Welding Deformation And Control Of Box-shaped Container Circular Flange-plate-shell Structure

Welded seams with closed circuits(closed weld)are often introduced in the manufacture of container shell structures due to the hatch,flange,manhole,takeover and other structural settings and connections.These closed circular butt welds or fillet welds have a hollow and circular hole in the middle,although closed welds are generally welded in the larger restraint welding conditions,the presence of intermediate holes can reduce the degree of restraint in the welding of closed welds,the welding plate with smaller thickness is prone to buckling deformation in the position of the middle hole after welding,which affects the assembly precision and serviceability of the welding component.A large box-shaped container plant circular flange-plate-shell structure which manufactured by a factory is a typical welded structure with a closed weld,the flange-plate-shell structural characteristics of the large-span box-shaped container and large-size circular flanges exacerbate the degree of deformation after welding.In this paper,the finite element simulation software was used to simulate the welding process of long-span thin-plate structure with large-size circular flanges,the deformation characteristics of circular flange-plate-shell structure after welding were studied,the deformation control measures which based on the analysis of the deformation mechanism such as increasing the structural rigidity and optimizing the welding sequence were put forward,and simulation methods adopting examined the effect of deformation control.Research shows that:1.Flange-plate-shell structure in various regions after welding to produce varying degrees of collapse deformation,among them,the maximum collapsing displacement of 6.184 mm lies in the inner circle of the flange circle,the maximum collapse displacement of the flange circumference outer ring is 4.790 mm,the difference between the maximum collapse displacement of the flange circumference of the inner ring and the outer ring(flange flatness)is 1.797 mm,which is shown as the internal concave buckling deformation of the flange.In addition,the outer ring of the flange maximum/minimum diameter difference is 4.080 mm,that,roundness is 2.040 mm after welding flange roundness is worse.2.The reason for the deformation of the flange-plate-shell structure is related to the radial contraction and circumferential contraction of the annular fillet weld after welding.The radial shrinkage of the annular fillet weld(transverse contraction)causes the transverse contraction of the surface of the fillet weld larger than that of the welding root and the lateral contraction of the surface of the slant panel to be larger than that in the interior,which cause the angular deformation of the flange and the shell structure.In addition,the large structural span and the large diameter intermediate hole reduce the restraint degree and the large weld foot size of 8 mm will increase the actual situation of heat input,which exacerbates the severity of angular deformation.Circular fillet weld circumferential shrinkage so that the circumferential weld tendencies tend to decrease.The effect of this is to introduce a compressive stress to the center of the circle in the annular region where the flange is located,which facilitates further tilting of the annular zone of the inclined top wall plate and concave deformation of the flange plate,at the same time,the slope of the top wall showed a slight buckling distortion.3.The measures of setting the temporary ring-shaped stiffeners in close contact under the flange-plate shell structure are as follows:the maximum collapse deformation,roundness and flatness after welding are respectively 2.612 mm,0.695 mm and 1.216 mm,The deformation is increased by 57.76%,65.93%,32.33%compared with the original welding scheme,flange buckling deformation is effectively controlled.4.Based on the temporary ring-shaped stiffeners with close contact under the flange-plate shell structure,segmented welding with different welding sequences was carried out.The comparative analysis showed that the segmented welding control was more than 60%of the original welding process,one of the best welding sequence after welding the maximum deformation,collapse roundness and flatness are respectively 1.583 mm,0.135 mm,0.689 mm,The deformation is increased by 74.40%,93.38%,61.66%compared with the original welding scheme.