Integral forming method for large-size thin-walled ring shell

An integral forming method for a large-size thin-walled ring shell, comprising the following steps:

• step 1:
• analyzing characteristics of a target part, and determining a forming scheme and the size of a cylinder billet;
• firstly, analyzing characteristics of the target part, and determining the cross-sectional shape and size of the cylinder billet;
• secondly, analyzing the influence of a weld seam when bending and forming the cylinder billet, and determining a position of the weld seam;
• finally, predicting the generation and distribution of wrinkling defects in the forming step by simulation, and further optimizing the shape, size and forming process parameters of the cylinder billet and each preform according to simulation results;
• and placing the axial weld seam and the wrinkling defects of the cylinder billet in a process segment, and cutting off the process segment with the weld seam and the wrinkles after forming, so as to obtain a thin-walled ring shell meeting the requirements for shape and size;
• step 2:
• manufacturing a straight cylinder billet;
• according to the analysis results of step 1, determining the material and size of a sheet billet, and manufacturing the sheet billet into the straight cylinder billet by roll welding;
• step 3:
• bending the straight cylinder billet to make both end faces thereof butted and welded into an enclosed ring-shaped prefabricated billet;
• step 4:
• carrying out local mold-constrained thermal expansion forming of the enclosed ring-shaped prefabricated billet;
• carrying out thermal expansion forming of the enclosed ring-shaped prefabricated billet obtained in step 3 in a local constrained expansion die;
• in the forming process, the expansion forming of local regions not fully formed of the enclosed ring-shaped prefabricated billet is achieved under the action of high temperature and high pressure, and the remaining unformed regions do not undergo plastic deformation due to low temperature;
• step 5:
• carrying out rotational progressive thermal expansion forming of the ring shell;
• rotating a local formed ring-shaped prefabricated billet obtained in step 4 by a certain angle, and continuing local constrained thermal expansion forming according to step 4;
• and repeating the step of local thermal expansion forming until each region of the ring shell meets design requirements;
• step 6:
• cutting off the process segment to obtain the target part;
• according to the characteristics of the target part, obtaining an integral ring shell component without cutting, or obtaining two open cross-sectional ring shell components by circumferential cutting, or obtaining a segmented enclosed cross-sectional ring shell component by radial cutting, or obtaining a segmented open cross-sectional ring shell component by circumferential and radial cutting.