薄壁钢筒温成形模具磨损规律及机理

目的通过对薄壁钢筒温成形过程进行数值模拟,分析其磨损规律及机理。方法采用Deform-3D对薄壁钢筒的温挤压过程进行模拟,分析在不同挤压速度和模具预热温度下,模具最大磨损量的分布规律。结果挤压速度越小,凸模顶端温度越高,磨损越严重;模具预热温度高于250℃时,模具表面氧化膜破坏,模具钢硬度急剧下降,模具磨损加剧。结论通过设置合理的工艺参数,可以减缓模具的磨损,并为模具表面修复提供了理论依据。     

分流模挤压非对称断面铝型材有限元数值模拟分析

采用了一种基于Deform-3D结合Pro/Engineer的对分流模挤压过程中焊合面相互穿透网格进行重构的技术,并对空心型材分流模挤压过程中金属的流动行为、温度场及模芯受力情况进行了模拟分析。结果表明,网格重构技术对于空心型材挤压的数值模拟具有可行性,可实现焊合面与对称面不一致(非流动对称面)空心型材的分流、焊合及成形的挤压全过程的仿真,从而为研究挤压全过程(尤其是焊合过程)的金属流动行为、模具结构的合理性、变形体的温度场分布情况、焊合阶段模具的受力等提供了一种新的计算分析方法。     

汽车外星轮亚热精锻成形工艺研究

提出汽车外星轮的亚热精锻成形工艺,与传统热锻工艺比较,具有简化工艺、节约能源的优点。并采用数值模拟方法,对汽车外星轮的亚热控制精锻工艺进行了深入研究。将通过热模拟实验研究确定的流变应力模型引入到有限元数值模拟软件中,对外星轮亚热精锻成形过程进行模拟,确定了外星轮亚热精锻的最佳工艺参数,获得了较好的效果。     

基于 Deform-3D 的车用下轴套零件冷挤压模具结构优化设计

目的分析挤压成形中车用下轴套零件成形表面出现的折叠缺陷,优化挤压上凹模的底部出口斜度、下凹模的入口斜度和挤压深度等主要成形工艺参数。方法采用DEFORM-3D软件,对汽车下轴套零件的冷挤压成形工艺进行了系统的有限元数值模拟试验。结果挤压成形模具结构设计不合理,导致在成形过程中模具分型面处金属出现汇流并形成折叠。结论通过优化挤压模具结构,使金属成形良好,无折叠缺陷出现,最终获得了较为合理的冷挤压模具结构。     

基于预锻成形腔的直齿圆柱齿轮冷挤压数值模拟分析

直齿圆柱齿轮冷挤压坯料在塑性成形过程中属于三维变形,由于变形复杂,带来成形压力大,填充困难及模具寿命低等问题.建立了基于流曲线和等截面理论的流线型预锻成形腔,通过刚塑性有限元软件对挤压过程进行了数值模拟.结果表明,流线型挤压腔符合金属流动规律,可有效提高金属坯料在角隅的填充能力,减少变形突变和成形压力.     

汽车万向节叉热挤压成形的数值模拟分析

采用刚粘塑性有限元法对万向节叉热挤压成形过程进行数值模拟分析,综合考虑了变形、热传导、变形生热、摩擦生热等多个因素,得出了成形过程中金属流动变化的3个阶段。研究了摩擦条件和终锻温度对成形力的影响,得出良好的润滑条件和给模具进行预热,能够有效的控制成形力,有利于金属的流动及提高模具寿命。     

复杂连接块成形工艺有限元分析及模具设计

目的采用理论分析、计算机有限元分析和物理实验的方法对某复杂连接块温挤压成形技术进行研究,根据有限元分析结果设计出模具并成形该零件。方法通过调节不同的参数,对该零件的成形进行数值模拟。结果有限元分析结果表明,该零件在成形过程中等效应力应变分布不均匀,两端凸台位置较难充填。结论根据以上分析结果,在设计模具和实验的时候,提高成形温度及成形速率,优化润滑条件,降低了成形载荷,并在实验室现有的1000 t液压机上进行了物理实验。实验结果与数值模拟结果相吻合,为该零件的批量化生产提供了指导。     

