Thermoplastic dispenser

A hot melt adhesive dispensing handgun for translating solid slugs of thermoplastic feedtock material from a solid state to a molten state and for dispensing said feedstock while in the molten state, said handgun comprising

• a supporting body having a handle grip extending downwardly therefrom,
• a barrel mounted within said body, said barrel having a feedstock input end and a discharge end,
• said discharge end of said barrel being in communication with a gun discharge nozzle,
• a valve located within said gun body for controlling flow of molten feedstock from said nozzle,
• a trigger located adjacent said hand grip and operatively connected to said valve,
• a ram movable within said barrel to effect movement of a solid slug of thermoplastic feedstock material from the input end of said barrel toward the discharge end,
• a motor mounted upon said gun body rearwardly of said ram for controlling actuation of said ram,
• a heater located adjacent the discharge end of said barrel for heating said feedstock and converting it from the solid to the molten state,
• said barrel having successive zones defined therein comprising a solid feedstock feed zone, a feedstock softening zone, and a feedstock melt zone, said feedstock melt zone being located adjacent the discharge end of said barrel and in close proximity to said heater, and
• a tubular forming die located interiorly of said barrel, said forming die being at least partially located within said feedstock softening zone of said barrel, said forming die having at least one portion of a lesser diameter than the solid feedstock feed section of said barrel,
• said forming die having a tapered throat located within said softening zone for receiving a solid slug of feedstock material and guiding it into said one portion of said forming die in which said solid slug is sized by said forming die so that surface contact is maintained between said solid slug of feedstock material and said forming die substantially around the periphery of said solid slug of feedstock material, said surface contact being operative as a physical dam to prevent rearward flow of molten feedstock material past said one portion of said forming die.

A dispensing device for translating solid slugs of thermoplastic feedstock material from a solid state to a molten state and for dispensing said feedstock while in the molten state, said dispensing device comprising

• a barrel having an input end and a discharge end,
• a ram movable within said barrel to effect movement of a solid slug of thermoplastic feedstock material from the input end of said barrel toward the discharge end,
• a heater located adjacent the discharge end of said barrel for heating said feedstock and converting it from the solid to the molten state,
• said barrel having successive zones defined therein comprising a solid feedstock feed zone, a feedstock softening zone, and a feedstock melt zone, said feedstock melt zone being located adjacent the discharge end of said barrel and in close proximity to said heater, and
• a sizing constriction located within said feedstock softening zone of said barrel, said sizing constriction being of a lesser inside diameter than the solid feedstock feed section of said barrel,
• said sizing constriction being operative to compress at least a portion of stock material as it passes through said feedstock softening zone of said barrel so as to establish surface contact between said solid slug of feedstock material and said constriction substantially all the way around the periphery of said solid slug of feedstock material, said surface contact then being operative as a seal and physical dam to prevent rearward flow of molten feedstock material past said constriction.