Method for integrally manufacturing an one-piece forged hollow crank of a bicycle

摘要

A method for integrally forming and manufacturing an one-piece forged hollow crank of a bicycle includes the following steps: (a) forging and molding a leading edge of a crank; (b) extruding a crank body; (c) forging and possibly sealing a rear end of the crank body; and (d) cutting and piercing the rear end of the crank body so as to form a hollow crank of a bicycle. In such a manner, the hollow crank can be integrally forged and molded quickly by fewer manufacturing steps than that of the conventional method. In addition, the product surface of the hollow crank is finished to have a fine and pretty appearance so that it is not easy to produce a defective product, thereby enhancing the aesthetics and quality and saving the manufacturing cost of hollow crank. Further, better aluminum alloys can be used with this method than can be used with the prior art casting or welding methods.