| 摘要 |
PURPOSE:To stably extrude even with many kinds of resins and under various running conditions by a method wherein lubricating pressure is developed with molten resin by providing a land on the apex part of the flight of a screw in order to prevent the apex part of the flight of the screw from contacting with the wall surface during the rotation of the screw. CONSTITUTION:A land 4 constituting a line, which is concentric to a screw-outer diametral circle 5 and the radius of which is slightly smaller than that of the screw-outer diametral circle 5, is provided on the apex part of the flight 2 of a screw at the front face side 21 of the flight with respect to the direction of rotation of the screw in the flight 2 of the screw. The screw 1 rotates in the direction indicated with the arrow (a). When the flight 2 is about to contact with the wall surface of a cylinder 3 due to the rotation of the flight 2, lubricating pressure is developed due to a molten resin by the land 4 or 4' between the apex part of the flight and the wall surface of the cylinder, resulting in preventing the flight 2 from contacting with the cylinder 3. |
