WO1999026865A1

WO1999026865A1 - Cartouche for pasty material

Info

Publication number: WO1999026865A1
Application number: PCT/EP1998/007187
Authority: WO
Inventors: Johannes Kelders
Original assignee: Henkel Kommanditgesellschaft Auf Aktien
Priority date: 1997-11-20
Filing date: 1998-11-11
Publication date: 1999-06-03
Also published as: NL1007591C2

Abstract

The invention relates to a cartouche having a cartouche body (15) in which a displaceable piston (1) is arranged, whereby the piston (1) has a circumferential wall (3) with an outer circumferential sealing lip (11) and an elastic facing wall (2) which is convex toward the inner side of the piston and is deformable in the direction toward the outer side of the piston. At least one first deformable projection (6) is formed on the inner side of the facing wall (2) of the piston (1). Said projection has a stiffness such that the projection deforms when pressure is applied before the convex facing wall (2) reaches its flat state. The cartouche can be used in cartouche guns with any pressure plate such that the convex facing surface of the piston is not permitted to be pressed in the opposite convex position during use.

Description

Cartridge for pasty masses

The invention relates to a cartridge for pasty masses, with a cartridge body in which a displaceable piston is arranged, the piston having a peripheral wall with an outer circumferential sealing lip and an elastic end wall curved towards the inside of the piston, which is deformable in the direction of the outside of the piston.

Such a cartridge is known from DE 42 29 588 C2.

It is known to paste pasty masses, for. B. joint sealants, adhesives and the like, in cartridges made of plastic or other materials. The cartridges generally consist of a cylindrical cartridge body in which a piston is slidably arranged. At the front end of the cartridge body there is an outlet opening through which the pasty mass is pressed out when the plunger is pushed forward. For this purpose, a so-called cartridge gun is used, which has a piston rod with a pressure plate attached to it. When an operating lever is pressed manually against a handle firmly attached to the housing, the pressure plate presses against the inside of the end wall of the piston and thereby pushes the piston forward. A locking device is provided so that the pressure plate does not move backwards when the operating lever is released. Pneumatic cartridge guns which advance the piston with compressed air are also known.

A known problem when using cartridges of this type is the so-called after-running of the pasty mass. When work is interrupted, the pasty mass continues to run out of the cartridge for a short time, even when the piston is no longer under pressure. The cause is in the internal pressure in the cartridge, which has been built up by the movement of the piston in the pasty mass. The piston rod of the cartridge gun, which cannot be moved backwards due to the locking device, or the residual pressure of the compressed air in a pneumatic cartridge gun generally prevent the piston from moving backwards and the paste-like mass from being able to relax in this way. Therefore, the pressure built up inside the cartridge only decreases when the pasty mass flows out of the outflow opening. The run-on can only be reduced if the locking device is released manually so that the piston rod moves backwards or if the remaining compressed air is discharged through another opening. With this reduction in the compressive force acting on the piston, however, the piston moves back slowly and not far enough to completely prevent the run-on, since the friction between the peripheral wall of the piston and the inside of the cartridge body allows the piston to move backwards quickly enough long distance prevented. The running of the pasty mass not only leads to a loss of the often high-quality mass, but also to dirt on the workpiece to be treated. Removing the spilled mass is also difficult and time consuming in many cases.

A cartridge is known from DE 42 29 588 C2 in which this disadvantage is avoided. For this purpose, a cartridge plunger is provided with an elastic end wall curved towards the inside of the plunger, which is flattened out during each extrusion process and then regresses inwards. Following the extrusion process, a suction is created in this way, which pulls the pasty mass back, so that the mass does not run on the outlet opening.

From US 4 030 643 a cartridge with a piston is also known, which has a flexible end wall. The front wall has a protruding provide the mandrel with which the remaining contents can be pressed out of an almost completely empty cartridge through the outlet opening. This piston shows no wiping or sealing lips on the outside of its peripheral wall.

