EP3183189B1 - Container base and method for production same - Google Patents

Description

FIELD OF THE INVENTION

The present invention relates to a container bottom and a method for its production.

BACKGROUND OF THE INVENTION

Different tank bottoms are known in tank and apparatus construction and in tank construction. Container bottoms are usually curved sheet metal elements which serve to close the ends of a generally cylindrical container or to divide it into several chambers.

The containers themselves are usually cylindrical in shape and have different cross-sections (for example circular, elliptical, two-shell, four-shell, case-shaped). The container jacket is formed from one or more curved sheet metal elements (manufactured in a rolling process) and has a tubular shape with a corresponding cross-sectional geometry. The ends of such a jacket shot are closed with appropriate container bottoms. The container bottoms are usually welded to the jacket section for this purpose. For this purpose, the container base has a connection contour corresponding to the jacket section, so that the jacket and base meet at their respective connection contours and can be connected to one another via a butt weld that is advantageous in terms of production and strength. There are also connection configurations in which the bottom of the container is inserted or plugged into the jacket section and the connection between the two elements is made via a fillet weld. In addition to cylindrical container sections, there are also frustoconical designs.

The container bottoms generally have a cylindrical or conical rim or rim that merges over a relatively narrowly curved (toroidally curved) brim area into a flat - usually spherical - domed spherical cap area, which forms the predominant surface area of the actual floor.

In the case of containers with a circular cross-section, so-called toroidal bottoms are usually used, which have a dished bottom shape according to DIN 28011, a basket arch bottom shape according to DIN 28013 or are designed as an elliptical bottom or as a normal / flat-arched bottom.

Such floors are usually produced in a two-stage process, in which - starting from a flat sheet metal disc (round plate or blank) - the spherical curvature is first formed in a pressing process (pummeling) and then the brim area and the so-called shelf in a pressing process (flanging ) is molded on. In the case of thin-walled floors, these can also be produced entirely in a pressing process (usually a deep-drawing process).

The production of such curved floors for non-circular tank cross sections is particularly demanding. Such floors are from, for example DE 200 05 521 U known. Different utilization ranges for so-called silo containers that connect to non-circular tank cross-sections are, for example US 6,059,372 and the US 6,401,983 B1 known. Such areas can be made of glass fiber reinforced plastics. On the one hand, one cannot fall back on the largely mechanizable dishing and flanging processes for circular-cylindrical floors. Flanging, molding of the brim area and the rim are particularly difficult. On the other hand, the usual base shapes, in which a uniform radius of curvature in the dome area changes into a uniform rim radius, are only suitable to a limited extent for pressing and, in particular, for deep-drawing processes, since there are different and asymmetrical curvature profiles for shapes for non-circular container cross sections, which together with the manufacturing-related strength asymmetries of a usually rolled sheet can lead to deformation anomalies. This can include wrinkles, dents and unwanted thinning or thickening in the starting material that arise during the forming process. Therefore, such floors are manufactured in complex manual molding processes or are assembled from prefabricated sub-elements. An end floor area composed of partial elements for a transport container is, for example, from EP 0 399 099 A known.

For reasons of quality and rationalization, it is therefore desirable to manufacture such floors - for example for elliptical, box-shaped or other asymmetrical cross-sections - with different contour curvatures in a defined tool with reproducible geometry in order to be able to ensure the perfect connection to the same manufactured jacket sections without time-consuming reworking. In particular, there is a need for such, in particular deep-drawn, container bottoms that have a wall thickness of more than 2 mm and are suitable for container cross sections whose diameters are in the order of magnitude of over 500 mm in one axial direction and over 1000 mm in another axial direction and the with a narrow brim radius of about 50 to 75 mm have a curvature depth of more than 250 mm.

Such container bottoms cannot be manufactured with simple deep-drawing processes (one-stage) or only with the above-mentioned quality defects. Multi-stage deep-drawing processes, in which the desired geometry is made in several different tools and several process steps Forming step by step may be suitable, but only economically sensible for large series quantities (several thousand). Thermoforming processes for metallic container components are from the US 2008/0148799 A1 as well as from the EP 0 970 764 A1 known.

