激光焊接参数对汽车用双相镀锌钢DP780焊接接头性能的影响

通过实验研究了激光功率、焊接速度对零间隙激光焊接汽车用双相镀锌钢D P780焊接接头性能的影响。焊接速度恒定时,焊接接头固化时间随着激光功率的增加而增加,大量锌蒸汽通过液态金属及气孔逸出,熔池内部锌蒸汽减少,焊缝内部孔隙度水平下降、气孔本身变小,焊接接头性能增加;激光功率恒定、焊接速度不同时,随着焊接速度的增加,焊接接头固化时间减小,锌蒸汽通过液态金属及气孔逸出的难度增加,大量锌蒸汽停留在焊接接头内部,造成焊件表面和焊接接头内部孔隙度增加,由于气孔的存在,工件机械强度减少,焊接接头的焊接性能随之变差。     

双向钢的活动筋过拉伸工艺及模具设计

对于高等级的双相钢成形,克服扭曲回弹是个难以逾越的关隘.本文介绍了一种带活动拉伸筋的过拉伸模,用于成形DP钢内板件,取得了较好的效果.它为突破超高强度钢的工艺瓶颈提供了重要参考.     

Numerical modeling of damage evolution of DP steels on the basis of X-ray tomography measurements

In order to couple the damage evolution and the stress state of DP steel grades, a new advanced GTN (Gurson-Tvergaard-Needleman) model was developed and implemented into a finite element code. This model is an extension of the original one. It takes into account the plastic anisotropy and the mixed (isotropic + kinematic) hardening of the matrix. Two different methods to compute the void volume fraction were developed and used within the constitutive equations. The first method is new and allows the accurate modeling of the observations of damage initiation and growth in DP steels measured using high-resolution X-ray absorption tomography ( [Bouaziz et al., 2008] and [Maire et al., 2008]). The second method is classic and assumes the additive decomposition of the total void volume fraction into a nucleation and a growth part. A parametric study is carried out to assess the effect of the kinematic hardening on some mechanical parameters such as the equivalent plastic strain, the triaxiality and the porosity. The numerical predictions are favorably compared to the experimental results.     

基于西门子数字驱动伺服611U 的钢轨锯钻床控制系统

近年来,我国铁路客运专线的建设得到高速发展,对钢轨质量提出了更高要求,对钢轨定尺的准确性和钻孔的质量要求也越来越高,通过采用西门子数字驱动伺服611U装置结合上位机PLC系统的步序逻辑控制,能够很好的完成钢轨的定尺和锯钻,大大提高了产品的加工精度.     

超高强DP980钢的静态软化行为

采用Gleeble-3500热力模拟机对超高强双相钢DP980进行双道次压缩试验,研究其在950~1150 ℃、道次间歇时间1~500 s条件下的静态软化行为,并建立了静态再结晶动力学模型。结果表明：相同变形条件下,软化程度随温度升高而加强;相同温度下,随道次间歇时间的延长,软化率增加。DP980双相钢静态再结晶软化50%所需时间t0.5为：,静态再结晶的激活能=341.6 kJ/mol。静态再结晶动力学模型为：,对比试验与计算结果,模型能很好地预测静态再结晶软化率。     

高效液相色谱法测定竹筷中噻苯咪唑、邻苯基苯酚和联苯

建立高效液相色谱测定竹筷中噻苯咪唑、邻苯基苯酚、联苯的方法。以甲醇为提取溶剂,用索氏提取法提取竹筷中噻苯咪唑、邻苯基苯酚和联苯3种保鲜剂。以甲醇-水(体积比70:30)为流动相,流速1.0mL/min,采用C18柱(250mm×4.6mm,5μm)分离,紫外检测器检测,检测波长247nm,进样量20μL。方法的相关系数均大于0.999,最低检出限为0.01μg/mL,平均回收率为95.8%～97.1%,相对标准偏差为1.4%～2.6%。应用所建立的方法测定一次性竹筷中噻苯咪唑、邻苯基苯酚、联苯的残留量,结果表明：该方法样品处理简单,色谱分离完全,结果准确可靠,适于竹筷中噻苯咪唑、邻苯基苯酚和联苯的分析检测。     

固定式金属热锯PLC故障分析及采取的措施

根据2M热锯PLC系统运行故障分析,查找原因并采取相应措施。     

一种基于SIMATICT—CPU的运动控制伺服系统设计

设计和论证了一种以西门子SIMATICT—CPU315T-2DP作为轴的运动控制器,以IM174作为通信模块连接伺服电机和控制器,控制伺服电机完成各种电机运动,以及多套伺服电机组成的电机群之间的同步运动和组合复杂运动的可行方案。经实践检验,这种方案简单易行,可以作为一般运动控制伺服系统设计的模板。     

Finite element simulation and experimental investigation of thermal tensioning during welding of DP600 steel

The locally introduced heating and cooling cycle of welding generates residual stresses and distortion. Costly post-weld heat treatments are required in order to reduce welding residual stresses and distortion. Thermal tensioning is one of the more promising in-process techniques to control welding distortion and can be classified into transient thermal tensioning (TTT) and side heating (SH). In thermal tensioning additional heat sources are applied during welding. If the additional heaters are close to the weld centre line and influence the thermal field of the weld, the process is called TTT. If there is no interference to the thermal field of the weld, the process is called SH. In this work, the SH during welding of 2?mm thick DP600 steels has been extensively investigated using numerical and experimental approaches. The thermal and mechanical fields during conventional welding and SH were examined by means of finite element models, and validated by comparison with experimental observation of temperature, distortion and residual stresses. The microstructure was investigated experimentally.     

基于协议互补法的嵌入式工业以太网与现场总线协议转换器

首先介绍了MODBUS/TCP工业以太网协议和PROFIBUS-DP现场总线协议.从理论角度探讨了协议转换的实现方法,利用协议互补法原理研制出嵌入式MODBUS/TCP工业以太网与PROFIBUS-DP现场总线协议转换器.