轧制工艺对热轧钨板材组织和性能的影响

比较了一火一道，一火两道和一火三道的热轧工艺制度对钨板材质量的影响，结果表明：采用传统的一火一道工艺轧制的板材无开裂，工艺可靠，但板材纤维组织粗大，有部分再结晶组织出现，切削和磨削过程中出现掉渣现象；采用一火两道工艺轧制时，通过减少两道次轧制之间的时间，可以充分保证板材轧制温度和塑性，轧制的板材中纤维组织细小均匀，保留部分亚晶粒组织。通过适当延长板材最终退火时间可提高后续加工性能；采用一火三道次轧制时，板材加工温度明显降低，加工后出现明显的边裂，加工性能明显降低。因此，可以采用一火两道次工艺轧制磨光钨板材，从而实现加工工艺的优化。     

金属板材数控渐进成形加工轨迹交互修改及优化

金属板材数控渐进成形技术，是一种利用快速原型分层制造的思想对金属板材进行逐层挤压而成形金属覆盖件的柔性加工技术。本文介绍了金属板材数控渐进成形技术的过程、原理，同时，主要针对加工过程中发生的破裂、凹陷等缺陷，提出了一种基于NURBS的加工轨迹人机交互修改和优化的方法，解决了复杂曲面零件无法加工的难题，实现了金属板材数控渐进成形加工过程的快速响应。     

大型钛合金板材恒压砂带磨削自适应控制

针对大型钛合金板材磨削过程中存在的问题,研究了自适应控制技术在平面砂带磨床恒压随型磨削加工钛合金板材中的应用,在分析平面砂带磨削加工过程的基础上,建立了系统控制对象数学模型,设计并采用自适应控制技术应用于控制磨削加工.结果证明,所应用的自适应控制技术能较好的保证恒压磨削,有效地提高了钛合金板材表面深度尺寸精度.     

大规格纯钽板材的试制

钽具有高熔点、耐腐蚀、加工性能好等特点,广泛应用于化工、电子、航空航天等领域。国内生产钽合金板材的生产由于受设备和技术的限制,目前只能生产宽度小于1000 mm,长度小于2000 mm的板材。小尺寸板材会造成使用过程中产生焊缝较多的现象,易使其在长期使用过程中出现破裂失效的情况,造成较大经济损失。本文主要完成了大尺寸纯钽板材的试制工作,摸索了大尺寸纯坦板的制备工艺,制作出了宽幅达1300 mm,长度大于2000 mm的大规格钽板,解决了生产大尺寸纯钽板材的加工技术问题。     

金属板材数控渐进成形技术及加工轨迹坐标对位研究

金属板材数控渐进成形技术，是一种通过三轴数控成形机对金属板材进行逐层辗压而成形工件的柔性加工技术。本文探讨了金属板材数控渐进成形技术的过程、原理，同时，为了有效地排除成形过程中坐标对位对零件上出现的拉裂、材料堆积、材料硬化等现象的影响，本文提出了一种基于机器视觉的非接触式加工轨迹坐标对位方法，完成了金属板料数字化渐进成形中支撑模型的非接触式高精度快速定位。     

16MnDR复合板开裂原因浅析

文章通过研究试样的低倍、高倍组织及能谱分析结果表明16Mn DR复合板中存在较多硫化物、氮化物夹杂及未能轧合的显微疏松。基体板材存在放射网状细小裂纹,且基体板材内含有较多硫化物及大颗粒铌的碳氮化物夹杂;板材中心偏析加剧了裂纹的扩展大颗粒的铌的碳氮化物在板材受力变形中成为应力集中点造成板材加工开裂。优化造渣工艺提高钢液纯净度,最大程度降低钢液中硫、磷等元素含量,在连铸坯浇筑过程中采取保护性措施,避免钢液二次氧化,优化连铸工艺减少板材心部偏析,可以有效规避16Mn DR复合板加工开裂。     

基于多特征模型加工的数控渐进成形轨迹

针对多特征模型的不同数控渐进成形加工方式的问题,分析了基于层优先轨迹的加工方式与基于特征优先轨迹的加工方式,并对比了两种加工方式的优劣之处。采用有限元分析软件ANSYS对两种加工方式下板材的成形过程进行模拟,有限元分析结果表明:基于特征优先轨迹下的数控渐进成形方式的效率比基于层优先轨迹下的数控渐进成形方式高20. 7%,另外,基于层优先轨迹加工方式下板材成形后的最小厚度值也比基于特征优先轨迹加工方式下板材成形后的最小厚度值要略大。但基于层优先轨迹下成形后板材的轮廓相对于基于特征优先轨迹下成形后板材的轮廓,其更加接近于设计件的轮廓。     

