When large thick-walled pressure vessel heads are manufactured, they are often formed by split-pressing and tailor-welding the head blank. The head is composed of a large ball apex and multiple curved petals, and the ball lobes and curved lobes are first cold formed and stamped.

　　Finally, the assembly welding is carried out on the body of the welding matrix, and the schematic diagram is shown in the figure below.

　　The technological process is as follows: confirming the blank material of the tailor-welded head-blanking according to the shape of the head-hot stamping-heat treatment-ultrasonic

　　Inspection—Crosscutting and cutting—Cutting allowance—Processing weld bevel—Assembly head—Welding head—Appearance inspection, correction, and non-destructive testing of magnetic particle inspection.

　　This forming method can form a larger-sized head with a smaller pressure machine, but there are some shortcomings such as head split-plate design, complex calculation and blanking, long process route, many kinds of molds, high cost, large amount of work, and not easy to guarantee the precision after welding.