Spline forming of ultra-high strength gear drum using resistance heating of side wall of cup

A spline forming process of an ultra-high strength steel gear drum using resistance heating of a side wall of a cup formed by cold deep drawing and ironing was developed. The side wall having uniform cross-sectional area was heated by the electrification in the axial direction. The uniformity of the temperature was improved by inserting copper foils between the electrode and the side wall, and by decreasing the area of contact. Although the high strength steel cup was fractured by cold spline forming, the gear drum was successfully formed by the heating.