JP2003313611A - Process and tool for heat treatment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat treatment process wherein corners of a member having a through-hole are heated to a predetermined temperature. <P>SOLUTION: A plate 10 is placed almost horizontally, and a heat-treatment tool 20 is fixed onto the plate 10 by inserting a rod-like part 22 of the heat- treatment tool 20 into the through-hole 16 from above (i.e., from the other surface 14) and nipping the plate 10 from both sides 18a and 18b with a pair of retaining claws 24a. This places the rod-like part 22 in a manner avoiding contact with the through-hole 16, with a gap t between the rod-like part 22 and the through-hole 16 of about 0.5 mm. In this state, an induction heating coil 30 is brought close to a surface 12 of the plate 10 to perform induction heating of the surface 12 to a predetermined quenching temperature while spraying a coolant 32 onto the through-hole 16 from above (i.e., from the other surface 14). <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment method for heat treating a member (workpiece) having a through hole, and a heat treatment jig used in this heat treatment.

[0002]

2. Description of the Related Art Conventionally, induction hardening has been widely used in which induction heating is used to heat a metal object to be heated (work) and quench it to harden it. As one of the works to be subjected to the induction hardening, there is a member having a hole (through hole) formed from one surface to the other surface. In a member having a through hole, for example, the peripheral portion of the through hole (or the entire one surface) of one surface may be quenched. When quenching, the peripheral part (or the entire one surface) is induction-heated to the quenching temperature and quenched. In this case, the corner portion formed by the peripheral portion to be induction-heated and the through hole (the portion surrounded by both the inner surface of the entrance / exit portion of the through-hole and the surface of the peripheral portion continuous with the inner surface) is also induction-heated. However, this corner may be heated above the quenching temperature. When the temperature of the corner increases too much, the corner may melt.

[0003]

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a heat treatment method and a heat treatment jig for heating a corner portion of a member having a through hole to a predetermined temperature.

[0004]

A first heat treatment method of the present invention for achieving the above object is a heat treatment method for heat treating a member having a through hole penetrating from one surface to the other surface, (1) At least the peripheral portion of the through hole of both the one surface and the other surface or any one of the surfaces is induction-heated to a predetermined temperature, and the induction-heated peripheral portion and The corner portion formed by the through hole is also induction-heated so as to reach the predetermined temperature.

Here, (2) when the corner portion is induction-heated to reach the predetermined temperature, the peripheral portion may be induction-heated while cooling the corner portion.

Further, (3) a jig having an outer diameter smaller than the inner diameter of the through hole is inserted into the through hole so as not to come into contact with the inner surface of the through hole and arranged near the corner.
(4) When the peripheral portion is induction-heated while cooling the corner portion, a cooling liquid may be injected into the through hole to cool the corner portion.

The second heat treatment method of the present invention for attaining the above object is the heat treatment method of heat treating in water a member having through-holes penetrating from one surface to the other surface. ) When inductively heating at least the peripheral portion of the through hole of both the one surface and the other surface or any one of the surfaces to (6) an outer diameter smaller than the inner diameter of the through hole. A jig having a diameter is inserted into the through hole so as not to come into contact with the inner surface of the through hole, and the jig is arranged near a corner formed by the through hole and the peripheral portion to be induction-heated. It is characterized by setting.

The third heat treatment method of the present invention for attaining the above object is the heat treatment method of induction hardening a member having a through hole penetrating from one surface to the other surface. At least the peripheral portion of the through hole of at least one of the one surface and the other surface or one of the surfaces is induction-heated to a predetermined quenching temperature, and the peripheral portion to be induction-heated is The corners formed by the through-holes are also induction-heated and quenched so as to reach the predetermined quenching temperature.

(8) When the corners are induction-heated to reach the predetermined quenching temperature, the peripheral parts may be induction-heated while cooling the corners.

Further, (9) a jig having an outer diameter smaller than the inner diameter of the through hole is inserted into the through hole so as not to contact the inner surface of the through hole and arranged in the vicinity of the corner. (1
0) When the peripheral portion is induction-heated while cooling the corner portion, a cooling liquid may be injected into the through hole to cool the corner portion.

A fourth heat treatment method of the present invention for attaining the above object is the heat treatment method of induction hardening in water a member having a through hole penetrating from one surface to the other surface, which is (11) A jig having an outer diameter smaller than the inner diameter of the through hole is inserted into the through hole so as not to come into contact with the inner surface of the through hole, and one or both of the one surface and the other surface The jig is arranged near at least a peripheral portion of the through hole and a corner formed by the through hole, and (12) the peripheral portion is induction-heated to a predetermined quenching temperature. It is characterized by hardening by quenching.

Further, a fifth heat treatment method of the present invention for achieving the above object is the heat treatment method for heat treating a cylindrical member having a through hole penetrating from an inner wall surface to an outer wall surface. Both the inner wall surface and the outer wall surface are induction-heated to a predetermined temperature, and both the corner portion formed by the inner wall surface and the through hole and the corner portion formed by the outer wall surface and the through hole are also the predetermined. It is characterized in that induction heating is performed so as to reach the temperature.

A sixth heat treatment method of the present invention for achieving the above object is the heat treatment method for heat treating a cylindrical member having a through hole penetrating from an inner wall surface to an outer wall surface. The inner wall surface is induction-heated so as to reach a predetermined temperature, and the corner portions formed by the inner wall surface and the through holes are also induction-heated so as to reach the predetermined temperature.

A seventh heat treatment method of the present invention for achieving the above object is the heat treatment method for heat treating a cylindrical member having a through hole penetrating from an inner wall surface to an outer wall surface. The outer wall surface is induction-heated to a predetermined temperature, and the corners formed by the outer wall surface and the through holes are also induction-heated to the predetermined temperature.

(16) When the corner portion is induction-heated to reach the predetermined temperature, the peripheral portion may be induction-heated while cooling the corner portion.

(17) A jig having an outer diameter smaller than the inner diameter of the through hole is inserted into the through hole so as not to come into contact with the inner surface of the through hole, and is placed near the corner.
(18) When the peripheral portion is induction-heated while cooling the corner portion, a cooling liquid may be jetted into the through hole to cool the corner portion.

The eighth heat treatment method of the present invention for attaining the above object is the heat treatment method of heat treating a cylindrical member having a through hole penetrating from an inner wall surface to an outer wall surface in water in water. ) A jig having an outer diameter smaller than the inner diameter of the through hole is inserted into the through hole so as not to contact the inner surface of the through hole, and the corner portion formed by the inner wall surface and the through hole and the outer wall surface. The jig is placed near both corners formed by the through hole and (20) the inner wall surface and the outer wall surface are induction-heated to a predetermined temperature.

