A Prediction of the Penetration Depth on CO₂Arc Welding of Steel Sheet Lap Joint with Fillet for Car Body using Multiple Regression Analysis Technique

摘要

Welding is an essential process in the automotive industry. Most welding processes that are used for auto body are spot welding and <TEX>$CO_2$</TEX> welding are used in a small part. In production field, <TEX>$CO_2$</TEX> welding process is decreased and spot welding process is increased due to welding quality is poor and defects are occurred in <TEX>$CO_2$</TEX> welding process frequently. But <TEX>$CO_2$</TEX> welding process should be used at robot interference parts and closed parts where spot welding couldn't. Because of the 0.65mm ~ 2.0mm thickness steel sheet were used in the automotive industry, poor quality of welding area such as burn through and under fill were happened frequently in <TEX>$CO_2$</TEX> process. In this paper, we will study about the penetration depth which gives a huge impact on burn through changing a degree of base metal, welding position and torch angle. Voltage, current and welding speed were fixed but degree of base metal, welding position and torch angle were changed. And Cold- Rolled(CR) steel sheet was used. Penetration depth was analysed by multiple regression analysis to derive approximate calculations. And reliability of approximate calculations were confirmed through additional experiments. As the results of this research, we confirmed the effect of torch and plate angle to bead shape. And we present a possibility that can simulate more accurate to weld geometry, as deduced the verification equations that has tolerance of less than 21.69%.