Perimeter elastic control method for common-bottom suit and welding method for welding common-bottom suit and cylinder section

The invention provides an elastic perimeter control method for a common-bottom set and a welding method for welding the common-bottom set with a cylinder section, which comprises the following steps: S1, processing a common-bottom lock bottom groove and blanking and welding the cylinder section by mounting on a foundation for coaxial processing, firstly turning the perimeter of the common-bottom lock bottom groove in place, and then turning the perimeter of the common-bottom lock bottom groove in place; the inner perimeter of the welding side of the cylinder section lock bottom is subjected to blanking welding according to a sleeving gap, and the assembly working condition of negative interference is achieved through matching of the perimeter of the cylinder section and the perimeter of the common-bottom lock bottom groove; s2, the common bottom and the barrel section are matched in a sleeved mode through the perimeter gap; and S3, after the common bottom and the cylinder section are sleeved in place, the int