轴承环毛坯塔锻工艺的编制

详细阐述了轴承环毛坯塔锻成形工艺的编制方法;介绍了塔锻件公差、余量的选取,锻件图的制定、塔锻件、预成形件、镦粗件和坯料形状和尺寸的设计和计算.     

基于SIMA法的铝合金复杂构件触变锻造成形技术

采用半固态触变锻造技术成形铝合金构件,容易实现轻量化、低成本、短流程制造,因此在汽车、航空航天等领域应用广泛,但是对于高强铝合金复杂形状构件触变锻造存在半固态坯料制坯工序复杂、制件固液偏析严重和力学性能较弱等问题。基于SIMA制坯方法,提出了分级热处理、快速感应重熔和梯度等温处理等重熔工艺以及触变-塑变复合成形等新成形技术,优化了变形铝合金二次重熔半固态组织调控和触变锻造技术,获得了良好的半固态球晶组织并成形出合格的制件,最后提出了铝合金触变锻造成形中仍需解决的问题和发展方向。     

RR装置上曲轴镦锻工艺优化研究

以16V280曲轴为试验对象,通过对RR装置的镦锻工艺、曲柄臂锻件形状和锻造模具结构优化,研究了采用小直径坯料的情况下16V280曲轴曲柄臂的成形情况。试验结果显示,优化后的预上弯镦锻工艺,能保证在RR装置上采用小直径坯料镦锻曲轴可行。     

金属材料铸锻复合成形技术的研究进展

铸造可以成形形状复杂的零件,但铸件的力学性能普遍较低;锻造可以成形力学性能较高的零件,但锻件的形状复杂度受到很大的限制。铸锻复合成形技术将铸造和锻造相结合,取长补短,可成形高性能复杂形状零部件。介绍了几种典型铸锻复合成形工艺,包括铸锻联合工艺、双重挤压铸造、铸挤锻复合工艺、压铸锻造双控技术、铸锻一体化成形技术等。重点介绍了铸锻一体化成形技术的研究进展,并对铸锻复合成形技术的前景进行了展望。     

Al-Cu-Mg-Zn超硬铝合金盘类构件塑性变形性能及锻造成形工艺的研究

目的 为了有效改善Al-Cu-Mg-Zn超硬铝合金盘类锻造构件成形精度和力学性能.方法 通过对代号7A04的Al-Cu-Mg-Zn系超硬铝合金进行热压缩实验,分析其流变行为;通过应力-应变数据,建立本构方程及热加工图.将构建的7A04超硬铝合金材料模型导入有限元分析软件中,同时对锻件成形过程进行仿真模拟并优化.结果 获得了基于Arrhenius模型的流变应力本构方程;确定了7A04超硬铝合金最适宜的加工区域,为后续的仿真模拟提供指导;基于7A04超硬铝合金盘类构件锻造成形有限元仿真模拟分析结果,获得了变形均匀锻件的最优方案.结论 通过全尺寸锻造生产实验对模拟分析结果进行验证,获得了变形均匀且无锻造工艺缺陷的7A04超硬铝合金盘类构件.     

Ti–6Al–4V钛合金筋板类吊挂锻造成形工艺优化及模具磨损研究

目的 改善Ti–6Al–4V筋板类吊挂锻件成形缺陷,降低模具磨损。方法 通过对原始工艺中存在的折叠、充填不满等缺陷进行分析,揭示局部飞边高度对锻件充填的影响,进而优化终锻模具局部飞边高度;通过增加预锻件筋条等几何特征,对预锻模具结构进行优化设计,并分析塑性变形时筋条区域金属材料的流动情况。结合BP神经网络技术,分析锻造工艺参数对终锻模具磨损的影响,并对工艺参数组合进行优化设计。结果 基于局部飞边高度对锻件充填效果的影响规律,确定最佳局部飞边高度为4mm;通过增加预锻筋条优化预锻件结构,从而有效避免折叠缺陷;将BP神经网络技术与数值模拟结合,得到了最优工艺参数组合,有效降低了锻造模具的磨损量。结论 通过实际锻造生产试验对模拟分析结果进行了验证,固化了最佳模具结构与工艺参数组合,获得了变形均匀且无工艺缺陷的钛合金发动机吊挂锻件。     

阀盖模锻成形模拟分析与试验验证

目的 某型号不锈钢阀盖是一种典型的长肋条内空型零件,在模锻制造过程中,阀盖锻件容易出现不同程度的折叠和裂纹缺陷,亟需改进成形工艺以提升合格率.方法 采用有限元方法分析坯料在制坯/预锻/终锻全流程的金属流动规律和终锻件成形质量,得到最佳成形工艺方案.结果 方坯在后续成形时易产生横向流动,且局部充型不饱满;六边型坯在预成形和终成形时流动均匀、横向流动小,且有效抑制了充型不饱满缺陷;预制坯在过渡区长度过短,产生了折叠缺陷;采用六边形坯料和增加过渡区长度可以获得无缺陷阀体锻件.结论 采用新工艺制备的阀盖锻件合格率达到了100％,通过全流程工艺分析,能够得到金属流线规律,进而优化模锻成形方案,改善成形质量.     

