DIE FOR EXTRUSION OF HOLLOW PRODUCT

PURPOSE:POSE: To uniformize the quality by forming in a die and port a spigot part corresponding to each cavity, forming a recessed part on a face opposite from the side face of the die of the port correspondingly to each port hole and thereby preventing uneven thickness and the ununiform flow velocity of a billet. CONSTITUTION:Since a die 2 and a port 3 are joined by a spigot part 11, 12 at the center and its outer peripheral part, the center part of the port 3 is not deformed to the die 2 side nor a mandrel 7 is inclined by receiving a pressing force from a billet 9 at the time of extrusion. In addition, the recessed part 13, 14 formed in the port 3 is entered by the billet 9 when it 15 flowed in to each port hole 8A, 8B. At that time, even if the flow velocity of the billet 9 entering 8A side is faster than that of the billet 9 entering 8B side, the reduction of the billet 9 quantity flowing in the port hole 8B or the reduction of the flow velocity is prevented. Thus, a hollow extruded product is obtained for a uniform quality.