JPS61136628A - Heat treatment of fork shaped parts - Google Patents

Abstract

PURPOSE:To maintain an accurate size precision of width between 2 sides of press fork, by heating the fork to quenching temp. while restraining side surface part of fork base part, and cooling the fork by making the flowing direction of coolant to coincide with longitudinal direction thereof. CONSTITUTION:An iron plate press fork 1 is inserted to the hole of a jig holder 8, held vertically, and the side surface 10a of a fork base part 10 is restrained. The fork 1 under the state is heated to quenching temp. in heating furnace. Residual stress due to working is apt to release at the part of forks 9, but since the part 10a is restrained, release of residual stress is suppressed due to dead weight, and deformation of the width (d) between 2 surfaces is suppressed. The fork 1 is quenched while being cooled rapidly by quenching oil from the state. In this case, since quenching oil flows along longitudinal direction of the fork 1, both sides thereof are cooled simultaneously. Thus, the size precision of the width (d) of the fork 9 is maintained during quenching, and the deviation can be suppressed.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention improves the heat treatment jig to produce a thin steel plate press clutch release 7f (hereinafter referred to as iron plate press fork).
This invention relates to a heat treatment method for improving the dimensional accuracy of the width across flats of fork-shaped parts such as the above.

(Prior Art) Conventionally, a heat treatment method for an iron plate press 7 oak 1 having a complicated product shape is carried out as follows. First, Figures 6 and 7
As shown in the figure, the iron plate brace forks 1 to be heat treated are arranged horizontally in a plurality of baskets 5 on a tray 2a used for the heat treatment work. Kono Basquera) 3ti) Ray 2
A plurality of beads 45 protrude from the aO column 4a via a collar 63, and the trays are divided into several shelves at predetermined intervals and placed on the tray 2a.

Next, a tray 2a for storing this iron plate press fork 1 is prepared.
is heated in an electric heating furnace, and then placed in a tray 2 in a tank of quenching oil.
Submerge and cool quickly. When the iron plate press 7 oak 1 is heated and cooled for quenching work, the quenching oil flows in the direction of arrow E shown in FIG. After this,
After the tempering work, the hardened press fork 1 inside the basket 5 is taken out.

In addition to packet-shaped heat treatment jigs for performing such heat treatment work, there is also a method of heat treatment by simply suspending an iron plate press fork. In addition, as a prior art, for example, Utility Application No. 144660/1982,
and Japanese Unexamined Patent Publication No. 145480/1983.

(Problems to be Solved by the Invention) However, in the above heat treatment method, the iron plate press fork is not constrained at all during the heat treatment. For this reason, residual stress due to the press is released during heating during heat treatment, and the accuracy of the width across flats of the fork portion is 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, in the case of horizontal installation, the front surface 1a and back surface 1b of the iron plate press 7 orifice will be in an uneven cooling state as shown in Fig. 8 during hardening, resulting in uneven hardening, and the width across flats of the iron plate press fork will not be accurate. dimensional accuracy cannot be maintained, resulting in variations.

In order to solve the above-mentioned problems, the present invention has been developed by fixing the entire cylindrical surface of an iron plate press fork with a jig holder, and preventing 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, improving dimensional accuracy, and producing inexpensive products by storing as many fork-like 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 processed from a thin steel plate with a jig holder, and 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 present invention will be explained in detail. 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 caused by the press tries to release, and a force in the β direction acts.
Since the side portion of the iron plate press fork is restrained by the jig holder, a force in the direction r is exerted by its own weight δ.

Therefore, the deformation in the β direction is suppressed by the force in the r 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 restraining 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 uniformly cooled and uneven quenching is achieved. does not occur.

(Example) Embodiments of the present invention will be described based on the drawings.

In the simplified sectional view shown in 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 the four joints and both sides of the center in the longitudinal direction. That's what happens. 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 columns 4, and furthermore, in the longitudinal direction of the tray 2! There are two night rails 7 that are integrally fitted into each of the three pillars 4 along /c.