基于类等势场和响应面法的复杂锻件预成形优化设计

为实现复杂锻件的预成形设计,以连杆的热锻预成形设计为研究对象,建立基于类等势场和响应面分析的三维复杂锻件的预成形设计方法。在分析毛坯与终锻件间等势场分布规律与特点的基础上,采用逆向拟合法提取等势面及线面光顺处理,实现等势面的高效精确重构。针对长轴类锻件的预成形设计要求,提出沿零件的长、宽、高分别设置合理的缩放因子的非均匀缩放方法。实现了预成形件材料分布的合理调控,获得了优化的预锻件和辊锻毛坯,最终获得了充填完整、无任何成形缺陷且飞边小的连杆终锻件。数值模拟结果表明,所建立的方法能较好实现复杂锻件的预成形优化设计。     

连杆断裂失效分析及锻造折叠缺陷控制研究

目的 确定连杆断裂失效模式、机理和原因,找到有效预防连杆锻造缺陷的措施。方法 针对连杆断裂失效问题,在对连杆合格件和故障件进行符合性对比试验分析的基础上,对故障件进行断裂失效模式、机理和原因分析,并对连杆锻造折叠缺陷产生类型、机理、原因、条件和时段进行分析。结果 只有在连杆制坯坯料形状与尺寸不合理、制坯坯料在预锻模膛中位置不合理、预锻形状与尺寸不合理、预锻成形打击力或变形速度不合理、终锻形状与尺寸不合理、锻模导向功能失效等多种极端不利因素同时存在的条件下,才具有产生复合型锻造折叠缺陷的可能性。结论 通过连杆锻造过程控制和锻造首锻控制,可有效预防锻造折叠缺陷产生,满足锻件高优质性、高可靠性和高有效性要求。     

高功率密度发动机连杆热模锻工艺模拟与优化

目的研究某高功率密度发动机连杆的锻造工艺。方法首先采用传统设计方法设计了连杆模锻工艺,再通过有限元模拟分析优化工艺。结果根据有限元模型,分析了传统设计方法下的毛坯充型效果,直观地再现了终锻成形过程中的坯料外形演变和容易出现成形缺陷,在此基础上,优化了毛坯尺寸,满足了终锻充型要求。结论通过工艺试验进一步验证了模拟结果,获得的锻件没有出现缺肉、折叠等缺陷,微观组织较均匀,能够满足技术要求。     

Optimal Preform die Design through Controlling Deformation Uniformity in Metal Forging

A finite element based sensitivity analysis method for preform die shape design in metal forging is developed.The optimization goal is to obtain more uniform deformation within the final forging by controlling the deformation uniformity.The objective function expressed by the effective strain is constructed.The sensitivity equations of the objective function,elemental volume,elemental effective strain rate and the elemental strain rate with respect to the design variables are constituted.The preform die shapes of an H-shaped forging process in axisymmetric deformation are designed using this method.     

ANALYSIS OF AXISYMMETRIC FORGING OF POROUS MATERIALS BY THE FINITE ELEMENT METHOD

Axisymmetric forging of powdered-metal preforms was analyzed by the finite element method neglecting the effect of temperature on deformation. A remeshing program based on the area-weighted-average technique was developed and tested by simulating forging of the flange-hub shape. Then the analysis was performed for forging of a pulley blank. The detailed deformation characteristics for the different preform shapes under the two frictional conditions were obtained. A comparison between the prediction and the experiment regarding proper preform design to forge defect-free pulley blank demonstrates that the finite element analysis is useful for further developments in preform design in powdered-metal forging.     

Microstructure optimization design methods of the forging process and applications

A microstructure optimization design method of the forging process is proposed. The optimization goal is the fine grain size and homogeneous grain distribution. The optimization object is the forging process parameters and the shape of the preform die. The grain size sub-objective function, the forgings shape sub-objective function and the whole objective function including the shape and the grain size are established, respectively. The detailed optimization steps are given. The microstructure optimization program is developed using the micro-genetic algorithm and the finite element method. Then, the upsetting process of the cylindrical billet is analyzed using a self-developed program. The forging parameters and the shape of preform die of the upsetting process are optimized respectively. The fine size and homogenous distribution of the grain can be achieved by controlling the shape of the preform die and improving the friction condition.     