If there is no pressure on the inside of the end wall of the piston according to DE 42 29 588 C2, the sealing lip that runs around the outside of the peripheral wall rests with moderate pressure on the inside of the cartridge body. The seal in this relaxed state of the plunger is sufficient to prevent air from entering the cartridge body. The penetration of air must be prevented as a rule, since many pasty masses harden under the influence of air or change in another way disadvantageously. If, on the other hand, the pressure plate or the compressed air of a cartridge gun presses against the inside of the end wall of the piston, the end wall is pressed into a flatter position and the sealing lip is pressed more strongly against the inside of the cartridge body. The sealing effect of the sealing lip is therefore significantly increased during the pressing process.

When pressing out, however, it must be prevented in any case that the end wall of the piston bulges further beyond the flat state, since in this case the sealing effect of the sealing lip in turn deteriorates considerably. In the cartridge according to DE 42 29 588 C2, it is therefore necessary that the pressure plate of the cartridge gun extends practically over the entire surface of the end wall, so that the end wall can only deform into the flat position and not beyond. If, however, cartridge guns are used which have a pressure plate with a significantly smaller area, the latter can press the end wall of the piston beyond the flat position into the arched position on the other side with the disadvantages already mentioned.

The invention is therefore based on the object of developing a cartridge of the type mentioned at the outset which permits the use of cartridge pistols permitted with any pressure plates, without the end face of the piston being able to be pressed beyond the flat state into the opposite curved position during use.

This object is achieved according to the invention in the cartridge of the type mentioned at the outset in that at least one first deformable projection is formed on the inside of the end wall of the piston and has such a rigidity that it deforms when pressure is applied before the curved end wall becomes flat Has reached state.

In this way, the pressure force exerted by the pressure plate of the cartridge gun on the end wall of the piston is limited and prevents the end wall from bulging toward the inside of the cartridge.

For a particularly uniform distribution of the force exerted by the pressure plate of the cartridge pistol, it is advantageous if the deformable projection is designed as a partially weakened, in particular cylindrical, wall that is coaxial with the peripheral wall of the piston. The deformability of this wall is achieved through the weakening.

The partially weakened wall preferably has recesses running from the upper edge of the wall essentially in the direction of the longitudinal axis of the piston or obliquely thereto.

To limit the deformation of the first projection, for example the cylindrical wall with recesses, it is advantageous if the first projection is weakened only in an area which is arranged at a distance from the inside of the end wall of the piston. In the area directly adjacent to the end wall, the first projection is not weakened, so that this area serves as a stop for the pressure telephoning of the cartridge gun, if one such high force is applied by the pressure plate that the weakened area of the first projection is completely deformed.

The stop for the pressure plate of the cartridge gun when the weakened area of the first projection is completely deformed can also be provided in a different and particularly advantageous manner in that at least one further projection is arranged on the inside of the end wall of the piston, which projection is substantially stiffer than the first projection formed and in particular is arranged radially further outside than the first projection. The further projection can therefore not be deformed with a compressive force which is sufficient to completely deform the weakened area of the first projection. The arrangement of the further projection radially further outward than the first projection ensures that even when a particularly high compressive force is applied to this further projection, the end face of the piston cannot be pressed beyond the flat state into the oppositely curved state.

For a particularly good seal between the outside of the peripheral wall of the piston and the inside of the cartridge body, it is advantageous if the outer circumferential sealing lip has an acute-angled wiping edge.