Further, a ninth heat treatment method of the present invention for attaining the above object is the heat treatment method of heat treating a cylindrical member having a through hole penetrating from an inner wall surface to an outer wall surface in water, wherein (21) ) A jig having an outer diameter smaller than the inner diameter of the through hole is inserted into the through hole so as not to contact the inner surface of the through hole, and the jig is provided near the corner formed by the inner wall surface and the through hole. A jig is arranged and (22) the inner wall surface is induction-heated to a predetermined temperature.

The tenth heat treatment method of the present invention for attaining the above object is the heat treatment method of heat-treating a cylindrical member having through-holes penetrating from an inner wall surface to an outer wall surface in water, according to (23) ) A jig having an outer diameter smaller than the inner diameter of the through hole is inserted into the through hole so as not to contact the inner surface of the through hole, and the jig is provided near the corner formed by the outer wall surface and the through hole. A jig is arranged and (24) the outer wall surface is induction-heated to a predetermined temperature.

The eleventh heat treatment method of the present invention for attaining the above object is the heat treatment method for induction hardening a cylindrical member having a through hole penetrating from an inner wall surface to an outer wall surface. At least the peripheral portion of the through hole of both the inner wall surface and the outer wall surface or one of the wall surfaces is induction-heated to a predetermined quenching temperature, and the peripheral portion to be induction-heated and the penetration The corners formed by the holes are also induction-heated and quenched so as to reach the predetermined quenching temperature.

(26) When the corner portion is induction-heated to reach the predetermined quenching temperature, the peripheral portion may be induction-heated while cooling the corner portion.

(27) A jig having an outer diameter smaller than the inner diameter of the through hole is inserted into the through hole so as not to come into contact with the inner surface of the through hole, and is placed near the corner.
(28) When the peripheral portion is induction-heated while cooling the corner portion, a cooling liquid may be injected into the through hole to cool the corner portion.

A twelfth heat treatment method of the present invention for achieving the above object is the heat treatment method of induction hardening in water a cylindrical member having a through hole penetrating from an inner wall surface to an outer wall surface. 29) A jig having an outer diameter smaller than the inner diameter of the through hole is inserted into the through hole so as not to contact the inner surface of the through hole, and the corner portion formed by the inner wall surface and the through hole and the outer portion. The jig is arranged near both corners formed by the wall surface and the through hole, and (30) the inner wall surface and the outer wall surface are induction-heated to a predetermined quenching temperature for quenching. It is what

A thirteenth heat treatment method of the present invention for achieving the above object is the heat treatment method of induction hardening in water a cylindrical member having a through hole penetrating from an inner wall surface to an outer wall surface. 31) A jig having an outer diameter smaller than the inner diameter of the through hole is inserted into the through hole so as not to come into contact with the inner surface of the through hole, and near the corner formed by the inner wall surface and the through hole. Arrange the jig, (32)
The inner wall surface is induction-heated to a predetermined quenching temperature for quenching.

A fourteenth heat treatment method of the present invention for achieving the above object is a heat treatment method of induction hardening in water a cylindrical member having a through hole penetrating from an inner wall surface to an outer wall surface. 33) A jig having an outer diameter smaller than the inner diameter of the through hole is inserted into the through hole so as not to come into contact with the inner surface of the through hole, and near the corner formed by the outer wall surface and the through hole. Arrange the jig, (34)
The outer wall surface is induction-heated to a predetermined quenching temperature.

Further, the first heat treatment jig of the present invention for achieving the above object is a heat treatment used when heat-treating a member having a through hole penetrating from one surface to the other surface. (35) The jig for use has (35) an outer diameter smaller than the inner diameter of the through hole, and a rod-shaped portion that is inserted into the through hole so as not to contact the inner surface of the through hole. Is.

Further, a second heat treatment jig of the present invention for achieving the above object is a heat treatment used when heat-treating a cylindrical member having a through hole penetrating from an inner wall surface to an outer wall surface. (36) a rod-shaped portion having an outer diameter smaller than the inner diameter of the through hole; and (37) the rod-shaped portion inside the through hole so that the rod-shaped portion does not contact the inner surface of the through hole. It is characterized by comprising a holding unit for holding.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. [First Embodiment]

A first embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 is a perspective view showing a flat plate and a heat treatment jig which are induction hardened in the atmosphere. FIG. 2 is a sectional view showing a flat plate in which the rod-shaped portion of the heat treatment jig of FIG. 1 is inserted into the through hole.

A through hole 16 penetrating from one surface 12 to the other surface 14 is formed in the flat plate 10 (which is an example of a member having a through hole in the present invention). Here, a case where one surface 12 is induction hardened will be described. A heat treatment jig 20 (which is an example of a jig according to the invention) used when induction hardening one surface 12 is a rod-shaped portion 22 inserted into the through hole 16 and holds the rod-shaped portion 22. And a holding section 24 for

The rod-shaped portion 22 has an outer diameter smaller than the inner diameter of the through hole 16. The holding portion 24 extends from the root of the rod-shaped portion 22 almost orthogonally to the rod-shaped portion 22, and the through-hole 16
The rod-shaped portion 22 inserted in the above is held so as not to contact the inner surface of the through hole 16. A pair of holding claws 24 having elasticity (spring property) is provided at both ends in the longitudinal direction of the holding part 24.
a is formed and the flat plate 1 is formed by the pair of holding claws 24a.
Both side surfaces 18a and 18b of 0 are sandwiched. As a result, the heat treatment jig 20 is fixed to the flat plate 10, and the rod-shaped portion 22 is held so as not to contact the inner surface of the through hole 16. In addition, a hole 24b for passing the cooling liquid 32 is formed in a portion of the holding portion 24 in the vicinity of the connecting portion with the rod-shaped portion 22.

The pair of holding claws 24a is the upper surface 1 of the flat plate.
You may comprise so that 9a and the lower surface 19b may be pinched | interposed. Further, both side surfaces 18a, 18b and the upper surface 19a of the flat plate 10
Alternatively, two pairs of holding claws may be formed on the heat treatment jig 20 so as to sandwich both the lower surface 19b and the lower surface 19b.

In the above example, the through hole 16 has a cylindrical shape (having a circular cross section), but it may have a prismatic shape such as a triangle or a quadrangle (a cross section having a triangle or a quadrangle). Good. In this case, the rod-shaped portion 22 has a prismatic shape such as a triangle or a quadrangle according to the shape of the through hole 16.

A heat treatment method for induction hardening one surface 12 of the flat plate 10 using the above-mentioned heat treatment jig 20 will be described.

