DE20319464U1 - Plunger for cartridge for holding and pressing out of paste substances has on outer side of plunger wall at least one elastic encompassing blade of plastic orientated at angle outwards in relation to end wall of plunger - Google Patents

Abstract

The plunger (10) for a cartridge for holding and pressing out of paste substances has on the outer side (15) of the plunger wall (14) at least one elastic encompassing blade (16) of plastic which is orientated at an angle outwards in relation to the end wall (12) of the plunger and lies with pretensioning on the inner wall of the container which houses the plunger. The blade on side facing away from the plunger wall has at least one protrusion. An independent claim is included for a cartridge for holding and pressing out paste substances and which is equipped with the proposed plunger.

Description

The invention relates to a piston according to the generic term of claim 1 and a cartridge for storage and squeezing of pasty Substances.

Cartridges of the type mentioned Be kind for the most diverse pasty substances to be sprayed out. Far are common z. B. cartridges for acrylic or silicone, which in Civil engineering can be used to seal joints. Such cartridges are filled and sealed in automatic devices. in this connection the warmed up Substance about a fill pipe through the open end of the cylindrical container of the cartridge into the cylindrical container filled. After that, the open end of the cylindrical container with one, especially pot-shaped, Piston closed. The piston is here, with its front wall ahead, inserted into the cartridge by the device using a plunger. However, there are some problems with this:

Residual air between the filling substance and the piston has the consequence, on the one hand, that it is later processed the filling substance earlier or later from the then open spray opening the cartridge, the cannula, emerges, causing the flow of the pasty Substance is interrupted when the joint filling is sprayed out is called a quick one and continuous joint filling not possible anymore the cannula again after the interruption due to air leakage must be applied which not only delays the workflow, but a smooth, pleasant course the joint filling difficult. The other contains Residual air also contains water, namely in the form of water vapor. Some substances to be ejected, e.g. As silicone, react under the influence of moisture, they harden. The bigger the included, compressed amount of residual air, the larger the proportion of pasty filling substance, that hardens inside the cartridge and thus becomes unusable. As a result, the residual air must be as far as possible be removed from the cartridge.

In the storage and transport condition of the filled The cartridge must On the one hand, seal the piston well so that the trapped substance is prevented from exiting. On the other hand, the piston also has to move so namely slidable in the axial direction within the cartridge, with that later Squeezing the pasty Substance still acceptable powers suffice. Consequently, the piston after filling the cartridge can be moved within a certain range of forces.

Furthermore, the piston may already do not sit too loosely when inserting, because then an impermissible amount will occur pasty Substance past its wall from the cartridge, which is not only to loss of material, but from soiling of the cartridge leads.

However, if the piston is too tight, will - how already executed above - when closing the filled cartridge behind the filled Substance includes a more or less large amount of residual air.

The piston is too tight also leads to that he do not shift sufficiently towards the filled substance can if it subsequently cools down and shrinks, the enclosed volume decreases accordingly. The consequence of the shrinking is then that the container bulges. so Deformed cartridges are practically unsalable because they have a potential Buyer of the The impression arises that the Cartridge a long time ago Time filled has been and the pasty Substance is no longer usable, at least in part. On the other hand such a deformation of the cartridge is disadvantageous because it a later Eject a shift to the cross-section normally round piston significantly hindered and a loss of pasty substance to lead can.

In addition, z. B. when storing the filled Cartridge z. B. by temperature changes an enlargement of the Diameter of the container surrender, the stronger as an increase in the diameter of the Piston. This leaves the sealing effect the piston and air can enter the container and with the pasty Substance come into contact, which causes the pasty substance to harden to lead can.

Due to chemicals in the pasty substance can also swell the piston material, which leads to an enlargement of the Diameter of the piston leads. This allows there are sharp edges on the inner wall of the container and for longer storage the filled Cartridge leads to corrosion stress cracks, that is to say rupture of the cartridge container.

The invention is based on the object for one preferably Small amount of residual air when inserting a piston into a cartridge and at the same time good axial mobility of the used To worry about the piston.

