基于有限元模拟的铜包铝线拉拔参数优化

为研究拉拔参数对铜包铝线质量的影响,运用有限元方法对金刚石涂层拉拔模具拉拔铜包铝线的过程进行了模拟仿真,研究了拉拔过程中模具的应力分布情况,分析了压缩率对铜包铝线残余应力分布均匀性的影响规律。利用正交实验法研究了拉拔参数(工作锥半角α,定径带长度L,过渡圆弧半径R,压缩率β)对铜包铝线尺寸精度和残余应力分布均匀性的影响,获得了最佳拉拔参数(α=6°,L=4.5 mm,R=3 mm,β=1.82%)和各因素对分析指标的影响规律。并在此基础上对优化方案进行了模拟,结果证明了正交实验对拉拔参数优化的有效性,对金刚石涂层拉拔模具的设计及高质量铜包铝线的拉制有重要的指导意义。     

高强度钢制异形件制坯工艺优化研究

利用有限元数值模拟软件Deform-3D,对锁闩的不同制胚方案进行模拟,对比分析模拟结果,优化方案。进一步对预锻模具进行应力分析,根据模具应力分析结果,进一步验证优化方案,以改善模具结构,提高模具寿命。结果表明:预锻模具应力集中主要分布在模腔台阶处和模具中间区域,当坯料角度α=60°时,能有效地减少预锻成形的单位应力,降低挤压力,提高模具寿命。     

冷拔量参数对冷拔直线导轨加工质量的影响分析

为了研究道次间的冷拔量参数对冷拔直线导轨加工质量的影响,以第二道次与第三道次冷拔模具孔型间的冷拔量为因素,以滚动直线导轨左侧沟槽残余应力最大值、导轨底部沟槽残余应力最大值、导轨直线度作为冷拔直线导轨加工质量的评价指标,进行正交试验。在研究中,确定了坯料和冷拔道次,选取了冷拔量,并进行了第三次冷拔仿真。通过试验确定了最优的冷拔量参数组合,可以为冷拔异型钢模具孔型设计提供技术参考。     

外星轮热挤压预成形多目标优化设计

针对外星轮热挤压成形性能波动,模具杆部过渡圆角区磨损严重的问题,对关键模具结构和挤压工艺参数开展优化研究。基于有限元数值模拟仿真,结合析因试验分析首先得到影响磨损和填充的关键参数及其影响方向。随后对核心参数构造代理模型替代有限元机理模型,用于磨损和填充性能的数值预测。并使用线性加权和法将所得近似模型转化为单目标函数,耦合遗传算法进行全局寻优。计算发现,当入口斜度y=30°,根部圆角a=18.6 mm,杆部圆角b=5 mm,模具硬度HRC60,摩擦因数m=0.1,挤压速度v=10 mm/s,模具预热温度T=300℃,坯料初始温度t=1 180℃时,在保证锻件填充完全的前提下可获得模具最大磨损量的显著降低,模具寿命较初始提高约2 100件。最后通过仿真和生产试验验证了优化结果的正确性。     

刨煤机刨刀多目标参数优化设计与试验对比研究

对刨刀刨削煤岩受力模型进行分析,获得焊缝最大应力与刨削阻力的计算公式,并通过改进非支配排序进化遗传算法(NSGA-Ⅱ),以焊缝应力最小和刨削能耗最小为目标,对刨刀结构参数进行多目标优化,获得一组刨刀理想结构参数为:前角γ=14.005°,后角α=9.61°,刀宽bp=28.11 mm,刀间距t=80.53 mm。通过刨削对比试验对优化结果进行验证,试验结果表明,优化后的刨刀刨削煤岩阻力载荷波动情况有所好转,受力状态及应力集中状态发生改善,力学性能获得提升。此外,通过绘制刨削速度与刨削阻力均值关系曲线可知,刨削速度的改变对阻力均值影响较小。     

传动轴万向节叉精密成形过程有限元模拟

采用刚粘塑性有限元法对传动轴万向节叉精密成形过程进行了数值模拟分析,得出了成形过程中的挤压力、速度、应力、应变及温度场的变化规律,较好地预测了成形过程中可能产生的缺陷.本文研究结果有助于对传动轴万向节叉成形工艺及模具结构进行优化设计.     