The flat plate 10 is arranged substantially horizontally, the rod portion 22 of the heat treatment jig 20 is inserted into the through hole 16 from above (from the other surface 14 side), and both side surfaces 18 of the flat plate 10 are inserted.
The heat treatment jig 20 is fixed to the flat plate 10 by sandwiching a and 18b with a pair of holding claws 24a. As a result, as shown in FIG. 2, the rod-shaped portion 22 is arranged so as not to contact the through hole 16. In this case, the gap t between the through hole 16 and the rod-shaped portion 22
Is about 0.5 mm.

In the state as described above, the induction heating coil 30 is brought close to one surface 12 of the flat plate 10 to induction-heat this surface 12 to a predetermined quenching temperature, and at the same time from above (on the side of the other surface 14). The cooling liquid 32 is injected into the through hole 16.
The jetted cooling liquid 32 passes through the hole 24b and the like, passes through the gap t, and drops from the surface 12 side. The corner portion 11 formed by the surface 12 and the through hole 16 is appropriately cooled by the cooling liquid 32. As a result, the corner portion 11 also has the same quenching temperature as the surface 12, and the corner portion 11 is not induction-heated above the quenching temperature. Therefore, the corner portion 11 does not melt.

Since the cooling liquid 32 drops almost directly below, the cooling liquid 32 hardly contacts the surface 12 (which is an example of the peripheral portion referred to in the present invention) during induction heating.
2 is not cooled by the cooling liquid 32. Therefore, face 12
And the corner portion 11 are both induction-heated to an appropriate quenching temperature. After the surface 12 and the corner portion 11 are heated to an appropriate quenching temperature, the cooling liquid is jetted from below toward the surface 12 so that the surface 1
A hardened layer is formed on the corner 2 and the corner 11. Surface 12 from below
When injecting the cooling liquid toward, the cooling liquid 32 is kept ejected from above the other surface 14 as well.

When quenching both the one surface 12 and the other surface 14, after quenching the surface 12 by the method described above,
The flat plate 10 is bent so that the surface 14 faces upward, and the surface 14 is quenched by the above method. Further, in the above example, quenching was described, but the above heat treatment method can also be applied to annealing and tempering. In this case, the surface 12 is heated to a predetermined annealing temperature or tempering temperature while cooling the corner portion 11 as described above. As a result, the surface 12 and the corner portion 11 are heated to a predetermined annealing temperature or tempering temperature. The heat treatment method is not limited to the flat plate 10 and can be applied to, for example, a curved plate. [Second Embodiment]

A second embodiment of the present invention will be described with reference to FIG.

FIG. 3 is a sectional view showing a flat plate and a heat treatment jig which are induction hardened in water. In FIG. 3, the same components as those shown in FIGS. 1 and 2 are designated by the same reference numerals.

A case where one surface 12 of the flat plate 10 is induction hardened in water will be described. The heat treatment jig 20 used in this induction hardening is the same as the heat treatment jig 20 of the first embodiment.

The bar portion 22 of the heat treatment jig 20 is inserted into the through hole 16 from the other surface 14 side, and the pair of holding claws 24a of the heat treatment jig 20 are used to form both side surfaces 18a and 18b of the flat plate 10.
And the heat treatment jig 20 is fixed to the flat plate 10. In this case, similarly to the first embodiment, the gap t between the through hole 16 and the rod-shaped portion 22 is maintained at about 0.5 mm, and the rod-shaped portion 22 is
Are not brought into contact with the through holes 16. The flat plate 10 to which the heat treatment jig 20 is fixed is fixed to the mounting table 33 of the container 30. The container 30 is filled with water 34.

In the above-mentioned state, the induction heating coil 40 is brought close to one surface 12 of the flat plate 10, and the induction heating coil 40 is supplied with appropriate high frequency power so that the surface 12 is hardened in a predetermined manner. Induction heating to temperature. The corner portion 11 is also heated by this induction heating. However, the through hole 16
Water 34 is filled in the gap t between the rod portion 22 and
Since the corner portion 11 is cooled by the filled appropriate amount of water 34, the corner portion 11 is not heated to a temperature higher than a predetermined quenching temperature. Therefore, the corner portion 11 does not melt. In addition, when the heat treatment jig 20 is not used, all of the through holes 16 are filled with water 34, and the corner portion 1
1 is overcooled. Therefore, even if the surface 12 reaches the predetermined quenching temperature, the corner portion 11 does not reach the predetermined quenching temperature.
Therefore, the above-mentioned gap t is set so that the corner portion 11 has a predetermined quenching temperature.

After induction heating of the surface 12 and the corner portion 11 to a predetermined quenching temperature as described above, the high frequency power supplied to the induction heating coil 40 is stopped. Since the surface 12 and the corner portion 11 are in contact with the water 34, they are rapidly cooled.
A hardened layer is formed on the corner 2 and the corner 11.

When quenching both the one surface 12 and the other surface 14, after quenching the surface 12 by the above-described method, the rod portion 22 of the heat treatment jig 20 is inserted from the one surface 12 side. The pair of holding claws 24a of the heat treatment jig 20.
The both sides 18a, 18b of the flat plate 10 are sandwiched by and the heat treatment jig 20 is fixed to the flat plate 10. After that, surface 1
It is similar to the procedure for quenching No. 2. Also, face 12 and face 1
4 is simultaneously quenched, use a jig for heat treatment in which the portion other than the rod-shaped portion 22 is as small as possible.
Is inserted into the through hole 16 and the surfaces 12 and 14 are heated at the same time.

In the above example, quenching was described, but the heat treatment method described above can also be applied to annealing and tempering. In this case, the surface 12 is heated to a predetermined annealing temperature or tempering temperature while cooling the corner portion 11 as described above. As a result, the surface 12 and the corner portion 11 are heated to a predetermined annealing temperature or tempering temperature. The heat treatment method is not limited to the flat plate 10 and can be applied to, for example, a curved plate. [Third Embodiment]

A third embodiment of the present invention will be described with reference to FIGS. 4 and 5.

FIG. 4 is a perspective view showing a cylindrical member and a heat treatment jig which are induction hardened in the atmosphere. FIG. 5 is a sectional view showing a cylindrical member in which the rod-shaped portion of the heat treatment jig of FIG. 4 is inserted into the through hole.

The cylindrical member 50 has two through holes 56 penetrating from the inner wall surface 52 to the outer wall surface 54. Here, a case where the inner wall surface 52 of the cylindrical member 50 is induction hardened will be described. A heat treatment jig 60 (which is an example of a jig according to the invention) used when induction hardening the inner wall surface 52 holds a rod-shaped portion 62 inserted into the through hole 56 and the rod-shaped portion 62. And a holding portion 64.

