In the case of bending pipe, the outter diameter (D) and wall thickness (T) is bent by the external moment (M), the tensile stress σ1 on the outer tube wall of the neutral layer becomes thinner; the inner tube of the neutral layer is thinner. The wall tensile stress σ1 acts to thicken the tube wall. Moreover, the shape of the cross section changes from a circular shape to an approximately elliptical shape due to the combined forces F1 and F2. When deformation is too large, the tube outer wall will has cracks, inner tube wall will have wrinkles.  So why is the arc of the square tube bender reduce thinner?

The boosting and pushing speeds are determined according to the actual conditions of the pipe bender to match the speed of the hydraulic pipe bender. At the same time, it is necessary to check whether the advancement of the core rod installation is appropriate, and if necessary, make necessary adjustments. Based on the external bending of the pipe arc, the cause should be carefully analyzed. First of all, the pipe must be in a good heat treatment state. The welded seam of the steel pipe should not be in the direction of the force of F1 and F2, that is, do not face the clamping. Molds and curved wheel molds; after excluding the factors of the pipe, check whether the pressure of the pressing mold is too large, and adjust to make the pressure appropriate.

For new mandrel, it needs to check whether the diameter is too large. When the diameter is too large, perform necessary grinding and ensure that the mandrel rods and the inner wall of the tube have good lubrication to reduce the bending resistance and the friction between the inner wall of the tube and the mandrel rod. At the same time, take appropriate measures to avoid machine shake. For wrinkling inside the arc, corresponding measures should be taken according to the wrinkling position. If wrinkling at the forward cutting point, the position of the core rod should be adjusted forward so that the core rod is properly advanced in order to achieve reasonable support for the tube when bending. The wrinkle at the back cut point should be equipped with anti-wrinkle blocks and the installation position of the anti-wrinkle blocks is correct. It can be attached to the hydraulic pipe bending machine mold well, and the pressure of the pressing die (wheel) must be adjusted to make the pressure appropriate.

In order to maintain the efficiency and the safety of the cnc pipe bending machine , an effective machine inspection and maintenance plan must be in place and implemented according to regulations. The life of the relay, solenoid valve or other electrical and mechanical parts depends on the test use method, environmental conditions and complete preventive maintenance plan. Wear and tear or improper repairs can cause a part to fail at any time. Frequent inspections and a good preventive maintenance program can reduce the possibility of mistakes. Worn or non-repairable parts must be replaced immediately. The clean environment around the machine makes any inspection and maintenance easier. It is also important to keep the floor around the machine clean and free of debris.