Numerical analysis of arc-droplet behavior in thin wire high current MAG welding with magnetic control

High efficiency welding has always been one of the hot research subjects at home and overseas. Aiming at the problem of unstable droplet rotating spray transfer process in 450 A thin wire metal active gas arc(MAG) welding, a three-dimensional arc-droplet coupled model is established in this paper on the base of fluid dynamics to conduct numerical analysis for droplet transfer behavior with external magnetic controlled MAG welding, and used high-speed camera system to verify the simulation result...     

Parameter optimization of dissimilar resistance spot welding on ultra-high strength hot-stamped steel and mild steel by numerical simulation

In this study,a coupled axisymmetric finite element model (FEM) was built to simulate the resistance spot welding (RSW) process between ultra-high strength hotstamped (UHSS) and mild steel by SORPAS software.Via simulating this process,the temperature distribution and dynamic temperature curves of the welding area were studied,and welding spatter phenomena were predicted and validated by comparing them with experimental results.By adjusting the welding parameters in numerical simulation,appropriate welding parameters were achieved.Moreover,the mechanical properties of the welding joints under the optimized conditions were also compared with those of not optimized.The study results have already been applied in a manufacturing production.It can also provide guidance for the RSW on UHSS and mild steel.     

Research of novel oscillating wire feeding system using the AC servo motor

With the background of the control of additional mechanical force droplet transfer in MIG/MAG welding, regarding the AC servo motor as core, a novel oscillating wire feeding system has been developed with excellent performances of control and dynamic acceleration which is tested. System constitution and operation principle are introduced in this paper. Influences of parameters on dynamic acceleration performance are analyzed and discussed emphatically, such as oscillating frequency, oscillating amplitude and draw-back speed. Experimental result indicates that according to the technique of welding control, the novel wire feeding system responds rapidly to various kinds of control orders of wire feeding and draw-back, and realizes flexible control of welding wire axial movement, including dynamic shifting ,oscillating and so on.     

Computer simulation of short-circuiting transfer welding under waveform control on inverter power source

A simulation model is introduced about the non-linearity process of short-circuiting transfer in CO2 arc welding for displaying the interaction between the inverter power source and welding arc under waveform control. In the simulation model, the feedback signals of current and voltage are taken respectively at the different phase in a short circuit periodic time and applied to the PWM （pulse width modulation） module in a model of inverter power source to control the output of power source. The simulation operation about the dynamic process of CO2 short-circuiting transfer welding is implemented on the founded simulation model with a peak arc current of 400 A and a peak voltage of 35 V, producing the dynamic arc waveforms which can embody the effect of inverter harmonic wave. The simulating waveforms are close to that of welding experiments.     

Vision-based detection of MAG weld pool

Weld pool contains significant information about the welding process. The weld pool images of MAG welding are detected by LaserStrobe system. An algorithm for extracting weld pool edge is proposed according to the characteristics of MAG weld pool images. The maximum weld pool length and width are calculated. The measurement data can be used to verify the results of welding process simulation and to provide a good foundation for automatic control of MAG welding process.     

Mathematical modeling and simulation application for a wheeled mobile robot applied on pipe welding

A geometric model was built to represent the position relation of a wheeled mobile robot relative to a pipe. The relationship between the deviation of falling off for the robot and the curvature of the pipe was formulated quantitatively. Based on the relationship, a mathematical model was derived and a fuzzy control algorithm for the robot was developed. Simulations were carried out to confirm the dynamic index and the validity of the mathematical model of the fuzzy control algorithm for seam tracking of pipe welding. Experiments for pipe welding with the mobile robot were also carried out to verify the algorithm, and the results showed that the seam has a good quality with a preferable appearance of weld.     

Neuron self-learning PSD control for backside width of weld pool in pulsed GTAW with wire filler

In this paper, the weld pool shape control by intelligent strategy was studied. A neuron self-learning PSD controller for backside width of weld pool in pulsed GTAW with wire filler was designed. The PSD control arithmetic was analyzed, simulating experiment by MATLAB software was done, and the validating experiments on varied heat sink workpiece and varied gap workpiece were successfully implemented. The study results show that the neuron self-learning PSD control method can attain a perfect control effect under different set values and conditions, and is suitable for the welding process with the varied structure and coefficients of control model.     

Temperature field simulation of laser-TIG hybrid welding

The three-dimensional transient temperature distribution of laser-TlG hybrid welding was analyzed and simulated numerically. Calculations were based on a finite element model, in which the physical process of hybrid welding was studied and the coupling effect of the laser and arc in the hybrid process was fully considered. The temperature fields and weld crosssections of the typical welding parameters are obtained using present model. The calculation results shou that the model can indicate the relationship of energy match between laser and arc to joints cross-sections objectively, and the simulation results are well agreed with the experimental results.     

Study on fuzzy control IGBT inverter arc welding power source for robot

Arc welding robot is playing more and more important roles in modern welding manufacturing, but now available welding power sources seldom satisfy with robot system requirements. In this paper, study on fuzzy control IGBT inverter arc welding power source for robot is developed to bring robotic advantages into full play. Firstly, fast response 500A IGBT inverter arc welding rectifier is developed. Secondly, fuzzy control system, which features multi-functions, fast response and wide using range, is developed and reliable measures for preventing interference are designed. Finally, technological experiments for carbon steel are made. The welding experimental results show that the goal of design is attained.     

