METHOD AND DEVICE FOR FORMING UNIVERSAL JOINT

摘要

PURPOSE:To form a center groove to an exact position with high accuracy by applying a back pressure to the rear face of a cup part by an oil pressure and strongly pressing the rear face of the cup part by an upper die so that the center groove is coined to the base of the cup part by a center spacer. CONSTITUTION:A punch 14 is moved by a cam face 13a toward the bore of a stock 6 to press the outside peripheral face 6c of the cup part 6a when the cup part 6a of a stock 6 is put on a mandrel 7 and the center spacer 9 and the upper die 12 is lowered after the cup part is housed into a lower die 5. The groove is thus coined on the inside peripheral face 6b of the cup part 6a by the mandrel 7. A work holder 15 contacts the rear face 6 of the cup part 6a at this time and the back pressure is applied to the rear face 6d by a hydraulic cylinder 17 to prevent floating up of the stock 6 during coining of the groove. A top surface 19a of a piston of the hydraulic cylinder 17 contacts the top surface 18a of the cylinder part 18 just before the bottom dead point of the stroke of the upper die 12, then the die 12 and the holder 15 are rigidly connected to strongly press the rear face 6d of the cup part 6a of the stock 6. The center groove is thus coined to the rear face by the center spacer 9.