互余法方管孔型设计

对现有几种先焊接为圆管后成型为方管的孔型设计方法进行了评述。提出一种新的方管孔型设计方法──互余法。它以方管的直线段和过渡圆用所对应的管坯弧长在变形过程中基本保持不变为设计原则，使两部分弧长对应的圆心角保持互为90°。该法设计简单，变形参数易于设定和调整，且成形精确，有利于提高产品的尺寸精度。

A PASS DESIGN METHOD OF SQUARE PIPE FORMING

The present pass design methods for forming welded circular pipe into square pipe are summaried. A new pass design program of square pipe forming, mutual complement method is given. The design principle is that pipe arc lengths corresponding the straight-line side and transition round angle of square pipe are kept unchanged in the process of forming, and central angles corresponding the two arc lengths are kdpt each other complement. The method is simple for calculating and accurate for forming, the forming parameters are easily given and adjusted. So, it is advantageous to the improvement of product size precision.