Multi-lumen tube extrusion molding apparatus

An extrusion molding apparatus for a multi-lumen tube having two or more conduits, the multi-lumen tube extrusion molding apparatus comprising:

• a resin supplying portion that extrudes a molten resin;
• a die that has an extrusion port at a lower end portion and molds the multi-lumen tube as the resin supplied from the resin supplying portion is extruded vertically downward;
• an outer surface molding apparatus that molds an outer surface of the multi-lumen tube extruded from the die;
• a gas supplying apparatus;
• and
• a depressurizing apparatus, wherein
• the die includes
• an inner die,
• two or more conduit molding members of tubular shapes that are provided in correspondence with the respective conduits of the multi-lumen tube and with each of which a front end portion projects from a lower end portion of the inner die and a remaining portion is positioned in an interior of the inner die and each having a penetrating hole and having, at the front end portion, a portion of outer shape corresponding to a cross-sectional shape of the corresponding conduit, and
• an outer die of tubular shape that surrounds the inner die and the portions projecting from the lower end portion of the inner die and forms a resin flow passage between its inner surface and an outer surface of the inner die,
• the outer surface molding apparatus includes
• a plurality of first mold blocks each having a flat surface with which an outer shape is a rectangular shape, a groove of rectilinear shape that is provided on the flat surface and with which a cross section in a direction orthogonal to the flat surface is a semicircular shape, and a slit or a pore that penetrates through the groove,
• second mold blocks of the same shape and same number as the first mold blocks;
• and
• a driving mechanism that pairs and circulates the first mold blocks and the second mold blocks,
• the driving mechanism
• causes, in a molding zone provided vertically below the die, the flat surfaces of each paired first mold block and second mold block to be in surface contact with each other such that the grooves thereof overlap mutually, a molding space with which a lateral cross section is of a perfect circular shape and a center of the lateral cross section coincides substantially with a central axis of the die to be formed between the mutually overlapped grooves, and a successive plurality of pairs of the first mold block and the second mold block to undergo rectilinear movement vertically downward along the central axis of the die and
• causes, outside the molding zone, each paired first mold block and second mold block to separate from each other, and
• in a state in which the resin is supplied from the resin supplying portion to the die,
• a gas is supplied from the gas supplying apparatus to each of the conduit molding members, the supplied gas is injected from front ends of the penetrating holes,
• the driving mechanism causes, in a state in which the multi-lumen tube extruded from the die is contained in the molding space of each of the successive plurality of pairs of the first mold block and the second mold block, the first mold blocks and the second mold blocks to move vertically downward in accordance with the extrusion of the multi-lumen tube, and
• the molding space is depressurized by the depressurizing apparatus to put the outer surface of the multi-lumen tube contained in the molding space in close contact with inner surfaces of the grooves.