The rod portion 62 has an outer diameter smaller than the inner diameter of the through hole 56. The holding portion 64 extends from the root of the rod-shaped portion 62 almost orthogonally to the rod-shaped portion 62, and has a through hole 56.
The rod-shaped portion 62 inserted in the above is held so as not to contact the inner surface of the through hole 56. A pair of holding claws 64a having elasticity (spring property) is formed in the holding portion 64, and the outer wall surface 54 of the cylindrical member 50 is sandwiched by the pair of holding claws 64a. As a result, the heat treatment jig 60 is fixed to the cylindrical member 50, and the rod-shaped portion 62 is formed in the through hole 5.
It is held so as not to contact the inner surface of 6. In addition, a hole 64 b for passing the cooling liquid 32 is formed in a portion of the holding portion 64 near the connecting portion with the rod-shaped portion 62.

In the above-mentioned example, the through hole 56 has a cylindrical shape (having a circular cross section), but it may have a prismatic shape such as a triangle or a quadrangle (a cross section having a triangle or a quadrangle). Good. In this case, the rod-shaped portion 62 has a prismatic shape such as a triangle or a quadrangle according to the shape of the through hole 56.

A heat treatment method of induction hardening the inner wall surface 52 of the cylindrical member 50 using the above-described heat treatment jig 60 will be described.

The cylindrical member 50 is placed upright, and the rod portion 62 of the heat treatment jig 60 is penetrated from the outer wall surface 54 side to the through hole 56.
And the cylindrical member 50 with the pair of holding claws 64a.
The heat treatment jig 60 is fixed to the cylindrical member 50 by sandwiching the outer wall surface 54 thereof. Thereby, as shown in FIG. 5, the rod-shaped portion 62 is arranged so as not to contact the through hole 56.
In this case, the clearance t between the through hole 56 and the rod-shaped portion 62 is about 0.
It becomes 5 mm.

In the above state, the induction heating coil 70 (which also serves as a cooling jacket for injecting a cooling liquid) is inserted into the hollow portion of the cylindrical member 50 so that the induction heating coil 70 approaches the inner wall surface 52. Let In this state, appropriate high-frequency power is supplied to the induction heating coil 70 to induction-heat the inner wall surface 52 to a predetermined quenching temperature, and the cooling liquid 32 is jetted from the outer wall surface 54 side to the through hole 56. The cooling liquid 32 enters the through holes 56 through the holes 64b and the like, and the inner wall surface 52
The corner portion 58 formed by the through hole 56 and the through hole 56 is appropriately cooled. As a result, the corner portion 58 also has the same quenching temperature as the inner wall surface 52, and the corner portion 58 is not induction-heated above the quenching temperature. Therefore, the corner portion 58 does not melt. Therefore,
Both the inner wall surface 52 and the corner portion 58 are induction-heated to an appropriate quenching temperature. After the inner wall surface 52 and the corner portion 58 are heated to an appropriate quenching temperature, the induction heating coil 70 injects a cooling liquid toward the inner wall surface 52 to form a hardened layer on the inner wall surface 52 and the corner portion 58. It is formed. When the cooling liquid is sprayed from the induction heating coil 70 toward the inner wall surface 52, the cooling liquid 32 is kept sprayed from the outer wall surface 54 side to the through hole 56.

In the above example, quenching was described, but the heat treatment method described above can also be applied to annealing and tempering. In this case, the inner wall surface 52 is heated to a predetermined annealing temperature or tempering temperature while cooling the corner portion 58 as described above. As a result, the inner wall surface 52 and the corner portion 58 are heated to a predetermined annealing temperature or tempering temperature. The heat treatment method is not limited to the cylindrical member 50 and may be applied to, for example, a prism. [Fourth Embodiment]

A fourth embodiment of the present invention will be described with reference to FIG.

FIG. 6 is a sectional view showing a cylindrical member and a heat treatment jig which are induction hardened in water. In FIG. 6, the same components as those shown in FIGS. 4 and 5 are designated by the same reference numerals.

A case where the inner wall surface 52 of the cylindrical member 50 is induction hardened in water will be described. The heat treatment jig 60 used in this induction hardening is the same as the heat treatment jig 60 of the third embodiment.

The rod-shaped portion 62 of the heat treatment jig 60 is attached to the outer wall surface 5.
4 side, and a pair of holding claws 6 of the heat treatment jig 60.
The outer wall surface 54 of the cylindrical member 50 is sandwiched by 4a, and the heat treatment jig 60 is fixed to the cylindrical member 50. In this case, similarly to the third embodiment, the gap t between the through hole 56 and the rod-shaped portion 62 is maintained at about 0.5 mm, and the rod-shaped portion 62 is inserted into the through hole 56.
Do not come into contact with. The cylindrical member 50 to which the heat treatment jig 60 is fixed is fixed to the mounting table 33 of the container 30. Container 30
It is filled with water 34.

In the above-mentioned state, the induction heating coil 80 is brought close to the inner wall surface 52 of the cylindrical member 50, and an appropriate high frequency power is supplied to the induction heating coil 80 so that the inner wall surface 52 has a predetermined shape. Induction heating to quenching temperature. The corner portion 58 is also heated by this induction heating. However, the gap t between the through hole 56 and the rod-shaped portion 62 is filled with water 34, and the corner portion 58 is cooled by the filled appropriate amount of water 34. It is not heated above the temperature. Therefore, the corner portion 58 does not melt. Note that when the heat treatment jig 60 is not used, the through holes 56 are all filled with water 34, and the corner portions 58 are cooled too much. Therefore, the inner wall surface 52
Even if the temperature reaches a predetermined hardening temperature, the corner portion 58 does not reach the predetermined hardening temperature. Therefore, the above-mentioned gap t is set so that the corner portion 58 has a predetermined quenching temperature.

After induction heating the inner wall surface 52 and the corner portion 58 to a predetermined quenching temperature as described above, the induction heating coil 80
Stop the high frequency power supplied to. Since the inner wall surface 52 and the corner portion 58 are in contact with the water 34, they are rapidly cooled, and a hardened layer is formed on the inner wall surface 52 and the corner portion 58.

Although quenching has been described in the above example, the heat treatment method described above can be applied to annealing and tempering. In this case, the inner wall surface 52 is heated to a predetermined annealing temperature or tempering temperature while cooling the corner portion 58 as described above. As a result, the inner wall surface 52 and the corner portion 58 are heated to a predetermined annealing temperature or tempering temperature. [Fifth Embodiment]

A fifth embodiment of the present invention will be described with reference to FIGS. 7 and 8.

