Papers by Keyword: Resistance Spot Welding (RSW)

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Authors: Zhi Gang Hou, Jun Zhao, Li Qiang Xu, Zhong Guo
Abstract: In order to theoretically simulate the welding process of complex structure with large quantities of welding spots, a simplified method for analyzing a single spot welding should be developed firstly. In this paper, a 2D axisymmetric model of thermoelectric Finite Element Method (FEM) is developed to analyze the transient thermal behavior of Resistance Spot Welding (RSW) process using ANSYS. The determination of the contact resistance at the faying surface is moderately simplified to reduce the calculating time, while the temperature dependent material properties, phase change and convectional boundary conditions are taken into account for the improvement of the calculated accuracy. The thermal history of the whole process and temperature distributions for any position in the weldment is obtained through the analysis. The model can also predict the weld nugget size and the width of the Heat Affected Zone (HAZ).
Authors: Zheng Hua Guo, Ping Fang, Jun Hua Cui, Jie Wang
Abstract: A fuzzy neural network based system was developed to control the quality of resistance spot welding. A fuzzy neural controller (FNC) was designed to realize the memory of the fuzzy neural control bases on a back propagation (BP) network, accordingly achieve the mapping of fuzzy input and output. The experiment results show that this method can compensate the multi-crossfire’s influence on the welding currency, keep a high control precision, and fulfill the demand of high precision quality monitoring to the resistance spot welding.
Authors: Taehyung Kim, Yong Suk Lee, Jonggu Lee, Se Hun Rhee
Authors: Li Han, Ken W. Young, R. Hewitt, N. Blundel, Martin Thornton
Abstract: The increased application of lightweight materials, such as aluminium has triggered many investigations into new joining techniques for aluminium alloys. The Resistance Spot Welding concept for aluminium has always attracted many researchers from different organizations. Self-piercing riveting is the major production process used to join aluminium sheet body structures for the automotive industry. Mean while, interest in laser welding and application as a candidate for joining aluminium is also growing. These key technologies for aluminium assembly are therefore being investigated by the research team at the University Of Warwick. The paper reported here looks at the feasibility of each process for joining thin gauge aluminium and compares the mechanical behavior for each joint type. The results suggested that all three joining technologies are feasible for joining aluminum and their mechanical behaviour is strongly dependent on the selection of process parameters
Authors: Yong Joon Cho, In Sung Chang, Heui Bom Lee
Abstract: While resistance spot welding (RSW) has been the most successful sheet metal joining process in automotive industry, there are still certain quality and reliability issues due to the control system and its application process. Some weld spots have hard-to-reach areas and new materials make the process more complicated resulting in new challenges for quality welds. Recently, a new welding machine called one-sided RSW was introduced to make a weld of hard-to-reach areas in automotive application. Intelligent current regulation algorithm of welding machine timer helps to control welding current and time with more stablility than conventional constant current regulation. Newly developed RSW simulation tool is another advanced technology to improve weld quality and production stability. In this research, advanced RSW technologies, including one-sided RSW, intelligent adaptive control, and simulation of RSW process, are discussed with various automotive applications.
Authors: Abderrazak El Ouafi, Rudy Bélanger, Jean-François Méthot
Abstract: The aim of this study is to develop an effective on-line ANN-based approach for quality estimation in resistance spot welding. The proposed approach examines the welding parameters and conditions known to have an influence on weld quality, and builds a quality estimation model step by step. The modeling procedure begins by establishing relationships between welding parameters (welding time, welding current, electrode force and sheet metal thickness), welding conditions represented by typical characteristics of the dynamic resistance curve and welding quality indices (nugget diameter, nugget penetration, and indentation depth), and the sensitivity of these elements to the variation of the process conditions. Using these results and various statistical tools, three estimation models are developed. The first one is based exclusively on welding parameters. The second model is based on characteristics of the dynamic resistance curve. The third estimation model combines welding parameters and characteristics of dynamic resistance curves. In order to carry out the models building procedure, an extensive number of welding experiments are required. For this purpose, Taguchi’s efficient method of experimental planning is adopted. The results demonstrate that the developed models can provide an accurate on-line estimate of the weld quality, under different welding conditions.
Authors: Yi Min Tu, Ran Feng Qiu, Hong Xin Shi, Hua Yu, Ke Ke Zhang
Abstract: In order to obtain better understanding of the resistance spot weldability of magnesium alloy and provide some foundational information for improving mechanical properties of the magnesium alloy joint, the influencing factors of pore formation during resistance spot welding of magnesium alloy, such as preexisting pores in base material, hydrogen rejection, shrinkage strain and expulsion, were analyzed; the corresponding restraining measures were discussed. The analyses reveal that the shrinkage strain and expulsion are important factors in contributing to the formation of pores during resistance spot welding of magnesium alloy, and that the pore formation could be suppressed by adjusting welding parameters.
Authors: Nai Feng Fan, Zhen Luo, Yang Li, Wen Bo Xuan
Abstract: Resistance spot welding (RSW) is an important welding process in modern industrial production, and the quality of welding nugget determines the strength of products to a large extent. Limited by the level of RSW quality monitor, however, RSW has rarely been applied to the fields with high welding quality requirements. Associated with the inversion theory, in this paper, an electromagnetic inverse model of RSW was established, and the analysis of influence factors, such as the layout of the probes, the discrete program and the regularization method, was implemented as well. The result shows that the layout of the probe and the regularization method has great influence on the model. When the probe is located at the y direction of x-axis or the x direction of y-axis and Conjugate Gradient method is selected, a much better outcome can be achieved.
Authors: Bin Wan, Xin Bin Hu, Shi Jie Dong, Zhong Hou Liu, Mao Zhang, Ning Hong Zhang
Abstract: In this paper, the control method of current gain compensation for welding is adopted. Precise current gain curves (i.e., current step curves) in resistance spot welding of galvanized steel plated are discussed and drawn. By analysis of failure of electrode cap, it indicates that new current step curve ensure that qualified welding spot nugget dimension is acquired. The welding spot is high in strength, stable and reliable in quality. It is superior to original current step curve.
Authors: Yan Xi, Liang Gong, Cheng Liang Liu
Abstract: Resistance spot welding (RSW) has been extensively used as a sheet metal joining process, and the welding process identification is the essential issue for the design of high performance control strategy and set-up of a new welding schedule. However the RSW is a nonlinear time-varying uncertain process which couples the thermal, electrical, mechanical and metallurgical dynamics. To understand this complicated physical phenomenon an M-series pseudo-random electrical pattern is adopted to excite the RSW electrical-thermal dynamics and the thermal response is recorded according to the welding power outputs. Based on the experimental information the transfer function of an RSW electrical-thermal mechanism is identified, and the optimum model order and parameters are determined. Subsequently a control-oriented RSW model is established to explore the welding power control algorithm. The simulated results from the control model show their agreement with the experimental data, which validates its feasibility for corresponding welding control.
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