Abstract: A screw shaft structure for a twin screw extruder includes a tapered section (20) provided between a ground section (6) and a screw piece inserting section (8), and a tapered ring (21) fitted onto the tapered section (20). The tapered ring (21) serves as a flange section. An object is to reduce the weight of raw material to be used for manufacturing a screw shaft by combining a tapered section and a tapered ring as a structure of a flange section.

Abstract: An object is to reduce a weight of a raw material to be used for manufacturing a screw shaft by combining a tapered section and a tapered ring as a structure of a flange section. A screw shaft structure for a twin screw extruder includes a tapered section (20) provided between a ground section (6) and a screw piece inserting section (8), and a tapered ring (21) fitted onto the tapered section (20), the tapered ring (21) serving as a flange section.

Abstract: A cylinder 2 is formed with an upper guide bore 10a and a lower guide bore 10b at a position corresponding to a gate part B. Gate rods 7 are rotatably inserted through the guide bores 10a, 10b, respectively. Each of the gate rods 7 is formed with opening degree changing recesses in a form of an opencut adjacent to each other in an axial direction in order to constitute opening degree variable channels S in combination with opening degree variable channel forming parts 14 of two screws 3. Each of the recesses 11 consists of a first semicircular face 12 and a second semicircular face 13 in such a shape that an upstream side end of the first semicircular face 12 is diagonally cut.