Hot melt cartridge adhesive gun

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

• a handle;
• a gun housing of thermally insulative, non-stick material mounted on the handle and defining a chamber having an opening in a wall thereof for insertion of said cartridge into the chamber, said chamber being sufficiently cool to retain said adhesive cartridge in substantially solid form;
• a nozzle means having a discharge orifice for molten adhesive;
• check valve means communicating with nozzle means;
• a heater block coupled to said nozzle means and disposed at the forward end of said chamber and including a face having a plurality of projections confronting said chamber and into engagement with which said adhesive cartridge is urged for melting, said projections defining a plurality of communicating channels;
• at least one electrical heating element disposed in said block for heating said block to an operating temperature sufficient to melt said adhesive in engagement with said projections;
• a thermostat mounted on said block for maintaining the temperature of said block substantially constant;
• a reservoir in said block for maintaining a quantity of molten adhesive therein;
• a first passage in said block coupling said communicating channels to said reservoir;
• a second passage in said block coupling said reservoir at a level above the level of said first passage and said nozzle means;
• a plunger disposed for slidable movement in said chamber through a predetermined distance for urging said cartridge into engagement with said projections;
• a connecting rod connected to said plunger and extending through the rear wall of said chamber and rearwardly of said gun;
• a gripping plate having an opening therethrough said opening having a bell-mouthed forward end and a sharp edged rearward end riding on said rod outside said rear wall of said chamber;
• a compression spring surrounding said rod and disposed between said gripping plate and said rear wall of said chamber;
• an actuating trigger supported by said handle and engaging said gripping plate and operative throughout its rearward motion to urge said gripping plate against said compression spring thereby causing said gripping plate to engage directly with said plunger rod against the action of said compression spring to propel said plunger rod and plunger forwardly throughout the rearward motion of the trigger thereby providing pressure to deform a partially melted portion of said cartridge against the walls of said chamber to provide a seal against backflow of molten adhesive and to force molten adhesive through said first passage and said reservoir and to open said check valve means and to force molten adhesive through said second passages, and out through said nozzle;
• a retraction lever having an opening therethrough said opening having a bell-mouthed forward end and a sharp edged rearward end riding on said connecting rod rearwardly of said gun;
• means pivotally connecting one end of said retraction lever to said handle;
• spring means coupled between said retraction lever and said handle and cooperating with said lever to permit retraction of said plunger by a predetermined amount when said actuating trigger is released, thereby relieving the pressure of said plunger on said cartridge so as to allow the check valve means to close and arrest the flow of liquid adhesive at substantially the same time that the actuating trigger is released;
• means for disengaging said retraction lever;
• means rearwardly of said gun for retracting said plunger to permit reloading of the gun by insertion of a cartridge into the opening in the wall of said chamber.

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

• a handle;
• a gun housing of thermally insulative, non-stick material mounted on the handle and defining a chamber having an opening in a wall thereof for insertion of said cartridge into the chamber, said chamber being sufficiently cool to retain said adhesive cartridge in substantially solid form;
• nozzle means having a discharge orifice for molten adhesive and check valve means for selective opening of said orifice;
• a heater block coupled to said nozzle means and disposed at the forward end of said chamber and including a face having a plurality of projections confronting said chamber and into engagement with which said adhesive cartridge is urged for melting, said projections defining a plurality of communicating channels;
• at least one electrical heating element disposed in said block for heating said block to an operating temperature sufficient to melt said adhesive in engagement with said projections;
• a thermostat mounted on said block for maintaining the temperature of said block within a predetermined temperature range;
• a reservoir in said block for maintaining a quantity of molten adhesive therein;
• a first passage in said block coupling said communicating channels to said reservoir;
• a second passage in said block coupling said reservoir at a level above the level of said first passage and said nozzle means;
• a plunger disposed for slidable movement in said chamber through a predetermined distance for urging said cartridge into engagement with said projections;
• a connecting rod connected to said plunger and extending through the rear wall of said chamber and rearwardly of said gun;
• first and second gripping blocks disposed on respective opposite portions of said connecting rod and each having a gripping surface cooperative with a cooperating surface of said rod;
• first and second links pivotally connected to said gripping blocks to permit gripping motion of the gripping surfaces of said blocks;
• a cam surface on one of said gripping blocks;
• a compression spring surrounding said rod and disposed between said gripping blocks and said rear wall of said chamber;
• an actuating trigger supported by said handle and having a portion engaging said cam surface and operative throughout its rearward motion to urge said gripping blocks against said compression spring and to produce movement of said gripping surfaces into large area gripping contact with the confronting surfaces of said plunger rod to propel said plunger rod and plunger forwardly throughout the rearward motion of the trigger thereby providing pressure to deform a partially melted portion of said cartridge against the walls of said chamber to provide a seal against backflow of molten adhesive and to force molten adhesive through said first passage and said reservoir and to open said check valve means and to force molten adhesive through said second passages, and out through said nozzle;
• a retraction lever having an opening therethrough said opening having a bell-mouthed forward end and a sharp edged rearward end riding on said connecting rod rearwardly of said gun;
• means pivotally connecting one end of said retraction lever to said handle;
• spring means coupled between said retraction lever and said handle and cooperative with said lever to permit retraction of said plunger by a predetermined amount when said actuating trigger is released, thereby relieving the pressure of said plunger on said cartridge so as to allow the check valve means to close and arrest the flow of liquid adhesive at substantially the same time that the actuating trigger is released;
• means rearwardly of said gun for retracting said plunger to permit reloading of the gun by insertion of a cartridge into the opening in the wall of said chamber.

