JP5392053B2 - Manufacturing method of laminated ring - Google Patents

Description

  The present invention relates to a method of manufacturing a laminated ring used for a transmission belt of a belt type continuously variable transmission for a vehicle, and in particular, to increase the durability of a band-shaped metal member constituting the laminated ring, at both ends in the width direction thereof. The present invention relates to a technique for imparting residual compressive stress.

  A multi-layer ring used for a transmission belt of a vehicular belt type continuously variable transmission for supporting a plurality of elements connected in a ring is known. Yes. This laminated ring is manufactured as follows, for example. First, a strip steel such as maraging steel or stainless steel is welded at both ends to form a cylindrical member. Next, the cylindrical member is divided at predetermined intervals in the axial direction to form a plurality of short cylindrical members. Next, the plurality of short cylindrical members are rolled in the thickness direction and the perimeters are adjusted to form a plurality of endless annular band-like metal members having different perimeters. Subsequently, surface treatment such as nitriding treatment or shot peening is performed on them, and an aging treatment is performed thereon, so that, for example, hardness and fatigue strength are improved. Next, a plurality of layers are stacked in close contact with each other to form a stacked ring. As a manufacturing method of such a laminated ring, for example, a manufacturing method described in Patent Document 1 is known.

  Patent Document 1 describes a circumference correction device used for adjusting the circumference. This circumferential length correction device surrounds the belt-shaped metal member by locally pressing a part of the circumferential direction of the rotating roller and the driven roller and the belt-shaped metal member wound around them from the inner circumferential side toward the outer circumferential side. And a straightening roller extending in the direction. By using this circumference correction device, the belt-like metal member is given a circular arc shape that is convex on the outer circumference side in the cross section in the width direction, and is given a residual stress in the circumferential direction. By providing the arc shape, when a plurality of band-shaped metal members are stacked on each other, the stacked state is easily maintained. In addition, during use of the transmission belt, the belt-like metal belt generates different stresses on the inner peripheral side and the outer peripheral side, but the stress difference between the inner peripheral side and the outer peripheral side at this time is canceled out. By preliminarily applying the circumferential residual stress to the band-shaped metal member, early fatigue of the band-shaped metal member due to the stress difference between the inner peripheral side and the outer peripheral side can be suppressed.

JP 2009-22991 A

  By the way, it is thought that durability of a lamination | stacking ring falls because the both ends of the width direction are fatigued by the use. In order to suppress this decrease in durability, the conventional method for manufacturing a laminated ring is to apply a residual compressive stress to the entire surface of the band-shaped metal member by performing a surface treatment such as nitriding or shot peening. A surface treatment process for increasing fatigue strength is included. In addition, for example, it is conceivable to reduce the stress generated per one of the band-shaped metal members by increasing the number of the plurality of band-shaped metal members constituting the laminated ring.

  However, the apparatus for performing the surface treatment is large-scale, and there is a problem that the manufacturing cost increases because the cost of parts increases when the number of strip-shaped metal members is increased. Further, in order to suppress the deterioration of the durability, it is only necessary to apply residual compressive stress to both end portions in the width direction of the band-shaped metal member to increase the fatigue strength at both ends. Residual compressive stress was applied to the surface.

  The present invention has been made against the background of the above circumstances, and the object of the present invention is to form a width direction of the band-shaped metal member so that circumferential compressive stresses are generated at both ends in the width direction of the band-shaped metal member. An object of the present invention is to provide a method for manufacturing a laminated ring that can increase the durability of a band-shaped metal member by providing a residual stress distribution.