It is therefore an object to provide a non-circular container base which can be produced in a single-stage deep-drawing process even with relatively high wall thickness and in comparatively large dimensions and whose end geometry can be produced with repeatable accuracy and with little tolerance in a suitable method and with and with a suitable tool.

SUMMARY OF THE INVENTION

This object is achieved by a container base according to claim 1, or the method according to claim 10. The container base according to the invention has a curved spherical cap region with a radius of curvature R, a connecting contour which has a first radius of curvature in a first contour section and a second radius of curvature in a second contour section , wherein the first radius of curvature is greater than the second radius of curvature and between the circumferential contour and the calotte region a brim region surrounding the dome region and following the connection contour is formed, which has a first brim section with a first brim radius and a second brim section with a second brim radius, the first brim radius is larger than the second brim radius.

The variation of the brim radius in a single contour section with a flatter curvature (larger radius of curvature) optimizes the deformation conditions for a deep-drawing process in this area. The material flow is improved in such a way that a largely wrinkle-free transition of all deformed surfaces into one another can be achieved in a single deep-drawing process, in which a corresponding blank (blank) with the help of a deep-drawing tool, which contains a stamp, a drawing frame and a hold-down device and, if necessary, has a counter shape. The stamp geometry corresponds to the container base geometry.

In this context, the term "deep drawing" denotes both the actual deep drawing, in which the sheet thickness above the drawn part remains approximately constant, that is, the surface of the board is equal to the surface of the drawn part (container bottom), as well as the so-called stretch drawing, in which the The drawn part is shaped by a (partial) surface enlargement at the expense of the sheet thickness.

The shape according to the invention also permits improved pressure resistance (internal overpressure which acts on the concave wall region of the container base), which increases the usability of such a container base for a pressure container. This means that the minimum wall thickness and thus the weight and price (material costs) of the floor can be reduced with the same stability. In addition, the voltage transitions in the flatly curved, cylindrical jacket area must be made smoother.

Further aspects and features of the present invention result from the dependent claims, the attached drawing and the following description of preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWING

Fig. 1

eine perspektivische Ansicht eines ersten Ausführungsbeispiels eines erfindungsgemäßen Behälterbodens,

Fig. 2

eine Schnittdarstellung des Behälterbodens aus Fig. 1,

Fig. 3

eine perspektivische Ansicht eines zweites Ausführungsbeispiels eines erfindungsgemäßen Behälterbodens,

Fig. 4

eine Schnittdarstellung des in Fig. 3 dargestellten Behälterbodens,

Fig. 5

einen stehenden Behälter mit einem erfindungsgemäßen Behälterboden,

Fig. 6

eine Tankcontaineranordnung mit einem liegend angeordneten Behälter mit einem erfindungsgemäßen Behälterboden,

Fig. 7

eine perspektivische Ansicht eines nach dem Tiefziehprozess entstandenen Rohteils für einen Behälterboden entsprechend den Fig. 1-4, und

Fig. 8

einen schematischen Verfahrensablauf eines erfindungsgemäßen Verfahrens zur Herstellung eines erfindungsgemäßen Behälterbodens.

Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings. It shows:

Fig. 1

2 shows a perspective view of a first exemplary embodiment of a container base according to the invention,

Fig. 2

a sectional view of the container bottom Fig. 1 ,

Fig. 3

2 shows a perspective view of a second exemplary embodiment of a container base according to the invention,

Fig. 4

a sectional view of the in Fig. 3 illustrated container bottom,

Fig. 5

a standing container with a container bottom according to the invention,

Fig. 6

a tank container arrangement with a horizontally arranged container with a container bottom according to the invention,

Fig. 7

a perspective view of a blank formed after the deep-drawing process for a container bottom according to the Fig. 1-4 , and

Fig. 8

a schematic process flow of a method according to the invention for producing a container bottom according to the invention.

DESCRIPTION OF EMBODIMENTS

In Fig. 1 One embodiment is illustrated in accordance with the present invention. Before a detailed description follows, general explanations of the embodiments follow.

The term "arched" is used in connection with this application to mean that it is a multiaxially curved surface, like a spherical shape. While the term "curved" denotes a uniaxial surface curvature, like a cylindrical shape.

