TD覆层处理技术在解决冲压件拉毛中的应用

汽车冲压件在成形过程中很容易出现表面的拉伤问题,如继续生产,模具的表面也会出现拉伤,生产出的制件易造成制件报废或返工返修,即增加单件的成本又增加了模具维护的成本.通常解决问题的方法是停机对模具表面进行修磨、抛光,但容易造成模具凸凹模间隙变大,产品品质降低.因此就如何解决制件拉伤问题问题展开了系统的分析,重点对其中一个解决方法-模具表面TD覆层处理进行详细说明.     

薄板成形中模具硬度对拉毛影响的实验研究

借助带拉深筋的盒形件拉深工艺,模拟高强度钢板成形中的覆盖件表面拉毛行为.用表面粗糙度Ra和最大划痕深度H来定量评价冲压件拉毛程度.实验研究表明:随着拉深次数的增加,Ra值和H值越来越大,并且在成形前期和后期其数值增长速度较快;同时,Ra值和H值随模具硬度的降低而增大,即模具的硬度越低,越易于产生拉毛缺陷.     

冲压制件起皱、开裂分析与改进

随着汽车行业的飞速发展,汽车产量不断提高,而汽车零部件在冲压生产过程中产生的各种缺陷造成制件报废．不仅提高了制造成本,而且造成了原料浪费。本文针对汽车冲压件生产过程中出现的各种缺陷进行分析,发现起皱与开裂问题造成制件报废的数量占报废制件总数的绝大部分．通过解决制件开裂与起皱问题．可以有效降低制件报废率．节约生产成本。     

磨边机振动原因分析与解决方法

分析引起磨边机低频微幅振动的影响因素.在单一影响因素条件下,利用万分表对磨边机在低速运行下的振动进行多次测试,分析影响机床低频微幅振动的所有影响因素,建立影响因素的振动方程；找出引起振动的主要影响因素,提出消除磨边机低频微幅振动的方法,为高精度磨边机的振动分析提供理论依据和解决方法.     

侧围外板表面畸变原因分析及解决方法

针对某汽车侧围外板上边梁外观面畸变的问题,对零件结构及成形工艺进行分析,并利用Auto?Form有限元分析软件对零件成形过程进行仿真,分析结果表明,上边梁附近的结构起伏急剧导致成形过程中应变分布不均和成形后残余应力释放不均是造成零件外观面畸变的根本原因。通过在拉深工序中优化工艺补充和调整拉深筋阻力,结合零件成形时利用强压技术,有效解决了零件表面畸变缺陷问题。     

非正弦振动台颤动原因分析与解决方法

对钢厂的电动非正弦振动台在测试中出现颤动和不平稳现象的根本原因进行了分析,得出此钢厂振动台受振机构的固有频率低,装配时安装精度低和某些零部件出现磨损和损坏等是振动台出现颤动和不平稳现象的根本原因。提出提高受振机构的固有频率和减少产生共振的振源是解决颤动问题的根本方法。ANSYS分析得出加厚板簧能够达到提高受振机构固有频率和使其不容易出现颤动现象的目的。     

扭力轴同步折弯机滑块爬行原因分析与解决方法

介绍了在工程实践中出现的扭力轴同步折弯机滑块工进爬行现象,分析了滑块爬行原因和解决方法,针对扭力轴折弯机普遍存在的爬行问题,提出了全面系统的综合预防措施。     

薄壁盒形容器零件拉深起皱的原因分析与解决方法

各种薄壁盒形容器拉深零件在拉深过程中经常出现起皱现象,特别是对带有锥度的方形容器和带有阶梯的矩形容器等异型类零件的起皱现象,一直是在拉深模具设计中十分关注的问题.这些问题与拉深模具本身的设计参数有着直接的关系,也与拉深模具的制造参数与模具装配、调试有着直接的关系.     

电池负极盖精密级进模跳屑原因分析与解决方法

以LR6与LR03类碱性电池负极盖精密级进模为研究对象,针对端子类或小五金类冲模成形速度提升时出现的跳屑问题进行了研究,找到了一些解决方法,可为类似零件的精密级进模设计提供一定的参考。     

高强度钢板温成形回弹规律实验研究

高强度钢板冲压成形后的回弹问题是其应用中的主要问题之一.温成形技术可显著改善高强钢的成形性.以-U形件为研究对象,通过改变成形温度及压边力,对DP590双相高强度钢在温成形工艺下的回弹和由其引起的扭曲进行了研究.研究表明:随着温度和压边力的增加,制件的回弹逐渐减小,但温度的改变对于扭曲无较大影响,压边力的增大可改善扭曲现象.     

Numerical and Experimental Investigation into Hot Forming of Ultra High Strength Steel Sheet

Hot forming of ultra high strength steel (UHSS) sheet metal grade 22MnB5 boron for channel components using water cooling is studied on a laboratory scale. After hot forming, the different microstructures such as martensite, bainite, and pearlite in formed component are produced, which are closely related with mechanical properties of formed component. The effect of forming start temperature and the contact state between blank and die on the microstructure evolution is investigated. In addition, the effect of processing parameters, such as forming start temperature and blank holder force (BHF), on the final quality of component, i.e., springback, that happens after hot forming of UHSS is investigated. It can be concluded that the forming start temperature has a significant effect on the final mechanical properties of formed components. The effect of forming start temperature on springback is examined in detail under a wide range of operating conditions. The higher the BHF and the forming start temperature, the lower is the springback after hot forming. Furthermore, thermo-mechanically coupled finite element analysis model encompassing heating of sheet blank, forming and quenching are developed for hot forming process. The stress distributions on sheet blank under different conditions during hot forming are compared to gain a fundamental understanding of the mechanism of springback. Comparisons show that numerical simulation results have good agreement with experimental results.     

