The correlation of the heat flux on the anode surface with the plasma properties at the free-fall edge was developed. By using the models of the tungsten inert gas (TIG) welding arc and the anode boundary layer, the heat transfer contributions to the anode heat flux in TIG welding were analyzed. The percentages of the electron flow contribution and the convection contribution were determined. The results show that the energy carried by the electrons constitutes most of the heat on the anode surface. 2001 Elsevier Science B.V. All rights reserved.

Achieving an effective utilization and exploitation of TIG welding arcs require a thorough understanding of the plasma properties and its physical processes. Through simultaneous solutions of the set of conservation equations for mass, momentum. Energy and current. a mathematical model has been developed to predict the velocity, temperature, and current density distributions in argon welding arcs. The predicted temperature fields in arc regions, and the distribution of current density and heat flux at the anode agree well with measurements reported in literatures. This work could lay the foundation for developing a comprehensive model of the TIG welding process wheve a dynamic, two-way coupling between the welding arc and the weld pool surface is properly represented.

This paper introduces a fuzzy logic system that is able to recognize common disturbances during automatic gas metal arc welding (GMAW) using measured welding voltage and current signals. A statistical method was employed to process the captured transient raw data, and the probability density distributions (PDDs) and the class frequency distributions (CFDs) were obtained. Based on the processed data (PDD values of welding voltage and current and CFD values of the short-circuiting time), the system automatically generates fuzzy rules and membership functions of linguistic variables, conducts inference and defuzzification, and completes the evaluation process without further expert knowledge.

根据当前制造业对高效、优质、低耗焊接技术的迫切要求，研发出低成本的高速电弧焊接新工艺DE-GMAW。该工艺在常规GMAW焊接设备的基础上，通过附加GTAW焊枪构成旁路电弧，分流了一部分通过焊丝的焊接电流，在施加于焊丝的电流较大的情况下（保证了熔敷率），减小了作用于母材的热输入，解决了高速焊接面临的矛盾，实现了高速电弧焊接。建立了适用于DE-GMAW焊接工艺的有限元模型，并对该工艺条件下的温度场和应力变形进行了数值模拟。结果表明：计算出的DE-GMAW焊缝横断面形状尺寸与实验结果吻合良好；在通过焊丝的总电流相同时，DE-GMAW焊接时焊缝尺寸、热影响区宽度、应力、应变及变形均小于常规GMAW焊时的结果。这为DE-GMAW焊接工艺参数优化提供了基础数据。

Establishing the correlation between transient behaviors of surface deformation of weld pools and workpiece penetration information, and quantitatively analyzing the surface deformation at top and bottom surfaces at the moment when the pool is penetrated and their dynamic responses to welding process parameters will provide many basic data for the realization of topside vision-based penetration control in gas tungsten arc welding (GTAW). A transient numerical model is developed to investigate the dynamic behaviors of full-penetrated GTAW weld pools in this paper. A whole and comprehensive scheme is used in which many factors such as moving arc, 3-D fluid and heat flow fields, transient state, full-penetrated weld pool and surface deformation at both top and bottom surfaces are considered. The transient developments of 3-D surface deformation and shape of weld pool during the period from partial penetration to full penetration are predicted. The simulated results show that the curves of ratios of the maximum depression to the length and width at top surface of weld pool at different times clearly indicate the basic information of penetration. So the relation of the ratios versus time can be used as an indicator to judge whether the weld pool is penetrated.