JP2003221622A - Method for induction-hardening internal tooth, and induction hardening device used for it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a workpiece from deforming by heat for induction- hardening internal tooth, and to assure required accuracy. <P>SOLUTION: The method for induction-hardening the internal tooth 18 formed in the inner circumference of a flange 16 of the workpiece 10, in which a base 12 is connected with the above flange 16 located at a perimeter of the base 12 with a step, because of being half-blanking-formed, comprises heating the above flange 16 from its periphery side till the internal tooth 18 reaches a predetermined temperature, and then cooling the above flange 16 from the periphery side. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction hardening method for an inner tooth on an inner circumference of a flange portion of a half-blanked work and an induction hardening apparatus used for the method.

[0002]

2. Description of the Related Art Conventionally, as a technique relating to this type of induction hardening, for example, a method for hardening a lock tooth portion disclosed in Japanese Patent Laid-Open No. 11-20517 is known. This technology targets a tooth plate in a reclining device for a vehicle. This tooth plate is a half-blank formed product by press working, and a flange portion is positioned with a step on the outer periphery of the base portion, and tooth portions (inner teeth) are formed on the inner periphery of the flange portion. After induction heating with high frequency is applied to the teeth from the inside of the flange (base side), the teeth and their surroundings are induction hardened and the surface layer is quenched. Making layers.

[0003]

Since the tooth plate is a half-blank molded product, when the tooth portion is heated from the inside of the flange portion, the connecting portion between the base portion and the flange portion is also heated. The press stress of the half blanking is released. As a result, the flange portion is deformed so as to open outward, and it becomes difficult to ensure accuracy after quenching.
The present invention is intended to solve the above problems, and an object thereof is to prevent deformation of a work due to heating for induction hardening of internal teeth and to secure required accuracy.

[0004]

SUMMARY OF THE INVENTION The present invention is to achieve the above object. According to the invention of claim 1, there is a step between the base and the flange located on the outer periphery of the base by half blanking. A method for induction hardening of internal teeth formed on the inner circumference of the flange part, targeting the workpieces connected to each other, wherein the flange part is heated from its outer peripheral side until the inner teeth reach a predetermined temperature. After that, the flange portion is similarly cooled from the outer peripheral side thereof. By performing induction heating with high frequency from the outer peripheral side of the flange portion in this manner, it becomes possible to heat only the flange portion having the internal teeth without directly applying the high frequency magnetic flux to the base portion. As a result, it is possible to prevent the connection portion between the base portion and the flange portion of the work from being heated and deformed.

A second aspect of the present invention is the induction hardening method for internal teeth according to the first aspect, wherein a high frequency current is passed through a heating coil disposed on the outer peripheral side of the flange portion. After heating the flange portion, the cooling liquid in the cooling liquid passage formed inside the heating coil is sprayed to the outer peripheral side of the flange portion to rapidly cool the flange portion. The induction heating that accompanies the high-frequency current makes it possible to heat the flange portion of the workpiece for a short time, and the heating is completed before the joint portion between the base portion and the flange portion of the workpiece is heated. Only can be heated. As a result, it is possible to prevent the connecting portion of the work from being deformed, and the required accuracy is ensured even after quenching.

A third aspect of the present invention is the induction hardening method for internal teeth according to the second aspect, wherein the workpiece is heated by the heating coil and the cooling liquid passage when the flange portion is heated and cooled. It is characterized by rotating along. As a result, the flange portion is evenly heated and cooled in the circumferential direction.

According to a fourth aspect of the present invention, there is provided an induction hardening apparatus for use in the induction hardening method for internal teeth according to the first aspect, which is arranged so as to surround the outer periphery of the flange portion, Heating means capable of high-frequency heating from the outer peripheral side, and provided integrally with this heating means,
And a cooling means capable of cooling the flange portion from the outer peripheral side. This makes it possible to easily set equipment for induction hardening on the inner teeth of the flange portion.

