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对中空气门楔横轧-模锻成形工艺终锻成形过程中的凸模形状尺寸进行研究。根据预成形毛坯终锻过程的成形特点,设计3种不同初始尺寸的终锻成形凸模,采用实验与模拟相结合的方法研究其对预成形毛坯终锻成形过程的影响。模拟结果表明,终锻成形过程中凸模芯轴太短,将出现凸模芯轴前端聚料的现象,导致无法成形出终锻件的盘部型腔尺寸;而实验结果表明,凸模芯轴太长会在实际生产中导致成形后终锻件难以脱模。通过综合模拟与实验结果的分析,获得了凸模芯轴的设计原则,确定了合适的凸模芯轴长度,并且依据该凸模设计原则,进行终锻成形,获得了形状尺寸合理的终锻件。 相似文献
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基于Deform对某航天器X部件毛坯成形过程进行模拟分析,结果表明不同预锻毛坯形状对最终产品成形性有着很大影响,另外通过模拟可以预判锻件易产生裂纹等风险部位。最终依据模拟工艺确定了预锻毛坯形状,并成功实现了模锻生产,产品尺寸以及各项性能均满足技术要求。 相似文献
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基于微观组织优化的锻造工艺预成形及毛坯形状优化设计 总被引:3,自引:0,他引:3
以锻件晶粒尺寸细小均匀为目标,以预成形形状设计为对象,提出了锻造成形过程微观组织优化设计方法,构建了晶粒尺寸、锻件形状子目标函数以及无量纲化的总目标函数,确定了预成形形状作为优化过程的设计变量;给出了优化设计的具体步骤,采用微观遗传算法和有限元模拟方法开发了基于预成形设计的锻造过程微观组织优化程序;并对典型的圆柱体镦粗进行了面向微观组织优化的预成形设计,给出了能够获得具有良好微观组织的镦粗成形预成形模具型腔形状。通过分析不同高径比的初始毛坯形状对微观组织优化目标函数值的影响,给出了较为合理的初始毛坯形状高径比取值范围。 相似文献
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G. Q. Zhao R. Hufi A. Hutter R. V. Grandhi 《Journal of Materials Engineering and Performance》1997,6(3):303-310
This paper uses a finite element-based sensitivity analysis method to design the preform die shape for metal forming processes.
The sensitivity analysis was developed using the rigid visco-plastic finite element method. The preform die shapes are represented
by cubic B-spline curves. The control points or coefficients of the B-spline are used as the design variables. The optimization
problem is to minimize the difference between the realized and the desired final forging shapes. The sensitivity analysis
includes the sensitivities of the objective function, nodal coordinates, and nodal velocities with respect to the design variables.
The remeshing procedure and the interpolation/transfer of the history/dependent parameters are considered. An adjustment of
the volume loss resulting from the finite element analysis is used to make the workpiece volume consistent in each optimization
iteration and improve the optimization convergence. In addition, a technique for dealing with fold-over defects during the
forming simulation is employed in order to continue the optimization procedures of the preform die shape design. The method
developed in this paper is used to design the preform die shape for both plane strain and axisymmetric deformations with shaped
cavities. The analysis shows that satisfactory final forging shapes are obtained using the optimized preform die shapes. 相似文献
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Large-sized frame forging of Ti-alloy is an important forced component of aircraft. The frame forging has complicated shape
which leads to great difficulties in deformation. Some defects may be produced during the forming process such as un-filling
or overlapping. Preform design is an effective method for producing qualified forging. In this article, a new method based
on 3-D electrostatic field simulation is proposed to design preform of a large-sized frame forging of Ti-alloy and a geometric
transformation method is introduced to obtain the preform dimension. In order to select more suitable preform of large-sized
frame forging, FEM software Deform-3D is employed to simulate the isothermal forming process of designed preform. Deformation
uniformity index ψ is introduced as a criterion to judge the forging quality and the most appropriate preform is obtained
by virtual orthogonal test design. 相似文献
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本文用常温云纹法与数值模拟法研究了筒体锻件整体镦粗与局部镦粗工艺的变形规律,得到了整体镦粗工艺的坯料尺寸图。对于在端部内壁处取样的核电筒体锻件,应采用局部镦粗工艺,以锻透取样部位。为避免端部折叠,局部镦粗时单砧压下量应小于10%。 相似文献
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基于有限元灵敏度分析的锻造成形微观组织优化设计 总被引:2,自引:0,他引:2
采用有限元、灵敏度分析与工程优化算法相结合的方法,以能充满型腔且少无飞边的终锻件的晶粒度分布均匀化为目标,以预成形形状为优化对象,对锻造成形过程的微观组织进行了优化设计。采用三次B样条函数描述预成形模具形状,并以B样条函数的控制点坐标为设计变量,给出了锻造过程微观组织演变的模型,建立了衡量锻件充型性能及微观组织分布均匀化的目标函数,推导了目标函数对设计变量的灵敏度,给出了优化设计步骤。并以一典型H型锻件为例,对锻件的微观组织进行了优化,取得了较好的结果。 相似文献
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材料塑性成形过程最优化设计—Ⅰ有限元灵敏度分析方法 总被引:16,自引:2,他引:14
本文采用有限元方法建立了一种非稳态材料塑性成形过程的灵敏度分析理论和模具形状优化设计方法。采用三次B样条函数描述预成形模具形状,B样条函数的控制点坐标(系数)作为优化设计变量,通过对控制点坐标的优化设计,使实际终成形件形状与理想终成形件形状之间的差别最小,从而实现预成形模具形状的优化设计,详细建立了目标函数、有限元节点坐标、节点速度对优化设计变量的解析灵敏度方程及其彼此之间的数学关系,并给出了节点速度灵敏度的边界条件 相似文献
