Theoretical analysis of shunting effect in resistance spot welding (RSW) of AA2219

Abstract Few aspects of shunting effect have been studied so far. Shunting effect in resistance spot welding (RSW) occurs when the electrical current passes through the previous spot welds. Value of this current depends mostly on distance, number, and size of previous spot welds. This will cause some dimensional and metallurgical changes in welding nugget as well as heat affected zone (HAZ). In this study, shunting effect of RSW is considered by finite element method (FEM) and the results are compared to experiments performed on aluminum alloy 2219. Weld spacing together with welding current and time are considered to discover the effect of shunting current in the final quality of nugget. A three factor experiment design has been performed to find the significance of factors and interactive effects, as well as finite element model verification. Electrothermal and mechanical interactions are considered in the FEM. Experimental and numerical solutions have yielded similar results in terms of welding nugget properties. Asymmetry in electrical potential, temperature, stress distribution and geometry of shunted nugget is predicted and verified directly or indirectly. Intense effect of shunting current on nugget height, asymmetric growth of heat affected zone (HAZ) toward previous welding nugget, as well as concentration of alloying elements along grain boundaries are also discovered.

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Impact of the Winding Arrangement on Efficiency of the Resistance Spot Welding Transformer

Energies ◽

10.3390/en12193735 ◽

2019 ◽

Vol 12 (19) ◽

pp. 3735

Author(s):

Gašper Habjan ◽

Martin Petrun

Keyword(s):

Theoretical Analysis ◽

Resistance Spot Welding ◽

Power Loss ◽

Spot Welding ◽

Experimental System ◽

Magnetic Core ◽

Design Guidelines ◽

Resistance Spot ◽

Analysis Design ◽

The Impact

In this paper, the impact of the winding arrangement on the efficiency of the resistance spot welding (RSW) transformer is presented. First, the design and operation of the transformer inside a high power RSW system are analyzed. Based on the presented analysis, the generation of imbalanced excitation of the magnetic core is presented, which leads to unfavorable leakage magnetic fluxes inside the transformer. Such fluxes are linked to the dynamic power loss components that significantly decrease the efficiency of the transformer. Based on the presented analysis, design guidelines to reduce the unwanted leakage fluxes are pointed out. The presented theoretical analysis is confirmed by measurements using a laboratory experimental system. The presented experimental results confirm that the proposed improved winding arrangement increased the efficiency of the transformer in average for 6.27%.

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Adaptive Resistance Spot Welding Process that Reduces the Shunting Effect for Automotive High-Strength Steels

Metals ◽

10.3390/met8100775 ◽

2018 ◽

Vol 8 (10) ◽

pp. 775 ◽

Cited By ~ 6

Author(s):

Jiyoung Yu

Keyword(s):

Heat Input ◽

Resistance Spot Welding ◽

Spot Welding ◽

Welding Process ◽

Vehicle Body ◽

Logistic Growth ◽

Power Curve ◽

Resistance Spot ◽

Welding Heat Input ◽

Shunting Effect

Although short-pitch resistance spot welding (RSW) significantly increases vehicle body strength, its application has been limited because of the associated shunting effect. In this study, a reference-based adaptive RSW process intended to minimize the shunting effect was proposed, and a related RSW system that controls welding current and power was developed to implement the adaptive method. The proposed RSW method compensates for the heat input loss caused by the shunting effect based on the estimated weld pitch and reference data obtained under suitable welding conditions. An exponential model was developed using a unique indicator (i.e., the ratio of the adaptive welding heat input to the reference welding heat input until the reference welding power curve peak) to estimate the weld pitch. A logistic growth model was next developed based on the relationship of the nugget diameter, heat input, and weld pitch to estimate the heat input compensation. A unique strategy using power control with a modified reference power curve was applied to supply the calculated heat input compensation. The experimental results intended to validate the proposed adaptive RSW process indicated that the proposed process effectively reduced the shunting effect and produced an improved nugget shape relative to the conventional RSW process.

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