| 摘要 |
<p>This invention relates to improved mechanism for actuating injection molding valve pins. In one embodiment, the mechanism is located between two parallel rows of valve pins located in a common plane with their driven ends adjacent the mechanism. The mechanism includes a central elongated member which is longitudinally reciprocable and two parallel elongated transversely reciprocable side members, each located between the central member and one of the rows of valve pins. Each of the side members is connected to the central member by a number of spaced pairs of pivotally connected pins and the central member is secured against transverse motion, while the side members are secured against longitudinal motion. Therefore, the side members are reciprocated transversely when the central member is reciprocated longitudinally by a hydraulic cylinder. The side members each have outer faces in contact with the driven ends of the valve pins of one of the rows and the outward motion of the side members actuates the valve pins along their longitudinal axis to a closed position in which the tips of the valve pins are seated in their respective gates. When the central member is returned to the open position, the side members are drawn closer together allowing the valve pins to withdraw under the pressure of the melt. In addition to providing a simplified mechanism for actuating the valve pins in unison, this mechanism has the advantage that the link structure causes the valve pins to move through the minimum distance with maximum force as they approach the closed position. In addition, the opposing forces applied by the side members to the central member balance each other out to a considerable extent.</p> |
