绝缘片约束TIG电弧在窄间隙中的加热特性

Heating characteristic of constricting TIG arc with insulating plate in narrow gap welding

采用坡口侧壁放置绝缘片的方式约束电弧,在4 mm宽的I型坡口内进行窄间隙TIG焊接试验,通过分析坡口截面各区域熔化面积及其所占比例的变化,研究绝缘片约束TIG电弧的加热特性.结果表明,窄间隙中依靠绝缘片对弧根的固壁约束作用能够将电弧加热区域限制在坡口底部,增强电弧对坡口底部和底角的加热效果,防止电弧集中于侧壁燃烧;弧长、绝缘片对弧根的约束程度和焊接电流三者匹配时,可使坡口底角获得可靠熔合;弧长过长会导致电弧直接向侧壁攀升,且无法依靠绝缘片将电弧控制在坡口底部;绝缘片对弧根约束过多以及采用较大的焊接电流,均会导致电弧将绝缘片熔化,造成电弧燃烧不稳定.

TIG arc was constricted by insulating plate covering onto side wall of square groove 4 mm in width in the narrow gap welding test.The heating characteristic of TIG arc was analyzed by various melting regions area of groove cross section and their proportion.The results indicate that the constricting action of insulating plate on arc root can restrict the arc in the bottom of square groove to intensify the heating effect on corner,and prevent the arc burned on the sidewalls.The arc length,intensity of constriction effect on arc root and welding current are matched with each other to make the sidewall roots bonded with sidewall of groove,When the arc length is too long,the arc will climb up along the sidewall directly and cannot be stopped by insulating plate.The excessive constriction effect on arc root and high welding current can result in the insulating plate melting,and the arc is instable.