JP2007268573A - Method for manufacturing arcuate coil spring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily form an arcuate coil spring from a straight coil spring. <P>SOLUTION: In a method for forming the straight coil spring into an arcuate shape, the spring is held in a curved state by inserting an arcuate core bar into the side of the inside diameter of a coil and heat treatment is performed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method of manufacturing an arc coil spring used for, for example, a clutch disk.

  A conventional arc spring is manufactured by a method in which a wedge-shaped jig is driven between the pitches on the outer peripheral side of the linear coil spring 3 in a cold state to forcibly spread it into an arc shape, or in an arc-shaped groove. There is a method of forming an arc shape by fitting a linear coil spring and performing a heat treatment.

Patent Documents 1-17 are documents that disclose conventional manufacturing methods.
JP-A-01-027290 Japanese Utility Model 05-05339 JP 07-001065 A JP 08-004835 A JP 08-0935852 JP 08-105508 A JP 08-121535 A JP 08-135704 A JP 08-224632 A JP-A-10-237546 JP-A-11-019743 11-500668 JP 2000-129359 A JP2003-181581 WO 91/06785 USP 5052664 EP 058474474A1

  However, forming with a wedge-shaped jig has poor workability, and the wedge-shaped jig may damage the surface of the coil spring, leading to a decrease in durability. Further, the method of fitting the linear coil spring into the arc-shaped groove has a drawback that the apparatus becomes large. Furthermore, it is difficult to form both with a constant radius of curvature so as to fit into the spring groove 2. If the arc-shaped coil spring 4 is not formed with a constant radius of curvature, the frictional resistance with the coil spring groove 2 is increased and the function as a clutch may not be exhibited.

  According to the present invention, the above-mentioned problem is characterized in that, in the method of forming a linear coil spring into an arc shape, the spring is kept in a curved state by inserting an arc-shaped cored bar on the inner diameter side of the coil and heat-treated. This is solved by providing a manufacturing method.

  For example, a first heat treatment step of heating a linear coil spring at a predetermined temperature and time prior to arc forming, a step of grinding a spring end prior to arc forming, and arcing a linear coil spring Shot peening etc. after the arc forming process after the arc forming process to keep the spring in a curved state by inserting an arc cored bar on the inner diameter side of the coil And a step of low-temperature annealing the coil spring after completion of this step at a predetermined temperature and time.

  According to the manufacturing method of the present invention, an arc-shaped coil spring having a constant radius of curvature can be easily obtained as a final product by setting the radius of curvature of the arc-shaped cored bar to an optimum shape without applying excessive force.

Embodiment of the Invention

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows an arc coil spring made according to the present invention.

  FIG. 2 shows a state in which the arc-shaped metal core 5 is inserted into the linear coil spring 3 according to the manufacturing method of the present invention.

  For example, as shown in FIG. 4, a torque transmitting clutch disk is provided with arc-shaped spring grooves 2 for attaching a plurality of coil springs 3. As shown in FIG. 2, the coil spring 3 to be inserted into the groove is predetermined in a state in which an arc-shaped cored bar 5 is inserted on the inner diameter side of the linear coil spring 3 so as to fit the spring groove 2. A step of performing a low temperature annealing treatment at a temperature and a time of time, a step of performing a strengthening treatment such as shot peening after arc forming, and a low temperature annealing treatment of the coil spring 4 that has completed the above steps at a predetermined temperature and time. The arc-shaped coil spring 4 is formed by the process of applying. As the cross section of the arc-shaped metal core 5, any cross section such as a round line or a rectangular cross section can be used.

  Further, when the arc-shaped coil spring 4 is formed with the arc-shaped cored bar having a constant radius of curvature, the radius of curvature at both ends becomes larger than that of the central portion, and an arc-shaped coil spring having a constant curvature cannot be formed. As shown in FIG. 3, the curvature radius R of the end portions 5b and 5c on both sides of the arc-shaped metal core 5 is previously formed to be smaller than the curvature radius R of the central portion 5a in advance, thereby having a constant curvature radius. An arc coil spring 4 can be formed.

  Further, since the linear coil spring 3 is only constrained on the plane of the arc-shaped metal core 5 and is not constrained in the circumferential direction of the coil spring, a stable arc-shaped coil spring 4 with good flatness can be formed.

The figure which shows the arc-shaped coil spring manufactured by this invention. The figure which shows the arc shaping | molding (core metal insertion) state of this invention. The figure which shows the curvature radius of a metal core. The front view of a clutch disk.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Clutch disc 2 Spring groove 3 Coil spring 4 Arc-shaped coil spring 5 Arc-shaped metal core 5a Center part 5b of metal core End 5c of metal core End of metal core

Claims (7)

  A method of forming a linear coil spring into an arc shape, wherein an arc-shaped cored bar is inserted on the inner diameter side of the coil to heat the spring while keeping it in a curved state.   The manufacturing method according to claim 1, wherein a radius of curvature of the cored bar used at the time of arc forming is temporarily reduced toward the end of the quantity compared to the central part of the coil spring.   The heat treatment performed during the arc forming corresponds to a low temperature annealing process, wherein the temperature is about 350 ° C to 450 ° C and the time is 30 minutes to 60 minutes. The manufacturing method of any one of Claims.   Prior to the arc forming, the linear coil spring is subjected to a first heating step. The manufacturing method according to any one of claims 1 to 3, wherein the first heating step is about 200 ° C to 250 ° C and the time is 20 minutes to 30 minutes.   The manufacturing method according to any one of claims 1 to 4, wherein a grinding step of a spring end is performed prior to the arc forming.   The manufacturing method according to any one of claims 1 to 5, further comprising a strengthening process step such as shot peening and a low-temperature annealing step after the arc forming step.   In the arc forming described above, the arc cored bar and the spring inserted into the coil inner diameter side of the spring are not fixed, but are rotatable with respect to changes in the number of turns of the spring and the coil diameter caused by the heat treatment. The manufacturing method according to claim 1.

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