数控变极性等离子弧焊中心的研究设计

本文结合焊接技术的特点和社会经济发展的要求,研究设计的数控变极性等离子弧焊中心采用了DSP控制技术,通过编程,实现焊接过程的数字化控制,配以焊缝的自动跟踪,达到各轴各参数相互间的有机联动,实现整个系统的自动化,完成不同形状大小焊缝的成形控制.     

Heat input in full penetration welds in gas metal arc welding (GMAW)

Weld bead characteristics are metallurgically controlled by heat input, which depends on the welding parameters. However, for numerous welding specialists, an accurate measurement of the current, voltage, and welding speed is enough for preventing unambiguous process specifications. But a comprehensive knowledge of the effect of others parameters, such as plate thickness and the type of pass to be performed (full penetration, root pass, or filler pass), is also required if a less conservative welding procedure is aimed. The goal of the present paper is to increase the ability to control the quality of the welding processes used in production by considering the effect of heat losses through the back side of the weld by radiation for full penetration welding, when developing welding procedure specifications. It is concluded that the thermal efficiency factor and, consequently, the heat input need to be differentiated in the welding specifications for full penetration welding.     

3A21铝合金激光焊与激光-氩弧焊复合焊微观组织及性能比较研究

采用激光焊接与激光-氩弧焊复合焊接2种方式对厚度为2mm的3A21铝合金板材进行对接焊,研究2种焊接方式下焊接接头微观组织、缺陷分布及硬度分布的不同。实验结果显示激光-氩弧复合焊接接头相比激光焊的接头显微组织更细密,且气孔数量明显减少。激光焊接接头的平均显微硬度与复合焊接头平均显微硬度相差不大,分别为52HV左右及51.3HV左右,均明显高于基体平均显微硬度值43HV。     

IGBT逆变弧焊电源CO2气体保护焊飞溅的波形控制

随着逆变焊机的发展和数字技术的应用,逆变CO2气体保护焊电源可通过调节焊接电源输出的电流与电压来控制熔滴过渡,改善焊缝成形,降低飞溅.根据熔滴过渡不同阶段的要求产生电流与电压控制信号,进行波形控制可实现调节短路电流上升速度,以减小短路峰值电流,降低短路爆炸能量;减少瞬时短路的次数;通过短路后期液桥颈缩电压上升率切断短路电流,消除电爆炸能量.以此有效减少CO2气体保护焊短路过渡产生的飞溅量,为低飞溅CO2气体保护焊的设计与实现提供有力保证.     

Modeling of heat transfer and fluid flow during gas tungsten arc welding of commercial pure aluminum

In the present study, the temperature and the velocity fields during gas tungsten arc welding of commercial pure aluminum were simulated using the solution of the equations of conversation of mass, energy and momentum in three dimensions and under steady-state heat transfer and fluid flow conditions. Then, by means of the prediction of temperature and velocity distributions, the weld pool geometry, weld thermal cycles and various solidification parameters were calculated. To verify the modeling results, welding experiments were conducted on two samples with different thicknesses and the geometry of the weld pool was measured. It is found that there is a good agreement between the predicted and the measured results. In addition, dimensional analysis was employed to understand the importance of heat transfer by convection and the roles of various driving forces in the weld pool. It is observed that the molten metal convection strongly affects on the weld pool geometry. Also the predictions make it possible to estimate the morphology and the scale of the solidified structure through solidification parameter (G/R). The result show that as the net heat input increases, the importance of convection becomes higher and the value of G/R at the weld pool centerline increases.     

Experimental study and numerical modeling of arc and weld pool in stationary GTA welding of pure aluminum

In this study, a 2D mathematical model was developed for both arc and weld pool in stationary GTA welding. In arc model, current continuity equation has been solved in both arc and cathode regions without any assumption of fixed current density on the cathode surface which was essential in most previous works. The results of arc model were presented for both copper and aluminum anodes to investigate the effect of anode material on arc properties. It was seen that aluminum anode has lower maximum anode current density and heat flux but the distributions are wider than copper anode. Furthermore, shear stress on anode surface is higher in the case of aluminum anode. Also, calculated results of this study were compared with other available theoretical and experimental results. It has been shown that the agreement between calculated and experimental results was fairly good. The necessary information to simulate the weld pool, including the anode current density and heat flux to the workpiece were taken from the arc model. In this model, due to high thermal conductivity of pure aluminum, fluid flow into the weld pool was ignored. Effects of arc variables, i.e., arc length, applied current and welding time on the shape and size of the weld pool were investigated as well. In order to check the validity of the weld pool model, a comparison between calculated results and the results of our experimental tests was conducted. Generally, these comparisons reveal an acceptable agreement between calculated results and experimental data.     

