The invention relates to a method for improving the wall-thickness uniformity during a large-sized thick-wall
pipe vertical hot
extrusion process. The method for improving the wall-thickness uniformity during the large-sized thick-wall
pipe vertical hot
extrusion process belongs to the technical field of large-sized thick-wall
pipe hot
extrusion forming, and comprises the process steps and control technical parameters as below: one end of a pipe blank to be extruded is processed to a specific shape; mold preheating temperature is set: for a heat-resisting steel material, the mold preheating temperature is 400 to 450 DEG C, and for a heat-resisting
alloy material, the mold preheating temperature is 350 to 400 DEG C; the pipe blank extrusion minimum limit temperature is controlled: for the heat-resisting steel material, the extrusion minimum limit temperature is 1,000 to 1,010 DEG C, and for the heat-resisting
alloy material, the extrusion minimum limit temperature is 1,030 to 1,040 DEG C; and reasonable glass
lubricant type and
granularity are selected according to extrusion characteristics of different positions. The method for improving the wall-thickness uniformity during the large-sized thick-wall pipe vertical hot extrusion process has the advantages that the
metal uniformity flow of the pipe blank during a stable extrusion process is greatly improved, the wall-thickness uniformity during the large-sized thick-wall pipe hot extrusion process is remarkably improved, meanwhile, the cost of raw materials is saved by 20 percent, the service life of a mold is prolonged by 20 percent, the labor productivity during the extrusion process is improved by 15 percent, and about 70 percent of
workload of follow-up
cutting processing is reduced.