 1, the horizontal fifth conductor 2, the arc-shaped second conductor 3a, the arc-shaped third conductor 3b, the horizontal sixth conductor 4, the arc-shaped fourth conductor 5, and the second power supply lead part 7, and then sequentially in the reverse direction.

[0022] (Other configurations of induction heating coils) The induction heating coil 9 is made of copper, for example. The induction heating coil 9 has a flow path through which a coolant flows to cool the induction heating coil 9 itself. To cool the induction heating coil 9 itself, a coolant supply means (not shown) injects coolant into an inlet at the upper end of the first lead portion 6a. The coolant flows through the arc-shaped first conductor 1, the horizontal fifth conductor 2, the arc-shaped second conductor 3a, the arc-shaped third conductor 3b, the horizontal sixth conductor 4, and the arc-shaped fourth conductor 5, and is discharged from an outlet at the upper end of the second lead portion 7a and collected.

[0023] (Heated metal member having a hemispherical recess) The induction heating coil of this embodiment is used to harden the inner wall of a metal member to be heated, which has a hemispherical recess as shown in FIG. The hemispherical depression formed in the heated metal member does not have to be half spherical, and may be shallower than half spherical. Conversely, it may be deeper than half spherical. The metal member is preferably a steel member, and as the steel member, for example, carbon steel can be used.

[0024] (High frequency hardening equipment) An induction hardening device for induction hardening the inner wall of a hemispherical depression in a heated metal member 10 (hereinafter referred to as metal member 10) has the depression, and is equipped with the above-mentioned induction heating coil 9, and hardens the inner wall of the hemispherical depression with the induction heating coil 9 while rotating the metal member 10 and the induction heating coil 9 relative to each other.

[0025] The configuration of the induction hardening device 15 according to this embodiment is shown in FIG. A metal member 10 having a hemispherical depression is fixed and placed on a rod-shaped member 11a of a turntable 11 for rotating the metal member 10 by a fixing means not shown, and the turntable 11 is fixed on a base 12 so that it can move up and down and rotate freely. The induction heating coil 9 is disposed above the metal member 10. The metal member 10 is placed on the rod-shaped member 11a of the turntable 11 with the hemispherical depression facing up, and the turntable 11 is raised so that the induction heating coil 9 is positioned along the inner wall of the hemispherical depression in the metal member 10 with a required gap between the inner wall, which is the heated surface. Conversely to the above, instead of moving the turntable 11 up and down, the induction heating coil 9 may be moved up and down.

[0026] A cooling jacket 13 is arranged between the inside of the heating coil portion of the induction heating coil 9 and the lead portions 6, 7 to cool the induction heating coil 9 from the outside and also to cool (rapidly cool) the inside of the hemispherical recess of the metal member 10. The cooling jacket 13 may be arranged on the outside of the induction heating coil 9. Cooling liquid is supplied to the cooling jacket 13 from a pipe 13a, and the cooling liquid is discharged from a cooling liquid supply hole (not shown) provided at the lower end of the cooling jacket 13 located above the heating coil portion of the induction heating coil 9, rapidly cooling the heating coil portion and the inner wall of the hemispherical depression in the high-frequency heated metal member 10.

[0027] When the inner wall of the hemispherical cavity of the metal member 10 is hardened using the induction hardening device 15, the following method is used. Metal member 10 is placed on turntable 11 with the hemispherical depression facing up, induction heating coil 9 is inserted into the hemispherical depression, and while metal member 10 is rotated about a rotation axis passing through the center of the bottom wall of the hemispherical depression, the inner walls (bottom wall and side wall) are heated to a predetermined temperature for high-frequency induction heating, and then coolant is supplied from cooling jacket 13 to the inner walls of the hemispherical depression in metal member 10 to rapidly cool and harden them. As a result, the inner walls of the hemispherical depression are heated uniformly to a uniform depth at all positions, and a hardened layer of uniform depth is obtained on the inner walls of the hemispherical depression.

