Large-diameter thick-walled pipe hot extruding die taper angle and casting blank size determining method

The invention discloses a large-diameter thick-walled pipe hot extruding die taper angle and casting blank size determining method and belongs to the field of difficult-to-form alloy steel large-diameter thick-walled seamless steel pipe hot extruding machining forming design. The method is characterized by being design in the following steps that (1) the die taper angle alpha is determined according to the extrusion ratio lambda of large-diameter thick-walled pipe hot extruding; (2) the wall thickness b of a casting blank is determined according to the extrusion ratio lambda; and (3) the length h of the casting blank is determined according to the sizes, including the inner diameter 2r0, the wall thickness B, the pipe length H, the extrusion ratio lambda, the die taper angle alpha and the wall thickness b of the casting blank, of a large-diameter thick-walled finished pipe. The method has the advantages that the optimal die taper angle without dead zones is rapidly determined, and the performance of an extrud