After the pasty mass has been filled into the cartridge body, it is closed by inserting the piston into the open end of the cartridge body. It is important that the air present between the piston and the pasty mass is removed. To facilitate this process, at least one further stop on the inside of the end wall of the piston is proposed in a further advantageous embodiment, the further stop being arranged, in particular, radially further inward than the first projection. A stamp can engage this stop in order to press the piston inwards into the cartridge body. Through the Position of the further stop further closer to the longitudinal axis of the piston leads to the pressure of the plunger acting on the stop causing the end wall to fold over into the opposite curved state. The sealing lip is drawn in radially somewhat, so that the air present between the piston and the pasty mass can escape past the peripheral wall of the piston to the outside. When the plunger has advanced so far that all air has escaped from the cartridge body, the plunger is withdrawn. The end wall jumps back from the oppositely curved position to the normal state, and the piston pulls even further forward into the cartridge body due to the suction effect.

Two exemplary embodiments of the invention are described in more detail below with reference to drawings. Show it

FIG. 1 shows a longitudinal section through a cartridge piston according to a first exemplary embodiment according to the invention,

2 shows a longitudinal section along the line II-II in Figure 3 by a

Cartridge piston according to a second embodiment of the invention,

Figure 3 is a view of the piston of Figure 2 in the direction of arrow III in

Figure 2,

FIG. 4 shows a top view of the piston according to FIGS. 2 and 3 in the direction of arrow IV in FIG. 2,

Figure 5 is an enlarged detail of the peripheral wall of the piston according to the

Figures 1 and 2 according to the arrow V in Figures 1 and 2 and 6 shows a longitudinal section through a cartridge with a piston according to FIGS. 2 to 5.

In all drawings, the same reference symbols have the same meaning and are therefore only explained once, if appropriate.

The cup-shaped piston 1 shown in FIG. 1 for a cartridge for pasty masses has an end wall 2 which extends over the inner cross section of the associated cartridge body and a peripheral wall 3 which adjoins the edge of the end wall 2 and is essentially perpendicular to the end wall 2. The end wall 2 is light arched inwards so that the outside of the end wall 2 forms a cavity 5 with its edge 4. The end wall 2 is relatively thin-walled and therefore elastically flexible. The end wall 2 and the peripheral wall 3 of the cup-shaped piston 1 comprise an interior 13 into which the pressure plate of a piston rod of a conventional cartridge gun can be inserted in order to press the piston 1 of the cartridge body 15 (FIG. 6) forward and in this way the cartridge to empty.

The stiffness of the elastically flexible, inwardly curved end wall 2 is chosen so that at a normal operating pressure on the piston 1 through the piston rod and the pressure plate of the cartridge gun, the end face 2 bends slightly in the pressure direction, so that the end wall 2 has a flatter position than in assumes an unloaded idle state. The flatter position is represented by the dashed line 2 '. In this way, the cavity 5 delimited by the end wall 2 and the edge 4 is reduced, and the cavity 5 'is obtained. If the pressure force on the inside of the end wall 2 now disappears, the end wall 2 ″ quickly and completely returns to the starting position (end wall 2) due to its elasticity, and the cavity 5 ′ increases again the internal pressure within the cartridge body, which was built up when the end wall 2 was pressed, is reduced again, the pasty mass expanding in the cartridge. The mass does not run on, i.e. the mass emerges from the cartridge without exerting pressure on the piston. As an additional effect, the pasty mass is even sucked back into the cartridge by the end wall 2 moving back.

This enables the pasty mass to be dosed very precisely, there is no loss of the pasty mass and there are no impurities. Because the reduction of the internal pressure inside the cartridge is caused by the resilience of the end face 2, no additional devices for reducing the internal pressure on the cartridge gun are required, so that the cartridge with the piston according to the invention can be used even in the simplest cartridge guns.

