EP0213073B1 - Device for mixing and applying liquid or pasty substances - Google Patents

Description

The invention relates to a device according to the preamble of patent claims 1 and 6.

Two different types of devices are known for squeezing and metered mixing of liquid or pasty masses from cartridges. In the first type, e.g. B. by EP-A-0 119 847 and DE-A-2 521 392, it is multi-chamber cartridges with integrated ejection piston. In the second type, e.g. B. by DE-A-3 128 611 and FR-A-2 501 080, are devices that are also suitable for the simultaneous pressing of several separate single-chamber cartridges. Here, the pistons are part of the device and not the cartridges.

The second type has fundamental advantages over the first. In particular, from a wide range of cartridges in terms of content, only those that deliver an optimal mix for the respective application can be selected directly at the site. Squeezing devices of the second type can in principle also be designed for higher squeezing pressures; among others they are therefore also more suitable for more viscous masses.

The invention relates to a device of the second type. The devices of this type, which have become known to date, could not meet higher requirements with regard to accuracy and constancy of the mixing ratio, or only to a certain extent with the acceptance of structural disadvantages, particularly when metered mixing of masses of very different viscosities.

With regard to the coupling of the squeeze-out pistons or piston parts, a construction is known from FR-A 2 501 080 in which the pistons or piston parts are coupled to one another by cross rods connecting the piston rods. With this construction, the large space requirement is particularly troublesome. With full cartridges or pistons located at the rear ends of the cartridges, the piston rods with the cross rods protrude out of the device by a full cartridge length. The device is therefore rather unwieldy.

In contrast, the device known from DE-A-3 128 611 with a jaw coupling in the drive mechanism is already considerably more manageable, although here too the piston rods behind the device are disruptive. The main disadvantage is that the clamping jaws are only effective during the advance of the pistons. Without special additional measures, in particular locking mechanisms, it cannot be ruled out that the pistons will slide back to different degrees during intermittent use, so that they will no longer be at the same level during the next pressing process and the mixing ratio will therefore be disturbed.

When mixing highly viscous and low-viscosity masses, their different flow behavior becomes increasingly noticeable at the beginning and at the end of the extrusion. The highly viscous substance will generally run out with a delay due to "inflation" of the cartridge and compression of air inclusions, in order to continue to flow at the end of the application until the overpressure in the cartridge is reduced again. From EP-A-0 105 181 manually operable valves are provided in the discharge pipes of the device to avoid this disadvantage. Experience has shown, however, that such valves are often not operated, especially during short work breaks.

The stated shortcomings of the prior art are intended to be remedied by the invention. A device is to be created which, in order to avoid mixing errors, has a reliable coupling of the piston arrangement which is also effective during work breaks, and which is characterized by a small space requirement. Furthermore, in order to reduce mixing errors to a minimum, the device should have means which only allow the substances to flow simultaneously. This object is achieved with regard to the coupling of the pistons by the features mentioned in the characterizing part of patent claim 1 and with regard to the inevitable simultaneity of the flow of the substances by the features mentioned in the characterizing part of patent claim 6.

The selected piston arrangement with continuous slots for the cartridge walls and knives as piston coupling means is always effective. Knives or web can be made so narrow that only low frictional forces can be overcome when cutting. Furthermore, piston rods are no longer required to transmit the coupling forces, so that they can be dispensed with entirely in pneumatic or hydraulic operation, for example.

Compared to the clamping jaw coupling of the piston rods known from DE-3 128 611, the direct coupling of the piston parts according to the invention is simpler, more reliable and, moreover, also fully effective when the pistons are retracted. The latter is particularly advantageous if the cartridges are emptied with an interruption, since it is inevitably ensured that all piston parts are always at the same level and that the dosage is always the same at the start of each new squeezing process.

Piston arrangements with knives are known per se in multi-chamber cartridges, but it is not the outer walls of the cartridges (as in the invention) but the intermediate walls that are cut there. In the multi-chamber cartridge known from EP-A-0 119 847, the intermediate wall is even cut out in its entirety (on both side edges) and rolled up behind the piston arrangement or deflected laterally. In addition to the system-related disadvantages (see above), this has a wide range Ren disadvantage of an increased power requirement to overcome the roll-up or deflection resistance.

The mixing errors, which can occur especially when applying differently viscous masses, are essentially reduced to a minimum by the movable arrangement of the cartridges in the housing combined with an opening mechanism. With the aid of this arrangement, a valve which can be actuated by the pressing-out pressure of the pistons can be realized. This makes it possible to open and close the cartridges specifically for the application.

In a particularly advantageous embodiment of the invention, the cartridges or their holder can only be moved into the front end position in the housing against a return spring. In this case, the masses only flow out of the cartridges when the squeezing pressure has overcome the spring force of the opening mechanism. The backward movement of the cartridges at the end of an application proves to be particularly advantageous. It causes suction at the mouth of the device and thus prevents the substances from dripping.

Further preferred embodiments of the invention are the subject of the remaining dependent claims.