汽车弯曲纵梁板加工CAD/CAM集成的研究与应用

介绍了在汽车弯曲形纵梁板加工中,应用网络和CAD／CAM技术构成柔性加工系统,以及Pro／E、AutoCAD、Apns98、ProCAM软件从板材的CAD三维图、二维图到生成数控加工程序的过程。     

三辊滚弯成形过程的回弹研究与试验分析

回弹是板材滚弯成形过程中一种不可避免的现象,直接影响着板材的加工精度。为了提高三辊卷板机板材回弹后的成形质量,建立了三辊回弹理论模型,预测了板材回弹后的滚弯成形半径;利用ABAQUS仿真软件分析了滚弯变形区的应力场分布,分析了上辊下压量、轧辊与板材间的摩擦力以及多道次滚弯成形对板材回弹的影响规律;通过多道次滚弯试验进行了验证。试验结果表明:随着上辊下压量和摩擦系数的增大,板材回弹量的下降趋势逐渐趋于平缓;多道次滚弯加工降低了板材回弹时的波动,提高了回弹均匀性,板材的成形质量随之提高;相较于多道次滚弯试验,三辊回弹理论模型的最大误差为8.4%,有限元模型的最大误差为6.7%,都具有较高的精度。     

钣金加工柔性系统的立体仓库管理和监控的设计应用

以板材加工柔性系统为背景,详细介绍了柔性系统中立体仓库控制管理系统,重点论述了自动化板材立体仓库的功能结构、出入库、监控和码垛管理、及单元通讯技术和方式等.对在板材加工和其他制造业中推广和应用自动化立体仓库技术具有借鉴意义.     

基于PAM-STAMP2G的回弹自动补偿功能的模具设计

回弹是钣金零件成形过程中很常见的现象,并直接影响产品质量,传统解决回弹的方法是采用"试错法"来解决模具回弹补偿问题。文章提出了基于PAM-STAMP2G回弹自动补偿功能的模具设计方法,以解决模具回弹补偿问题,并通过一个叶片零件回弹自动补偿问题,验证了此回弹自动补偿方法的正确有效性。     

应力对铁磁构件磁畴组织的影响

地磁场环境中受载荷作用的铁磁试件,其内部会发生具有磁致伸缩性质的磁畴组织定向和不可逆的重新取向。利用Bitter粉纹法观察了未经磁化、受力程度不同的无取向硅钢片和20号钢试件的磁畴结构,对比分析了应力对磁畴的影响。结果表明:无取向硅钢片和20号钢试件在未受力或应力集中较小时,晶粒内磁畴以180°畴、树枝状畴和剑状畴为主,同一晶粒内畴壁相互平行;随着应力集中程度增加,畴壁长度和间距发生改变,出现了迷阵畴Ⅰ型和迷阵畴Ⅱ型,且应力集中程度越大,迷阵畴的数量越多。     

板料冲压成形仿真质量控制研究与应用

通过成形过程中的动能和内能判断仿真是否符合准静态成形要求,采用正交试验得到最佳的仿真参数,通过试验验证考查能量和正交试验相结合的方法能否得到高质量的仿真结果,结果表明该方法在板料冲压成形仿真质量控制中可行。     

Rigid-plastic finite element analysis of plastic deformation of porous metal sheets containing internal void defects

Using rigid-plastic finite element DEFORM-2D and -3D software, this study simulates the plastic deformation of metal sheets at the roll gap during the sheet rolling process. The study focuses specifically upon the deformation of porous metal sheets containing internal void defects. The present numerical analysis investigates the relative density distributions, the void closure behavior, the deformation mechanisms and the stress–strain distributions around the internal voids for various rolling conditions. The influences on the dimensions of the final void of the thickness reduction, the initial internal void dimensions, the friction factors and the relative density are systematically discussed. The critical rolling conditions also investigated. A series of sheet rolling experiments are performed in order to verify the validity of the simulation results. The current numerical results provide a valuable source of reference for the design of pass schedules for porous metals undergoing rolling processes.     