To achieve this object, the gist of the invention according to claim 1 is that: (a) a plurality of endless annular belt-like metal members are stacked in close contact, and support a plurality of elements connected in an annular shape; A manufacturing method of a laminated ring used for a transmission belt of a belt type continuously variable transmission for a vehicle, wherein (b) the band-shaped metal formed in an arc shape whose cross section in the width direction is convex on the outer peripheral side Residual stress that applies circumferential residual compressive stress to both ends in the width direction of the band-shaped metal member by subjecting the member to a process in which the outer peripheral side of the central portion in the width direction is partially extended in the width direction. look including the application step, the residual stress applying step, the (c-1) and at least one pair of support rollers said belt-shaped metal member provided rotatably about the axis is wound, respectively, (c-2) Center axis parallel to the axis of the support roller A first roller die provided on the inner peripheral side of the belt-like metal member so as to be rotatable, and (c-3) having a smaller diameter than the first roller die and parallel to the axis of the first roller die The belt-shaped metal member is provided on the opposite side to the first roller die so as to be rotatable around a central axis, and a central portion in the width direction of the belt-shaped metal member is between the first roller die and the thickness direction. Using a residual stress applying device comprising: a second roller die that partially extends in the width direction of the outer peripheral side of the central portion in the width direction of the band-shaped metal member by rotating while narrowly compressing to (d) (E) the outer peripheral surfaces of the first roller die and the second roller die that are in contact with the band metal member are each provided with an axis thereof. In the cross section passing through the heart (F) a radius of curvature in a cross section passing through the axis of the outer peripheral surface of the second roller die abutting on the band-shaped metal member corresponds to the band-shaped metal member of the first roller die. (G) the radius of curvature in the cross section passing through the axis of the outer peripheral surface contacting the belt-shaped metal member of the second roller die is set to be smaller than the radius of curvature in the cross section passing through the axis of the outer peripheral surface in contact with That is, it is set to be smaller than half of the outer diameter of the second roller die .

According to the method for manufacturing a laminated ring of the invention according to claim 1, the outer peripheral side of the central portion in the width direction is partially formed with respect to the band-shaped metal member formed in an arc shape in which the cross section in the width direction is convex on the outer peripheral side. In particular, since a process of extending in the width direction includes a residual stress applying step for applying a residual compressive stress in the circumferential direction to both ends in the width direction of the band-shaped metal member, It is possible to enhance the durability of the band-shaped metal member by imparting a residual stress distribution in the width direction to the band-shaped metal member so that circumferential compressive stress is generated at both ends. Further, the residual stress applying device used in the residual stress applying step includes a first roller die provided on an inner peripheral side of the band-shaped metal member wound around a plurality of support rollers, and the first roller die. The outer peripheral side of the central portion in the width direction of the band-shaped metal member is partially rotated by narrowing the central portion in the width direction of the band-shaped metal member in the thickness direction between the first roller dies. Therefore, as the second roller die has a smaller diameter than the first roller die, the outer peripheral side of the central portion in the width direction of the band-shaped metal member is compared with the inner peripheral side. Since both end portions in the width direction of the band-shaped metal member are relatively moved toward the inner peripheral side with respect to the central portion and compressed in the circumferential direction, the first roller die and the second roller die are extended in the width direction. On the outside diameter Flip residual compressive stress at both ends in the width direction of the belt-shaped metal member can be imparted. Further, the outer peripheral surfaces of the first roller die and the second roller die, which are in contact with the band-shaped metal member, are respectively formed in an arc shape having a convex shape on the outer peripheral side in a cross section passing through the axial center thereof, and the second roller die The radius of curvature in the cross section passing through the axis of the outer peripheral surface abutting on the belt-shaped metal member is smaller than the radius of curvature in the cross section passing through the axis of the outer peripheral surface of the first roller die in contact with the belt-shaped metal member. Since the radius of curvature in the cross section passing through the axis of the outer peripheral surface of the second roller die that contacts the belt-shaped metal member is set to be smaller than half of the outer diameter of the second roller die, Since the material fluidity in the width direction when the outer peripheral side of the central portion of the band-shaped metal member is extended in the width direction by the second roller die is improved, both the band-shaped metal members are preferably used. Parts are compressed so as to be relatively moved toward the inner periphery side in the circumferential direction with respect to the respective central portion.

It is a perspective view which shows a part of the circumferential direction of the transmission belt of the belt type continuously variable transmission for vehicles which concerns on this invention. It is sectional drawing which shows notionally the cross section of the width direction about the strip | belt-shaped metal member of the innermost circumference among the some strip | belt-shaped metal members which comprise the lamination | stacking ring of FIG. It is process drawing for demonstrating the manufacturing process of the lamination | stacking ring of FIG. It is a conceptual diagram which shows the principal part of the residual stress provision apparatus used in the residual stress provision process of FIG. It is sectional drawing which shows the VV arrow part cross section of the residual stress provision apparatus of FIG. It is a figure which shows a mode that the distance from the curvature-radius center of the end of the width direction of the strip | belt-shaped metal member of FIG. 1 arrange | positioned at perfect circle shape, ie, a curvature radius, changes before and after the residual stress provision process of FIG.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily drawn accurately.