FIG. 7 is a perspective view showing a cylindrical member and a heat treatment jig which are induction hardened in the atmosphere. FIG. 8 is a cross-sectional view showing a cylindrical member in which the rod-shaped portion of the heat treatment jig of FIG. 7 is inserted into the through hole. In these figures, the same components as those shown in FIGS. 4 and 5 are designated by the same reference numerals.

Here, a case where the outer wall surface 54 of the cylindrical member 50 is induction hardened will be described. A heat treatment jig 90 (which is an example of a jig according to the invention) used when induction hardening the outer wall surface 54 holds a rod-shaped portion 92 inserted into the through hole 56 and the rod-shaped portion 92. Holding part 9
4 and.

The rod portion 92 has an outer diameter smaller than the inner diameter of the through hole 56. The holding portion 94 holds the rod-shaped portion 92 inserted into the through hole 56 so as not to contact the inner surface of the through hole 56. The holding portion 94 is formed with a pair of holding claws 94a having elasticity (spring property), and the upper end surface 50a and the lower end surface 50b of the cylindrical member 50 are sandwiched by the pair of holding claws 94a. Thereby, the heat treatment jig 9
0 is fixed to the cylindrical member 50, and the rod-shaped portion 92 is held so as not to contact the inner surface of the through hole 56.

In the above-mentioned example, the through hole 56 has a cylindrical shape (having a circular cross section), but it may have a prismatic shape such as a triangle or a quadrangle (a cross section having a triangle or a quadrangle). Good. In this case, the rod-shaped portion 92 has a prismatic shape such as a triangle or a quadrangle according to the shape of the through hole 56.

A heat treatment method for induction hardening the outer wall surface 54 of the cylindrical member 50 using the above-described heat treatment jig 90 will be described.

The cylindrical member 50 is placed upright, and the rod-shaped portion 92 of the heat treatment jig 90 is inserted into the through hole 56 from the inner wall surface 52 side.
And the cylindrical member 50 with the pair of holding claws 94a.
The heat treatment jig 90 is fixed to the cylindrical member 50 by sandwiching the upper end surface 50a and the lower end surface 50b thereof. As a result, FIG.
As shown in, the rod-shaped portion 92 is arranged so as not to contact the through hole 56. In this case, the gap t between the through hole 56 and the rod-shaped portion 92 is about 0.5 mm.

In the state as described above, the cooling jacket 100 is inserted into the hollow portion of the cylindrical member 50, and the induction heating coil (which also serves as the cooling jacket for injecting the cooling liquid) 110 is brought close to the outer wall surface 54. Induction heating coil 11
0 is supplied with high frequency power to inductively heat the outer wall surface 54 to a predetermined quenching temperature, and the cooling liquid 100 is jetted from the cooling jacket 100 to the inner wall surface 52. The cooling liquid 102 enters the through holes 56 and cools the corners 59 formed by the outer wall surface 54 and the through holes 56.
The quenching temperature is the same as that of No. 4, and the corner portion 59 is not induction-heated above this quenching temperature. Therefore, the corner portion 59 does not melt. Therefore, both the outer wall surface 54 and the corner portion 59 are induction-heated to an appropriate quenching temperature. In addition, the shape of the holding portion 94 is the cooling liquid 102 sprayed from the cooling jacket 100.
Has a shape that does not prevent the entry of the into the through hole 56.

After the outer wall surface 54 and the corner portion 59 are heated to an appropriate quenching temperature, the induction heating coil 110 injects the cooling liquid toward the outer wall surface 54, whereby the outer wall surface 54 and the corner portion 59 are A hardened layer is formed. When the cooling liquid is jetted from the induction heating coil 110 toward the outer wall surface 54, the cooling liquid 102 is kept jetted from the cooling jacket 100 to the inner wall surface 52.

Although quenching is described in the above example, the heat treatment method described above can also be applied to annealing and tempering. In this case, the outer wall surface 54 is heated to a predetermined annealing temperature or tempering temperature while cooling the corner portion 59 as described above. As a result, the outer wall surface 54 and the corner portion 59 are heated to a predetermined annealing temperature or tempering temperature. The heat treatment method is not limited to the cylindrical member 50 and may be applied to, for example, a prism. [Sixth Embodiment]

A sixth embodiment of the present invention will be described with reference to FIG.

FIG. 9 is a sectional view showing a cylindrical member and a heat treatment jig which are induction hardened in water. In FIG. 9, the same components as those shown in FIGS. 7 and 8 are designated by the same reference numerals.

A case where the outer wall surface 54 of the cylindrical member 50 is induction hardened in water will be described. The heat treatment jig 90 used in the induction hardening is the same as the heat treatment jig 90 of the fifth embodiment.

The rod-shaped portion 92 of the heat treatment jig 90 is attached to the inner wall surface 5.
2 is inserted into the through hole 56 and the heat treatment jig 90 is fixed to the cylindrical member 50 by sandwiching the upper end surface 50a and the lower end surface 50b of the cylindrical member 50 with a pair of holding claws 94a of the heat treatment jig 90. Let In this case, as in the fifth embodiment,
The gap t between the through hole 56 and the rod-shaped portion 92 is maintained at about 0.5 mm, and the rod-shaped portion 92 is not brought into contact with the through hole 56. The cylindrical member 50 to which the heat treatment jig 90 is fixed is fixed to the mounting table 33 of the container 30. The container 30 is filled with water 34.

In the above-described state, the induction heating coil 110 is brought close to the outer wall surface 54 of the cylindrical member 50, and a proper high frequency power is supplied to the induction heating coil 110 to bring the outer wall surface 54 into a predetermined shape. Induction heating to quenching temperature. The corner portion 59 is also heated by this induction heating. However, the gap t between the through hole 56 and the rod-shaped portion 92 is filled with water 34, and the corner portion 59 is cooled by the appropriate amount of the filled water 34. It is not heated above the temperature. Therefore, the corner portion 59 does not melt. Note that when the heat treatment jig 90 is not used, the through holes 56 are all filled with water 34, and the corner portions 59 are cooled too much. Therefore, the outer wall surface 5
Even if No. 4 reaches the predetermined quenching temperature, the corner portion 59 does not reach the predetermined quenching temperature. Therefore, the above-mentioned gap t is the corner portion 59.
Is set to a predetermined quenching temperature.

After induction heating the outer wall surface 54 and the corners 59 to a predetermined quenching temperature as described above, the induction heating coil 11
The high frequency power supplied to 0 is stopped. Since the outer wall surface 54 and the corner portion 59 are in contact with the water 34, they are rapidly cooled, and a hardened layer is formed on the outer wall surface 54 and the corner portion 59.