According to the invention, this task is performed by generic piston solved by that on the outside the wall of the piston at least one circumferential elastic lamella is made of plastic, the end wall of the piston essentially oblique outward is directed and bears against the inner wall of the container with pre-tension, and the lamella on its side facing away from the wall of the piston has at least one projection.

The piston can be a rear more open, that is cup-shaped as well as a piston closed at the rear. Besides, can axially offset at least one further projection can be provided. In particular can axially offset several projections all around equidistant be provided.

With essentially angled outward Slats should z. B. also include slats that are not straight, but z. B. arcuate run.

conveniently, the lamella is designed in such a way that when the piston is inserted at least temporarily a circumferential pocket open to the bottom of the container between the end area of the lamella and the inner wall of the container. This allows that on insertion of the piston first of all the residual air clears a path laterally past the piston to the outside can. Because it arises inside the container overpressure when inserting the piston, which leads to that the Air takes the path of least resistance and in your pocket flows and therefore temporarily the lamella lifts off the inner wall of the container and flows outwards. Parallel this becomes the pasty Substance in the area between the wall of the piston and the lamella pressed So that the pasty Substance finally ensures that the Slat again and even stronger than before to the outside is pressed so that in Sectional view is at least punctually sealed and none pasty Substance can penetrate to the side past the piston.

It can also be provided that the free end the slat ends in a point from which to that of the wall of the side facing away from the piston a surface that at least Before inserting the piston away from the end wall of the piston directed obliquely outwards is. This area serves as the inflow surface for the residual air at the beginning of the piston insertion for lifting the lamella from the inner wall of the container.

According to a particular embodiment of the Invention can be provided that the projections are circumferentially equidistant are trained.

It can also be provided that the lamella on its side facing away from the wall of the piston relative to a baseline has at least one return. Such one Can return to enlarge the the area to which the residual air flows at the beginning of the insertion of the piston and thus for faster or further lifting of the slat from the Serve inside the container.

According to another special one embodiment The invention can provide that in the root area of the lamella At least two spaced slots are provided all around.

In particular, can be provided be that the Slits essentially transverse to the direction of rotation of the lamella extend. Through the slots at the beginning of the insertion of the Pistons the residual air more easily from the interior of the container Outside can reach. Of course have to the slots should be so fine that little or no pasty substance with stepping out.

It can also be provided that the wall of the Piston has at least one circumferential sealing lip.

Furthermore, it can be provided that the wall of the piston has a free edge and the free edge radially over the outside the wall protrudes sealing lip. This will, if necessary The sealing effect of the piston is further increased.

It can be provided that the sealing lip forms a slope or an arc towards the inside of the wall.

Furthermore, it can be provided that at the outside the wall of the piston at least one closed and radially protruding sealing edge is formed and the outer diameter the sealing lip is slightly larger than the outside diameter the sealing edge.

Are advantageously on the outside of the Wall of the piston circumferentially at least two axially extending Ribs formed. This serves to reinforce the wall of the piston.

Finally, it can be provided that the piston has an oval cross section in the area of the lamella.

Other possible aspects are that the piston Injection molded from a thermoplastic is that the piston is made of HD-PE plastic is injection molded that the Pistons made of LD-PE plastic is injection molded and that the Piston made of PA plastic is injection molded.

The invention is surprising Understanding that through the provision of a lamella in the manner specified in claim 1 the residual air at least to a much greater extent than before from inside the cartridge is removed and at the same time a well axially movable Piston is provided. Delivers after inserting the piston the prestressed lamella provides a good sealing effect even when deformed and widening the container the cartridge by self-expansion and with it the pasty substance squeeze significantly better than before and also from the inner wall of the container wipe off. The lamella therefore has a ventilation and lock function while a simple sealing lip only a locking (sealing) function having. This results in further application advantages such as higher working pressure and thus much faster spraying.

Furthermore, the sealing and Squeezing without residues on the inner wall of the container is also much better ensured if the piston is already before pressing or during Squeezing out somewhat obliquely to the longitudinal axis of the container the cartridge has placed, which often occurs in practice, because guns tend to fatigue quickly, causing bends arise and the squeeze plate is no longer parallel to the piston rear.