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

• a handle;
• a gun housing of thermally insulative non-stick material mounted in the handle and defining a chamber having an opening in a wall thereof for insertion of said cartridge, said chamber being sufficiently cool to retain said adhesive cartridge in substantially solid form;
• adhesive cartridge driving means disposed for slidable movement in said chamber through a predetermined distance and including a plunger rod extending through the rear wall of said chamber and rearwardly of said gun;
• infinitely resolvable ratchet means supported by said handle and in operative engagement with said driving means and including:
• a first gripping block having a substantially planar gripping surface disposed in confronting relation to a first surface of said plunger rod;
• a second gripping block disposed on an opposite side of said plunger rod from said first gripping block and having;
• a curved gripping surface in confronting relation to a second surface of said plunger rod, and
• a planar surface confronting said second surface of said plunger rod and a curved gripping surface contiguous with said planar surface and disposed with respect to a pivot pin connected to said link to provide eccentric rotational movement about said pivot pin upon actuation of said trigger to cause large area gripping contact with the confronting surfaces of said plunger rod;
• first and second links each disposed on a respective side of said gripping blocks and pivotally connected thereto to permit gripping motion of the gripping surfaces of said blocks;
• a cam surface provided on said second gripping block and cooperative with said actuating trigger to produce, upon actuation of said trigger, movement of the gripping surfaces of said blocks into large area gripping contact with the confronting surfaces of said plunger rod, the gripping force of said blocks on said plunger rod being related to the degree of actuating force applied to said trigger;
• an actuating trigger supported by said handle and coupled to said ratchet means and operative throughout its rearward travel to urge said driving means forward against said cartridge;
• retraction means disposed about said rod extending rearwardly of said gun and operative upon release of said actuating trigger to permit retraction of said driving means by a predetermined amount;
• nozzle means having a discharge orifice for molten adhesive;
• valve means communicating with the nozzle means and operative to open the nozzle orifice when the trigger is actuated;
• a heater block coupled to said nozzle means and disposed at the forward end of said chamber and including;
• a face confronting said chamber and into engagement with which the front of said adhesive cartridge is urged for melting;
• at least one electrical heating element disposed in said block for heating said block to an operating temperature sufficient to melt said adhesive in engagement with said face;
• a reservoir in said block for maintaining a quantity of molten adhesive therein;
• a first passage in said block coupling said face to said reservoir;
• and
• a second passage in said block coupling said reservoir at a level above the level of said first passage to said nozzle means;
• whereby when said drive means is urged against said cartridge, pressure is provided to deform a partially melted portion of said cartridge against the walls of said chamber to provide a seal against backflow of molten adhesive and to force molten adhesive through said first passage and said reservoir and to open said valve means to permit flow of molten adhesive through said second passage, and out through said nozzle.