Although quenching is described in the above example, the heat treatment method described above can be applied to annealing and tempering. In this case, the outer wall surface 54 is heated to a predetermined annealing temperature or tempering temperature while cooling the corner portion 59 as described above. As a result, the outer wall surface 54 and the corner portion 59 are heated to a predetermined annealing temperature or tempering temperature.

Further, in each of the above-described embodiments, the bar portion is inserted into the through hole to form a gap between the through hole and the rod portion, and the cooling liquid is introduced into the gap to cool the corner portion. However, by contacting the pipe with the corner and the inner surface of the through hole,
The corners may be cooled by flowing a cooling liquid through this pipe. In this case, the temperature at which the corner is cooled can be appropriately adjusted by appropriately adjusting the temperature of the cooling liquid flowing through the pipe.

[0082]

As described above, according to the first heat treatment method of the present invention, the corner portion is induction-heated so as to have the same predetermined temperature as the peripheral portion to be induction-heated. Therefore, this corner is not heated to a predetermined temperature or higher.

Here, when the corner portion is induction-heated to reach the predetermined temperature, if the peripheral portion is induction-heated while cooling the corner portion, it is easy to bring the corner portion to the predetermined temperature. Can be induction heated.

Further, a jig having an outer diameter smaller than the inner diameter of the through hole is inserted into the through hole so as not to come into contact with the inner surface of the through hole, and is placed in the vicinity of the corner portion. When the peripheral portion is induction-heated while cooling, the cooling liquid is injected into the through hole to cool the corner portion. Since the corner portion is cooled, the temperature of the corner portion is appropriately cooled, and the temperature does not easily rise. Therefore, the corner portion is induction-heated so as to have the same predetermined temperature as the peripheral portion of the through hole. As a result,
The corners are not heated by induction heating above a predetermined temperature to melt.

Further, according to the second heat treatment method of the present invention, since water infiltrates into the gap between the jig and the through hole, the temperature of the corner portion is appropriately cooled and the temperature does not easily rise. Therefore, the corner portion is induction-heated so as to have the same predetermined temperature as the peripheral portion of the through hole. As a result, the corners are not heated by induction heating above a predetermined temperature to melt.

Further, according to the third heat treatment method of the present invention, the corner portion is induction-heated so as to have the same quenching temperature as the peripheral portion of the through hole. Therefore, this corner will not be heated by induction above a predetermined quenching temperature.

When induction heating the corners to the predetermined quenching temperature and induction heating the peripheral portions while cooling the corners, the corners are quenched Induction heating can be easily performed to reach the temperature.

Further, a jig having an outer diameter smaller than the inner diameter of the through hole is inserted into the through hole so as not to come into contact with the inner surface of the through hole, and is placed in the vicinity of the corner portion. When cooling the corners by injecting cooling liquid into the through-holes while inductively heating the peripheral part while cooling, the cooling liquid that has penetrated into the gap between the through-holes and the jig cools the corners. Therefore, the temperature of the corner portion is appropriately cooled, and the temperature hardly rises. Therefore, the corner portion is induction-heated so as to have the same predetermined temperature as the peripheral portion of the through hole. As a result, the corners are not heated by induction heating above a predetermined temperature to melt.

Further, according to the fourth heat treatment method of the present invention, since water infiltrates into the gap between the jig and the through hole, the temperature of the corner portion is appropriately cooled and the temperature does not easily rise. Therefore, the corner portion is induction-heated so as to have the same predetermined temperature as the peripheral portion of the through hole. As a result, the corners are not heated by induction heating above a predetermined temperature to melt.

Further, according to the fifth heat treatment method of the present invention, the two corner portions are induction-heated so as to have the same predetermined temperature as both the inner wall surface and the outer wall surface. Therefore, this corner is not heated to a predetermined temperature or higher.

Further, according to the sixth heat treatment method of the present invention, the corner portion is induction-heated to the same predetermined temperature as the inner wall surface. Therefore, this corner is not heated to a predetermined temperature or higher.

According to the seventh heat treatment method of the present invention, the corner portion is induction-heated so as to have the same predetermined temperature as the outer wall surface. Therefore, this corner is not heated to a predetermined temperature or higher.

Here, when the corner portion is induction-heated to reach the predetermined temperature, if the peripheral portion is induction-heated while cooling the corner portion, it is easy to bring the corner portion to the predetermined temperature. Can be induction heated.

Further, a jig having an outer diameter smaller than the inner diameter of the through hole is inserted into the through hole so as not to come into contact with the inner surface of the through hole, and is placed in the vicinity of the corner portion. When cooling the corners by injecting cooling liquid into the through-holes while inductively heating the peripheral part while cooling, the cooling liquid that has penetrated into the gap between the through-holes and the jig cools the corners. Therefore, the corner can be easily cooled.

Further, according to the eighth heat treatment method of the present invention, since water infiltrates into the gap between the jig and the through hole, the temperature of the corner portion is appropriately cooled and the temperature is unlikely to rise. Therefore, the corners are induction-heated so as to have the same predetermined temperature as the inner wall surface and the outer wall surface. As a result, the corners are not heated by induction heating above a predetermined temperature to melt.

Further, according to the ninth heat treatment method of the present invention, water infiltrates into the gap between the jig and the through hole, so that the temperature of the corner portion is appropriately cooled and the temperature does not easily rise. Therefore, the corner portion is induction-heated so as to have the same predetermined temperature as the inner wall surface. As a result, the corners are not heated by induction heating above a predetermined temperature to melt.

Further, according to the tenth heat treatment method of the present invention, since water infiltrates into the gap between the jig and the through hole, the temperature of the corner portion is appropriately cooled and the temperature is unlikely to rise. Therefore, the corner portion is induction-heated so as to have the same predetermined temperature as the outer wall surface. As a result, the corners are not heated by induction heating above a predetermined temperature to melt.

Further, according to the eleventh heat treatment method of the present invention, the corner portion is induction-heated so as to have the same quenching temperature as the peripheral portion of the through hole. Therefore, this corner will not be heated by induction above a predetermined quenching temperature.

Here, when the corners are induction-heated so as to reach the predetermined quenching temperature, if the peripheral portions are induction-heated while cooling the corners, the corners have a predetermined quenching temperature. Induction heating can be easily performed to reach the temperature.

Further, a jig having an outer diameter smaller than the inner diameter of the through hole is inserted into the through hole so as not to come into contact with the inner surface of the through hole, and is placed in the vicinity of the corner portion. When cooling the corners by cooling liquid by injecting the cooling liquid into the through holes when cooling the corners, the cooling liquid that has penetrated into the gap between the through holes and the jig cools the corners. Can be cooled.

