What are mold unscrewing devices?
The drawing represents one type of unscrewing mold. This design can be used for one or more cavities. Additional racks and pinions could be added for more cavities if press size and capacity were big enough. The power to drive the rack can be from an air or hydraulic cylinder, (as shown here) a motor driven gear train, or a rack and pinion gear train driven by the mold and press opening and closing.
Mold Unscrewing Devices Actuation
The closed mold has the rack in its retracted position and the pinion gear forward, so that the threaded core is in its molding position. After molding and cooling, the mold opens completely, parts stay on the ejection mold half. Then the piston is timed to push the rack forward, causing the pinion gears and shafts to rotate counter clockwise. The pinion shaft will screw into the lower thread bushing, while the threaded core on top of the shaft will unscrew out of the part, ejecting it from the mold.
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