Modeling and FE Simulation of Quenchable High Strength Steels Sheet Metal Hot Forming Process

High strength steel (HSS) sheet metal hot forming process is investigated by means of numerical simulations. With regard to a reliable numerical process design, the knowledge of the thermal and thermo-mechanical properties is essential. In this article, tensile tests are performed to examine the flow stress of the material HSS 22MnB5 at different strains, strain rates, and temperatures. Constitutive model based on phenomenological approach is developed to describe the thermo-mechanical properties of the material 22MnB5 by fitting the experimental data. A 2D coupled thermo-mechanical finite element (FE) model is developed to simulate the HSS sheet metal hot forming process for U-channel part. The ABAQUS/explicit model is used conduct the hot forming stage simulations, and ABAQUS/implicit model is used for accurately predicting the springback which happens at the end of hot forming stage. Material modeling and FE numerical simulations are carried out to investigate the effect of the processing parameters on the hot forming process. The processing parameters have significant influence on the microstructure of U-channel part. The springback after hot forming stage is the main factor impairing the shape precision of hot-formed part. The mechanism of springback is advanced and verified through numerical simulations and tensile loading-unloading tests. Creep strain is found in the tensile loading-unloading test under isothermal condition and has a distinct effect on springback. According to the numerical and experimental results, it can be concluded that springback is mainly caused by different cooling rats and the nonhomogengeous shrink of material during hot forming process, the creep strain is the main factor influencing the amount of the springback.     

Analysis of Dynamic Loads on the Dies in High Speed Sheet Metal Forming Processes

During high-speed sheet metal forming processes, the speed at which the work piece contacts the die tooling is on the order of hundreds of meters per second. When the impact is concentrated over a small contact area, the resulting contact stress can compromise the structural integrity of the die tooling. Therefore, it is not only important to model the behavior of the workpiece during the high-speed sheet metal forming process, but also important to predict accurately the associated workpiece/tooling interface loads so that engineers can more confidently propose robust die tooling designs. The foundation to accurate predictions of contact stress on die tooling is a reliable contact model within the context of a finite element simulation. In literature, however, there exists no comprehensive guideline for establishing a contact model for high-speed sheet metal forming processes using the finite element method. In this paper, mathematically justified contact model recommendations are offered for the electrohydraulic forming (EHF) process.     

薄板坯连铸连轧700 MPa高强度钢板的开发

文章介绍了本钢薄板坯连铸连轧700 MPa级冷成形用高强钢的成分设计及热轧工艺设计、组织控制及力学性能检验等。通过合理的成分及轧制工艺设计,得到理想的组织形态,保证其高强度的同时又兼具良好的低温冲击韧性及冷成形性能和焊接性能,产品广泛应用于改装车底梁、起重机吊臂等工程机械领域。     

LS-DYNA在板料成形仿真中的应用

讨论了LS-DYNA自适应方法在板料成形分析中的一般过程；基于LS—DYNA的板料成形有限元分析分为前处理、求解和后处理；前处理设置单元属性、构建模型、划分网格、定义接触、初始条件、载荷及约束、求解时间和输出文件等。再用LS—PREPOST查看结果，动画模拟过程，得出能量、应力等变化曲线。并以板料的半球件成形为例进行了分析和验证。     

电磁成形技术在薄板成形中应用的研究进展

电磁成形技术是一种高能、高效成形技术,目前已在工业生产中获得广泛应用,是近年来一种新兴的板材塑性加工方法.本文从理论、试验和有限元仿真3个方面介绍了国内外电磁成形技术运用于薄板成形领域的最新成果,主要阐述了管件缩径成形和胀形成形、平板成形以及薄板校形方面的研究进展,讨论了在应用研究中存在的问题和进一步发展方向.     

高强阻尼铝合金轧制板材的组织与性能

采用气体雾化/粉末冶金（RS P/M）工艺研制Al-9.0Zn-2.5Mg-2.0Cu-0.1Ni-0.1Zr/Zn-30%Al（LZ7）高强阻尼铝合金,经挤压、轧制成5.0 mm板材。详细观察LZ7板材轧制和双重时效（T7态）两种状态下的组织,并测试了T7态室温拉伸性能和阻尼性能。结果发现：采用快速凝固气体雾化制备的LZ7合金主要强化相有η′相和η相;LZ7金属基复合材料具有较好的阻尼性能,室温-250℃,LZ7合金的阻尼性能为6.0×10-3-24.52×10-3;室温下：0σ.2〉465 MPa,σb〉490 MPa,5δ〉6.0%。     

Analysis of Residual Stresses in High-Pressure Sheet Metal Forming

The further development of innovative forming processes like sheet metal hydroforming is only possible with the help of detailed knowledge about the workpiece properties and their formation depending on the particular process strategy. Up to now, the detailed understanding regarding the formation of residual stresses in hydroforming processes like the high-pressure sheet metal forming (HBU) is insufficient. Therefore, numerical (FEM) and experimental investigations on the residual stresses induced in HBU-formed workpieces have been carried out. The results show that a higher fluid pressure leads to significantly lower residual stresses in addition to an improved accuracy of form and dimensions.     

预冲工艺孔的板料冲压成形性分析

利用有限元数值模拟技术对预冲工艺孔的板料的冲压成形性进行了分析,得出了工艺孔附近区域坯料的冲压成形的特点及应力、应变的变化趋势.