JPS647137B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention improves the heat treatment jig to improve the width across flats of fork-shaped parts such as press clutch release forks made of thin steel plates (hereinafter referred to as iron plate press forks). This invention relates to a heat treatment method that improves accuracy.

(Conventional technology) Conventionally, iron plate press fork 1 has a complicated product shape.
The heat treatment method is carried out as follows. First, as shown in FIGS. 6 and 7, the iron plate press forks 1 to be heat treated are placed horizontally in a plurality of baskets 3 on a tray 2a used for the heat treatment work. This basket 3 has a plurality of beams 5 extending from the supports 4a of the tray 2a through collars 6a.
Accordingly, the tray 2a is divided into several shelves at predetermined intervals and placed on the tray 2a.

Next, the tray 2a containing the iron press fork 1 is heated in an electric heating furnace, and then the tray 2a is submerged in a tank of quenching oil to be rapidly cooled. When the iron plate press fork 1 is heated and cooled for quenching, the quenching oil flows in the direction of arrow E shown in FIG. Thereafter, after a tempering operation, the hardened press fork 1 in the basket 3 is taken out.

In addition to bucket-shaped heat treatment jigs for carrying out such heat treatment operations, there is also a method of heat treatment by simply hanging an iron plate press fork. Further, as prior art, for example, there are Utility Model Application No. 144660/1982 and Japanese Patent Application Laid-open No. 145480/1983.

(Problems to be solved by the invention) However, in the above heat treatment method,
Steel plate press forks are not subject to any restrictions during heat treatment. For this reason, residual stress due to the press was released during heating during heat treatment, and the accuracy of the width across flats of the fork portion was unstable, making it impossible to obtain the required dimensions. Annealing can be used to remove this residual stress, but this requires a two-step heat treatment process, which poses problems in terms of workability and cost.

In addition, when placed horizontally, the front surface 1a and back surface 1b of the iron plate press fork will be in an uneven cooling state as shown in Fig. 8 during hardening, resulting in uneven hardening, and the exact width across flats of the iron plate press fork will not be accurate. Accuracy cannot be maintained and variations occur.

In order to solve the above-mentioned problems, the present invention restrains the side parts of the iron plate press fork with a jig holder, and prevents uneven hardening due to uneven cooling during hardening, thereby increasing the width across flats of the iron plate press fork. To provide a heat treatment method capable of reducing heat treatment changes and variations in heat treatment, improving dimensional accuracy, and producing inexpensive products by storing as many fork-shaped parts as possible within a determined tray dimension. With the goal.

(Means for Solving the Problems) In order to achieve the above object, the heat treatment method of the present invention restrains the side surface of the fork base of a fork-shaped part to be processed from a thin steel plate with a jig holder. It is characterized in that it is heated to the quenching temperature without releasing the residual stress caused by machining, and then cooled with the longitudinal direction of the component aligned with the flow direction of the cooling liquid.

(Function) Next, the function of the present invention will be explained. An iron plate press fork is inserted into the installation hole of a jig holder installed between supports on a tray used for heat treatment work, and the side surface of the fork base is restrained.

When heated in this state, as shown in Figure 3,
The residual stress from the press tries to release, and a force in the β direction acts, but since the sides of the steel plate press fork are restrained by the jig holder, its own weight δ
, a force in the γ direction acts.

Therefore, the deformation in the β direction is suppressed by the force in the γ direction, and the dimensional accuracy of the width across flats of the iron plate press fork is improved.

In addition, the heated iron plate press fork is set perpendicularly to the restraint holder, and the quenching oil flows in the direction of arrow H shown in Figure 2, so that both the front and back surfaces are cooled uniformly, eliminating uneven quenching. Does not occur.

(Example) An example of the present invention will be described based on the drawings. In the simplified cross-sectional view of FIG. 1, the heat treatment tray 2 used in the heat treatment method of the present invention has a rectangular shape, and A total of six columns 4 are erected from both sides of the center in the direction. Moreover, the tray 2 has a grid-like frame structure, and the quenching oil flows into the tray from the bottom.

A cylindrical collar 6 of a predetermined length is inserted into each of the six pillars 4, and two side collars 6 are fitted into each of the three pillars 4 along the longitudinal direction of the tray 2. There is rail 7.

These two side rails 7 have shelf parts 7a projecting from opposite sides, and on these shelf parts 7a,
Two flat plate jig holders 8 are installed. The jig holder 8 is provided with a plurality of assembling holes 8a at predetermined positions, and a certain number of iron plate press forks 1 as fork-shaped parts are housed in each hole 8a and heat treated.

The iron plate press fork 1 to be heat treated is shown in Fig. 5a.
As shown in ~e, the fork 9 is a press-formed fork-shaped part having a U-shaped cross section and bifurcated at one end, and a spherical convex portion 11 is provided at the center of the fork base 10. In addition, the fork base 10
A spherical concave portion 14 is formed at the center of the tip of the other end portion 13 extending with a constant width from the tapered portion 12 . This part is a two-pronged auto part that disengages the clutch, and serves as a two-pronged lever that supports the release bearing and presses it against the release lever.

