Pressure Can with Modified Riser Tube

The present invention relates to a pressure can for dispensing spray agents.

Pressure cans, for example aerosol can pressure cans, are regularly used for dispensing a spray agent, which can be filled into the container of this pressure can as a filling material together with a propellant and then dispensed via a valve. The use of riser tubes is known in this context, in particular to improve the spray pattern and to enable the spray agent to flow as evenly as possible to the valve.

The riser pipe extends from the valve intended for dispensing the spray agent into the container of the pressure can. By actuating the valve to dispense the spray agent, the spray agent is transported from the inside of the container to the valve with the aid of the riser tube and dispensed through the valve, e.g. sprayed onto a surface to be coated.

Such spray cans can be used to produce a homogeneous spray pattern, whereby the more intensively the propellant is mixed with the spray agent, the better the quality of the spray pattern. For this purpose, mechanical mixing by shaking the spray cans is common. In some cases, attempts are made to intensify the movement by using mixing balls inside the can, which in turn can reduce agglomerates or droplets through the movement.

This need for mechanical movement to homogenize the sprayed aerosol is all the more important the lower the fill level in the can.

If we look at the typical change in a spray pattern over a longer period of time from this perspective, it is easy to explain the reduction in quality: On the one hand, over the course of time, the homogenization due to shaking lags behind longer and longer, so that droplets and/or agglomerates are already forming again; on the other hand, the fill level in the can decreases, which also promotes droplet and/or agglomerate formation. The formation of layers of different densities within the pressure can over time is also referred to as the formation of a gradient. This means that the heavier, pigment- and propellant-rich components sink in the direction of gravity and the lighter components accumulate above them. This lowering can lead to the formation of a layer rich in solids, particularly in the central area of the can during a prolonged application. As the material is transported from this lower area of the can during application, this can result in severe impairment of the spray pattern, including so-called spitting. The user will perceive this as a deterioration in the spray performance and will not continue to use the can. The unused portion of can contents is therefore a residue that increases the resulting waste. It is therefore essential to maintain as uniform an aerosol formation as possible over as long a period as possible.

In practice, it is therefore often the case that the consumer does not use the entire contents of the can, as this requires a prolonged period of mechanical agitation in the form of shaking when the fill level is low, which either does not last long enough or does not take place at all after initial use.

To make matters worse, the time required can hardly be estimated, as it also depends on the intensity of the movements in terms of amplitude, the force applied and other factors.

The task of the present invention is therefore to provide a pressure can in which a greater variance in the use of the can in terms of mechanical mixing can be tolerated without negatively affecting the output of the aerosol. This concerns both a more constant spray pattern and the ecologically significant aspect of complete utilization of the can contents. Furthermore, the task of the present invention is to ensure improved emptying of the pressure can while maintaining a high-quality spray pattern

The task is solved with the features of a pressure can according to claim.

Accordingly, the pressure can for dispensing a spray agent comprises a container, a valve and a riser pipe. The container serves to hold the spray agent and has a container wall and a curved container base, i.e. a base which projects into an inner filling volume of the container formed by the container wall. The container can have an essentially cylindrical shape, with the container base and the container wall being connected to each other by flanging. Furthermore, the container wall can also comprise a dome, which is also connected to the container wall opposite the container base via flanging. The valve can be arranged on the side of the container opposite the container base and close the container wall here. The valve can, for example, be connected to the dome.

As soon as the pressure can according to the invention is filled with a spray agent and closed, the spray agent can be dispensed by actuating the valve. For this purpose, a spray head can be placed on the valve, whereby the valve is actuated with the aid of the spray head, e.g. by pressing on the spray head, the valve opens and the pressurized spray agent is dispensed.

The pressurized can also has the riser pipe, which extends from the valve to the base of the container. The riser pipe has a lateral surface and two openings arranged at each end of the riser pipe. The riser pipe can therefore have the shape of a hollow cylinder, for example. The riser tube is not necessarily to be understood as an inflexible tube but can also be designed as a type of hose. Furthermore, the riser tube can also deviate from the shape of a hollow cylinder and, for example, be beveled or chamfered in the area of the container-side riser tube opening.

