JPWO2008111118A1 - Method for manufacturing ring-shaped member - Google Patents

Abstract

The yield ratio, which is the ratio of the weight of the ring-shaped member to the weight of the material, and the yield ratio, which is the ratio of the ring-shaped member to the blank, are improved to reduce costs. In the method of manufacturing a ring-shaped member that obtains a ring-shaped member from the vertically long blank 3, the pair of connecting portions 3 b and 3 c are expanded outward from the inside of the blank 3, and the pair of arc-shaped portions 3 d are respectively outward. Then, it is pressed inward and expanded to form a ring-shaped member.

Description

  The present invention relates to a method for manufacturing a ring-shaped member.

Conventionally, a ring-shaped member 1 as shown in FIG. 9 is obtained by separating a plurality of annular ring-shaped members 1 from a material 2 having a predetermined plate thickness shown in FIGS. It was manufactured by a method of punching in a row or multiple rows.
However, in the conventional manufacturing method, the yield rate, which is the ratio of the weight of the ring-shaped member 1 to the weight of the material 2, is poor, and the cost of the ring-shaped member 1 is increased.
The reason for this is that the ratio of the skeleton S1 and the slug S2 to the ring-shaped member 1 is high. The “skeleton” is a frame-like scrap left by punching a plurality of ring-shaped members 1, and the “slag” is a punch when punching a plurality of ring-shaped members 1. It is a plurality of scraps that are punched and removed at the same time.

  Therefore, a method for forming the ring-shaped member shown in FIGS. 12A and 12B has been proposed (see, for example, Patent Document 1).

  The ring-shaped member forming method described in Patent Document 1 includes a step of continuously bending the width of an oval ring-shaped material into a circular shape while preventing its deformation, and the circular material. And a step of forming a perfect circle.

That is, as shown in FIG. 12 (a), the inner and outer rolls 103 and 104 are movable and freely movable so as to slidably oppose each other on the short diameter side of the oval ring-shaped material 100. A pair of bending rolls 105, and by rotating the inner and outer rolls 103, 104 in the arrow F or the opposite direction, the oval ring-shaped material 100 is fed out in the arrow L or the opposite direction, and a pair of By pushing the bending roll 105 in the direction of the arrow G, a straight portion of the material 100 is sequentially processed by curvature to form a circular material 101.
Next, as shown in FIG. 12B, a large-diameter inner roll 106 is externally fitted to the inner roll 103 so as to be simultaneously rotatable, and is inscribed in a circular material 101. By rotating the inner roll 106 and the outer rolls 103 and 104, the ring-shaped member 102 formed into a perfect circle can be obtained.

  According to such a ring-shaped member forming method, since the circular material 101 is obtained from the elliptical ring-shaped material 100, the ratio of the skeleton and the slug to the perfect circular ring-shaped member 102 will be described with reference to FIG. The ring-shaped member 102 can be made of a material that is lower than the ratio of the skeleton S1 and the slug S2 to the ring-shaped member 1 and the yield rate, which is the ratio of the weight of the ring-shaped member 102 to the weight of the material, is improved. The cost can be reduced.

JP-A-62-203633

  However, in the method for forming the ring-shaped member described in Patent Document 1, the arc-shaped portion 107 having a small radius of curvature remaining in the circular material 101 is moved in the arrow K direction by the large-diameter inner roll 106. It is expanded from the inside by a strong pressing force. In this way, when the arc-shaped portion 107 having a small radius of curvature is expanded from the inside, a large “elongation” occurs in the inner diameter region of the arc-shaped portion 107 having a small radius of curvature, and the meat becomes thin and stress is concentrated. become. For this reason, in the process in which the circular shaped material 101 is formed into the perfect circular ring-shaped member 102, there is a risk that a crack may occur in the inner diameter region of the arc-shaped portion 107, which is in contrast to the elliptical ring-shaped material 100. The yield rate, which is the ratio of the perfect circular ring-shaped member 102, was deteriorated, and the cost was increased.

  The present invention solves such a problem, and an object of the present invention is to improve the yield, which is the ratio of the weight of the ring-shaped member to the weight of the material, and to reduce the cost. In spite of this, it is an object of the present invention to provide a method for manufacturing a ring-shaped member that can improve the yield, which is the ratio of the ring-shaped member to the vertically long annular blank.

