基于响应曲面法的预成形模具优化设计

采用响应曲面法对预成形模具形状进行了优化设计,以终锻件能够完全充满型腔且飞边最小为优化目标,建立了数学建模。以工字型锻件为例,设计出了直线、圆弧和曲线3种预锻模形状,提取了直线的角度、圆弧的半径、四次曲线的拐点位置为设计变量。以Deform 2D为有限元模拟软件,对每种预锻模形状进行锻造过程模拟,根据模拟出的实验数据求得目标函数值。用曲线拟合软件1st Opt对形状设计变量和目标函数值之间的相互关系进行曲线拟合,得到相应的曲线方程,并对曲线方程求最优解,从而获得最佳角度为41°,最佳半径为109.1 mm,最佳拐点位置为0.3。通过对3种最优预锻模形状的比较,得出四次曲线型预锻模为最佳预锻模形状。     

曲轴锻模CAD系统的开发

本研究所开发的曲轴锻模ＣＡＤ系统是一个建立在ＡｕｔｏＣＡＤ软件包上的辅助设计平台，它提供了一系列适用于曲轴锻模设计的实用功能，设计师可运用这些功能进行曲轴锻件、热锻件、预锻件及锤锻模的设计，同时还可利用ＡｕｔｏＣＡＤ的各种工具进行图形处理，本文也讨论了实用化软件的开发思想。     

锻模CAD/CAM系统

随着对锻件精度的要求和锻模的设计与制造水平要求越来越高,在锻造业中应用三维ＣＡＤ／ＣＡＥ／ＣＡＭ软件也越来越迫切。本文结合本单位实际应用情况,系统阐述了从产品设计到锻模ＣＡＤ／ＣＡＥ／ＣＡＭ系统的应用。     

基于智能算法的轴对称锻件预成形优化设计

为提高轴对称锻件预成形优化设计的效率,提出了一种基于遗传算法和数值模拟相结合的轴对称锻件自动优化方法。在这种自动优化方法中,CATIA和DEFORM-2D协同工作,从而实现锻造工艺的参数化数值仿真;MATLAB优化工具箱对参数化数值仿真进行智能化控制,实现实时协调通信;此外,在该优化算法中,将锻件中零件本体内等效应变在给定范围[0. 5,1. 0]外单元体积的百分比作为优化目标,将预锻模的尺寸数据作为优化设计变量。最后,使用某轴对称锻件作为样件,并设计了两种方案进行优化测试。优化结果表明,该优化方法能够将锻件内等效应变在[0. 5,1. 0]范围内的单元体积百分比从85%提高到95%,并且没有折叠等缺陷。     

面向微观组织优化的锻造工艺预成形优化设计及实验研究

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,构建了锻造成形过程微观组织优化目标函数,并确定锻造成形预成形形状作为优化过程的设计变量。采用遗传算法和有限元模拟相结合的方法,开发了锻造过程微观组织优化程序,对典型的H型锻件进行了面向微观组织优化的预成形设计,取得了较好的效果。并根据优化设计的结果进行了实验研究,优化结果的晶粒尺寸及其分布趋势与实验结果比较吻合。     

工字型截面锻件预成形工艺CAD

针对工字形截面锻件的预成形设计问题，建立了一系列数学模型和锻模ＣＡＤ方法，开发了相应锻模、飞边槽ＣＡＤ软件和数据库，最后举例证实该方法的可靠性。     

面向微观组织优化的锻造工艺预成形优化设计

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,构建了锻造成形过程微观组织优化目标函数,并确定锻造成形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,取得了较好的效果.     

BRD连杆成形工艺和锻模设计

分析了BRD连杆的锻造工艺性,绿化了锻造工艺过程,优化了锻模结构(尤其是预锻模膛含预锻飞边槽和冲孔连皮的形状、结构与尺寸),提高了锻件质量、锻件合格品率、锻造效率和锻模使用寿命。     

基于Deform的铝合金盘体件锻造工艺参数对成形性能影响的分析

在复杂结构铝合金盘体件锻造过程中,预锻模结构对锻造质量的影响较大。本文分析了采用初始预锻模结构的锻件填充情况,并基于填充缺陷改进了预锻模结构,验证了改进后的预锻模结构对锻件填充、金属流速和锻件应力分布的影响,并对比分析了不同摩擦系数对锻件质量的影响。     

固定挡块顺序成形模锻法

分析了固定挡块的模锻工艺性,介绍了固定挡块顺序成形模锻法,优化了锻模结构(尤其是预锻模膛的形状、结构与尺寸)设计,提高了锻件质量、锻件合格品率、锻造效率和锻模使用寿命。     

Sensitivity analysis based preform die shape design for net-shape forging

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.     