Furthermore, the following peculiarity applies with regard to the brim area of a floor, which is curved according to the definition given above, but the brim surface has (possibly different) curvatures. Firstly, the curvature, which is indicated by the so-called brim radius or the curvature of the rim. This brim radius lies in a section plane that runs normal to the brim or floor surface and indicates the curvature of the brim area in this plane. In the case of a circular brim area, the brim surface describes a torus or a partial surface of a torus (enveloping surface which forms a circular contour when it is displaced along a ring running through its center). If this curve defining the torus is not circular, but instead has areas with different curvatures - as is the case with non-circular container or floor cross-sections - then the body produced by the brim radius is on the one hand with the one curvature corresponding to the brim radius provided and on the other hand curved according to the curvature of the generatrix.

There are designs in which the first (less curved brim section) is arranged between two more curved brim sections, in such a way that the brim radius does not change abruptly, but rather a transition section is formed between the first brim section and the second brim section, in which the first brim radius merges into the second brim radius. This measure further contributes to the fact that floor structures that are optimized in terms of printing technology and production technology can be formed.

In another embodiment, a third brim section is provided along the second (more curved) contour section, which has a third brim radius. There are versions in which this third brim radius is formed equal to the second brim radius. In other embodiments, the third rim radius can also be made smaller than the second rim radius. There are also further designs in which transition sections are also formed in each case between a third brim section and an adjacent second brim section, so that here also differently curved brim surfaces merge smoothly into one another.

In the case of containers which are used, for example, for the storage and transport of liquids, it is often necessary to provide a connection in the base region of the container, via which a complete emptying of the container is possible. In the case of horizontal containers, a connection suitable for complete emptying must open tangentially into the bottom of the cylindrical jacket. In order to provide a corresponding pipe connection there, namely in the brim area of the tank bottom, a relatively large cutout must be provided there, the contour of which is formed by the intersection line of a pipe tangentially opening into the tank there. This intersection contour is relatively complex and can be problematic in terms of printing and production technology. In addition, a relatively long weld seam is required for the connection, with which a corresponding pipe socket is to be welded into the tank bottom.

There are therefore designs in which, depending on the position of the container, a connection area is formed in the first, second and / or third brim section, which has a connection contour that describes a circular cylinder section, in particular an oblique circular cylinder section. Such a connection area can be formed in the corresponding deep-drawing process by appropriate training on the pressing tool. A connecting pipe to be connected there also only needs to be cut off at an angle, without having to have a complex cutting contour, which would be necessary if it were connected directly to the container brim.

The connection area can be shaped in such a way that it is suitable for both a horizontal (with a horizontal longitudinal axis) and a standing container (with a vertical longitudinal axis). The connection area is then to be shaped such that it starts tangentially from the connection contour - possibly with appropriate fillets - into the collar or rim of the tank bottom (horizontal arrangement of the tank) and / or tangentially into the lowest point of the spherical cap area of the tank bottom ( with the container upright). If a connection is to be provided, the connection area need only be cut out in the area of the connection contour and following it. A corresponding obliquely cut pipe can then be connected there.

There are designs in which the first brim radius is 1.5 to 3 times the second brim radius, in other designs it is 1.8 to 2.5 times, and there are also designs in which it is Is 2 times the second brim radius. These relationships have proven themselves with regard to the manufacture and the printing design of such container bottoms. They allow a design that is favorable in terms of production technology and / or a design that is favorable in terms of printing technology, or else an advantageous configuration with regard to the structural strength of the container in the brim area, which can be connected to support structures there if necessary via intermediate elements.

In other versions, the following relationship exists between the radius of curvature and the first radius of curvature. These are in a ratio of 2.6 to 1 to 1: 1 to each other. In other cases, a range of 1.5: 1 to 1: 1 is provided and there are also versions in which a ratio of 1.2: 1 to 1: 1 is provided. This measure makes it possible to realize containers with different flatness (e.g. oval, double-shelled or box-shaped) and a wide variety of container geometries, which are optimized either in terms of the available space or the pressure resistance.

