Coaxial cartridge with predefined expansion points for force-free dispensing of a flowable multi-component compound

Description

FIELD OF THE INVENTION

[0001] The invention relates to a coaxial cartridge designed to receive and store a first and a second component of a flowable multi-component compound in separate coaxial chambers and to be inserted into a support structure for extruding this compound from the cartridge. Although the explanation of the invention generally refers only to these two chambers for two components, additional (sub-)chambers for additional components of the multi-component compound can always be provided inside the cartridge.

[0002] Various cartridge concepts are known in the prior art for accommodating at least two components of flowable materials in separate chambers, which can be dispensed using a dispenser. With regard to the arrangement of the chambers, a distinction is made between coaxial cartridges and cartridges or foil containers with adjacently arranged individual cartridges or foil bags for the various components of a multi-component material. The multi-component material can, for example, be a sealing or fixing compound such as mortar, adhesive, and many more.

[0003] To ensure a high, consistent mixing quality of the two dispensed mass components, suitable support structures are usually required for the cartridges into which the cartridges are inserted during the dispensing process. These support structures absorb the pressure exerted by the cartridges during the dispensing process and prevent elastic expansion of the cartridges, which are usually made of plastic and would therefore yield to high pressure during the dispensing process without the support structure.

[0004] Due to the almost identical pressure in both chambers and the excess pressure compared to the atmospheric pressure outside the cartridge, thick-walled plastic coaxial cartridges typically exhibit elastic expansion only in the outer wall of the cartridge during the dispensing process. This can lead to undesirable pumping behavior of the cartridge, which can cause mixing problems and, consequently, poor curing of the compound.

[0005] Such coaxial cartridges are known, for example, from DE19730645C1, US6,464,112B2 and US2007 / 278251A1.

[0006] When the outer wall of a thick-walled plastic cartridge elastically expands radially during the dispensing process, restoring forces are created within it. If the dispensing process is interrupted - for example, when moving on to the next borehole when several boreholes are to be filled in succession with the contents of the cartridge - these can lead to uneven pumping behavior in the cartridge, which is caused by these elastic restoring forces. After an interrupted dispensing process, the pressure in the outer chamber of the cartridge is relieved either by the component contained flowing out through the cartridge outlet or by the outer piston located in this chamber being relieved. This causes the piston to be offset relative to the inner chamber, which leads to corresponding mixing disturbances during the subsequent dispensing process.

[0007] To counteract this, a suitable support structure must be used to prevent elastic deformation of the cartridge's outer wall during the dispensing process. This support structure must fit as tightly as possible against the cartridge to minimize the potential pumping volume: During pumping, the outer piston can only retract according to the volume of any annular gap between the support structure and the cartridge's outer wall, because the cartridge's outer wall could only expand elastically within this annular gap during the dispensing process. It is also important to ensure that the support structure is sufficiently rigid to prevent pumping due to deformation of the support structure itself.

[0008] Identical diameters (i.e., the inner diameter of the support structure is the same as the outer diameter of the cartridge) therefore offer the greatest possible protection against disruptive pumping behavior and the associated mixing disturbances of the extruded compound. However, identical diameters hinder easy insertion and removal of the cartridge into and from the support structure. This, in turn, requires a slightly larger inner diameter of the support structure compared to the outer diameter of the cartridge, i.e., the aforementioned annular gap between the cartridge and the support structure, which promotes disruptive pumping behavior. Pumping presents a major challenge, especially with large-volume cartridges and containers.

[0009] It is therefore an object of the present invention to provide a coaxial cartridge for storing a flowable multi-component mass and for insertion into a support structure for pressing this mass out of the cartridge, as well as a corresponding system comprising a cartridge in combination with a support structure, with which the described disruptive pumping behavior of the cartridge based on elastic restoring forces can be reduced or even completely prevented.