Since the end wall 2, which is arched inward in the relaxed state, becomes flatter under pressure, the adjacent area of the peripheral wall 3 is pressed outwards. The seal between the peripheral wall 3 and in particular between the sealing lip 11 formed there and the inside of the cartridge body is considerably improved, so that when the piston 1 is advanced in the cartridge body it is ensured that the entire pasty mass is pushed forward by the piston 1 and no portion this mass between the piston 1 and the wall of the cartridge body can reach the outside. In addition, it is ensured that no air can pass between the peripheral wall 3 and the cartridge body into the interior of the cartridge and mix with the pasty mass, especially when the cartridge is used with a pneumatically operated cartridge gun. In order to be able to precisely adjust the movement of the flexible end wall 2 when an compressive force acts, the piston is equipped according to the invention with a first projection 6 which is attached to the inside of the end wall 2 and which has the shape of a cylindrical wall in the example according to FIG. The wall is weakened in places, namely by V-shaped recesses 7 in the wall (FIG. 1) or by reducing the wall thickness in places (weakening 14 of the wall 6 in FIG. 3). The wall 6 is dimensioned such that it is relatively easy to deform and is practically completely deformed before the end wall 2 has reached the completely flat end position. In this way it is avoided that the end wall 2 is brought into a bulging position by a possibly excessive pressure, so that the sealing lip 11 moves radially inwards again and a gap is formed between the piston 1 and the inside of the cartridge body.

Concentric around the cylindrical wall 6 are further segment-shaped projections 9, which serve as stops (FIG. 3), which do not project as far as the wall 6 from the end wall 2 (FIGS. 1 and 2) and therefore also more rigid and less deformable than that Wall 6 are. The wall 6 and the stops 9 are connected to one another by radially extending ribs which have a bevelled outer edge (FIGS. 1 and 2) and thus center the pressure plate of the cartridge gun, which generally has an axially raised edge which cooperates with these beveled edges . The ratio between the height of the stops 9 above the end wall 2 and the height of the cylindrical wall 6 is chosen so that if the pressure on the wall 6 is unusually strong, it deforms and the pressure plate of the cartridge gun rests against the stops 9 before the end wall 2 is pushed out beyond the completely flat end position. Such a strong pressure force occurs, for example, when the piston 1 has reached the end position in the cartridge body without the user being aware of this. Since the stops 9 are very close to the edge 4 of the end wall 2 are arranged, this very large compressive force does not cause severe deformation of the end wall 2, and a curvature of the end wall 2 beyond the flat end position is avoided.

When pressure is exerted on the underside of the cylindrical wall 6, the cutouts 7 provided in the embodiment according to FIG. 1 become smaller, since the distances between the opposite edges of each cutout are reduced when the wall 6 is compressed. In the case of the design of the piston according to FIGS. 2 and 4, the weakenings 14 of the wall 6 bend outwards in the radial direction and the wall 6 assumes an inwardly curved shape.

A hollow mandrel 12 protrudes from the outer surface of the end wall 2 of the piston 1 according to FIG. 2, which is located inside the outlet opening 19 of the cartridge (FIG. 6) when the piston 1 has reached the end wall 17 of the cartridge body 15. When the cartridge is almost completely empty, the remnants of the pasty mass are pressed out of the outlet opening 19 with the mandrel 12.

The peripheral wall 3 of the piston 1 has, on its outside, known circumferential sealing projections 10 (FIGS. 1 and 2). In addition, according to both exemplary embodiments, the piston according to the invention has the sealing lip 11 already mentioned on the peripheral wall 3 at the level of the end wall 2. The sealing lip 11 preferably has an acute-angled cross section. This arrangement of the sealing lip 11 causes the sealing lip 11 to be pressed outwards in the case of a flattened end wall 2 due to the pressure exerted, as shown in FIG. 5 on an enlarged scale and for the sake of clarity in an exaggerated manner with dashed lines. The seal between the peripheral wall 3 and the inner wall 16 of the cartridge body 15 (FIG. 6) is considerably improved in this way. Concentric to the cylindrical wall 6, on the inside of the end wall 2 there is also a further stop 22 projecting relatively slightly from the end wall 2 in the form of a likewise cylindrical wall (FIGS. 1 to 3). When the cartridge body 15 is filled, the further stop 22 serves as a stop for a stamp which presses the piston 1 into the cartridge body 15. As shown in Figure 6, the cartridge body 15 has a cylindrical shell 16 which is delimited on one side by an end wall 17 in which the outlet opening 19 is located. The other end 21 of the cartridge body 15 is open. At the outlet opening 19, an outlet nozzle 20 is fastened, which is closed during the manufacture of the cartridge and is cut off at the tip by the user before the cartridge is used for the first time. The jacket 16 and the end wall 17 thus delimit a chamber 18 which is open on one side and is filled with a viscous or pasty mass such as adhesive, joint sealant or the like.