[0028] The induction hardening device 15 according to this embodiment is preferably provided with a cooling device 14 for injecting a coolant from the top of the turntable 11 (below the metal member 10) to cool the opposite side of the metal member 10 during high-frequency induction heating of the hemispherical depression or during quenching cooling during rapid cooling. That is, it is preferable to provide coolant injection holes 14a in the rotary table 11, connect a hose or the like (not shown) to the rotary table 11 to supply the coolant, and inject the coolant from the injection holes 14a. In this way, by providing a cooling device 14 that cools the opposite side of the inner wall of the hemispherical depression in the metal member 10 while the inner wall is being induction heated, the hardening depth of the inner wall and the heat amount of the metal member 10 can be controlled.

[0029] In the above-described high-frequency hardening device 15, the metal member 10 is placed on the bottom and the induction heating coil 9 is placed on the top, but it is also possible to reverse the top and bottom and place the metal member on top and the induction heating coil on the bottom, as shown in Patent Document 1. In this embodiment, when the metal member is placed on top and the induction heating coil is placed on the bottom, the bottom of the induction heating coil 9 becomes the top, the top becomes the bottom, the top end becomes the bottom end, and the bottom end becomes the top end. In the above case, a cooling device for rapidly cooling the metal member is also provided on the upper part.

[0030] Furthermore, the induction hardening device according to the present invention is not limited to the structure shown in FIG. 3 and can have a wide variety of structures as long as it is equipped with an induction heating coil and can harden the inner wall of the hemispherical recess while rotating the heated metal member and the induction heating coil relative to each other. [Industrial Applicability]

[0031] By using the induction heating coil of the present invention for induction hardening, the inner wall of a metal member (especially a steel member) having a hemispherical depression can be uniformly heated and uniformly hardened, so the induction heating coil can be effectively used for induction hardening of metal members (especially steel members) whose inner wall of the depression needs to be hardened. [Explanation of symbols]

[0032] 1: An arc-shaped conductor (first conductor) extending from one point at the bottom to the top 2: A horizontal conductor (fifth conductor) connecting the upper end of the first conductor 1 and the upper end of the second conductor 3a 3a: A part of the conductor 3, an arc-shaped conductor portion (second conductor) extending from a point at the bottom away from the conductor 1 toward the top 3b: An arc-shaped conductor portion (third conductor) extending from a point at the bottom away from the first conductor 1 toward the top in the opposite direction to the second conductor 3a 4: A horizontal conductor (sixth conductor) connecting the upper end of the third conductor 3b and the upper end of the fourth conductor 5 5: An arc-shaped conductor (fourth conductor) extending from one point at the bottom to the top 6 (6a, 6b): Lead portion (first lead portion) connected to the lower end of the conductor 1 and extending in the axial direction 7 (7a, 7b): Lead portion (second lead portion) connected to the lower end of the conductor 5 and extending in the axial direction 8: Insulator 9: Induction heating coil 10: Heated metal member 11: Rotating table 11a: Rod-shaped member 12: Base 13: Cooling jacket 13a: Coolant supply pipe 14: Cooling device 14a: Cooling water injection hole 15: High frequency hardening equipment

Claims

1. An induction heating coil is inserted into a hemispherical recess provided in a metal member to be heated, and four conductors, namely a first conductor 1, a second conductor 3a, a third conductor 3b, and a fourth conductor 5, are arranged radially from the bottom to the top of the inner wall of the hemispherical recess, and extend from the bottom to the top of the inner wall (however, the second conductor 3a and the third conductor 3b are connected at their lower ends on the bottom side of the inner wall), so as to follow the inner wall of the hemispherical recess. The upper ends of adjacent first conductor 1 and second conductor 3a are connected by a horizontal fifth conductor 2, and the upper ends of adjacent third conductor 3b and fourth conductor 5 are connected by a horizontal sixth conductor 4.

2. 10. An induction hardening apparatus for induction hardening the inner wall of a hemispherical recess formed in a metal member to be heated, comprising the induction heating coil according to claim 1, and hardening the inner wall of the hemispherical recess while rotating the metal member to be heated and the induction heating coil relative to each other.

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