DESCRIPTION
METHOD OF PRODUCING ONE-WAY CLUTCH
TECHNICAL FIELD
This invention relates generally to a method of producing a one-way clutch. More particularly, it relates to a method of producing a one-way clutch which includes a shaft member, an outer race disposed on an outer circumference side of the shaft member and having a plurality of pocket portions provided on an inner circumferential face thereof in such a manner as to be concave toward the outer circumference side, and a roller and a resilient member accommodated in each of the pocket portions .
BACKGROUND ART A one-way clutch of the type described includes a shaft member, an outer race disposed on an outer circumference side of the shaft member and having a plurality of pocket portions provided on an inner circumferential face thereof in such a manner as to be concave toward the outer circumference side, and a roller and a resilient member accommodated in each of the pocket portions . A one-way clutch having such a configuration as just described is produced by performing broaching for a disk-type blank to form a plurality of pocket portions and a through-hole, into which a shaft member is to be fitted, in the disk-type disk-shaped blank to complete an outer race, assembling rollers and resilient members into the pocket portions and then fitting the outer race with the shaft member.
In the production of an outer race of a one-way clutch
described above, a plurality of broaches is used to formthe pocket portions, and therefore, the number of man-hours is great.
The subject of the present invention resides in provision of a method of producing a one-way clutch by which the number of man-hours for working an outer race can be reduced.
DISCLOSURE OF THE INVENTION According to an aspect of the present invention, there is provided a method of producing a one-way clutch which includes a shaft member, an outer race disposed on an outer circumference side of the shaft member and having a plurality of pocket portions provided on an inner circumferential face thereof in such a manner as to be concave toward the outer circumference side, and a roller and a resilient member accommodated in each of the pocket portions, the method comprising: a preparation step of providing a disk- shaped blank; a preforming step of performing cold presswork on the disk-shaped blank to reduce the thickness of the disk-shaped blank; a forming step of performing cold presswork on the disk- shaped blank subsequently to the preforming step to form a through-hole into which the shaft member is to be fitted and the pocket portions in the disk-shaped member to complete the outer race; and an assembling step of assembling the rollers and the resilient members into the pocket portions and fitting the outer race with the shaft member. The one-way clutch production method is characterized in that cold presswork (forming step) is performed on a disk-shaped blank to produce an outer race. By this, the number of man-hours
can be reduced when compared with that of a conventional method wherein a plurality of broaches are used to form an outer race. Desirably, the outer race has retaining portions formed thereon for retaining the rollers and the resilient members so as not to come off from the pocket portions to the inner circumference side of the outer race.
With this arrangement, since the retaining portions can be formed together with the through-hole and the pocket portions at the forming step evenwhere the outer race has a complicated shape, the number of man-hours does not increase at all.
BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of the present invention will be described in detail below, by way of example only, with reference to the accompanying drawings, in which:
FIG. 1 is a schematic sectional view of a one-way clutch according to an embodiment of the present invention;
FIG.2 is an enlarged view showing a portion around a pocket portion of FIG. 1; FIG. 3 shows side face of a disk-shaped blank for illustrating a preparation step in the one-way clutch production;
FIG. 4 shows the side face of the disk-shaped blank for illustrating a pre-forming step in the one-way clutch production;
FIG. 5 shows an outer race for illustrating a forming step in the one-way clutch production;
FIG.6 shows rollers and resilient members assembled in the outer race for illustrating an assembling step in the one-way
clutch production; and
FIG.7 is an enlarged view showing a portion around a pocket portion of FIG. 6.
BEST MODE FOR CARRYING OUT THE INVENTION
Reference is now made to FIG.1 showing in section a one-way clutch 1 according to an embodiment of the present invention. ( 1) Configuration
The one-way clutch 1 shown in FIG.1 comprises a shaft member 11, an outer race 12, rollers 13, resilient members 14, and a lid member 15.
The shaftmember 11 is a cylindrical member for transmitting a torque to the outer race 12.
The outer race 12 is an annular member metal and has a through-hole 12a formed at a center thereof for engaging with the shaft member 11, a plurality of pocket portions 21 (six in the illustrated embodiment) provided in an equidistantly spaced relation from each other in a circumferential direction on an inner circumferential face thereof in such a manner as to be concave toward the outer circumference side, and retaining portions 22, 23 (refer to FIG. 2) provided at edge portions of each of the pocket portions 21 in the circumferential direction in such a manner as to make the opening width of the pocket portion
21 smaller. Further, on the concave face of each of the pocket portions 21, an inclined face 21a is formed such that the distance between the concave face of the pocket portion 21 and the outer circumferential face of the shaft member 11 decreases toward one
side in the circumferential direction (left side on the plane in
FIG. 2).
