Design method of large-diameter thick-walled tube casting and extrusion compound forming mold cavity

The invention relates to a design method of a large-diameter thick-walled tube casting and extrusion compound forming mold cavity, and belongs to the technical field of large-diameter thick-walled tube casting and extrusion compound forming. The design method solves the technical problem that a microstructure of a formed part exists in the process of casting and extrusion compound forming of a large-diameter thick-walled tube is not uniform. According to the technical scheme, the design method for the large-diameter thick-walled tube casting and extrusion compound forming mold cavity comprisesthe following steps that (1) the parameters of an extrusion model cavity are determined; (2) the transition position of a core rod section is determined to ensure that the inner and outer walls of apipe fitting finish plastic deformation at the same time; and (3) the size parameter of the transition part of a core rod is determined. The design method has the advantages of low cost, high strength, good plastic toughness,