公开(公告)号：US3689969A

公开(公告)日：1972-09-12

申请号：US3689969D

申请日：1970-07-29

Applicant: TSUNODA JITENSHA KABUSHIKI

Inventor： TSUNODA MASASHI

IPC: B21D53/86 ,  B21K1/76 ,  B23P13/00

CPC classification number: B21K1/76 ,  B21D53/86

Abstract: A method of forming a claw portion of the front wheel journal fork of a bicycle, including the steps of axially squeezing a metal pipe, having one end of reduced section, between a pair of chuck electrodes, the electrode seating said reduced section end of the pipe having a die cavity of a desired shape for an intermediate form of the claw portion, while simultaneously applying an electric potential to said electrodes, whereby to soften and form said reduced section end of the pipe to a shape conforming to that of the die cavity, pressing said shaped end of the pipe to flatten said end, shearing said flattened end to a desired claw contour, and punching a hole and a slot in said flat and contoured claw portion.

Abstract translation: 一种形成自行车的前轮轴颈叉的爪部的方法，包括以下步骤：在一对卡盘电极之间轴向挤压具有减小截面的一端的金属管，所述电极将所述减速部的端部 管，其具有用于中间形式的爪部的所需形状的模腔，同时向所述电极施加电位，由此软化并形成所述管的所述缩小部分端部至符合模腔的形状 按压所述管的所述成形端使所述端部平坦化，将所述扁平端部剪切成所需的爪轮廓，并在所述平坦且成形的爪部中冲压孔和槽。