There are versions in which the first rim radius and the radius of curvature are in a ratio of 1:10 to 1:50, in other versions a range from 1:20 to 1:30 is provided and in other versions there is a ratio of 1 : 25. Here too the relationships between the radius of curvature (the calotte) and the brim radius with regard to different printing requirements or with regard to volume optimization (generally narrower radii of curvature / brim radii) should be formed.

There are versions in which the shape or curvature depth T (corresponds to the "floor height" from the connection contour to the calotte apex) is 3 to 5 times the second rim radius, in particular 3.5 to 4 times and especially 3, 75 times.

There are versions in which a frustoconical and / or cylindrical rim area is formed between the connection contour (to the container jacket) and the brim area. If a truncated cone-shaped area is formed, the connection diameter (or the connection diameter ratios) can be varied by cutting a correspondingly manufactured raw floor at different heights (different height of the board), so that the remaining area of the board is of different lengths / heights. With a short shelf area, the diameter is correspondingly smaller, with a long shelf area, correspondingly larger.

There are also designs in which a cylindrical rim area and a frustoconical rim area are provided in sections in the circumferential direction. Such a design can offer advantages in terms of production technology, since the deformation properties can be improved in this way, particularly in the strongly deformed edge regions.

Container bottoms according to the invention are formed from a ductile, deformable metal material, in particular from a customary stainless steel material (e.g. in the qualities 1.4301, 1.4404; 1.4571).

In the case of box-shaped, oval or approximately elliptical container cross sections, the diameter ratio (large to small diameter; width to height when the container is lying down; width to depth when the container is standing) is 2: 1 to 3.5: 1, in particular 3: 1.

Another aspect of the invention relates to a deep-drawing tool, in particular a stamp, for producing a container base according to the invention.

Another aspect relates to a method for producing a container base according to the invention, which has the following steps: providing a sheet metal blank (plate), deforming the sheet metal blank using a deep-drawing tool to form an intermediate deep-drawing product, and trimming an intermediate deep-drawing product along a peripheral contour, the peripheral contour being formed by a plurality of contour cuts to be carried out in succession becomes. This process helps to carry out the desired connection contour or circumferential contour of the container bottom with repeat accuracy and with little tolerance. Optionally, the method can also include the formation of a connection opening in the deep-drawing intermediate product or in the container bottom.

Coming back to Fig. 1 and 2nd , These show a first exemplary embodiment of a container base 1 according to the invention, which has a curved spherical cap region 2 with a radius of curvature R. The dome area 2 merges via a brim area 3 into an on-board area 4 which ends in a connection contour 5 which corresponds to the cross-section of the container.

The connection contour 5 has a flatly curved first contour section 6 with a first radius of curvature r ₁ in the apex and bottom region. The two first contour sections 6 are connected to one another via second, more curved contour sections 7 in the flank regions, which have a radius of curvature r ₂ , the connecting contour 5 running smoothly over the first and second contour sections 6 and 7.

The brim area 3 surrounding the calotte area 2 adjoins the calotte area 2 with its calotte-side edge 8 and borders with the connection-side edge 9 on the rim area 4, which is optionally formed between the brim area 3 and the connection contour 5. In an embodiment in which no on-board area 4 is provided, the edge 9 on the connection side also forms the connection contour 6.

The brim area 3 has a first brim section 10 with a brim radius r _1k1 in the area of the first contour sections 6. This first brim section 10 merges via an optional transition section 11 into a second brim section 12, which has a second brim radius r _1k2 . The second brim section 12 borders a third brim section 13, which runs in the region of the second contour section 7, and has a third brim radius r _2k3 .

In the exemplary embodiment shown, the optional on-board area 4 running between the brim area 3 and the connecting contour 5 comprises a frustoconical (frustoconical) on-board area 14 and an adjoining cylindrical on-board area 15 which ends in the connecting contour 5.

In other exemplary embodiments, which are not shown, either only a frustoconical rim area 14 is provided or a cylindrical rim area 15 directly adjoins the brim area 3. There are also versions in which, for example, a frustoconical rim area 14 is provided in the area of the first contour section 6, which merges into a cylindrical rim area 15 in the area of the second contour section or vice versa.

In the dome area 2 of the container base 1, depressions 16 are embossed, which are provided for handling the container or the container base 1 during manufacture. There, connecting pieces (for example connecting bolts, threaded bolts etc.) can be provided in a defined position through which the container bottom 1 can be fixed in a defined position in a handling device.

