Solution to the bulging problem in the open-die cold extrusion of a splineshaft and relevant photoplastic theoretical study

Compared with other forming methods, the cold extrusion of a spline shaft h as many advantages. However, the problem of bulging at the die entrance, wh ich is not yet solved, resists the wide application of this net (or near ne t) shape technology. To solve the bulging problem, the method of adding a g uiding length upon the die entrance in the die designing is put forward in this paper. On the basis of photoplastic experiments, a theoretical analysi s model of the solution is found, and the calculating method for the guidin g length is also submitted. The appropriate processing parameters are chose n based on the calculated results, and a satisfactory effect has been obtai ned in the actual processing. (C) 2001 Elsevier Science B.V. All rights res erved.