[0010] This object is achieved by a coaxial cartridge according to claim 1 and by a corresponding system and method according to the independent claims. Further embodiments are specified in the dependent claims. All further features and effects mentioned in the claims and the description for the cartridge also apply mutatis mutandis to the system and method, and vice versa.

[0011] According to a first aspect, a coaxial cartridge is provided for storing a flowable multi-component compound and for insertion into a support structure for extruding this compound from the cartridge. The multi-component compound comprises at least a first component and a second component, which are stored separately in the cartridge and are to be mixed with each other only upon dispensing from the cartridge. This can, in particular, be a sealing or fixing compound such as mortar, adhesive, and the like.

[0012] The cartridge comprises a hollow cylindrical inner wall and a hollow cylindrical outer wall arranged coaxially (i.e. with the same cylinder axis) around this, so that the cartridge has an inner chamber delimited radially by the inner wall for receiving the first component of the multi-component mass and an outer chamber arranged radially between the inner wall and the outer wall for receiving the second component of the multi-component mass. Even if the following explanation of the invention and the claims mostly only refer to these two chambers for two components, further (sub-)chambers for further components of the multi-component mass can always be provided inside the cartridge, which are dispensed from the cartridge in the same squeezing process and are mixed with the first and second components.

[0013] On one of its two (axially) opposite ends, the cartridge has a cartridge front wall that axially delimits the inner chamber and the outer chamber and has a dispensing opening for the first component in the inner chamber region and a dispensing opening for the second component in the outer chamber region. The cartridge front wall can, in particular, be firmly connected to the inner and outer walls of the cartridge. For this purpose, it can, for example, be formed integrally with at least the inner wall or be attached to it in the form of a separately manufactured cartridge lid.

[0014] The cartridge further comprises an inner piston that closes the inner chamber at the rear (i.e., toward the other end of the cartridge) and is axially movable therein, as well as an outer piston that also closes the outer chamber at the rear and is axially movable therein. The inner wall of the cartridge can be dimensionally stable, in particular thick-walled, in such a way that it radially supports both the inner piston and the outer piston and thus guides their axial movement.

[0015] At least one predetermined expansion point is formed in the outer wall of the cartridge. Each predetermined expansion point extends axially from end to end of the cartridge and is plastically deformable to such an extent that, during the dispensing process, it immediately yields to pressure acting on the outer wall from the inside by plastically expanding. Furthermore, the cartridge is designed to be dimensionally stable, for example, with thick walls, that when the compound is pressed out of the cartridge by axially displacing the inner and outer pistons (referred to as the dispensing process for short), it essentially retains its shape in the areas where no predetermined expansion points are formed. It is therefore a so-called hard cartridge that retains its cylindrical shape overall.

[0016] During the extrusion process, the respective desired expansion point can plastically expand, for example, radially outward and / or in the circumferential direction of the outer wall until it rests against the support structure, for example. This can slightly increase both the inner and outer diameters of the outer wall and at least partially close an annular gap that existed between the cartridge and the inside of the support structure when the cartridge was inserted into the support structure.

[0017] Through plastic deformation in the area of ​​the expansion joints, the extrusion pressure acting from the inside onto the outer wall can be fully absorbed. Elastic deformation of the outer wall can thus be effectively reduced or even completely avoided, thus also eliminating the disruptive pumping behavior mentioned above. The selection of a suitable number of expansion joints and their dimensions must be made for each specific application, depending on factors such as the material, pressure applied, and overall size of the cartridge. The wall thicknesses of the inner and outer walls must also be selected based on these specific application conditions and the functionality described herein.

[0018] One idea of ​​the present invention is therefore to provide a coaxial cartridge that is slightly smaller in diameter than the support structure to facilitate insertion of the cartridge into the support structure. The cartridge has specifically designed expansion points in its outer wall. These expansion points have a primary axial orientation and allow the cartridge to be pressed against the support structure through plastic deformation even at very low pressures, thereby significantly reducing or even eliminating pumping behavior of the cartridge in the support structure based on elastic restoring forces.

