Metal working – Means to assemble or disassemble – Puller or pusher means – contained force multiplying operator
Patent
1989-07-26
1991-01-22
Echols, P. W.
Metal working
Means to assemble or disassemble
Puller or pusher means, contained force multiplying operator
192 89B, 267161, B23P 1300
Patent
active
049859730
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a manufacturing method for a diaphragm spring for use in a clutch for a vehicle etc.
BACKGROUND ART
Conventionally, when manufacturing a diaphragm spring for use in a clutch cover assembly; plural holes 32 and slits 33 have been punched out from a disc-like metal blank 31 by a first press work as illustrated by FIG. 6, and then a circular center hole 34 has been punched out as shown in FIG. 7 by a second press work. Thereafter the blank has been bent to a specified shape as illustrated by FIG. 8. This diaphragm spring is elastically deformed by being pushed and pulled by a release bearing 36 at inner peripheral parts of fingers 35 formed of the slits 33 to cause a clutch disc to be pressed on and separated from a flywheel through, for instance, a pressure plate.
In the conventional manufacturing method, it has been impossible to make a width of the slit 33 smaller than the plate thickness of the blank 31. Furthermore, contact area between an inner peripheral part of the finger 35 and a release bearing 36 is small because of the reduced inner peripheral width of the finger 35 causing a high bearing pressure. With the high bearing pressure the inner peripheral part of finger 35 has worn out quickly.
DISCLOSURE OF THE INVENTION
In order to solve the foregoing problem, this invention provides a manufacturing method for a diaphragm spring in which, when making a center hole at a central part, making plural rectangular holes on an outer peripheral part with specified spaces left therebetween in a circumferential direction, forming plural ligulated fingers radially by means of plural radial slits extending from the rectangular holes to the center hole, and manufacturing the disc-like diaphragm spring wherein inner peripheral parts of these fingers are pressed by a release bearing; two processes are involved: a first process for punching the peripheral holes and slits out of a disc-like blank by a press work and a second process for punching out the center hole by using a gear-shaped press die having circular tip portions spaced at the same spacing as that of the slits. A blank inner peripheral side end of each slit, opposite, is formed into a tapered shape in punching out the rectangular holes and slits. An angular position of the circular tip portion of the press die is aligned with that of the tip ends of the tapered shape of the slits in the process for punching out the center hole.
According to the above-mentioned method, the blank inner peripheral side end of each slit along the longitudinal sides thereof, is formed into the tapered shape in the punching process for punching out the rectangular holes and slits. The position of the circular tip portion of the press die is aligned with that of the tip ends of the tapered shape of the slits in the process for punching out the center hole. Therefore, the inner peripheral part of the finger formed between the slits has a large width so that the bearing pressure can be reduced because of the large contact area with the release bearing. Thus, the wear is reduced and the durability improved in the manufactured diaphragm spring.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front view of a diaphragm spring obtained by the manufacturing method in an embodiment of the present invention.
FIG. 2 through FIG. 5 are explanatory views for a manufacturing method of a diaphragm spring of the present invention.
FIG. 6, and FIG. 7 and FIG. 8 are explanatory views for a manufacturing method for a conventional diaphragm spring.
BEST MODE FOR CARRYING OUT THE INVENTION
In FIG. 1 which is the front view of the diaphragm spring formed by the manufacturing method in the embodiment of the present invention, a center hole 1 is made at a central part of a disc-like diaphragm spring, and plural rectangular holes 2 are made at an outer peripheral part thereof with specified spaces left therebetween on the same circumference. Slits 3 extending from the rectangular holes 2 to the center hole 1 are formed in radial directions. The inner
REFERENCES:
patent: 3327739 (1966-03-01), Pritchard
patent: 4503696 (1985-03-01), Roeder
patent: 4571800 (1986-02-01), Faupell
patent: 4655333 (1987-04-01), Martinez-Corral
patent: 4704041 (1987-11-01), Hayashi et al.
Murata Ikuo
Yoshimura Yoshinari
Echols P. W.
Kabushiki Kaisha Daikin Seisakusho
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