Influence of welding current shape on expulsion and weld strength of resistance spot welds

Podržaj, Primož; Polajnar, Ivan; Diaci, Janez; Kariž, Z.

doi:10.1179/174329306x101391

Cited by 33 publications

(21 citation statements)

References 12 publications

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“…Welding current in resistance spot welding is AC. A major defect for DC spot welding is expulsion, which is a consequence of incessant heat generation and high temperature and liquid pressure [17]. The dynamic resistance takes the sum of the bulk resistance of the two workpieces, and contact resistances at the faying surface and two electrode-workpiece interfaces.…”

Section: Introductionmentioning

confidence: 99%

Phase Change Effects on Transport Processes in Resistance Spot Welding

Wei

Hsieh

2011

J. mech.

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The effects of distinct properties during phase change on mass, momentum, energy, species, and magnetic field intensity transport in workpieces and electrodes in the course of heating, melting, cooling and freezing periods in AC (alternative current) resistance spot welding are realistically and extensively investigated. Resistance spot welding has been widely used in joining thin workpieces due to its light weight and easy manufacturing. This study accounts for electromagnetic force, heat generations at the electrode-workpiece interface and faying surface between workpieces, and dynamic electrical resistance taking the sum of temperature-dependent bulk resistance of the workpieces and contact resistances at the faying surface and electrode-workpiece interface. The contact resistance is a function of hardness, temperature, electrode force, and surface condition. Instead of dealing with specific materials, this work is a general dimensionless investigation of resistance spot welding of materials with different specific heat and thermal conductivity ratios subject to realistic working parameters. The computed results show that nugget formation is delayed and heat transfer is reduced by increasing solid-to-liquid thermal conductivity and liquid-to-solid specific heat ratio. The corresponding thermal fields and flow patterns are also presented.

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Section: Introductionmentioning

confidence: 99%

Phase Change Effects on Transport Processes in Resistance Spot Welding

Wei

Hsieh

2011

J. mech.

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“…[2][3][4][5][6] Among these variables, the dynamic resistance and electrode displacement provide the most significant piece of information concerning the nugget formation and its growth in both the coated and the uncoated steel. The dynamic resistance, which is easily obtained, can be used in a production environment, while the electrode displacement is more suitable for a research environment.…”

Section: Introductionmentioning

confidence: 99%

Real Time Monitoring Weld Quality of Resistance Spot Welding for Stainless Steel

Wen

Wang

et al. 2009

ISIJ Int.

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“…Hence, there is only one input during each control cycle. In reality, Podržaj et al (2006) pointed out that different combinations of firing angles and welding transformer settings can result in different welding current waveforms, which can significantly affect the welding quality, as well as behaviors such as expulsion, even when the average values of the welding currents are the same. However, the integrated RSW system is nonlinear and varies over time; this is caused by the electrical system involved in the inductive loads.…”

Section: Introductionmentioning

confidence: 99%

Constant current vs. constant power control in AC resistance spot welding

Zhou

Yao

Cai

2015

Journal of Materials Processing Technology

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a b s t r a c tConstant current control (CCC) and constant power control (CPC) are two of the most popular control strategies employed in resistance spot welding (RSW). They have their individual respective advantages; for example, with CCC, it is easy to control energy delivery, while CPC can deliver more heat in particular situations. CPC can be accomplished by means of CCC. The performance of CPC is not as good as that of CCC, because CPC involves more interfering elements. Dynamic resistance is employed to analyze the welding process. Corresponding analysis shows a more reliable welding process can be obtained and the first melting point can be detected earlier when CCC is employed rather than CPC. Though the overall nugget growth trends may show a very small difference when using one strategy versus the other, CCC can provide a larger nugget size because the initial energy allotment is more reasonable and the energy delivery is much steadier. We conducted experiments to validate all of the theoretical analysis. This work can serve to inform actual welding production to obtain a more reliable welding process, enable welders to choose a proper control strategy and help improve energy efficiency in practice.

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Influence of welding current shape on expulsion and weld strength of resistance spot welds

Cited by 33 publications

References 12 publications

Phase Change Effects on Transport Processes in Resistance Spot Welding

Phase Change Effects on Transport Processes in Resistance Spot Welding

Real Time Monitoring Weld Quality of Resistance Spot Welding for Stainless Steel

Constant current vs. constant power control in AC resistance spot welding

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