[0019] In particular, several predetermined expansion points can be evenly distributed along the circumferential direction of the outer wall, for example, by being designed and arranged symmetrically with respect to the axial direction. Alternatively or additionally, the several predetermined expansion points can be identical to one another and / or each extend in a straight line parallel to the cylinder axis of the cartridge. All of these properties can contribute to uniform pressure absorption in the outer wall, thus particularly effectively preventing disruptive recovery behavior (pumping).

[0020] In particular, the outer bulb can have an elastic sealing lip in its edge region adjacent to the outer wall, which is designed to form a sealing contact with the outer wall through elastic pre-compression before and during the entire extrusion process. This compensates for an increase in the diameter of the outer wall associated with the expansion of the predetermined expansion points.

[0021] According to one embodiment, at least one (and ideally all) of the predetermined expansion points described herein are formed by reducing the wall thickness of the outer wall in the region of the predetermined expansion point, for example, to half, one-third, one-quarter, one-fifth, or one-tenth of the wall thickness. At least one of the predetermined expansion points can be formed by an external groove in the outer wall.

[0022] In this and any other embodiment, the coaxial cartridge, with the exception of its movable inner and outer pistons, may be manufactured in one piece, for example by injection molding or moulding.

[0023] According to one embodiment, the hollow cylindrical inner wall and the hollow cylindrical outer wall each have a circular cross-section. However, this is not absolutely necessary for the functional principle presented herein, so that other cross-sectional shapes, such as elliptical or rectangular, can in principle be implemented just as well.

[0024] According to one embodiment, at least the inner wall and / or the outer wall of the cartridge are made of plastic. In particular, the entire cartridge can be made of plastic, with its individual components being made of the same or different types of plastic. However, other materials, such as metal, can also be used.

[0025] In a specific embodiment, the cartridge front wall has a connecting piece on its side facing away from the inner and outer chambers, into which the discharge openings of the inner and outer chambers respectively open and which is designed to connect a mixer for mixing the various components of the multi-component mass during the dispensing process.

[0026] According to a further aspect, a system for storing and dispensing a flowable multi-component compound is provided. The system comprises, on the one hand, a coaxial cartridge of the type described herein and, on the other hand, a support structure with an internally cylindrical receptacle, at least in sections, whose shape and size are designed for inserting and holding the cartridge for dispensing the multi-component compound therefrom.

[0027] A gap in the form of a substantially cylindrical annular gap remains between the inner surface of the support structure receptacle and the outer wall of the cartridge inserted therein, simplifying the insertion of the cartridge into the support structure before the extrusion process. In other words, the inner diameter of the cylindrical support structure receptacle is larger by a predetermined twice the annular gap width than the outer diameter of the cartridge's outer wall when the predetermined expansion points are not expanded. Ideally, the annular gap width is just large enough to allow the cartridge to be inserted smoothly into the support structure receptacle.

[0028] In contrast to conventional coaxial cartridges with a continuously thick, elastically deformable outer wall, this annular gap in the present system does not promote any disruptive restoring or pumping behavior of the cartridge during the dispensing process, because ideally it only serves to expand the outer wall, which is due to a plastic (and thus restoring force-free) deformation in the area of ​​the desired expansion points.

[0029] According to one embodiment of the system, each predetermined expansion point of the cartridge is formed by an external groove in its outer wall; and the support structure has radially inwardly projecting ribs in those areas of the receptacle that correspond to the external grooves of the cartridge inserted in the support structure. Each rib extends axially along the associated groove and, in radial cross-section, only partially projects into the groove (for example, as in Fig. 4), so that the groove (ie the desired expansion point) can expand plastically into a remaining gap towards the rib and / or around the rib during the pressing process and the outer wall of the cartridge is supported by the rib in the area of ​​the desired expansion point during this expansion.

