WO2009052995A1 - Method of producing a two-chamber pressure vessel - Google Patents

Abstract

In the case of an apparatus for producing a two-chamber pressure vessel made of an outer vessel (1) and a deformable inner vessel (5) for accommodating a product, the outer vessel (1) is intended to have material accumulations in certain parts.

Description

 Method for producing a two-chamber pressure vessel

The invention relates to a method for producing a two-chamber pressure vessel from an outer container and a deformable inner container for receiving a product.

PRIOR ART Such two-chamber pressure vessels are known in a variety of forms and designs and are on the market. They are described, for example, in EP-A 0 326 052 or DE 44 13 331 A1.

Due to the different wall thickness of inner container and outer container and a different stress or filling and optionally by different materials or material compositions, inner container and outer container are subject to different thermal expansion. However, more serious is the fact that through the different thermal expansion of propellant in the outer container and filling material in the inner body, the material of the inner body begins to breathe. Since, however, the side of the inner wall of the outer container rests smoothly, it can only escape downwards into the interior space filled with compressed gas, which leads to transverse breaks of the inner container. The inner container initially adapts to the geometry of the outer container after filling. After the subsequent filling of the outer container with propellant and by the thermal cycling of the inner body begins to breathe. The result is first a longitudinal fold, then a transverse fold, which crosses the longitudinal fold. After approx. 20 - 30 respiratory cycles a break, a so-called pinhole, develops at the crossing point of both wrinkles.

This was an attempt to counteract that wrinkles were formed in the inner container, as described in EP 1 813 548 A1, EP 1 813 549 A1 and EP 1 813 550 A1. Although this increased the elasticity of the inner body in the short term, in the long term this meant, on the one hand, more use of material and, on the other hand, a different attack surface for the pressurized gas. This, in turn, caused the fractures of the inner body to easily break.

Another disadvantage of known two-chamber pressure packs is the fact that the longer these two-chamber cans are designed, the more likely they are to assume a banana shape.

TASK

The present invention has for its object to provide a device of the type mentioned above, which ensures greater stability and strength and barely increases the cost of production and controls the wrinkling of the inner container so that the inner container withstand at least twice as many cycles of thermal cycling. SOLUTION OF THE TASK

To achieve this object, that the outer container has partial material accumulations.

The outer container is a cylinder and is preferred, but not made of aluminum. It is used e.g. also tinplate. The inner container is made of all suitable materials, but especially of aluminum

The outer surface of the outer container is preferably designed smooth and is therefore particularly well suited for imprints. In addition, a smooth outer surface also offers advantages in transport, as each can takes up less space and it can not lead to wedges, which could not be excluded if the outer container on the outside material accumulations would have. This would only be useful anyway, if only thought to improve the rigidity of the container. For this reason, the invention relates primarily to material accumulations on the inner surface of the outer container. Material accumulations on the outside of the container should, however, be included in the present invention.

These accumulations of material are preferably in the form of ribs. The ribs extend in a raised manner along the inside of the outer container. They run at the same distance axially parallel to each other. They serve to give the outer container an improved rigidity, but above all to support the inner container. The ribs support the inner container by forming common contact surfaces with it. They form between themselves an additional space for the inner container, if this, for whatever reason, should extend more than the outer container. This strong expansion can occur, for example, with temperature changes. In addition, they fulfill the task that the pressurized gas can flow much laterally much more uniformly on the inner container and can be detached from the inner surface of the outer container.

The higher rigidity also has directly and indirectly different positive effects. First of all, as mentioned above, in dual-chamber pressure packs, it is often observed that they take on a banana shape with a longer design. However, this deformation is prevented by the ribs, without it being necessary to make the outer walls thicker. This has several advantages indirectly. Thus, the ribs require less material and energy input during production. A further advantage is the fact that the capacity of the inner container is not changed by the ribs. Different, if outer walls are used with greater thickness. Then the inner container would have to be reduced in size with the same total diameter.

The fact that the ribs are axially parallel, an optimal distribution for the desired stiffness is achieved. A different division would only result in three ribs that creates an imbalance of power and the can, similar to a bimetal, again accept the banana shape in pressure and / or temperature differences.

Three ribs are the preferred design, but it is quite possible to use more or even less than three ribs. Especially in Außenbehältem with very large diameters, it may also be advantageous in individual cases that more than three ribs are used.

The outer container is produced, for example, by extrusion. When extrusion is pressed with high pressure and high speed, the Ronde to be processed in a mold having corresponding grooves or grooves. This procedure results in the production of the outer container, that the ribs are continuous to the upper end of the Exterior container extend. The upper portion of the outer container must be free of these ribs and have a smooth shape. This follows from the fact that in the upper area of the inner container is connected to the outer container. With a non-smooth surface, the gas-tight connection of the two containers is difficult or impossible.

