电阻焊焊接电源发展方向之探讨

电阻焊焊接工艺是当今世界上应用最广的焊接方法之一,本文对电阻焊焊接电源今后发展趋势进行了探讨,提出了新世纪电阻焊焊接电源的主要发展方向,即继续开发高效节能三相均衡的电阻焊焊接电源将仍是２１世纪的主题;各种以软开关为特征的逆变式电阻焊机将得到长足的发展;并对电阻焊电源的新技术原理和市场前景进行了详细介绍。     

热冲压高强钢电阻+激光组合点焊工艺

为避免热冲压高强钢电阻点焊在热输入较大时产生飞溅和满足激光点焊装配要求,提出一种将电阻点焊和激光点焊组合的新焊接工艺方法.通过电阻+激光组合点焊工艺获得了热冲压高强钢焊接接头,分析了接头各区域的显微组织、显微硬度分布、力学性能,并分析了断裂模式及其断裂机理.结果表明,电阻+激光组合点焊接头明显分为电阻焊接区和激光焊接区.母材和激光焊核区硬度值较大,与回火区对应的软化区硬度值下降约60％,激光环外侧软化区为拉剪断裂薄弱环节.此种组合工艺获得的焊接接头相对于单独电阻点焊或激光点焊强度和韧性都有明显提高.     

New technology for measuring resistance of electrical contact and estimating welding quality

Incomplete penetration is a common defect in the welding gap of large size (welding area is over 100 mm²) electrical contact, which leads to an instability of welding quality. Nevertheless, there was limited research dealing with non-destructive quality inspection of electrical contact. In this research, the resistance of CJ400 electrical contact was measured with the device medium frequency inverter resistance spot welding (MFI-RSW) machine. Multipulse measuring method was designed and proved efficient to reach a higher accuracy by restraining the influence of the contact resistance between electrodes and electrical contact. Moreover, the error of resistance caused by temperature rising in the measuring process is also eliminated effectively. Therefore, more accurate resistance of electrical contact could be extracted compared to the method of single pulse measuring. Then, the relationship between resistance and welding quality was studied and a new quality inspection method was proposed.     

等效电阻互模糊熵诊断铝合金双丝PMIG焊稳定性

铝合金双丝脉冲惰性气体保护(pulse metal inert gas, PMIG)焊焊接过程中两个电弧之间的相互作用对焊接稳定性的影响非常关键,并且焊接电弧等效电阻相较于焊接电流与弧压包含更全面的电弧信息,基于此提出了等效电阻互模糊熵方法来评价铝合金双丝PIMG焊接过程稳定性. 对3A21铝合金进行了一系列双丝PMIG焊接试验研究,计算其等效电阻互模糊熵,证实焊接过程越稳定等效电阻互模糊熵值越大. 设计了焊接稳定性状态存在突变的焊接试验,将焊接电弧等效电阻模糊熵与互模糊熵对稳定性突变的敏感性进行了对比. 结果表明,等效电阻互模糊熵比模糊熵对焊接过程稳定性的变化更加敏感,能更准确地诊断出焊接过程稳定性的突变点.     

Physico-mathematical model of resistance projection welding of cruciform joints

Resistance projection welding is used widely in the manufacture of various structures. To determine welding conditions resulting in the required quality of welded joints, experiments must be carried out using methods of computer analysis based on a physico-mathematical simulation. The model of the welding method is based on a system of equations of the electric potential, thermal conductivity and plastic deformation, and also the relationships linking the properties of metal with its thermodynamic state. A special feature of the model is the need to describe the geometry of the welded joint. This approach is based on an example of the process of projection welding of cruciform joints in bars. The results show that the proposed simulation methods can be used for analysis of the process of projection welding of different joints.     

Research on micro-electric resistance slip welding of copper electrode during the fabrication of 3D metal micro-mold

3D micro-mold fabricated by the micro double-staged laminated object manufacturing process (micro-DLOM) is formed via stacking and fitting of multi-layer 2D micro-structures. The connection of 2D micro-structures is related to forming accuracy and mechanical properties of 3D micro-mold. In this research, micro-electric resistance slip welding of copper electrodes was proposed to connect multi-layer 2D micro-structures. Firstly, the proper process parameters of slip welding were obtained through the welding experiment, and the temperature field of micro-electric resistance slip welding under such process parameters was simulated. Secondly, deposition effect of the copper bar electrode produced during slip welding was studied and the study results show that the copper element deposited in the slip welding area decreases as the surface roughness of copper electrode decreases. Finally, based on the above research, a square micro-cavity mold with micro-channel, a circular micro-cavity mold with cross keyway and micro gear cavity mold with two-stage steps were welded by the micro-electric resistance slip welding.     

