EP1037722A1

EP1037722A1 - Device and method for producing shell-shaped metal parts and shell-shaped metal part

Info

Publication number: EP1037722A1
Application number: EP99960800A
Authority: EP
Inventors: Bernd Hachmann
Original assignee: hde Metallwerk GmbH
Current assignee: hde Metallwerk GmbH
Priority date: 1998-10-20
Filing date: 1999-10-20
Publication date: 2000-09-27
Also published as: DE19848290A1; WO2000023211A1; DE19848290C2; AU1768800A

Abstract

The invention relates to a device (10) and a method for producing shell-shaped metal parts, especially for fuel tanks for motorcycles or the like, wherein said parts are produced from flat or preshaped sheet metal elements (40) by means of hydrostatic forming. In order to easily and economically produce particularly complex and generally undercut geometric shapes of parts for outer and/or inner shells of motorcycle tanks without the central welding seams required until now, the device (10) includes a first die part embodied as a core element (11) and a second die part (20). The die parts (11, 20) can be positioned in relation to each other using positioning means in such a way that they limit a forming cavity (30) and wherein at least one metal sheet element (40) is clamped between the die parts (11, 20) by means of sealing surfaces (17, 26, 27) and is formed hydrostatically in the forming cavity (30). The second die part (20) is disposed around the core element (11) in such a way that the positioned core element (11) is surrounded in certain areas by the second die part (20). When the formed sheet metal element (40) has undercuts, the second die part (20) consists of two (21, 22) or more parts for easy removal of the sheet metal element (40).

Description

description

Device and method for producing shell-shaped components made of metal and shell-shaped component made of metal

The present invention relates to a shell-shaped component made of metal and generally to a device and a method for producing shell-shaped components made of metal by means of hydrostatic forming.

Shell-shaped components of the type mentioned are already known in many ways in the prior art and are used, for example, as components for fuel tanks in vehicles or the like.

Fuel tanks can be made of metal or plastic, for example. DE 195 47 148 describes a fuel tank made of plastic material, in which the tank consists of several tank parts which are manufactured in one piece as blow parts. The individual container parts are then connected using a plastic weld seam.

Fuel tanks that are used as motorcycle tanks, for example, are usually made of metal. Such tanks consist of an outer shell and an inner shell which are connected to one another in their edge regions and which delimit a container interior for holding the fuel. Motorcycle tanks of this type have a complex and complex geometry, since they generally have one or more undercuts. In the light of the present description, undercuts are to be understood as secondary shaped elements such as bulges, projections or the like, which are formed perpendicular to the demolding plane. For this reason, previously they had to be produced in individual parts by deep drawing or the like and then using a suitable joining process be connected to each other. This requires the use of complex and costly processes.

If, for example, the outer shell of such an undercut motorcycle tank is to be produced, a left and a right half tank shell have to be produced separately, which can be done, for example, using a deep-drawing process. The two half-shells must then be connected to one another using a joining process, for example a welding process. The arrangement of the joining seam, which is also referred to as the center seam, is in the field of view and must therefore be edited subsequently. Furthermore, the two half-shells can also be distorted during joining. In order to give the outer shell of the motorcycle tank a visually appealing appearance, a series of subsequent operations are required, for example hammers, thimbles, spatulas and loops, which are usually individual for each component. However, this is particularly complex and therefore time and cost intensive. Furthermore, these downstream operations lack the necessary process reliability. In addition, they can only be carried out by hand and by experienced, suitably trained specialist personnel. In addition, there may be inadequate bonds between the individual half-shells in the area of the joint seams, which necessitates a complex inspection of the finished outer shell in order to find defects. If such imperfections appear, it is necessary to add, for example re-weld or the like of the outer shell and a new leak test. However, this is very time and cost intensive.

Because of these problems, there is therefore a need for a bowl-shaped container, in particular a tank, which on the one hand can have a complex geometry, but on the other hand does not have the disadvantages described. This can be achieved, for example, if the container is made of plastic and is manufactured in a blowing process. However, plastic is not always advantageous as a material. A number of types of containers, such as the motorcycle tanks mentioned, are preferably made of metal. Such metal containers with complex, generally undercut geometry of the outer shell and / or inner shell could not previously be produced without the disadvantageous seams in the middle area.

One method with which metal sheets or tubes can be formed into complex geometries in a simple and cost-effective manner is hydrostatic forming. With this forming process, the work of forming water under high pressure is done. If sheet metal is to be formed, the water can be applied alternately to the sheet to be formed either from one side or from both sides, which causes the material to be stretched to the desired shape. The hydrostatic shaping of sheet metal is described, for example, in patent applications DE 44 36 436 and DE 44 36 437, which were also filed by the applicant. The hydrostatic forming of sheet metal enables even complex component geometries to be produced.