The present invention will be described with reference to the reference numerals in FIGS. 3 and 4 for easy understanding of the contents of the invention. A pair of arcuate portions (3d) facing each other at both ends in the longitudinal direction, From a vertically long annular blank (3) having a pair of connecting portions (3b, 3c) which are opposed to each other on both sides in a transverse direction perpendicular to the direction and which connect the ends of the pair of arcuate portions (3d). In the method for manufacturing a ring-shaped member for obtaining a member, the pair of connecting portions (3b, 3c) are expanded outward from the inside of the blank (3), respectively, and the pair of arc-shaped portions (3d) are respectively formed. It is characterized in that it is pressed from the outside toward the inside and expanded to form a ring-shaped member.
According to such a configuration, since the ring-shaped member is obtained from the vertically long annular blank (3), the ratio of the skeleton and the slug relative to the ring-shaped member is reduced as compared with the case shown in FIG. It becomes possible to improve the yield, which is the ratio of the weight of the ring-shaped member to the weight of the material.
Further, the vertically long blank (3) is expanded from the inside of the blank (3) with the pair of connecting portions (3b, 3c) outward, and at the same time, the pair of arc-shaped portions (3d) is also formed. Since each ring is expanded from the outside to the inside and formed into a ring-shaped member, the “elongation” in the inner diameter region of the arc-shaped portion (3d) at both ends in the longitudinal direction of the longitudinal annular blank (3) is suppressed as much as possible. Thus, it is possible to avoid local thinning of the inner diameter region and to relieve stress concentration in the inner diameter region. As a result, cracks can be prevented from occurring in the arc-shaped portions (3d) at both ends in the longitudinal direction of the blank (3), and the yield rate, which is the ratio of the ring-shaped member to the longitudinal annular blank (3), can be improved. it can.

The present invention will be described with reference to the reference numerals attached to FIGS. 3 to 6 for easy understanding of the contents of the invention. A pair of arcuate portions (3d) facing each other at both ends in the longitudinal direction, A ring from a vertically long annular blank (3) having a pair of connecting portions (3b, 3c) that connect the ends of the pair of arcuate portions (3d) opposite to each other on both sides in the lateral direction orthogonal to the vertically long direction. In the method for manufacturing a ring-shaped member for obtaining a ring-shaped member, the pair of connecting portions (3b, 3c) are respectively expanded outward from the inside of the blank (3) to form bulged connecting portions (3B, 3C). At the same time, the pair of arcuate parts (3d) are pressed and expanded from the outside to the inside, respectively, so that the enlarged arcuate part (3D) having a larger radius of curvature than the radius of curvature of the arcuate part (3d). Molding and then expanding the pair of The arc-shaped portion (3D) is pressed and expanded from the outside to the inside to form an expanded arc-shaped portion (3E) having a larger radius of curvature than the radius of curvature of the expanded arc-shaped portion (3D), and While the pair of bulging connection portions (3B, 3C) are restricted from expanding laterally outwardly, the bulging connection portions (3F, 3F) having a curvature radius smaller than the curvature radius of the bulging connection portions (3B, 3C). ) To form a ring-shaped member.
According to such a configuration, since the ring-shaped member is obtained from the vertically long annular blank (3), the ratio of the skeleton and the slug relative to the ring-shaped member is reduced as compared with the case shown in FIG. It becomes possible to improve the yield, which is the ratio of the weight of the ring-shaped member to the weight of the material.
Moreover, when shape | molding a longitudinally long annular blank (3) to a ring-shaped member, first, a pair of connection part (3b, 3c) is expanded outward from the inner side of a blank (3), respectively, and a bulging connection part ( 3B, 3C) and at the same time, the pair of arcuate parts (3d) are expanded from the outside toward the inside to form the enlarged arcuate part (3D). “Elongation” in the inner diameter area of the arc-shaped part (3d) at both ends in the longitudinal direction is suppressed as much as possible, and it is possible to avoid local thinning of the inner diameter area, thereby reducing stress concentration in the inner diameter area. And it can prevent that a crack generate | occur | produces in the circular arc-shaped part (3d) of the longitudinal direction both ends of a blank (3).
Further, the pair of enlarged arcuate portions (3D) are respectively expanded from the outside toward the inside to form an enlarged arcuate portion (3E) having a larger radius of curvature than the radius of curvature of the enlarged arcuate portion (3D). At the same time, the pair of bulging connection portions (3B, 3C) are expanded outwardly in the lateral direction, and the bulging has a smaller radius of curvature than the curvature radius of the bulging connection portions (3B, 3C). Since the ring-shaped member (1) is formed by forming the connecting portions (3F, 3F), the arc-shaped portion (3d) of the vertically long annular blank (3) can be prevented from cracking, and the vertically long annular A yield rate which is a ratio of the ring-shaped member (1) to the blank (3) can be improved.
In particular, the first connecting part (3b, 3c) of the blank (3) is formed into a bulging connection part (3B, 3C) and the arcuate part (3d) is formed into an enlarged arcuate part (3D). And forming the expanded arc-shaped portion (3D) into an expanded arc-shaped portion (3E) having a radius of curvature larger than the radius of curvature, and the bulging connecting portions (3B, 3C) having a curvature smaller than the radius of curvature. Since the ring-shaped member (1) is formed through the second step of forming into the bulging and linking portion (3F, 3F) of the radius, the thick vertically long annular blank (3) is also formed of the arc-shaped portion (3d). It can be formed into a ring-shaped member such as an annular shape or a polygonal shape close to an annular shape while avoiding thinning of the inner diameter region or occurrence of cracks.

