【作者】 赖周艺；

【导师】 夏琴香；

【作者基本信息】 华南理工大学 ， 机械制造及其自动化， 2012， 博士

【摘要】 旋压是现代先进制造技术的重要组成部分，是薄壁回转体零件加工中需要优先考虑的一种成形工艺。非圆横截面空心零件旋压（简称非圆旋压）是旋压技术的最新突破，是国际塑性加工领域前沿研究的热点之一。近年来国内外的研究已初步证明了非圆旋压的可行性，并发现非圆旋压在壁厚分布、旋压力变化等方面具有与常规旋压不同的特点，但具体成因的解析还有待非圆旋压成形机理的深入研究。非圆旋压零件横截面的变化改变了传统圆形横截面空心零件旋压成形过程中旋轮的运动状态，使其径向运动由静态（或准静态）变为动态，加上非圆横截面空心零件自身形状复杂程度的增加，使得非圆旋压成形机理更为复杂。本文在国家自然科学基金项目“非圆横截面空心零件旋压成形方法及变形机理研究”（课题编号：50775076）的资助下，以圆形、圆弧形和直边形等不同类型横截面空心零件为研究对象，采用最广泛应用的平板坯料普通旋压成形方式，综合采用理论分析、有限元数值模拟和实验研究等手段，深入地研究了非圆横截面空心零件旋压成形机理。对非圆横截面空心零件旋压进行了分类；指出了非圆旋压旋轮运动特征是“旋压成形过程中，旋轮在绕工件转过的一周范围内，成形的零件外轮廓至芯模转动中心的距离存在反复变化”；对非圆横截面空心零件旋压成形过程变形特点进行了理论研究，提出采用相对高度和相对圆角半径分析非圆横截面空心零件旋压变形程度。基于图解分析法，获得了旋轮运动特点及其对旋压成形速度、接触面积等的影响，全面揭示了非圆旋压成形过程中旋轮与坯料接触区位置的变化特点——接触区不仅由于旋轮的轴向进给而轴向移动，而且由于非圆横截面形状的变化而径向、轴向和周向移动；在此基础上建立了非圆旋压旋轮接触面积计算方法和旋轮径向进给运动轨迹计算方法。采用软件MSC.ADAMS对非圆旋压成形过程旋轮的运动进行了研究，并对基于图解分析法建立的非圆旋压成形过程旋轮运动轨迹计算结果进行了验证，结果表明计算结果可靠。分析了非圆旋压涉及的大变形弹塑性有限元法的基本理论，对坯料设计、模型离散、旋轮运动控制、并行运算等有限元数值模拟关键技术进行了研究，开发了面向单机多核并行运算的旋轮运动控制子程序，建立了基于MSC.MARC软件的非圆旋压三维弹塑性有限元数值模拟模型。通过改变模型离散方法和运动边界条件设置及采用并行运算有效提高了非圆旋压成形数值模拟效率。研究表明，采用坯料静止的运动边界条件和多核并行运算可在不降低模拟精度的前提下使非圆旋压有限元数值模拟时间减少76.97%。以三维弹塑性数值模拟为分析手段，系统研究了圆形、圆弧形和直边形等不同类型横截面空心零件旋压成形过程，比较了其变形方式、等效应力应变分布、应变状态、壁厚分布及回弹情况的异同，研究了非圆零件几何参数（偏心距、相对高度和相对圆角半径等）的影响。以非圆特征最为明显的三边形横截面空心零件为例，研究了旋压成形过程中旋压力的变化规律与影响因素。以三直边圆角形横截面空心零件为例，结合正交试验设计，研究了主要工艺参数（旋轮直径、旋轮圆角半径、相对间隙、主轴转速和旋轮进给比等）对成形精度（壁厚减薄和回弹等）的影响。研制了非圆旋压工装，并对三边形横截面空心零件旋压成形进行了实验研究，成功试制出横截面最复杂的非圆旋压件——三直边圆角形横截面空心零件。利用应变网格实验获得了三边圆弧形横截面空心零件三向应变和等效应变分布规律；通过电测法实测得到旋压过程中旋压力的变化规律及工艺参数的影响；并运用工艺实验对理论分析结果及数值模拟结果进行了全面验证。从成形过程、成形件高度、壁厚减薄和旋压力等角度来看，本文所建的数值模拟模型是合理可靠的；实验所得的应变分布、应变状态、旋压力、工艺参数对成形精度的影响规律等与数值模拟结果吻合良好，数值模拟结果可靠。更多还原