[0030] In particular, the system may also comprise the above-mentioned mixer, which is designed to be connected to a connection piece of the cartridge front wall and to mix the first and second components of the multi-component mass during the squeezing process.

[0031] According to a further aspect, a method for extruding a flowable multi-component mass from the coaxial cartridge of a system of the type described herein is provided. The method comprises the steps: Providing a coaxial cartridge of the type described herein, in whose inner chamber a first component and in whose outer chamber a second component of a multi-component compound are accommodated and whose predetermined expansion points in the outer wall are in a non-expanded state; inserting the cartridge into the receptacle of the support structure provided for this purpose; and pressing the first component out of the inner chamber and the second component out of the outer chamber by simultaneously axially moving the inner and outer pistons towards the cartridge front wall. During this pressing process, the predetermined expansion points plastically expand radially into the annular gap between the cartridge and the support structure until the outer wall of the cartridge thereby at least partially conforms to the inside of the receptacle of the support structure.

[0032] The above aspects of the invention and their embodiments and specific configurations are further explained below with reference to examples illustrated in the drawings. The drawings are schematic. They may, but do not have to, be to scale. They show: Figure 1 shows a longitudinal section of a system of the type described herein with a coaxial cartridge inserted in a support structure with a cylindrical annular gap therebetween; Figure 2 shows a side view on the left and a radial cross section on the right of a coaxial cartridge made of Fig. 1 according to an embodiment with four predetermined expansion points in the form of axial grooves evenly distributed over the circumference of its outer wall; Figure 3 on the left shows a side view and on the right a radial cross section of a coaxial cartridge made of Fig. 1according to a further embodiment with twelve predetermined expansion points in the form of axial grooves evenly distributed over the circumference of its outer wall; and Figure 4 shows a cross section of a system of Fig. 1 with the cartridge Fig. 3 according to an embodiment in which the support structure has axial ribs formed on the inside in the region of the desired expansion points.

[0033] Figure 1 shows, in an axial longitudinal section, an example of a system 1 of the type described herein, in which a coaxial cartridge 2 for extruding the multi-component compound contained therein is inserted into a hollow cylindrical receptacle 13 of a support structure 3. In this example, the coaxial cartridge 2 is made of plastic. The same can also apply to the support structure 3.

[0034] The cartridge 2 comprises a hollow cylindrical inner wall 4 and a hollow cylindrical outer wall 5 arranged around it with a common cylinder axis A, whereby an inner chamber 6 radially delimited by the inner wall 4 and an outer chamber 7 arranged radially between the inner wall 4 and the outer wall 5 are formed. The inner chamber 6 accommodates a first component of the multi-component mass to be dispensed, while the outer chamber 7 accommodates a second component of the multi-component mass (not shown).

[0035] At one in Fig. 1On the right-hand end face of the cartridge 2, its cartridge front wall 8 closes the inner chamber 6 and the outer chamber 7, with one dispensing opening per chamber being formed in the cartridge front wall 8. The two dispensing openings open into a connecting piece 9, which is formed in the cartridge front wall 8 on the side facing away from the inner and outer chambers (6, 7) and is designed for connecting (e.g. by placing or screwing on) a mixer (not shown) for mixing the first and second components of the multi-component mass during the dispensing process.

[0036] Furthermore, the cartridge 2 comprises an inner piston 10 closing the inner chamber 6 at the rear and axially movable therein, and an outer piston 11 closing the outer chamber 7 at the rear and axially movable therein, by their simultaneous axial movement in Fig. 1to the right the multi-component mass can be pressed out of the cartridge 2 through the dispensing openings of the cartridge front wall 8 (pressing process).

[0037] The coaxial cartridge 2 is slightly smaller in diameter than the support structure 3, so that a cylindrical annular gap 12 remains between the outer wall 5 of the cartridge and the cylindrical receptacle 13 of the support structure 3, which facilitates the insertion of the cartridge 5 into the receptacle 13. The cartridge 2 has predetermined expansion points 14 in its outer wall 5 (only in Fig. 2 to 4 shown) in order to experience immediate plastic deformation when pressure is applied and thus to reduce or even completely prevent the pumping behavior during the pressing process.