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

The iron plate press fork 1 to be heat treated is shown in FIGS.
As shown in e), the fork 9 is a pressed fork-shaped part having a U-shaped cross section and bifurcated at one end, and has a spherical convex portion 11 in the center of the fork base 10. Further, a spherical recess 14 is formed at the center of the tip of the other end 13 extending with a constant width from the tapered part 12 of the fork base 10. This part is a two-pronged automobile 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 such a fork-like part is shown below.

First, the iron plate press forks 1t are inserted into the holes 8a of the jig holders 8 arranged on the tray 2, respectively. At this time, the iron plate press 7 orc 1 is placed in a state where it stands almost perpendicular to the jig holder ♂. As a result, the side surface 10a of the shift oak 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.

Residual stress caused by pressing is particularly likely to be released in the 7-oak 9 portion of the heated iron plate press fork 1, but since the side surface 10a is restrained by the jig holder 8,
Due to the weight of the iron plate press fork 1, a force acts in a direction that suppresses the release of residual stress, so that deformation of the width across flats d is suppressed.

From this state, quench it with quenching oil and use the iron plate press fork 1.
is quenched.

As shown in FIG. 2, the flow of cooling quenching oil, etc. flows out from the bottom of the tray 2 along the longitudinal direction of the iron plate press fork 1.
b are cooled at the same time, and the width across flats d of the fork 9 can be maintained at the dimension M degree due to quenching, and variations can be suppressed.

Test data showing this is shown in FIGS. 9 and 10.

FIG. 9 shows a case in which a conventional basket-shaped heat treatment jig is used, and FIG. 10 shows a case in which a jig holder in the heat treatment method of this embodiment is used.

The amount of change in each heat treatment (the amount of dimensional change before and after quenching) and the variation are shown.

As is clear from the results of the above data, the number of temples n=
At 45, the average value Ma decreased from 8LL2μ to 5&5μ, and the deviation σ also decreased from 212 to 140.

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 the convex portion 11 of the iron plate press fork.
It ranges from +20 dews to Ofm from the center. The total length of the iron plate press 7 oak is approximately 250 m, and the outer diameter width of the fork 9 is approximately DI-j701.

According to the heat treatment method for fork-shaped parts as described above, it is possible to reduce variations in the width across flats of the fork part to less than Σ, and as a secondary effect, when using a conventional basket-shaped jig, In comparison, since there are no obstacles that restrict the flow direction of the quenching oil, the amount of quenching oil taken out can be greatly reduced.

Further, 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 conventional case.

(Effect) As is clear from the above explanation, by restraining the entire side surface of the fork base of the fork-shaped part with the jig holder,
During heating during heat treatment, residual stress due to processing is released,
Since a force acts in the opposite direction to the force in which the fork part opens outward, the flow of quenching oil, etc. that cools the fork part does not release the residual stress in the fork part. Since it is cooled uniformly along the longitudinal direction, the dimensional accuracy of the 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 drawings]

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 acting on the iron plate press fork in Fig. 1 during heating; Fig. 4 #'' is a diagram showing the effective restraint range ξ of the jig holder in Fig. 1; Line sectional view, (d) B-B line sectional view, (al
1"t is a sectional view taken along the line C-C, FIG. 6 is a diagram showing the state of heat treatment using a conventional basket, FIG. 7 is a partial plan view shown in FIG. 6, and FIG. Fig. 9 is a diagram showing the amount of change in the width across flats due to heat treatment in the conventional example, and Figure 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 10
...Fork base 10a... Opening part Fig. 1 1--6y, xh-y '8--
-Sandai4kirua'. Fig. 2 Fig. 3 Fig. 4 Fig. 5

Claims (2)

[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 the quenching temperature without releasing the residual stress caused by processing,
Next, a method for heat treating a fork-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 is vertically inserted into the hole of the jig holder with the fork-shaped part of the fork-shaped part facing upward. However, the side portions of the fork-shaped parts are restrained by their own weight.