A connection area 17 is formed in the sole area, which has a connection edge 18, the contour of which describes a flat circular cylinder section and is used to connect an obliquely cut-off connection tube 19 (indicated by dashed lines) that can be welded along the connection edge 18. The connection area 17 is designed in such a way that the connection sole 20 is in the same plane with the sole of the cylindrical rim area 15 or the cylindrical container section 31 adjoining the connection contour 5 (see Fig. 5 ) runs. Complete emptying of the entire container 30 can thus be achieved. To connect the connecting pipe 19, the sheet metal disc arranged inside the connecting edge 18 is cut out and the connecting pipe 19 is welded to the connecting edge 18. If no connection pipe 19 is to be provided, the connection area remains closed.

Fig. 3 and 4th show a connection area 17 ', which is both for a standing (see Fig. 6 ) as well as for a lying arrangement (cf. Fig. 7 ) a container or the container bottom 1 is suitable. Here, the connection area 17 ′ is shaped in such a way that it has a connection base 20 that runs in line with the container base, and a connection base 20 ′ that runs tangentially into the low point T of the spherical cap area 2. The connection area 17 ′ also ends here in a connection edge 18, the contour of which corresponds to a straight cylinder section. A removal tube can thus be connected to this connection area 17 ′ along the tube axis 21 (lying container, similar course as in FIG Fig. 2 ) or alternatively along a tube axis 22 (standing container as in Fig. 6 shown, in which the lowest container point is arranged in the low point T of the spherical cap area 2). The connection areas 17, 17 'are each optionally formed in the container bottom 1.

The following table gives typical dimensions for a floor 1 according to the invention with an oval cross section: Radius of curvature R: 4000 mm first radius of curvature r ₁ : 4000 mm second radius of curvature r ₂ : 260 mm first brim radius r _1k1 : 160 mm second rim radius r _1k2 : 80 mm third brim radius r _2k3 : 80 mm Deformation depth T: ∼300 mm long diameter D ₁ : 2100 mm short diameter D ₂ : 700 mm Wall thickness s: ∼2 to 4 mm

Fig. 5 shows a cylindrical container 30 which has a cylindrical jacket section 31 corresponding to the connection contour 5, the upper and lower ends of which are each closed with a container base 1. The two connection contours of the container are each welded to the connection contour 5 of the container bottoms 1 by means of a butt seam. In other embodiments, the container bottom can be pushed into the container section 31 or plugged onto it. The connection is then made via one or two so-called fillet welds. Fig. 5 shows a standing container, the longitudinal axis 32 of which extends vertically. For stabilization, the container has two reinforcement rings 33 which surround the container section 31 and are welded to it. The lower container base 1 is connected to an annular base 34, which serves as a base.

Fig. 6 shows a lying container arrangement, in which a container 30 is also provided, the longitudinal axis 32 of which, however, runs horizontally here. The container is connected at its ends to a frame structure 35 via ring base 34. Frame structure 35 and container 30 form a tank container unit which is suitable for the transport and storage of liquids.

Fig. 7 shows a deep-drawing intermediate product 36 which is produced in the production of a container base 1 according to the invention. Starting from a flat sheet metal blank (round blank), this is deformed by means of a stamp which corresponds to the inner shape of the container base 1. In this case, the edge 37 of the board is fixed on a deep-drawing frame by means of a hold-down device and the shape of the container bottom is formed by pressing the stamp into the board. To produce the final container base 1, the remaining edge 37 on the intermediate deep-drawing product 36 is then removed in one or more cutting processes along the cutting lines 38, so that the connection contour 5 is finally formed on the container base 1. Alternatively to that in connection with the Fig. 2 and 4th described connection areas, which are formed in the container bottom 1, contour cuts 39, 40 can also be provided during production, which are provided for example for connecting a pipe or a fitting.