The riser pipe is connected to the valve via one of the riser pipe openings. This opening is therefore arranged on a first end face of the riser pipe and forms a valve-side riser pipe opening. The other riser pipe opening of the riser pipe, which is arranged on a second end face of the riser pipe, protrudes into the container and thus forms a container-side riser pipe opening. The container-side riser pipe opening can project into the filling volume formed by the container, whereby the riser pipe is set up to guide the spray agent from the container-side riser pipe opening to the valve-side riser pipe opening. In other words, a pressurized spray agent can be guided through the container-side riser pipe opening to the valve-side riser pipe opening by corresponding actuation of the valve and leave the valve here, for example through the spray head.

The riser pipe also extends from the valve closer to the bottom of the container than to the center of the container. Here, the container center point defines a point within the container that is centrally located with respect to an extension of the container in the longitudinal direction, i.e. a point that is centrally located with respect to a distance in the longitudinal direction between the valve and the container base. In other words, the container center point defines a point within the container that is centrally located with respect to a longitudinal extension of the container that runs parallel to the container wall, wherein the riser tube is longer than a distance measured from the valve to this point, i.e., to the container center point. More precisely, the riser pipe extends from the valve closer to the bottom of the container than to the center of the container.

Consequently, the container-side riser pipe opening of the riser pipe is arranged closer to the container base than to the container center. In other words, the distance between the container-side riser pipe opening and the container base is smaller than the distance to the container center. Preferably, the riser tube is designed such that the riser tube protrudes into this spray sump when a spray sump is formed, as described above, at the container base, i.e. when spray is deposited at the container base, for example due to storage of the pressure can.

In addition to the container-side riser tube opening, the riser tube also has at least one further opening, which is designed to enlarge a container-side opening cross-section of the riser tube independently of a filling volume of the pressure can. In other words, the at least one additional opening is designed to enlarge the opening cross-section of the riser tube on the container side, which without the at least one additional opening would only ever be formed by the riser tube opening on the container side formed on the second end face of the riser tube. Consequently, the at least one additional opening can increase the opening cross-section of the riser pipe compared to a riser pipe provided only with a container-side riser pipe opening.

The container-side opening cross-section of the riser tube can thus be formed not only by an opening cross-section of the container-side riser tube opening, but also by an enlarged opening cross-section which is formed from the opening cross-section of the riser tube as the opening of the hollow cylinder forming the riser tube and the at least one additional opening. In other words, the opening according to the invention can not only be an opening in the wall of the riser tube, but can also be designed as an extension of the opening cross-section.

In this context, the possibility of enlarging the opening cross-section of the riser tube on the container side is independent of the filling volume of the pressure can. Therefore, the opening cross-section of the riser tube on the container side can be enlarged due to the at least one additional opening, both with a completely filled pressure can and with a pressure can that is only half full, quarter full or otherwise full.

The increase in the opening cross-section can be fixed. Preferably, however, the enlargement of the opening cross-section can be changed. For example, the opening cross-section of the riser pipe on the container side can be variable in such a way that, in the case of a pressurized can containing a pressurized spray agent, it increases due to actuation of the valve, for example due to the resulting flow of the spray agent from the container through the riser pipe to the valve, and decreases again after actuation of the valve. The increase in the opening cross-section can also be variable depending on the pressurized spray agent. However, the opening cross-section of the riser pipe on the container side can also be unchangeable, i.e. its size can be the same regardless of whether the valve is actuated, for example.

In summary, the opening cross-section of the riser tube on the container side can be a sum of the opening cross-section of the riser tube opening on the container side and the opening cross-section of the at least one additional opening. However, alternatively or in addition to this, the at least one additional opening in a pressurized can filled with a pressurized spray agent can also only form and/or enlarge when the valve is actuated.

The at least one additional opening is formed by an incision. The incision can be arranged in some areas of the lateral surface and in some areas of the second end face of the riser tube. Consequently, the at least one additional opening can also be formed by a separation of the lateral surface of the riser tube, i.e. by an incision. The specific type of design of the at least one additional opening also offers advantages in production in addition to the improved application of the spray agent.

The enlargement of the opening cross-section on the container side ensures that the pressure can be emptied as complete as possible even with less shaking by the person using the pressure can. Depending on the specific design of the riser tube, the riser tube can even protrude into the spray agent sump without sticking or clogging, thus enabling the continuous functionality of the pressure can. Tests have shown that between 5% and 10% more spray agent can be dispensed from a pressure can with the aid of the solution according to the invention. At the same time, it was surprisingly found that the design of the riser tube according to the invention also means that the volume of spray agent dispensed remains more constant over the course of the filling level of the pressure can, thus enabling an improved spray pattern. It should also be noted that the modifications made to the riser tube are only minimal and do not require any additional components or complex manufacturing steps. Consequently, the design of the riser tube of a pressure can according to the invention not only improves the function of the pressure can, but also creates an improvement that is worthwhile from an economic point of view.

