EP0396689B1

EP0396689B1 - A sealing arrangement for an adhesive dispenser

Info

Publication number: EP0396689B1
Application number: EP19890911852
Authority: EP
Inventors: Quentin Grant
Original assignee: UNI-CONTINENTAL HOLDINGS Ltd
Current assignee: UNI-CONTINENTAL HOLDINGS Ltd
Priority date: 1988-10-31
Filing date: 1989-10-30
Publication date: 1994-01-19
Anticipated expiration: 2009-10-30
Also published as: GB8825394D0; AU4483089A; EP0396689A1; DE68912575D1; WO1990005096A1

Abstract

A sealing arrangement for an adhesive dispenser comprises a plug (7) for removing the air from a barrel of the dispenser when introduced thereto and a sealing stopper (23) for engagement with the plug (7) which prevents air from being re-introduced into the barrel or the contents of the barrel escaping therefrom as the stopper (23) is moved into engagement with the plug (7).

Description

THIS INVENTION relates to a sealing arrangement for adhesive dispensers and, more particularly, an arrangement for sealing adhesive dispensers without the use of rubber o-rings.
Various products such as adhesives and resins are supplied to the user in a dispenser having a barrel with an open charging end through which the product is introduced into the barrel and a dispensing end provided with a nozzle through which the product is dispensed. It is known to seal such a container by removing air from the barrel of the dispenser in order to keep the adhesive or resin from reacting with the air and becoming unusable.
The sealing is carried out by first inserting a plug into the open end of the barrel of the dispenser after the barrel has been charged with produce, the plug having a rubber o-ring co-operating with the internal wall of the barrel to seal the adhesive within the dispenser from the atmosphere outside the plug. Mechanical pins are then forced between the rubber o-ring of the plug and the internal wall of the barrel. Any air trapped between the adhesive or resin and the plug is bled from around the sides of the rubber o-ring which recovers its full sealing capability once the pins are withdrawn.
It is also known to provide part of the internal wall of the dispenser barrel adjacent its open end with one or more moulded lugs extending axially within the interior barrel. As the plug is pushed into the barrel, the action of forcing the rubber o-ring over the lug or lugs bleeds the air trapped between the product and the plug around the ring and the ring again recovers its sealing capability once it has passed clear of the lug or lugs.
DE-A-2,302,364 which forms the preambles for independent claims 1 and 15, teaches an apparatus for bleeding air from a barrel containing a product by inserting a plug into the barrel, the plug having a hole through which the air is bled. The hole is sealed by a second plug. Grooved portions formed in the second plug allow air trapped between the product and the second plug to escape through the second plug.
The above known methods of sealing dispensers are not suitable where damage may be sustained to the plug or sidewall of the barrel of the dispenser as the plug is inserted. Furthermore, the above methods are unsuitable for use with certain adhesives and resins which react with the rubber o-ring thus rendering the seal unsuitable for use.
A further disadvantage of the above prior art methods is that it is difficult to ascertain when all the air trapped between the adhesives or resin and the sealing plug in the barrel has been removed. With many adhesives or resins it is imperative to remove all the air in order to stop the adhesive or resin from reacting with the air and undergoing an irreversible transformation.
The present invention aims to overcome or at least mitigate the above problems presented by the prior art by providing a sealing arrangement which will not damage the internal wall of the dispenser barrel and does not react with the adhesive or resin within the dispenser.
Accordingly, the invention provides a sealing arrangement for sealing a dispenser having a cylindrical sealing arrangement for sealing a dispenser having a cylindrical barrel with an open charging end through which a flowable product is introduced into the dispenser, which arrangement comprises a plug for inserting into the barrel after introduction of the product and formed with a guide bore communicating with a bleed aperture in the plug through which air trapped between the plug and the product escapes, a stopper engagable in the guide bore of the plug to seal the bleed aperture in the plug, and escape means for allowing air in the guide bore to be discharged, wherein the guide bore and the stopper have co-operating surfaces defining an annular gap which is isolated from the contents of the dispenser and the atmosphere when the stopper is engaged in the guide bore and which traps any escaped product.
A method of sealing a dispenser having a cylindrical barrel with an open charging end through which a flowable product is introduced into the dispenser, comprising the steps of : introducing into the open end of the barrel a sealing plug formed with a guide bore communicating with a bleed aperture through which the air trapped between the plug and the product escapes; engaging a stopper in the guide bore of the plug so that no air is forced back through the plug and the co-operating surfaces of the guide bore and the stopper define an annular gap which is isolated from the contents of the dispenser and the atmosphere and which traps any escaped product; and locking the stopper in engagement with the plug.
In order that the invention may be more readily understood, embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which :