When filling the cartridge, the mass is filled in at the other end 21 before the piston 1 is inserted into the cartridge body 15. When the cartridge is completely filled with the mass, the piston 1 is inserted into the open end 21 of the cartridge body 15 and pressed into the cartridge body 15 in the direction P with the aid of a stamp. This ensures that the cartridge body 15 is completely filled and any air present therein is pressed out. The stamp engages, as has already been explained, on the further stop 22 and exerts such a strong compressive force that the end wall 2 bulges outwards beyond the flat position. This creates an annular gap between the sealing lip 11 of the piston 1 and the inner wall 16 of the cartridge body. The air that may be present between the end wall 2 and the pasty mass is pressed outwards through this gap. The elastically flexible end wall 2 of the piston 1 therefore enables the cartridge body 15 to be appropriately filled arched position of the end wall 2 is limited by the edges of the recesses 7, the adjacent, opposite edges of the recesses 7 approaching each other when arching the end wall 2 and finally abut one another when the end wall has reached the desired outwardly curved position.

In summary, the following advantages are achieved in particular with the cartridge according to the invention. Follow-up is avoided under all circumstances. A very good seal between the piston and the inner wall of the cartridge body is guaranteed. The cartridge can be filled by machine in a particularly simple and economical way.

Reference number list

piston

Front wall 'dashed line

Peripheral wall

Edge, 5 'cavity first protrusion, cylindrical wall

Recesses

Ribs further projection, stop 0 sealing projection 1 sealing lip 2 mandrel 3 interior

Weakening of the wall 6 5 cartridge body 6 inner wall, jacket 7 end wall 8 chamber 9 outlet opening 0 outlet nozzle 1 other end 2 further stop

Claims

claims

1. Cartridge for pasty masses, with a cartridge body (15) in which a displaceable piston (1) is arranged, the piston (1) having a peripheral wall (3) with an outer circumferential sealing lip (11) and a bulging toward the inside of the piston has an elastic end wall (2) which can be deformed in the direction of the outside of the piston, characterized in that on the inside of the end wall (2) of the piston (1) at least one first deformable projection (6) is formed, which has such a stiffness, that it deforms when pressure is applied before the curved end wall (2) has reached its flat state.

2. Cartridge according to claim 1, characterized in that the deformable projection is designed as a weakened in places, in particular cylindrical and with the peripheral wall (3) of the piston (1) coaxial, wall (6).

3. Cartridge according to the preceding claim, characterized in that the partially weakened wall (6) from the upper edge of the wall substantially in the direction of the longitudinal axis of the piston (1) or obliquely extending recesses (7).

4. Cartridge according to one of the preceding claims, characterized in that O 99/26865

that the first projection (6) is weakened only in an area which is arranged at a distance from the inside of the end wall (2) of the piston (1).

5. Cartridge according to one of the preceding claims, characterized in that on the inside of the end wall (2) of the piston (1) at least one further projection (9) is arranged, which is substantially stiffer than the first projection (6) and in particular radially is arranged further outside than the first projection (6).

6. Cartridge according to one of the preceding claims, characterized in that the outer circumferential sealing lip (11) has an acute-angled scraping edge.

7. Cartridge according to one of the preceding claims, characterized by at least one further stop (22) on the inside of the end wall (2) of the piston (1), the further stop (22) in particular radially further inward than the first projection (6) is arranged.