[0038] Fig. 2 and 3 show two different embodiments of the cartridge 2 from Fig. 1, each in an axial side view (left) and in a radial cross-section (right). The only difference between the two examples is that in Fig. 2 four and in Fig. 3 twelve predetermined expansion points 14 are formed in the outer wall 5, each of which is distributed radially evenly over the circumference of the outer wall 5 of the cartridge 2. The predetermined expansion points 14 have an axial main orientation and, even at low pressures, allow the cartridge 2 to be placed against the support structure 3 ( Fig. 4 ), which significantly reduces the recovery behavior (pumping). Any number of predetermined expansion points 14 in the outer wall 5 can be selected depending on the plastic expansion requirements.

[0039] In this example, the cartridge 2 is cast in one piece, but in the area of ​​the predetermined expansion points 14, the material thickness is reduced in the form of straight grooves on the outside, running parallel to the cylinder axis A and with an approximately rectangular cross-section. The inner diameter of the outer wall 5 remains constant in order to ensure the tightness of the outer piston 11 ( Fig. 1 ). The nominal expansion points 14 are in Fig. 2-4 Each is shown in its non-expanded state, which is prior to a pressing process. The cross-section of cartridge 2 is circular here.

[0040] In order to compensate for an increase in the diameter of the outer wall 5 which occurs when the cartridge 2 is pressurized and which entails the expansion of the predetermined expansion points 14, and to continue to ensure the tightness of the pistons, the pistons are equipped with correspondingly elastic sealing lips (not shown).

[0041] Fig. 4shows a radial cross-section of a system 1 of the Fig. 1 with cartridge 2 Fig. 3 according to an embodiment, with which damage to the predetermined expansion points 14 upon pressure application during the further course of the extrusion process can be reliably avoided. For this purpose, the surrounding support structure 3 in the area of ​​the predetermined expansion points 14 of the cartridge 2 has axial ribs 15, which come into contact with the base of the grooves in the outer wall 5 during the radial expansion of the cartridge 2 and support them. In this way, the cylindrical shape of the cartridge 2 can be maintained when the diameter of the cartridge 2 increases.

Claims

1. Coaxial cartridge (2) for storing a flowable multi-component composition and for insertion into a support structure (3) for dispensing the composition from the cartridge (2), the coaxial cartridge comprising: - a hollow-cylindrical inner wall (4) and a hollow-cylindrical outer wall (5) arranged coaxially around said inner wall, so that the cartridge (2) has an inner chamber (6), which is delimited radially by the inner wall (4), for receiving a first component, and an outer chamber (7), which is arranged radially between the inner wall (4) and the outer wall (5), for receiving a second component of the multi-component composition; - a cartridge front wall (8) which firmly closes the inner and the outer chamber (6, 7) on one end face of the cartridge (2) and has one discharge opening per chamber; and - an inner piston (10) which closes the inner chamber (6) at the rear and is axially movable therein, and an outer piston (11) which closes the outer chamber (7) at the rear and is axially movable therein; - characterized in that one or more predetermined expansion points (14) are formed in the outer wall (5), each of which extend axially from one end face to the other end face of the cartridge (2) and are plastically deformable such that, during the dispensing process, the target expansion points immediately yield to pressure acting on the outer wall (5) from the inside by plastically expanding; and the outer wall (5) is otherwise designed to be dimensionally stable, in particular thick-walled, such that, when the compound is dispensed from the cartridge (2) by axial displacement of the inner and outer pistons (10, 11), the outer wall retains its shape apart from the expansion of the predetermined expansion points (14).

2. Coaxial cartridge (2) according to claim 1, wherein - the plurality of predetermined expansion points (14) are evenly distributed over a circumference of the outer wall (5); and / or - the plurality of predetermined expansion points (14) are identical to one another; and / or - each predetermined expansion point (14) extends in a straight line, in parallel with a cylinder axis (A) of the cartridge (2).