FIGURE 1 is an axial cross-section of a sealing arrangement embodying the present invention inserted in a barrel of a dispenser;
FIGURE 2 is an axial cross-sectional view of the sealing arrangement of Figure 1 in a sealed condition;
FIGURE 3 is an end view of a sealing plug comprising part of the sealing arrangement of Figure 1;
FIGURE 4 is a plan end view of the sealing arrangement of Figure 1 with the sealing plug removed;
FIGURE 5 is a cross-sectional view of the sealing plug of Figure 3;
FIGURE 6 is an axial cross-section of a sealing arrangement according to a second embodiment of the present invention inserted within an open portion of a dispenser;
FIGURE 7 is a cross-sectional view of the sealing arrangement of Figure 6 in a sealing condition;
FIGURE 8 is end view of part of the sealing arrangement of Figure 7;
FIGURE 9 is a cross-sectional view of a modified sealing plug of a sealing arrangement embodying the present invention; and
FIGURE 10 is an axial cross-section of the modified sealing plug of Figure 9 inserted in a sealing arrangement.

Referring firstly to Figures 1 and 2, a cylindrical barrel 1 of a dispenser has an open charging end 3 through which a flowable product, such as an adhesive or resin is introduced into the barrel which has its other or dispensing end provided with a nozzle (not shown) through which the product is dispersed in use of the disperser.
A sealing arrangement, generally indicated at 5, comprises a plug 7 of plastics material which is inserted into the open end 3 of the dispenser 2 after the barrel 1 has been charged with the product to be dispensed. The plug 7 forms a tight fit within the barrel 1 and has a concave leading surface 7A.
The plug 7 has an axially extending peripheral skirt 9 having a slightly concave outer surface 11. A central region of the outer surface 11 of the skirt 9 is provided with one or more (in this case three) radially projecting circular ribs 13.
The plug is formed with a central circular bleed aperture 15 surrounded by an axially extending annular wall 17. The axial length of the wall 17 is approximately half that of the peripheral skirt 9.
A conical portion of the internal surface 19 of the wall 17 flares towards a free end of the wall 17 so as to interconnect the aperture 15 with a portion of the wall 17 having an internal diameter which is greater than the internal diameter of the aperture 15.
The free end of the wall 17 is formed with axial projections in the form of castellations 21 which are shown in phantom in Figures 1 and 2. In the illustrated embodiment of the invention, two casellations are provided and, as shown in Figure 4, the castellations are offset from each other by approximately 180 degrees and extend around the surface of the wall 17 for approximately 90 degrees. The castellations have approximately the same axial length as the wall 17.
A stopper plug, generally indicated at 23 and shown in detail in Figure 5 is provided for sealing the aperture 15 of the plug 7. The stopper is of integral construction.
The sealing plug 23 has a cylindrical main portion 25 which fits tightly within the larger diameter portion of the wall 17. A cylindrical intermediate portion 27 of the plug 23, also being cylindrical in configuration is of smaller diameter than the main portion 25. The main and intermediate portions 25 and 27 of the plug 23 are joined by a substantially radially extending shoulder 29. At its end remote from the shoulder 29, the intermediate portion 27 terminates in an axially extending cylindrical stem portion 33 which has a smaller diameter than the intermediate portion 27 to which it is connected by a topped conical shoulder 31 intended to cooperate with the conically tapered portion of the internal surface 19 of the upstanding wall 17.
The stem portion 33 of the stopper 23 is formed at its free end with a conical head 35 defining with the stem a radially extending annular sealing surface 37 of greater external diameter than the diameter of the aperture 15. The sealing surface 37 is intended to engage the underside of the plug 7 around the aperture 15 when the sealing plug 23 is in place as shown in Figure 2. As can be seen in Figure 2, the circular end surface of the main stopper portion 25 when inserted into the plug 7 is substantially flush with the castellations 21 of the wall 17 and the free end of the skirt 9.
With the stopper 23 inserted in the plug 7, an annular gap 39 is defined between the circumference of the intermediate portion 27 of the stopper 23 and part of the internal circumference 19 of the wall 17. The annular gap 39 is isolated from both the adhesive and the open end of the barrel 1 by sealing engagement between the respective portions of the stoppers 23 and the internal surface 19 of the wall 17.
In use of the sealing arrangement embodying the present invention, the plug 7 is inserted into the open end of the dispenser 2 within which it is desired to seal adhesive or resin already introduced into the barrel. The concave outer surface 11 of the skirt 9 and annular ribs 13 provided thereon ensure that the plug 7 grips the internal wall of the barrel 1 in order to provide an effective seal between the plug 7 and the barrel.
