Pre-straightening machine is a device for preliminary straightening of metal profiles, bars, pipes, wires, etc. The pre-straightening machine changes the straightness by pressing the bar or the like through the straightening roller. It consists of a pinch device, a horizontal inversion and a vertical device.

Principle of straightening machine: The bending part of the steel is subjected to considerable reverse bending or stretching, so that a certain elastic-plastic deformation occurs in this part. When the external force is removed, the steel undergoes elastic recovery and then reaches straightness.