讓現已加工成制品方管具有較小曲折度還得依靠機械東西校直機來完結。所以為了消除方管曲折，一切方管都需求經過冷校直。方管曲折是因為軋機調整不妥，軋制時殘留的剩余應力以及因為沿管子截面和長度上冷卻不平等緣由形成的。因而，不行能從軋機直接得到很直的管子，只要通過冷校直管子的曲折度才干滿意技能條件的規則。

To make the square tubes of the products processed now have a small degree of flexibility, we have to rely on the mechanical straightening machine to complete the straightening machine from east to west. Therefore, in order to eliminate the twists and turns of square tubes, all square tubes need to undergo cold straightening. The bending of square pipe is caused by improper adjustment of rolling mill, residual stress during rolling and unequal cooling along the section and length of pipe. Therefore, it is impossible to get very straight pipes directly from the rolling mill. Only by cold straightening the pipe's flexibility can the rules of skill conditions be satisfied.

校直的根本道理即是使方管進行彈塑性曲折，由大的曲折度成為小的曲折度，因而鋼管在校直機內有必要遭到重復曲折。而鋼管重復曲折的程度主要由校直機的調整所決議。

The basic principle of straightening is to make square pipe elastic-plastic twist, from large twist to small twist, so it is necessary for steel pipe to be repeated twist in straightening machine. The degree of repeated twists and turns of steel pipe is mainly determined by the adjustment of straightening machine.

影響校直質量的要素許多，如原管的曲折度，鋼管尺度和材料校直機型式，調整參數等。

There are many factors affecting the quality of straightening, such as the bending degree of the original pipe, the size of the steel pipe and the type of straightening machine for materials, and the adjustment of parameters.