• Fig. 1 ein erstes Ausführungsbeispiel in der Ruhestellung im Längsschnitt,
• Fig. 2 ein Detail der Fig. 1 in perspektivischer Darstellung,
• Fig. 3 ein weiteres Detail der Fig. 1 in Explosionsdarstellung im Axialschnitt,
• Fig. 4 das erste Ausführungsbeispiel in der Arbeitsstellung,
• Fig. 5 ein weiteres Detail der Fig. 1 im Axialschnitt,
• Fig. 6 das Detail der Fig. 5 in Aufsicht,
• Fig. 7 ein zweites Ausführungsbeispiel teilweise im Axialschnitt,
• Fig. 8a, 8b ein drittes Ausführungsbeispiel in der Ruheposition (Fig. 8a) und in der Arbeitsposition (Fig. 8b) jeweils im Axialschnitt,
• Fig. 9a ein Detail der Fig. 8a bzw. 8b in einer perspektivischen Explosionsdarstellung,
• Fig. 9b das Detail der Fig. 9a im Axialschnitt,
• Fig. 10 eine Ausschnittsvergrösserung aus der Fig. 8a bzw. 8b,
• Fig. 11 eine Variante des Details der Fig. 9a bzw. 9b in perspektivischer Explosionsdarstellung,
• Fig. 12 ein weiteres Detail der Fig. 8a und 8b in perspektivischer Explosionsdarstellung,
• Fig. 13 das Detail der Fig. 11 zusammengesetzt mit zwei Kartuschen in perspektivischer Darstellung,
• Fig. 14a, 14b ein viertes Ausführungsbeispiel in der Arbeitsposition (Fig. 14a) und in der Ruheposition (Fig. 14b) jeweils im Axialschnitt, und
• Fig. 15 eine perspektivische Explosionsdarstellung des Ausführungsbeispiels der Fig. 14b.

In the following the invention will be explained by the exemplary embodiments shown in the figures; show it

• 1 shows a first embodiment in the rest position in longitudinal section,
• 2 shows a detail of FIG. 1 in perspective,
• 3 shows a further detail of FIG. 1 in an exploded view in axial section,
• 4 the first embodiment in the working position,
• 5 shows a further detail of FIG. 1 in axial section,
• 6 shows the detail of FIG. 5 in supervision,
• 7 is a second embodiment partially in axial section,
• 8a, 8b, a third embodiment in the rest position (Fig. 8a) and in the working position (Fig. 8b) each in axial section,
• 9a shows a detail of FIGS. 8a and 8b in a perspective exploded view,
• 9b shows the detail of Fig. 9a in axial section,
• 10 shows an enlarged detail from FIGS. 8a and 8b,
• 11 shows a variant of the detail of FIGS. 9a and 9b in a perspective exploded view,
• 12 shows a further detail of FIGS. 8a and 8b in a perspective exploded view,
• 13 shows the detail of FIG. 11 assembled with two cartridges in a perspective view,
• 14a, 14b a fourth embodiment in the working position (FIG. 14a) and in the rest position (FIG. 14b) in each case in axial section, and
• 15 is an exploded perspective view of the embodiment of FIG. 14b.

The housing of the device shown in FIG. 1 consists of a support tube 1, a front cover 11, which is fixed by a union nut 10 that can be screwed onto the support tube 1, and a rear screw-on closure cap 9. A cartridge 2 is located inside the support tube 1 , which is double-walled. An inner partition 7 defines a cylindrical space in which the one component, for example a resin, is introduced. This cylindrical space is referred to below as the central chamber 3. A cylindrical annular space is formed from the intermediate wall 7 and an outer wall 35 of the cartridge 2, which is referred to below as the annular chamber 4. The other component, for example a hardener, is introduced into this annular chamber 4. The two chambers 3 and 4 are delimited at the front by the front wall 33 of the cartridge 2. At the rear end, the central chamber 3 is equipped with a round piston 5, and the annular chamber 4 with an annular piston 6. The pistons 5 and 6 have sealing lips 8 at their edges. Four blades 19, two of which are visible in FIG. 1, connect the two pistons 5 and 6. Decentrally at the outer edge of the front wall 33 of the cartridge 2, the chambers 3, 4 open into a cartridge opening 13. The intermediate wall 7, which extends into the Cartridge mouth 13 is sufficient, dividing the latter into separate output channels 24 and 25, respectively. A valve piece 14 is pushed into the cartridge mouth 13 and is explained in more detail with reference to FIGS. 2 and 3. This is clamped by means of a union nut 50 on an outlet connection 49 formed by the front cover 11. A mixing nozzle 23 is attached to the mouth of the valve piece 14. The attachment is also carried out by means of the union nut 50. On the front cover 11 there is also a front connecting piece 15 for the inlet of compressed air. The cover 9 screwed onto the rear end of the support tube 1 contains a rear connection piece 20 for compressed air.

Fig. 2 shows a perspective view of the valve piece 14. It is provided with two valve channels 28, 29, which are indicated by dashed lines, the inlet openings of which can still be seen in the figure. The valve piece 14 is provided from the rear with a slot 27 into which the part 12 of the partition 7 located in the cartridge mouth 13 can be pushed. At the rear part of the valve piece 14 there are two sealing lugs 30.

Adjacent to the sealing lugs 30, two valve slots 43 serve to admit the components into the valve channels 28, 29. In the front area there is an annular elevation 51, on the front shoulder of which the valve piece 14 is fastened to the outlet connection 49 by means of the union nut 50 (see in this respect Fig . 1). The mixing nozzle 23 is fastened to the thread 32 by means of the union nut 50 (the latter is also shown in FIG. 1). The front part of the valve piece 14 is closed off by a partition wall 26 which is explained in more detail below.

3 shows in an exploded view how the mixing nozzle 23 can be fastened on the valve piece 14 by means of the union nut 50. In longitudinal section through the valve piece 14, the two valve channels 28, 29 are clearly recognizable. The mixing nozzle 23 is designed at its rear end as an attachment 53, so that a liquid-tight contact is ensured between the valve piece 14 and the mixing nozzle 23. The components to be processed are kept separate when passing through the interior of the attachment 53 through the partition wall 26 of the valve piece 14. A multiplicity of mixing elements are located in a static mixing channel 52 of the mixing nozzle 23. The term "static" means that there are no moving parts.

