| 摘要 |
PURPOSE:To prevent the separation or improper adhesion of a filter, by tensioning a filter in the central part of the inner periphery of a plastic tube in such manner as to embed the peripheral edge of the filter in the thick-walled part. CONSTITUTION:An ordinary tube injection molding metal die is dividable into at least upper and lower sections 1 and 1' across an axis thereof. Molten resin, to form an inner tube 6, is forced under pressure into the metal die through a gate 1'' thereof, with a filter 4, cut into a larger outside diameter than the inside diameter of the metal die and piercing an annularly-shaped part 4' facing the cavities 3 and 3' of the aforesaid dies with each of a plurality of small holes 5, held between the mating faces of the upper and lower metal dies. Thereafter, an outer tube molding metal die 8 having a larger inside diameter than the outside diameter of the filter 4 of the aforesaid inner tube 6 is set on the first-mentioned die and molten resin is further poured between the metal die 8 and the inner tube 6 to increase the pipe thickness, whereby a vent free from filter separation or the improper adhesion can be produced. |
