| 摘要 |
A screw pair includes first and second screws (14a, 14b) each having an outer peripheral surface (9) in which a groove (8) is helically formed, and transports a starting material in an X1 direction along the axis. The inner side surface of the groove (8) of each of the screws (14a, 14b) includes a first surface (8a) facing the X1 direction and formed such that the outer peripheral surfaces (9) of the screws (14a, 14b) are fitted with no clearance therebetween in the state where the screws (14a, 14b) mesh with each other, and a second surface (8b) facing an X2 direction opposite to the X1 direction and forming a clearance between the outer peripheral surfaces (9) of the screws (14a, 14b) in the state where the screws (14a, 14b) mesh with each other. |
