拉伸装夹改变铣削残余应力的机理研究

基于平面应变的热弹塑性理论分析了拉伸装夹加工残余应力的形成原理，建立了拉伸装夹加工的应变叠加模型，认为残余应力由加工表面的塑性应变决定，而加工表面的塑性应变是加工过程引入的塑性应变和拉伸装夹产生的初始弹性应变之和. 开展了TC4钛合金的拉伸装夹铣削试验，铣削速度从38m/min到566m/min，拉伸装夹产生的初始应变从0和3.0‰, 铣削完成后，在铣削面内与拉伸方向呈0、30、90、120度的四个方向上分别测量了残余应力.试验结果表明在四个测量方向上拉伸装夹引起的残余应力变化量和产生的初始弹性应变一是致的，验证了应变叠加模型的正确性。

Study on modification mechanism of milled surface residual stress with stretching fixation

The generation of residual stress in stretching fixation-machining was analyses based on plane strain thermoelastoplastic theory, and a strain superposition model for stretching fixation-machining was proposed. It was considered that the residual stress was decided by plastic strain in machined surface layer, which was the sum of plastic strain induced by machining process and initial elastic strain produced by stretching fixation. Stretching fixation-milling of TC4 titanium alloy had been completed under the condition of the initial strain produced by stretching fixation ranged from 0 to 3.0‰ and the milling speed ranged from 38m/min to 566m/min, and the residual stresses in machined surface were measured in directions of 0, 30, 90 and 120 degree relative to stretching direction respectively. Experiment results indicated that the residual stresses variations were consistent with the initial elastic strains in measured directions, which verified that the strain superposition model was acceptable.