Cold Extrusion of Spur Gear with Inner Spline with Reductionin Outer Diameter or Expansion of Inner Diameter of Workpiece

Abstract

The shaping conditions for a spur gear with an inner spline by cold extrusion by reducing the outer diameter or expanding the inner diameter of the workpiece were examined experimentally. The specifications of the spur gear examined are as follows: module m=1.0-2.0, number of teeth Z=22-13, and tooth depth h=2.25m; those of the inner spline are as follows: module ms=1.0, number of teeth Z=8-16, and tooth depth hs=1.25m. The tested material is low-carbon steel, S15C. The outer and inner diameters of the workpiece, inner spline tip diameter, and mandrel small and large diameters were 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 6~8 Grade in the old JIS. The punch and mandrel needed pressure for the shaping are much lower than the strength of the material.