| 摘要 |
PURPOSE:To reduce eccentricity of a screw which is caused by unbalanced force generated at the top of a flight by broadening the flight breadth of the screw in the starting part or the finishing part of a barrier and making the top of the flight to a shape in which its diameter gradually increases toward the direction of rotation of the screw. CONSTITUTION:The flight breadth (W+W') of the starting part I or the finishing part II of a barrier part or both parts I, II is made broader than the breadth of a main flight 1 of two groove parts or a subflight. Furthermore the top of this flight having the broad breadth is made to a shape in which its diameter gradually increases toward the direction of rotation of a screw. In other words, it is made to such a shape that the clearance between the circumscribed circle of the screw and the top of the flight of the circumference thereof gradually decreases. As a result, the large lubrication pressure of fluid is generated by fused resin in the starting part I and the finishing part II and eccentricity of the screw which is caused by unbalanced force generated in this part is made small and scoring wear is prevented. |
