楔横轧技术的应用及发展

介绍了楔横轧工艺的类型、应用、工艺参数及模具结构．当前楔横轧技术在理论和工艺方面的主要研究成果，以及目前楔横轧技术的应用情况和今后的发展方向，以期推动楔横轧技术在我国的发展。     

浅谈数控铣床在模具加工中编程

在当今模具加工编程过程中,其编程加工方法可以分为两大类:等高线法和包络线法。我们知道,加工任何一个工件首先要建立数学模型,编程无非是用计算机语言对算法的再实现,而等高线法和包     

楔横轧技术的应用及其效益

楔横轧是20世纪60年代发展起来的一种先进的锻压工艺。目前已在汽车、拖拉机、机床等行业普遍应用,并取得了显著的经济效益。 楔横轧是两个带楔形模具的轴心线平行的轧辊,以相同的方向旋转,带动棒料运动,同时棒料随轧辊在两导板中间进行自转,在轧辊楔形模具的作用下,旋转一周经楔入、展宽、成形、精整及切断,轧制成各种回转体零件。其成形原理和过程如     

PowerMILL在模具数控编程中的应用

介绍了PowerMILL的特点、优势、操作方法与步骤,并以相机外壳模具的数控编程为例,详细叙述了编程步骤、加工策略、工艺参数以及仿真效果。     

模具数控加工编程的应用技巧

由于模具的形状各异,因此,在数控加工编程中,仅仅利用常用的编程指令是不够的,它将使零件的加工程序复杂,各点的计算困难,加工误差增大等.介绍了模具的数控加工编程技巧,目的在于简化程序的编制,提高零件的加工精度.     

汽车锻件加工新技术：汽车车桥主动伞齿轮坯的楔横轧模具和立镦模具（三）

2.楔横轧模具 为使轧件在轧制过程中的受力平衡,亦即轴向合力为零,切向力对等,轧件既不发生轴向串动,也不产生切向扭曲,以实现稳定轧制,需要将两个EQ140汽车车桥主动伞齿轮坯同轴逆向连接起来组成对称轴,进行成对轧制。因而它的轧制孔型的成形终了段剖面图如图9所示。     

数控编程在注塑模具制造中的应用

以实例说明了数控编程在注塑模具制造中的应用。     

楔横轧模具轧件信息的知识表达

楔横轧模具设计属弱理论领域,主要依赖设计人员的知识和经验,轧件信息直接决定楔横轧模具的设计.本文根据楔横轧轧件的特点,将轧件分解为基本单元体素,建立其知识对象模型,实现结构类和属性类的知识表达.     

Theoretical method for estimation of mean pressure on contact area between rolling tools and workpiece in cross wedge rolling processes

The paper gives a new method no determine the mean unit contact pressures on a material—tool contact surface in cross wedge rolling processes (CWR). The dependencies worked out on the basis of the energy and the upper bound methods permits rolling forces to be determined which are comparable to experimentally measured ones. The analysis provides equations which relate the mean contact pressure q_m to the basic process parameters, namely the forming angle α, the spreading angle β, the relative reduction of a portion δ and the shear friction factors m and m_k.     

Influence of cooling condition of tools on central deformation of workpiece and tool wear in cross wedge rolling

In this paper, a thermal–mechanical coupled simulation model for two-roll cross wedge rolling (CWR) was developed to investigate the influence of cooling condition of tools on central deformation of workpiece and tool wear by using three-dimensional rigid-plastic finite element method. Based on the simulation results, the information about central deformation of workpiece and tool wear with and without tool cooling was compared and analyzed. The study results indicate that forging quality and tool life can be improved by means of cooling the tools with cooling water. Subsequently, an industrial example of CWR in blank forming for engine connecting rod was presented to verify the feasibility of study results. In this industrial application, higher forging quality and longer tool life were obtained, which benefits the decrease of production cost. This study provides insights into the mechanisms of central deformation of workpiece and tool wear under different cooling conditions of tools in CWR process as well.     

The establishment of a failure criterion in cross wedge rolling

Internal defects in the cross wedge rolling (CWR) process can lead to the catastrophic failure of products. Using specialised experiments and the explicit dynamic finite element model (FEM), this work investigates the mechanisms of void generation and growth in the cross wedge rolling process. Based on a combined numerical and experimental approach, the morphology of void generation is determined as a function of the workpiece material and three primary parameters in the cross wedge rolling process: the forming angle, , the stretching angle, and the area reduction, _A . Through the definition of a non-dimensional deformation coefficient, , a method for predicting the likelihood of void formation is subsequently ascertained and discussed with respect to CWR tooling design and operating conditions.     