超声-电阻复合焊接方法及界面行为

有色金属微型零件超声焊接时,由于焊头面积小,输入焊接区域能量少,界面有效连接面积不足,影响焊接接头的力学性能. 针对这一问题,结合超声焊接与电阻焊的特点,研制了超声-电阻复合焊接系统. 对铜、铝异种金属进行了超声-电阻复合焊接工艺试验,并与相同工艺条件下的超声焊接进行了对比. 结果表明,电流对超声能的输出有促进作用,使换能器的峰值功率有明显的增加;超声使焊接起始阶段界面接触电阻迅速减小并消失;在复合能量的作用下,输入焊接区域总能量有较大提高,焊接区域温度和加热速率显著增加.     

通过监测电极位移的模糊控制铝合金点焊

利用热弹塑性有限元来仿真研究铝合金的点焊过程,分析了焊接电流和电极挤压力对点焊质量的影响。研究了电极位移与焊接电流和挤压力间关系,证明电极位移表征了点焊质量,只要电极位移控制在一个合适的范围内,就能得到理想的点焊质量。在此基础上,提出监控电极位移,利用模糊控制方法,实时改变点焊的电流,从而控制点焊熔核尺寸,达到良好的点焊质量。由于模糊控制的引入,极大地扩大了点焊对挤压力等的适应能力,方便了点焊初始参数的选取。     

Weldability of low-alloy steels in submersion-arc welding at high linear energies

Results of analysis of investigations of welded joints produced in welding low-alloy high-strength 07G2NDMFBT steel at linear energies up to 6 kJ/mm show that the proposed combinations of welding materials and the technology of multi-arc submerged-arc welding result in high hot-cracking resistance and high properties of the weld metal. However, regardless of the high cold-cracking resistance of the steel, in welding at high heat inputs there is a considerable degradation of the structure and the toughness of the metal in the coarse-grained region of the heat-affected zone decreases under the effect of the welding thermal cycle. Consequently, it is concluded that the weldability of this steel is limited and it is therefore necessary to apply restrictions in the practical application of the processes with high heat input.     

电阻点焊电流和压力信号的在线测量

阐述基于霍尔效应测量电阻点焊大电流的原理,设计采用霍尔器件的二次电流传感器;采用电阻应变式传感器测量电极压力,该装置安装于气缸内;用线性回归法标定传感器;实验结果表明,提出的电流测量方法和内置式的应变式压力传感器可以提高电阻点焊焊接电流和电极压力的测量精度.     

铝合金点焊的多场耦合建模与动态过程数值模拟(英文)

基于铝合金点焊的热、机、电及相变原理,建立热电力耦合场的轴对称有限元数值仿真模型,实现对焊接区温度场、电场、应力应变的动态模拟。发现了焊接电流变化激发的铝合金动态电阻"瞬态逆向虚变效应",揭示了过程热电耦合瞬态与稳态差异性作用机理,阐释了焊接电流增加而瞬态电阻骤降的反常现象。基于铝合金点焊稳态仿真与实验结果修正了动态电阻数值计算模型。AA5182的计算与实验结果表明,考虑动态电阻"瞬态逆向虚变效应"的动态仿真模型能够精确描述焊接电流调整过程中的电参数动态变化和铝合金焊点熔核的生长过程。     

IR761／125型点焊机器人在平头驾驶室总装生产线上的应用

介绍了ＩＲ７６１／１２５型点焊机器人的机械结构和控制系统；重点讨论了机器人的焊接应用；提出了机器人的使用维护和故障处理建议。     

铝钢点焊铆接复合连接技术

提出了一种点焊与铆接复合进行铝钢连接的技术,即在待焊试样区域预制工艺孔,将铆钉铆入孔中,利用铆接力实现试样的预连接.然后使用点焊机在铆接位置进行点焊,实现铆接与点焊的复合连接,称为"点铆焊".文中分析了该方法的力学性能、微观组织、断裂模式,并同纯点焊与纯铆接进行了比较.结果表明,点铆焊的抗拉强度比纯点焊提高了23.8%,比纯铆接提高了28.7%,失效前吸收功比纯点焊提高211%,比纯铆接提高67%.虽然在点铆焊过程中也会产生脆性金属间化合物,但这些区域并不是主要的承载部位,点铆焊为塑性断裂模式.     