Fig. 4 shows the relative displacement between the valve piece 14 and the cartridge 2 when it is in the front position. It can be seen that the cartridge mouth 13 opens the valve slots 43 so that the substances in the cartridge chambers 3, 4 can easily get into the valve channels 28 and 29, respectively.

5, the piston assembly 5, 6, 19 is shown from the side. The annular piston 6 is visible on the left, in the middle of the round piston 5. The two pistons 5, 6 are connected by blades 19. Both the annular piston 6 and the round piston 5 have sealing lips 8 at the front edges.

6 shows a top view of the piston assembly. In the middle, the round piston 5 is again visible, which is connected via four blades 19 to the annular piston 6 arranged coaxially around it.

The operation of the device is explained below. By actuating an actuation button or actuation lever, not shown in FIG. 1, a changeover part 22 of a schematically illustrated three-way valve 21 is brought into position 1. As a result, compressed air is conducted into the rear connecting piece 20 and the piston assembly 5, 6, 19 is pushed forward. In a first phase, the cartridge 2 together with the piston assembly 5, 6, 19 is pushed forward until the cartridge front wall 33 comes to a stop on the front cover 11. With the displacement movement of the cartridge 2 to the front, the rear part of the valve piece 14 reaches the interior of the two chambers 3 and 4 from the cartridge opening 13. This cartridge position is shown in a partial view according to FIG. 4.

In a second phase, the piston assembly 5, 6, 19 now also moves relative to the cartridge 2 and is pushed forward in it. This movement is possible because the connecting elements between the pistons 5, 6 are designed as blades 19 and continuously cut the intermediate wall 7 of the cartridge 2. No substance can run out at the interface, since the blades 19 are arranged behind the piston surfaces facing the substances. Since the Patron 2 is only used once anyway, it is of no importance that the partitions are cut after use. Due to the pressure of the piston assembly 5, 6, 19, the substances in the interior of the cartridge are pressed forward and pass through the valve slots 43 into the two valve channels 28 and 29 and from there into the mixing nozzle 23. There they are mixed in the mixing channel 52 and can pass through the Exit opening 45 are applied to the desired location.

As soon as the actuating member is released to interrupt the dosing process, the changeover part 22 goes to position 11 and compressed air is fed into the front connecting piece 15. The front wall 33 is pressurized with compressed air and brings the cartridge 2 back into the rear position. The valve slots 43 are covered again by the cartridge mouth 13. In addition, the valve channels 28, 29 are sealed by the valve lugs 30 with their sealing lips against the cartridge chambers 3, 4. So no more substances can get into the mixing nozzle 23.

With inexpensive components, a clean separation of the components is guaranteed. The cartridge 2, which is to be regarded as a disposable part, does not require a thread, which would make the manufacturing process very expensive. The partition 7 in the cartridge 2 continues up to its mouth 13, is received by the slot 27 of the valve piece 14, the partition wall 26 of which up to the static mixing channel 52 of the mixing nozzle 23 ensures separation of the components. The mixing nozzle 23, which, like the cartridge 2, is to be regarded as a disposable part, does not require an expensive thread.

The compressed air can be switched off again; the cartridge is locked in the rear position. For this purpose, locking means not shown in the figure are to be provided. For this purpose, locking notches in the cartridge wall, for example, are suitable, into which the sealing caps 30 can snap.

A reduced pressure of the compressed air is sufficient to move the cartridge 2 backwards. This is particularly important when removing the cartridge 2. Otherwise, the cartridge 2 would be conveyed out of the support tube 1 like a bullet when the rear cover 9 was removed.

Disposable pressure bottles, which can be used in a pressure range of 4 - 6 bar, are ideally suited as blowing agents. For example, highly viscous 2-component adhesive mixtures can be processed without any problems.

So that the pistons 5, 6 are actuated as lightly as possible can be made from a material that has the lowest possible coefficient of friction. Polybutylene terephthalate (PBTB) is ideally suited for this purpose, since it is also characterized by excellent dimensional stability and high creep resistance. Polyethylene, polypropylene or polybutylene terephthalate are the most suitable materials for the cartridge 2 or at least its intermediate wall 7. These materials are not only very inexpensive and easy to cut, but are also characterized by high chemical resistance.

7 shows a further, purely mechanical embodiment variant of the invention. In this embodiment variant, a handle 37 is built on the back of the cover 9. The front part is identical to that of the pneumatic version, except that a return spring 34 is provided as the return element. In the handle 37 there is a toothed rack 36 for actuating the pistons 5, 6. This is moved forward by means of a pawl 40 which is fastened to an actuating lever 38. To prevent the rack 36 from sliding back, a pawl 41 is provided. On the rear part of the rack 36 there is a reset handle 39 and on the front part a stamp plate 46, which serves to distribute the pressure exerted by the rack 36 to the round piston 5 and, via the knife 19, also to the piston 6.

