盒形件增量拉深成形模具设计及工艺试验

阐述了盒形件增量拉深成形原理,介绍了盒形件增量拉深成形毛坯尺寸的确定,简述了增量拉深成形盒形件模具设计过程。利用该拉深模在GLeeble1500D热模拟实验机上进行了工艺试验,成功地实现了一个凸模生产两类盒形件的试验目的。     

304不锈钢壳级进模变薄拉深工艺及数值模拟

根据经验公式和理论数据对某304不锈钢壳进行直径减小、壁厚变薄的变薄拉深级进模设计,并运用Deform-3D对连续变薄拉深成形过程进行数值模拟,揭示了成形过程等效应力和行程载荷曲线的分布规律。模拟与试验结果表明:成形过程中,坯料的最大应力集中在与凹模圆角和凹模工作带相接触的区域;随着凸模圆角减小,凸模圆角与直壁连接处应力增大,出现危险区域;为防止最后一道拉深过程中凸模容易磨损及产品被拉伤,应合理设计拉深系数、变薄量及凹模圆角;直径减小壁厚变薄拉深件的直壁壁厚均匀。     

筒形件粉末软凹模拉深数值模拟及实验

采用MSC.Marc软件对圆筒件粉体软凹模拉深成形进行数值模拟,分析成形过程中应力状态和变形情况,设计圆筒件粉体软凹模拉深成形实验模具,对圆筒件粉体软凹模拉深成形进行实验研究。有限元模拟与实验结果表明,与刚性凹模拉深成形相比,粉体软凹模成形工艺可以改善零件成形受力状态和壁厚分布,能有效抑制圆筒件凸模圆角破裂危险区域微裂纹的产生,提高板材的成形极限。     

筒形件粉末软凹模拉深数值模拟及实验

采用MSC.Marc软件对圆筒件粉体软凹模拉深成形进行数值模拟,分析成形过程中应力状态和变形情况,设计圆筒件粉体软凹模拉深成形实验模具,对圆筒件粉体软凹模拉深成形进行实验研究。有限元模拟与实验结果表明,与刚性凹模拉深成形相比,粉体软凹模成形工艺可以改善零件成形受力状态和壁厚分布,能有效抑制圆筒件凸模圆角破裂危险区域微裂纹的产生,提高板材的成形极限。     

带翻边拉深件的成形工艺设计及数值模拟

研究了带翻边拉深件的成形工艺,通过对零件结构的分析比较,确定了合理的成形工艺方案;采用Dynaform软件对拉深件的坯料尺寸进行估计,简化了计算过程,同时对拉深件的成形过程进行数值模拟分析,用初步的模拟结果验证了成形方案和工艺参数的合理性;设计拉深模具,通过生产试模,生产出了合格产品,对试模结果与模拟结果进行比较,得到了较好的一致性。     

基于FEM的圆筒件拉深工艺参数优化设计

采用Deform-3D软件对圆筒件拉深成形过程进行数值模拟,分析了不同凹模圆角半径下的拉深工艺参数对成形质量的影响,揭示了压边力与筒壁最小厚度、拉深件高度以及凸模压力之间的变化关系,得出了拉深工艺参数的优化方案,有效解决了工艺参数设计时理论和经验公式计算误差较大的问题.结果表明:基于有限元模拟的成形工艺参数优化是可靠的,可为高效的模具设计和生产提供科学依据.     

矩形盒深拉深成形有限元模拟

针对矩形盒成形过程中各种形式的起皱和拉裂问题，采用MSC．Marc有限元分析软件对矩形盒深拉延成形过程进行模拟。建立了包括板料、凸模、凹模及压边圈在内的整体分析模型，通过对成形过程中拉深件的等效应力进行比较，分析了不同的凸模圆角半径、凹模圆角半径及凸模角半径对矩形盒拉深成形的影响。此外，还对模拟结果做了进一步的分析，得出了凸凹模圆角半径之间的相应关系，以便合理的确定矩形盒深拉延成形时二者的取值范围。考察了模拟方法的可行性和可靠性。     

基于正交试验的级进模连续拉深带料的数值模拟

根据理论数据和经验公式对某不锈钢筒形件进行了连续拉深级进模设计,并对带料的连续拉深成形过程进行了数值模拟,预测了成形过程中出现的起皱和破裂缺陷.采用正交试验分析了压边力、摩擦系数和凹模圆角半径等参数对成形质量的影响,得到了拉深结束后制件的最大变薄率.通过对实验结果分析,得到了使制件减薄最小和消除筒壁起皱的成形参数.通过优化分析,消除了成形过程中出现的缺陷,得到了合理的成形参数.这能为实际生产提供指导.     

