ラック形工具による転造歯車素材の割り切り

Abstract

In cold roll forming, gear teeth are generally formed from rotating gashed blanks between a pair of rack dies. The blanks used for rolling are smaller in diameter than the outside diameter of the finish part. And therefore, any variation in the diameter of the blank is magnified in variation in the outside diameter of the rolled part. In this paper, the experiments were devoted to forming proper number of notches on the peripheries of the blanks, using the cold rack die system. The pinions (module m=1.5,10mm tooth width) of 27 or 33 teeth were used, and the teeth gashes in each pinion blank were 1mm deep. Owing to produce the accurate timing notches on the pinion blanks, several problems should be considered. For example, the expected dividing number and the notched shapes of the pinion blank are varied with the blank diameter, the length of the effective die teeth, crest curvature at the top flank, pressure angle of the rack dies and synchronized notching velocity etc. From these experiments, the desirable shape of rack die and the outside diameters of the pinion blanks were able to be estimated.