盒形件增量拉深成形数值模拟及工艺试验

为了探索板料增量拉深成形的特点和规律,设计了增量拉深成形轨迹,用Deform-3D模拟软件,对盒形件增量拉深过程进行了数值模拟,分析了凹模圆角半径和凸模进给速度对成形件质量的影响,获得了成形过程中的等效应力和等效应变;并设计了具有双向调节机构的增量拉深模,在Gleeble1500D热模拟试验机上进行了工艺试验验证.结果...     

铝合金筒形件的电磁脉冲辅助渐进拉深成形

铝合金的室温成形性较差,用传统压力机拉深成形时,在凹模内径不变一道次拉深的条件下,极限拉深高度较低。采用电磁辅助拉深成形方法,可以将工件的拉深高度提高到传统方法的1.44倍。文章设计了一种具有法兰助推拉深能力的环形线圈结构,形成了拉深与助推联合作用的电磁脉冲辅助渐进拉深成形工艺。试验结果表明,采用这种新工艺可以使铝合金板料的拉深成形高度提高到传统方法的2.16倍。     

变薄拉深过程的数值模拟

利用上限元法对变薄拉深过程进行了数值模拟。在考虑加工硬化的基础上分析了凹模、芯轴与制件之间的摩擦因子以及变形比对变薄拉深工艺过程的影响。     

汽车保险杠拉深成形数值分析与工艺优化

针对本公司生产的汽车保险杠,结合实际工作状况,使用Dynaform钣金有限元分析软件进行了冲压成形过程的数值模拟分析.通过计算机仿真技术基本揭示了零件变形过程的塑性变形规律,理论计算结果与实际成形结果相一致.在此基础上,利用数值模拟技术手段,分析不同压边力条件下零件成形质量.计算结果显示,压边力为1100 kN时成形质量最佳,实际参数调整也说明了这一点.数值模拟技术的应用有助于优化参数、改进工艺,从而提高冲压产品质量,对指导生产具有实际应用价值.     

Development of an automated process sequence design system for multistage elliptical-Shaped deep drawing products

This study defined the cross-section consisting of a round in the major axis and a straight line in the minor axis for deep drawing product as elliptical. A process sequence design for elliptical-shaped deep drawing products was diversely proposed according to shape, dimension, and specification of products. This study presents two approaches to the design of a preform, a key process for elliptical-shaped products: using a punch with a circular cross-section, and for geometrical similarity of the intermediate process cup and final product, using a punch with a cross-section similar to that of the oval-shaped cup. In addition, blank shapes for elliptical-shaped products were designed and verified with experimental results. In the study, production rules, which play important roles in an automated process sequence design system, based on two approaches mentioned above and blank design, were generated for elliptical-shaped deep drawing products. The system developed on the production rules consists of a recognition module of input geometry, 3-D modeling to calculate surface area automatically, blank design, and a process planning module. Improving productivity and reducing time and cost would prove to be very useful.     

DT3外壳拉深工艺的改进

针对DT3外壳拉深过程中出现的问题,从拉深工序安排、模具加工工艺及润滑几个方面给出了改进措施,大大缩短了生产周期,降低了生产成本,明显改善了产品的外观质量和模具寿命。     

微拉深成形工艺及模具设计研究

利用实验研究和数值模拟分析相结合的方法来研究厚度为0.2 mm以下纯铜薄板的微拉深成形工艺及模具设计.通过一系列几何尺寸相似的杯形件的微拉深实验获得实验数据-成形力曲线;利用数值模拟研究了摩擦系数μ、相对模具间隙C/t和相对凹模圆角半径Rd/t对最大成形力的影响.研究表明,对最大成形力而言,摩擦系数μ的影响最为显著,而相对模具间隙C/t和相对凹模圆角半径Rd/t的影响在制造误差范围内不明显.在考虑摩擦条件的尺度效应的情况下,无量纲设计方式是一种比较有效的微拉深工艺及模具设计方法.     

用AutoCAD确定拉深工艺的系统开发

介绍了基于VB6.0运用数据库与参数化相结合的方法,在Auto CAD2000中拉深工艺的参数化设计及出图的开发过程.系统运行时,只要输入零件尺寸数据就可以完成整个工艺设计过程,最后输出工序图、各个工序参数.     

