Flower pattern and roll positioning design for the cage roll forming process of ERW pipes

The cage roll forming process improves the flexibility of electrical resistance welding (ERW) pipes manufacturing by employing several groups of cage rolls, but poses great challenge to flower design and roll positioning, since the flower pattern and rolls' positions are no longer one-to-one correlated as in conventional roll forming processes. In the present work, a forming flower design method for cage roll forming of ERW pipes is proposed, considering the transversal bending characteristics of the sheet metal, especially the existence of “non-bending area”. Furthermore, based on kinematic analysis of the cage roll frame, a roll positioning method is put forward by implementing flower pattern and enforcing the geometric constraint condition between rolls and the steel strip. The proposed flower pattern design and roll positioning methods are demonstrated by the cage roll forming of two ERW pipes. The forming processes by using the newly designed parameters and old experience based parameters are compared. The proposed method provides a science based process design method for cage roll forming processes. To the best of our knowledge, the present work is the first effort on developing flower pattern and roll positioning design methods for the cage roll forming process of ERW pipes.