【Abstract】 Metal spinning is an important integral part of modern advanced manufacturingtechnologies, and is considered as the preferred forming process for the production ofthin-walled revolution parts. Non-circular spinning is the latest breakthrough of metalspinning technology, which has became the forefront in the international research field ofplasticity engineering. In recent years, researchers in China and abroad have preliminaryproved the feasibility of non-circular spinning and find that there are many differencesbetween non-circular spinning and traditional spinning on the aspects such as wall thicknessdistribution, spinning force variation, etc. The causes of the above phenomena can’t be founduntil in-depth research on the mechanism of non-circular spinning was done. The variation ofthe cross-section of the non-circular spinning part changes the motion status of the roller, andmakes its radial movement change from static or quasi-static during traditional spinning todynamic. Coupled with a more complex shape of the non-circular cross-section, themechanism of non-circular spinning is extreme complex.The research of this thesis was financially supported by National Natural ScienceFoundation of China (Subject title: Research on spinning method and deformation mechanismof hollow parts with non-circular cross-section; Subject No.:50775076). The hollow partswith circular, arc-type or straight-edge-type cross-section were selected as the study objects,and the most widely used spinning process: conventional spinning process with a flat sheetmetal blank was adopted, and combined with the theoretical analysis, numerical simulationand experimental investigation, in-depth research on the spinning mechanism of the hollowparts with non-circular cross-section was carried out.The classification of spinning of the hollow parts with non-circular cross-section hasbeen carried out, and the motion characteristic of the roller during non-circular spinning hasbeen revealed, which is that the distance from the outer contour of the part to the rotationalcenter varies repeatedly during every rotation of the mandrel. The deformation characteristicduring non-circular spinning was studied, and a deformation degree analysis method using therelative height and relative radius was put forward. By graphical analysis method, the motioncharacteristic of the roller and its effects on the forming speed, contact area and so on werestudied, and the variation characteristic of the contact position between the roller and blankwas revealed comprehensively, which does not only move along the axial direction for theroller’s axial feeding, but also moves along the radial, axial and circumferential directions forthe variation of the non-circular cross-section. Based on the above variation characteristic, the calculating methods for the contact area and the roller radial feed track were established. Thesoftware MSC.ADAMS was used to analyze the motion of the roller during non-circularspinning, and the calculated result of the roller radial feed track by graphical analysis methodwas verified. The result shows that the calculated result is reliable.The basic theory of finite element method (FEM) of the large elastic-plastic deformationwas introduced. The key techniques of the numerical simulation, including the blank design,meshing, motion control of the roller, parallel simulation and so on, were researched. Asubroutine for the motion control of the roller during multi-core parallel simulation wasdeveloped. The3D elastic-plastic FE numerical simulation model for the non-circularspinning was established using the software MSC.MARC. By changing the meshing method,boundary condition and using parallel simulation, the numerical simulation efficiency wasimproved effectively. The research results show that by using the stationary boundarycondition of the blank and multi-core parallel simulation, the simulation time can be reducedby76.97%while the simulation accuracy unaffected.With3D elastic-plastic numerical simulation, systematic studies on the spinning processof the hollow parts with circular, arc-type or straight-edge-type cross-section were carried out,and an analysis of the similarities and differences of the deformation model, equivalent stressand strain distributions, strain state, wall thickness distribution and springback was done. Theeffects of the geometry parameters of the non-circular part, such as the offset distance, relativeheight and relative radius, were revealed. Taking the hollow part with three straight-edgeround-corner cross-section as the study object and combining with the orthogonalexperimental design, the effects of the main process parameters, such as the roller diameter,roller nose radius, relative clearance between the roller and mandrel, spindle rotational speedand roller feed rate, on the forming accuracy (the wall thinning, springback, eta) wereobtained.A device for the non-circular spinning was designed and manufactured. And a series ofexperiments was carried out. The hollow part with three straight-edge round-cornercross-section was manufactured by spinning process successful, which is one of the mostcomplex spun parts recently. By the grid experiment, the distributions of the strain andequivalent strain of the hollow part with triangular arc-type cross-section were obtained. Bythe electrical measuring method, the variation of the spinning force and the influence of theprocess parameters on the spinning force were investigated. The theoretical results andnumerical simulation results were fully verified by experiments. Judged by the formingprocess, height of spun part, wall thinning and spinning force, the simulation model established in this thesis is high reliable. The experimental results were used to compare withthe simulation results on the aspects of the strain distribution, strain state, spinning force andthe effect of process parameters on the forming accuracy, and good agreements are observed.更多还原