JPH0226932Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an induction hardening device for a rack shaft of a rack and pinion type steering device for automobiles, etc., and particularly to an induction hardening device that uses both high frequency induction and direct energization.

This type of induction hardening apparatus is known to have an induction electrode disposed close to the rack shaft and a pair of current-carrying electrodes disposed at both ends of the induction electrode and in contact with the rack shaft. ing.

In this way, a device in which a high-frequency induced current is induced in the rack shaft by an induction electrode, and at the same time, a high-frequency current is directly passed through a pair of contact electrodes,
Since it has good heating efficiency and is suitable for heating uneven surfaces, it is suitable for induction hardening of the rack shaft of a rack and pinion type steering device.

By the way, the pair of current-carrying electrodes are pressed into contact with the rack shaft at a distance, and the part between them becomes red-hot, so the electrodes themselves become hot and form an oxide film on their surface, causing them to become in contact with the rack shaft. Poor electrical contact is likely to occur between the two. If such electrical contact failure occurs, there will be problems such as sparks occurring between the current-carrying electrode and the rack shaft, and further heating of the contact surface. In addition, since the current-carrying electrode is pressed against the rack shaft under relatively strong pressure, wear and deformation of the electrode will be accelerated if the electrode itself becomes hot and softens. Since the distance between the rack and the induction coil is set, the distance changes, causing problems such as fluctuations in the heating conditions and the possibility that the rack shaft may come into contact with the induction coil and generate sparks.

The present invention has been developed in view of these points, and aims to prevent the formation of an oxide film on the surface of the current-carrying electrode, eliminate the disadvantages caused by the oxide film, and at the same time extend the life of the electrode.

The present invention will be explained below based on embodiments as shown in the drawings.

In FIG. 1, reference numeral 2 denotes an induction electrode, which is placed close to the rack shaft 1. In FIG. The induction electrode 2 is hollow inside and has a large number of small holes 14, and also serves as a quenching water spouting device. A pair of current-carrying electrodes 3, 4 are provided on both sides of the induction electrode 2, and the current-carrying electrodes 3, 4 are pressed against the surface of the rack shaft 1 by clamp devices 9, 10. The current-carrying electrodes 3 and 4 have a second
As shown in the figure, a blind hole is provided as the liquid chamber 6, and a plurality of small holes 8 are provided which communicate from this liquid chamber to the arcuate contact surface 5 with the rack shaft. Further, a refrigerant liquid supply pipe 7 is tightly fitted into the open end of the liquid chamber 6. This refrigerant liquid supply pipe 7 is connected to the discharge side of the pump 11 and injects a preferably conductive refrigerant liquid into the liquid chamber 6 . In the drawings, 12 is a high frequency power source, and 13 is a quenching water supply pump.

During hardening, the rack shaft 1 is connected to the current-carrying electrodes 3 and 4.
They are placed on top of each other and brought into pressure contact with each other using clamp devices 9 and 10, and then a high frequency current is supplied from a high frequency power source 12. A high-frequency current is induced in the rack shaft 1 by the induction electrode 2, and at the same time, the high-frequency current is directly passed through the current-carrying electrodes 3, 4. As a result, in this figure, the back side of the rack shaft is rapidly heated.
Simultaneously with the supply of this high-frequency current, appropriate refrigerant liquid is injected into the liquid chambers 6 of the current-carrying electrodes 3 and 4 from the pump 11 via the refrigerant liquid supply pipe 7. The injected refrigerant liquid is ejected from the small hole 8 onto the contact surface between the current-carrying electrode and the rack shaft, thereby preventing the contact surface from being heated. After the rack shaft 1 is heated for a predetermined period of time, quenching water is jetted out from the many small holes 14 of the induction electrode 2 to rapidly cool the rack shaft 1 and harden it.

The refrigerant liquid injected into the liquid chambers 6 of the current-carrying electrodes 3 and 4 and ejected from the small holes 8 may also be used as quenching water, or a dedicated refrigerant liquid may be prepared separately. Further, it is desirable that the small hole 8 is directed toward the side where the induction coil 2 is not located so that the refrigerant liquid spouted from the small hole 8 does not inadvertently come into contact with the heated portion of the rack shaft. Although the refrigerant liquid may be spouted only while the rack shaft is being heated, it is more effective if the quenching water is spouted until the rack shaft is completely cooled.

As mentioned above, the present invention involves induction hardening of a rack shaft having an induction electrode disposed close to the rack shaft and a pair of energized electrodes disposed at both ends of the induction electrode and in contact with the rack shaft. In the device, a liquid chamber is provided in the current-carrying electrode, and a small hole is provided that communicates from the liquid chamber to the contact surface with the rack shaft, and a refrigerant liquid supply pipe is tightly fitted into this liquid chamber, so that the refrigerant is discharged from the small hole. It can prevent the contact surface of the current-carrying electrode with the easy shaft from heating up due to the jetting of liquid, which can prevent the formation of an undesirable oxide film and the electrode from being softened at high temperatures, thereby extending the life of the electrode. can.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view of an embodiment of the present invention, and FIG. 2 is a sectional view taken along line A--A in FIG. Explanation of symbols, 1... Rack shaft, 2... Induction electrode, 3, 4... Current carrying electrode, 5... Contact surface of current carrying electrode, 6... Liquid chamber, 7... Refrigerant liquid supply pipe, 8...
...Small hole.

Claims (1)

[Scope of utility model registration request] Induction electrode 2 placed close to rack axis 1
In a rack shaft induction hardening apparatus having a pair of current-carrying electrodes 3 and 4 disposed at both ends of the induction electrode and in contact with the rack shaft 1, a liquid chamber 6 is provided in the current-carrying electrodes 3 and 4. and a small hole 8 communicating from the liquid chamber 6 to the contact surface 5 with the rack shaft,
This easy-shaft induction hardening apparatus is characterized in that a refrigerant liquid supply pipe 7 is tightly fitted into the liquid chamber 6.