  According to the present invention, by taking the material in which the ratio of the skeleton and the slug to the ring-shaped member is kept low, the yield rate which is the ratio of the weight of the ring-shaped member to the weight of the material is improved, and the cost of the ring-shaped member is reduced. Can be planned. Moreover, the “elongation” of the inner diameter region in the arc-shaped portion of the vertically long annular blank is suppressed as much as possible, and it is possible to avoid thinning of the inner diameter region, and stress is not concentrated in the inner diameter region. It is advantageous that cracks do not occur in the arc-shaped portion of the vertically long blank, and the yield, which is the ratio of the ring-shaped member to the vertically long blank, can be improved.

It is a top view which shows 1st Embodiment of the process of punching a blank from a raw material. It is a top view which shows the blank punched out from the raw material of FIG. It is a top view which shows embodiment of the state which set the blank to the 1st stamping apparatus. It is a top view which shows embodiment of the ring-shaped member of the state shape | molded by the 1st embossing apparatus. It is a top view which shows embodiment of the state which set the ring-shaped member to the 2nd die-pressing apparatus. It is a top view which shows embodiment of the ring-shaped part of the state shape | molded by the 2nd die pressing apparatus. It is a top view which shows 2nd Embodiment of a blank. It is a top view which shows other embodiment of the process of punching a blank from a raw material. It is a top view which shows an example of a ring-shaped member. It is a top view which shows 3rd Embodiment of a blank. It is a top view which shows the conventional process of punching a blank from a raw material, (a) shows single row punching, (b) has shown parallel punching. It is explanatory drawing of the shaping | molding method of the ring-shaped member of patent document 1. FIG.

Explanation of symbols

1,1A Ring-shaped member 3,27 Vertical annular blank 3b, 3c Connecting portion 3d Arc-shaped portion 3D, 3E Expanded arc-shaped portion 3B, 3C, 3F Swelling connecting portion

  Hereinafter, preferred embodiments of a method for producing a ring-shaped member according to the present invention will be described with reference to the drawings.

As shown in FIG. 1, while feeding a material 2 having a predetermined plate thickness in the longitudinal direction of the material 2 as indicated by an arrow P, a plurality of vertically-circular annular blanks are spaced by a predetermined interval l in the feeding direction by a pressing device. 3 is punched in series. As the raw material 2, a metal rod such as copper, aluminum, iron, and stainless steel that is formed into a plate by rolling or the like is used, or a plate-shaped material is used from the beginning.
As shown in FIG. 2, the vertically long blank 3 has a vertically long hole 3 a with a small width dimension w <b> 1 inside thereof, and a pair of arcuate portions 3 d and 3 d facing each other at both ends in the vertically long direction, And a pair of linear connecting portions 3b and 3c connecting the ends of the pair of arcuate portions 3d and 3d opposite to each other on both sides in the horizontal direction perpendicular to the direction.

  The vertically long blank 3 is set in the first embossing device 4 as shown in FIG. The first die pressing device 4 includes a pair of left and right moving plates 5, a pair of front and rear molded outer dies 8, and a pair of front and rear guide plates 6. The pair of left and right moving plates 5 is guided by the guide plate 6 and advances and retreats in the left and right directions (arrow X1 and X2 directions) by an advancing and retreating mechanism (not shown). At the tip of each of the left and right moving plates 5, a molding inner mold 7 whose projection plane shape is a back convex arc shape is projected upward, and the left and right molding inner molds 7, 7 are related to a straight line Y orthogonal to the straight line X. The flat front faces of each other are erected at symmetrical positions, and the width dimension w2 of the combined molded inner dies 7 and 7 is such that the vertically long hole 3a of the blank 3 can be fitted into the vertically long hole 3a. It is set to a size slightly smaller than the width dimension w1 of the hole 3a.

