| 摘要 |
<p>The invention relates to a single nozzle injection molding system in which the nozzle is reciprocated longitudinally to valve gate the flow of melt to the cavity. The nozzle has a pointed tip which seats in the gate in the forward closed position and is retracted to the open position. The nozzle is secured against rotation, and an inner collar is secured to it. This inner collar threadably engages a surrounding outer collar which is free to rotate, but secured longitudinally. A pneumatic piston is connected to the outer collar to rotate it through a predetermined angle. Thus, when the outer collar is rotated in one direction, the inner collar and nozzle are driven to the forward closed position, and when the outer collar is rotated in the opposite direction the inner collar and nozzle are retracted to the open position.</p> |
