游动芯棒拔制显式动力分析

借助ANSYS软件显式动力模块建立了游动芯棒拔制三维有限元模型,动态模拟了游动芯棒拔制的整个过程,根据得到的应力分布规律分析了生产中产生横裂问题的机理。并将拔制力分为四个阶段:起始、初步接触、完全接触、稳定。由于合理配模锥角是游动芯棒是否能稳定在变形区的最显著因素,就此对配模锥角进行了优化,所得结果可为游动芯棒配模锥角选择提供可靠的依据。     

The methods of analysis of the process of plug drawing of bimetallic tubing applied to implosively welded composites

Approximate upper bound, force-equilibrium and Shield-type analyses have been modified to account for the effects of friction and strain-hardening in plane strain, plug drawing of co-axially, integrally, welded bimetallic tubing without back-pull. A comparison between experimental and theoretical results indicates that even approximate theories give a reasonably satisfactory measure of agreement; with the upper bound approach being more accurate in the lower range of strains, and the lower bound theories approximating better in the higher range. The Shield-type analysis is preferred because of its ability to indicate the distribution and magnitude of shear stress—in itself an important parameter of the drawing operation.     

Some technological aspects of cold plug drawing of implosively welded duplex tubing

The demand for composite, structurally strong, components has been growing steadily in the atomic energy, chemical, electrical and electronic, and aircraft industries. In addition to multimetallic sandwich plates, duplex tubular components have gained in importance, particularly where heat exchangers, pressure vessels, insulating systems and remote control rods are of importance.Bimetallic tubing is normally produced by co-extrusion or axial co-drawing and although these techniques are often satisfactory, they are likely to be inadequate in more sophisticated heat-exchange etc. systems where integral composites are required, or where more unusual combinations of, possibly, refractory metals are needed. The integrity of such systems or, indeed, their availability, can be assured however, if explosive welding is adopted.Although implosive welding of long tubes is feasible, the levels of energy required to produce them and the quality of the weld obtained may not be acceptable in industrial situations. Consequently, relatively short, large diameter, tubing is welded and is then conventionally processed. In the absence of any lubricant, grease, grit or other impurities on the weld interfaces, heat flow and, of course, mechanical properties, are substantially improved.This paper is concerned with an experimental assessment of the quality and mechanical properties of cold drawn, originally implosively welded, bimetallic tubing, and with the methods of testing.     

The influence of ultrasonic vibration-assisted micro-deep drawing process

Micro-deep drawing process combined with ultrasonic vibration were performed on three stainless steel 304 foils of different thicknesses to determine the influence of ultrasonic vibrations on micro-cup formability and the limit drawing ratio (LDR). An ultrasonic system that applies 20 kHz of oscillation at various amplitudes was developed, and a concentrator was used to transfer the oscillation from the transducer to the die. The LDRs of these foils were obtained with and without ultrasonic variations. The experimental results in this study showed that using ultrasonic vibration following the deep drawing processes increased the LDR from 1.67 to 1.83, from 1.75 to 1.92, and from 1.83 to 2 for thicknesses of 50, 75, and 100 μm, respectively. The oscillation amplitudes had a significant effect on different thicknesses. An amplitude of 8.6 μm could not be appropriately applied to foils because of the excessive oscillated force. The punch force also decreased as the oscillation amplitude increased because of reduced friction between the die and the blank. Based on these experimental results, this study showed that ultrasonic vibrations can be used to produce micro-cups that exhibit high application flexibility in miniaturization technology.     

小盖拉深胀形镦压模具设计

小盖拉深胀形镦压模具是用来生产GHT6472盘式制动器轮廓组件上轴承的防尘盖零件．该零件虽然结构不复杂，但尺寸精度要求较高．给成形带来困难，为解决此问题，通过对零件的工艺分析、计算，零件拉深成形的特点分析，成形工艺的确定，胀形镦压的条件验算．进行了合理的模具结构设计。     

Numerical analysis of friction influence and die geometry on the quality of product in the forward extrusion process of tubular copper electrodes

The results of a numerical analysis of the extrusion of tubular electrolytic-copper electrodes are presented. The numerical analysis is based on the finite-element method (FEM) in DEFORM software. This method makes it possible to predict the formation of a microstructure, characteristics of the material, and factors in the process that improve the mechanical properties of the articles.     

A newly developed plug in the drawing process for achieving the high accuracy of aluminum rectangular tube

Aluminum rectangular tube is the key component in the field of microwave transmission whose service condition requests strict dimensional accuracy and internal surface quality. To meet these requirements, a newly developed plug featuring a tiny boss club structure in the sizing zone has been proposed in the plug drawing process. The optimal combination of the dimensions in the boss club has been obtained using the method of 3D finite element simulation and orthogonal experimental design. The plastic strain distribution, the contact status between the tube inner surface and the plug, the dimensional accuracy of the formed part, and the forming load have been compared between conditions where the traditional linear-type plug and this new type of plug have been used, respectively. It can be seen clearly that when the plug with a tiny boss club structure is adopted, the contact quality is better and the larger plastic strain exists on the inner surface of the tube, which is very crucial in improving the surface finish of the formed part. Meanwhile, the deviation of wall thickness and the axial length in the formed part is smaller based on the new type of plug. The experiment of the drawing process with two types of plugs has been carried out in which the surface finish of the inner tube surface and the wall thickness have been measured and compared. Experiment result shows that the dimensional accuracy and inner surface quality meet the requirements of the service condition when the plug with a tiny boss club structure is employed.     