The invention according to claim 5 is the induction hardening apparatus according to claim 4, wherein the heating means is a heating coil capable of heating the flange portion by passing a high frequency current. is there. The cooling means is a cooling liquid passage that is formed inside the heating coil and that can spray the cooling liquid supplied thereto to the flange portion to rapidly cool the flange portion. This makes it easy to switch the cooling with the cooling liquid after heating the flange portion, and also makes the timing setting easy. Further, the equipment for induction hardening the inner teeth of the flange portion is also simplified.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. In the present embodiment, an induction hardening technique for a housing of a round type internal tooth reclining device for an automobile will be described. 1 is an external perspective view of the induction hardening apparatus, FIG. 2 is a plan view of the same induction hardening apparatus, and FIG. 3 is an enlarged sectional view taken along the line AA of FIG. A work 10 shown in these drawings is a housing of the reclining device. The work 10 is a half-pressed product formed by pressing, and the flange portion 1 is formed on the outer periphery of the base portion 12.
6 is located with a step.

That is, the work 10 is an intermediate product having a structure in which the flange portion 16 is connected to the base portion 12 in a stepped shape by half-pressing the metal material with a press die. A center hole 14 is punched and formed in the center of the base portion 12, and a plurality of protrusions 15 are formed on the surface of the base portion 12 on the same circumference centered on the center hole 14.
Are pressed at regular intervals in the circumferential direction (Fig. 3).
These convex portions 15 are for positioning and mounting the work 10 which is the housing of the reclining device on a seat frame (not shown). Also the flange 1
Inner teeth 18 are formed on the inner circumference of 6. In order to secure the hardness required for the internal teeth 18, the induction hardening device
This is an apparatus for applying induction hardening to the internal teeth 18.

The induction hardening apparatus is provided with a jacket 20 having a shape surrounding the outer peripheral portion of the work 10. A high frequency current can be applied to the jacket 20 through a lead wire 22. The jacket 20 functions as a heating coil when a high-frequency current is applied.

The jacket 20 is hollow and has a cooling liquid passage 24 inside (FIG. 3). A cooling liquid such as water can be supplied to the inlet 26 of the jacket 20 from a predetermined supply source (not shown), and the supplied cooling liquid is sent from the inlet 26 to the cooling liquid passage 24. The cooling liquid that has entered the cooling liquid passage 24 is ejected inward from a large number of ejection holes 28 (FIG. 3) formed in the inner peripheral wall of the jacket 20.

To subject the inner teeth 18 to induction hardening, the work 10 is set inside the jacket 20 as shown in the drawing. In this state, high-frequency current (7.5
(About 40 KHz), and the work 10 is rotated around the axis of the central hole 14. As a result, the jacket 20
By the (heating coil), the flange portion 16 of the work 10 is induction-heated from the outer peripheral surface 16a side. This heating is performed when the temperature of the internal teeth 18 is at the tips 18a (Fig. 4) of the internal teeth 18.
Heating is aimed at reaching 1000-1100 ° C.

Although it is possible to directly measure and manage the temperature of the tooth tip 18a of the inner tooth 18, the temperature of the portion of the flange 16 farther from the outer peripheral surface 16a by a predetermined distance L (FIG. 4). Is easier to measure.
Specifically, the temperature of the internal teeth 18 can be set to the above-mentioned target value by controlling the temperature of the portion where the distance L is about 2.5 mm to be about 1200 ° C.

Further, it is also possible to manage by power control without measuring temperature. For example, the tooth tips 18a of the inner teeth 18 can be heated to a target temperature of 1000 to 1100 ° C. by passing a high frequency current at a voltage of 390 V and a conduction time of 2.58 seconds. Then, the target temperature of the tooth tip 18a can be easily adjusted by appropriately changing the voltage and the energization time.

In this way, the flange portion 16 is attached to the outer peripheral surface 1 thereof.
By heating for a short time by induction heating from the side of 6a, the high frequency magnetic flux does not directly hit the base portion 12, and the connecting portion 17 between the base portion 12 and the flange portion 16 (FIG. 4).
Heating can be completed before heat is transferred to As a result, only the flange portion 16 can be heated, and the connecting portion 17
Deformation due to heating is eliminated.

Compressive stress during press molding remains in the base portion 12 around the back side of each convex portion 15.
If 0 is heated from the inside of the flange portion 16, the compressive stress around the back side of each convex portion 15 is released due to the heat effect, and the base portion 12 is deformed. But the flange part 1
By heating 6 from the outer peripheral surface 16a side, it is possible to prevent the periphery of the back side of each convex portion 15 from being heated. This also causes the deformation of the base portion 12, and thus the work 10.
Is prevented from being deformed.