The purely mechanical version works as follows:

Pushing the actuating lever 38 moves the pawl 40 forward. As a result, it exerts pressure on the tooth shoulder 47 and the rack is moved forward until the pawl 40 leaves the tooth shoulder 47. This feed movement is dimensioned such that the cartridge 2 is moved forward in the first part of the feed path until the valve slots 43 open into the interior of the chamber (cf. FIG. 4). The second part of the feed path serves to allow the piston assembly 5, 6, 19 to penetrate a certain distance into the interior of the cartridge chambers 3, 4, so that a certain amount of substance is pressed into the mixing nozzle 23. As soon as the pawl 40 disengages, the return spring 34 presses the cartridge 2 backwards, so that the valve slots 43 are sealed again by the cartridge mouth 13. In order to prevent the push rod 36 and thus the piston assembly 5, 6, 19 from sliding back further, a pawl 41 engages. The transmission ratio of the pawl 40 to the pawl 41 is to be selected such that on the one hand the valve slots 43 are opened or sealed cleanly and on the other hand a sufficient amount of substance can be applied.

When inserting a new cartridge, the rack 36 must be brought fully back into the rear position. For this purpose, the reset handle 39 is rotated by 90 °, so that the toothed rack 36 can no longer be blocked by the pawl 41, and then brought into a starting position by a pulling movement.

Finally, a few words about filling the cartridge. So that a bubble-free filling is guaranteed; the use of immersion tubes is recommended. These are introduced into the mouth 13 of the cartridge for filling. In the case of highly viscous substances in particular, it is important that the air displaced by the substances can escape as well as possible. It is therefore advisable to evacuate the inside of the cartridge before and during filling.

However, convenient filling is not possible if the openings of the cartridge mouth are as small as in the practical embodiment of the known device described at the beginning. Thanks to the advantageous design of the valve according to the present invention, the openings of the cartridge mouth can be provided sufficiently large to ensure better filling of the cartridges 2.

In addition, the round-bottom pistons and the annular pistons can be provided with sealing sleeves on the compressed air side, which prevent the penetration of air into the resin or the hardener.

• a) Beim Abfüllen der Kartusche läuft die Fliessfront in der ringförmigen Kammer asymmetrisch, so dass Lufteinschlüsse unvermeidlich sind,
• b) weil infolge der Wandstärke, die Oberfläche der Trennwand auf der Seite der Ringkammer grösser ist als auf der Seite der zentralen Kammer, ist bei gleichem Kolbendruck der Druck innerhalb der Ringkammer grösser als innerhalb der zentralen Kammer. Letztere wird deshalb in der Mitte etwas gebeult, was zu Stabilitätsproblemen und damit zu Dosierfehlern führt.
• c) eine Kartusche mit koaxialen Kammern ist verhältnismässig teuer in der Herstellung.
• d) handelsübliche Kartuschen sind in der Regel nicht verwendbar.
• e) darüber hinaus muss für jedes gewünschte Mischverhältnis eine spezielle Kartusche gebaut werden.

The coaxial arrangement of the cartridge chambers described above allows an extremely compact structure, but the following difficulties are encountered:

• a) When filling the cartridge, the flow front runs asymmetrically in the annular chamber, so that air pockets are inevitable,
• b) because due to the wall thickness, the surface of the partition on the side of the annular chamber is larger than on the side of the central chamber, the pressure inside the annular chamber is greater than within the central chamber at the same piston pressure. The latter is therefore slightly dented in the middle, which leads to stability problems and thus to metering errors.
• c) a cartridge with coaxial chambers is relatively expensive to manufacture.
• d) Commercial cartridges are generally not usable.
• e) In addition, a special cartridge must be built for each desired mixing ratio.

The disadvantages just mentioned are eliminated in a further embodiment variant shown in FIGS. 8a and 8b in the rest or working position. In this embodiment variant, the housing consists of a housing tube 54 with a front closure cover 55 fastened by means of a union nut 57 and a rear closure cover 56 fastened by means of screws 90. Two cartridges 58's are screwed with their threaded muzzle tubes 59 onto a cartridge carriage 60 arranged axially displaceably in the housing tube 54. This is provided with an O-ring 61 on its outer edge. The cartridge opening leads into a borehole 63 which, after a short axial course, is directed radially against the central axis of the carriage 60 and opens at the wall of the central bore 62 in the carriage 60.

The valve piece 64 is slidably mounted in the bore 62 and screwed to a fastening cover 65 and secured by means of a lock nut 66. The fastening cover 65 is in turn screwed onto the front closure cover 55. The valve piece 64 has a valve head 68 at its rear end. Two valve channels 69 open into the side wall of this valve head 68 and lead radially inward, in order then to run axially forward into a mixing nozzle 23 fastened to the front end of the valve piece 64. A separating web 70 protruding at the front of the valve piece 64 extends into the mixing nozzle 23 and serves for better separation of the components before they enter the static mixing channel 52.

On the rear cover 56, a holder H is provided with an operating lever B for holding the press and for admitting the propellant gas. With the help of control lever B, a valve, not shown, is actuated for metering the drive gas. A pressure gauge 87 for monitoring the pressure conditions can also be provided on a fastening part 86 on the rear cover 56.

It is advantageous if the cartridges 58 - as provided in this exemplary embodiment - are already equipped with ejection pistons 71. These then serve as a rear closure for the cartridges during transport and storage. In this way it can be avoided that the usual sealing caps have to be exchanged for squeezing pistons. In the case of such manipulations, substances can flow out of the cartridge and reach unwanted places inside or outside the housing.