Other features and advantages of Invention result from the claims and the following Description in which several embodiments based on the schematic drawings are explained in detail. It shows:

1 a schematic vertical sectional view through the center of a piston for a cartridge to illustrate the basic structure;

2 the top of 1 on an enlarged scale when inserting the piston into the open end of a cylindrical container of a cartridge;

3 a vertical sectional view through the center of a piston for a cartridge according to a first particular embodiment of the invention;

4 the top of 3 on an enlarged scale when inserting the piston into the open end of a cylindrical container of a cartridge;

5 the piston of 4 at a later stage during deployment;

6 the piston of 5 at a later stage during deployment;

7 the piston of 6 at a later stage during deployment;

8th the piston of 7 at a later stage during deployment;

9 the top of 1 on an enlarged scale when squeezing pasty substance from the now open spray opening of the cartridge;

10 the top of 1 on an enlarged scale when pressing pasty mass compared to the pressure of 9 higher pressure;

11 the top of 1 on an enlarged scale when squeezing pasty mass with compared to that of 10 higher pressure;

12 a vertical sectional view through the center of a piston for a cartridge according to a second embodiment of the invention;

13 a vertical sectional view through the center of a piston for a cartridge according to a third embodiment of the invention;

14 a side view of the wall of the piston of 13 ;

15 Examples of lamella designs;

16 a vertical sectional view of a cartridge with a piston in different stages;

17 a perspective view of a piston according to a fourth embodiment of the invention obliquely from above and detailed view;

18 a vertical sectional view through the center of a piston for a cartridge according to a fifth embodiment of the invention, only half being shown due to the rotationally symmetrical design;

19 the detail X of 18 ; and

20 a side view of the piston of 18 partly in the cut.

The in 1 shown pistons 10 made of plastic is pot-like and has an end wall 12 as well as a closed wall 14 on. On the outside 15 the Wall 14 of the piston 10 is a circumferential elastic slat 16 made of plastic, leading to the front wall 12 of the piston 10 is directed obliquely outwards. On its free edge 18 points the piston 10 one radially over the outside 15 the Wall 14 protruding sealing lip 20 on. To reinforce the front wall 12 are in this inner reinforcement ribs 22 molded.

How clearer it is from 2 results in, the free end of the lamella ends 16 in a spike 24 , from the to the from the wall 14 of the piston 10 opposite side an area 26 emanating from the bulkhead 14 of the piston 10 is directed outwards. When inserting the piston 10 by pushing it into the open end 28 of the cylindrical container 30 the cartridge lays down the lamella 26 under tension on the inner wall 32 of the container 30 because it is through the slat 16 resulting outer diameter larger than the inner diameter of the container 30 while, of course, the outside diameter of the wall 14 less than the inside diameter of the container 30 is. In the 2 on the left is the state before and on the right the state during the initial sliding of the piston 10 in the container 30 shown. It is easy to see that between the surface 26 and the inner wall 32 a circumferential, to the bottom (not shown) of the container 30 open pocket 34 is formed.

The in the 3 The embodiment shown differs from that in FIGS 1 and 2 embodiment shown in that the lamella 16 is designed differently. The slat 16 points like the slat 16 of 1 a peak 24 on, on the on the of the wall 14 of the piston 10 opposite side an area 26 emanating from the bulkhead 12 of the piston 10 is directed obliquely outwards. To the surface 26 there is a return relative to a baseline shown in dashed lines 36 on. The recess serves to enlarge the inflow area for the residual air, as shown in the following 4 to 6 is shown, and leads at the same time in a sectional view to a projection 37 which, however, does not run closed, but is interrupted and thus results in equidistant projections (knobs); whereby air channels are formed between the projections for venting during insertion.

In the 4 is the piston above 10 just like in 2 left before inserting into the open end 28 a container 30 a cartridge and in 4 shown below at a later stage. Because the slat 16 a larger diameter than the inside diameter of the container 30 describes, it lies under tension on the inner wall 32 of the container 30 , but first of all on average in Principle essentially selective in the area of the surface 26 on.