According to another embodiment, the at least one additional opening can be arranged in the lateral surface of the riser tube. In other words, the riser tube then comprises at least one additional opening, which is arranged in the lateral surface of the riser tube, and a container-side riser tube opening, which is arranged in the second end face of the riser tube. Together, the openings, i.e. the at least one additional opening and the container-side riser tube opening, form the container-side opening cross-section of the riser tube and enable optimized application of the spray agent. Depending on the design of the riser tube, it can be advantageous if the opening cross-section of the at least one additional opening is arranged essentially at right angles to the opening cross-section of the container-side riser tube opening arranged in the second end face of the riser tube. It can also be advantageous if the at least one additional opening is arranged on the lateral surface of the riser tube in such a way that the at least one additional opening in a filled pressurized can is arranged in some areas above a sump of spray agent that forms during storage. The container-side riser tube opening, which is arranged on the second end face of the riser tube, is immersed in a maximum spray sump. A “maximum spray sump” is defined by the maximum amount of spray deposited at the bottom of the container, which would occur if the pressure can were stored in a completely filled state. The specific design of the pressure can, whereby the at least one additional opening is arranged on the outer surface of the riser tube, can therefore increase the container-side opening cross-section independently of the filling volume of the pressure can, although in this design this is achieved by two openings that are separated from each other.

According to a further embodiment, the at least one additional opening can be arranged at least partially in the lateral surface and the second end face of the riser tube. In other words, the at least one additional opening is not only arranged completely in the lateral surface of the riser tube, but also extends into the second end face of the riser tube. An opening cross-section of the container-side riser tube opening can merge seamlessly into an opening cross-section of the at least one additional opening. This means that the two opening cross-sections can merge into one another and together form an enlarged opening cross-section. The arrangement of the at least one additional opening in the area of the second end face of the riser tube not only improves the discharge of the spray agent, but also allows easy accessibility so that the at least one additional opening can be inserted precisely into the riser tube.

When the valve of the pressure can is actuated with a pressurized spray agent, the spray agent flow can widen the incision, whereby the opening cross-section of the riser tube on the container side can be enlarged. The at least one additional opening can only become clearly visible when a spray agent is applied due to the widening. However, the riser pipe can also widen independently of valve actuation due to the incision alone. The at least one additional opening, i.e. the incision, can then widen further when the valve of the pressure can is actuated.

According to a further embodiment, the riser tube can have at least two additional openings. Preferably, two of the at least two additional openings are arranged diametrically opposite each other, at least in some areas. In other words, the riser tube may, for example, have two diametrically opposite incisions, each of the incisions being arranged at least in certain regions in the lateral surface and the second end face of the riser tube. Preferably, the riser tube has exactly two additional openings. However, the riser tube can also have, for example, only one additional opening, three additional openings or four additional openings. A different number of additional openings is also possible. Tests have shown that an optimum ratio between spray rate and residual emptying can be achieved if exactly two diametrically opposed incisions are used. It was also found that the residual emptying can be greater with only one incision in the riser pipe. However, a greater invariance of the spraying rate over time was determined at the same time.

According to a further aspect, the riser pipe can have more than at least two additional openings, as previously mentioned. In this case, it is preferred if an angle between two adjacent additional openings measured in the circumferential direction of the riser tube is at least 90°. For example, the riser tube can have three additional openings, each of which is arranged at least partially in the lateral surface and the second end face of the riser tube, and wherein the angle between two adjacent incisions is 120° each. The riser tube can also have, for example, four incisions, each of which is offset by 90° in the circumferential direction of the riser tube. A sufficient distance between adjacent incisions can favor the expansion of the riser tube and thus lead to an improved application of the spray agent.

