EXTRUSION DIE AND EXTRUSION METHOD

PROBLEM TO BE SOLVED: To provide an extrusion die capable of thinning an inner layer and reducing a thickness distribution in a thermoplastic resin tube having a multilayer structure, and an extrusion method. SOLUTION: An inner layer uneven thickness adjustment means 8 of the extrusion die 1 has four joined bolts 28 which are circumferentially disposed at predetermined intervals and joins an adapter 2, a flange 3a of an inner layer core 3 and a cylinder 6, and a clearance C of a predetermined size is formed at a tip end side of the surface of the flange 3a of the inner layer core 3 in such a state that the surface of a base end side of the outer layer core 4 is brought into contact with the surface of the tip end side of the flange 3a of the inner layer core 3. The axis line of the inner layer core 3 and the axis line of the cylinder 6 can be relatively inclined, and an uneven thickness adjustment of the inner layer can be performed by adjusting the respective fastening amount of the plurality of bolts 28. COPYRIGHT: (C)2009,JPO&INPIT