港口机械箱梁Ⅰ型坡口大间隙不清根焊接新技术

New technology of large gap non-back-gouging welding of i-groove of port equipment box girder

中厚板拼接焊缝在港口机械箱梁中广泛应用,传统的Ⅴ型坡口清根焊接的生产效率低下,提出一种针对坡口切割质量差、装配精度不高的Ⅰ型坡口新方法。文中针对Ⅰ型坡口等离子切割造成自然坡口,装配时存在大间隙、不等间隙等现象造成焊接质量不稳定,易出现缺陷的现象,探索不同间隙下等离子切割的Ⅰ型坡口焊接新方法即正面实心焊丝打底+正面埋弧焊+背面埋弧焊。研究结果表明:在根部间隙1～3 mm下,采用小电流150～220 A实心焊丝气保护焊打底,小电流400～550 A正面埋弧焊,背面采用较大电流600～750 A埋弧焊施焊,可实现不等间隙不清根Ⅰ型坡口焊接。

The medium plate welding seam is widely applied to the port equipment box girders,but the traditional Ⅴ-groove back-gouging welding is of low production efficiency.The paper puts forward a new method regarding Ⅰ-groove to deal with low quality of groove cutting and low accuracy of assembly.Aiming at certain problems such as instable welding quality and possible defects resulting from the natural groove by I-groove plasma cutting,large and unequal gaps during assembly,a new method of I-groove welding by plasma cutting in different gaps is studied,namely front GMAW with solid wire + front SAW +back SAW.The study result shows that in case of root gap within 1~3 mm,the low current 150~220 A is used for GMAW,with the current 400-550 A for front SAW and the high current 600~750 A for back SAW,which can realize non-bac-kgouging I-groove welding in different gaps.