AutoCAD的二次开发软件VBA在数控铣一体化教学中的应用

探讨了AutoCAD2004的二次开发软件VBA在数控铣一体化教学中的实际应用,VBA可以用来实现参数化的刀路仿真。为了让学生更好地完成数控铣一体化学习,使教学过程更加清晰明了,充分利用AutoCAD2004的二次开发软件,在实际教学中取得了不错的效果。     

Analysis of stress in cross wedge rolling with application to failure

In the present investigation, a previously developed three-dimensional finite-element model for the cross-wedge rolling (CWR) process has been used to characterize the workpiece material stress and deformation behavior. Particular attention has been paid to the center and mid-radius points of the billet where internal defects (i.e. internal cracks and porous voids) often occur. Several failure criteria in the solid mechanics theory are summarized. The effect of three important CWR parameters, namely the forming angle, the area reduction, and the friction coefficient, on the field variables has been investigated, including the first principal stresses, maximum shear stresses, etc. A total of 14 rolling conditions are analyzed for the billet material aluminum alloy 1100. After initially verifying the numerical results, several tendencies for the CWR process, as related to failure, are ascertained and discussed.     

Study on the progressive forming mechanism of multi-step shafts based on convex-end billet in the cross wedge rolling technology

The deforming process is complicated and both the end concave and the central defect can be easily formed in multi-step shafts shaped by the cross-wedge rolling technology. To realize the accurate forming of multi-step shafts without stub bar, this article breaks the bondage of traditional flat-end billet, and introduces into convex-end billet. Based on established mechanical models and the damage computation principles, the distribution and change features of stress fields, strain fields and microstructures in different segments of the multi-step shaft during the progressive forming process are analyzed, and the location of the central defect is predicted. It is found that the concave depth of shaft ends decreases as the length of the convex-end of billet increases, the microcosmic grains are affected by the section shrinkage of the shaft segments and the larger the section shrinkage is, the smaller the size of the microcosmic grain will be. It records the longest duration of maximum stress, the largest fluctuation of lateral stress and the most frequent cycle of transverse strain in the multi-step shaft end and therefore the central defect is most likely to occur. The research findings settle a dependable theoretical basis for enhancing the molding quality and realizing the accurate forming for multi-step shafts in cross wedge rolling.

     

Influence analysis of area reduction for necking in twice-stage cross wedge rolling

A symmetric twice-stage cross wedge rolling (CWR) model was developed to analyze the generation mechanisms of necking by using rigid-plastic finite element method (FEM), and particular attention has been paid on the effect of area reduction on necking. After a brief summarize of necking criteria in single-stage CWR, the distribution coefficient of area reduction was presented to analyze the laws of necking in twice-stage CWR. The influences of area reduction on the field variables, including the effective strain, displacement, and damage, have been investigated to explain the laws of necking. With the necking behavior deteriorates, the displacement and damage increase. The traditional idea about distribution of area reduction is that the main deformation, which occurs in first stage, can effectively prevent necking in twice-stage CWR, but in this study, it has been found that the optimal state was achieved when the distribution coefficient of area reduction is close to 1. The production experiment on connecting rod preforming process was given to validate the simulation results. The results show that the law is desirable and gives a good guide for CWR die design.     

楔横轧轴向力对轧件质量的影响

分析了楔横轧零件时轴向力不平衡所导致的问题及解决办法.     

Analysis of a cross wedge rolling process for producing drive shafts

The paper discusses the problems of forming parts such as stepped shafts by cross wedge rolling (CWR). In industrial practice, this rolling process is performed at stages, i.e., in several passes, when large cross-sectional reductions are involved. The same can also be done using a different design of this forming process, namely, multi-wedge cross rolling (MWCR), in which the workpiece is simultaneously formed by several pairs of tools (wedges). This paper compares the above two methods with respect to forming a drive shaft. Wedge tools used in both forming processes are described, and the numerical results of the simulations performed to verify the adopted solutions are reported. The results demonstrate that the MWCR method offers more advantages than the classical CWR technique. Consequently, MWCR is then verified in experimental tests. The experimental results confirm that parts such as stepped shafts can be formed by the MWCR method.