Metal deforming – By tool-couple pressing together adjacent surface portions...
Reexamination Certificate
1999-07-14
2001-05-01
Butler, Rodney C. (Department: 3725)
Metal deforming
By tool-couple pressing together adjacent surface portions...
C072S135000
Reexamination Certificate
active
06223574
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a thin-walled ring member to be rotated at higher speeds and a method for producing the same. The thin-walled ring member may be applied, for example, to a friction plate mounted, for example, on a transmission of an automobile.
BACKGROUND OF THE INVENTION
A friction plate is used, in a transmission gear, for example, of an automobile, to allow a clutch-side and a gear-side to be rotated in a synchronous fashion, in order to prevent any shock upon gear shifting.
A conventional friction plate has been manufactured by a method comprising: punching a steel plate into an ring-like or annular body by means of a press machine, or coiling a web of steel plate so as to cause the broader surface to be extended in a common plane; cutting the superposed portions to form opposite ends; and then welding the opposite ends together.
It is noted, however, that a large amount of mills ends are produced during punching operation by means of a press machine, whereby loss of material is increased. Thus, the punching method is not advantageous in terms of manufacturing cost.
It is also noted that, according to the coiling method, it is necessary for weld overlays to be removed after welding, so as to obtain a plain surface. Thus, finishing works, such as grinding and/or buffing should be performed, whereby process step are complicated. When the opposite ends are not welded together so as to be remained “un-fixed”, no finishing works are required. It is noted, however, that a friction plate is meshed with a gear incorporated in a transmission and rotated at higher speeds (at a maximum speed of about 8,000 rpm). Thus, the friction plate would be expanded in its outer diameter due to a centrifugal force, when the opposite ends of the friction plate are not connected together. This causes deficiency in that the friction plate will be in contact with a part around it.
A main object of the invention is to reduce or eliminate loss or waste of material and to reduce manufacturing cost.
SUMMARY OF THE INVENTION
A thin-walled ring member according to the invention is a thin-walled ring member having a broader surface oriented in the radial direction for use as a rotatable object, which comprises a sheet of strip material of metal coiled, with the broader surface thereof being oriented in the radial direction, so as to have opposite ends, the opposite ends being connected by means of a joint, the joint including a pair of concave and convex portions adapted to be engaged with each other against a repulsive force in the circumferential direction.
The joint is constituted by the opposite ends of the sheet of strip material which are interfit with each other, or the joint is constituted by an opening formed in the sheet of strip material so as to extend over the opposite ends of the sheet of strip material, and a joint member press-fit into the opening.
The strength of the thin-walled ring member may be further increased, when a circumferential groove is formed in the narrower surface on one or both of the inner and outer peripheries of the coiled sheet of strip material, the opposite ends of the sheet of strip material being connected by a weld located in the circumferential groove.
The thin-walled ring member may be used as a friction plate, when the ring member is formed, on one or both of the inner and outer peripheries thereof, with teeth for engagement with a gear of a transmission.
The thin-walled ring member may be produced by a method which comprises the steps of: coiling a sheet of strip material of metal, with the broader surface thereof being oriented in the radial direction, so as to cause the forward end of the broader surface to be superposed on the succeeding broader surface; cutting the superposed portions of the sheet of strip material by means of a press operation, so as to form a pair of concave and convex portions on the cut ends of the sheet of strip material, the concave and convex portions being adapted to be engaged with each other against a repulsive force in the circumferential direction; and interfitting the pair of concave and convex portions with each other by means of a pressing pressure, so as to cause the opposite cut ends to be connected together.
The thin-walled ring member may also be produced by a method which comprises the steps of: coiling a sheet of strip material of metal, with the broader surface thereof being oriented in the radial direction, so as to cause the opposite ends of the sheet of strip material to be placed in a butt relationship; forming in the sheet of strip material an opening extending over the opposite ends of the sheet of strip material, the opening having a circumferentially central portion of a reduced dimension; and press-fitting into the opening a joint member having a configuration substantially the same as that of the opening, so as to cause the opposite ends to be connected together.
A friction plate may be produced by punching one or both of the inner and outer peripheral portions of the thin-walled ring member obtained in the above, so as to form teeth for engagement with a transmission gear.
In accordance with the invention, the opposite cut ends of the ring member are connected together by means of a joint including a pair of concave and convex portions adapted to be engaged with each other against a repulsive force in the circumferential direction. Accordingly, the ring member is prevented from expanding in its outer diameter, even when it is subjected, for example, to a centrifugal force during high-speed running thereof. It is also noted that a welding operation, as well as a grinding operation and a buff operation associated therewith, may be eliminated. Thus, the process step may be simplified. The ring member is formed by means of a coiling operation, so that waste of material is eliminated, thus a significant advantage may be provided in terms of reduction in cost of material.
A friction plate having high accuracy in terms of concentricity may be produced by punching one or both of the inner and outer peripheral portions of the thin-walled ring member, so as to form teeth for engagement with a transmission gear.
REFERENCES:
patent: 4896414 (1990-01-01), Hafner
patent: 5208973 (1993-05-01), Sawdon
patent: 5267383 (1993-12-01), Sawdon
patent: 52-29464 (1977-03-01), None
patent: 61-195719 (1986-06-01), None
Kataoka Kazuo
Teratoko Keiichiro
Arent Fox Kintner & Plotkin & Kahn, PLLC
Butler Rodney C.
Suncall Corporation
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