共查询到20条相似文献,搜索用时 250 毫秒
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在弹塑性理论的基础上,建立了三维铣削仿真加工变形场的有限元分析模型,利用“单元生死”技术仿真了加工过程中材料的去除研究了零件在加工过程中因毛坯初始残余应力的释放而引起的工件加工变形规律设计了典型零件的数控加工变形试验,使用三坐标测量仪测量了每次材料去除后产生的变形通过仿真数据与试验数据比较分析,数据结果表明,只要建立正确的三维有限元分析模型,完全可以实现对零件加工变形规律的预测,从而制定出减小工件加工变形的合理加工工艺. 相似文献
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《机械制造与自动化》2016,(5)
薄壁结构件的整体轮廓变形主要是由其毛坯内部残余应力重新分布而引起的,根据双面槽腔薄壁结构件的结构特点建立了薄壁件铣削加工的有限元模型,系统地研究了残余应力的施加,材料去除加工过程所涉及的关键技术,并通过优化薄壁整体结构件的装夹方案以及多个特征结构的加工顺序,控制了薄壁整体结构件的加工变形。 相似文献
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为提高飞机性能,整体结构件成为飞机广泛采用的主要承力构件,而整体结构件毛坯由于残余应力的存在往往导致加工后出现较大变形影响零件精度。根据模锻毛坯件的残余应力测试试验数据,逆向构建了初始应力仿真模型,采用用户子程序SIGINI施加初始应力场,运用生死单元法对分层材料进行去除。结果表明,通过表层残余应力试验数据逆向构建初始残余应力分布场计算变形的可行性,同时可以直观分析生死单元法逐层杀死单元过程中,初始残余应力的释放过程,与零件加工后的变形测量结果对比,有较高的吻合性。 相似文献
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铝合金预拉伸板在成型过程中会产生较大的残余应力,在切削过程中毛坯的初始残余应力的释放对整体结构件的宏观变形有重要的影响。在弹塑性力学的基础上,综合运用Hypermesh和ABAQUS建立残余应力单因素作用下的三维铣削仿真加工变形场的有限元模型,利用生死单元技术模拟了材料的去除,分析了铝合金板材材料去除过程中残余应力释放引起的加工变形规律。并且运用Hypermesh提高了有限元前处理的速度,解决了复杂模型的残余应力加载困难与单元去除困难的问题。 相似文献
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弱刚度结构件具有刚度差和材料去除量大等特点,加工过程中产生的残余应力容易导致其加工变形,尤其对于精度要求高且厚度不均匀的弱刚度结构件,更有必要研究切削加工残余应力的影响因素,从而为控制弱刚度结构件的加工变形提供基础。根据正交切削理论和热弹塑性有限元理论建立了切削加工的三维有限元模型,对材料为40CrNiMo的变厚度弱刚度结构件进行了切削加工模拟,对切削过程中的残余应力进行了有限元计算。通过对比不同切削参数情况下残余应力的分布,得到了残余应力随切削参数的变化规律;将变厚度弱刚度结构件的加工分为二次等厚度的切削加工,通过与一次加工得到的残余应力进行对比,得到了2种不同加工工序对变厚度弱刚度结构件的残余应力影响规律。 相似文献
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针对薄板类零件加工过程中加工变形导致加工精度低的问题,利用有限元法和高斯过程回归算法建立了加工变形预测模型,综合考虑机床运动误差与工件加工变形,对薄板件加工精度可靠性进行分析,建立了以加工效率和平均加工变形为目标、加工精度可靠度为约束的铣削加工工艺参数优化设计模型,并利用多目标优化算法进行求解,确定了协调加工效率和加工变形最优的工艺参数组合。案例研究结果表明,经优化设计后最低加工精度可靠度达到98.21%,平均加工变形减小21.14%,加工效率提高了4.18%,为薄板类零件铣削加工工艺参数选择提供了一种可行的方法。 相似文献
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Zheng Zhang Liang Li Yinfei Yang Ning He Wei Zhao 《The International Journal of Advanced Manufacturing Technology》2014,73(9-12):1765-1773
The distortion of machined parts is a major concern in the manufacture of aeronautical monolithic structures. We investigated the influence of material removal partition on residual stress in high-strength aluminum alloy parts to minimize machining distortion. In the present study, a methodology of minimizing machining distortion based on an accurate cross-sectional residual stress determination is presented, which can be applied to avoid or minimize part distortions in advance by adapting machining strategies or process conditions. A powerful contour method was used first to measure bulk residual stress within the blank. Next, a finite element model was applied to predict machining distortion based on measured residual stress for analyzing part distortion. Finally, experimental verification was provided by comparing measured distortion and predicted distortion by the finite element analysis. This simulation showed that part distortion is mainly affected by the partition of material removal in T-shaped components. Our results also indicate that distortion can be minimized by optimizing the partition of material removal to ensure a symmetrical distribution of residual stress in the part so that the residual stress-induced bending moment could reach self equilibrium. 相似文献
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Z. T. Tang T. Yu L. Q. Xu Z. Q. Liu 《The International Journal of Advanced Manufacturing Technology》2013,68(1-4):187-196
The machining deformation prediction model was developed considering multifactor coupling effects including original residual stresses, clamping loads, milling mechanical loads, milling thermal loads, and machining-induced residual stresses. The machining deformation of a true frame monolithic component was predicted by this model. To validate the accuracy of prediction model, deformations also were measured on a coordinate measuring machine. The deformations predicted by the model show a good agreement with the experiment’s results. The deformation prediction model can provide an effective way to study further control strategies of machining deformations for monolithic component. 相似文献