As the plug 7 is inserted into the barrel, air trapped between the reservoir of adhesive or resin and the plug forced out through the aperture 15 in the centre of the plug 7. When all the air trapped above the adhesive is removed from the container, the adhesive begins to enter the aperture 15 and rise within the bore 19.
The plug 7 is inserted further into the container until the adhesive within the bore 19 rises to the level of the flared portion of the bore. The stopper 23 is then inserted into the bore as shown in Figure 1.
As the stopper 23 is inserted into the bore, the adhesive which has risen in the bore is displaced by the head 35 of the stopper 23 and is forced to rise further between the bore 19 and the stopper 23. This causes the air above the adhesive in the bore 19 to be expelled from the bore between the casellations 21. However, before any adhesive can exit the bore in the same way, the head 35 of the stopper engages in the aperture 15 of the plug 7 and prevents further adhesive being drawn into the bore 19. Simultaneously, the main portion 25 of the sealing plug 23 moves into cooperation with the bore 19 as shown in Figure 2, thus effectively isolating the adhesive within the annular gap 39 from the reservoir within the container 1 and the free end of the container.
The radial sealing surface 37 of the head 35 snaps into engagement with the underside of the plug 7 around the aperture 15 and prevents the stopper 23 from being removed from the bore 19.
With the stopper 23 in the position shown in Figure 2, the plug 7 can then be advanced within the barrel 1 in order that the adhesive or resin in the reservoir in the container is delivered through a nozzle connected to the end of the barrel 1 remote from the free end thereof.
It will be appreciated that the stopper 23 could be provided at the foot of a hand plunger wherein the upper portion 25 of a sealing plug 23 would be extended in order to form a handle upon which pressure would be exerted in order to advance the plug 7 within the container and force adhesive from the nozzle end of the container.
In a second embodiment of the present invention, shown in Figure 7 to 9, the wall 17 is extended to approximately the same axial length as the skirt 9. The castellations 21 which allows air to escape from the bore 19 as the sealing plug 23 is inserted into the bore in the first embodiment, are replaced in this second embodiment by one or more channels 41 through the wall 17 such that air in the bore 19 may escape as the stopper 23 is inserted into the bore. When the stopper is in place (as shown in Figure 8) the apertures 41 are completely covered by the main portion 25 of the sealing plug. Thus, as in the previous embodiment, the adhesive trapped in the annular gap 39 is prevented from escaping from the bore 19 by the cooperation of the main portion 25 of the stopper and the wall 17.
The sealing arrangements shown in the illustrated embodiments of the present invention lend themselves to being fabricated from plastics materials for example by a process such as injection moulding or die casting.
In a further embodiment of the present invention shown in Figures 9 and 10, a rubber o-ring 41 acts between the concave outer surface 11 of the plug 7 and the internal wall of the barrel 3. This provides a further seal between the plug 7 and the barrel 3.
In this embodiment the sealing plug 23' is provided with an integral annular base 43 at the end remote from the conical head 35. The annular base 43 has an axially extending peripheral skirt 45 which is received between the peripheral skirt 9 and the annular wall 17 of the plug 7 when the sealing plug 23' is inserted in the bore 19. The skirt 45 snugly engages the wall 17 of the plug 7 but is radially spaced from the skirt 11 so as to leave an air bleed gap 46.
The free ends of the peripheral skirt 45 are formed with axial projections in the form of castellation 47.
In use of the sealing arrangement according to this further embodiment of the present invention, the plug 7 is inserted into the open end of the dispenser 2. The concave outer surface 11 of the skirt 9, the annular ribs 13 and the rubber o-ring 41 ensure that the plug 7 grips the internal wall of the barrel 1 in order to provide an effective seal.
As described with the embodiments of Figures 1 to 8, as the plug 7 is inserted into the barrel, air trapped between the reservoir of adhesive or resin and the plug is forced out through the aperture 15 in the centre of the plug 7. The air trapped above the adhesive escapes between the castellations 21 and 47 through the air bleed gap 46. However, before any adhesive can exit the bore in the same way, the head 35 of the stopper engages in the aperture 15 of the plug 7 and prevents further adhesive being drawn into the bore 19. Simultaneously, the main portion 25 of the sealing plug 23' moves into cooperation with the bore 19, thus effectively isolating the adhesive within the annular gap from the reservoir within the container 1 and the free end of the container.

