JPH0332515Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is a high-frequency energized induction coil used for hardening the rack teeth and tooth bottoms of steering rack shafts used in 4WS power steering devices, etc. Regarding.

(Prior art) Conventionally, this type of high-frequency current-carrying induction coil has a fifth
As shown in the figure, the two surfaces on which the rack teeth 31 and 32 of the steering rack shaft 3 are formed face the part to be hardened 30 which has a substantially V-shape, and two flat plate-shaped surfaces having a substantially similar V-shape are formed. It has coils 51 and 52, and a pair of current-carrying chips 53a and 53b that are provided at the longitudinal ends of each coil so as to protrude so as to abut both ends of the hardened part 30 and are insulated from each other, and the coil surface has a A large number of ejection holes 54 are provided to eject quenching cooling water. Then, high-frequency current is supplied to the part to be hardened 30 from two electrodes insulated by a Teflon plate, one from the coils 51 and 52 through the chip 53a, and the other through the chip 53b on the other side, for energization and induction. Therefore, the part to be hardened 30 is heated,
Cooling water is poured from the jet holes 54 to perform hardening.

(Problem to be solved by the invention) Regarding the conventional high-frequency current-carrying induction coil, the sixth
As shown in the figure, the hardened part 30 is
The magnetic flux density increases at the top 30a and the bottom portions 30b, 30b, and the quenched hardened layer L is formed deeper than other parts. This caused the entire part 3 to be bent and the tooth trace of the hardened part 30 to be distorted.

The present invention was devised in view of the above-mentioned problems, and prevents the hardened layer at the top and both bottoms of the hardened part from penetrating deeply, preventing bending of the steering rack shaft and distortion of the rack tooth trace. The purpose of the present invention is to provide a high-frequency current-carrying induction coil that can eliminate this problem.

(Means for Solving the Problems) In order to achieve the above object, a high frequency energized induction coil for a steering rack shaft of the present invention is provided with a covering whose two surfaces forming the rack teeth of the steering rack shaft form a substantially V-shape. V facing the hardened part and having a substantially similar shape
It has two flat coils forming a shape, and an energizing tip protruding from the longitudinal end of each coil so as to be mutually insulated and in contact with both ends of the part to be quenched. In addition to interposing a magnetic flux blocking member such as ferrite between the inner edges of the coil,
The coil is characterized in that a stepped portion or a slope portion extending away from the hardened portion is provided near the outer edge of the surface of the coil.

(Function) In the high-frequency energized induction coil for the steering rack shaft having the above configuration, the part to be hardened in which the rack teeth are formed is directly supplied with a high-frequency current through the energizing chip, and also receives electromagnetic induction by the facing coil. Heated to high temperatures. However, when electromagnetic induction is caused by the coil, the magnetic flux passing through the top of the part to be hardened is blocked and reduced by a magnetic flux blocking member such as ferrite interposed between the inner edges of the coil to cancel the edge effect. As the heated layer becomes shallower,
The magnetic flux passing through both skirts of the part to be hardened is also reduced by the distance from the part to be hardened due to the stepped or sloped part in the vicinity of the outer edge of the coil, thereby canceling out the edge effect and increasing the temperature. The layer becomes shallower. By supplying a high-frequency current for a predetermined period of time, the high-temperature layer formed at a substantially uniform depth over the entire surface of the part to be hardened as described above is formed as shown in Figures 4a and b when cooling water is supplied.
This results in a hardened layer with a uniform depth as shown in .

The formation of the hardened layer with a uniform depth prevents the steering rack shaft from bending and the rack teeth from becoming distorted.

(Example) An example of the present invention will be described below with reference to the drawings.

In Fig. 1 and Fig. 2, the high frequency energized induction coil 1 of the 4WS power steering rack shaft is
It faces the hardened part 30 of the steering rack shaft 3 for 4WS, which has rack teeth 31 and 32 for front wheel steering and rear wheel steering, respectively, formed on two surfaces forming an approximately V shape with an apex angle of approximately 80°, and is approximately similar. Two copper plate-shaped coils 11 and 12 forming a V-shape are provided, and Teflon plates 14 are provided at the longitudinal ends of these coils 11 and 12 so as to abut on both ends of the part to be hardened 30, respectively. A pair of current-carrying chips 13a, 13 insulated by
It has b. One chip 13a is fixed to a copper end plate 16 with a stopper F, and a pair of copper electrodes 15a, 15b are insulated by the same Teflon plate 14.
The chip 13b is electrically connected to the electrode 15a forming the inner end plate on the same one side via the coils 11, 12 and the end plate 16, and the other chip 13b is connected directly to the electrode 15b forming the outer end plate on the other side. These chips 13a, 13b and coils 11, 12 are supplied with high frequency current from the outside via electrodes 15a, 15b. The chips 13a, 13b protrude upward and laterally by approximately 2 mm from the heating surfaces 11a, 12a of the coils 11, 12.

The high frequency current induction coil 1 includes the coil 11,
12. A water chamber W is formed inside by the end plate 16, the inner electrode 15a, the plastic side plates 17, 17 facing the inner electrode 15a, and the plastic bottom plate 18. Quenching cooling water is supplied to the water chamber W.