异形件成形工艺与模具设计

分析了异形件成形工艺,利用UG和Dynaform软件确定了零件的毛坯形状及尺寸,介绍了异形件落料拉深复合模结构设计和工作过程,对异形件拉深过程进行了数值模拟,根据模拟结果分析了成形性能。     

基于DEFORM-2D的304奥氏体不锈钢拉深过程应力应变的数值模拟

不锈钢板材在拉深成形过程中应变硬化严重,影响因素复杂,易出现起皱、破裂、黏模等现象.运用DEFORM-2D的有限元软件,对不同拉深工艺条件下304奥氏体不锈钢圆筒件的拉深成形过程进行了数值模拟,分析了不同工艺条件下的应力应变情况.结果表明:工件凸缘处的摩擦因数越大,拉深成形极限高度hmax越小;提高拉深速度或降低摩擦因数,拉深成形极限高度hmax增大.通过几种不同条件下的模拟分析发现,在模拟实验条件范围内,304奥氏体不锈钢圆形件拉深成形的最佳成形条件为:凸模圆角rp=3mm、凹模圆角rd=3mm、凸缘处的摩擦因数μ=0.08、拉深速度v拉=30mm/s.这与实际生产中的情况相吻合,产生破裂的部位也与实际一致.     

Development of incremental deep drawing process

This paper deals with development of an incremental deep drawing process. On a newly developed incremental deep drawing set-up, the aluminium sheets are formed; the forming is carried out by deep-drawing the blank as in the conventional method but incrementally. Fractures at the punch or die corner in the blank may or may not occur depending on the conditions; the process parameters involved are punch size, punch corner radius, increment in punch displacement, blank holding force or pressure, etc. It is thus shown that different shapes are formed by one set of common tools. It is thereby confirmed that incremental deep drawing is possible without using a particular tool set for a particular shape.     

Cold Deep Drawing of Commercial Magnesium Alloy Sheets

A cold deep drawing process for commercial AZ31 magnesium alloy sheets was developed. The commercial sheets were successfully formed into circular cups at room temperature by optimising the annealing temperature of the sheets, i.e. a limiting drawing ratio of 1.75 was attained for an annealing temperature of 500 °C. The increases in elongation, n-value and r-value, and the decrease in flow stress effective in the improvement of drawability were obtained for the annealing. The apparatus for cold deep drawing without heating becomes much simpler than that for the conventional warm deep drawing. The effects of the lubricant, the clearance between the die and the punch and the corner radius of the punch on the drawability were examined. The limiting drawing ratio was increased by applying force onto the edge of a blank through the die corner. In addition, cold deep drawing of magnesium alloy square cups was performed. It was found that comparatively shallow magnesium alloy cups are satisfactorily formed at room temperature without heating.     

汽车轮毂端盖拉伸成形模计算机辅助工程

建立了汽车轮毂端盖拉伸成形三维弹塑性有限元模型,并利用MARC软件对其拉伸变形过程进行了数值模拟。分析了金属材料在拉伸成形时的流动及拉伸成形后的残留应力和应变分布情况,研究了凸模圆角半径对板料成形性能的影响及防止产生起皱与破裂的措施。研究结果表明,当凸模圆角半径值小于2~3倍料厚时,材料易产生拉裂现象。模拟结果与实际生产吻合较好,说明所建立的有限元模型是合理的。     

Influence of variables in deep drawing of AA 6061 sheet

Deep drawing is one of the most important processes for forming sheet metal parts.It is widely used for mass production of cup shapes in automobile,aerospace and packaging industries.Cup drawing,besides its importance as forming process,also serves as a basic test for the sheet metal formability.The effect of equipment and tooling parameters results in complex deformation mechanism.Existence of thickness variation in the formed part may cause stress concentration and may lead to acceleration of damage.Using TAGUCHI's signal-to-noise ratio,it is determined that the die shoulder radius has major influence followed by blank holder force and punch nose radius on the thickness distribution of the deep drawn cup of AA 6061 sheet.The optimum levels of the above three factors,for the most even wall thickness distribution,are found to be punch nose radius of 3 mm,die shoulder radius of 8 mm and blank holder force of 4 kN.     