Further, according to the twelfth heat treatment method of the present invention, since water penetrates into the gap between the jig and the through hole, the temperature of the corner portion is appropriately cooled and the temperature is unlikely to rise. Therefore, the corner portions are induction-heated so that the inner wall surface and the outer wall surface have the quenching temperature. As a result, the corners are not heated by induction heating above the quenching temperature and are not melted.

Further, according to the thirteenth heat treatment method of the present invention, since water infiltrates into the gap between the jig and the through hole, the temperature of the corner portion is appropriately cooled and the temperature does not easily rise. Therefore, the corners are induction-heated so that the quenching temperature is the same as that of the inner wall surface. As a result, the corners are not heated by induction heating above the quenching temperature and are not melted.

Further, according to the fourteenth heat treatment method of the present invention, since water infiltrates into the gap between the jig and the through hole, the temperature of the corner portion is appropriately cooled and the temperature is unlikely to rise. Therefore, the corners are induction-heated so that the quenching temperature is the same as that of the outer wall surface. As a result, the corners are not heated by induction heating above the quenching temperature and are not melted.

When the first heat treatment jig of the present invention is used to heat-treat a member having a through hole, the rod portion of the heat treatment jig should not come into contact with the inner surface of the through hole. Insert into the through hole. Therefore, a gap (space) is formed between the rod-shaped portion and the inner surface of the through hole. When induction heating is performed so that at least the peripheral portion of the through hole of both the one surface and the other surface of the member or one of the surfaces thereof is heated to a predetermined temperature, the cooling liquid is injected into the through hole. By changing the outer diameter of the rod-shaped portion, the amount of cooling liquid passing through the gap can be adjusted. Since this cooling liquid passes through the gap between the rod-shaped portion and the inner surface of the through hole, the corner portion formed by the peripheral portion and the through hole is cooled. As a result, the corners are induction-heated so as to have the same temperature as the peripheral portion of the through holes. Therefore, this corner is not heated to an unnecessarily high temperature.

When the second heat treatment jig of the present invention is used to heat-treat a cylindrical member having a through hole, the rod-shaped portion of the heat treatment jig does not contact the inner surface of the through hole. Is held by the holding part. Therefore, a gap (space) remains formed between the rod-shaped portion and the inner surface of the through hole. When induction heating is performed so that at least the peripheral portion of the through hole of both the inner wall surface and the outer wall surface of the cylindrical member or one of the surfaces thereof is heated to a predetermined temperature, the cooling liquid is sprayed into the through hole. By changing the outer diameter of the rod-shaped portion, the amount of cooling liquid passing through the gap can be adjusted. Since this cooling liquid passes through the gap between the rod-shaped portion and the inner surface of the through hole, the corner portion formed by the peripheral portion and the through hole is cooled. As a result, the corners are induction-heated so as to have the same temperature as the peripheral portion of the through holes. Therefore, this corner is not heated to an unnecessarily high temperature.

[Brief description of drawings]

FIG. 1 is a perspective view showing a flat plate and a heat treatment jig that are induction hardened in the atmosphere.

FIG. 2 is a cross-sectional view showing a flat plate in which a rod-shaped portion of the heat treatment jig of FIG. 1 is inserted into a through hole.

FIG. 3 is a cross-sectional view showing a flat plate and a heat treatment jig that are induction hardened in water.

FIG. 4 is a perspective view showing a cylindrical member and a heat treatment jig that are induction hardened in the atmosphere.

5 is a cross-sectional view showing a cylindrical member in which a rod-shaped portion of the heat treatment jig of FIG. 4 is inserted into a through hole.

FIG. 6 is a cross-sectional view showing a cylindrical member and a heat treatment jig that are induction hardened in water.

FIG. 7 is a perspective view showing a cylindrical member and a heat treatment jig that are induction hardened in the atmosphere.

8 is a cross-sectional view showing a cylindrical member having a rod-shaped portion of the heat treatment jig of FIG. 7 inserted into a through hole.

FIG. 9 is a cross-sectional view showing a cylindrical member and a heat treatment jig that are induction hardened in water.

[Explanation of symbols]

10 flat plate 11,58,59 Corner 12 One side of flat plate 14 Other side of flat plate 16,56 through holes 20, 60, 90 Heat treatment jig 22, 62, 92 bar 24, 64, 94 holding part 50 Cylindrical member 52 Inner wall surface 54 outer wall

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshihiro Aiba             84 Takata, Nishi-Sakai Town, Kariya City, Aichi Prefecture             Nami Onsen Co., Ltd. (72) Inventor Jun Fujie             84 Takata, Nishi-Sakai Town, Kariya City, Aichi Prefecture             Nami Onsen Co., Ltd. F-term (reference) 4K034 AA03 BA10 DB02 FA05 GA07

Claims (24)