Phase-field simulation of dendritic solidification using a l＇ull threaded tree with adaptive meshing

Simulation of the microstructure evolution during solidification is greatly beneficial to the control of solidification microstructures. A phase-field method based on the full threaded tree （FTT） for the simulation of casting solidification microstructure was proposed in this paper, and the structure of the full threaded tree and the mesh refinement method was discussed. During dendritic growth in solidification, the mesh for simulation is adaptively refined at the liquid-solid interface, and coarsened in other areas. The numerical results of a three- dimension dendrite growth indicate that the phase-field method based on FTT is suitable for microstructure simulation. Most importantly, the FTT method can increase the spatial and temporal resolutions beyond the limits imposed by the available hardware compared with the conventional uniform mesh. At the simulation time of 0.03 s in this study, the computer memory used for computation is no more than 10 MB with the FTT method, while it is about 50 MB with the uniform mesh method. In addition, the proposed FTT method is more efficient in computation time when compared with the uniform mesh method. It would take about 20 h for the uniform mesh method, while only 2 h for the FTT method for computation when the solidification time is 0.17 s in this study.     

基于Matlab/Simulink的全数字控制双脉冲焊建模和仿真研究

应用Matlab/Simulink工具对数字控制逆变焊机进行了整体仿真研究,建立了同时带有功率逆变器、数字控制系统和动态电弧负载的系统仿真模型。从整体上对数字控制逆变焊机系统进行了仿真研究,提出用受控源的方法实现了动态电孤负载模型与系统的连接。仿真结果和实验波形吻合,证明了所建的系统仿真模型的正确性,该仿真研究可以应用于弧焊数字控制器的实现和系统的动态分析。双脉冲焊焊铝具有鱼鳞状焊缝表面美观、有效抑制气孔发生和降低裂纹敏感性等优点。基于所建系统仿真模型,在此对全数字控制的双脉冲焊进行了仿真研究。     

全数字控制CO2焊Matlab/Simulink建模与仿真

利用Matlab／Simulink对全数字控制CO2焊的短路过渡过程进行了仿真，建立了“功率变换电路单元一数字控制单元一送丝单元一短路过渡负载单元”的CO2焊系统仿真模型，从整体上对CO2焊全数字控制逆变焊机系统进行了研究。短路过渡负载模型中考虑了燃弧期间和短路期间熔滴的动态变化过程，采用电弧弧长和电爆炸理论来确定短路燃弧与否，从而使数字控制的效果直接在熔滴行为和电弧行为上得以体现。仿真波形与试验结果基本一致，证明所建的系统仿真模型是正确的。     

基于DSP的单脉冲焊及双脉冲焊全数字控制系统的研究

设计并实现了脉冲焊电流和弧长的全数字控制，取得了良好的控制性能：电流波形的灵活精确控制和弧长的高速稳定调节。采用变参数数字PI调节器，取得了良好的脉冲电流波控效果，同时在孤长调节中不再应用PI或PID控制器，实现了在全范围内对孤长的快速、稳定调节，满足自动焊、无人干涉焊接的需要。实验结果表明，设计的脉冲焊全数字控制系统取得了一致性好的理想电流波形，在焊矩高度等扰动发生时。孤长可以实现快速、稳定地调节。同时将上述设计应用于双脉冲焊焊铝的设计中，实验证明同样获得了好的控制效果和工艺效果。     

全数字化多功能焊接电源平台

建立了包括焊条电弧焊、氩弧、短路过渡、单脉冲和双脉冲在内的五种工艺的焊接电源平台,该平台由焊接电源本体、送丝电机及冷却水箱构成.分析了它的工作原理并阐述了主要功能.重点讨论了短路过渡、单脉冲和双脉冲MIG/MAG焊的工艺全数字实现原理及过程,进行了额定400A的焊接电源平台试验.结果表明,采用全数字控制方法实现多种气体保护焊焊接工艺是完全可行的,在不改变硬件电路情况下,仅仅改变软件就可以满足不同焊接工艺需求,且焊接性能优良.     

全数字控制I/I模式三闭环脉冲MIG焊

提出了一种基于DSP控制的全数字脉冲MIG/MAG控制方法,即自适应电压补偿控制技术的I/I法,该方法可以保证熔滴为一脉一滴过渡.根据送丝速度优先,建立不同材料和丝径的焊接数据库,每个脉冲周期都检测弧长的变化并及时调整熔化能量,同时采用干伸长实时补偿技术以维持弧长恒定.分析了该方法调节原理并建立三闭环系统控制框图.样机试验结果表明,所提出的方法是可行的,具有通用性,在干伸长变化时能够实现等弧长控制,焊接过程稳定,焊缝成形美观.     

大型双丝PMIG焊机器人焊接装备开发及工程化应用的研究

重点阐述大型高效双丝PMIG焊机器人焊接装备技术的研发过程,包括数字化双丝PMIG焊系统、高速焊激光跟踪装置、弧焊机器人+龙门架+变位机的11轴焊接装备的构成及设计技术;介绍了装备在风塔机架大型中厚板构件焊接中的工程化应用案例。     

热沉对焊接残余变形的影响及参数优化分析

对常规的熔化极保护气体焊（MAG）和动态控制低应力无变形（dynamicallycontrolled low stress no-distortion,DC-LSND）MAG焊进行了数值仿真,并对实际的DC-LSND焊件进行了测量,数值仿真结果与试验结果吻合良好.以构架侧梁的焊接残余变形为研究对象,利用数值仿真模型并结合优化算法对热沉参数进行了优化分析,得到了相应的最优方案.结果表明,最优参数下DC-LSND MAG焊控制焊接残余变形的效果明显.     

PMIG焊焊接电弧电压的模糊控制

模糊控制是一种新型智能控制方法。本文介绍作者拟对脉冲熔化极气体保护焊(PMIG焊)焊接过程中的电弧电压参数进行模糊控制,取得了良好的焊接电弧稳定性和焊缝成形的效果。