According to a further aspect of the invention, the at least one additional opening can extend along the riser tube from the container-side riser tube opening to the valve-side riser tube opening over a length of less than 40 mm, preferably over a length of between 5 mm and 30 mm, most preferably over a length of 15 mm. In the case of a circular opening, the length of the at least one additional opening would therefore correspond to the diameter of the additional opening. The at least one additional opening in the form of an incision can, for example, extend from the second end face of the riser pipe in the direction of the valve-side riser pipe opening. This means, for example, that the riser pipe can be cut longitudinally at the container-side riser pipe opening. An additional opening on the riser tube designed in accordance with the length specifications further optimizes the application of the spray agent.

According to one embodiment, the length of the at least one additional opening can have a ratio of at least 1 to 33 to the total length of the riser tube. Preferably, the ratio is at most 1 to 5. Preferably, the ratio is between 1 to 10 and 1 to 11. With a highly preferred length of the at least one additional opening of 15 mm and a preferred ratio of between 1 to 10 and 1 to 11, this would mean that the total length of the riser tube is between 150 mm and 165 mm. It can thus be established that the length of the at least one additional opening is relatively small in relation to the overall length of the riser tube and yet has a decisive effect on the improved spray agent application.

According to a further embodiment of the present invention, the riser tube may have an overall length of between 145 mm and 170 mm. Preferably, the riser tube has an overall length of 155 mm. The total length of the riser tube is defined by a shortest path measured along the lateral surface of the riser tube between the first end face and the second end face. Furthermore, the riser tube can have an outer diameter of between 1 mm and 7 mm, preferably between 3 mm and 6 mm. Very preferably, the riser tube has an outer diameter of 4 mm.

Preferably, the aforementioned length ratios and dimensions, i.e. the total length of the riser tube, the outer diameter of the riser tube and the length of the at least one additional opening, relate to dimensions for a pressure can with a nominal filling volume of 400 ml. According to one aspect, however, the invention can also be used for pressure cans with a filling volume of from 50 ml to 1000 ml, preferably from 150 ml to 600 ml. Preferably, a necked-in or straight 400 ml pressure can is used. According to one aspect of the invention, the pressure can can have a nominal filling volume according to EN 15007:2006 (D).

In a further embodiment, the riser tube can be formed from a material that is flexible at least in some areas. Preferably, the riser tube can be made of an elastic, flexible material such as polypropylene or polyethylene. As a result, the container-side riser tube opening fans out or expands particularly easily during the application of a spray agent. This means that the at least one additional riser pipe opening can expand, for example when the spray agent is dispensed, whereby a type of funnel can be formed on the riser pipe in the area of the second end face due to the expansion. However, the riser tube can also widen or fan out simply by introducing an additional opening, for example a cut, independently of the application of the spray agent. In one arrangement, for example, two additional openings can be arranged opposite each other. For example, the riser pipe can be cut at opposite points. An opposing arrangement of at least two additional openings, on the other hand, can favor a symmetrical fanning out of the container-side riser tube opening. For example, the lateral surface segments of the riser tube, which are separated in some areas by the two incisions, can fold outwards when the valve of the pressure can is actuated. The extent or degree of fanning out of the at least one additional opening can be continuously reduced due to the pressure drop within the can during dispensing, whereby the riser tube initially fanned out in the area of the container-side riser tube opening can gradually contract as the spray agent is continuously dispensed. By fanning out the riser tube, both the spray pattern can be improved and the emptying of the pressure can optimized.

According to one embodiment, the riser tube can have at least one round opening arranged in the lateral surface of the riser tube. According to one aspect, the round opening can improve the output of the spray agent. This means that the output, which is improved, for example, by fanning out the riser tube during the output of a material and by the resulting enlargement of the opening cross-section of the riser tube on the container side, since this prevents blockage of the riser tube even when the riser tube is immersed in the spray agent sump and at the same time ensures output of the spray agent, can be additionally optimized by the round opening.

Furthermore, in one embodiment, the round opening can be arranged between 1.5 cm and 2 cm above an apex of the curved container base. The apex defines a point on the container base that is the smallest distance from the valve. In one embodiment, the curved container base of the pressure box can form a kind of dome. In the cross-section of the pressure can, the container base can thus essentially have the shape of a semi-ellipse in some areas, with the apex of the container base being the point of the container base that is closest to the center of the container. The relative arrangement of the round opening on the lateral surface of the riser tube allows the riser tube to protrude with the container-side riser tube opening in a spray agent sump, whereby the at least one additional opening can be arranged above this spray agent sump. Consequently, for example, an aerosol which is located above the spray agent sump can be sucked into the riser tube through the at least one additional opening, whereby due to the suction effect created by this, spray agent from the spray agent sump can be sucked into the riser tube with the aid of the container-side riser tube opening, drawn along and discharged from the valve. This ensures a more complete emptying of the pressure can. However, a round opening can also be arranged at the valve-side end of the riser tube and/or designed in such a way that its effect on the discharge of the spray agent is barely detectable.

