When using hydraulic pipe bender to design and discharge pipes, excessive circular arc, arbitrary curve, compound bend and greater than 180 degrees shall be avoided. Arc of too large circular makes the tooling to be bulky and is limited by the size of the hydraulic pipe bender itself. The design and modeling of arbitrary curve and compound bend are very unreasonable, which greatly hinders the mechanized and automatic production and make it difficult for the operator to get rid of heavy physical labor. Greater than 180 degrees, the circular arc makes the tube bending machine unable to unload the die.

Bending radius is tried to achieve “one mold for one pipe or several pipes”. For one pipe, there is only one bend radius in any bending and bending angle, because we will not replace the mold in bending process by the hydraulic bending machine, which is “one mold for one pipe”. One mold for several pipes, means that the same type of mold can be used to bend different shapes of tubes so that the number of modules can be reduced.

The bending radius of hydraulic pipe bender determines the resistance of pipe during bending forming. Generally speaking, the pipe diameter is large and the bending radius is small, so it is easy to wrinkle and slip during bending, and the bending quality is difficult to ensure. Therefore, it is generally better to select the R value of the bending die as 1.5 times of the pipe diameter.

Set moderate bending speed. If the speed is too fast, it is easy to cause the flat bending part of the pipe, and the roundness cannot meet the requirements, which is resulting in the tensile crack and fracture of the pipe; If the speed is too slow, it is easy to wrinkle the pipe and slide the compression block, and for the pipe with large diameter, it is easy to form the subsidence of the bending part of the pipe. According to a large number of tests on the hydraulic pipe benders, the bending speed of the pipe should be determined as 20% - 40% of the bending speed of the pipe bender.

The mandre of metal pipe bending machine mainly plays the role of supporting the inner wall of pipe bending radius and preventing its deformation in the bending process. At present, domestic pipes are bent on machine tools. If mandrel is not used, its quality is difficult to guarantee. There are many forms of mandrel, such as cylindrical mandrel, universal single, double, three and four ball head mandrel, directional single and multi-ball head mandrel, etc. In addition, the position of the mandrel also has a certain impact on the bending forming of the pipe: theoretically, its tangent should be flush with the tangent of the bending die, but a large number of tests show that it is better to advance 1mm to 2mm, and the bending quality is ideal at this time. Of course, too much advance will cause the so-called “goose head” phenomenon on the outer wall of the bending part.