Apparatus for spraying hot melt adhesives

Claim 2

Apparatus for spraying droplets of thermo­plastic adhesive onto a substrate, comprising: first means for ejecting a stream of molten thermoplastic adhesive from the discharge orifice of a spray nozzle; second means for directing a stream of atomizing air against the exterior of said stream of molten thermoplastic adhesive to break up said stream of molten thermoplastic adhesive into droplets; flow control means associated with said first means and said second means for initiating the flow of said stream of atomizing air prior to initiat­ing the discharge of said stream of molten thermoplas­tic material from said discharge orifice, and for stopping the flow of said stream of atomizing air after terminating the flow of said stream of molten thermoplastic material from said discharge orifice.

Claim 3

The apparatus of claim 1 in which said first means includes a pilot air actuated plunger carried in an adhesive passageway formed in said spray nozzle, said plunger being movable between an open position relative to said discharge orifice of said spray nozzle to permit the passage of adhesive therethrough, and a closed position relative to said discharge orifice to top the passage of adhesive therethrough.

Claim 4

The apparatus of claim 2 in which said flow control means comprises: first valve means for supplying pilot air to said plunger to move said plunger between said open position and said closed position; second valve means for supplying atomizing air to said second means, said second means directing the atomizing air against said stream of molten thermoplastic adhesive ejected from said spray nozzle; said second valve means being operable to initiate the supply of atomizing air to said second means prior to movement of said plunger to said open position in response to operation of said first valve means, and said second valve means being operable to terminate the supply of atomizing air to said second means subsequent to the movement of said plunger to said closed position in response to operation of said second valve means.

Claim 5

The apparatus of claim 3 in which said first valve means is a plunger control valve which is effective to meter the flow of pilot air therethrough in a first direction to said plunger to slowly move said plunger to said open position, said plunger control valve being effective to permit the unre­stricted flow of pilot air therethrough in an oppo­site, second direction to quickly bleed air from said plunger and permit said plunger to quickly move to said closed position.

Claim 6

The apparatus of claim 3 in which said second valve means comprises: a pilot operated valve communicating with said second means, said pilot operated valve being movable between an open position in which a stream of atomizing air passes therethrough to said second means and a closed position in which the flow of said stream of atomizing air to said second means is terminated; an air control valve connected to said pilot operated valve and to a source of pilot air, said air control valve being effective to permit the unre­stricted flow of pilot air therethrough in a first direction to said pilot operated valve to quickly move said pilot operated valve to said open position, said air control valve being effective to meter the flow of air therethrough in an opposite, second direction to slowly bleed pilot air from said pilot operated valve and permit said pilot operated valve to slowly move to said closed position.

Claim 7

Apparatus for spraying droplets of thermo­plastic material onto a substrate, comprising: an applicator head comprising: (i) an applicator body; (ii) a spray nozzle mounted to said applicator body, said spray nozzle being formed with an atomizing air passageway and an adhesive passageway having an outlet orifice; (iii) a plunger carried in said adhesive passageway of said nozzle, said plunger being movable between an open position relative to said outlet orifice of said adhesive discharge pas­sageway to permit the passage of a stream of thermoplastic adhesive therethrough, and a closed position to stop the flow of thermoplastic adhesive through said outlet orifice; (iv) pilot air operated, air supply valve means connected to a source of atomizing air and to said atomizing air passageway in said nozzle for opening and closing the flow of atomizing air to said nozzle; support means for mounting said applicator head and for supplying pilot air and molten thermo­plastic adhesive thereto, comprising: (i) air control valve means for controlling the flow of pilot air to said air supply valve means to open and close said air supply valve means; (ii) plunger control valve means for con­trolling the flow of pilot air to said plunger to move said plunger to said open position and to allow said plunger to return to said closed position; (iii) means for continuously supplying adhesive to said spray nozzle.

Claim 8

Apparatus for spraying droplets of thermo­plastic material onto a substrate, comprising: an applicator head comprising: (i) an applicator body; (ii) a spray nozzle mounted to said applicator body, said spray nozzle being formed with an atomizing air passageway and an adhesive passageway having an outlet orifice; (iii) a plunger carried in said adhesive passageway of said nozzle, said plunger being movable between an open position relative to said outlet orifice of said adhesive discharge pas­sageway to permit the passage of a stream of thermoplastic adhesive therethrough, and a closed position to stop the flow of thermoplastic adhesive through said outlet orifice; (iv) pilot air operated, air supply valve means connected to a source of atomizing air and to said atomizing air passageway in said nozzle for opening and closing the flow of atomizing air to said nozzle; support means for mounting said applicator head and for supplying pilot air and molten thermo­plastic adhesive thereto, comprising: (i) air control valve means for controlling the flow of pilot air to said air supply valve means to open and close said air supply valve means; (ii) plunger control valve means for con­trolling the flow of pilot air to said plunger to move said plunger to said open position and to allow said plunger to return to said closed position; (iii) means for continuously supplying adhesive to said spray nozzle.

Claim 9

The apparatus of claim 6 in which said support means comprises a hand-held spray gun having means for manually operating said air control valve means and said plunger control valve means.

Claim 10

The apparatus of claim 6 in which said support means comprises a manifold adapted to mount at least one of said applicator heads, said manifold being formed with a first internal passageway carrying molten thermoplastic adhesive communicating with said nozzle, a second internal passageway carrying pilot air communicating with said plunger and a third internal passageway carrying pilot air communicating with said air supply valve means.