铝锌高阻尼板材的内耗特征

论述了Ａｌ－Ｚｎ高阻尼合金板材在不同工作状况（温度、振幅、频率）条件下的内耗特征，同时还与纯铝板的内耗进行了比较。     

Development of a new sheet deposition type rapid prototyping system

Sheet deposition type rapid prototyping systems have many advantages: high build speed, low operating cost, large part size, no phase change, no need for support generation, etc. However, those sheet deposition type rapid prototyping systems generally require an additional post-processing step to remove excessive material. This post-processing step is generally time-consuming and labor-intensive as well. Especially, in case of parts with hollow cores and internal cavities, the removal of excessive materials can be an extremely demanding task.A new sheet deposition type rapid prototyping system that can minimize the post-processing is proposed. In the proposed system, the sheet is cut in two steps: the first before the shielding paper is peeled off and the second after peeling-off. The excessive area is removed during the peeling-off process after the first cutting. In this way, this system can reduce the post-processing time and cost as well as the limitation on the feasible geometric shapes compared to the conventional sheet deposition type systems.     

面向虚拟装配的工艺卡片动态生成技术的研究

工艺卡片的生成是虚拟装配系统的后处理部分。文章针对目前大部分虚拟装配系统中的工艺卡片生成功能所存在的工艺卡片样式不易修改的问题,深入分析了装配工艺信息的结构,并利用XML技术和Web技术研究开发了面向虚拟装配的工艺卡片动态生成系统。该系统将工艺卡片样式以XSL文件形式保存,当用户调用装配工艺卡片时,才从虚拟装配系统底层数据库提取装配工艺信息动态转换成XML文件,并加载相应的XSL样式文件,以WEB形式向用户提供装配工艺卡片,从而使得工艺数据与工艺卡片样式彻底分离,工艺卡片样式的修改可以只通过修改其相应的样式文件轻松完成,提高了虚拟装配系统的通用性。     

Effects of centerline macrosegregation on necking of P-added extra low carbon steel sheet

Effects of centerline macrosegregation on necking was examined by the stretching experiment for cold rolled P-added extra low carbon steel sheets. The centerline macrosegregated zone containing high concentration of Mn and P was elongated in the rolling process. The elongated macrosegregated zone induced instability in the strain state when the sheet was stretched, thus resulted in the waved sheet surface. The formability of cold rolled steel sheet was deteriorated due to the wave formed by the macrosegregation. The waved surface was thought to be caused by the higher hardness in the macrosegregated zone compared to the segregation free zone. The experiments on the stretching of sheet including macrosegregation showed that the macrosegregation was the important source of instability in that of the cold rolled steel sheets. A 3D FEM analysis was carried out for the quantitative evaluation of waved surface. It was confirmed that the main source of the waved surface was the macrosegregation. Stretching in the transverse direction under the plane strain condition made the cold rolled steel sheet more inhomogeneous than stretching in any other strain condition. The thickness difference in the stretched sheet was linearly increased when the ratio of hardness in the macrosegregated zone to that of the segregation free zone was increased. The macrosegregation formed in the internal crack close to the surface was more harmful to the formability in the cold rolled steel sheet than the centerline macrosegregation.     

Finite element modelling of resistance spot welding of aluminium with spherical tip electrodes

Abstract

A FEM based simulation model of the resistance spot welding process has been developed. The current simulation accounts for the non-uniform current density distribution in the sheet-electrode geometry and the elastoplastic deformation of the sheet due to electrode force, especially with spherical tip electrodes, since these effects are driven by and contribute to the main heat transfer analysis, which is governed by the internal heat generation within the sheet-electrode geometry as well as along the contact surfaces. The latent heat of transformation during melting or solidification, the variation of sheet/sheet contact resistance with temperature, and temperature dependent thermophysical material properties have been incorporated. The model also calculates the local time-temperature history of the sheet-electrode geometry that can be coupled with appropriate metallurgical reactions to determine metallurgical changes and subsequent mechanical properties in both the fusion zone and the HAZ.     

板塑性屈曲的变分原理

在金属板料塑性成形加工中 ,起皱是常见的 ,它影响成形件质量 ,预测与防止起皱已成为人们长期以来关注的热点问题。起皱实质上是金属板料的一种压缩不稳定现象。本文把板料塑性屈曲前后的材质状态视为刚塑性 ,板材塑性皱曲时 ,所满足的全部方程 :平衡 ,机动 ,屈服及流动定律 ,归结为一个泛函的求极值问题 ,在这个泛函中 ,内力场与速度场是彼此独立的自变函数。用直接法可以方便地求得金属板料塑性屈曲问题的近似解析解。文中以环缺在边界纵向拉压力作用下的皱曲问题为例 ,具体地给出了皱曲载荷及板的内力及速度场形态