Experimental device for tribological measurement aspects in deep drawing process

The purpose of this paper is to improve strip drawing test in order to simulate sheet/tool contact conditions during a stamping operation. An original multi-pass strip drawing test in cylinder/sheet/cylinder contact geometry is presented and we emphasize the influence of certain factors rarely taken into account in the experimental simulation. In particular, we present examples where the bulk plastic deformation and the tools average temperature influence the level of friction and the sheet surface asperities flattening. To try to readjust the friction evolutions with the modifications of surface microgeometry, the tribometer is equipped with various measurements of relative sheet/tool displacement, including or not the stiffness machine and the stiffness of the contact. This was made possible by a potentiometric measurement where the tool plays the part of potentiometer and sheet that of the track, coupled to a measurement using a LVDT sensor.     

新型液压—机械拉深模与工艺过程数值模拟

介绍一种新型液压—机械拉深模装置,液压力能在拉深过程中形成径向推力、摩擦保持及流体润滑效应,建立与新型液压—机械拉深模相应的数值模拟模型,通过添加节点力和单元力来实现径向推力和凹模腔压力建模。用建立的模型,设置与实际试验相一致的工艺参数,对08Al拉深钢板进行数值模拟计算,将模拟计算结果与实际实验结果进行对比,说明径向推力和凹模腔液压力建模的正确性,为进一步进行液压—机械拉深工艺研究奠定基础。     

钼在深拉深时产生开裂原因初探

钼在深拉深过程中,极易产生横向开裂和纵向开裂。通过钼在拉深过程中的受力分析,初步探明了零件产生开裂的原因。通过试验,提出了有关的解决措施,并在生产中得到了验证,钼件拉深开裂问题基本上得到了解决。     

热水器封头零件拉深工艺研究

由于热水器封头顶部曲面形状,其拉伸工艺参数只能通过反复的试验才能确定,费工费力。应用有限元Dynaform软件对热水器封头的拉深工艺进行了有限元分析,研究了压边力、拉延筋设置、毛坯尺寸等参数对热水器封头成形质量的影响规律;针对原工艺的不足,提出了采用小尺寸毛坯和环形半圆形拉延筋改进的新工艺方案。它能显著降低压边力、提高拉深件的可成形性和成形质量,同时也能提高材料利用率。     

Occurence of strain path changes in a two-stage deep drawing process

This work is dedicated to the influence of the strain path change on the prediction of the deep-drawing of cylindrical cups. The aim of this work is to highlight the influence of the hardening model on the numerical prediction of the applied punch load, in the case of the 1999 Numisheet benchmark of the reverse re-drawing of cylindrical cups. The forming process consists in drawing a circular blank into a cylindrical cup in two stages, firstly in one direction and then in the opposite one. Three-dimensional numerical simulations of the process were performed using the Hill’s 1948 yield criterion associated with three different hardening laws: a purely isotropic hardening, a mixed hardening with both isotropic and non-linear kinematic contributions and a dislocation-based hardening model, which takes into account transient behaviors recorded during strain path changes. The experimental setup is presented as well as results obtained with a mild steel. Numerical simulation results obtained with the three hardening models are compared with experimental ones. It is shown that there is a significant influence of the hardening model in the second stage, when important strain path changes occur during the process.     

Analytical and experimental analysis of deep drawing process for bimetal elements

The paper presents the concepts of solving of deep drawing process for bimetal elements of sheet materials. The inertia forces, plastic hardening behaviour of the deformed material and dynamic stress are utilized in the problems of plasticity. The experimental results and general conclusion are presented at the end of the paper.     

A developed process for deep drawing of metal foil square cups

Deep drawing of non-axisymmetric cross-section cups from thin sheets or metal foils has become increasingly important, especially for miniaturization of mechanical components. However, with a thin sheet thickness, conventional deep drawing processes are not able to offer reasonable drawing ratios due to early formations of localized wrinkling and fractures at cup corners. In this paper, a friction aided deep drawing process has been developed to increase the deep drawability of thin sheets and metal foils. Productions of square cups have been chosen to verify the current proposed process since the shape provides recognizable non-homogeneous deformation, which can then be compared to conventional processes. In the proposed process, a circular blank holder of a square hole is divided into eight identical segments of 45°. During the deep drawing process, four of the eight segments will move radially inward while the other four segments will move radially outwards cyclically under a pre-determined blank holding pressure. A finite element model of the technique was used to simulate virtual experiments to evaluate and optimize the controlling parameters that influence the cup height and forming process. Taguchi and Pareto ANOVA statistical methods were subsequently used to determine the optimum conditions for best cup height. The results have shown that the new technique is capable of producing deep square cups from soft aluminum sheet (Al-O) of 0.5 mm thickness with a high drawing ratio of 3.3. In addition, it was also observed that the radial displacement was the most significant parameter in influencing the cup height.     

