Analysis of pipe piercing operation by finite element method

At present, making holes in long steel pipes can be carried out in many ways. The use of a piercing punch with a die mandrel is a popular method because it can quickly produce workpieces, improve productivity, and good reproduction part quality. The main problem with this operation is a collision between punch and mandrel especially a long mandrel due to elastic deflection. Investigations have been made on the deformation pattern of pipe pierced by punch with 3 different end profiles; flat, rectangular, and concave. The experiments showed that elastic deflection of pipe took place during pierce changing from round into oval cross-section. In order to avoid that, 2 types of support were designed; internal support and external support. It was found that the quality of pierce hole using rectangular punch with external support of proper clamping force was comparable to that using punch with die mandrel.