In a further embodiment, the pressure can can be filled with a propellant and filling material. The propellant can be present in liquid and/or gaseous form. Furthermore, the filling material can comprise at least one paint binder, preferably a hardenable paint binder. In addition, the filling material may comprise a solvent, for example. When the valve is actuated, the propellant can thus, for example, guide the paint binder via the riser pipe to the valve and dispense it here, for example via a spray head. In other words, the spray agent can be formed at least by the propellant and the filling material.

Furthermore, according to one embodiment, the filling material in the pressure can can consist of binders and/or pigments and/or solvents, for example water. Such filling materials are also referred to as spray paints. Water-based paints also use water as a solvent. Preferably, the filling material has a viscosity of 20 to 50 seconds in the 3 mm outlet cup measured at 20° C. room temperature when the pressure can is filled. The use of paint or varnish with a higher solids content and of varnish with a higher density as filling material enables particularly good utilization of the advantages of the invention. According to an alternative or complementary aspect of the invention, the filling material has a solids content of between 15% and 60%, preferably of between 20% and 50%, most preferably of between 25% and 35%. According to a further alternative or complementary aspect of the invention, the filling material has a density of between 0.8 g/l and 3 g/l. The riser tube according to the invention thus enables in particular the use of filling material with a comparatively high density.

According to a further aspect of the present invention, the container wall and the container base can together form a fold. The fold can thereby define the location on the container base at which the container wall and the container base are clinched or clinched. Furthermore, the container-side riser pipe opening can be arranged in an area between the fold and the apex of the container base. The purpose of this is that the riser pipe or the riser pipe opening on the container side can dip into the spray agent sump even with a slight formation of a spray agent sump, which forms at the lowest point of the container and thus in the area of the fold. Consequently, this can also further optimize the output of the spray agent and achieve a more complete emptying of the pressure can. According to a preferred aspect of the invention, the riser tube extends up to the seam. Very preferably, the second end face of the riser tube touches the fold in some areas.

In a further embodiment, a 2-component system, in particular a 2-component system for 2-component sealing foams, 2-component adhesives or 2-component paints, can be arranged at least partially within the container. The 2K component system can comprise an inner sleeve with a release mechanism. Furthermore, the release mechanism can be designed to permanently open the inner sleeve towards the container. This means that the inner sleeve can be opened in such a way that a component contained in the inner sleeve expands into the interior of the container after the inner sleeve has been opened. Consequently, the 2K component system can, for example, be set up to form a multi-component product, for example a multi-component paint, together with a spray agent already contained in the pressurized can when the trigger mechanism is activated, whereby the spray agent reacts with the component of the 2K component system to form a finished end product when the trigger mechanism is activated. After the reaction, the spray agent, i.e. the multi-component spray agent, can also be dispensed via the riser pipe and the valve. The component present in the inner sleeve for the reaction, which reacts with the spraying agent, can have a relatively small quantity compared to the spraying agent. The component present in the inner sleeve can, for example, influence the curing and the quality of the spray agent, e.g. accelerate the curing and/or increase the strength. The reaction initiated by the trigger mechanism can in particular lead to a faster formation of a spray agent sump, which is why the present invention optimizes 2-component systems in particular. In other words, the reacted spray agent of a 2-component system has a particularly high tendency to settle at the bottom of the container, i.e. to form a sump, which is why the solution according to the invention is particularly suitable for pressure cans with a 2-component system.

According to a further aspect of the present invention, the inner sleeve can be arranged on a plate, in particular a base plate, and as part of the release mechanism comprise a plunger arranged in the inner sleeve for bursting open the inner sleeve. In addition, the plunger can be actuated through the plate, whereby the inner sleeve is connected to the plate via a spring cage. Furthermore, the spring cage can contain a resiliently mounted trigger, the end of which on the container base side is guided through the plate and which acts on the plunger. The plunger can also act against a diaphragm arranged at the valve-side end of the inner sleeve, whereby the diaphragm can hermetically seal the inner sleeve at its valve-side end against the contents of the pressure can. When the trigger is actuated by the plunger, the diaphragm can be torn open. In addition, the spring cage can be closed on the valve side and the trigger can be provided with a sealing element on the base side that acts against the inner wall of the spring cage. Such a release mechanism is known, for example, from EP 2 114 795 A1. By arranging the inner sleeve on a plate, the component stored inside the inner sleeve can in particular be discharged above the apex of the container base, so that a reaction preferably takes place above the container-side riser tube opening.

