Apparatus for dispensing adhesive material

A method of dispensing a solid adhesive block made of hot melting material in a pistonless adhesive dispenser which includes a feed passage the forward end of which has a dispensing outlet, comprising the steps of:

• forming on the adhesive block at least one flange dimensioned for resiliently yielding but fluid-tight sealing engagement with the said feed passage;
• inserting the said block in the feed passage;
• supplying pressurized fluid to the rear end of the adhesive block to advance the adhesive block along the feed passage to the dispensing outlet with the rear end of the adhesive block and said at least one flange acting together as a piston face directly to receive pressurized fluid;
• and
• melting the forward end of the block as it advances along the feed passage, whereby to dispense liquid adhesive from said outlet.

Dispensing apparatus for dispensing adhesive material comprising:

• a. a housing;
• b. a feed passage in the housing adapted to receive adhesive in the form of at least one normally substantially solid but heat-liquefiable block which has seal-forming means adapted to form a fluid-tight yet yieldable seal with the feed passage,
• c. a discharge opening for liquefied adhesive communicating with the feed passage,
• d. coupling means for enabling the feed passage to be connected to a source of pressurized fluid so that in use fluid pressure is applied directly to a said block in the feed passage without the intermediation of a mechanical piston to advance the said block axially along the feed passage towards the discharge opening;
• e. heating means for heating and progressively liquefying a said block of adhesive from its leading end, the solid portion of the said block serving, in use, as a piston for the liquefied portion thereof with said seal-forming means preventing pressurized fluid from coming into contact with said liquefied portion,
• f. actuating means for controlling the flow of pressurized fluid from said source via the coupling means to the feed passage, and
• g. a vent opening communicating with the atmosphere and defined in the wall of the feed passage such that where in use the seal-forming means of the rearmost of said at least one block has been liquefied by heat, further application of heat will result in such fluid rushing through the vent opening to provide an operator with an aural warning and substantially to prevent said fluid from passing through the discharge opening.

Dispensing apparatus for dispensing adhesive material comprising:

• a. a housing;
• b. a feed passage in the housing adapted to receive adhesive in the form of at least one normally substantially solid but heat-liquefiable block which has seal-forming means to form a fluid-tight yet yieldable seal with the wall of the feed passage,
• c. nozzle means for discharging liquefied adhesive and communicating with the forward end of the feed passage,
• d. actuating means adapted normally to prevent any flow of pressurized fluid from a source of such fluid to the feed passage and adapted on actuation to permit such flow;
• e. permanently open fluid flow ducting extending from said actuating means to the feed passage so that in use pressurized fluid flows directly to the rear of a said block in the feed passage without the intermediation of any mechanical means to propel the said block axially along the feed passage towards the discharge opening;
• f. heating means located adjacent the forward end of the feed passage for heating and progressively liquefying a said block of adhesive from its leading end, the solid portion of the said block serving, in use, as a piston for the liquefied portion thereof with said seal-forming means preventing pressurized fluid from coming into contact with said liquefied portion;
• and
• g. a load opening in the feed passage through which said block may be loaded into the feed passage, a cap displaceable to cover and uncover the load opening, a latch for securing the cap in its position covering the load opening, a deformable sealing member, a recess defined between adjacent surfaces of the cap and the edges of the said opening, the recess receiving said sealing member mounted as a loose fit, a fluid inlet opening defined in the feed passage forwardly of the load opening, the arrangement being such that when the cap is closed and latched, introduction of pressurized fluid into the feed passage deforms the sealing member to make a fluid-tight seal between the cap and the said edges.