The pistons are in turn made up of several parts. Firstly, there are squeeze-out pistons 71 which can optionally be supplied with the cartridges. To actuate these squeezing pistons, drive pistons 72 ... 75 are provided; which are designed as drive parts 72, 74 on the parts directed against the driving air and on the parts which can be introduced into the interior of the chamber and directed against the drive pistons 71 as plunger parts 73. The squeeze-out pistons 71 are disposable and are replaced when the cartridge is used up, while the drive pistons 72 ... 75 can be provided for repeated use. The part which remains outside the cartridges and which is upstream of the drive part 74 serves as a sealing part 75, the function of which will be explained further below. In the case of the drive pistons 72 ... 75, the piston parts 72, 73 located in the interior of the cartridge are referred to as "inner drive pistons" and the piston parts 74, 75 remaining outside the cartridge are referred to as "outer drive pistons". A ring-shaped blade 80, referred to as a "ring knife", not only couples the inner drive pistons 72, 73 and thus also the squeezing pistons 71 to one another, but also produces a coupling between the inner and outer drive pistons (72, 74 and 74, 75) . In the exemplary embodiment, both the plunger parts 73 and the sealing part 75 are constructed separately from the corresponding drive parts 72 and 74 and are connected to these by screws 88. Thanks to this separate construction, the piston-coupling ring knife 80 can be conveniently inserted and, if necessary, easily replaced. On the other hand, there is the option of driving pistons 72 ... 75, i.e. Manufacture drive parts 72, 74, plunger parts 73 and sealing part 75 together with the knife as a blade / piston unit in one piece. Thermoplastic with high compressive strength could be used as a material for this.

Finally, the connecting piece 85 should also be mentioned, through which propellant gas can be let into the interior of the housing tube 54 for the purpose of resetting the drive pistons 72.

The drive pistons 72 ... 85 are shown in detail in FIGS. 9a, 9b. Fig. 9a shows an exploded view of the drive piston 72 ... 85 in a separate construction and Fig. 9b shows a corresponding longitudinal section. The plunger part 73 is provided with a slot 76 for receiving the ring knife 80. On its circumference it has a radially directed sealing lip 77, which is somewhat upstream of the blade slot 76 in the direction of actuation of the pistons and whose function will be explained later. One threaded hole 81 is used to receive a fastening screw 88 (see FIG. 10). In the outer drive pistons 74, 75 shown in FIGS. 9a, 9b, two bores 79 serve to receive the inner drive pistons 72, 73, a gap for the passage of the cartridges having to be taken into account when selecting the bore diameter. The bores of the sealing part 75 also each have a sealing lip 78. This is directed radially inward and is arranged such that they are offset in relation to the radially directed sealing lips 77 of the plunger part 73, in such a way that the sealing lips 78 of the sealing part 75, the sealing lips 77 of the tappet part 73 are somewhat upstream as seen in the actuation direction of the pistons. Finally, the threaded holes 91 (FIG. 9a) in the sealing part 75, which are used for the connection to the drive part 74, should also be mentioned.

Fig. 10 shows a detailed view of the drive piston 72 ... 75 with inserted cartridge wall 58. One recognizes the plunger part 73, which is by means of a screw 88 on the cylindrical Drive part 72 of the inner drive piston 72, 73 is screwed tightly and is connected to the outer drive piston 74, 75 via the ring knife 80.

The radially directed sealing lip 77 prevents propellant gas from penetrating as far as the squeezing piston 71. Otherwise there would be the danger that the ejection piston 71 lying loosely on the plunger part 73 would be acted upon by the advancing propellant gas, would lift off the plunger part 73 and would travel a different distance than the other ejection piston 71. Then the compliance with the prescribed mixing ratio would no longer be guaranteed.

The considerable squeezing forces that arise when the drive pistons are actuated lead to the cartridge being inflated. In addition, unevenness and minor deviations from the geometric shape can be expected with the cartridge wall 58. For these reasons, there is a risk that the cartridge wall 58 will rise in places from the ejection piston 71 or also from the tappet part 73. The consequences would be serious in both cases. If the cartridge wall 58 lifts off from the plunger part 73, there is - as just mentioned - the risk that the squeezing piston 71 lifts off the plunger part 73 and the mixing ratio is no longer guaranteed. If the cartridge wall 58 lifts off the ejection piston 71, dosing substance can penetrate into the area of the drive piston (72 ... 75).

With its radially inwardly directed sealing lip 78, the sealing part 75 now exerts a counterpressure in the area between the plunger part 73 and the pressing-out piston 71 and in this way prevents the latter from being lifted off the cartridge wall 58.

11 shows an embodiment variant of a drive piston unit. The plunger part 73 has a Y-star-shaped slot 92 for receiving correspondingly arranged blades 89. The plunger part 73 provided for the upper borehole 79 in the sealing part 75 is shown separately, while the other plunger part 73 is located in the corresponding lower borehole 79. The knives 89 are secured by the drive parts 72, 74.

Fig. 12 shows an exploded view of the valve attachment. Two cartridges 58 can be screwed to the cartridge carriage 60. In order to achieve a higher degree of tightness, this contains an O-ring 61 on its outer circumference. The front closure cover 55 is fastened to the housing tube 54 with the union nut 57. The front part of the valve piece 64 protruding from the cartridge slide 60 is provided with a thread 67 and is screwed onto the front cover 55 by means of the fastening cover 65 and secured by means of the locking nut 66. A return spring 84 pushes the cartridge carriage 60 into the rear position.

Fig. 13 shows a representation of the drive piston 72 ... 75 when penetrating the cartridges 58. It can be seen that the cartridges 58 are cut when leaving the piston assembly 72 ... 75.

The mode of operation of this device can best be seen from FIGS. 8a, 8b:

When operating the control lever B, the drive pistons 72 ... 75 are acted on by propellant gas. The pressure exerted by the propellant gas on the drive pistons 72 ... 75 is transferred to the press-out pistons 71. The area of the drive pistons 72 ... 75 is larger than that of the squeeze-out pistons 71 by the area of the outer drive pistons 74, 75, so that a pressure ratio corresponding to the ratio of the piston areas takes place.