When the temperature of the inner teeth 18 reaches the target value, the high frequency current is stopped and the coolant passage 2 of the jacket 20 is stopped.
4, the cooling liquid is supplied to each of the ejection holes 28 and the flange portion 16
The cooling liquid is sprayed onto the outer peripheral surface 16a of the. As a result, the flange portion 16 is rapidly cooled, the inner teeth 18 are induction hardened to a predetermined hardness, and the above-mentioned thermal deformation is prevented, so that the required accuracy of the work 10 is secured even after the hardening. When the flange portion 16 is heated and cooled, the workpiece 10 is rotated around the axis of the central hole 14, so that the flange portion 16 is uniformly heated and cooled in the circumferential direction. . In this way, the jacket 20 (heating coil) when the high-frequency current is passed is the heating means of the induction hardening apparatus, and the cooling liquid passage 24 of the jacket 20 is the cooling means of the induction hardening apparatus.

FIG. 5 is an explanatory view showing an example of heating and cooling characteristics for the flange portion 16 of the work 10. The temperature T on the vertical axis in this drawing is the tip 18a of the internal tooth 18.
Is a value that reaches 1000 to 1100 ° C. Further, since the flange portion 16 is heated and cooled by using the jacket 20 arranged on the outer periphery of the work 10, the switching between heating and cooling is performed with good timing, as is apparent from FIG. For the same reason, the internal teeth 1 of the work 10
8 is also easy to set for induction hardening, leading to improved productivity.

[Brief description of drawings]

FIG. 1 is an external perspective view of an induction hardening apparatus.

FIG. 2 is a plan view of an induction hardening apparatus.

FIG. 3 is an enlarged sectional view taken along line AA of FIG.

FIG. 4 is an enlarged cross-sectional view showing the outer peripheral portion of the work.

FIG. 5 is an explanatory diagram showing an example of heating and cooling characteristics for a work.

[Explanation of symbols]

10 work 12 Base 16 Flange 18 internal teeth 20 jacket (heating coil) 24 Coolant passage

Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05B 6/10 331 H05B 6/10 331 (72) Inventor Yoshimasa Tanaka 5893 Tamura, Hiratsuka-shi, Kanagawa High Frequency Heat Smelting Co., Ltd. (72) Inventor Katsumi Omiya 5893 Tamura, Hiratsuka-shi, Kanagawa High-frequency smelting Co., Ltd. Internal F-term (reference) 3J030 AC03 BA01 BA10 BC03 BC10 3K059 AA09 AA10 AB22 AD03 AD04 AD05 AD34 AD37 CD48 CD74 4K042 AA18 BA10 DA01 DB01 DD04 DE02 DF02 EA01

Claims (5)

[Claims] 1. An induction hardening method for an internal tooth formed on the inner circumference of a flange part for a work in which a base part and a flange part located on the outer circumference thereof are connected with a step by half blanking. A method for induction hardening an internal tooth, comprising heating the flange portion from the outer peripheral side thereof until the internal teeth reach a predetermined temperature, and then cooling the flange portion from the outer peripheral side thereof. 2. The induction hardening method for internal teeth according to claim 1, wherein after heating the flange portion by passing a high-frequency current through a heating coil arranged on the outer peripheral side of the flange portion, An induction hardening method for internal teeth, characterized in that a cooling liquid in a cooling liquid passage formed inside the heating coil is sprayed onto the outer peripheral side of the flange portion to rapidly cool the flange portion. 3. The induction hardening method for internal teeth according to claim 2, wherein the work is rotated along the heating coil and the cooling liquid passage during heating and cooling of the flange portion. A characteristic induction hardening method for internal teeth. 4. The induction hardening apparatus used in the induction hardening method for internal teeth according to claim 1, wherein the induction hardening apparatus is arranged so as to surround the outer periphery of the flange portion, and the flange portion is induction heated from the outer peripheral side. An induction hardening apparatus comprising: a heating means capable of performing the above-described heating; and a cooling means that is integrally provided with the heating means and that can cool the flange portion from the outer peripheral side. 5. The induction hardening apparatus according to claim 4, wherein the heating means is a heating coil capable of heating the flange portion by passing a high frequency current, and the cooling means. An induction hardening apparatus which is a cooling liquid passage which is formed inside the heating coil and which is capable of spraying a cooling liquid supplied thereto to the flange portion to rapidly cool the flange portion.