Abstract An improved injection molding machine is described wherein the so-called ''''wasteless'''' process is achieved by insulating the supply of raw rubber from the mold chamber which is heated during high pressure molding to cure the rubber parts being molded. The present invention is an improvement in the device described in German Offenlegungsschrift No. 2164219 of July 5, 1973, particularly with respect to the details of construction of the insulating plate. The insulating plate in the present invention is preferably made of two pieces intimately bonded by means of a suitable adhesive, with that portion adjacent the mold being formed of a good insulating material and that portion adjacent the supply of rubber being formed of metal to provide adequate strength particularly for withstanding stresses occurring due to breaking of the sprues which extend partially but not completely, through the insulating plate.
IN AN INJECTION MOLDING SYSTEM WHEREIN AN UNCURED ELASTOMER IS INJECTED INTO A MOLD CHAMBER FROM A SUPPLY CHAMBER HAVING A PISTON, THE MOLD CHAMBER IS HEATED TO CURE THE INJECTED ELASTOMER AND THE SUPPLY CHAMBER IS INSULATED FROM THE MOLD CHAMBER BY AN INSULATING PLATE HAVING TFE-LINED FEEDING HOLES THROUGH THE INSULATING PLATE, THE IMPROVEMENT COMPRISING MEANS FOR CAUSING REMOVAL OF UNCURED FLASH MATERIAL BY SAID PISTON WHEREIN THE INSULATING PLATE IS A COMPOSITE PLATE HAVING A METALLIC BACKING MEBER ADJACENT THE ELASTOMER SUPPLY AND AN INSULTING LAYER ADJACENT THE MOLD SURFACE, THE UPPER SURFACE OF THE METALLIC BACKING MEMBER HAVING A TFE COATING, EACH TEF LINED FEEDING HOLE HAVING AN OUTWARDLY FACING CONICAL FEEDING PASSAGE AND AN INWARDLY FACING CONICAL FEEDING PASSAGE, THE APEXES OF THE TWO CONICAL PASSAGES BEING JOINED BY A NARROW CYLINDERICAL PASSAGE AND BEING ALIGNED WITH A SPURE, THE NARROWEST PORTION OF EACH FEEDING PASSAGE BEING ARRANGED AT THE POSITION WHERE THE CURING PROCESS NORMALLY STOPS.
Claim 2
Dependent Claim
162 words
IN AN INJECTION MOLDING SYSTEM WHEREIN AN UNCURED ELASTOMER IS INJECTED INTO A MOLD CHAMBER FROM A SUPPLY CHAMBER HAVING A PISTON, THE MOLD CHAMBER IS HEATED TO CURE THE INJECTED ELASTOMER AND THE SUPPLY CHAMBER IS INSULATED FROM THE MOLD CHAMBER BY AN INSULATING PLATE HAVING TFE-LINED FEEDING HOLES THROUGH THE INSULATING PLATE, THE IMPROVEMENT COMPRISING MEANS FOR CAUSING REMOVAL OF UNCURED FLASH MATERIAL BY SAID PISTON WHEREIN THE INSULATING PLATE IS A COMPOSITE PLATE HAVING A METALLIC BACKING MEBER ADJACENT THE ELASTOMER SUPPLY AND AN INSULTING LAYER ADJACENT THE MOLD SURFACE, THE UPPER SURFACE OF THE METALLIC BACKING MEMBER HAVING A TFE COATING, EACH TEF LINED FEEDING HOLE HAVING AN OUTWARDLY FACING CONICAL FEEDING PASSAGE AND AN INWARDLY FACING CONICAL FEEDING PASSAGE, THE APEXES OF THE TWO CONICAL PASSAGES BEING JOINED BY A NARROW CYLINDERICAL PASSAGE AND BEING ALIGNED WITH A SPURE, THE NARROWEST PORTION OF EACH FEEDING PASSAGE BEING ARRANGED AT THE POSITION WHERE THE CURING PROCESS NORMALLY STOPS.