The pair of front and rear molded outer dies 8 is guided by the guide plate 6 and advances and retracts in the front-rear direction (arrow Y1, Y2 direction) by an advancing / retreating mechanism (not shown). The front and rear ends of the respective outer molds 8 are each provided with a pressing surface 8a that protrudes vertically upward and whose projection plane shape is recessed in an arc shape. The radius of curvature of the pressing surface 8a is an arc shape in the vertically long annular blank 3 It is set to a value larger than the radius of curvature of the outer peripheral surface of the portion 3d.
The pair of front and rear molded outer dies 8 are arranged on the straight line Y so as to face each other and symmetrically with respect to the straight line X, and the facing interval is vertically long so that a set of vertically long annular blanks 3 can be allowed. It is set to a value larger than the longitudinal dimension of the annular blank 3.

  As shown in FIG. 3, when the vertically long blank 3 is set in the first embossing device 4, the upper die 9 indicated by a two-dot chain line is lowered from above. Accordingly, the upper surfaces of the guide plate 6, the pair of left and right molded inner dies 7, and the pair of front and rear molded outer dies 8 are pressed by the lower surface of the upper mold 9, and the upper surface of the blank 3, the molded inner mold 7, and the molded outer mold 8 are pressed. Is opposed to the lower surface of the upper die 9 through a very small gap (small gap where sliding is allowed) to prevent the blank 3 from warping in the vertical direction.

  In this state, the left and right moving plates 5 are moved outwardly in the lateral direction (in the direction of the arrow X1) perpendicular to the longitudinal direction of the blank 3, and at the same time, the front and rear molding outer dies 8 are respectively inwardly in the longitudinal direction (indicated by the arrow Y1). Direction). Then, the left and right molded inner dies 7 are uniform as shown in FIG. 4 by pressing the connecting portions 3b and 3c on both sides in the left and right lateral direction of the vertically long annular blank 3 from the inside toward the outside (in the direction of the arrow X1). While expanding in the direction of arrow X1 with a large radius of curvature, the front and rear molding outer molds 8 press the arc-shaped portions 3d at both ends in the longitudinal direction of the blank 3 from the outside in the longitudinal direction of the blank 3 to the inside (arrow Y1). It expands with a radius of curvature larger than the radius of curvature of the arcuate portion 3d in FIG. Accordingly, a pair of enlarged arc-shaped portions 3D having a radius of curvature larger than the radius of curvature of the arc-shaped portion 3d in FIG. 3, and a pair of bulging connection portions that continuously bulge and curve in an arc shape with a large radius of curvature. As shown in FIG. 4 having 3B and 3C, an elliptical ring-shaped member 1A is manufactured.

As described above, a plurality of vertically annular blanks 3 are punched from the material 2 shown in FIG. 1, and these vertically annular blanks 3 are formed by the first embossing device 4 to form a ring shape shown in FIG. 4. The member 1A is manufactured. Therefore, the ratio of the skeleton S1 and the slug S2 of FIG. 1 to the ring-shaped member 1A is less than the ratio of the skeleton S1 and the slug S2 to the ring-shaped member 1 described in FIG. The yield, which is the ratio of the weight of the ring-shaped member 1, can be improved, and the cost of the ring-shaped member 1A can be reduced.
Also, when the connecting portions 3b, 3c on both the left and right sides of the vertically long annular blank 3 are pressed from the inside toward the outside in the left and right sides (arrow X1 direction) and expanded in the arrow X1 direction as shown in FIG. At the same time, the blank 3 is pressed from the outside in the longitudinal direction toward the inside (in the direction of the arrow Y1) and expanded with a radius of curvature larger than the radius of curvature of the arcuate portion 3d, so that the circle of the blank 3 The “elongation” of the inner diameter region having a small radius of curvature in the arc-shaped portion 3d is suppressed as much as possible, so that the thinning of the inner diameter region is avoided, but rather the material flow that thickens the arc-shaped portion 3d occurs. Relieve stress concentration in the inner diameter area. As a result, no crack is generated in the arc-shaped portion 3d, and the yield, which is the ratio of the ring-shaped member 1A to the vertically long annular blank 3, can be improved.

