| 摘要 |
PURPOSE:To provide a multi-shaft extruder screw of good gripping at feed portion and reduced back flow by engaging right and left turning screws of specified constitution with each other. CONSTITUTION:A right turn screw 11 having a large flight groove width and a small thread width is engaged perfectly with a left turn screw 12 having a large flight thread width and a small groove width. The screw 11, similar to a single- shaft screw, has a function of feeding a raw material resin forward. The screw 12 has a flight land portion 14, which perfectly engages a thread bottom portion 13 of the screw 11, and a groove portion 16 which engages a flight thread portion 15 of the screw 11. Therefore the raw material resin is fed from the thread bottom portion 13 to the groove portion 16 and carried forward. The groove portion 16 is substantially full of the resin fed from the thread bottom portion 13 and feeds the resin forward. Unlike conventional screws, the volume of the groove portion is not large, there is no gap nor back flow, the flight thread portion 15 in the groove portion 16 functions as a resin against back flow, and heating of the resin due to back flow is prevented. |
