1. the appropriate bend radius value, it tube bending radius size, determines the size of the catheter in the resistance to bending. In General, tube diameter and small bending radius, prone to wrinkles and to skid when bent, bending is difficult to ensure the quality, so choose the r value of pipe-bending die for the pipe diameter 23 times as well. 2. regularization, design and pipe to avoid excessive arc, arbitrary curves, combined bending and more than 180. Arc. Large Arc tool will not only heavy and tube bending machine tool size of arbitrary curves and compound bending is not reasonable for the design greatly impeded mechanization and automation of production, making it difficult for operators to get rid heavy manual labour; more than 180. Arc bending machine cannot be unloaded mode.