Cutting – Processes – Plural cutting steps
Reexamination Certificate
1999-05-26
2001-08-28
Goodman, Charles (Department: 3724)
Cutting
Processes
Plural cutting steps
C083S054000
Reexamination Certificate
active
06279439
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a one-way clutch cage to be used in, for example, transmissions of automobiles or the like.
Conventionally, there has been a method for manufacturing a one-way clutch cage as shown in FIGS.
4
AnF and
5
A to
5
C. In this manufacturing method, first, as shown in
FIG. 4A
, a disc
101
is punched out from a metal plate. Next, as shown in
FIG. 4B
, central part of the disc
101
is drawn by drawing process and a bottom thereof is punched out, by which a circular-cylindrical member
102
is formed. This cylindrical member
102
is composed of a cylindrical portion
103
and an outer flange
105
located at an axial end of the cylindrical portion
103
.
Next, as shown in
FIG. 4C
, a plurality of windows
107
,
107
, . . . are punched out in the cylindrical portion
103
of the cylindrical member
102
so as to be circumferentially spaced from one another with specified intervals. Subsequently, as shown in
FIG. 4D
, an outer annular part
106
ranging from the radially outermost circumference of outer flange
105
to a radially inward location, defined by a specified length from the radially innermost circumference of the outer flange
105
, towards the radially outermost circumference of the outer flange
105
is punched out of the outer flange
105
of the cylindrical member
102
.
Next, as shown in
FIGS. 4E and 5C
, four circumferential places of the cylindrical member
102
are punched from an inside of the cylindrical member to the outside thereof, so that slits
108
are formed which range across the outer flange
105
to the windows
107
. One window
107
is sandwiched by one pair of adjacent slits
108
,
108
, while another window
107
opposite to the one window
107
is sandwiched by the other pair of adjacent slits
108
,
108
.
Next, as shown in
FIG. 4F
, pillars
110
,
110
beside the windows
107
sandwiched by the aforementioned pairs of slits
108
,
108
are tilted radially outward so that a rim portion
111
sandwiched by the pairs of slits
108
,
108
respectively, protrudes radially outward. These rim portions
111
, when the one-way clutch is assembled to an outer ring (not shown), press the inner circumferential surface of the outer ring so that a cage
112
is frictionally coupled to the outer ring.
The above-described method for manufacturing a one-way clutch cage, unfortunately, has the following problems (1), (2) and (3):
(1) In the slit punch-out process of
FIG. 4E
, because a punch
200
is thrust out from the radial inside to the radial outside of the cylindrical member
102
to form the slits
108
as shown in
FIGS. 5B and 5C
, the total punching distance includes a disc thickness t plus a radial distance D of the outer flange
105
resulting after the cutout of the outer annular part
106
. Such a long punching distance causes a need for increasing the punching width in terms of the punching die life, which in turn makes the slit width wider so that another cage is more likely to be caught in this slit
108
, resulting in a disadvantage of difficulty in handling. Also, a wide slit width results in a lower strength, whereby the cage
112
becomes prone to deformation. This is a further disadvantage;
(2) As shown in
FIG. 5A
, during the slit punch-out process, there is a tendency toward the occurrence of burrs in the windows
107
. This illustrates another disadvantage; and
(3) In the slit punch-out process, because of a large slit width as described in (1) above, the windows
107
are prone to deformation so that when the cage is assembled to a one-way clutch, the sprag deteriorates in operation and the one-way clutch deteriorates in performance as a disadvantage.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a method for manufacturing a one-way clutch cage, which method allows cage slits to be punched out with a short punching distance, and in which method the slits are narrow in width and less prone to deformation.
Another object of the present invention is to provide a method for manufacturing a one-way clutch cage, in which method the slit punch-out process does not result in burrs at the windows.
In order to achieve the above objects, there is provided a method for manufacturing a one-way clutch-cage, comprising:
a slit forming step for forming slits in a cylindrical member having a cylindrical portion and an outer flange at an axial end of the cylindrical portion, so that the slits extend radially inward from a location which is radially inward from an outer edge of the outer flange by a specified distance, and also extend axially from the axial end of the cylindrical portion a specified distance; and
an outer flange cutting step for, after the slit forming step, cutting an outer annular part out of the outer flange so that the outer annular part extends from a location which is radially inner the radially outermost end of the slits by a specified distance, to a radially outermost circumference of the outer flange.
In this invention, slits are punched out before the step of cutting the outer flange. Therefore, the slits can be formed by punching out a boundary portion between the cylindrical portion and the outer flange (i.e., a portion between the later-cut outer annular part and the windows) in a radially diagonal or slanted direction from the inside of the cylindrical member toward the outside of the cylindrical member. Formation of the slits by such a radially diagonal or slanted punching operation after the cutting of the outer annular part of the outer flange as in the prior art, is impermissible because of a lack of strength of the cylindrical member that would lead to deformation thereof.
In this invention, since the diagonal punch-out is enabled, the punching distance can be shortened as compared with such horizontal punching as the prior art. This allows the punching die to be thinned in thickness and the slit width to be lessened, making it unlikely that other cages become caught in the slits, resulting in an improved handleability. Besides, by virtue of the narrowed slit width, the strength of the cage can be improved upon, and deformation of the cage can be prevented so that the one-way clutch can exhibit improved in performance.
One embodiment further comprises a window punch-out step for, after the slit forming step and before the outer flange cutting step, punching out in the cylindrical portion a plurality of windows including windows that are continuous to the slits, so that the windows are circumferentially spaced from one another with specified intervals.
In this embodiment, since the windows are formed after the formation of the slits, no burrs occur at the windows.
In one embodiment, when the slits are formed during the slit forming step, at least one cutout for chucking positioning is formed in the outer flange of the cylindrical member.
In this embodiment, in the slit forming step, at least one cutout for chucking positioning is formed. This at least one chucking positioning cutout can be used in later steps of a window punch-out process and an outer-ring cutting step. Therefore, the number of times of positioning can be reduced so that a reduction in manufacturing time as well as a simplification of processes can be achieved.
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patent: 3107566 (1963-10-01), Archer
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patent: 4998430 (1991-03-01), Howe
patent: 5078243 (1992-01-01), Kanai et al.
patent: 5553525 (1996-09-01), Mailey et al.
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Ikeda Takaaki
Kamiji Michiyuki
Maeda Hiroyuki
Numata Tetsuaki
Goodman Charles
Koyo Seiko Co. Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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