EP0369568A1

EP0369568A1 - Dispensers for viscous materials

Info

Publication number: EP0369568A1
Application number: EP89303171A
Authority: EP
Inventors: John Patrick Anthony Cox
Original assignee: PC Cox Newbury Ltd
Current assignee: PC Cox Newbury Ltd
Priority date: 1988-11-15
Filing date: 1989-03-30
Publication date: 1990-05-23
Also published as: JPH02144168A; GB8826685D0

Abstract

A dispenser for dispensing viscous material from a cartridge (40) includes a keep (34) having the cartridge and a pneumatic actuator (10) arranged to force pistons in the cartridge to push the material through a dispensing aperture in an outlet boss (44). The keep (34) is pivotably mounted about a transverse axis (36) to rotate between a cocked position for use and an uncocked position in which the cartridge (40) can be loaded in the keep (34). The axis of rotation of the keep is misaligned with respect to the axis of the pistons in the cartridge in order to urge the keep into the cocked position when a dispensing force is applied.

Description

This invention relates to a dispenser for dispensing viscous materials which may be of a thick liquid or pasty nature.
Commonly, adhesives are supplied as a viscous liquid in a plastics cartridge. The cartridge comprises a charge of the adhesive in a tube which has a discharge nozzle at one end and a piston acting within the tube at the other. In many instances the adhesive is supplied as a plurality, usually a pair, of separate substances which are mixed to react and form the adhesive at or near the discharge nozzle. In this case the cartridge can comprise an appropriate number of tubes formed side by side or concentrically. When the discharge pistons are pushed into the tubes the materials are discharged into a common pipe where they are mixed to react before leaving the nozzle.
Particularly in the case of a multi-tube arrangement, the force required to dispense the viscous materials has been found to be uncomfortable, and sometimes impracticable, when relying on manual force. Thus, pneumatic dispensers have been developed. The pneumatic actuator is operated by a trigger which causes a plunger to engage each discharge piston and force the materials from the tube.
While the use of a pneumatic actuator has overcome the problem of applying sufficient force to the discharge pistons, it has been found that the forces applied are often in excess of those with which a standard manual dispenser and cartridge arrangement, adapted for the pneumatic actuator, can cope. Typically, a double barrel cartridge is formed from plastics material with a pair of small flanges extending perpendicularly with respect to the direction of the dispensing force. The flanges are used to engage complementary channels in the dispenser to mount the tubes before the actuating device. The flanges were not designed to cope with the forces associated with a pneumatic actuator and it has been found that these can become dislodged from their channels, rendering the device inoperable. Furthermore, if the materials are particularly viscous the pneumatic force has been found to be enough to cause the cartridge to expand circumferentially and allow the material to seep past the discharge pistons.
Clearly, it is desirable to be able to use standard cartridge shapes without the risk of failure or dislocation of the cartridge in the process.
It is an object of the present invention to provide a dispenser for a viscous material which is both simple to load with a conventional cartridge of viscous material and also reliable in operation.
According to the present invention there is provided a dispenser for dispensing a viscous material from a cartridge having a dispensing aperture at one end, the dispenser comprising: a keep, adapted to house at least part of the cartridge; and actuating means, arranged to apply a material dispensing force to the cartridge; the keep being movably mounted with respect to the actuating means to move between an uncocked position, in which the cartridge is insertable within the keep, and a cocked position, in which the held cartridge is operably aligned with the actuating means.
Preferably, the keep comprises an end wall past which a discharge nozzle of the cartridge can project, the end wall being arranged to restrain movement of the cartridge in the direction of the dispensing force. To this effect it is desirable that the end wall be part of a housing having an internal wall which is of substantially the same sectional dimensions as the section through the cartridge.
Preferably, the keep is pivotable between the cocked and uncocked positions. In this case, it is desirable that the keep pivots about an axis perpendicular to the direction of the dispensing force.
It is preferable that the actuating means comprise a piston head or piston heads, the or each piston head engaging a discharge piston mounted within a corresponding cartridge. In this case, it is preferable that the pivot axis does not intersect the discharge piston axis. It is further desirable that the mis-alignment between the pivot axis and the discharge piston axis is such that the dispensing force tends to urge the keep into the cocked position.
A specific embodiment of the present invention will now be described by way of example with reference to the accompanying drawings in which:

FIGURE 1 is a side view of a dispenser according to the present invention;
FIGURE 2 is a front end view of the dispenser in Figure 1;
FIGURES 3a) and b) are views of a piston assembly forming part of the dispenser shown in Figures 1 and 2; and
FIGURE 4 is a fragmentary section of the right hand end of the dispenser as seen in FIGURE 1, showing the main dump and regulating valves.