  FIG. 1 is a perspective view showing a part in the circumferential direction of a transmission belt 10 of a belt type continuously variable transmission for a vehicle according to the present invention. In FIG. 1, the transmission belt 10 includes a first laminated ring 14 and a second laminated ring 16 (hereinafter referred to as a plurality of endless annular belt-like metal members 12, which are laminated in close contact with each other. (If not particularly distinguished, it is described as a laminated ring 14 (16)) and a plate-like metal connected in an annular shape in the thickness direction along the first laminated ring 14 and the second laminated ring 16 respectively. And a plurality of elements 18. The element 18 includes a pair of concave grooves 20 that are recessed toward the center on both side portions in the width direction. The first laminated ring 14 and the second laminated ring 16 are formed on one and the other concave portions of the plurality of elements 18. Each is inserted into the groove 20. The laminated ring 14 (16) is used to support a plurality of elements 18. The laminated ring 14 (16) is formed, for example, by laminating nine strip-shaped metal members 12 that are adjusted so that the circumferential length increases in order from the inner circumferential side to the outer circumferential side, in order from the inner circumferential side. In FIG. 1, for convenience, the laminated ring 14 (16) composed of the nine layers of the band-shaped metal member 12 is not necessarily illustrated in nine layers.

  FIG. 2 is a cross-sectional view conceptually showing a cross section in the width direction of the innermost band-shaped metal member 12 among the plurality of band-shaped metal members 12 constituting the laminated ring 14 (16). In FIG. 2, the band-shaped metal member 12 is formed in an arc shape in which the cross section in the width direction is convex on the outer peripheral side. Residual tensile stress is applied to the strip-shaped metal member 12 on the outer peripheral side of the central portion 22 in the width direction, and residual compressive stress is applied to the other end portions 24 on the inner peripheral side of the central portion 22 and in the width direction. Has been granted. In other words, a residual stress distribution is given to the band-shaped metal member 12 in the width direction. In FIG. 2, a residual tensile stress region A1 indicates a region where the residual tensile stress is applied, and a residual compressive stress region A2 indicates a region where the residual compressive stress is applied.

In the cross section shown in the width direction of the cross-section i.e. Figure 2 of the belt-shaped metal member 12, the curvature radius R _R of the inner peripheral surface 26 of the belt-shaped metal member 12, the inner peripheral surface thereof and positioned on the inner peripheral side of the inner circumferential surface 26 thereof It is set to be larger than 26 and the curvature radius R _E of the one side 28 of the groove 20 of the engageable elements 18. For this reason, even if the band-shaped metal member 12 contacts the one side surface 28 in the thickness direction, for example, the end 24 of the band-shaped metal member 12 is deformed so as to move relative to the central portion 22 toward the outer peripheral side. It is suppressed that the residual compressive stress of the edge part 24 falls because the edge part 24 is pulled in the circumferential direction.

  FIG. 3 is a process diagram for explaining a manufacturing process of the laminated ring 14 (16) shown in FIG. Hereinafter, the manufacturing method of the laminated ring 14 (16) will be described with reference to the process diagram of FIG.

  In FIG. 3, first, in a steel strip cutting process P <b> 1, a steel strip 30 such as maraging steel or stainless steel is cut into a predetermined length by cutting into a predetermined length.

  Next, in the welding step P2, one and the other cut surfaces of the cut flat plate 32 are welded together to form the cylindrical member 34.

  Next, in the first solution heat treatment step P3, in order to homogenize the hardness of the cylindrical member 34 in which the vicinity of the welded portion is partially hardened by the heat at the time of welding in the welding step P2, the first cylindrical member 34 is subjected to the first solution. The solution treatment of is performed.

  Next, in the cylindrical member cutting step P4, the cylindrical member 34 having the homogenized hardness is cut in a direction perpendicular to the axial center for each predetermined length in the axial direction, so that a plurality of short cylindrical members 36 are obtained. It is formed.

  Next, in the barrel polishing step P5, all or a part of the short cylindrical member 36 is put together with an abrasive in a predetermined container that is sequentially rotated or vibrated and polished.

  Next, in the rolling process P6, the polished short cylindrical member 36 is rolled to a predetermined thickness to form an annular member 38.

