| 摘要 |
An extrusion mandrel assembly for continuous extrusion apparatus has a lobed, mushroom shaped, dolly (28) formed with a central spacing stem (30) located in the chamber (16) adjacent a pair of discharge ports (27) connecting respective exit apertures (10) into an internal cavity in the chamber (16) and a pair of shaped lobes (32) having rear faces (34) extending from the central spacing stem (30), outer edge portions (36) and front faces merging inco a collar (38) around a neck (40) co-acting with an annular shoulder (42) on the extrusion die body (20) to form an annular extrusion gap (44), with each of the lobes (32) being profiled such that frictional surface drag on extruding material is substantially uniform around the lobed dolly (28). Individual paths between the discharge ports (27) and the annular extrusion gap (44) are substantially equal in length as measured on the respective surfaces of the rear faces, edge portions and front faces of the profiled lobes (32). An extruded aluminium cylindrical tube of up to 150mm diameter and wall thickness in the range from lmm to 4mm may be formed avoiding discontinuities. |
