基于环向应变量优化的无芯模旋压变参数成形方法研究

发布时间：2018-05-30 01:21

本文选题：无芯模旋压 + 变参数成形　；参考：《浙江大学》2017年博士论文

【摘要】：旋压成形技术因设备简单、变形力小、改善材料性能及无屑成形等优势,已广泛应用于机械加工领域。但特定芯模的使用限制旋压成形的柔性,阻碍旋压技术的进一步发展。无芯模旋压采用通用芯模增强旋压成形的柔性,是一种颇具潜力的新型金属成形技术,具有广阔的研究及应用前景。鉴于旋压成形工艺参数对不同质量参数的影响通常呈现矛盾趋势,采用恒定成形工艺参数难以实现无芯模旋压参数化、智能化和精密化的发展要求。为解决上述问题,本文建立了基于环向应变量的旋压成形量参数化表征模型及旋轮轨迹曲线参数化模型,为构建工艺参数-成形质量影响模型确立奠定基础;构建坯料成形过程显式分析与坯料回弹过程隐式分析相结合的有限元分析模型,获取无芯模旋压坯料自由变形机理;基于自主研发的复合式板料旋压机建设无芯模旋压成形试验平台及成形件质量参数测量方法。对变参数旋压方法的机理进行分析,形成关键旋压工艺参数的调整思路。提出了基于道次间环向应变量优化分配的无芯模旋压变轨迹形状设计方法。基于道次间环向应变量优化分配,获取道次间距优化设计方案,为后续研究奠定工艺方案基础。比较了四种轨迹形状设计和三种道次间距设计方法,进而提出轨迹形状设计中利于形状误差抑制的“几何相似性原则”及利于壁厚保持的“小曲率原则”;道次间距设计中利于形状误差抑制的“环向应变量趋大原则”及利于壁厚保持的“环向应变量均匀分配原则”。在此基础上根据终道次优先的改进思路提出变轨迹综合优化设计方案。提出了基于道次间/内环向应变量逐层分解的无芯模旋压变进给比旋压方法.将总环向应变量进行道次间分解,根据各道次环向应变量进行道次间成形时间优化分配,提出有利于提高形状精度的“环向应变匀速分解原则”及“终道次充分成形原则”,通过与道次间环向应变量相联系的道次间变进给方法实现坯料整体匀速变形。将终道次内环向应变量进行分解,根据局部环向应变进行道次内成形时间优化分配,并提出有利于抑制形状误差的“环向应变趋大充分成形原则”。提出了基于环向应变量-形状误差分治的无芯模旋压变轨迹形状修正方法。通过动态-静态分步求解方法获取回弹及过成形误差的形成机理与分布特征,从而建立二者与环向应变量的影响模型。提出利于回弹误差控制的“环向应变均匀分布原则”及利于过成形误差控制的“环向应变均匀变化原则”。通过无芯模旋压变轨迹形状修正方法实现回弹和过成形误差的分离及基于形状误差数据的一次修正,并在此基础上根据形状误差-环向应变量关系模型实现“继发性”形状误差的预补偿。为验证本文所提出变参数成形方法的有效性,将变轨迹设计、变进给比方法和变轨迹形状修正三项变参数关键技术分别应用于三个罩壳类回转件产品的旋压过程中,分别改善了成形件开裂失效、起皱失效及形状精度,从而验证了无芯模旋压变参数成形方法的实际效果。
[Abstract]:Because of the advantages of simple equipment, small deformation force, improving material performance and non chip forming, spinning technology has been widely used in the field of mechanical processing. However, the use of specific core mould limits the flexibility of spinning forming, which hinders the further development of spinning technology. The new metal forming technology has a broad prospect of research and application. In view of the contradictory tendency of the technological parameters of the spinning process to different quality parameters, it is difficult to realize the development requirements of the non core mould spinning parameterization, intellectualization and precision with the constant forming process parameters. The parameterized characterization model and the parameterized model of the rotary wheel trajectory curve are established to establish the foundation for the establishment of the process parameter forming quality influence model, and the finite element analysis model combining the explicit analysis of blank forming process with the implicit analysis of the billet springback process is constructed to obtain the free deformation of the non core mould spinning blank. Mechanism, based on the independent research and development of the compound plate spinning machine, the test platform of the core free mould spinning forming and the measurement method of the quality parameters of the forming parts are constructed. The mechanism of the variable parameter spinning method is analyzed, and the adjustment idea of the key spinning process parameters is formed. Shape design method. Based on the optimal allocation of the intersecondary ring direction variables, the optimal design scheme of the channel spacing is obtained, which lays the foundation for the process plan for the follow-up research. Four kinds of trajectory shape design and three ways of the design of the channel spacing are compared, and the "geometric similarity principle" which is beneficial to the shape error suppression in the trajectory shape design is put forward and the advantage of the "geometric similarity" is put forward. "The principle of small curvature" for the wall thickness, the "principle of the ring direction variable" which is beneficial to the shape error suppression and the principle of "uniform distribution of the circumferential stress" for the wall thickness. On this basis, a comprehensive optimization design scheme for the variable trajectory is proposed based on the improvement thought of the final channel priority. The inter / inner ring is decomposed to the corresponding variable by layer by layer. The total ring is decomposed to the corresponding variable, and the distribution of the forming time is optimized according to the corresponding variables. The principle of "circumferential strain uniform resolution principle" and the "final full forming principle" are put forward to improve the shape precision. The integral uniform deformation of the billet is realized by the method of intercourse variable feed link with the cross link to the channel. The final inner ring is decomposed to the corresponding variable. According to the local circumferential strain, the distribution of the forming time in the channel is optimized, and the principle of "the full forming of the circumferential strain" is put forward to restrain the shape error. Based on the circumferential strain and shape error dividing method, the formation mechanism and distribution characteristics of the springback and over forming error are obtained by the dynamic and static method, and the influence model of the two and the circumferential variables is established, and the "uniform distribution original of the loop strain" is proposed for the control of the return elastic error. The principle of "uniform change of circumferential strain", which is favorable for over forming error control, is used to realize the separation of springback and over forming errors and a correction based on shape error data through the shape correction method of the non core model spinning variable trajectory shape, and on this basis, the "secondary" shape is realized on the basis of the shape error loop strain relation model. To verify the error precompensation, in order to verify the validity of the variable parameter forming method proposed in this paper, the key techniques of variable trajectory design, variable feed ratio and variable trajectory shape correction three variable parameters are applied to the spinning process of three shell and shell revolving parts respectively, and the cracking failure, wrinkling failure and shape accuracy of the formed parts are improved, respectively. The actual effect of the variable parameter forming method of spinning without core mold is verified.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TG306

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