近似展开方法对椭圆形封头强度影响的研究

椭圆形封头表面属不可展曲面，在加工制造时需将封头曲面等分，每一份都用可展曲面近似代替的方法进行展开、下料、弯卷，最后焊接成椭圆形封头。显然，实际制造出来的椭圆形封头形状与其理论形状之间有一定的误差，对承受中低压力的椭圆形封头，可由微体平衡方程和区域平衡方程算得设计壁厚。由于计算的依据是椭球面的理论形状，所以得到的壁厚比近似展开曲面对应的壁厚要薄。分析近似展开方法对壁厚计算的影响，得出理论计算壁厚的补偿量，避免以增加安全系数加大壁厚的盲目性，也为各种近似展开方法的合理性判断提供了理论依据。

Research on Approximation Development Method Influence on Strength of Oval Seal Head

The surface of a oval seal head is a double-curved surface that can be developed only by some approximate method.Obviously,there are some errors between actual manufacturing oval seal head and its theories shape.For the middle or low-pressure vessel,according to shape of its theories the designing wall thickness can be calculated by equilibrium equation of elementary volume and the equilibrium equation of district.But it is to take theories shape of oval seal head as calculating basis,to obtain wall thickness of oval seal head is thinner than correspondent wall thickness which is developed only by some approximate method.This paper analysis approximate developing method influencing wall thickly calculation,avoiding blindness that is increased wall thickness by increasing safe coefficient,and also provided thd theories basis for judgment of every kind of approximate developing method.