| 摘要 |
PURPOSE:To extrude a resin in a uniform molten state, by a method wherein a small diameter part is provided to the leading end of a screw to reduce the inner diameter of the leading end of a barrel and projections each having a specific size is provided to the peripheral surface of the small diameter part of the screw so as to be made discontinuous in the circumferential direction and the length of the notch between the projections in the circumferential direction is specified. CONSTITUTION:A screw 2 has a small diameter part 6 at the leading end thereof and a large number of projections 9 are formed to the circumferential surface of the small diameter part 6. The inner surface of the inner diameter reduced part 7 of a barrel is close to the leading ends of the projections 9 and the inner diameter reduced part 7 is extended so as to be made slightly longer than the small diameter part 6 in the axial direction of the screw 2. The projections 9 are separated into many ones so as to be discontinuous in the circumferential direction of the small diameter part 6 and the length (x) of each projection is 1/3 or less the circumference of the small diameter part and the length (y) thereof in the axial direction of the screw is the radius (r) or less of the small diameter part 6. Notches 15 are formed between the projections 9 and the length of each notch in the circumferential direction is set to 1/20-1/3 the circumferential length. By this method, an extruder uniformly mixing a resin and preventing the local generation of heat and suitable for forming resin foam is obtained. |