双凸模冷径向挤压十字轴的模拟

针对十字轴零件特征,设计了十字轴零件的一次性冷挤压成形工艺,基于有限元分析软件Deform-3D平台,对十字轴冷挤压成形过程进行模拟。通过有限元数值模拟,对十字轴挤压过程中金属径向流动、加载载荷变化、内部的等效应力分布等做了分析,为汽车十字轴零件的单道次挤压成形生产提供数值参考。     

模具在工件反挤压过程中的变形模拟研究

模具在金属塑性成形过程中起着十分重要的作用.就一般而言,模具在金属成形过程中的变形被忽略,将之视为刚性体.然而在金属精密成形中,模具的变形对成形件的尺寸精度将产生较大的影响.利用SuperForm软件针对模具在工件挤压过程中的变形进行了有限元数值模拟,对这一问题作了初步分析与探讨,为工厂实际生产的工艺制定、模具设计提供理论参考与依据.     

新能源汽车4032铝合金涡旋件背压成形数值模拟与实验研究

目的 探究新能源汽车空调压缩机涡旋盘静盘成形技术及成形过程,解决新型涡旋盘外圈充填不满的缺陷问题。方法 采用背压挤压与闭式挤压结合的工艺方案,利用有限元技术对成形过程进行数值模拟分析,然后结合物理实验对工艺可行性进行验证。结果 获得了成形过程中金属流动规律、载荷变化曲线、应力应变分布和实际成形样件,并将终锻过程分为3个阶段：第1阶段主要是成形涡旋基底;行程到达30%时进入第2阶段,第2阶段成形外圈和涡旋部分,外圈金属流动较涡旋部分金属流动更快,外圈成形完整;行程到达84%时进入第3阶段,成形涡旋的中间部分。终锻过程中,涡旋根部由于形变量较大,存在应力集中现象。终锻快结束时,外圈已经充满,顶部应力增大。结论 成形中预锻的外圈保证了金属的充填,成形完整,成形工艺可行,“两步法”成形可以获得质量良好的涡旋盘。     

Investigation of die radius arc profile on wear behaviour in sheet metal processing of advanced high strength steels

Advanced high strength steels (AHSS) are increasingly used in sheet metal stamping in the automotive industry. In comparison with conventional steels, AHSS stampings produce higher contact pressures at the interface between draw die and sheet metal blank, resulting in more severe wear conditions, particularly at the draw die radius. Developing the ability to accurately predict and reduce the potential tool wear during the tool design stage is vital for shortening lead times and reducing production cost. This paper investigates the effects of draw die geometry on the sheet metal tool wear distribution over the draw die radius using numerical and experimental methods. A numerical tool wear model is introduced and applied using the commercial software package Abaqus. Channel bend tests are carried out using an Erichsen sheet metal tester to verify the numerical model. Various geometries of radius arc profiles, including standard circular profiles, high elliptical profiles, and flat elliptical profiles, are numerically investigated, and the wear volume and contact pressure distribution along the radii are determined. The results show that the profile of the draw die radius has a significant effect on the wear distribution, and that a low contact pressure distribution can be achieved by using a combination of circular and high elliptical curved geometries.     

Ti–6Al–4V钛合金筋板类吊挂锻造成形工艺优化及模具磨损研究

目的 改善Ti–6Al–4V筋板类吊挂锻件成形缺陷,降低模具磨损。方法 通过对原始工艺中存在的折叠、充填不满等缺陷进行分析,揭示局部飞边高度对锻件充填的影响,进而优化终锻模具局部飞边高度;通过增加预锻件筋条等几何特征,对预锻模具结构进行优化设计,并分析塑性变形时筋条区域金属材料的流动情况。结合BP神经网络技术,分析锻造工艺参数对终锻模具磨损的影响,并对工艺参数组合进行优化设计。结果 基于局部飞边高度对锻件充填效果的影响规律,确定最佳局部飞边高度为4 mm;通过增加预锻筋条优化预锻件结构,从而有效避免折叠缺陷;将BP神经网络技术与数值模拟结合,得到了最优工艺参数组合,有效降低了锻造模具的磨损量。结论 通过实际锻造生产试验对模拟分析结果进行了验证,固化了最佳模具结构与工艺参数组合,获得了变形均匀且无工艺缺陷的钛合金发动机吊挂锻件。     

