Injection molding mechanical double acting valve pin actuator

Mechanism for reciprocally actuating an injection molding valve pin having a tip end and enlarged driven end along its longitudinal axis comprising:

• (a) an elongated valve pin,
• (b) an elongated toothed rack member reciprocable in a plane substantially transverse to the longitudinal axis of the valve pin,
• (c) drive means for reciprocally driving the rack means in said plane according to a predetermined sequence,
• (d) a bushing assembly including a hollow bushing with a threaded outer surface and a flange portion, a collar with an aperture to receive the bushing therethrough and a seat to receive the flange portion therein, and a plate located adjacent the collar to receive the flange portion of the bushing therebetween with fastening means to securely fasten the plate to the collar to frictionally secure the bushing and valve pin to the plate and collar, the bushing assembly being seated in the surrounding fixed member to prevent rotation but allow axial movement of the bushing assembly and valve pin, and
• (e) a hollow rotatable pinion member having a threaded inner surface and a toothed outer surface secured against substantial transverse movement, the valve pin extending through the pinion member with the threaded outer surface of the bushing screwed into the threaded inner surface of the pinion member to position the tip end of the valve tip in a desired position before the valve pin is securely fastened to the bushing assembly, the toothed outer surface of the pinion member engaging the toothed rack member,
• whereby driving the rack member in one direction rotates the pinion member and actuates the valve pin along its longitudinal axis to a closed position, and driving the rack member in the opposite direction rotates the pinion member in the other direction and actuates the valve pin to an open position.