GEAR FORMING METHOD AND DEVICE THEREOF

摘要

PROBLEM TO BE SOLVED: To surely secure the strength of a double stage gear having a spur gear and a helical gear and increase yield of raw material and simplify the manufacturing process and reduce the manufacturing cost. SOLUTION: A gear forming device 10 has a fixed part 14 and a movable part 16. The fixed part 14 is provided with a center guide 24, a lower punch 40 which is rotatable on the outer peripheral face of the center guide 24 and a die 84 by which the helical gear tooth forming part 86 is cut in the inner peripheral part. The angleθof the tooth 87 of the helical gear tooth forming part 86 is set 30<θ<45 deg. with regard to the axial direction. The movable part 16 is provided with a mandrel 96, an insert punch sleeve 98 fitted in the mandrel 96, and the upper punch 112 which is slidable on the outer peripheral face of the insert punch sleeve 98. A spur gear forming part 136 is cut in the tip of the inner peripheral face of the upper punch 112.