弧焊电源的智能控制

简要介绍在弧焊电源中成熟应用的智能控制技术及方法。     

手工电弧焊电弧电压控制的研究

采用手工电弧焊进行焊接时，电弧电压是一个很难控制的工艺参数。有时对焊接质量产生较大影响。本文针对职业技术类院校焊接专业学生在进行手弧焊实训时难以控制弧长（电弧电压）的问题提出一种解决方案——设置超压报警系统。当弧压增大到超过预设值时，系统报警提醒操作者调节弧长，从而将电弧电压控制在预设值之下。     

Predicting the combined effect of TiO2 nano-particles and welding input parameters on the hardness of melted zone in submerged arc welding by fuzzy logic

Submerged arc welding (SAW) is a high-quality arc welding process used in heavy industries for welding thick plates. In this process, selecting appropriate values for the input parameters is required for high productivity and cost effectiveness. A very important weld quality characteristic affected by welding input parameters is the hardness of melted zone (HMZ). This paper reports the applicability of fuzzy logic (FL) to predict HMZ in the SAW process which is affected by the combined effect of TiO₂ nano-particles and welding input parameters. The arc voltage, welding current, welding speed, contact tip-to-plate distance, and TiO₂ nano-particles were used as input parameters and HMZ as the response to develop FL model. A five-level five-factor central composite rotatable design (CCRD) was used in the experiments to generate experimental data. Experiments were performed, and HMZs were measured. The predicted results from FL were compared with the experimental data. The correlation factor value obtained was 99.99% between the measured and predicted values of HMZ. The results showed that FL is an accurate and reliable technique for predicting HMZ because of its low error rate.     

Advanced gas metal arc welding processes

There is an increased requirement in the automotive, food and medical equipment industries to weld heat-sensitive materials, such as thin sheets, coated thin plates, stainless steel, aluminium and mixed joints. Nevertheless, relevant innovations in arc welding are not widely known and seldom used to their maximum potential. In the area of gas metal arc welding welding processes, digitalisation has allowed integration of software into the power source, wire feeder and gas regulation. This paper reviews developments in the arc welding process, particularly the effect of the set-up of the welding process parameters on waveform deposition. It is found that good weldability, good mechanical joint properties and acceptable process efficiency can be obtained for thin sheets through advanced power source regulation, especially over short circuiting, controlled polarity and electrode wire motion. The findings presented in this paper are valuable for waveform and deposition prediction. The need is furthermore noted for an algorithm that integrates gas flow parameters and wire motion control, as well as a variable sensor on the tip of the electrode, permitting flexibility of control of the current and the voltage waveform.     

离线编程式弧焊机器人研制

详细介绍了离线编程式弧焊机器人的系统组成、工作原理、计算机控制系统、操作界面.通过焊接实验证明该机器人工作稳定,焊缝形状完全符合要求.     

石油钻机井架弧焊机器人位姿误差分析

介绍了石油钻机井架焊接机器人本体结构和机器人位姿误差分析的"小位移摄动法",利用该方法建立了弧焊机器人的位姿误差分析模型.计算结果证实了位姿误差分析的正确性,为机器人的位姿误差补偿及精度优化设计提供了依据.     

Physical characteristics of welding arc ignition process

The existing research of welding arc mainly focuses on the stable combustion state and the research on the mechanism of welding arc ignition process is quite lack.The tungsten inert gas(TIG) touch arc ignition process is observed via a high speed camera and the high time resolution spectral diagnosis system.The changing phenomenon of main ionized element provided the electrons in the arc ignition is found.The metallic element is the main contributor to provide the electrons at the beginning of the discharging,and then the excitated shielding gas element replaces the function of the metallic element.The electron density during the period of the arc ignition is calculated by the Stark-broadened lines of Hα.Through the discussion with the repeatability in relaxation phenomenon,the statistical regularity in the arc ignition process is analyzed.The similar rules as above are observed through the comparison with the laser-assisted arc ignition experiments and the metal inert gas(MIG) arc ignition experiments.This research is helpful to further understanding on the generation mechanism of welding arc ignition and also has a certain academic and practical significance on enriching the welding physical theoretical foundation and improving the precise monitoring on automatic arc welding process.     

3-dimensional numerical analysis of friction stir welding of copper and aluminum

Journal of Mechanical Science and Technology - A time dependent Eulerian thermal/material flow model of friction stir welding was developed and applied to the dissimilar joining of pure copper and...     

手工电弧焊接起重机运行轨道

桥、门式起重机大车运行轨道应尽量使用无缝钢轨 ,但由于诸多因素的限制 ,大多数只能使用标准长度为 12 5ｍ的旧轨 ,这样每 2 0 0ｍ线路上就分别有 16个接头 ,因此给起重机运行带来冲击、振动 ,不仅造成钢轨出现低接头 ,而且对起重机各部件的使用寿命与维修周期、司机的舒适、货物的平稳安全等都有影响。为此通过焊接方法实现无缝长轨具有重要的现实意义。目前 ,铝热焊接钢轨技术应用最为广泛 ,但成本较大 ,请工务段焊一个接头需 2千元 ,且操作复杂 ,不易推广使用。我站应用最普通的交流手工电弧焊机对既有线路的钢轨进行焊接 ,焊一个接头…     

双工位弧焊机器人系统控制方法

本文介绍了一种基于焊接机器人组成的不锈钢充气柜的焊接工作站、电气组成特点和各个组成单元的协调控制方式.     

Weld formation control for arc welding robot

The control of weld formation in gas tungsten arc welding is required for “teach and playback” robot to suit the gap variation in the multi-pass welding process. This paper presents a robotic system based on the real-time vision measurement. A close-loop control system is developed for weld formation control in backing welding. A novel prediction model of reinforcement is investigated as the feedback element. At last, the feasibility of proposed system was validated in the experiments.     

Melting rate of electrode wire in arc welding

A mathematical model is proposed for the melting rate of electrode wire during the arc welding of low-alloy steel in protective gases. The discrepancy with experimental data is no more than 4%.