论文部分内容阅读
自紧(Autofrettage)亦称自增强。它是在厚壁圆筒内部施加超高压力使其发生塑性变形,卸压后在内膛产生一负的余残应力(预应力),从而可抵消一部分工作压力作用的影响,使得圆筒的弹性强度得以提高。该方法目前已普遍用于提高火炮身管、化工容器及石油机械泵头等超高压容器的强度与使用寿命。一些国外学者指出,当不考虑材料的鲍兴格效应(Bausohinger Effeot)影响并设卸载是弹性的,则所施加的内压力就等于塑性变形后身管的强度值(即理论强度)。然而大量的实践表明,由于材料的实际性态的影响,自紧身管的实际强度值小于理论强度值。因而,如何精确地测量这个实际强度,换言之,即如何控制塑性变形方可使得自紧身管的实际强度能够满足工程设计上许用强度的要求,就成了自紧研究的重要课题之一。本文给出了一个根据打压时外表面应变信息计算自紧身管实际强度的数学模型。并用微电脑建立了测定实际强度的实时处理与控制系统,实现了自紧操作的自动处理,明显地提高了测量精度。它对自紧工艺的自动化和测试定型将具有重要意义。
Autofrettage is also known as self-enhancement. It is in the thick-walled cylinder to exert super-high pressure plastic deformation, pressure relief in the bore to produce a residual residual stress (prestress), which can offset part of the role of the working pressure, making the cylinder Elastic strength can be improved. The method is now generally used to enhance the strength and life of the barrel, chemical containers and mechanical pump head UHP containers. Some foreign scholars have pointed out that the applied internal pressure is equal to the strength value (ie, the theoretical strength) of the ducts after plastic deformation, irrespective of the material’s Bausohinger Effeot effect and the unloading elasticity. However, a great deal of practice shows that due to the actual behavior of the material, the actual strength of the self-tight tube is less than the theoretical value. Therefore, how to accurately measure this actual strength, in other words, how to control the plastic deformation so that the actual strength of the self-tight tube can meet the requirements of engineering design allowable strength becomes one of the important topics of self-tightness research. This paper presents a mathematical model that calculates the actual strength of the self-contained tube based on the strain information on the outer surface during compression. The real-time processing and control system for measuring the actual strength was established by microcomputer, which realized automatic processing of self-tightening operation and obviously improved the measuring accuracy. It will be of great importance to automating and testing the self-tightening process.