AZ31B镁合金/镀锌钢板电阻点焊接头形成机理

针对2.0 mm厚的AZ31B镁合金以及1.0 mm厚的SPHC镀锌钢板,采用KDWJ-17型三相次级整流电阻焊机进行焊接试验,通过光学金相、扫描电镜等方法分析接头各区域的组织结构和成分分布.提出了镁锌低熔点化合物挤压机制,分析了Zn元素在镁合金和镀锌钢板电阻点焊中的作用.结果表明,Zn与Mg元素形成的低熔点化合物MgZn₂在电极压力的作用下能填满由于焊接变形引起的间隙,使反应界面密封,促进Fe,Al元素在界面发生处扩散,Fe与Al元素在界面处发生反应生成Fe₂Al₅化合物,从而形成高强度的镁合金与镀锌钢板的电阻点焊接头.     

催化转换器最优封装工艺研究

通过热-力单向耦合,将温度场结果施加到应力场上,依据焊接热弹塑性有限元分析理论,考虑到材料随温度变化的力学性能以及材料的应变强化,对三种封装工艺的催化转换器进行应力和变形的数值模拟。最后,从残余应力、变形、封装时间和焊缝抗热裂性等方面对比三种封装工艺的催化转换器,从实际生产效率和产品质量的角度,得出较好的封装焊接工艺。     

短路过渡焊接焊丝干伸长传感器

对波形控制短路过渡CO2 焊接焊丝干伸长传感器进行了研究。在对焊丝干伸长传热和电阻以及熔滴的几何形状和电阻特性进行理论分析的基础上 ,建立了一套基于MotorolaMC6 8HC11A1单片机的焊丝干伸长检测及处理系统。短路期间的焊丝干伸长近似为焊炬至工件的距离 ,因此焊丝干伸长可作为确定焊炬高度的传感器 ,进而实现焊缝跟踪。对检测数据的处理结果表明 ,在短路中期 ,焊接脉冲电流恒定 ,焊炬与工件间的电压信号与焊丝的干伸长度成正比。传感器的实际检测精度可以达到± 0 .4mm ,完全能够满足CO2 焊接的焊炬高度跟踪和焊丝能量补偿控制的要求。     

电阻点焊应变式压力传感器弹性体的设计及应用

针对电阻点焊压力的在线监测,根据电阻点焊电极受力分析结果,提出通过缩短压力传感器与电极间的安装距离、减少受力不平衡带来的测量误差的方法。设计可直接安装在下电极及其电极握杆之间的应变式压力传感器,并对其弹性体进行设计计算。测试结果表明,该传感器能够实时测量电阻点焊过程中的电极压力,及时响应点焊熔核形成过程压力的瞬时变化,可间接预测熔核大小、监测焊接过程中的飞溅。     

新型工业材料的点焊工艺研究现状

概述了镀锌钢和铝合金这两种新工业材料的点焊工艺特点以及国内外在这方面的研究现状，详细分析了这两种材料在电阻点焊中存在的严重问题－电极的磨损和沾污。     

汽轮机阀座堆焊开裂原因分析与对策

汽轮机阀座由于长期承受苛刻的工作环境,接触密封面常采用堆焊硬质合金司太立6的方式以增强阀座密封面耐磨性和密封效果.本文就典型的20Cr1 Mo1V材料阀座司太立合金堆焊面开裂原因进行分析,提出了司太立合金堆焊质量的控制措施.     

图像处理在电阻点焊质量检测中的应用

现代制造业广泛使用电阻点焊技术,研究者长期致力于实现焊接质量快速无损检测技术的研究,本文以低碳钢为试验材料,在各种点焊工况下对焊点图像进行了采集与预处理,利用分形理论对焊点图像边缘进行检测,结果证明,利用分形几何可有效提取焊点边缘.文中研完了焊点图像特征区域面积与焊点强度之间的关系,结果表明,焊点表面图像面积与焊点强度之间呈正比例关系,可以利用焊点表面图像对点焊质量进行检测.