The coils 11 and 12 have an end plate 16 and an inner electrode 15.
A and the side plate 17 are fastened watertight with fasteners F. A ferrite core 20 as a magnetic flux blocking member is interposed between the lower inner edges of these coils 11 and 12 forming a V shape, and blocks the electromagnetic induction effect by the lower inner edges of the coils 11 and 12. The concentration of magnetic flux on the edge top portion 30a due to this effect is reduced. In addition, the coil 11,
Step portions 11b and 12b having a depth of approximately 2 mm are provided in the vicinity of the outer edges of the surfaces 11a and 12a of the surfaces 11a and 12a in the direction away from the part to be hardened 30.
Bottom portion 30 of the part to be hardened 30 facing b, 12b
By reducing the electromagnetic induction effect on the edges 30b and 30b, and reducing the concentration of magnetic flux at the edge tops 30b and 30b due to the edge effect, the top 30a and both bottom portions 30b and 30b are made the same as the other parts, as shown in FIG. 4a. Uniform the depth of the hardened layer. The uniformity of the quenched hardened layer is
This is mainly carried out at the tooth bottom, but by combining the electromagnetic induction effect and the direct energization effect of high-frequency current, the entire rack teeth 31 and 32 are uniformly heated to a high temperature as shown in Fig. 4b, and the cooling water is supplied. This results in uniform hardening. Surfaces 11a, 1 of coils 11, 12
2a, three rows of cooling water ejection holes H are bored in a diffuser shape so as to diffuse the ejected water.

Instead of the stepped portions 11b and 12b, as shown in FIG.
It is possible to adopt a configuration in which sloped portions 11c and 12c are provided so as to move away from the part to be hardened 30 toward the outer edge, and a hardened layer L having a uniform depth as shown in FIGS. 4a and 4b can be obtained. I can do it. Although inclined processing is difficult to process, it is possible to uniformize the hardened layer L accurately.

By the way, with this high-frequency current-carrying induction coil 1,
Anode voltage for 30φmm rack shaft 3 of S45C
After applying a high frequency current of 13.5 KV and an anode current of 16.5 A for 3.5 seconds, cooling water was supplied at a flow rate of 120/min for 8 seconds to perform quenching. The depth of the hardened layer L at the hem can be reduced from 1.5mm to 0.9mm, and the other parts have the same hardened layer L of 0.8mm from the tooth bottom as before. was able to form. As a result, the occurrence of bending of the rack shaft 3 and tooth trace distortion of the rack teeth 31 and 32 was prevented.

(Effect of the invention) According to the high frequency energized induction coil for the steering rack shaft of the present invention configured as described above, the magnetic flux blocking member interposed between the inner edges of the coil and the area near the outer edge of the coil surface The thickening of the quenched hardened layer due to the edge effect at the top and both skirts of the hardened part of the easy shaft can be reduced by the stepped part or sloped part formed so as to move away from the hardened part. It is possible to prevent the occurrence of shaft bending and tooth trace distortion of the rack teeth with a simple configuration.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the high-frequency energized induction coil of the steering rack shaft of the present invention and the rack shaft, Fig. 2 is a schematic diagram for explaining the essential parts, and Fig. 3 is for explaining the main parts showing a modification of the coil. Schematic diagrams, Figures 4a and 4b are explanatory cross-sectional views and explanatory partial longitudinal cross-sectional views showing the formation status of the quenched hardened layer, Figure 5 is an explanatory schematic diagram of the high frequency current induction coil, and Figure 6 is It is an explanatory cross-sectional view showing the formation situation of the same quench hardened layer. Explanation of the symbols: 1... High-frequency energized induction coil of steering rack shaft, 3... Steering rack shaft, 11, 12... Coil, 11a, 12a...
Coil surface, 11b, 12b... step part, 11c, 1
2c... Gradient portion, 13a, 13b... Current carrying chip, 20... Magnetic flux blocking member, 31, 32... Rack teeth.

Claims (1)

[Claims for Utility Model Registration] 1. Rack teeth 31, 3 of steering rack shaft 3
The two surfaces formed with 2 face the part 30 to be quenched which has a substantially V shape, and the 2 faces have a substantially similar V shape.
two flat coils 11 and 12, and each coil 1
A pair of current-carrying chips 13a, 1 are provided at the longitudinal ends of 1, 12 in a mutually insulated state and protrude so as to abut both ends of the part to be hardened 30.
3b, a magnetic flux blocking member 20 is interposed between the inner edges of the coils 11 and 12, and the coil 1
Step portions 11b, 12b that move away from the part to be hardened near the outer edges of the surfaces 11a, 12a of Nos. 1 and 12.
Alternatively, a high-frequency current-carrying induction coil for a steering rack shaft is characterized in that gradient portions 11c and 12c are provided. 2. The coil according to claim 1, wherein the magnetic flux blocking member 20 comprises a ferrite core. 3. The coil according to claim 1, wherein the steering rack shaft 3 is a power steering rack shaft for 4WS.