How from the 5 results from pushing the piston 10 in the open end 28 an overpressure that leads to residual air in the container 30 according to the arrow on the surface 26 hits and the slat 16 from the inner wall 32 of the container lifts up, creating an annular gap 38 arises through which residual air can escape to the outside.

6 shows this at a later stage, when the pasty substance is already there 40 the slat 16 approaches.

In 7 the residual air has escaped and the pasty substance spreads 40 mainly between the outside 15 of the piston and the lamella 16 out so that the slat 16 back to the inner wall 32 of the container, which in the present case is punctiform in section. As a result, the piston seals well.

In the 8th is then the state after inserting the piston, e.g. B. the storage condition shown in which the container 30 already slightly deformed, i.e. in the area of the lamella 16 has expanded something. However, this has no effect on the seal, as the lamella 16 spreads independently due to the preload and adapts to the diameter.

In 9 the state is now shown when the piston 10 is pressurized from the left to at least a portion of the pasty substance 40 from the container 30 to squeeze right. For this purpose, of course, is the bottom (not shown) of the container 30 have been opened accordingly. When pressed, a counter pressure arises, which is part of the pasty substance 40 left between the outside 15 of the piston and the lamella 16 suppressed. This leads to a further spreading of the lamella 16 and thus also an expansion of the container 30 in the area of the slat. The piston 10 however, still seals.

In the 10 and 11 the pressure is increased even further. This leads to the lamella 16 is spread even further. In the 10 lies the slat 16 in sectional view at two points 42 and 44 on the inner wall 32 of the container 30 on. In 11 but only on one point 46 , Nevertheless, the piston seals by means of the lamella 16 still starting. The slat 16 therefore also allows you to work faster at higher working pressures.

The Indian 12 shown pistons 10 differs from that in the 3 to 11 shown piston only in that in the direction of squeezing in front of the lamella 16 another slat 48 is provided which is similar to the slat 16 is aligned and is intended for deflecting the residual air and separating residual air and pasty mass (scraper effect). In addition, there is an additional sealing lip 50 intended.

The in the 13 and 14 shown embodiment of a piston 10 differs from that in the 3 to 11 shown in that in the root area 57 the slat 16 circumferentially spaced slots 54 are provided, which extend substantially transversely to the direction of rotation of the slat. Furthermore are on the outside 15 of the piston 10 circumferentially spaced, axially extending ribs 56 to reinforce the wall 14 of the piston.

In the 15 are possible cross-sectional shapes of a slat 16 shown. All of the embodiments shown have a tip 24 on.

16 shows the in 15 Embodiment shown as P_8 in use in a container 30 a cartridge. The piston is in the position shown with Pos._1 10 just been used. It can be clearly seen that in section view at point 58 is sealed. In the state not inserted into the cartridge, the piston has an oval outline in the radial plane at the latter position, which deviates only slightly from a circular outline, but is sufficient to allow residual air to escape from the cartridge at the beginning of the insertion.

In position Pos._2 something pasty substance (not shown) is being squeezed out. This creates a back pressure on the lamella 16 so that it spreads and the container 30 expands. Nevertheless, the piston seals 10 off, this time over an area 60 ,

In position Pos_3, some pasty substance (not shown) is also squeezed out, but the piston is located 10 in a certain inclination. However, this has no effect on the sealing function of the piston 10 , because the prestressed lamella 16 spreads outwards and thus, such as. B. shown in positions Pos_3_0 and Pos_3_U. Even if different areas of the slat above and below 16 on the inner wall 32 of the container 30 the piston seals 10 still starting.

The 17 should serve to give an impression of the circumferentially equidistant projections (knobs) 37 to obtain. In the present example there are twenty four protrusions 37 arranged around the circumference, only a few are marked.

