JPS5827330B2 - Induction hardening method for the periphery of a cylindrical body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for induction hardening the circumferential surface of a cylindrical body, and more particularly to a continuous induction hardening method for the circumferential surface of a cylindrical body.

For induction hardening, there is a one-shot hardening method in which the parts of the object to be heated that need to be hardened are heated at once and then cooled down, and a method in which the heating coil and the object to be heated are moved relative to each other. The parts that require quenching are heated one after another, and cooling water is then injected.
There is a continuous quenching method in which the heated part is sequentially cooled.

Among these methods, the continuous quenching method is suitable for quenching long objects, but when cooling the heating part, the heating part is only instantaneously cooled by the jetted cooling water, and the amount of sprayed water is reduced. Since it is difficult to control uniformity, it is difficult to obtain a homogeneous hardened layer.

The present invention provides a continuous high-frequency quenching method that solves these problems, and its feature is that the cooling water injected into the heated part of the circumferential surface of the cylindrical body is retained in the lower part of the cylindrical body. The purpose is to maintain the water surface at a constant distance below the heating coil.

The present invention will be described below with reference to embodiments shown in the drawings.

The examples show the implementation of the induction hardening method according to the present invention on a bottomed cylindrical body.

In the figure, reference numeral 1 indicates an induction hardening device, which is composed of a heating section 2, a cooling section 3, and a cooling water discharge section 4.

The heating section 2 includes a heating coil 6 disposed along the inner circumferential surface 5a of a cylindrical body 5 as a heated body at an appropriate distance from the inner circumferential surface, and a heating coil 6 connected to the upper surface thereof. , 8.

The cooling unit 3 includes a jacket 11 equipped with a large number of cooling water injection holes 10 on the lower periphery, a cooling water supply pipe 12 connected to the upper surface of the jacket, and a cooling water supply pipe 12 that supplies cooling water to the jacket 11 through the supply pipe. It consists of a discharge pump 13 for pressure feeding.

The cooling water discharge section 4 includes a discharge pipe 14 in which a cooling water suction opening end 14a is located below the heating coil 6, and a suction pump 15 that discharges the cooling water to the outside of the cylindrical body 5 through the protection pipe. It consists of

In the induction hardening apparatus of the embodiment, the heating coil 6 is fixedly supported on the circumferential surface of the jacket 11, and the discharge pipe 14 is inserted and supported through the jacket 11, so that the suction opening end 14a of the discharge pipe 14 is fixedly supported.
The gap α between the heating coil 6 and the heating coil 6 is maintained constant, and the jacket 11 is fixedly installed on the frame (not shown) of the apparatus.

In this embodiment, in order to relatively move the Calo heating coil 6 and the cylindrical body 5, which is the heated body, the cylindrical body 5 can be moved up and down by appropriate means.

The quenching method according to the present invention uses such a quenching apparatus 1, and first, the cylindrical body 5 is heated so that the heating coil 6 of the apparatus is located at the bottom of the cylindrical body 5. is raised, and then a high frequency current is passed through the heating coil 6 to heat the inner circumferential surface 5a of the cylindrical body 5.

Subsequently, the cylindrical body 5 is continuously lowered, and cooling water is injected from the injection hole 10 of the jacket 11 to continuously cool and harden the heated portion of the inner circumferential surface 5a of the cylindrical body 5. Layer 5b is obtained.

The injected cooling water 16 immediately stays at the bottom of the cylindrical body 5, and continues to cool the injected cooled Gallo heat section.

At this time, excess cooling water 16 is discharged from the suction pump 15 to the outside of the cylindrical body 5 via the discharge pipe 14.

In addition, in the above embodiment, hardening of a cylindrical body with a bottom was explained as the cylindrical body 5, but the hardening method of the present invention is not limited to a cylindrical body with a bottom. In that case, the discharge pipe 14 is inserted into the cylindrical body from below, and the distance α between the suction opening end 14a of the discharge pipe 14 and the heating coil 6 is always kept constant. The suction pump 15 may be installed in such a manner that the suction pump 15 is not required.

In the continuous induction hardening method according to the present invention, the cooling water used in injection cooling is retained at the bottom of the cylindrical body, the hardened layer is immersed in the retained cooling water to be cooled again, and the hardened layer is started to be immersed. Since the speed is made to correspond to the moving feed rate of the heating coil, an extremely homogeneous hardened layer can be obtained.

[Brief explanation of the drawing]

The drawings are conceptual cross-sectional views of a quenching device and a cylindrical body for explaining a method for induction hardening the inner peripheral surface of a cylindrical body according to the present invention. 1... Quenching device, 2... Heating section, 3.
...Cooling section, 4...Cooling water discharge section, 5.
... Cylindrical body, 6 ... Heating coil, 9 ...
...High frequency power supply, 10...Injection hole, 11.
... Jacket, 12 ... Cooling water supply pipe, 13 ... Discharge pump, 14 ... Cooling water discharge pipe, 15 ... Suction Pump, 16...
··Cooling water.

Claims (1)

[Claims] 1 Heat the circumferential surface of the cylindrical body without moving the heating coil and the cylindrical body relative to each other, and inject cooling water to the heated part while following the heated part to the circumferential surface of the cylindrical body. In the continuous induction hardening method for quenching, the cooling water is retained in the lower part of the cylindrical body, and the water surface is maintained at a constant distance below the heating coil. Induction hardening method.