Sensitivity Analysis Based Multiple Objective Preform Die Shape Optimal Design in Metal Forging

The multiple objective preform design optimization was put forward. The final forging＇s shape and deformation uniformity were considered in the multiple objective. The objective is to optimize the shape and the deformation uniformity of the final forging at the same time so that a more high integrate quality of the final forging can be obtained. The total objective was assembled by the shape and uniformity objective using the weight adding method. The preform die shape is presented by cubic B-spline curves. The control points of B-spline curves are used as the design variables. The forms of the total objective function, shape and uniformity sub-objective function are given. The sensitivities of the total objective function and the sub-objective functions with respect to the design variables are developed. Using this method, the preform die shape of an H-shaped forging process is optimally designed. The optimization results are very satisfactory.     

Shape optimization of preform tools in forging of aerofoil using a metamodel-assisted multi-island genetic algorithm

Preform design plays an important role in improving the material flow, mechanical properties and reducing defects for forgings with complex shapes. In this paper, a study on shape optimization of preform tools in forging of an airfoil is carried out based on a multi-island genetic algorithm combined with a metamodel technique. An optimal Latin hypercube sampling technique is employed for sampling with the expected coverage of parameter space. Finite element (FE) simulations of multistep forging processes are implemented to obtain the objective function values for evaluating the forging qualities. For facilitating the optimization process, a radial basis function surrogate model is established to predict the responses of the hot forging process to the variation of the preform tool shape. In consideration of the compromise between different optimal objectives, a set of Pareto-optimal solutions are identified by the suggested genetic algorithm to provide more selections. Finally, according to the proposed fitness function, the best solution of multi-objective optimization on the Pareto front is confirmed and the corresponding preform tool shape proves optimal performances with substantially improved forging qualities via FE validation.     

Sensitivity analysis and shape optimization for preform design in thermo‐mechanical coupled analysis

In complex forging processes, it is essential to find the optimal deformation path and the optimal preform shape that will lead to the desired final shape and service properties. A sensitivity analysis and optimization for preform billet shape in thermo‐mechanical coupled simulation is developed in this work. Non‐linear sensitivity analysis of temperatures, flow‐stresses, strains and strain‐rates are presented with respect to design variables. Both analytical and finite‐difference gradients are employed to validate the effectiveness of sensitivity analysis developed in this work. Numerous iterations of coupled thermo‐mechanical analysis are performed to determine an optimum preform shape based on a given criterion of minimizing the objective function on effective strain variance within the final forging. The design constraints are imposed on die underfill, material scrap, folding defects and temperatures. In addition, a method for material data processing is given in order to determine the flow stress and its derivatives. The shape optimization scheme is demonstrated with the preform designs of an axisymmetric disk and a plane strain problem. Copyright © 1999 John Wiley & Sons, Ltd.     

基于有限元灵敏度分析的预锻模具形状优化设计

在控制锻件几何形状的前提下 ,采用有限元灵敏度分析方法 ,对预锻模具形状进行优化设计 .针对下模速度为零时 ,速度灵敏度边界条件为零 ,其形状在优化迭代过程中得不到优化的情况 ,对速度灵敏度边界条件提出改进措施 ,使上下模具形状同时能够得到优化 .最后给出了优化设计实例 ,验证该方法的可靠性 .     

锻造过程中变形均匀性控制及模具优化设计

以直接设计预成形模具形状为目标 ,提出并建立了一种控制变形均匀性的灵敏度分析理论和模具形状优化设计方法 .以任意单元的等效应变与所有单元的平均等效应变的差值的平方和作为目标函数 ,B样条曲线表示模具形状 ,B样条曲线控制点坐标作为优化设计变量 ,优化设计的目标就是通过设计预成形模具形状使目标函数最小 ,即使整个工件的变形尽可能均匀 .给出了目标函数的表达形式 ,详细推导了目标函数、单元等效应变率和单元各应变率分量对优化设计变量的灵敏度 .并对圆柱体平面镦粗工艺进行预成形优化设计 ,给出了相应的优化设计结果 .     

基于目标应变分布的TC17合金双性能盘预成形形状优化设计

目的 研究TC17合金双性能盘目标应变分布下的预成形形状优化设计方法.方法 采用拉丁超立方试验设计方法对预成形形状设计变量抽样选取样本点,并通过Deform有限元数值模拟获得样本设计变量下的局部应变分布.以局部应变分布与目标应变分布之间的方差最小为目标函数,采用Kriging方程建立近似替代模型预测响应应变误差,并结合...