  The left and right molding inner molds 7 are further moved in the direction of the arrow X1 from the state of the first mold pressing device 4 shown in FIG. 4 to expand the connecting portions 3b and 3c of the blank 3 from the inside thereof, and the front and rear molding outer molds. By moving 8 in the direction of the arrow Y1 and expanding the arc-shaped portion 3d of the blank 3, it can be formed into a more annular shape than the ring-shaped member 1A shown in FIG.

  When the vertically long annular blank 3 is thick or when the ring-shaped member 1A shown in FIG. 4 is more reliably formed into a shape close to an annular shape, the second mold shown in FIG. Set in the pusher 11.

  The second mold pressing device 11 includes a pair of front and rear molding outer molds 12 and a pair of left and right regulation molds 13. The molded outer die 12 is guided by the guide plate 14 and advanced and retracted in the front-rear direction (in the directions of arrows Y1 and Y2) by an unillustrated advance / retreat mechanism, and the restriction die 13 is guided by the guide plate 14 and is not shown. To move forward and backward in the left-right direction (arrow X1, X2 direction).

  The pair of front and rear molded outer dies 12 includes a mounting surface 12a and a pressing surface 12b that protrudes vertically upward from the mounting surface 12a and whose projection plane shape is recessed in an arc shape. The radius of curvature of the pressing surface 12b Is set to a value larger than the radius of curvature of the outer peripheral surface of the enlarged arc-shaped portion 3D in the ring-shaped member 1A shown in FIG. 4, and the annular ring-shaped member approximated to the annular shape shown in FIG. 1 is formed on an arcuate pressing surface 12b that extends along a part of the outer peripheral surface. In addition, the pair of left and right restricting dies 13 are provided with a restricting surface 13a whose projection plane shape is recessed in an arc shape on the end surface facing the other party, and the radius of curvature of the restricting surface 13a is a ring shape shown in FIG. 6 is set to a value smaller than the radius of curvature of the outer peripheral surface of the bulging connection portions 3B and 3C in the member 1A, and a part of the outer peripheral surface of the annular ring member 1 approximated to the annular shape shown in FIG. Is formed on the arc-shaped pressing surface 12b.

  As shown in FIG. 5, the bulging and linking portions 3B and 3C in the ring-shaped member 1A are sandwiched between the left and right regulating dies 13, and the enlarged arc-shaped portion 3D and the vicinity thereof in the ring-shaped member 1 are mounted on the molded outer die 12. When the ring-shaped member 1A is set on the second die pressing device 11 in a state of being placed on the placement surface 12a, the upper die 15 indicated by a two-dot chain line is lowered from above. Thereby, the upper surfaces of the ring-shaped member 1A, the molded outer mold 12 and the regulation mold 13 are opposed to the lower surface of the upper mold 15 via a very small gap (small gap where sliding is allowed), The ring-shaped member 1A is prevented from warping in the vertical direction.

  In this state, the outer mold 12 is moved in the arrow Y1 direction. Then, the pressing surface 12b of the molded outer mold 12 presses the enlarged arc-shaped portion 3D of the ring-shaped member 1A from the outside toward the inside, and expands with a large radius of curvature. Thereby, both the enlarged arc-shaped portions 3D of the ring-shaped member 1A are pressed against the pressing surface 12b by pressing the outer surface of the diameter inward from the outer side by the pressing surface 12b recessed in the arc shape of the molded outer mold 12. As shown in FIG. 6, an expanded arc-shaped portion 3E having a radius of curvature larger than the radius of curvature of the expanded arc-shaped portion 3D is formed, and “elongation” is formed in the outer diameter area of the expanded arc-shaped portion 3E. As a result, the “elongation” of the inner diameter region is suppressed as much as possible, and it is possible not only to avoid the thinning of the inner diameter region, but rather, the material flow that thickens the enlarged arc-shaped portion 3E occurs. Thus, the stress concentration in the inner diameter region is alleviated and no cracks are generated in both enlarged arc-shaped portions 3E.

  Further, at the same time when both the enlarged arc-shaped portions 3E are formed, the bulging connection portions 3B and 3C in the ring-shaped member 1A shown in FIG. 5 are expanded in the direction of the arrow X1, but at this time, the bulging connection portion 3B. , 3C is deformed so that the ring-shaped member 1A extends along the restricting surface 13a while being restricted from excessively expanding in the direction of the arrow X1 by contacting the restricting surface 13a of the restricting die 13 which is recessed in an arc shape. As a result, arc-shaped bulging connection portions 3F and 3F having a radius of curvature smaller than the curvature radius of the bulging connection portions 3B and 3C in the ring-shaped member 1A shown in FIG. An annular ring-shaped member 1 as shown in FIG. 6 and FIG. 9 in which the bulging and connecting portion 3F is continuous is manufactured.