• Bereitstellen einer Blechplatine,
• Verformen der Blechplatine mittels eines Tiefziehwerkzeugs zu einem Tiefziehzwischenprodukt 36, welches eine Behälterbodengeometrie aufweist,
• Beschneiden des Tiefziehzwischenproduktes entlang einer Umfangskontur 38

This in Fig. 8 The illustrated method for producing a container base 1 according to the invention basically proceeds in the following steps:

• Providing a sheet metal board,
• Deforming the sheet metal plate by means of a deep-drawing tool to form an intermediate deep-drawing product 36 which has a container bottom geometry,
• Trimming the deep-drawing intermediate product along a circumferential contour 38

Optionally, the step can be provided that a connection opening 39, 40 is provided on the deep-drawing intermediate product 36. The depressions 16 or the connection areas 17/17 'can be stamped either in the actual deep-drawing process during the molding of the container base 1 or the deep-drawing intermediate product 36 or in a second step in which the deep-drawing intermediate product 36 is processed accordingly with a further stamping tool.

Claims (11)

1. Vessel head (1) for a vessel (30), manufactured by means of a deep-drawing method, comprising:

   a connecting contour (5) comprising in a first contour section (6) a first radius of curvature (r₁) and in a second contour section (7) a second radius or curvature (r₂),

   wherein the first radius of curvature (r₁) is larger than the second radius or curvature (r₂), characterized in that the vessel head (1) comprises a curved knuckle area (2) with a vault radius (R) and

   a knuckle area (3) surrounding the dish area (2) and tracing the connecting contour (5) is configured between the connecting contour (5) and the dish area (2) comprising, extending along the first contour section (6), a first knuckle section (10) having a first knuckle radius (r_1k1) and a second knuckle section (12) having a second knuckle radius (r_1k2)

   whereby the first knuckle radius and the second knuckle radius each are lying in a sectional plane which is perpendicular to the knuckle surface and/or the floor surface respectively and indicate the curvature of the knuckle section in this plane and whereby the first knuckle radius (r_1k1) is larger than the second knuckle radius (r_1k2).
2. Vessel head (1) according to claim 1, wherein the first knuckle section (10) is disposed between two second knuckle sections (12) and a transition section (11) each is configured between the first and the second knuckle sections (10; 12) in which the first knuckle radius (r_1k1) makes a transition to the second knuckle radius (r_1k2).
3. Vessel head (1) according to claim 2 wherein knuckle surfaces are configured in the first knuckle section (10), in the second knuckle section (12) and in the transition section (11), which make smooth transitions to one another.
4. Vessel head (1) according to claim 1, 2 or 3, wherein a third knuckle section (13) having a third knuckle radius (r_2k3) is configured along the second contour section (7).
5. Vessel head (1) according to any of the preceding claims wherein a connection region (17; 17') is configured in the first, second, and/or third knuckle section (10; 12; 13) comprising a connecting rim (18) which describes a circular cylinder section.
6. Vessel head (1) according to any of the preceding claims wherein the first knuckle radius (r₁) is one and a half to three times, preferably 1.8 to 2.5 times, and in particular two times the second knuckle radius (r₂).
7. Vessel head (1) according to any of the preceding claims where the vault radius (R) and the first radius of curvature (r₁) show a relationship to one another of 2.6:1 to 1:1, preferably 1.5:1 to 1:1, and in particular of 1.2:1 to 1:1.
8. Vessel head (1) according to any of the preceding claims wherein the first knuckle radius (r_1h1) and the vault radius (R) show a relationship to one another of 1:10 to 1:50, preferably of 1:20 to 1:30 and in particular of 1:25.
9. Vessel head (1) according to any of the preceding claims wherein a frusto-conical and/or cylindrical straight flange area (14; 15) is configured between the connecting contour (5) and the knuckle area (3).
10. Method for manufacturing a vessel head (1) according to any of the preceding claims 1-9 comprising:

    - providing a circular metal blank

    - deforming the circular metal blank by means of a deep-drawing tool for manufacturing the vessel head according to any of the preceding claims 1-9 to obtain a deep-drawing intermediate product (36)

    - trimming a deep-drawing intermediate product (36) along a cutting line (38).
11. The method according to claim 10, comprising

    - forming a connection port (39, 40) in the deep-drawing intermediate product (36) and/or

    - forming a connection region (17; 17') comprising a connecting rim (18) that describes a circular cylinder section.

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