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Computer aided preform design in forging using the inverse die contact tracking method 总被引:2,自引:0,他引:2
G. Zhao E. Wright R.V. Grandhi 《International Journal of Machine Tools and Manufacture》1996,36(7):755-769
The inverse die contact tracking method presented in this paper utilizes both the forward and inverse finite element simulations to design the preform shapes in forging processes. The procedure starts with the forward simulation of a candidate preform into the final forging shape. A record of the boundary condition changes is produced by identifying when a particular segment of the die makes contact with the workpiece surfaces in forward simulation. This recorded time sequence is then optimized according to the material flow characteristics and the state of die fill to satisfy the requirement of material utilization and forging quality. The modified boundary conditions are finally used as the boundary condition control criterion for the inverse deformation simulation. Additionally, a procedure to determine process staging points using trial forward simulation is given. As an example, the preform design of a plane strain forging process is performed. The fuller, buster and blocker dies are designed by using the inverse deformation simulation. 相似文献
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Guoqun Zhao Ed Wright Ramana V. Grandhi 《International Journal of Machine Tools and Manufacture》1997,37(9):1251-1271
A sensitivity analysis method for preform die shape design in net-shape forging processes is developed in this paper using the rigid viscoplastic finite element method. The preform die shapes are represented by cubic B-spline curves. The control points or coefficients of B-spline are used as the design variables. The optimization problem is to minimize the zone where the realized and desired final forging shapes do not coincide. The sensitivities of the objective function, nodal coordinates and nodal velocities with respect to the design variables are developed in detail. A procedure for computing the sensitivities of history-dependent functions is presented. The remeshing procedure and the interpolation/transfer of the history-dependent parameters, such as effective strain, are stated. The procedures of sensitivity analysis based preform die design are also described. In addition, a method for the adjustment of the volume loss resulting from the finite element analysis is given in order to make the workpiece volume consistent in each optimization iteration. The method developed in this paper is used to design the preform die shape of H-shaped forging processes, including plane strain and axisymmetric deformations. The results show that a flashless forging with a complete die fill is realized using the optimized preform die shape. 相似文献
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Magnesium alloys have relatively low workability at room temperatures due to hexagonal crystal structure. In general, the forging process of magnesium alloys is considered to be very difficult because of the poor flowability and the sensitivity to the temperature and strain rate. Taken spur bevel gear as an example, the hot forging process of the complicated shape parts of magnesium alloy AZ31B was investigated by means of finite element (FE) simulations combined with experiments. After the two-stage hot forming process (preforming operation without gear shape and finish forging operation) was determined, the influence of various shapes of preform dies on the hot forging process was discussed by the commercial finite element analysis software Marc, and the optimum preform die shape was obtained. According to the numerical simulation results, the hot forging experiments of magnesium alloy AZ31B spur bevel gear were successfully conducted. By comparison between experimental load–stroke curves and the calculated ones, it shows that the calculated results are consistent with the experimental ones. 相似文献
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设计合适的锻压坯料是保证锻压后锻件具有良好综合性能的基础,通过改进锻压坯料的尺寸来改善锻件各部位的变形程度以获得具有良好组织及性能的锻件。运用有限元模拟软件Deform-3D模拟联接轴等温模锻过程,对不同尺寸的坯料模拟等温锻造过程,随着坯料在Z向厚度尺寸的增加,模锻后锻件的等效应变随之逐渐增加。选择成形效果较佳且模锻后锻件变形程度逐渐增加的锻压坯料进行实验。对热处理后的等温模锻件进行室温拉伸、硬度、电导率、疲劳以及金相实验检测。结果显示:对于横截面沿长轴突变的联接轴锻件,锻件各部位间性能差异较大;等温模锻后,变形程度大的锻件能够获得更好的微观组织和力学性能。 相似文献