Investigation into wall wrinkling in deep drawing process of conical cups

Wrinkling phenomenon has been one of the major limiting failure modes in sheet metal forming processes. Wrinkling phenomenon in sidewall area of the cup formed in the conical cup test was considered both experimentally and numerically. A new deflection function is developed in this research and the effects of material anisotropy on the onset of wrinkling are studied using Hosford and Hill-1948 yield criteria under isotropy, normal anisotropy and planar anisotropy conditions. It was observed that application of Hosford yield criterion resulted in better prediction of wrinkling onset. It was also found that as the effective stress increases, consistency between predicted results and experimental data at the onset of wrinkling improves. Also, a good agreement between experimental data and predictions using proposed deflection function is obtained.     

板料成形过程中工艺辅助面的设计与优化(英文)

板料成形过程中工艺辅助面对成形件质量有着重要意义 ,但其设计非常费时 ,并且需要根据实验和数值模拟不断修正。本文提出一种工艺辅助面设计优化的方法。根据预期的工件形状 ,CAD软件会自动生成具有一阶连续的工艺辅助面。这些辅助面由 4个几何参数确定并且在随后的优化中将其作为设计变量。有限元网格划分在有用工件和初始辅助面上 ,在优化过程中将这些网格映射到改变了的工艺辅助面上而不需要重新划分网格。优化过程中采用可行域二次序列规划算法 (FSQP) ,并采用两个目标函数 :第一个是厚度函数 ,以使工件厚度变化最小 ;第二个是表面质量目标函数 ,以避免工件外表面的擦伤。FSQP算法和我们的快速逆法成形求解器相结合而得到一个高效的优化程序。本文提出的辅助面设计优化方法在方盒件和减震器罩上得到了成功的应用。     

铝合金2A12-O的动态充液拉深

针对铝合金板材成形性差的特点,提出液体内向流动动态充液拉深新技术。采用铝合金2A12-O板材对成形过程进行了初步实验验证后,运用有限元方法探讨不同的径向压力和不同的预胀路线对成形零件壁厚分布的影响。结果表明,采用该方法可以显著提高铝合金2A12-O的成形极限,成功拉深出拉深比达2.85的杯形件;径向压力显著影响杯形件壁厚的分布,通常较大的径向压力下的壁厚也较大。     

Analysis of punch velocity dependent process window in micro deep drawing

Micro forming is an appropriate technology to manufacture very small metal parts, in particular for bulk production, as they are required in many industrial products resulting from micro technology. Deep drawing provides a great application potential for the manufacturing of parts with complex shapes, even in very small dimensions. Concerning the so called size effects micro deep drawing is widely investigated. However, this process is carried out usually under laboratory conditions with a relatively low punch velocity, for example 1 mm/s. At the same time, the light weight of the forming tools for micro deep drawing makes it possible to vary the punch velocity in a relatively large range. Furthermore, raising the punch velocity is very meaningful for mass production in industry. Thus micro deep drawing with the punch diameter of 1 mm was performed with different punch velocities (1, 10 and 100 mm/s) in this work, whereby the process behaviour, especially the experimentally acquired process window changes with variation of punch velocities. The analysis in this work shows that the velocity dependent friction coefficients are responsible for the difference in process windows under different punch velocities.     

Wear behaviour in a combined micro blanking and deep drawing process

A one stroke micro blanking and deep drawing process is used to produce micro cups in a high quantity (200 strokes per minute) with an outer diameter of 1 mm. For cutting and deep drawing one single hollow punch is used. The outer diameter punches the circular blank while the inner diameter serves as drawing ring. Investigations regarding the tool life show that the punching edge wears out quicker than the rest of the tool. Furthermore it is shown that the positioning of the tool has a high influence on the wear behaviour.