Injection molding of liquid thermosetting resins

Abstract

Abstract THE INSTANT APPLICATION DISCLOSES A NOVEL INJECTION MOLD SPRUE AND NOZZLE COMBINATION WHICH EMABLES A TROUBLEFREE INJECTION MOLDING OF QUICK-CURING LIQUIE THERMOSETTING RESINS TO BE ACHIEVED. THE COMBINATION IS CHARACTERIZED BY THE PROVISION OF A MOLD SPRUE WHICH IS IN THE FORM OF A RECESS CONSIDERABLY LARGER THAN THE NOSE OF THE NOZZLE TO BE JUXTAPOSED THERETO AND DEFINES A HIATUS BETWEEN THE DISCHARGE END OF THE NOZZLE BORE AND THE INLET END OF THE MOLD RUNNER SYSTEM, THEREBY CONTRASTING WITH CONVENTIONAL ARRANGEMENTS WHICH ARE CHARACTERIZED BY A FLUSH AND TIGHT NOZZLE TO MOLD FIT TO BRING THE NOZZLE BORE AND THE MOLD RUNNER SYSTEM INTO ABUTTING AND DIRECTLY COMMUNICATING END TO END RELATION. THE DEPTH OF THAT PART OF THE SPRUE WHICH IS NOT OCCUPIED BY THE NOZZLE MUST EXCEED THE DEPTH OF THE RUNNER SYSTEM. THUS, SINCE THE RESIN FILLING THE SPRUE GELS INWARDLY FROM THE WALLS THEREOF, THE INJECTION PRESSURE CAN BE RELEASED AND THE NOZZLE SEPARATED FROM THE MOLD BEFORE THE GELATION OF THE RESIN IN THE SPRUE IS COMPLETED, THEREBY AVOIDING THE POSSIBILITY OF THE RESIN GELLING BACK INTO THE NOZZLE. A CHECK VALVE IS PROVIDED IN THE NOZZLE SYSTEM TO INHIBIT AFTER-DRIBBLE OF RESIN AS WELL AS ASPIRATION OF AIR INTO THE RESIN SUPPLY UPON RELEASE OF THE INJECTION PRESSURE.

Inventors

• 👤 Leon Laufer
• 👤 Steve Noto

Bibliographic Details