JPS6344801B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to induction hardening technology, and particularly to an induction hardening apparatus for parts having roller grooves on the inner surface, such as the outer ring member of a sliding tripod joint in which a cover part and a race surface are integrally formed. Regarding.

Conventionally, in induction hardening of sliding type tripod joint outer ring members, etc. in which the cover part and the race surface are integrally formed, in order to prevent cracking at the opening end of the petal outer part (hereinafter simply referred to as the outer part) of the inner petal shape, There is an induction hardening device that applies a cold metal to the open end to form an unhardened portion at the open end of the outer shell.

However, in such an induction hardening apparatus, since a secondary current flows through the chilled metal, a discharge occurs between the chilled metal and the open end of the component, resulting in the formation of spark marks on the open end of the component.

In addition, since the chiller is made of soft materials such as copper or silver, which have good electrical and thermal conductivity,
There is a drawback that the flatness of the chilled metal deteriorates due to wear, dents, etc.

If the chiller is severely damaged, quenching cracks may occur at the opening end of the outer shell.

The present invention disposes a secondary coil close to the open end of the outer shell of the component, so that the electromagnetic induction effect of the secondary coil cancels out the electromagnetic induction effect caused by high-frequency current flowing through the hardened coil. Therefore, it is an object of the present invention to provide an induction hardening device that forms a non-hardened portion at the open end of the outer shell of a component, thereby preventing the problem of spark marks on the component and preventing the occurrence of quench cracking at the open end of the outer shell. do.

This purpose is an induction hardening device that hardens the inner periphery of a component that has roller grooves on its inner surface. It forms a petal shape that follows the inner circumference of the part (hereinafter simply referred to as the part), and a ferrite core is placed in the center of each petal, and on the outside of the part,
One end of the jig for holding the component receives the flange portion of the component to hold the component, and the other end has a slight gap with the end surface of the component and has an inner shape that allows the quenching coil to pass through, A secondary coil is fixed so as to protrude inward from the inner shape of the part facing the petal outer part of the quenched coil, and further, a cooling jacket fixed to the quenched coil is disposed directly below the quenched coil. This is achieved by an induction hardening device featuring the following.

Embodiments of the present invention will be described below based on the accompanying drawings.

FIGS. 1 and 2 show an induction hardening apparatus according to the present invention.

For induction hardening, first, place part 1 in jig 7.
Position and install.

Next, a saddle (not shown) to which the jig 7 is fixed is raised and stopped at a position where the hardened coil 5 fixed to the lead 10 penetrates the part and is partially inserted into the secondary coil 8.

At this position, set the quenching coil 5 to 10~60KHz, 1000~
When a high frequency current of 6000A is applied, the ferrite core 6
Due to the reactance increasing effect of
flows along the outer shape of the hardened coil 5.

A secondary current i' is induced and flows in the inner circumference of the secondary coil 8 by this high-frequency current i.

Therefore, the secondary coil 8 close to the hardened coil 5
In the notch 11, the magnetic field ψ formed by the high frequency current i of the hardened coil 5 is converted into the secondary current of the secondary coil 8.
The magnetic field ψ′ formed by i′ acts in directions that cancel each other out, making it difficult for the opening end of the outer shell to be heated.

On the other hand, in other parts, the distance between the quenching coil 5 and the secondary coil 8 is large, so that the inner surface of the part is heated. In this state, stop heating is performed while the high frequency current i is flowing through the hardening coil 5 for 0.5 to 1 second.

Next, while keeping the high frequency current i flowing through the hardening coil 5, the saddle (not shown) is moved 5 to 10 mm/
When the distance between the quenched coil 5 and the secondary coil 8 increases by lowering at a speed of sec, the secondary current of the secondary coil 8 increases.
i' stops flowing, and the inner periphery of the component 1 begins to heat up.

Thereafter, as in normal moving hardening, the part 1 is lowered and cooled by high-frequency heating and cooling water injected from the injection hole 12 of the cooling jacket 9 to form a hardened part 2 on the inner periphery of the part 1. It is something to do.

As is clear from the above, according to the induction hardening apparatus according to the present invention, a non-hardened portion can be formed at the open end of the outer shell due to the action of the secondary coil that does not contact the component. It does not leave spark marks and is highly reliable in preventing cracking.

Since the hardened portion of the roller groove can be formed up to the opening end surface, the amount of "slide out" that is the effective range of joint use can be increased.

Since the secondary current of the high-frequency current of the hardened coil flows through the inner peripheral surface of the component forming a closed circuit, the hardened coil is highly efficient.

Since the component holding jig can be made of hard metal such as stainless steel, the jig has excellent durability.

There are advantages such as

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the part held in a jig and a moving quenching start position with a quenching coil inserted, and FIG. 2 is a bottom view of FIG. 1 with the cooling jacket removed. DESCRIPTION OF SYMBOLS 1... Part to be hardened, 2... Hardened part, 3... Outer shell opening end, 4... Roller groove, 5... Hardened coil, 6... Ferrite core, 7... Jig, 8... Secondary coil, 9... Cooling jacket , 10... Lead, 11... Secondary coil notch, 12... Cooling water injection hole, ψ... Magnetic field of hardened coil, ψ'... Magnetic field of secondary coil.

Claims (1)

[Claims] 1. An induction hardening device for surface hardening the inner periphery of a component having roller grooves on the inner surface, the quenching coil being connected to a high frequency transformer via a lead to harden the inner periphery of the component. , it forms a petal shape that follows the inner circumference of the part to be processed (hereinafter simply referred to as the part), and a ferrite core is placed in the center of each petal, and a ferrite core is placed on the outside of the part to hold the part. One end of the jig holds the component by receiving the flange of the component, and the other end has a slight gap with the end surface of the component and has an inner shape that allows the quenching coil to pass through. A secondary coil is fixed so as to protrude inward from the inner shape of the part facing the petal outer part of the coil, and further, a cooling jacket fixed to the hardened coil is disposed directly below the hardened coil. induction hardening equipment.