Referring to the drawings, a double-barrel dispenser for mixing and dispensing two separate viscous materials comprises a pneumatic cylinder 10, having a barrel 12 containing a pneumatic piston 14. The piston 14 carries two piston rods 16, whose axes intersect a common diameter of the piston 14 and are at equal distances from the axis of the piston 14. Each piston rod 16 is terminated in an actuating piston head 17.
A central rod 16A is also attached to the piston 14. The rod 16A extends parallel to the piston rods 16 but above the center of the piston 14. The rod 16A is terminated in a head portion 17A which is of a smaller diameter than the heads 17. The piston rods 16 pass through closely fitting apertures in a front wall 18 of the cylinder 10, which apertures thus provide piston rod bearings. In which will be preferred to as a retracted position, the actuating piston heads 17 and head 17A are at their extreme extent of travel towards the right-hand side, as depicted in Figure 1. In this position they are received in complementary recesses in the wall 18 so that they are substantially flush with it.
The cylinder 10 is mounted on the top of a grip 20 by means of a collar 22. Self-tapping screws 24 are received in the wall of the cylinder 10 through holes in the collar 22. To hold the cylinder 10 in place, the collar 22 is bolted to the grip 20 by means of bolts 26, which pass through holes in flanges 28, which extend from a stock portion 30 formed on a forward end of the collar 22, down either side of the grip 20.
The stock 30 is also formed with a bracket comprising a pair of upwardly extending arms 32 and 33 to either side of the actuating piston heads 17.
A keep 34 is pivotably mounted between the arms 32 and 33 by means of studs 36. Each stud extends from each of the arms 32, 33 into an adjacent protrusion 38 formed on the outside of the keep 34. The common axis of the studs 36 is above the axis of the piston rods 16 and cylinder 10.
The keep 34 consists of a pair of partially defined parallel tubular bores, merged with one another along an innermost region, to define a generally "Figure 8" section channel in which a double-barrel cartridge 40 of materials to be dispensed can be inserted as a closely fitting item. The end of the keep 34 remote from the stock 30 is formed with an aperture 42 through which an outlet boss 44 of the loaded double-barrel cartridge projects.
In front of the grip 20 is a pivotably mounted trigger 48 which is used to actuate a control valve which regulates the passage of actuating air from an air supply (not shown) which is connected to a threaded intake 50 in the base of the grip 20. An outlet of the control valve is connected through a flexible line 52, to the rear of the pneumatic cylinder 10.
The flexible line 52 leads through an inlet to regulator and dump valves. The dump valve 56 contains a flexible disc 58. When the trigger 48 is pulled, compressed air is passed through the flexible line 52 and moves the disc 58 to the left as seen in Figure 4. Compressed air can then travel around the edges of the disc 58 through notches 60 in the valve body 62 into the interior of the barrel 12 so that pressure is applied to the rear face of the piston 14. On release of the trigger 48 the pressure in the barrel 12 moves the disc 58 to the right as seen in Figure 4, thus opening a large outlet port (not shown) which opens through an adjacent end wall 62 and provides for rapid decompression (dumping) of the pneumatic cylinder 10.
The cartridge 40 comprises a pair of separate bores defined within the same Figure 8 section plastics moulding 54 and a dispensing piston (not shown) in each bore which is used to push the viscous material toward the boss 44. The rear piston-end of the cartridge 40 is formed with a pair of straight flanges (not shown) which face in the direction of the axis of the bores. When the cartridge is inserted in the keep 34 these flanges rest in complementary recesses in the keep 34.
The cartridge is delivered with a cap screwed to the boss 44 and the two bores filled with the two parts of the material to be dispensed. The cap is unscrewed from the boss 44 and replaced by a nozzle.
To load the cartridge 40, the heads 17 and 17A are removed to their fully retracted positions so that they are substantially flush with the front wall 18. The keep 34 is then swung about its pivot studs 36 into an uncocked position in which the end of the keep 34 normally nearest the cylinder 10 is exposed so that the cartidge 40 can be inserted. The cartridge 40 is inserted so that the nozzle on the boss 44 projects through the aperture 42 and the front face thereof is braced against the inner surface of an end wall of the keep 34. With the cartidge inserted, the keep 34 is swung into the cocked position in which the piston end of the loaded cartidge swings past the front wall 18 to lie in line with the piston heads 17.
To dispense the viscous material, the trigger is squeezed to permit air from the supply connected to the threaded intake 50 to act on the face of the pneumatic piston 14 and thus urge the piston heads 17 out of the plane of the front wall 18 and into engagement with the cartridge pistons. In this manner, the material is urged out of the nozzle 44 to be controllably dispensed as each of the piston heads 17, extending into its respective bore, pushes a cartridge piston. As stated above, the cartridge is a close fit within the bores. This will effectively enhance the resistance of the cartridge to distortion in both the axial and circumferential directions as, in use, the cartridge will become axially and circumferentially braced against the inner surface of the keep 34. As the piston heads 17 progress into the cartridge 40 the head portion 17A on the rod 16A advances along the clevis of the Figure 8, providing an indication of the amount of material dispensed/remaining. As the axis of the studs 36 about which the keep 34 pivots is above the centre of the piston rods 16, the keep is urged to rotate clockwise, as depicted in Figure 1, to maintain it in the cocked position.
Once the material in the cartridge 40 is fully dispensed, or it is required to change cartridges before then, a force can conveniently be applied to the head portion 17A to force the piston heads 17 back to their fully retracted position.
While the dispenser has been described in relation to a double-barrel cartridge, it will be apparent to the skilled person that the invention is also applicable to any number of barrels in a cartridge, or separate cartridges, providing that the actuating means are adapted accordingly.
Furthermore, while the keep has been described as being pivotable about an axis perpendicular to the axis of the cartridge bores it could equally well be that the keep is movable out of the path of the piston heads about another axis, such as one parallel to the cartridge axis, so that the keep is effectively rolled between positions. Also, although the dispenser is specifically described as having a pneumatic actuator it is to be understood that the dispenser could be provided with other actuating means to equal effect.
The invention provides a restraint for housing a cartridge against which the dispensing force can be exerted without having to rely on the inherent rigidity of the material from which the cartridge is formed. By housing the cartridge the keep provides a simple manner in which the cartridge or cartridges can be loaded simply and reliably. Alignment of the cartridge with the actuating piston heads is thus dictated by the predefined movement of the keep between limits about its pivot.