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Double-sided lapping is an precision machining method capable of obtaining high-precision surface. However, during the lapping process of thin pure copper substrate, the workpiece will be warped due to the influence of residual stress, including the machining stress and initial residual stress, which will deteriorate the flatness of the workpiece and ultimately affect the performance of components. In this study, finite element method (FEM) was adopted to study the effect of residual stress-related on the deformation of pure copper substrate during double-sided lapping. Considering the initial residual stress of the workpiece, the stress caused by the lapping and their distribution characteristics, a prediction model was proposed for simulating workpiece machining deformation in lapping process by measuring the material removal rate of the upper and lower surfaces of the workpiece under the corresponding parameters. The results showed that the primary cause of the warping deformation of the workpiece in the double-sided lapping is the redistribution of initial residual stress caused by uneven material removal on the both surfaces. The finite element simulation results were in good agreement with the experimental results. 相似文献
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Machining-induced residual stress distribution is strongly influenced by the machining process condition, tool geometry and workpiece material mechanical properties. The high temperature, large strain and high strain rate environment will promote the material micro-structural attribute changes. The material micro-structural attribute changes could directly affect the material mechanical properties. An analytical model is proposed for the residual stress prediction in the orthogonal turning by considering the material dynamical recrystallization induced grain growth effect. The grain size effect on the material flow stress behavior is included by adding a grain size dependent term into the traditional Johnson–Cook model. The Johnson–Mehl–Avrami–Kolmogorov model calculates the recrystallized volume fraction and grain size as a function strain, strain rate and time. The average grain size is calculated with a rule of mixture by volume. Then the modified Johnson–Cook model is embedded into a classic residual stress prediction model for the machining induced residual stress profile prediction on the machined workpiece surface. Experimental tests are conducted for the model validation. The predicted residual stress shows good approximation with the measurement in both the trend and magnitude of the residual stress. Also, the effects of cutting speed and feed rate on the residual stress profile are investigated. 相似文献
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Comparison and analysis of main effect elements of machining distortion for aluminum alloy and titanium alloy aircraft monolithic component 总被引:1,自引:0,他引:1
Y. Yang M. Li K. R. Li 《The International Journal of Advanced Manufacturing Technology》2014,70(9-12):1803-1811
Main effect elements of machining distortion for aluminum alloy and titanium alloy aircraft monolithic component are investigated by finite element simulation and experiment. Based on an analysis of milling process characters, finite element models of machining distortion are developed. Considering the action of initial residual stress, finite element simulation and analysis of machining distortion for aluminum alloy aircraft monolithic component are performed. Initial residual stress, cutting loads, and coupling action of these two effect factors are taken into account, respectively, to perform finite element simulations of machining distortion for titanium alloy aircraft monolithic component. The finite element simulation results are compared with experiment results and found to be in good agreement, indicating the validation of the proposed finite element models. The research results show that the initial residual stress in the blank is the main effect element of machining distortion for aluminum alloy aircraft monolithic component, while cutting loads (including cutting force and temperature) are the main effect element of machining distortion for titanium alloy aircraft monolithic component. To decrease machining distortion of aluminum alloy aircraft monolithic component, the initial residual stress in the blank must be controlled first. Similarly, to decrease machining distortion of titanium alloy aircraft monolithic component, the cutting loads must be controlled first. 相似文献
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S. Selvakumar K. P. Arulshri K. P. Padmanaban K. S. K. Sasikumar 《The International Journal of Advanced Manufacturing Technology》2013,65(9-12):1573-1586