For further processing, the ribs must therefore be removed again in the upper area of the outer container. This is preferably done but not conclusive by milling. When milling, for example, the ribs in the upper area of the outer container are removed to a length of approx. 25 mm by machining. This is preferably done down to the level of the inner wall.

figure description

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawing; this shows in

1 shows a longitudinal section through a container according to the invention;

Figure 2 shows a cross section through the container according to Figure 1 along line H-II.

According to FIG. 1, a two-chamber container according to the invention consists of an outer container 1 and an inner container 5. The outer container 1 has a cylindrical outer surface 3, which is smooth. This should only be considered as a preferred embodiment and exclude other types of external surfaces. Just to achieve a better grip, the outer surface, similar to drinking bottles in recent years become common, be designed in a special way.

The outer container 1 has on its inner surface 2 at least one rib 4. Preferably, it has a total of three ribs in each case the same distance. The rib 4 serves to give the outer container 1 a certain stiffness, but above all to support the inner container 5. The rib 4 is in the illustrated embodiment part of a wall 6 of the outer container 1. However, this is only the preferred embodiment. Also to be covered by this are also introduced deposits or essays in the form of ribs 4, which are not integral part of the wall 6. To emphasize here is more the function of the ribs 4 described later.

In FIG. 1, the rib 4 has contact surfaces 7 with the inner container 5. In the embodiment shown, this surface is actually in contact. However, embodiments are also to be considered in which the rib 4 has only some contact surfaces with the inner container 5. Furthermore, exemplary embodiments thereof are to be covered, in which the inner container 5 in addition to the rib 4 also partially contact surfaces with the inner surface 2 of the outer container 1 has.

Figure 2 shows in which form the three ribs 4 are attached to the inside 2 of the outer container 1. They are distributed in such a way that in each case between each rib 4 to the next rib 4 are 120 °. This is only a preferred embodiment. The ribs 4 are on this

Optimally distributed and thus can best fulfill their task.

However, the ribs can also be distributed in a different arrangement. It is conceivable that arises on one side of the outer container 1 due to the use of more pressure. Then it is also conceivable that two of the ribs have a smaller distance than 120 ° from each other.

The function of the ribs 4, in addition to improving the rigidity of the outer container 1, the support of the inner container 5. If the container exposed to heat, it comes to different thermal expansion between outer container 1 and inner container 5, but especially between the propellant, which is in Outer container 1 is located and the contents that is located in the inner container 5. This happens as a result of different thermal expansion coefficients. This in turn, it can, since the inner container 5 has in commercial outer containers only down space, come to cross breaks. The ribs also allow the inner container 5 to extend laterally into the spaces formed by them.

DR. PETER WEISS & ARAT

Patent Attorneys European Patent Attorney

Reference: P 3764 / PCZ Date: 07.09.2007 DA / DA

LIST OF REFERENCE NUMBERS

Claims

claims 1. A device for producing a two-chamber pressure vessel from an outer container (1) and a deformable inner container (5) for receiving a product, characterized, the outer container (1) has partial accumulations of material. 2. Device according to claim 1, characterized in that an outer surface (3) of the outer container (1) is cylindrical and has a smooth surface. 3. Apparatus according to claim 1 or 2, characterized in that the accumulations of material in the form of at least one rib (4) raised along an inner surface (2) of the outer container (1) extend. 4. Apparatus according to claim 3, characterized in that a plurality of ribs (4) on the inner surface (2) of the outer container (1) extend parallel to the axis. 5. The device according to at least one of claims 3 or 4, characterized in that three ribs (4) in each case the same distance from each other axially parallel along the inner surface (2) of the outer container (1). 6. Device according to at least one of claims 1 to 5, characterized in that the material accumulations in the upper region of the outer container (1) are removed. 7. Apparatus according to claim 6, characterized in that the ribs (4) are removed in the connecting region of inner container (5) and outer container (1). 8. The device according to at least one of claims 1 - to 7, characterized in that the inner container (5) with the ribs (4) has common contact surfaces (7). 9. A method for producing a two-chamber pressure vessel from an outer container (1) and a deformable inner container (5) for receiving a product, characterized in that the outer container (1) is provided during or after its production with partial material accumulations (4). 10. The method according to claim 9, characterized in that the material for the outer container (1) is partially introduced into grooves in a mold. 11. The method according to claim 9 or 10, characterized in that the accumulation of material in the connecting region between the inner container (5) and outer container (1) is removed.