[Claims] 1. A heat treatment method for heat treating a member having a through hole penetrating from one surface to the other surface, comprising at least one of the one surface and the other surface, or at least one of the surfaces. The peripheral portion of the through-hole is induction-heated to a predetermined temperature, and the corner portion formed by the peripheral portion to be induction-heated and the through-hole is also induction-heated to the predetermined temperature. Heat treatment method. 2. The heat treatment method according to claim 1, wherein when the corner portion is induction-heated to reach the predetermined temperature, the peripheral portion is induction-heated while cooling the corner portion. 3. A jig having an outer diameter smaller than the inner diameter of the through hole is inserted into the through hole so as not to contact the inner surface of the through hole and arranged in the vicinity of the corner portion. The heat treatment method according to claim 2, wherein when the peripheral portion is induction-heated while being cooled, the corner portion is cooled by injecting a cooling liquid into the through hole. 4. A heat treatment method of heat-treating a member in which a through-hole formed from one surface to the other surface is formed in water, wherein one or both of the one surface and the other surface When at least the peripheral portion of the through hole is induction-heated to a predetermined temperature, a jig having an outer diameter smaller than the inner diameter of the through hole is inserted into the through hole so as not to contact the inner surface of the through hole, A heat treatment method, wherein the jig is arranged in the vicinity of a corner formed by the through hole and the peripheral portion to be induction-heated. 5. A heat treatment method for induction hardening a member having a through hole penetrating from one surface to the other surface, the method comprising the steps of: At least the peripheral portion of the through hole is induction-heated so as to have a predetermined quenching temperature, and the corners formed by the peripheral portion to be induction-heated and the through hole also have the predetermined quenching temperature. A heat treatment method characterized by induction hardening and quenching. 6. The induction heating of the peripheral portion while cooling the corner when induction heating the corner to reach the predetermined quenching temperature. Heat treatment method. 7. A jig having an outer diameter smaller than the inner diameter of the through hole is inserted into the through hole so as not to contact the inner surface of the through hole and arranged in the vicinity of the corner portion. 7. The heat treatment method according to claim 6, wherein a cooling liquid is injected into the through hole to cool the corner when the peripheral portion is induction-heated while being cooled. 8. In a heat treatment method of induction hardening in water a member having a through hole penetrating from one surface to the other surface, a jig having an outer diameter smaller than the inner diameter of the through hole is provided in the through hole. An angle formed by at least the peripheral portion of the through hole and the through hole of both the one surface and the other surface or one of the surfaces by inserting the through hole so as not to contact the inner surface. A heat treatment method, characterized in that the jig is arranged in the vicinity of a portion, and the peripheral portion is induction-heated and quenched to a predetermined quenching temperature. 9. A heat treatment method for heat-treating a cylindrical member having a through hole penetrating from an inner wall surface to an outer wall surface, wherein both the inner wall surface and the outer wall surface are induction-heated to a predetermined temperature, and A heat treatment method, characterized in that both the corners formed by the inner wall surface and the through hole and the corners formed by the outer wall surface and the through hole are induction-heated to the predetermined temperature. 10. A heat treatment method for heat-treating a cylindrical member having a through hole penetrating from an inner wall surface to an outer wall surface, wherein the inner wall surface is induction-heated to a predetermined temperature, and the inner wall surface and the through-hole are penetrated. A heat treatment method, characterized in that the corners formed by the holes are also induction heated so as to reach the predetermined temperature. 11. A heat treatment method for heat-treating a cylindrical member having a through hole penetrating from an inner wall surface to an outer wall surface, wherein the outer wall surface is induction-heated to a predetermined temperature, and the outer wall surface and the through-hole are penetrated. A heat treatment method, characterized in that the corners formed by the holes are also induction heated so as to reach the predetermined temperature. 12. The induction heating of the peripheral portion while cooling the corner portion when the corner portion is induction-heated to reach the predetermined temperature, according to claim 9, 10, or 11. The heat treatment method described. 13. A jig having an outer diameter smaller than the inner diameter of the through hole is inserted into the through hole so as not to contact the inner surface of the through hole and arranged in the vicinity of the corner portion. The heat treatment method according to claim 12, wherein when the peripheral portion is induction-heated while being cooled, a cooling liquid is injected into the through hole to cool the corner portion. 14. A heat treatment method for heat-treating, in water, a cylindrical member having a through hole penetrating from an inner wall surface to an outer wall surface, wherein a jig having an outer diameter smaller than the inner diameter of the through hole is used for the inner surface of the through hole. The jig so as not to come into contact with the through hole, and arrange the jig in the vicinity of both the corner formed by the inner wall surface and the through hole and the corner formed by the outer wall surface and the through hole. A heat treatment method, characterized in that the inner wall surface and the outer wall surface are induction-heated to a predetermined temperature. 15. A heat treatment method for heat-treating a cylindrical member having a through hole penetrating from an inner wall surface to an outer wall surface in water, wherein a jig having an outer diameter smaller than the inner diameter of the through hole is used for the inner surface of the through hole. The inner wall surface and the through hole so that the inner wall surface is induction-heated to a predetermined temperature by inserting the jig in the vicinity of a corner formed by the inner wall surface and the through hole. Characterizing heat treatment method. 16. A heat treatment method for heat-treating a cylindrical member having a through hole penetrating from an inner wall surface to an outer wall surface in water, wherein a jig having an outer diameter smaller than the inner diameter of the through hole is used for the inner surface of the through hole. The jig is placed in the vicinity of the corner formed by the outer wall surface and the through hole so that the outer wall surface is induction-heated to a predetermined temperature. Characterizing heat treatment method. 17. A heat treatment method for induction hardening a cylindrical member having a through hole penetrating from an inner wall surface to an outer wall surface, wherein at least the inner wall surface and the outer wall surface, or at least one of the wall surfaces. The peripheral portion of the through hole is induction-heated to a predetermined quenching temperature, and the corners formed by the peripheral portion to be induction-heated and the through hole are also induction-heated to the predetermined quenching temperature. A heat treatment method, which comprises: 18. The induction heating of the peripheral portion while cooling the corner portion when induction heating the corner portion to the predetermined quenching temperature. Heat treatment method. 19. A jig having an outer diameter smaller than the inner diameter of the through hole is inserted into the through hole so as not to come into contact with the inner surface of the through hole and arranged in the vicinity of the corner portion. 19. The heat treatment method according to claim 18, wherein when the peripheral portion is induction-heated while being cooled, the corner portion is cooled by injecting a cooling liquid into the through hole. 20. A heat treatment method of induction hardening in water a cylindrical member having a through hole penetrating from an inner wall surface to an outer wall surface, wherein a jig having an outer diameter smaller than the inner diameter of the through hole is used. The jig is inserted into the through hole so as not to contact the inner surface, and the jig is arranged in the vicinity of both the corner formed by the inner wall surface and the through hole and the corner formed by the outer wall surface and the through hole. A heat treatment method, characterized in that the inner wall surface and the outer wall surface are induction-heated to a predetermined quenching temperature for quenching. 21. In a heat treatment method of induction hardening in water a cylindrical member having a through hole penetrating from an inner wall surface to an outer wall surface, a jig having an outer diameter smaller than the inner diameter of the through hole is used. Insert it into the through hole so as not to contact the inner surface, place the jig near the corner formed by the inner wall surface and the through hole, and guide the inner wall surface to a predetermined quenching temperature. A heat treatment method comprising heating and quenching. 22. In a heat treatment method of induction hardening a cylindrical member having a through hole penetrating from an inner wall surface to an outer wall surface in water, a jig having an outer diameter smaller than the inner diameter of the through hole is provided in the through hole. Insert it into the through hole so as not to contact the inner surface, and arrange the jig in the vicinity of the corner formed by the outer wall surface and the through hole, and guide the outer wall surface to a predetermined quenching temperature. A heat treatment method characterized by heating. 23. A heat treatment jig used for heat-treating a member having a through hole penetrating from one surface to the other surface, wherein the jig has an outer diameter smaller than the inner diameter of the through hole. A heat treatment jig comprising a rod-shaped portion that is inserted into the through hole so as not to contact the inner surface of the through hole. 24. A heat treatment jig used for heat-treating a cylindrical member having a through hole penetrating from an inner wall surface to an outer wall surface, wherein a rod-shaped portion having an outer diameter smaller than an inner diameter of the through hole. And a holder for holding the rod-shaped portion in the through hole so that the rod-shaped portion does not come into contact with the inner surface of the through hole.