Arc welding

About: Arc welding is a research topic. Over the lifetime, 25393 publications have been published within this topic receiving 168182 citations.

Pulse arc welding device

Abstract: PURPOSE: To reduce arc voltage, prevent arc breaking and stabilize the arc by increasing background current when an arc voltage detected value rises above a set value. CONSTITUTION: A pulse current waveform is supplied to the arc 6 by a pulse current source 21 and a background current source 22. At this time, the arc voltage is detected with an arc voltage detector 23 and is compared with the reference voltage of an arc voltage reference setter 24 in a comparator 25. When the arc voltage is larger than the reference voltage, a current increase command is given from the comparator 25 to the source 22 which in turn flows the current added with the current value having beforehand been corrected with a background current corrector 26 to the arc 6. Hence, when it comes to the point of the time I when the arc is liable to break in the background part, the arc voltage rises and at the same time the background current value 2 begins to lower. At the point of the time II when the arc voltage exceeds the reference voltage, the background current 2 is increased, thereby stabilizing the arc. Then, the arc voltage decreases and at the same instant the command of the comparator 25 stops. At the point of the time III, the background current resumes the original value. COPYRIGHT: (C)1982,JPO&Japio

An adaptive feature extraction algorithm for multiple typical seam tracking based on vision sensor in robotic arc welding

Abstract: Intelligent robotic welding is an indispensable part of modern welding manufacturing, and vision-based seam tracking is one of the key technologies to realize intelligent welding. However, the adaptability and robustness of most image processing algorithms are deficient during welding practice. To address this problem, an adaptive feature extraction algorithm based on laser vision sensor is proposed. According to laser stripe images, typical welding seams are classified into continuous and discontinuous welding seams. A Faster R-CNN model is trained to identify welding seam type and locate laser stripe ROI automatically. Before welding, initial welding point is determined through point cloud processing to realize welding guidance. During seam tracking process, the seam edges are achieved by a two-step extraction algorithm, and the laser stripe is detected by Steger algorithm. Based on the characteristics of two kinds of welding seams, the corresponding seam center extraction algorithms are designed. And a prior model is proposed to ensure the stability of the algorithms. Test results prove that the algorithm has good adaptability for multiple typical welding seams and can maintain satisfying robustness and precision even under complex working conditions.

Heat Transfer and Fluid Flow during Gas-Metal-Arc Fillet Welding for Various Joint Configurations and Welding Positions

Abstract: Gas-metal-arc (GMA) fillet welding is one of the most commonly used welding processes in the industry. This welding process is characterized by the complex joint geometry, a deformable weld pool surface, and the addition of hot metal droplets. In this work, a three-dimensional numerical heat-transfer and fluid-flow model is developed to capture the effects of the tilt angle of the fillet joint and the welding positions, i.e., V, L, and other configurations on the temperature profiles, velocity fields, weld pool shape, weld pool free surface profile, thermal cycles, and cooling rates during GMA welding in spray mode. The governing equations of conservation of mass, momentum, and energy are solved using a boundary fitted curvilinear coordinate system. The weld pool free surface deformation is calculated by minimizing the total surface energy. A dimensional analysis is performed to understand the importance of heat transfer by conduction and convection and the role of various driving forces on convection in the liquid weld pool. The computed shape and size of the fusion zone, finger penetration characteristic of the GMA welds, and the solidified free surface profile are in fair agreement with the corresponding experimental results. The calculated cooling rates are also in good agreement with independent experimental data. The results reported here indicate a significant promise for understanding the effect of joint orientations and welding positions on weld pool shape, size, and the cooling rates based on fundamental principles of transport phenomena.

Metal transfer in arc welding as a varicose instability. II. Development of model for arc welding

Abstract: For pt.I see ibid., vol.18, p.1431 (1985). A model of metal transfer in open arc welding is developed which provides a framework for predicting the influence of welding parameters in steady and pulsed current welding. It is found possible to present results in terms of simple expressions which are in broad agreement with available observations. Considered here are aspects such as droplet evolution, detachment frequency and size, selection of pulse parameters, influence of electrostatic stress on transfer, drop dynamics and the relationship between balance of force approaches to transfer and the present instability model.