Two-Cavity Unscrewing Mold for a Glass Fiber Reinforced Polyamide Threaded Plug

Two-Cavity Unscrewing Mold for a Glass-Fiber-Reinforced Polyamide Threaded Plug The threaded plug consists of a top flange with a hexagonal recess in its upper surface. The underside of the flange has a pot-shaped section that encloses the hexagonal recess and to the bottom of which a stop pin is attached. This section is enclosed by an outer ring that carries the threads. In addition, the underside exhibits an annular groove ‘‘O’’ around the outer ring and intended to hold a seal. The annular space between the pot-shaped section and outer ring contains radial ribs. Mold Release of the annular groove and threads is accomplished most easily by unscrewing the molded part from a threaded sleeve. The mold is designed with two cavities. Release of the threads is accomplished on the stationary mold half. The threaded sleeves are located in guide bushings and are driven by the gear and spindle of the unscrewing mechanism. The annular core forms the stop pin and, by means of a tubular extension, the annular space in the plug. A central core pin provides for venting of the stop pin cavity. The hexagonal recess is formed by the core insert , which also encloses an ejector pin . The other ejector pins are used to knock out the sprue and runner. Gating The location of the ejectors and unscrewing mechanism requires that injection takes place into the mold parting line . Each plug has a single submarine gate located at the flange. Mold Temperature Control The mold plates on either side of the parting line have cooling lines encircling the mold inserts. The annular core contains a double-threaded cooling pin. Part Release=Ejection The latch causes the mold to first open at parting line ‘I’. This withdraws the annular core from the underside of the plug and releases the stop pin. This motion is limited by the stop bolt . The opening motion is now interrupted and the unscrewing begins. The threaded sleeve is unscrewed while the hexagonal core insert prevents the molded part from turning. Upon completion of unscrewing, the main parting line ‘II’ opens, shearing off the submarine gates. The molded part is still retained on the core insert; the sprue and runner are held by the undercut in the sprue puller. As the ejector plate moves forward, the ejector pins eject the molded part and the sprue.