Computer-aided preform design in forging of an airfoil section blade

This study attempts to establish systematic procedures for the preform design in forging of an airfoil section blade as a two-dimensional plane-strain problem. Forward loading and backward tracing simulations by the finite element method are used. A circular shape is selected as an original stock, and a side-pressed preform of the circular shape is adopted in view of preliminary simulations using rectangular preforms. The optimal slope angle of the die parting line and the position of the preform within the die, which satisfy the final design condition of flashless forging, are determined from the results of the simulations.     

Preform optimization for hot forging processes using an adaptive amount of flash based on the cross section shape complexity

In multistage hot forging processes, the preform shape is the parameter mainly influencing the final forging result. Nevertheless, the design of multistage hot forging processes is still a trial and error process and therefore time consuming. The quality of developed forging sequences strongly depends on the engineer’s experience. To overcome these obstacles this paper presents an algorithm for solving the multi-objective optimization problem in designing preforms. Cross wedge rolled preforms were chosen as subject of investigation. An evolutionary algorithm is introduced to optimize the preform shape taking into account the mass distribution of the final part, the preform volume and the shape complexity. A crucial factor in preform optimization for hot forging processes is the amount of flash. Therefore an equation for improving the amount of flash is derived. The developed algorithm is tested using two connecting rods with different shape complexities as demonstration parts.     

Sensitivity analysis based preform die shape design using the finite element method

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.     

滑动叉无飞边锻造工艺研究

滑动叉传统上采用开式模锻工艺生产,飞边大,材料浪费严重而且尺寸精度差。为了降低锻件成本,针对滑动叉的形状特征,提出一种无飞边模锻的新工艺,使预制毛坯在封闭的模腔内成形,实现净成形或近净成形。应用Deform 3D模拟研究了滑动叉无飞边锻造工艺过程,模拟验证结果表明,新工艺显著地提高了材料利用率和成形质量,降低了锻造载荷。     

齿轮坯闭式模锻模具参数化设计系统的研制

针对齿轮坯闭式模锻模具设计，详细研究了其参数化设计过程及其二次开发的方法和技术，成功开发了齿轮坯闭式模锻模具参数化设计系统，实现了齿轮坯闭式模锻模具参数化绘图。     

滑动叉无飞边锻造工艺有限元模拟研究

滑动叉传统上采用开式模锻工艺生产,飞边大,材料浪费严重且尺寸精度差。为了降低锻件成本,针对滑动叉的形状特征,提出一种少无飞边模锻的新工艺,使预制毛坯在封闭的模膛内成形,实现锻件近净成形。根据体积不变原则对计算毛坯进行处理得到预制毛坯。应用DEFORM 3D软件模拟研究了滑动叉无飞边和小飞边锻造工艺过程,模拟验证结果表明,新工艺显著地提高了材料利用率和成形质量,降低了锻造载荷。     

Optimum design of forging dies using fuzzy logic in conjunction with the backward deformation method

A novel shape optimization method is presented for the design of preform die shapes in multistage forging processes using a combination of the backward deformation method and a fuzzy decision making algorithm. In the backward deformation method, the final component shape is taken as the starting point, and the die is moved in the reverse direction with boundary nodes being released as the die is raised. The optimum die shape is thereby determined by taking the optimum reverse path. A fuzzy decision making approach is developed to specify new boundary conditions for each backward time increment based on geometrical features and the plastic deformation of the workpiece. In order to demonstrate this approach, a design analysis for an axisymmetric disk forging is presented in this paper.     

Fast 3D inverse simulation of hot forging processes via Medial Axis Transformation: an approach for preform estimation in hot die forging

In hot die forging processes, the selection of an ideal preform is of great importance with respect to cavity filling and mechanical load. The common procedure in order to define an adequate preform is the usage of Finite-Element-Analysis (FEA), usually as an iterative process in which various preforms are tested with regard to their suitability. An approach that aims at reducing the number of trials by proposing a first estimation of a suitable preform is presented in this paper. It is conjectured that the material flow paths and resistance can be described by the cavity shape using the Medial Axis Transformation. Based on this, a local inverse material flow for time discrete steps is calculated. The result is a first estimation of an adequate preform shape within a few minutes as an input for further FEA. FE-based parametric design optimization procedure is then presented and compared to the inverse approach, which is identified as a useful complement for the forward simulation technique.     

羊角锤闭式精密模锻工艺及模具设计

叙述了羊角锤新旧模锻工艺过程,介绍了活动模具的动作原理及模具结构,阐述了用闭式精密模锻工艺代替普通模锻的优点,提出了模具设计的基本要求,指出了目前使用活动模具闭式精密模锻中所存在的问题