3. Coaxial cartridge (2) according to claim 1 or claim 2, wherein - the outer piston (11) has an elastic sealing lip in its region that is adjacent to the outer wall (5), which sealing lip is designed to be in sealing contact with the outer wall (5) as a result of elastic precompression before and during the entire dispensing process, and to thereby compensate for the increase in diameter of the outer wall when the predetermined expansion points (14) expand.

4. Coaxial cartridge (2) according to any of the preceding claims, wherein - at least one of the predetermined expansion points (14) is designed such that a wall thickness of the outer wall (5) is reduced in the region of the predetermined expansion point (14).

5. Coaxial cartridge (2) according to claim 4, wherein - at least one of the predetermined expansion points (14) is formed by an external groove in the outer wall (5).

6. Coaxial cartridge (2) according to any of the preceding claims, which, - with the exception of the pistons, is made in one piece.

7. Coaxial cartridge (2) according to any of the preceding claims, wherein - the cartridge front wall (8) has, on its side facing away from the inner and the outer chamber (6, 7), a connecting piece (9) into which the discharge openings of the inner and the outer chamber (6, 7) open and which is designed to connect a mixer for mixing the first and second components of the multi-component composition during the dispensing process.

8. System (1) for storing and discharging a flowable multi-component composition, comprising: - a coaxial cartridge (2) according to any of the preceding claims; and - a support structure (3) having a receptacle (13) which is, at least in portions, internally cylindrical, the shape and size of which receptacle is dimensioned for inserting and holding the cartridge (2) in order to dispense the multi-component composition therefrom, - wherein an inner diameter of the cylindrical receptacle (13) of the support structure (3) is greater than an outer diameter of the outer wall (5) of the cartridge (2) by a predetermined double annular gap width when the predetermined expansion points (14) are not expanded, wherein this annular gap (12) between the outer wall (5) of the cartridge (2) and the cylindrical receptacle (13) of the support structure (3) is preferably just wide enough to allow the cartridge (2) to be inserted frictionlessly into the receptacle (13) of the support structure (3).

9. System (1) according to claim 8, wherein - each predetermined expansion point (14) of the cartridge (2) is formed by an external groove in the outer wall (5) of said cartridge; and - the support structure (3) has radially inwardly projecting ribs (15) in the regions of the receptacle (13) that correspond to the external grooves of a cartridge (2) inserted in the support structure (3), wherein each rib (15) extends axially along the associated groove and projects only partially into the groove in radial cross section, so that the groove can expand plastically into a remaining space, toward the rib (15) and / or around the rib (15), during the dispensing process, and the outer wall (5) of the cartridge (2) is supported by the rib (15) in the region of the relevant predetermined expansion point (14) during this expansion.

10. Method for dispensing a flowable multi-component composition from the coaxial cartridge (2) of a system (1) according to claim 8 or claim 9, comprising the steps of: - providing a coaxial cartridge (2) according to any of claims 1 to 7, in the inner chamber (6) of which a first component of a multi-component composition is received, and in the outer chamber (7) of which a second component of a multi-component composition is received, and the predetermined expansion points (14) of which cartridge, in the outer wall (5), are in a non-expanded state; - inserting the cartridge (2) into the receptacle (13) of the support structure (3) provided for this purpose; and - dispensing the first component from the inner chamber (6) and the second component from the outer chamber (7) by a simultaneous axial movement of the inner piston (10) and the outer piston (11) toward the cartridge front wall (8); - so that, during this dispensing process, the predetermined expansion points (14) plastically expand radially into the above-mentioned annular gap (12) between the outer wall (5) of the cartridge (2) and the cylindrical receptacle (13) of the support structure (3) until the outer wall (5) at least partially conforms to the inside of the receptacle (13) of the support structure (3) as a result.