In machining fixtures, minimizing workpiece deformation due to clamping and cutting forces is essential to maintain the machining accuracy. This can be achieved by selecting the optimal location of fixturing elements such as locators and clamps. Many researches in the past decades described more efficient algorithms for fixture layout optimization. In this paper, artificial neural networks (ANN)-based algorithm with design of experiments (DOE) is proposed to design an optimum fixture layout in order to reduce the maximum elastic deformation of the workpiece caused by the clamping and machining forces acting on the workpiece while machining. Finite element method (FEM) is used to find out the maximum deformation of the workpiece for various fixture layouts. ANN is used as an optimization tool to find the optimal location of the locators and clamps. To train the ANN, sufficient sets of input and output are fed to the ANN system. The input includes the position of the locators and clamps. The output includes the maximum deformation of the workpiece for the corresponding fixture layout under the machining condition. In the testing phase, the ANN results are compared with the FEM results. After the testing process, the trained ANN is used to predict the maximum deformation for the possible fixture layouts. DOE is introduced as another optimization tool to find the solution region for all design variables to minimum deformation of the work piece. The maximum deformations of all possible fixture layouts within the solution region are predicted by ANN. Finally, the layout which shows the minimum deformation is selected as optimal fixture layout. 相似文献
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汽车覆盖件模具的高速加工具有特征型面形状复杂、材料硬度大、结构尺寸大、表面精度要求高等特点,在高速切削加工过程中,属于难加工产品。残余应力的存在促使疲劳裂纹形成与扩展、促进腐蚀、促进模具的关键型面变形,因此汽车覆盖件尺寸的稳定性和加工质量与其密切相关。本文在数值模拟思想的指导下,利用有限元解法,研究了高速铣削加工表面的残余应力对加工变形的影响,给出了预测残余应力数值的解析模型,具有重要的理论及现实意义。 相似文献
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X. Cerutti K. Mocellin 《The International Journal of Advanced Manufacturing Technology》2016,82(1-4):489-499
The manufacturing of aluminium alloy structural aerospace parts involves multiple steps, the principal ones being the forming (rolling, forging etc.), the heat treatments and the machining. During this last step, the final geometry of the part is obtained. Before machining, the workpiece has therefore undergone several manufacturing steps resulting in unequal plastic deformation and metallurgical changes which are both sources of residual stresses. On large and complex aluminium alloy aeronautical parts, up to 90 % of the initial workpiece volume can be removed by machining. During machining, the mechanical equilibrium of the part is in constant evolution due to the redistribution of the initial residual stresses.The residual stress redistribution is the main cause of workpiece deflections during machining as well as of post-machining distortion (after unclamping). Both can lead to the non-conformity of the part with the geometrical and dimensional tolerance specifications and therefore to a rejection of the part or to additional conforming steps. In order to improve the machining accuracy and the robustness of the process, the effect of the residual stresses has to be considered for the definition of the machining process plan. In this paper, a specific numerical tool [2] allowing to predict workpiece deflections during machining and post-machining distortion is used to study the influence of the machining sequence on the machining quality in taking into consideration the initial residual stresses. A first machining process plan defined as the reference case is simulated. Simulation results are then compared with experimental ones showing the feasibility to use the developed tool to predict the machining quality depending on the initial residual stresses, the fixture layout and the machining sequence. Using the computational tool, a method to optimise the machining quality depending on the initial workpiece and on the machining sequence is presented. A machining process plan allowing to respect the tolerance specifications is then defined. This demonstrates the feasibility to adapt and to optimise the machining process plan to ensure conformity of the part with the tolerance specifications. 相似文献