  When the annular ring-shaped member 1 is molded in this way, the “elongation” in the inner diameter region of the enlarged arc-shaped portion 3D and the bulging connection portions 3B and 3C is suppressed as much as possible, and the inner diameter region becomes thin. Is avoided, and stress concentration in the inner diameter area is relieved. As a result, since the ring-shaped member 1 can be manufactured without causing cracks in the enlarged arc-shaped portion 3D and the bulging connection portions 3B, 3C, the yield is the ratio of the ring-shaped member 1 to the vertically long annular blank 3 The rate can be improved.

  In the above embodiment, as shown in FIG. 2, the vertically long annular blank 3 having a small width dimension w <b> 1 of the vertically long hole 3 a is punched out, and this blank 3 is manufactured as a ring-shaped member, but as shown in FIG. 7. A vertical annular blank 27 having an oblong vertical hole 27a whose width dimension w3 is sufficiently larger than the width dimension w1 in FIG. 2 is punched out, and this blank 27 is formed into a ring-shaped member in the same procedure as in the above embodiment. You can also. Even in this case, similarly to the above-described embodiment, it is possible to improve the yield, which is the ratio of the ring-shaped member to the vertically long annular blank 27, and to reduce the cost of the ring-shaped member.

  Further, when punching a plurality of vertically-circular annular blanks 3 and 27 from the material 2 having a predetermined width, as shown in FIGS. A pair of linear connecting portions 3b, 3c in the annular blanks 3, 27 are formed on the outer end surfaces, and the pair of linear connecting portions 3b, 3c are connected to each other by shearing the material 2 by a pressing device. Arc-shaped portions 3d can be formed at both ends in the longitudinal direction. According to this, it is possible to take the material with the scrap ratio with respect to the vertically long blanks 3 and 27 being minimized. That is, the scrap is punched and removed with a punch when punching the vertically long hole 3a or the oblong vertically long hole 27a, and the longitudinal direction as shown by diagonal lines in FIGS. 8 (a) and 8 (b). And the drum-shaped end plate 2x existing between the vertically long annular blanks 3 or the blanks 27 which are separated from the material 2. As a result, the yield, which is the ratio of the weight of the ring-shaped member 1 to the weight of the material 2, can be further improved.

  In the vertically long annular blanks 3 and 27, the connecting portions 3b and 3c that connect the ends of the pair of arc-shaped portions 3d and 3d are not limited to those formed in a straight line as shown in FIG. 2, but for example, as shown in FIG. It may be formed in a non-linear shape consisting of a bent line. In addition, instead of being obtained by punching the plate-like material 2 as shown in FIG. 1, the vertically long annular blanks 3 and 27 may be obtained by pressing, forging, or the like such as cutting and punching a metal bar. it can.

Claims (2)

  A vertically long ring having a pair of arc-shaped portions facing each other at both ends in the longitudinal direction and a pair of connecting portions facing each other on both sides in the transverse direction perpendicular to the longitudinal direction and connecting the ends of the pair of arc-shaped portions. In the manufacturing method of the ring-shaped member for obtaining the ring-shaped member from the blank, the pair of connecting portions are respectively expanded outward from the inside of the blank, and the pair of arc-shaped portions are respectively directed from the outside to the inside. A method for producing a ring-shaped member, wherein the ring-shaped member is formed by pressing and expanding.   A vertically long ring having a pair of arc-shaped portions facing each other at both ends in the longitudinal direction and a pair of connecting portions facing each other on both sides in the transverse direction perpendicular to the longitudinal direction and connecting the ends of the pair of arc-shaped portions. In the manufacturing method of the ring-shaped member which obtains the ring-shaped member from the blank, the pair of connecting portions are expanded outward from the inside of the blank to form the bulging connecting portions, and the pair of arc-shaped portions Are pressed from the outside to the inside to be expanded to form an enlarged arc-shaped portion having a radius of curvature larger than the radius of curvature of the arc-shaped portion, and then the pair of enlarged arc-shaped portions are respectively set from the outside to the inside. While pressing toward the expanded arc-shaped portion having a radius of curvature larger than the radius of curvature of the expanded arc-shaped portion, the pair of bulging connection portions are controlled to expand outward in the lateral direction. Method of manufacturing a ring-shaped member, characterized in that go by molding the bulging linking portions of smaller radius of curvature than the serial bulging linking portions forming a ring-shaped member.

Images