Claims

1. A dispenser for dispensing a viscous material from a cartridge (40) having a dispensing aperture at one end, the dispenser comprising; a keep (34), adapted to house at least part of the cartridge (40); and actuating means (10), arranged to apply a material dispensing force to the cartridge; characterised in that the keep (34) is movably mounted with respect to the actuating means (10) to move between an uncocked position, in which the cartridge (40) is insertable within the keep (34), and a cocked position, in which the held cartridge (40) is operably aligned with the actuating means (10).

2. A dispenser as claimed in claim 1, wherein the keep (34) comprises an end wall which is arranged to restrain movement of the cartridge (40) in the direction of the dispensing force.

3. A dispenser as claimed in claim 2, wherein the end wall is provided with an aperture (42) through which a discharge nozzle (44) of the inserted cartridge projects.

4. A dispenser as claimed in claim 2 or 3, wherein the end wall is part of a housing (34) having an internal surface which is of substantially the same internal dimensions as the corresponding external dimensions of the inserted cartridge (40).

5. A dispenser as claimed in any of the preceding claims, wherein the keep (34) is pivotable between the cocked and uncocked positions.

6. A dispenser as claimed in claim 5, wherein the keep (34) is pivotable about an axis (36) perpendicular to the direction of the dispensing force.

7. A dispenser as claimed in any of the preceding claims, wherein the actuating means (10) comprise a piston head or heads (17), the or each piston head being arranged to apply the dispensing force to a discharge piston mounted within a corresponding cartridge (40).

8. A dispenser as claimed in claim 7 when dependent on claim 6, wherein the pivot axis (36) is mis-aligned with respect to the axis of the discharge piston, such that the dispensing force urges the keep into the cocked position.