基于正交试验薄壁件注塑分析及优化设计

利用Moldflow软件对薄壁件的注塑成型过程进行了模拟分析,设计了两种注塑成型方案,并进行了模流分析和翘曲情况分析,选择出最优的注塑方案。使用正交试验法分析翘曲变形的影响因素,寻找最优参数使薄壁件的翘曲变形最小。分析结果表明:薄壁件最优的注塑方案为两个浇口注塑方案;各因素对翘曲变化的影响程度为保压压力保压时间熔体温度模具温度;最优工艺参数为A2B1C2D2,即熔体温度280℃、模具温度60℃、保压时间10s、保压压力140MPa。最大翘曲变化量由优化前的2.781mm降到优化后的1.661mm。     

汽车天窗导轨悬臂型材挤压模具设计及工艺参数优化

采用分流组合模具结构设计方法改进设计了某汽车天窗导轨悬臂实心型材传统的挤压模具,利用Hyper Xtrude软件,分析了挤压模具的应力状态及偏移量。以提高模具强度为指标,设计了挤压工艺参数正交试验的数值模拟方案,对试验结果进行了极差分析,得出了挤压工艺参数的最优组合。试验结果显示各挤压工艺参数与模具应力之间呈较强的线性关系,由此以正交试验数据为样本,建立了四元线性回归模型,并通过对任意组合的挤压工艺参数进行数值模拟测试,验证了回归方程的可靠性,模型为挤压工艺参数的选择提供了参考。     

基于DEFORM-3D容差值对模具应力分析的影响

容差值是模具应力分析的一个重要参数,决定着模具应力分析数值模拟的精确程度,利用模拟软件DEFORM-3D对不同容差值下冷挤压模具进行的模具应力分析,得到模具应力分布规律,并通过对比分析,阐述容差值对模具应力分析的影响,确定冷挤压模具应力分析数值模拟合理的容差值选取规律。结果表明,随着容差值的增大,应力分析的精度与计算时间也随之增大,当容差值增大到一定值后,分析精度随之平稳,不再随之变化。分析表明,较为合理的容差值应介于模具网格划分的最大/最小尺寸值之间,此时应力分析兼具精度与效率。     

基于响应面法传动直轴疲劳寿命优化

针对传动轴提前发生疲劳失效问题,开展对应力状态及寿命的研究,通过对实测载荷的分析,得出传动轴提前发生疲劳失效的原因是左右两侧花键输出载荷不一致,利用有限元软件建立传动轴有限元模型,得到传动轴右侧齿根处应力最大,是传动轴的薄弱部位。采用响应面法和遗传算法对传动轴的结构参数(齿根圆角、花键过渡圆弧及光轴圆弧槽深)进行优化,优化后的传动轴齿根薄弱部位应力降低了28.3%,传动轴的疲劳寿命提升了五倍,可靠度更高。最后以比例缩小试样进行疲劳试验,试验结果表明传动轴寿命提升到原来的两倍。通过试验验证了优化方法的有效性,方法对之后轴类零部件优化有一定的参考意义。     

A knowledge-based parametric design system for drawing dies

The design of drawing dies is a very complex and knowledge-intensive process. This paper describes a knowledge-based parametric design system for drawing dies which requires only a minimum set of parameters to be set before it is able to complete the design of the main components of a die, such as upper dies, lower dies, and blank holders. This minimum set of parameters includes blank sizes, die faces, punch open lines, drawing strokes, and press data. This design system implemented on top of the Pro/E CAD software consists of a drawing die knowledge base, a subcomponent inferencer, a dimension calculator, a subcomponent generator, a system coordinator, and a user interface. We use the design of drawing dies for inner wheel house as a concrete example to show that our system can greatly improve the design quality while reducing the development time and cost.     

Application of the fuzzy-based Taguchi method for the structural design of drawing dies

In the sheet metal stamping process for automobiles, the drawing process requires the greatest stamping force, and thus the structure of the drawing dies is the thickest and heaviest among all stamping dies. This study describes how the fuzzy-based Taguchi method can be applied to explore multi-objective optimization in the structural design of drawing dies. Using the lower die of the drawing die for the engine hood??s outer panel as an example, the current study explores four parameters that primarily influence the strength and weight of their structure, namely the rib thickness of the punch open line, the pitch of the structure rib, the thickness of the punch surface, and the thickness of the structure rib. Firstly, CATIA software is used to construct a geometric model of the drawing die, and a structural analysis of the model is performed. Next, within the constraints of allowable stress, allowable deflection and allowable size and pitch of the rib, etc., we apply the Taguchi method to evaluate the allowable characteristics of the two objective functions, namely the deflection and weight of the lower die. Then, through factor effect analysis and analysis of variance, the influences of the design parameters upon the objective functions are determined. Next, a fuzzy logic inference is utilized to obtain the measuring index which results in the optimization of the multiple performance characteristics. Finally, by comparing the results from the maximized design and the results from the original design, it is shown that the deflection of the lower die structure is only increased by 0.0038?mm (8.1%), but its weight can be greatly decreased by 506?kg (12%).     