凸缘矩形件的拉深工艺分析与模具设计

根据凸缘矩形件的结构特点及技术要求,用DYNAFORM软件进行拉深成形数值模拟分析,确定了落料拉深复合成形的工艺方案,缩短了复杂零件成形模具试错的过程,减少了对设计经验的依赖程度,提高了模具设计的准确性和可靠性,对同类零件的冲压模具设计具有一定的参考价值。介绍了模具结构及工作过程,对设计注意事项进行了分析、归纳和总结。     

电火花线切割中热效应现象及其对模具质量影响

热效应是电火花线切割加工模具时的固有现象,将热效应影响范围分为7个区,并分析对模具质量的影响,指出模具热效应区中的过热区和淬火区产生的残余应力和微裂纹是影响模具制造质量的重要原因,并制定相应的解决办法与对策.实例表明,用热效应现象分析和解决模具电火花线切割的质量问题是非常有效的.     

基于UG的汽车覆盖件拉深模具设计

基于UG平台开发了汽车覆盖件拉伸模具结构设计的模板化CAD系统.传统的汽车覆盖件拉伸模具设计方法设计周期较长,设计效率较低,为了提高设计效率,基于UG强大的功能,引进了标准化、参数化、模板化设计思想,在UG平台的基础上开发了汽车覆盖件拉伸模结构设计的模极化CAD系统.采用该系统对后地板左右连接板专用模具结构进行设计试验,试验结果表明该CAD系统大大简化了设计过程,提高了设计效率.     

The influence of contact geometry on friction and wear characteristics

This paper describes some results of evaluating the influence of contact geometry on tribological characteristics. Friction characteristics obtained for a distributed contact (pin‐on‐disc and block‐on‐ring), a linear concentrated contact (pin and vee‐block and block‐on‐ring) and a point concentrated contact (ball‐on‐disc and three cylinder‐cone) are presented. The wear scars were analysed using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The results show different values of friction and wear coefficients for the different types of contact geometry. The paper also assesses the effect of non‐test characteristics, e. g., vibration.     

基于CBR和KBE的拉深模系统

本文采用CBR与KBE相结合的技术,在研究拉深件的几何描述方法的基础上,通过构造相似度函数,来判断当前拉深件与拉深件事例库中拉深件的相似程度;采用最近邻法采检索事例库中最相似的拉深件,并重用其成形参数和工艺方案采判断新产品成形合理性.文中研究了拉深模设计系统中模具结构原型库基于知识的参数化实施方法,以及根据拉深件形状和尺寸特征生成拉深件特征骨架,从而形成最终的拉深模具结构的方法.所研究的拉深模具设计系统不仅能根据拉深件尺寸和特征,还能基于生产批量、产品材料等内容并结合实际经验,在知识库的辅助下.通过模具结构选择、参数驱动、零部件设计与修改,完成模具设计过程.     

The effect of normal stress on hydro-mechanical deep drawing process

Normal stress has some role in the deformation analysis of hydroforming processes. In this study, analytical modeling is pursued to evaluate the effect of normal stress on the hydro-mechanical deep drawing (HDD) process. Analyses are carried out for axisymmetric elements of the formed cup-shaped part for increments of the punch travel. The formulations are obtained using mechanical and geometrical relations and the finite difference method, thereby being solved by proper numerical algorithms. Furthermore, in the present work, part thickness is variable, the loading and straining are non-proportional, and bending/unbending effects over the part curvature are considered. The results show that there are some differences between thickness values, radial and circumferential strains and stresses, and punch force under plane stress and three-dimensional stress conditions. Thus, the normal stress should be considered in the design of HDD processes in order to improve accuracy.     

The influence of lubrication in rectangular deep drawing

Rectangular deep drawing is a widely used process in the electrical, automobile, and aeronautical industries, in military engineering, etc. Despite its popularity little information is available about the effect of lubrication on limiting drawing ratio, drawing force, and work done. In view of this, rectangular deep drawing experiments were conducted using mild steel, aluminium, and tin sheets in a 100 t double action hydraulic press. The maximum drawing force, the work done during drawing, and the limiting drawing ratio for a number of commercial lubricants were measured, and are reported in this paper. The effect of anodising has also been studied in the case of aluminium sheets. In the case of mild steel sheets the effect of shot blasting the blank has also been reported.     

拉深模试冲故障模糊综合诊断系统的研究

建立了拉深模故障模糊综合诊断模型,使用Delphi语言开发了一个拉深模故障模糊综合诊断系统.介绍了系统的总体结构和各模块功能,阐述了拉深模故障综合诊断系统知识库的推理过程.     

大型拉深模的设计

分析了大型拉深模的设计难点,并以膨胀器罩为例简述了模具的设计过程,使用效果良好。     

基于AutoCAD的塑料模标准件参数化图形库的开发

介绍了在AutoCAD软件平台下,以Access软件建立数据库管理系统,利用参数化和VBA语言开发塑料模标准件参数化图形库,并用实例介绍了开发过程.该系统的建立与使用能缩短模具设计的周期和提高工作效率.仿此能进行其它专业的参数化图库的开发.     

Geometry factors and inhomogeneity of flow in rotary piercing and cold drawing of seamless tubing

An assessment of the levels of inhomogeneous or redundant flow, as reflected by the redundancy factors, in the basic rotary-piercing and cold tube drawing processes, is made by means of derived geometry factors. The validity of the approach is tested against the experimental data. A generally satisfactory measure of agreement which exists between the proposed factors and the experimentally established inhomogeneity of the deformation, particularly in drawing, indicates the possibility of utilising this simple method in the computation of stress and strain levels in the tube making processes.