Adhesive gun having needle valve nozzle

For use in a hot melt adhesive applicator, a needle valve nozzle assembly comprising:

• a nozzle housing adapted for connection to a chamber containing a quantity of hot melt adhesive;
• a cylindrical nozzle having a discharge orifice at one end and an annular lip at the opposite end and being slidably attached to the discharge end of said housing;
• a cylindrical sleeve surrounding a portion of said nozzle containing said lip and secured to the discharge end of said housing;
• heater means within said housing between the discharge end of said chamber and said nozzle and into engagement with which said adhesive is urged to melt a quantity thereof;
• a passage extending through said nozzle housing and communicating with said chamber for flow of melted adhesive therethrough;
• a stationary needle fixedly mounted at one end to said heater means and extending through said passage into said nozzle with the distal end in sealing engagement with said discharge orifice when said nozzle is in a closed position;
• spring means disposed within an annular space between confronting portions of said nozzle and said sleeve and operative to urge said nozzle inward into a normally closed position with the distal end of said needle in sealing engagement with the discharge orifice of said nozzle;
• an expansible adhesive compartment between inner surfaces of said nozzle and said housing;
• sealing means disposed between relatively sliding surfaces of said nozzle, said housing and said sleeve in positions isolated from the melted adhesive;
• an annular pneumatic chamber formed between said lip and confronting portions of said housing and sleeve;
• and
• a conduit communicating with said pneumatic chamber for applying operating gas thereto from an external source to urge said nozzle into its open position for dispensing of adhesive from said discharge orifice.

A hot melt adhesive gun for use with a cartridge of normally solid thermoplastic adhesive, said gun comprising:

• a housing defining a chamber adapted to contain a cartridge of normally solid thermoplastic adhesive;
• heater means disposed at the discharge end of said chamber and into engagement with which said adhesive cartridge is urged to melt a confronting quantity thereof;
• a reciprocable nozzle disposed at the discharge end of said housing and having a discharge orifice for the discharge of said adhesive;
• a conduit extending from said chamber through said heater means to said nozzle for conducting said adhesive to said nozzle;
• a stationary needle fixedly mounted to said heater means and extending through said conduit and said nozzle means and into said discharge orifice, said needle being in sealing engagement with said discharge orifice when said nozzle is in a closed position;
• biasing means affixed to said nozzle for biasing said nozzle into its closed position;
• pneumatically actuated means for slidably urging said nozzle in a direction outward from said stationary needle into an open position wherein said discharge orifice projects beyond said needle and out of engagement therewith, thereby allowing said adhesive to flow through said discharge orifice from said conduit;
• driving means disposed for sliding movement in said chamber and pneumatically actuable to urge said adhesive cartridge into engagement with said heater;
• trigger means pneumatically coupled to said driving means and to said pneumatically actuable means;
• venting means communicating said driving means and said pneumatically actuable means with the working atmosphere;
• said trigger means being operative upon actuation to apply operating gas to said driving means and to said pneumatically actuable means to urge said adhesive cartridge in said chamber into engagement with said heater means, and to urge said nozzle into its open position;
• said trigger means being operative upon deactuation to discontinue application of operating gas to said driving means and to said pneumatically actuable means and to couple said driving means and said pneumatically actuable means to said venting means, thereby allowing said biasing means to urge said nozzle into its closed position.

For use in a hot melt adhesive applicator, a needle valve nozzle assembly comprising:

• a nozzle housing adapted for connection to a chamber containing a quantity of hot melt adhesive;
• a reciprocable nozzle disposed at the discharge end of said housing and having a discharge orifice at one end for the discharge of adhesive therefrom and a second end facing said nozzle housing;
• a conduit in communication between said chamber and said discharge orifice for conducting said adhesive to said discharge orifice;
• a stationary needle fixedly mounted to said housing and extending through at least a portion of said conduit and into said discharge orifice, said needle being in sealing engagement with said discharge orifice when said nozzle is in a closed position;
• biasing means operative to urge said nozzle into said closed position to prevent flow of adhesive through said discharge orifice;
• pneumatically actuated means disposed adjacent said second end of said nozzle and adapted for urging said nozzle into an open position upon the application of pneumatic pressure thereto, said discharge orifice of said nozzle being spaced from said needle when said nozzle is in an open position;
• actuating means adapted to apply pressurized operating gas to said pneumatically actuated means for opening said nozzle and to discontinue application of pressurized operating gas to said pneumatically actuated means and to vent said pneumatically actuated means to an exterior atmosphere to permit said biasing means to urge said nozzle into its closed position.