Abstract: To provide a kneading screw which can reduce such a phenomenon that a disproportional load is imposed onto a shaft of the kneading screw without degrading kneading performance of the kneading screw, a twin screw extruder with the kneading screw, and a method for assembling the kneading screw.

Abstract: The kneading disc segment according to the present invention comprises plural disc sets each comprising two kneading discs and mounted on a kneading screw (3) which is for kneading a material while feeding the material to a downstream side. Disc sets each comprising a first kneading disc positioned on an upstream side and a second kneading disc, the second kneading disc being mounted continuously with and downstream of the first kneading disc so as to have a phase difference ? of an acute angle relative to the first kneading disc, are disposed continuously in the axial direction of the kneading screw. The first kneading discs in two continuous disc sets have a phase difference of 180°. With this construction, it is possible to attain a higher degree of kneading than in the conventional neutral kneading disc segment.

Abstract: One object of the present invention is to provide a kneader which can diminish wear of screws and a barrel while preventing the manufacturing process for the screws and barrel from becoming complicated. In this kneader, a pair of screws are rotated about respective axes thereof to knead a material to be kneaded which is introduced into a kneading space formed within a barrel. Each screw has such a shape generating deflection in a predetermined direction perpendicular to an arranged direction of the axes of the pair of screws during kneading of the material to be kneaded, and the kneading space has a shape such that a pair of accommodating spaces which accommodate each of the screws respectively are connected together so as to overlap each other partially in the radial direction, each accommodating space being formed in such a manner that the diameter thereof in the predetermined direction in which there occurs deflection of each screw is larger than in any other direction.