Mathematical Modeling of Electrode Cooling in Resistance Spot Welding
Due to the high heat flux from the weld nugget to the electrode, the electrode experiences thermal excursion and deformation, which lead to the requirement for frequent redressing or replacement of the weld cap. To extend the life of the weld cap, a better understanding of the thermal excursion experienced by the weld cap, and thus its cooling, is required. In this study, mathematical models that include the cooling water flow impinging onto the underside of the cap, resistance (or Joule) heating, as well as the heat transfer between the weld cap and the cooling water were developed. It was found that the conventional weld cap configuration results in a severe stagnation fluid flow near the underside of the weld cap and thus may lead to poor film boiling heat transfer there. Based on this understanding, a new cone-fin design on the underside of the weld cap was proposed to enhance the heat transfer. Our modeling results show that the fin not only lessens the stagnation flow near the cap but also increases the cooling area, leading to large reductions in temperatures at the underside of the weld cap. A roughened fin surface is also suggested to provide nucleation sites that can enhance the heat transfer between the cap and the cooling water due to nucleate boiling. Our implementation studies further confirm that the new cone-fin cap design can significantly extend the life of the weld cap.
Z. H. Rao et al., "Mathematical Modeling of Electrode Cooling in Resistance Spot Welding," Welding Journal (Miami, Fla), American Welding Society, Jan 2009.
Mechanical and Aerospace Engineering
Keywords and Phrases
Electrode Cooling; Resistance Spot Welding; Transient Thermal Analysis; Weld Cap
Article - Journal
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