| 摘要 |
PURPOSE:To increase an extrusion quantity by reducing extrusion resistance of molten resin of a parallel part of a land and an extrusion mold for a tubular body free from a memory effect of an elastic deformation is obtained, by a method wherein the parallel part of the land possesses at least two parallel parts where a gap between an outer circumferential surface of an inner mold and an inner circumferential surface of an outer mold are different from each other and the closer the gap of the parallel part approaches an outlet, the smaller the gap becomes. CONSTITUTION:An inner mold 2 of an extrusion mold A for a tubular body is fixed to an outer mold 1 with spiders formed on a plurality of positions of a circumferential direction of a die main body 4. Although molten resin receives a memory effect of an elastic deformation in a contracting diametric part 31 or a spider 43, since a gap t2 of a parallel part 321 of an inlet side in a parallel part 32 of a land is large, a staying time of the molten resin at the parallel part becomes long and memory of an elastic deformation is mitigated sufficiently. Moreover, the center lines of the gaps t2, t1 are identical with each other substantially, a memory effect of the elastic deformation in drawing generated newly is extremely low and both elastic deformations at the parallel part 322 close to an outlet are mitigated completely. Consequently, resistance with the molten resin becomes low and an extrusion quantity can be improved. |