Claims

A sealing arrangement for sealing a dispenser having a cylindrical barrel (1) with an open charging end (3) through which a flowable product is introduced into the dispenser, which arrangement comprises a plug (7) for inserting into the barrel (1) after introduction of the product and formed with a guide bore (15) communicating with a bleed aperture in the plug (7) through which air trapped between the plug (7) and the product escapes, a stopper (23) engagable in the guide bore (15) of the plug (7) to seal the bleed aperture in the plug (7), and escape means for allowing air in the guide bore (15) to be discharged, characterised in that the guide bore (15) and the stopper (23) have co-operating surfaces defining an annular gap (39) which is isolated from the contents of the dispenser and the atmosphere when the stopper (23) is engaged in the guide bore (15) and which traps any escaped product.
A sealing arrangement according to Claim 1, wherein the plug (7) comprises an axially extending circular wall (17), the internal surface (19) of which defines the guide bore (15).
A sealing arrangement according to Claim 1 or 2, wherein the guide bore (15) has a portion adjacent the bleed aperture which is connected to a portion of the bore of greater diameter by a flared portion of the bore (15).
A sealing arrangement according to any one of Claims 1 to 3, wherein the stopper (23) has a portion (27) of reduced radial width and sealing surfaces are provided axially on each side of the portion (27) of reduced width, which sealing surfaces cooperate with the wall of the bore (15) on each side of the portion (27) of reduced width in order to define the isolated annular gap (39).
A sealing arrangement according to any one of Claims 1 to 4, wherein the stopper (23) is provided with a depending skirt (31) which snugly engages the axially extending circular wall (17) of the plug (7) and defines an air bleed gap (39) with the plug (7).
A sealing arrangement according to any one of Claims 2 to 5, wherein the circular wall (17) is provided with the escape means for allowing air in the bore (15) to be discharged as the stopper (23) is moved into engagement with the plug (7).
A sealing arrangement according to Claim 6, wherein the escape means are in the form of one or more castellations (21) provided on the axial end of the wall (19).
A sealing arrangement according to Claim 6, wherein the escape means are in the form of one or more radially extending channels (41) in the wall (17).
A sealing arrangement according to any one of Claims 1 to 8, wherein means are provided for locking the stopper (23) into engagement with the plug (7).
A sealing arrangement according to Claim 9, wherein the locking means comprises a head (35) of the stopper (23) which protrudes through the aperture (15) in the plug (7), the head (35) being provided with an annular sealing surface (37) which engages the surface of the plug (7) in the bleed aperture and prevents the stopper (23) from being removed from the plug (7).
A sealing arrangement according to any one of Claims 1 to 10, wherein the plug (7) is further provided with an axially extending peripheral skirt (9) for sealingly-engaging the internal wall of the barrel.
A sealing arrangement according to Claim 11, wherein the outer surface (11) of the axially extending peripheral skirt (9) is concave and is formed with annular ribs (13) in order to improve the sealing engagement of the plug (7) with the internal wall of the barrel (1).
A sealing arrangement according to any one of Claims 1 to 12, wherein the plug (7) has a concave leading surface (7A) for abutting the product in the barrel (1).
A sealing arrangement according to any one of the preceding claims wherein the stopper (23) forms part of a hand plunger which may then be used to advance the sealing arrangement within the barrel (1) to expel the contents from a nozzle connected to a dispensing end of the barrel.
A method of sealing a dispenser having a cylindrical barrel (1) with an open charging end (3) through which a flowable product is introduced into the dispenser, comprising the steps of : introducing into the open end (3) of the barrel (1) a sealing plug (7) formed with a guide bore (15) communicating with a bleed aperture through which the air trapped between the plug (7) and wherein the product escapes; engaging a stopper (23) in the guide bore (15) of the plug (7) so that no air is forced back through the plug (7) and characterised in that the co-operating surfaces of the guide bore (15) and the stopper (23) define an annular gap (39) which is isolated from the contents of the dispenser and the atmosphere and which traps any escaped product; and locking the stopper (23) in engagement with the plug (7).