  Next, in the second solution treatment step P7, in order to restore the metal structure of the annular member 38 deformed by rolling in the rolling step P6, the annular member 38 is subjected to a second solution treatment. The

  Next, in the circumference adjusting step P8, the annular member 38 subjected to the second solution treatment is adjusted to a predetermined circumference. Specifically, for example, the annular member 28 is provided on the inner peripheral side of the band-shaped metal member 12 while being wound around a pair of rotating rollers (not shown) arranged in parallel with each other and rotated in the circumferential direction. By being pressed from the inner peripheral side toward the outer peripheral side by a correction roller (not shown), it is adjusted to a predetermined peripheral length. The outer peripheral surfaces of the rotating roller and the correction roller are formed in a circular arc shape having a convex shape on the outer peripheral side in a cross section passing through an axis parallel to the width direction of the band-shaped metal member 12. The band-shaped metal member 12 is formed in an arc shape in which the cross section in the width direction is convex on the outer peripheral side by transferring the arc shape of the outer peripheral surface when adjusting the circumference.

  Next, in the residual stress applying step P9, the circumferential residual compressive stress is applied to both end portions 24 in the width direction of the band-shaped metal member 12 whose peripheral length is adjusted.

  Next, in the aging treatment step P10, an aging treatment is performed on the band-shaped metal member 12 to which the residual compressive stress is applied. This aging treatment is performed so that the residual compressive stress applied in the residual stress applying step P9 is not released.

  Next, in the stacking step P11, the nine strip-shaped metal members 12 having different peripheral lengths subjected to the aging treatment are stacked in close contact with each other so that the peripheral length sequentially increases from the inner peripheral side toward the outer peripheral side, A laminated ring 14 (16) is formed.

  Hereinafter, the residual stress applying step P9 will be described in more detail. FIG. 4 is a conceptual diagram showing a main part of the residual stress applying device 40 used in the residual stress applying step P9. In FIG. 4, the residual stress applying device 40 includes two pairs of support rollers 42 that are rotatably provided around axes C <b> 1 to C <b> 4 that are parallel to each other and around which the band-shaped metal member 12 is wound, and shafts of the support rollers 42. A first roller die 44 provided on the inner peripheral side of the band-shaped metal member 12 so as to be rotatable around an axis C5 parallel to the centers C1 to C4, that is, parallel to the width direction of the band-shaped metal member 12, and the first roller die 44 The radius R2 is smaller than the radius R1 of the first roller die 44, and is rotatable about an axis C6 parallel to the axis C5 of the first roller die 44. A central portion 22 of the band-shaped metal member 12 is provided as shown in FIG. 5 to be described later in a state where a part of the band-shaped metal member 12 in the circumferential direction is convex toward the inner peripheral side when viewed in the width direction of the band-shaped metal member 12. 1st roller A second roller die 46 is provided that partially extends in the width direction on the outer peripheral side of the central portion 22 of the band-shaped metal member 12 by rotating while being narrowly pressed in the thickness direction with the die 44.

FIG. 5 is a cross-sectional view showing a VV arrow section of the residual stress applying device 40 of FIG. As shown in FIG. 5, the outer peripheral surfaces 48 and 50 of the first roller die 44 and the second roller die 46 that are in contact with the band-shaped metal member 12 are shown in cross sections passing through the axes C5 and C6 shown in FIG. The cross section has a predetermined radius of curvature R3 and R4 and is formed in a circular arc shape that is convex on the outer peripheral side. The radius of curvature R3 is smaller than the radius of curvature R _R of the inner peripheral surface 26 of the belt-shaped metal member 12 after the residual stress shown by the solid line granted in FIG. The radius of curvature R4 is set to be smaller than the radius R2 that is half of the outer diameter of the second roller die 46.

