Abstract: A die includes a stationary die, a movable die, which is opposed to the stationary die and reciprocatable in a first direction to change a distance between the stationary and movable dies, and a transfer mechanism, which transfers a workpiece, upon which plastic deformation work is performed between the stationary and movable dies, in a second direction crossing the first direction.

Abstract: An annular groove portion is formed between portions corresponding to groove portions and thereafter the groove portions are formed while the annular groove is pressed. Consequently, since the stress produced due to a plastic deformation in forming the groove portions can be absorbed by the annular groove having a smaller rigidity than the groove portions, no undesirable plastic deformation of the groove portions occurs and hence the accuracy of the finished size of the multi-stage pulley can be improved. Furthermore, the capital investment in groove forming rollers can be reduced and the manufacturing cost of the multi-stage pulley can be reduced.

Abstract: The manufacturing cost of a multi-stage pulley is reduced without coaxially arranging a plurality of groove forming sections. While a portion between groove sections 103 is being pushed by a pushing roller 204, the groove sections 103 are successively formed. While a portion of workpiece W2 pushed by a groove forming roller 206 to form one groove section 103a and a portion of workpiece W2 pushed by a groove forming roller 207 to form the other groove section 103b are being shifted from each other in the circumferential direction, one groove section (103a) and the other groove section (103b) are simultaneously formed. Due to the foregoing, when the groove sections 103 are formed, it is possible to prevent the deformation of the groove section 103 and the groove section 103 which is adjacent to it. Accordingly, it is possible to enhance the yield of the multi-stage pulley 100 without coaxially arranging a plurality of groove forming sections.

Abstract: An annular groove portion is formed between portions corresponding to groove portions and thereafter the groove portions are formed while the annular groove is pressed. Consequently, since the stress produced due to a plastic deformation in forming the groove portions can be absorbed by the annular groove having a smaller rigidity than the groove portions, no undesirable plastic deformation of the groove portions occurs and hence the accuracy of the finished size of the multi-stage pulley can be improved. Furthermore, the capital investment in groove forming rollers can be reduced and the manufacturing cost of the multi-stage pulley can be reduced.

Abstract: A multi-stepped pulley, and a method and apparatus for manufacturing the same, wherein the mechanical strength is increased while keeping down an increase of mass and a rise of manufacturing costs by pressing against portions of a surface of a hollow metal material having a circular cross-section corresponding to a connection portion of a plurality of pulleys by pressing rollers and simultaneously crushing the material in an axial direction so as to integrally form first and second rims, first and second webs, and a connection portion thereof.

Abstract: According to the present invention, a brake unit is disposed at a side of the forward direction of the fin material from a reforming unit. The brake unit contracts the fin material so that the adjacent folded portions contact with each other while being reformed. Thus, the contracted fin material is in a stable state not to be deformed easily. In this way, even if moment tilting flat portions of corrugated fin is given by the reforming unit, the flat portions are prevented from tilting. A concave or convex deformation of the folded portions can be reformed satisfactorily.

Abstract: To produce a corrugated fin suitably used to fabricate heat exchangers such as radiators, condensers of the air conditioners, etc., for automobiles, a toothed roller for forming a corrugated fin has circumferential teeth comprising a tooth tip having a concavity, a tooth bottom having a convexity, and a tooth slope having a louver cutting edge between the tooth tip and the tooth bottom, wherein a top of the convexity of the tooth bottom is located at a forward offset from a center line of the tooth bottom with respect to a direction of rotation of the roller.

Abstract: Forming rollers having a tooth tip concave portion at the tip of a tooth tip portion, a tooth bottom convex portion at a bottom of a tooth bottom portion and louver cutter at an oblique line portion between the tooth tip portion and the tooth bottom portion. A radius of an arc-shaped portion of the tooth tip concave portion at front side of rotational direction is set to be larger than a radius of an arc-shaped portion of the tooth tip concave portion at a rear side of the rotational direction. A radius of an apex portion of the tooth tip portion at the front side is set to be smaller than a radius of an apex portion of the tooth tip portion at the rear side and louver cutter at the oblique line portion is formed to have a predetermined interval from the apex portions of tooth tip portion. Therefore, flat folded portions having substantially the same curvature at both shoulder portions thereof horizontal are formed.