This is of particular importance for pneumatic systems. In various countries, only relatively low pressures for LPG containers are permitted within the framework of the legal safety regulations. In Switzerland, for example, a maximum pressure of just 6 bar is permitted. In practice, it has now been shown that such a low propellant pressure is inadequate in various cases, especially with very viscous dosing substances. Thus, the embodiment variant shown in FIGS. 8a, 8b - not least because of the high pressure forces required for the actuation of the mixing nozzle 23 - requires at least an extrusion pressure of 8 bar in order to ensure trouble-free working with the piston press. Thanks to the pressure ratio, you can work with commercially available LPG bottles for which a maximum pressure of 6 bar is prescribed.

Now a few words about how the valves work. As long as the cartridge is in the rear position (FIG. 8a), the channels 63 present in the cartridge slide 60 are separated from the channels 69 of the valve piece 64, i.e. the valve is closed. The contents of the cartridge cannot be squeezed out and the pressure on the squeezing pistons moves the cartridges together with the cartridge slide forward. In the front position (FIG. 8b), the channels 63 present in the cartridge slide are now connected to the channels 69 of the valve piece 64, in other words the valve is open. The inner drive pistons 72 can now penetrate into the interior of the cartridge while cutting the rear part of the cartridge 58 together with the squeezing piston 71, so that the substances are pressed out through the mixing nozzle 23. If the operating lever is released again, the return spring 84 presses the cartridge carriage 60 together with the cartridges 58 backwards and the valve 60, 64 is closed again. So every time work is interrupted, the valve closes automatically.

For devices that work with high pressures, the embodiment variant of a metering valve shown in FIGS. 14a and 14b offers a particularly inexpensive and easy-to-use solution. The rear part of the piston press, including the structure of the piston, is identical to the embodiment variants shown in FIGS. 8a ff. The same reference numbers have also been used, so that there is no need to repeat the description in this regard. In contrast, the front part of the piston press and the cartridges differs significantly from the one shown so far.

Instead of the cartridge carriage 60, valves 114 are integrated in the cartridges 58 and are guided there axially displaceably in the outlet tube 59 thereof. The mouth pipes 59 are in turn also guided axially displaceably in a cartridge guide 103. This is screwed onto a housing front part 100. Here, an annular flange 106 serves to secure the screw seat. The front housing part 100 is fastened to the housing tube 54 by means of screws 101. A union nut 108, which can be screwed onto the front end of the cartridge guide 103, clamps the end flange 107 of a mixing nozzle 23 at the front end of the cartridge guide 103. A separating web 105 provided on the front of the cartridge guide 103 ensures that the components guided out of the cartridge guide 103 first come together in the static mixing channel 52 of the mixing nozzle 23. Instead of a union nut 108, which is an additional component, a recess could also be provided in the front part of the cartridge guide 103 for snapping the mixing nozzle 23, so that it could be attached to the cartridge guide 103 like a bayonet.

The front part of the piston press is shown explosively in detail in FIG. 15. The holes 104 in the cartridge guide 103 serve to receive the two outlet tubes 59 of the cartridges 58. A return spring 84 presses the cartridge 58 backwards in the rest position. Valves 114 are arranged in the outlet pipes 59, the valve heads 110 of which are fixed in a notch 102 in the rear cartridge position. The longitudinal shaft 115 of a valve 114 is formed by three ribs arranged in a star-like manner with respect to one another.

When the cartridges 58 are pressed into the front position, the valve webs 115 rest against the shoulder 107 of the mixing nozzle 23, which also serves as a support part for the valves 114, and the valve heads 110 are pressed into the interior of the cartridge. This position, in which the valves 114 are open, is shown in Fig. 14a.

The valves thus function as follows: In the rest position (FIG. 14 b), the cartridge 58 is in the rear position and the valve heads 110 are fixed in the notches 102. The device can be transported or stored. The valves are closed; the contents of the cartridge cannot leak.

When compressed air is applied to the pistons (71 ... 75), the valves 114 are initially engaged in the orifices 59, i.e. closed (Fig. 14b). The cartridge content cannot flow out, so that the pressure acts on the cartridges 58 as a whole and sends them forward. The valve stems 115 are supported on the shoulder 107 of the mixing nozzle 106 and cannot follow the cartridge movement. The valve heads 110 therefore get into the interior of the cartridges 58 during the cartridge movement. When the cartridges 58 have reached the front position (FIG. 14 a), the cartridge contents are cleared into the mixing nozzle 23. This corresponds to the working position; the pressure acts as a squeezing pressure.

If the compressed air is discharged again, the return spring 84 presses the cartridges 58 back again into the rest position (FIG. 14b). At the same time, the excess pressure remaining in the interior of the cartridge presses the valves 114 forward, where the valve heads 110 snap back into the notches 102.

• a) Beim Einfüllen des Kartuscheninhalts sind Lufteinschlüsse unvermeidlich. Diese werden infolge des Kolbendrucks komprimiert,
• b) Die Kartuschenwände werden durch den Kolbendruck gedehnt,
• c) Die Rückstellfeder drückt die Kartuschen 58 nach Ablassen des Kolbendruckes wieder in die hintere Position. Hierbei erfahren die äusseren Antriebskolben 72...75 am Gehäuserohr 54 einen Reibungswiderstand und üben infolgedessen Druck auf die Substanz aus.

