Cold Extrusion of Spur Gear with Inner Spline

Abstract

The shaping conditions for a spur gear with an inner spline by cold extrusion are examined experimentally. The specifications of the spur gear examined are as follows: module m=1.25-2.0, number of teeth Z=18-13, pressure angle α=20°, and tooth depth h=2.25m; those of the inner spline are as follows: module ms=1.0, number of teeth Z=8-18, pressure angle α=20°, and tooth depth hs=1.25m. The tested material is low-carbon steel, S15C. The inner diameter of the workpiece, inner spline tooth depth, addendum modification coefficient, and module are varied to examine the effect of the reduction in area. It is found that well-shaped spur gears and inner splines can be produced. The shaping conditions are closely connected with the reduction in area. The accuracy of the shaped spur gear was about 7 Grade in the old JIS. The punch pressure needed for the shaping is much lower than the strength of the punch material.