The failure analysis of a deep drawing die in the manufacturing of an automotive shock absorber cap

A deep drawing die, employed in the manufacturing of an automotive shock absorber endcap presented premature wear in a part of the region of contact with the blank. This led to unacceptable scratching and surface finish in the produced endcaps, resulting in an excessive scrap rate and undesirable finishing operations in order to repair the defects, when possible at all. Initially, the surfaces of parts produced in new and in worn dies were analyzed. The loads and strains in the endcap and in the dies were then evaluated, through a finite element analysis (FEA) utilizing the DEFORM 7.0 software. The validation of the simulation was performed comparing the experimental measurements of the part thickness with those supplied by the numerical simulation. The validated FEA model indicated an excessive pressure on the worn region, reaching unacceptable levels for the chosen die material. The solution to the failure would involve a change either in the die material, or in the process design, or in the die/blank lubrication.     

材料摩擦磨损分子动力学模拟的研究进展

随着新技术的发展以及材料服役环境的日益复杂化,传统的试验研究已经不能满足人们对摩擦磨损的认识需求,因此必须借助数值模拟方法来研究材料的摩擦磨损行为.特别是随着近年来原子尺度理论模型的不断完善和计算机运算能力的不断提高,分子动力学模拟已经成为研究材料摩擦磨损行为和机制的重要方法.本文详细综述了材料摩擦磨损分子动力学模拟的国内外研究现状.首先阐述了分子动力学模拟中势能函数的建立;其次介绍了材料摩擦磨损分子动力学模拟常用的接触模型;然后概述了采用分子动力学模拟方法研究接触面积、载荷、温度、速度和晶体取向等因素对材料摩擦磨损的影响;最后指出了目前材料摩擦磨损分子动力学模拟中存在的一些问题,并对未来发展方向进行了展望.     

航空叶片模具设计参数对模具磨损影响分析

为解决航空叶片精锻模具磨损严重,设计参数确定困难等问题,本文在分析模具设计过程和锻造工艺的基础上,基于Archard摩擦理论,借助有限元分析软件对不同设计参数的叶片模具的精锻成形过程进行了模拟仿真,运用正交试验设计方法分析了模具成形角度、桥部厚度、桥部宽度对叶片成形力和模具磨损的影响,得出了有益于叶片成形和减小模具磨损的最优化组合设计参数,并对该参数的计算方法进行了改进,简化了计算过程且参数计算更加精确;最后,通过工程实例对上述过程进行了验证,其实验结果与仿真结果的一致性较好,减小了模具磨损,提高了叶片模具设计效率.     

A DEM-based method for predicting the wear evolution of structural boundary composed of spherical boundary elements

In the discrete element method (DEM) simulation for wear prediction, structural boundary is now represented extensively by triangular meshes with high resolution, which brings a huge computational cost. A DEM-based method for predicting the wear evolution of structural boundary has been developed for computational efficiency. The structural boundary subjected to wear is represented by the spherical boundary elements in the DEM simulation in combination with the inside triangles and fitting curved surface in wear prediction. Wear prediction is performed through a series of evolution steps. In each evolution step, the collision energies by particles at structural boundary are collected via the DEM simulation and assigned to the boundary elements. Then, the volume losses of structural boundary are predicted across each relevant boundary element. Finally, the new geometry of structural boundary in response to wear is described by moving the boundary elements along the depths of wear individually. Through converting the contact detection between structural boundary and particles into between spherical boundary elements and particles, our method greatly reduces the computational cost in the DEM simulation. Through two numerical tests, our method has been verified to be an efficient and accurate method for the wear prediction of structural boundaries with different resolutions.     