In particular, the arrangement of the 2-component system at the bottom of the container and inside the container reduces the container volume and the floor area available for depositing the spray agent. In addition, the amount of spray agent increases after the 2-component system is triggered, which typically causes an increased amount of spray agent to accumulate or settle at the bottom of the container. Due to the reaction between the filling product and the component of the 2-component system, the spray agent also has a greater tendency to stick to the riser tube or the container-side riser tube opening. Consequently, the embodiment according to the invention is particularly suitable and advantageous for pressure cans with a 2-component system.

Accordingly, the pressure can according to the aspects of the preceding description can also be used for liquid 2-component systems, in particular 2-component sealing foams, 2-component adhesives or 2-component paints. The pressure can can be designed in such a way that the pressure can can be used with or without an actuating aid. When using the pressure can with an actuation aid, the actuation aid can be placed on the pressure can in particular. The actuating aid can serve as a spraying aid, which can only cause the pressure can to be actuated and/or the spray mist to be directed, but not that the spraying agent emerging from the pressure can is conveyed, for example by air pressure. Such transportation of material, as is known, for example, from the use of HVLP spray guns, is not necessary in the present case, since the pressure can typically has a propellant. In other words, the pressure can can be used with a pure actuation aid, which serves solely to actuate the spray head without influencing the atomization or the spray pattern.

In the following, identical elements and components as well as identical elements and components in different examples or embodiments, i.e. elements and components which act identically or are intended for the same purposes but belong to different examples, are provided with the same reference signs in the figures.

shows a riser tubewhich can be used in a pressure can, for example in the pressure canshown in. Although, as described below, the pressure boxincomprises a 2-component system, this is not absolutely necessary for the invention. The riser pipeinhas a first end facewith a valve-side riser pipe opening. The valve-side riser pipe openingcan be connected to a valve, as shown in, for example. On the side of the riser pipeopposite the first end face, i.e. on a second end faceof the riser pipe, the riser pipehas a container-side riser pipe opening.

Between the two end facesandof the riser pipe, the riser pipeis formed by its lateral surfaceand extends with an overall length L. In the area of the second end face, the riser pipealso has an additional opening in the form of a cut. The cutextends from the lateral surfaceinto the container-side opening. The cutshown here thus extends over a length Las far as the second end faceof the riser pipe. A transition between the opening cross-sections of the cutand the container-side riser pipe openingis thus seamless. In addition, the riser pipein the shape shown is essentially in the form of a hollow cylinder.

As soon as the valveof the pressure canis actuated, a spray agentcan flow into the riser tubethrough the container-side riser tube openingand the incision, which fans out or widens, for example. In this case, the cut edges forming the incision, as shown here, can be in contact before a spray agent is dispensed. Due to the pressurized spray agentand the weakening of the material due to the incision, the riser tubethen expands in the area of the container-side riser tube opening, i.e. the riser tubeor the container-side riser tube openingand the incisionare expanded during the application of the spray agent.

According to one aspect, the incision can also be widened simply by inserting the incision. In other words, after the insertion of the incision, the riser pipecan already be widened and then, for example, additionally widen during the application of the spray agent. Irrespective of this, the riser pipethen directs the spray agenttowards the valve-side riser pipe opening.

In an alternative embodiment of a riser pipeshown in, the riser pipehas two additional openings, both of which are in the form of an incisionand arranged diametrically opposite one another. As shown by the dashed arrows, this allows the container-side riser tube openingto fan out very widely during the application of the spray agent.

The opposing incisionscan be made simultaneously in the second end faceof the riser tubein a single manufacturing step. An exemplary top view of a second end faceof a corresponding riser tubeis shown, for example, in.

Although the incisionsare shown in the form of gaps in, these are merely made, for example, by a cutting tool in the second end faceof the riser tubeand the cut edges formed in this way can also touch each other or at least substantially abut each other. The representation as a gap is therefore merely for improved visualization.