| 摘要 |
Provided is a method for producing a seamless tube, in which after a starting material to be extruded has been heated to a heating temperature T [° C.] satisfying the relationship of Formula (1) or Formula (2) depending on the outside diameter d0 [mm] thereof, the starting material is hot extruded by providing a solid lubricating glass between the starting material to be extruded and a die, whereby a transverse flaw on the outer surface in the top portion of tube can be prevented when hot extrusion is performed by using a starting material for extrusion having low deformability at high temperatures. When d0<200, T≦̸1250+1.1487×A−7.838×ln(t0/t)−10.135×ln(d0/d) . . . (1); when d0≧200, T≦̸1219+1.1487×A−7.838×ln(t0/t)−10.135×ln(d0/d) . . . (2), where A=L/Vav×1000 [insect. Vav=(V0+V0×&rgr;)/2 [mm/sec], &rgr;=(t0×(d0−t0))/(t×(d−t)), t0: wall thickness of starting material to be extruded [mm], d: outside diameter of extruded tube [mm], t: wall thickness thereof [mm], L: length of approach portion of die along extrusion direction [mm], and V0: ram speed [mm/sec]. |
