火炮身管(厚壁圆筒)机械自紧理论探讨

A THEORETICAL STUDY ON THE SWAGE AUTOFRETTAGE OF GUN TUBES (THICK-WALL HOLLOW CYLINDERS)

结合实验具体分析了机械自紧机理，并建立了理论计算公式，通过与实验数据比较，误差很小。由于机械自紧有较大的轴向残余应力（约相当于65％切向残余应力），正好抵抗了火药气体的冲刷和弹丸的摩擦，所以不单具有同液压自紧一样提高炮管强度的作用，同时有提高炮管寿命的作用。

Autofrettage is a useful technique to increase the fire power of modern ar-tillery.However,the technical parameters,residual stress,permanent enlargement in ID and OD for an article autofrettaged have so far been calculated by a formula under the assumption that no axial force exists and the axial stress is zero (or constant).Although the presence of axial acting force and axial stress is proved to exist in the swage autofrettage process,no theoretical analysis and calculation of the axial stress can be found in the literature.This paper analyzes the mechanism of swage autofrettage process through experimentation and develops a theoretical formula for the calculation agreeing well to the experimental data.Featuring a large axial residual stress (equal to about 65% of the tangential residual stress)just enough to resist the erosion by powder gases and rubbing by projectiles,the swage autofrettage is comparable to the hydraulic autofrettage as to the effect in increasing the strength of gun tube,thus prolongins its service life,so this process is also applicable in the civil industry to produce cylindrical or tubular products which are to work under high pressure.