The boosting and pushing speeds are determined according to the actual situation of the pipe bending to match the speed of the hydraulic pipe bending machine. At the same time, check whether the advance of mandrel installation is appropriate, and adjust if not. Based on the outside bending crack of pipe arc, the reason should be analyzed carefully. First, the pipe should be in good heat treatment state. The weld of seam steel pipe should not be in the stress direction of F1 and F2 as far as possible, that is, not facing the clamping die and bending wheel die. After eliminating the factors of pipe, check whether the pressure of pressing die is too large, and adjust the pressure to make it appropriate.For the newly used mandrel, it is necessary to check whether its diameter is too large. When the diameter is too large, it is necessary to grind it, and ensure that the mandrel and the inner wall of the pipe have good lubrication, so as to reduce the resistance of the elbow and the friction between the inner wall of the pipe and the mandrel. At the same time, appropriate measures are taken to avoid the shaking of the machine tool. For the inner wrinkle of the circular arc, corresponding measures should be taken according to the wrinkling position. If the front point is wrinkled, the position of the mandrel should be adjusted forward so as to make the mandrel advance ahead of time, so as to achieve the reasonable support for the pipe when bending. If the back tangent point is wrinkled, an anti wrinkle block should be added to make the installation position of the anti wrinkle block correct, which can be attached to the die of the pipe bender, and the pressure of the pressing die (wheel) should be adjusted to make the pressure appropriate.