Finite element modeling and experimental results of brass elliptic cups using a new deep drawing process through conical dies

This paper introduces a new technique for deep drawing of elliptic cups through a conical die without blank holder or draw beads. In this technique an elliptic-cup is produced by pushing a circular blank using a flat-headed elliptic punch through a conical die with an elliptic aperture in a single stroke. A 3D parametric finite element (FE) model was built using the commercial FE-package ANSYS/APDL. Effects of die and punch geometry including, half-cone angle, die fillet radius, die aperture length and punch fillet radius on limiting drawing ratio (LDR), drawing load and thickness strain of the cup have been investigated numerically for optimal process design. A die with half cone angle of 18° has shown the best drawability for the new technique. An experimental set-up has been designed, manufactured, and used for experimental production of elliptical shaped sheet-metal cups. A total of seven punches having aspect ratios ranging from 2 to 2.25 and a die with an aspect ratio of 2 have been manufactured and used. Tensile tests were carried out to obtain the stress–strain behavior for the formed sheet metal. Experiments were conducted on blanks of brass (CuZn33) with initial thicknesses of 1.5, 1.9, 2.4 and 3 mm at different clearance ratios (c/t). Effects of blank thickness and clearance ratio on limiting drawing ratio, drawing load and thickness strain were numerically and experimentally investigated. Finite element model results showed good agreement with experimental results. An elliptic cup with a limiting drawing ratio (LDR) of 2.28 has been successfully achieved using the proposed technique and set-up.     

Two-stage cold stamping of magnesium alloy cups having small corner radius

A two-stage cold stamping process for forming magnesium alloy cups having a small corner radius from commercial magnesium alloy sheets was developed. In the 1st stage, a cup having large corner radius was formed by deep drawing using a punch having large corner radius, and the corner radius of the cup was decreased by compressing the side wall in the 2nd stage. In the deep drawing of the 1st stage, fracture was prevented by decreasing the concentration of deformation with the punch having large corner radius. The magnesium alloy sheets were annealed at 500 °C to increase the cold formability. Circular and square cups having small corner radii were formed by the two-stage cold stamping. For the circular cup, the height of the cup was increased by ironing the side wall in the 1st stage. The radii of the bottom and side corners of the square cup were reduced by a rubber punch for applying pressure at these corners in the 2nd stage. It was found that comparatively shallow magnesium alloy square cups used as cases of laptop computers and mobile phones can be satisfactorily formed at room temperature without heating by the two-stage stamping.     

Influences of material parameters on deep drawing of thin-walled hemispheric surface part

During deep drawing process, the material parameters of blank have a significant effect on the quality of the drawn part and the determination of process parameters. Here, a 3D finite element model is developed for the deep drawing process of a thin-walled hemispheric surface part. Then the influences of material parameters including hardening exponent n, yield stress σs and elastic modulus E on the process are investigated by simulation. The results show that the effects of n and σs on punch force, thickness variation and equivalent strain are more notable. The maximum equivalent plastic strain occurs outside the die corner. However, when the value of n is 0.03 or σs is smaller than 120 MPa, higher equivalent plastic strain occurs at ball top.     

外壳零件拉深模设计

分析了原有外壳零件多工序成形的缺点,提出了采用复合模加工的工艺。通过计算拉深凹模圆角半径、拉深凸模圆角半径、拉深间隙和拉深系数,并根据实际经验的取值,设计了1套复合模,实现了落料、拉深、整形一次成形,使外壳零件达到设计使用要求。该模具生产的外壳,外观美观,质量优良。     

Tool temperature control to increase the deep drawability of aluminum 1050 sheet

A feasibility study on the tool temperature control to increase the deep drawability of Al-1050 sheet is performed. The conventional deep drawing process is limited to a certain limit drawing ratio (LDR) beyond which failure will ensue. The purpose of this study is to examine the possibilities of relaxing the above limitation through the tool temperature control, aiming towards a process with an increased LDR. The idea which may lead to this goal is strengthening the punch-nose radius part by cold punch which has frequently been potential failure area in cup drawing process, while heating the remainder of the blank to reduce the stress on the cup sidewalls. Over the ranges of conditions investigated, the deep drawability of Al-1050 is found to be strongly sensitive to the temperature of the die and punch. The experimental implementation shows that the tool temperature control is very effective way to promote deep drawability of Al-1050.