Numerical study of contact conditions in press hardening for tool wear simulation

In the press hardening industry, industrial and academic efforts are being directed toward predicting tool wear to realize an economical manufacturing process. Tool wear in press hardening is a tribological response to contact conditions such as pressure and sliding motion. However, these contact conditions are difficult to measure in-situ. Furthermore, press hardening involves high temperatures, and this increases the complexity of the tribo system. The present work investigated the contact conditions of press hardening with a commercial FE code (LS-DYNA) as a base for tool wear simulation. A press hardening experiment was established in industrial environments and evaluated through FE simulations. The numerical model was set up so as to approximate the manufacturing conditions as closely as possible, and the sensitivity with respect to the friction coefficients was examined. The influence of numerical factors such as the penalty value and mesh size on the contact conditions is discussed. The implementation of a modified Archard’s wear model in the FE simulation proved the possibility of tool wear simulation in press hardening. Finally, a comparison between the tool wear simulation and the measured wear depth is presented.     

高强度钢板U形件热冲压凹模结构拓扑优化

为降低热冲压凹模的生产成本和使用成本,基于板料热冲压数值模拟对凹模结构进行了拓扑优化设计.运用有限元软件ABAQUS建立热力耦合有限元模型,对高强钢板U形件的热冲压成形和淬火过程进行了数值仿真.提取凹模与板料间关键工况下接触应力作为凹模拓扑优化的外在载荷,建立约束凹模结构关键区域节点位移的体积最小化拓扑模型,对热冲压凹模结构进行拓扑优化设计,最终实现结构减重20%,且优化后凹模的变形和应力与优化前的结果相差甚微.研究内容对热冲压过程数值模拟和模具结构拓扑优化研究具有一定参考价值.     

变速箱长柄法兰轴工艺分析及模具关键结构设计

目的 根据长柄法兰轴的结构特点,制定一套产品的成形工艺方案并投入到生产中。方法 法兰轴是双离合器变速器输出端与差速器连接的重要零件,其形状复杂,成形难度较大,根据产品的特点,制定温锻–冷锻联合成形的工艺方案。针对温锻工序中锻件内腔难以充满的问题,利用DEFORM对工艺中的关键步骤进行模拟仿真,并根据模拟结果对模具进行补偿设计,使锻件内腔底部与模具之间的间隙降至0.3 mm以下。考虑到金属的剧烈流动会加重模具的磨损,设计一套模具润滑系统,以提高模具的使用寿命。而锻造过程中模腔内形成密闭空间,压缩的空气会阻碍金属充填型腔,因此,在凹模与凸模上设计出一套模具排气系统,以避免塌角缺陷的产生。结果 实现了长柄法兰轴工件的工业化生产,生产效率可达每分钟12.5只。结论 根据数值模拟的结果对模腔面进行优化,设计了一套模具的润滑结构与排气结构,避免了锻造缺陷的产生,为双离合器变速箱长柄法兰轴产品的温冷锻工艺生产提供了经验依据。     

Lightweight near net shape components produced by thixoforming

Recent thixoforming development work at EFU has been concentrated on: (1) improved machine concepts for serial production, (2) die design and prototype manufacturing from various light metals including magnesium and metal matrix composites, (3) numerical simulation for process optimization, (4) accessing process benefits through the appropriate use of design options (specially designed steering knuckle demonstrator). A pilot thixoforming system consisting of four EFU heating modules with patented sensor systems, an ABB robot for billet handling and a Frech 5,8 MN real time controlled high pressure die casting machine has been used to produce various prototype parts. The process parameters have been examined with incomplete die filling experiments and numerical simulation. To exploit the full potential of the thixoforming process, a steering knuckle for a compact passenger car has been redesigned, thixoformed and tested. The weight of the new part is approx. 35% below that of a conventional forged steel design, despite identical functional capabilities. © 1997 Elsevier Science Ltd.