  In the residual stress applying step P9, the residual stress applying device 40 is used to apply the residual compressive stress to both end portions 24 in the width direction of the band-shaped metal member 12. Specifically, the outer peripheral side of the central portion 22 in the width direction of the band-shaped metal member 12 is partially extended in the width direction by the second roller die 46 over the entire circumference, so that the state shown by the dotted line in FIG. Both end portions 24 in the width direction of the band-shaped metal member 12 are moved relative to the inner peripheral side with respect to the central portion 22 over the entire circumference, and a state indicated by a solid line in FIG. 5 is obtained. FIG. 6 is a diagram illustrating a state in which the distance from the center of the radius of curvature of one end in the width direction of the strip-shaped metal member 12 arranged in a perfect circle shape, that is, the radius of curvature Re, changes before and after the residual stress applying step P9. As shown in FIG. 6, the radius of curvature Re decreases from the radius of curvature Re1 before the residual stress applying step P9 shown by the dotted line to the radius of curvature Re2 after the residual stress applying step P9 shown by the solid line. Therefore, the circumferential length L at both ends of the strip-shaped metal member 12 is reduced from the circumferential length L1 (= 2 × Re1 × π) to the circumferential length L2 (= 2 × Re2 × π). Along with this, the inner peripheral sides of both end portions 24 and the central portion 22 of the band-shaped metal member 12 are compressed in the circumferential direction, and a residual compressive stress region A1 is formed by applying a circumferential compressive stress to them. The applied residual compressive stress increases toward the end portion 24 side where the amount of relative movement to the inner peripheral side with respect to the central portion 22 is large before and after the residual stress applying step P9.

  In the residual stress applying device 40, the amount by which the outer peripheral side of the central portion 22 extends in the width direction relative to the inner peripheral side is such that the radius R2 of the second roller die 46 is the radius R1 of the first roller die 44. The smaller the size, the larger the size. Further, the amount by which the both end portions 24 are moved relative to the inner peripheral side with respect to the central portion 22 and the residual compressive stress applied to the both end portions 24 are relative to the outer peripheral side of the central portion 22 relative to the inner peripheral side. In particular, the larger the amount extended in the width direction, the larger. The radius R2 of the second roller die 46 and the radius R1 of the first roller die 44 of this embodiment are experimentally determined and set in advance according to the residual compressive stress to be applied to the both end portions 24.

  Returning to FIG. 5, the thickness t of the band-shaped metal member 12 is the residual stress indicated by the solid line from the thickness dimension t1 before the residual stress applying step P9 indicated by the dotted line because the outer peripheral side of the central portion 22 extends in the width direction. It becomes smaller (thinner) to the thickness dimension t2 after the application step P9. The outer peripheral surface 52 of the central portion 22 is flatter than the inner peripheral surface 26.

  As described above, according to the manufacturing method of the laminated ring 14 (16) of the present embodiment, the widthwise cross section of the band-shaped metal member 12 formed in an arc shape having a convex shape on the outer peripheral side is formed in the width direction. Residual stress application step P9 for applying a residual compressive stress in the circumferential direction to both end portions 24 in the width direction of the band-shaped metal member 12 by partially extending the outer peripheral side of the central portion 22 in the width direction. Therefore, the band-shaped metal member 12 is provided with a residual stress distribution in the width direction so that circumferential compressive stress is generated at both end portions 24 in the width direction of the band-shaped metal member 12. Can be increased.

  Moreover, according to the manufacturing method of the laminated ring 14 (16) of the present embodiment, the residual stress applying device 40 used in the residual stress applying step P9 includes the band-shaped metal member 12 wound around the plurality of support rollers 42. A first roller die 44 provided on the peripheral side and a diameter smaller than that of the first roller die 44, and a central portion 22 in the width direction of the band-shaped metal member 12 is formed in the thickness direction between the first roller die 44 and the first roller die 44. The second roller die 46 has a smaller diameter than the first roller die 44 because the second roller die 46 includes a second roller die 46 that partially extends the outer peripheral side of the central portion 22 in the width direction by rotating while narrowing pressure. The outer peripheral side of the central portion 22 in the width direction of the band-shaped metal member 12 is extended in the width direction as compared with the inner peripheral side, and both end portions 24 in the width direction of the band-shaped metal member 12 are inner peripheral with respect to the central portion 22. Phase to side Since it is moved and compressed in the circumferential direction, residual compressive stress is applied to both ends 24 in the width direction of the band-shaped metal member 12 according to the outer diameter R1 of the first roller die 44 and the outer diameter R2 of the second roller die 46. can do.