The one in the 18 to 20 shown pistons 10 has three sealing lips 20 . 50 and 62 on. How to look in particular 19 results, the slat points 16 on their off the wall 14 of the piston 10 opposite side circumferential projections 37 only one of which can be seen in the sectional view. Said advantage 37 is almost rectangular in sectional view, the short side of the rectangle, ie the height h, is approximately 0.1 mm.

Finally shows 20 the circumferentially equidistant projections 37 , only a few of which are marked.

The in the description above, in the drawings and in the claims disclosed features of Invention can both individually and in any combination for the realization of the invention in its various embodiments.

Claims (14)

Piston ( 10 ) for a cartridge for storing and squeezing pasty substances ( 40 ) which is a cylindrical container ( 30 ) made of plastic, which is closed at one end with a bottom and at the other end ( 28 ) is open, the piston ( 10 ) is elastic and made of plastic and slidable in the container with one to the bottom of the container ( 30 ) end wall ( 12 ) and a closed wall ( 14 ) is arranged, characterized in that on the outside ( 15 ) the Wall ( 14 ) of the piston ( 10 ) at least one circumferential elastic slat ( 16 ) is made of plastic, which to the front wall ( 12 ) of the piston ( 10 ) is directed essentially obliquely outwards and with prestress on the inner wall ( 32 ) of the container ( 30 ) and the lamella ( 16 ) on her off the wall ( 14 ) of the piston ( 10 ) facing away from at least one projection. Piston ( 10 ) according to claim 1, characterized in that the lamella ( 16 ) is designed so that when the piston is inserted ( 10 ) at least temporarily a circumferential, to the bottom of the container ( 30 ) open pocket ( 34 ) between the end area of the slat ( 16 ) and the inner wall ( 32 ) of the container ( 30 ) results. Piston ( 10 ) according to claim 1 or 2, characterized in that the free end ( 28 ) of the slat ( 16 ) in a tip ( 24 ) ends, from the one to the one from the wall ( 14 ) of the piston ( 10 ) facing away from a surface ( 26 ) which at least before the piston is inserted ( 10 ) from the front wall ( 12 ) of the piston ( 10 ) is directed obliquely outwards. Piston ( 10 ) according to claim 4, characterized in that the projections are circumferentially equidistant. Piston ( 10 ) according to one of the preceding claims, characterized in that the lamella ( 16 ) on her off the wall ( 14 ) of the piston ( 10 ) opposite side relative to a baseline at least one circumferential recess ( 36 ) having. Piston ( 10 ) according to one of the preceding claims, characterized in that in the root area ( 52 ) of the slat ( 16 ) circumferentially at least two spaced slots ( 54 ) are provided. Piston ( 10 ) according to claim 7, characterized in that the slots ( 54 ) essentially transverse to the direction of rotation of the lamella ( 16 ) extend. Piston ( 10 ) according to one of the preceding claims, characterized in that the wall ( 14 ) of the piston ( 10 ) at least one circumferential sealing lip ( 20 ; 50 ; 62 ) having. Piston ( 10 ) according to one of the preceding claims, characterized in that the wall ( 14 ) of the piston ( 10 ) a free margin ( 18 ) and the free margin ( 18 ) one radially over the outside of the wall ( 14 protruding sealing lip ( 20 ) forms. Piston ( 10 ) according to claim 9, characterized in that the sealing lip ( 20 ) to the inside of the wall ( 14 ) forms a slope or an arc. Piston ( 10 ) according to claim 9 or 10, characterized in that on the outside of the wall ( 14 ) of the piston ( 10 ) at least one closed circumferential and radially projecting sealing edge is formed and the outer diameter of the sealing lip ( 20 ) is slightly larger than the outer diameter of the sealing edge. Piston ( 10 ) according to one of the preceding claims, characterized in that on the outside of the wall ( 14 ) of the piston ( 10 ) all around at least two axially extending ribs ( 56 ) are trained. Piston ( 10 ) according to one of the preceding claims, characterized in that the piston ( 10 ) in the area of the slat ( 16 ) has an oval cross section. Cartridge for storing and squeezing pasty substances ( 40 ) with a piston according to one of the preceding claims.