The Role of Lug Preheating, Melt Pool Temperature


Abstract :

This work deals with effective parameters in the cast-on-strap (COS) process during which gridlugs of a lead-acid battery are joined together by a strap. The effects of lug preheating, melt pool temperature, and lug entrance delay on the quality of joints and casting defects were investigated.

Lug preheating was found to propitiously reduce joint internal voids because of flux elimination. Its adverse effect on lowering lug wettability, however, made it unfavorable under the experimental conditions. The melt pool temperature also showed a two-sided effect depending on the process conditions. Raising the temperature increases the strap melt fluidity,

which improves the joint contact area; however, it has a negative effect on lug wettability by flux evaporation. Besides, higher temperatures cause more lug back-melting and, hence, lower relative contact lengths. Therefore, an intermediate temperature of 683 K (410 _C) was found to make the most proper condition. Moreover, the case at which the lugs enter the mold coincident with its filling by the melt rendered the best joint quality. In this condition, the melt flows through the interlug spaces, which helps the voids to escape, resulting in the better joint interface. As the conclusion, the lug entrance time has the most effective role on joint quality, considering that lug preheating does not show any improving effect.

Introduction :

It is hardly possible to find a transport vehicle on the street operating using something other than a lead-acid battery. Despite the availability of alternative electrochemical storage systems that may have higher specific energy and efficiency, lead-acid batteries are still the world’s most important rechargeable power source.

This is because the life and cost play a key role in all industrial applications