Such an overpressure inside the cartridge is built up as follows:

• a) Air pockets are inevitable when filling the cartridge contents. These are compressed due to the piston pressure,
• b) The cartridge walls are stretched by the piston pressure,
• c) The return spring presses the cartridges 58 back into the rear position after releasing the piston pressure. Here, the outer drive pistons 72 ... 75 experience a frictional resistance on the housing tube 54 and consequently exert pressure on the substance.

The in lit. a) to c), the pressure components cause the substance in the interior of the cartridge to exert pressure on the valve heads 110, drive them back into the orifices 59 and snap them into place.

The device according to the invention is also suitable for systems with more than two chambers. A system with a cartridge carriage into which more than two cartridges can be inserted is very flexible, analogous to the embodiment variants shown in FIGS. 8 and 14. These systems can be designed for a maximum number of screw-in or slide-in cartridges (for example, 9 of them), but depending on the application, only a part of the cartridges (for example, 3 of them) can be inserted into the cartridge carriage or the cartridge guide. It goes without saying that the unused cartridge spaces must be sealed.

The cartridges can also be arranged in the form of cartridge sets in which the cartridges are connected to one another in the vicinity of the cartridge mouths via a connecting flange (similar to that in FIG. 15). In this way, confusion when selecting and inserting individual cartridges of a cartridge set can be prevented.

The exemplary embodiments explained so far make it clear that both the coupling principle of the pistons and the functional principle of the valves offer a multitude of possible variations allows. In addition, almost all components can be made from inexpensive plastic material and are easy to assemble. The cartridges, or possibly their subchambers, are advantageously already equipped with valves and pistons when the contents of the cartridge are being filled. Valves and pistons prevent the contents of the cartridge from leaking and ensure safe transport.

A further embodiment variant is referred to below in somewhat more detail. In this further embodiment variant, the cylindrical cartridge body is divided into subchambers by one or more longitudinal dividing walls or dividing walls, as is shown, for example, in EP-A-0 119 847 mentioned at the beginning. However, in the case of the design variants shown in the cited document, the blades only serve to prepare the partition wall by slitting in a suitable manner in such a way that it is rolled up with corresponding deformation means, or otherwise releases the actuation area of the piston drive or coupling means. According to the invention, however, the pistons can be coupled directly via the blades, so that the deformation and coupling means are dispensed with and the usable space in the housing is saved. It is no longer a problem to transfer the embodiment principle shown in FIGS. 9a and 9b to an embodiment variant with longitudinal partition walls.

In this case, the outer drive piston contains, instead of two bores for two cartridges, only one bore for a single cartridge, even if it is divided into subchambers. The squeezing pistons are now semicircular in accordance with the cross section of the subchambers and, according to the invention, are coupled via blades, as is shown in the previous exemplary embodiments. If the piston drive is on a pneumatic basis, a pressure ratio should be an advantage. In the present case, the outer drive piston has an annular shape, since the divided cartridge is best arranged in the center. A blade provided for coupling the pistons can in turn be inserted in a slot provided in the tappet and sealing part. For a variant with only two subchambers, the pistons provided for the subchambers and the outer drive piston can be coupled with a straight, knife-like blade.

The arrangement principle for the valves shown in FIG. 14a can also be very easily transferred to the present case. Instead of two round, separately arranged chambers, one encounters two semicircular partial chambers that are only divided by a simple partition. The cartridge outlet mouths are advantageously also arranged round and somewhat spaced. Instead of a round valve channel, semicircular or otherwise suitable shaped cartridge openings can also be provided. It should be emphasized once again that the piston coupling principle and the valve system can also be easily transferred to devices with cartridges divided into more than two subchambers.

On the other hand, both the piston coupling system and the valve arrangement according to the invention can be used for systems with only a single single-chamber cartridge. In such a variant, the piston coupling system is used for pressure transmission if, for example, a viscous flowing substance is to be squeezed out and only a low propellant pressure is available for safety reasons. Thanks to the automatic valve system, open valves can also be a thing of the past with single-chamber systems.

As can be seen from the previous explanations, both the piston coupling system and the valve system can be adapted to any cartridge shape.

In general, the invention offers space for a large number of variations. For example, it is not absolutely necessary for the piston to be coupled via the cutting means themselves. If cutting means which are unsuitable for the piston coupling, such as, for example, particularly fine blades or wire prove to be particularly advantageous in certain applications, the coupling can also be carried out by means of a coupling flange arranged behind the cutting means. However, it is a prerequisite that the thickness of the coupling flange corresponds approximately to that of the cutting means, so that it can be easily passed through the slot created by the cutting means in the cartridge wall and does not produce any strong friction or inadmissible deformation of the wall parts adjacent to the slot.

• a) auf einen Kartuschenschlitten übertragen werden, der Teil eines Ventiles bildet, wie dies beispielsweise in Fig. 8a, 8b gezeigt ist.
• b) zur Steuerung oder Betätigung von Ventilen verwendet werden, die unabhängig von den Kartuschen oder vom gegebenenfalls vorhandenen Kartuschenschlitten aufgebaut sind und deren Bewegungsrichtung sich von derjenigen der Kartuschen unterscheiden kann.

The idea of the invention also permits numerous variations with regard to valve control. The relative movement between cartridges and housing can

• a) are transferred to a cartridge carriage which forms part of a valve, as is shown, for example, in FIGS. 8a, 8b.
• b) are used to control or actuate valves which are constructed independently of the cartridges or of the cartridge carriage which may be present and whose direction of movement can differ from that of the cartridges.

The control of valves due to the relative movement of the cartridges in relation to the housing ensures that they are only opened when there is sufficient squeezing pressure inside the cartridge.