聚晶金刚石拉丝模拉拔过程的计算仿真

采用ABAQUS有限元分析软件对太阳能硅片切割丝拉制用聚晶金刚石拉丝模拉拔过程进行了运动仿真,根据拉丝模结构对称性的特点,选择1/2模型进行分析,并对模套的上下表面施加全约束来模拟拉丝的实际状况。通过计算获得了切割丝轴向应力分布图及所受最大轴向拉应力随时间变化曲线和聚晶金刚石拉丝模等效应力分布图及所受的等效应力曲线,并进行了分析总结。最后得出在拉拔加工过程中聚晶金刚石模芯所受的最大等效应力为6474MPa,从而为拉丝模模芯材料的选择提供了一定的理论依据。     

高压涡轮轴安装边倒角低应力设计方法

航空发动机涡轮鼓筒轴承受着复杂的外载荷,在涡轮轴的安装边倒角处会产生应力集中,影响涡轮轴的整体寿命和性能。本文研究在扭矩、轴向力、离心力以及热应力4个载荷作用下涡轮轴安装边附近倒圆角的应力场分布,设计了单圆弧倒角方案、双圆弧倒角方案,并运用ANSYS Workbench软件对双圆弧设计方案进行优化。通过比较三种结构的应力场分布,得到涡轮轴安装边倒角的低应力设计方案。本文得到的最优双圆弧设计方案相比单圆弧设计方案,倒角处的最大等效应力降低了13.97%。     

轴类零件的外轮廓识别方法

提出了识别轴类零件外轮廓的逆时钟最小夹角法,讨论了五种特殊角度计算及多对象相切情况的处理方法,确定了轮廓点的搜索原则和中心线的处理方法.在AUTOCAD2006环境下,以ObjectArx为开发工具,实现了文中提出的原理和方法,以某典型轴类零件图为例,识别效果好.     

拉深、翻边、切边和冲底孔复合模具设计

根据零件的结构特点及技术要求,围绕如何降低生产成本、提高工作效率和简化模具结构,通过比较多种工艺方案,采用线切割进行剪料,以定位板进行定位,确定了由拉深、翻边、切边和冲底孔等工序组成的冲压工艺方案,并对其所有工序进行了工艺计算;同时,设计了1副拉深、翻边、切边和冲底孔复合模具。结果表明,采用此工艺方案和模具结构显著提高了盒形零件的生产效率和产品质量。     

Some numerical slipline field solutions for drawing through circular dies

A method is presented for the generation of slipline fields and their hodographs for the problem of plane strain drawing a rigid, perfectly plastic (rpp) material through frictionless circular dies. An optimization scheme is given, using a readily available multivariable optimization routine, which will reliably adjust the shape of an assumed slipline to ensure hodograph convergence. A number of programme runs using different geometries show some interesting oscillatory variations in the computed stress distributions along the die surface and across the exit slipline.     

Round-to-square section drawing through flat idle rolls

Cold drawn metal bars of regular polygonal section are industrially produced by direct drawing from round stock using either a round-to-polygonal section converging die or a drawing head comprising an adjustable set of symmetrically arranged flat idle rolls. In the present work a solution is obtained to determine the roll load and drawing force for steady state direct cold drawing of square section from round stock through flat idle rolls. The results obtained have shown that the drawing force in a case of fair lubrication condition amounts to about 40% of that required for drawing through converging dies, which allows using a drawbench of lower load capacity. The drawing stress is highly influenced by the friction conditions at the roll surface and to a lesser extent by the area reduction ratio and roll diameter, indicating the need for good quality finish and adequate lubrication for the rolls contact surface. The ratio of the drawing stress to the roll mean pressure is independent of friction and increases almost linearly with the increase of area reduction ratio.     

带法兰阶梯轴冷镦挤复合成形工艺研究

针对带法兰盘阶梯轴的结构特点,提出了镦挤复合成形工艺方案,并分别研究了在冷镦挤条件下,不同直径坯料对成形过程的影响.采用有限元模拟软件对带法兰盘阶梯轴的成形过程进行了数值模拟,比较分析了不同坯料尺寸对变形过程中金属流动、应变以及载荷曲线等的影响.试验结果表明,采用冷镦挤复合成形工艺成形带法兰盘阶梯轴,可以获得高质量和高精度的锻件,实现近净成形.