摘要
根据基本假设 ,建立双金属复合管的材料模型及力学模型。采用弹塑性理论 ,分析双金属复合管液压成形过程中内管及外管的应力应变状态。利用变形协调条件 ,得出液压力Pi 与复合管内外管之间残余接触压力P c 的计算公式 ,给出液压成型压力的最大值与最小值 ,并通过试验验证理论公式的准确性。双金属复合管复合成形时要想获得残余接触压力 。
The double-wall, bimetallic CRA-lined pipe has an inner layer made of a very resistant CRA and an outer layer made of low-cost carbon steel providing the line pipe with the required strength and toughness, which has been widely applied in oil production, nuclear power plants and refining industry. Clad pipe can be manufactured by various techniques that include hot coextrusion, hot-rolled bonding, explosive bonding, centrifugal casting and hydraulic expansion of a CRA pipe inside and a carbon-steel outer pipe. Compared with kinds of methods, hydraulic expansion process is easy to control, clad pipe can be economically manufactured and its quality is better, so it is deserved to develop. This paper mainly presents the clad pipe, which inner pipe is stainless steel and outer pipe is carbon steel to be formed by hydraulic expansion process. According to the basic supposition,the material and mechanics models of inner pipe and outer pipe have been established. (1) The material of the inner piper is considered as linear hardening behavior, and the outer pipe is described as ideally plastic material since its plastic deformation is smaller. (2) During the hydraulic expansion, the axial force in pipes can be neglected according to our experimental model, so the stress on pipes can be got by simplified as problem of planar stress. The main principle of hydraulic expansion process for clad pipe has been described. Adopting the elasticity-plasticity theory, the stress and strain during loading and the residual stress and strain after unloading for the inner and outer pipe of clad pipe have been discussed. By using the distortion matching condition the calculating formulas related hydro-forming pressure to the residual contact pressure between has been derived. The range of expansion pressure is got according to the different demands for residual contact pressure of clad pipe, and the maximum and minimum value of hydro-forming pressure is given. In order to obtain the residual contact pressure, the yield stress of outer pipe must be more than inner pipe or it's hardening stress. The theoretical analysis is verified by experimental results.
出处
《机械强度》
CAS
CSCD
北大核心
2002年第3期439-442,共4页
Journal of Mechanical Strength
关键词
复合管
液压成型
残余接触压力
Clad pipe
Hydro-forming
Residual contact pressure
