Square pipes welding

From welding square tube deformation theory shows that the impact of welding deformation square tube size is a major factor: the larger the size of weld, weld more metal, the greater the deformation; weld sizes are equal, the greater the weld heat input, resulting in deformation greater; welded square tube big long weld time, welding deformation segment is smaller than the straight; welds arranged asymmetric or symmetric, but asymmetric arrangement, although welded pipe, welds more serious deviation, the greater the deformation; The smaller component rigidity, the greater the deformation.

Welded square tube specifications through process test and process analysis to determine the welded square tube butt weld with double CO2 gas shielded arc welding. The first layer of weld welding square tube current of 200 ~ 250A, the second layer is 240 ~ 320A; arc voltage is 24 ~ 26V. Process requirements are: first layer of weld penetration must ensure that the back forming good; square tube welding current, arc voltage, wire feed speed and welding square tube speed can be adjusted according to the device model.

Welded square tube order to reduce distortion, rectangular welded square tube butt welding sequence according to the following principles: taking from the middle to both sides of the hierarchical segmentation symmetrical jump welding, resulting in deformation of welded square tube welded smaller than straight, is conducive to stress dispersion and release, to avoid the complexity of the stress in the weldment. Straight swing welding, the narrower plastic deformation zone formed welded square tube emergence started only once, and because of continuous welded square tube swing, heat input capacity, heated area, large plastic deformation zone is caused by compression, thus welding after the shrinkage deformation great.

When hierarchical segmentation jump welding, very small section of each layer, the heat required is small, and each layer is divided into several segments jump welding, soldering each section are basically re-established once the temperature field on a cold steel every time the emergence of a narrow zone of plastic deformation, and thus the average width (ie, transverse shrinkage of size) plastic deformation zone than the corresponding straight layered welding small, longitudinal shrinkage is small, compared to the once-through continuous fill swing welded square tube distortion even smaller.