  Moreover, according to the manufacturing method of the lamination | stacking ring 14 (16) of a present Example, the outer peripheral surface 50 contact | abutted to the inner peripheral surface 26 of the strip | belt-shaped metal member 12 of the 2nd roller die 46 is in the cross section which passes along the axial center C6. It has a predetermined radius of curvature R4 and is formed in an arc shape that is convex on the outer peripheral side, and the predetermined radius of curvature R4 is set to be smaller than half the outer diameter of the second roller die 46, that is, the radius R2. Therefore, when the outer peripheral side of the central portion 22 of the band-shaped metal member 12 is extended in the width direction by the second roller die 46, the material fluidity in the width direction is enhanced, and therefore the both end portions 24 of the band-shaped metal member 12 are preferably used. Are respectively moved to the inner peripheral side with respect to the central portion 22 and compressed in the circumferential direction.

  As mentioned above, although one Example of this invention was described in detail with reference to drawings, this invention is not limited to this Example, It can implement in another aspect.

  For example, in the above-described embodiment, the band-shaped metal member 12 is formed from maraging steel or stainless steel, but may be formed from other steel materials.

  In addition, the mechanical configuration of the residual stress applying device 40 for rotating the belt-shaped metal member 12 in the annular state in the circumferential direction in the residual stress applying step P9 of the above-described embodiment is an example, and other This is realized even with a known mechanical configuration.

Further, although in the foregoing embodiments, the radius of curvature R3 of the outer peripheral surface 48 of the first roller die 44, than the radius of curvature R _R of the inner peripheral surface 26 of the belt-shaped metal member 12 after the residual stress shown by the solid line granted 5 Although it was set small, for example, it may be _larger than the curvature radius RR.

  Further, the first roller die 44 does not necessarily have an arc shape that is convex on the outer peripheral side in a cross section passing through the axis C5. For example, it may be formed in a cylindrical surface shape.

  Further, the band-shaped metal member 12 may be further subjected to a surface treatment such as a nitriding treatment.

  It should be noted that the above description is merely an embodiment, and other examples are not illustrated. However, the present invention is implemented in variously modified and improved modes based on the knowledge of those skilled in the art without departing from the gist of the present invention. Can do.

10: Transmission belt 12: Band-shaped metal member 18: Element 22: Central portion 24: End portion 40: Residual stress applying device 42: Support roller 44: First roller die 46: Second roller die 50: Outer peripheral surface P9: Residual stress Applying steps C1 to C4: shaft center (support roller shaft center)
C5: Axis (axis of the first roller die)
C6: Axis (Axis of the second roller die)
R2: Radius (half the outer diameter of the second roller die)
R4: radius of curvature

Claims (1)

A method of manufacturing a laminated ring, which is formed by laminating a plurality of endless annular band-shaped metal members in close contact with each other and used for a transmission belt of a belt type continuously variable transmission for a vehicle to support a plurality of elements linked in an annular shape. There,
The belt-like metal member formed in an arc shape whose cross section in the width direction has a convex shape on the outer peripheral side is subjected to a process of partially extending the outer peripheral side of the central portion in the width direction in the width direction, thereby forming the belt-like shape. the residual stress applying step respectively imparting a circumferential residual compressive stress at both ends in the width direction of the metal member seen including,
The residual stress applying step includes
At least a pair of support rollers, each of which is rotatably provided around an axis and on which the belt-shaped metal member is wound;
A first roller die provided on the inner peripheral side of the band-shaped metal member so as to be rotatable about an axis parallel to the axis of the support roller;
A diameter smaller than that of the first roller die and provided on the opposite side to the first roller die with respect to the band-shaped metal member so as to be rotatable around an axis parallel to the axis of the first roller die; By rotating the central portion in the width direction of the band-shaped metal member while narrowly pressing in the thickness direction between the first roller dies, the outer peripheral side of the central portion in the width direction of the band-shaped metal member is partially expanded to the width. A second roller die extending in the direction
The residual compressive stress is provided to both ends in the width direction of the band-shaped metal member using a residual stress applying device.
The outer peripheral surfaces of the first roller die and the second roller die that are in contact with the band-shaped metal member are each formed in a circular arc shape that is convex on the outer peripheral side in a cross section passing through the axis.
The radius of curvature in the cross section passing through the axial center of the outer peripheral surface of the second roller die that contacts the band-shaped metal member is in the cross section passing through the axial center of the outer peripheral surface of the first roller die that contacts the band-shaped metal member. Set smaller than the radius of curvature,
A radius of curvature in a cross section passing through the axis of the outer peripheral surface of the second roller die contacting the band-shaped metal member is set to be smaller than half of the outer diameter of the second roller die. Ring manufacturing method.

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