The feature of the invention that the valve heads integrated into the cartridge outlet pipes and snap back into place after each piston actuation, allows a cartridge that has been started to be removed from the device and kept until it is reused, the valves 114 serving as front and the ejection pistons as the rear caps. A cartridge change therefore only requires a simultaneous change of cartridge guide and mixing nozzle, both of which are to be regarded as disposable elements.

An electric spindle drive can also be used instead of propellant gas or a pawl drive. Since this is very cheap, a separate drive can also be provided for each cartridge chamber. In this case there is no need to connect the pistons by means of blades. When controlling the spindle drive, however, it must be ensured that the valves close again and can snap into the mouth of the cartridge. For this purpose, the spindle drive must either be automatically operated a few revolutions in the opposite direction at the end of a machining process or otherwise relieved - for example by lifting the spindle off the rack.

Claims (17)

1. A device for squeezing out and mixing liquid or pasty substances from cartridges (58), with a housing (54) with an opening for inserting the cartridges (58), means for positioning the cartridges (58) in the housing (54) in a position in which the forward outlet openings of the cartridges communicate with openings in the front part of the housing, a mechanically coupled piston assembly (5, 6, 19, 72, 73, 74, 75, 80, 88) which is displaceable in the housing (54) in the longitudinal direction of the cartridge, characterised in that, in order to squeeze out cartridges (58) with outer walls made of cuttable material, the piston assembly is provided with through-slots for the cartridge walls (58), the slots in the region of the cartridge walls being bridged by a blade (80), the cutting edge of which is directed towards the cartridge wall and is arranged with respect to the dispensing movement of the piston assembly on the same level as the piston sealing ribs (77) or behind them, said blade and/or a narrow crosspiece arranged directly behind it and perpendicular to the cutting plane connecting the piston parts which are separated by the through-slots to each other in a stable fashion.

2. A device according to Claim 1, characterised in that the piston assembly (5, 6, 19, 72, 73, 74, 75, 80, 88) is guided in the housing (54).

3. A device according to Claim 1 or 2, characterised in that the guidance of the piston assembly (5, 6, 19, 72, 73, 74, 75, 80, 88) in the housing (54) is gas-tight and liquid-tight and the piston assembly is driven pheumatically or hydraulically.

4. A device according to one of the preceding Claims, characterised in that the sealing lips (77, 78) are arranged offset with respect to each other on adjoining parts (73 or 75) of the piston assembly, the sealing lips (78) which engage the cartridge walls externally preferably being located in front of those engaging internally.

5. A device according to one of the preceding Claims, characterised in that the housing (54) is provided at the front with a removable cover (100) for introducing the cartridges (58).

6. A device for squeezing out and mixing liquid or pasty substances from cartridges (58), with a housing (54) with an opening for inserting the cartridges (58), means for positioning the cartridges (58) in the housing (54) in a position in which the forward outlet openings of the cartridges communicate with openings in the front part of the housing, characterised in that the means for positioning the cartridges (58) are formed by a holder (60) which is displaceable in the housing (54) in the longitudinal direction between two end positions, or by a holder (103) in which the cartridges are mounted so as to be displaceable between two end positions in the longitudinal direction of the housing, and that the housing (54) or a cover (100) closing it at the front is provided with means which open the cartridge closures in the forward end position of the holder (60) or of the cartridges (58).

7. A device according to Claim 6, characterised in that the holder (60) or the cartridges (58) is/are displaceable into their forward end position against the force of a restoring spring by the dispensing pressure of the piston.

8. A device according to Claim 6, characterised in that the holder (60) or the cartridges (58) are displaceable into their forward end position by the dispensing pressure of the piston and can be restored from the forward end position hydraulically or pneumatically.

9. A device according to one of Claims 6 to 8, characterised in that the piston assembly (5, 6, 19, 72, 73, 74, 75, 80, 88) is guided in the housing (54) so as to be gas-tight.

10. A device according to one of Claims 6 to 9, characterised in that the holder (60) is guided in the housing (54) so as to be gas-tight.

11. A device according to Claims 9 and 10, characterised in that the housing has a connecting socket (85) for a pneumatic or hydraulic drive medium between the forward end position of the pistons (73, 75) and the holder (60), and that the piston assembly (73, 74, 75, 80, 88) can be pressed backwards out of the (empty) cartridges (58) by said drive medium against the holding force of the cartridges (58) in the holder (60).

12. A device according to one of Claims 6 to 11, characterised in that in the case of cartridges (58), the closure of which is formed by a valve head (110) with a forward-pointing valve stem (115), the forward housing end or the cover closing it or a part (107) connected therewith is constructed so that it forms a stop (107) for the valve stem (115) before the end position is reached, and opens the valve (110).

13. A device according to Claim 12, characterised in that the sealing seat of the valve plate (110) is formed by a catching notch in the outlet sleeve (53) of the cartridge (58).

14. A device according to one or more of the preceding Claims, characterised in that a mixing nozzle (23) is detachably fastened to the forward part of the housing or the cover (100) closing it, which nozzle, either directly or by means of an intermediate part which is likewise detachably fastened, communicates with the outlet sleeves (59) of the cartridges (58).

15. A device according to one or more of the preceding Claims, characterised in that the cartridges (58) are made of polyethylene, polypropylene or polybutylene terephthalate.

16. A device according to one or more of the preceding Claims, characterised in that the piston assembly (5, 6, 19, 72, 73, 74, 75, 80, 88) is made of polybutylene terephthalate.

17. A device according to Claims 1 and 6 and one of Claims 7 to 16.

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