A method for heat treating a fork-shaped part in this manner will be described below.

First, the iron plate press forks 1 are inserted into the holes 8a of the jig holders 8 arranged on the tray 2, respectively.
At this time, the iron plate press fork 1 is placed in a substantially perpendicular state to the jig holder 8. Thereby, the side surface 10a of the fork base 10 is restrained by the hole diameter of the jig holder 8. next,
The iron plate press fork 1 in this restrained state is heated to a quenching temperature in a heating furnace.

Fork 9 of heated iron plate press fork 1
Particularly, the residual stress caused by the press work tries to be released, but since the side part 10a is restrained by the jig holder 8, the weight of the steel press fork 1 exerts a force in the direction that suppresses the release of the residual stress. Therefore, the deformation of the width across flats d is suppressed.

From this state, the iron plate press fork 1 is quenched by quenching with quenching oil.

As shown in FIG. 2, the flow of cooling quenching oil flows out from the bottom of the tray 2 along the longitudinal direction of the iron plate press fork 1, so that the front surface 1a and back surface 1b of the iron plate press fork 1 are cooled at the same time. , it is possible to maintain the dimensional accuracy of the width across flats d of the fork 9 due to hardening and suppress variations.

Test data showing this is shown in Figures 9 and 10.
As shown in the figure.

Figure 9 shows the case when a conventional basket-shaped heat treatment jig is used, and Figure 10 shows the case when the jig holder in the heat treatment method of this embodiment is used. (after dimensional change) and variations are shown.

As is clear from the above data, when the number of samples was n=45, the average value decreased from 80.2μ to 38.3μ, and the deviation σ decreased from 27.2 to 14.0.

The symbol ε shown in FIG. 4 is the effective restraint range in which the iron plate press fork 1 is restrained by the jig holder 8 used in this embodiment, and its value is +20 mm from the center of the convex part 11 of the iron plate press fork. or 0mm
is within the range of The total length of the iron plate press fork is approximately 250 mm, and the outer diameter width D of the fork 9 is approximately 70 mm.

According to the heat treatment method for fork-shaped parts as described above, the amount of heat treatment change and variation in the width across flats of the fork part can be reduced to 1/2 or less, and as a secondary effect, it is possible to reduce Compared to when in use, there are no obstacles that restrict the flow direction of the quenching oil, so the amount of quenching oil taken out can be greatly reduced.

Furthermore, the jig holder can be pulled out from both ends of the tray, and a larger amount of heat-treated parts can be hardened within a given tray size than in the prior art.

(Effect) As is clear from the above explanation, by restraining the side surface of the fork base of a fork-shaped part with a jig holder, the residual stress due to processing is released during heat treatment, and the fork part moves outward. Since a force acts in the opposite direction to the force in the opening direction, residual stress in the fork-shaped parts is not released, and the flow of cooling oil, etc., is uniform along the longitudinal direction of the fork-shaped parts. Because it cools
Dimensional accuracy of width across flats can be maintained and variations can be eliminated. Furthermore, since the flow direction of the quenching oil is not restricted, the amount of quenching oil taken out can be greatly reduced.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional state diagram showing a state in which an iron plate press fork is incorporated into a jig holder according to an embodiment of the present invention, FIG. 2 is a state diagram showing the flow direction of quenching oil in FIG. 1, Fig. 3 is a state diagram showing the direction of the force that acts on the iron plate press fork in Fig. 1 during heating, Fig. 4 is a diagram showing the effective restraint range ε of the jig holder in Fig. 1, and Fig. 5 is a diagram showing the actual restraint range ε of the jig holder in Fig. 1. An iron plate press fork according to an example is shown, a is a plan view, and b is an X
- A partial cross-sectional side view along the X-ray, c is a cross-sectional view along the line A-A, dB-B is a cross-sectional view, e is a cross-sectional view along the C-C line, and Figure 6 shows the heat treatment state using a conventional basket. 7 is a partial plan view shown in FIG. 6, FIG. 8 is a diagram showing the flow state of the quenching oil in FIG. 6, and FIG. The figure shown in FIG. 10 is a diagram showing the amount of change in the width across flats due to heat treatment in this example. 1... Iron plate press fork, 8... Jig holder, 1
0...Fork base, 10a... Side part.

Claims (1)

[Scope of Claims] 1. The side surface of the fork base of a fork-shaped part to be machined from a thin steel plate is restrained by a jig holder, and the part is heated to a quenching temperature without releasing the residual stress caused by the working of the part, Next, a method for heat treating a hook-shaped component, characterized in that cooling is performed in a state where the longitudinal direction of the component and the flow direction of the cooling liquid are aligned. 2. In the heat treatment method according to claim 1, the restraining means of the fork-shaped part in the jig holder inserts the fork-shaped part of the fork-shaped part vertically into the hole of the jig holder with the fork-shaped part facing upward; A fork-shaped part whose side parts are restrained by its own weight.