Each of the rollers 13 is a cylindrical member provided corresponding to the inclined face 2la in the corresponding pocket portion 21 and is interposed between the shaft member 11 and the outer race 12 to transmit torque between them.
Each of the resilientmembers 14 is formed from, for example, an accordion spring formed by bending a plate-like member made of a metal and is provided so as to bias the corresponding roller 13 in the direction in which the distance between the corresponding inclined face 21a and the outer circumferential face of the shaft member 11 decreases.
The lid member 15 is a member for covering the outer circumferential face of the outer race 12 and the pocket portion 21.
(2 ) Operation
Operation of the one-way clutch 1 is now described with reference to FIG. 1.
First, when the shaft member 11 rotates in a direction indicated by an arrow mark R relative to the outer race 12 , then each of the rollers 13 moves toward the R side of the corresponding pocket portion 21. Consequently, the roller 13 is bitten between the inclined face 21a of the pocket portion 21 and the outer circumferential face of the shaft member 11 to place the shaft member 11 and the outer race 12 into a mutually locked state. Consequently, the torque of the shaft member 11 is transmitted to the outer race 12 through the rollers 13.
On the contrary, when the shaft member 11 rotates in the direction opposite to the R direction relative to the outer race 12, each of the rollers 13 moves to the side opposite to the R side of the corresponding pocket portion 21 against the biasing force of the corresponding resilient member 14. Consequently, a gap is formed between the inclined face 21a of the pocket portion 21 and the outer circumferential face of the shaft member 11 thereby to place the shaft member 11 and the outer race 12 into a mutually free state. Consequently, the shaft member 11 rotates but idly and the torque transmission is interrupted. (3) Production Method
A method of producing the one-way clutch 1 is described. The method of producing the one-way clutch 1 comprises the following steps: 1. Preparation Step
In this step, a metal blank such as a round bar is cut to provide a disk-shaped blank 31 from which the outer race 12 is to be formed (see FIG. 3) .
2. Preforming Step At this step, cold presswork is performed on the disk-shaped blank 31 to reduce the thickness of the disk-shaped blank 31 approximately to the thickness of the outer race 12 after it is formed. By the cold presswork, lines or swells on the surface of the skin of the disk face of the disk-shaped blank 31 can be reduced (refer to FIG. 4).
3. Forming Step
A metal die having a shape with which the through-hole 12a
into which the shaft member 11 is to be fitted, the pocket portions
21 and the retaining portions 22, 23 can be blanked at a time is used to perform cold stamping for the disk-shaped blank 31 to complete the outer race 12 (see FIG. 5). 4. Assembling Step
The resilient members 14 are assembled into positions of the pocket portions 21 of the outer race 12 at which the inclined faces 21a are not formed, and then the rollers 13 are pushed into the resilient members 14 at positions corresponding to the inclined faces 21a (refer to FIG. 6). Consequently, as shown in
FIG. 7, the rollers 13 and the resilient members 14 are retained by the retaining portions 22, 23 so that they do not come off to the inner circumference side of the outer race 12. Then, the outer race 12 is finally fittedwith the outer circumference of the shaft member 11, thereby completing the one-way clutch 1 (see FIG. 1) .
(4 ) Characteristics
Characteristics of the one-way clutch of the present embodiment are now described.
1. Reduction of the number of man-hours by the presswork of a disk-shaped blank
In the method of producing the one-way clutch 1 in the present embodiment, the outer race 12 is produced by stamping (cold presswork) with a metal mold. Therefore, the number of man-hours can be reduced when compared with that of a conventional production method wherein a plurality of broaches are used. Further, since also the retaining portions 22, 23 can be formed simultaneously, the number of man-hours forworkingthe outer race
12 does not increase at all.
2. Prevention of coming off of the rollers and the resilient members from the pocket portions
In the one-way clutch 1 in the present embodiment, since the retaining portions 22, 23 are formed on the inner circumferential portions of the outer race 12 , the rollers 13 and the resilient members 14 are retained so that they may not come off from the pocket portions 21 to the inner circumference side of the outer race 12. Therefore, even when the outer race 12 is fitted with the outer circumference of the shaft member 11 which is disposed in a horizontal direction at the assembling step, the rollers 13 and the resilient members 14 do not come off f om the pocket portions 21 at all.
(5) Other Embodiments While an embodiment of the present invention has been described above, the particular configuration or arrangement is not limited to that of the embodiment. The arrangement can be modified without departing from the spirit of the present invention. For example, the shape of the retaining portions is not limited to that of the present embodiment.
INDUSTRIAL APPLICABILITY
The one-way clutch production method according to the present invention can reduce the number of man-hours because an outer race is produced by cold presswork of a disk-shaped blank. Thus, the present invention is useful in the power machine industry.