JPS6444220A - Production of metallic bellows - Google Patents

Abstract

PURPOSE:To uniformize the thickness of a bellows and to extend the bellows life by forming the root part of the waved pipe of a 1st forming so as to become the bellows crest part of a 2nd forming. CONSTITUTION:The forming of a waved pipe 12 is executed by inserting a pipe stock 1 into the split stationary dies 5a-5d arranged at equal pitch, subjecting to pressure sealing and executing bulging by exhausting the air and exerting a hydraulic pressure 2. The stress relief annealing of the waved pipe 12 is executed then. The waved pipe 12 is then inserted into movable dies 8a, 8b, 8c, subjected to pressure sealing with the movement of 1st, 2nd sealing dies 7a, 7b and fitted so that the crest part of the waved pipe becomes of the bellows root part 11b and the waved pipe root part of the bellows crest part 11a. The forming is executed by the hydraulic pressure 2 and after completing of the specified bulging axial forces 9a, 9b are loaded, the sealing dies 7a, 7b are driven in an arrow mark 10 direction and the crest part of the bellows is folded in order to execute forming. The thicknesses of the bellows shaped root and crest parts are uniformized and the spring constant can be reduced.