Based on the prior art mentioned, the invention has for its object to provide a method and an apparatus for producing shell-shaped components made of metal, with which the disadvantages described above are avoided. In particular, it should be possible to produce shell-shaped components with complex, undercut geometries in a simple and inexpensive manner. Furthermore, an improved bowl-shaped component made of metal, in particular a fuel tank, is to be provided which does not have the disadvantages described in the prior art. According to the first aspect of the present invention, this object is achieved by a shell-shaped component made of metal, in particular a fuel tank, which has an outer shell and an inner shell, the outer shell and the inner shell delimiting an interior of the component. According to the invention, this shell-shaped component is characterized in that the outer shell and / or the inner shell is / are formed in one piece and that the outer shell and / or the inner shell is / are produced by means of hydrostatic shaping.

Such a component is therefore particularly suitable as a motorcycle tank. With regard to the advantages, effects and effects of such a shell-shaped component, reference is also made in full to the following explanations of the device and the method for producing shell-shaped components, and reference is hereby made.

Advantageous configurations of the shell-shaped component result from the subclaims.

In a further embodiment, the outer shell and / or the inner shell can have at least one undercut.

The outer shell and the inner shell can advantageously be connected to one another via a joint connection. Suitable joining connections are, for example, but not exclusively, gluing, riveting, screwing, welding, combinations of these types of joining or the like. A particularly preferred joint is a welded joint.

The joint connection is advantageously provided in the edge area of the shells, which is an uncritical area with respect to the entire component. Since the outer shell and the inner shell are formed in one piece and a previously required central seam is dispensed with, as was described in detail above, it is now also possible to avoid a seam crossing in the region of the joining seam running around the edge region of the shells with a central seam. This seam crossing, which inevitably occurs in the prior art, frequently led to imperfections in the leak test, which made extensive post-processing with a new leak test necessary.

The outer shell and / or the inner shell can advantageously be formed from a cold-formable metal.

According to a second aspect of the invention, a device for producing shell-shaped components made of metal, as described in more detail above, is provided by means of hydrostatic deformation, the shell-shaped components being produced from essentially flat or preformed sheet metal elements. The device has a first die part and a second die part, the die parts being deliverable against one another by means of delivery means in such a way that they delimit a forming cavity in the delivered state and at least one sheet metal element is or is clamped between the die parts and is hydrostatically deformed in the forming cavity. According to the invention, this device is characterized in that the first die part is designed as a core element and that the second die part is arranged around the core element such that the core element is at least partially surrounded by the second die part in the delivered state.

The device according to the invention makes it possible to use flat or preformed sheet metal elements to create shell-shaped components with component geometries which, in terms of shape, surface, complexity and dimensional accuracy, have not hitherto been able to be produced using conventional methods. The invention is not restricted to special types of components. Rather, the device according to the invention can be used to produce any shell-shaped components with a wide variety of geometries and functions.

However, the device can advantageously be used for the production of fuel tanks and here in particular of motorcycle tanks. Particularly in the manufacture of motorcycle tanks, the device and the hydrostatic shaping carried out therein can ensure that the shell-shaped components, for example the outer shell and / or inner shell of the motorcycle tank, no longer have any disadvantageous central seam as described in the prior art.

Due to the fact that the shell-like components can be produced in one piece in the device, the manufacturing time is reduced by saving manufacturing steps, which ultimately also results in a shortening of the entire process chain. Furthermore, the number of parts required is reduced, which also reduces the number of forming tools required.

Thanks to the hydrostatic forming, the shell-like components can be optimally designed depending on the need and application. In particular, complex components with undercuts, such as tank shells or the like, can also be produced in one piece, which was previously not possible with conventional methods and devices.

In the manufacture of tank shells in particular, the previously unavoidable center seams with all of the disadvantages described above can be eliminated. This considerably reduces the need to rework the shell-shaped components after they have been manufactured. Finally, the omission of a central seam also eliminates the risk of imperfections in the joining seam, so that any post-processing that may be necessary for this area Re-welding or the like and a new leak test can be omitted.

The device according to the invention is designed so that the at least one sheet metal element is shaped by means of hydrostatic forming. For this purpose, the sheet metal element to be reshaped is first clamped with its edge region between the two die parts, which can be advanced relative to one another by means of suitable delivery means, for example a number of cylinder-piston units. The sheet is then formed in the forming cavity delimited by the die parts by being exposed to a hydrostatic liquid, for example water. The final shape of the formed sheet corresponds to an engraving which is formed in one or both die parts. Depending on requirements and application, the sheet metal element can first be subjected to a preforming step and then to a final shaping step. The effects and effects as well as the mode of operation of the hydrostatic forming of sheet metal elements are described in detail in the patent applications DE 44 36 436 and DE 44 36 437, which were filed by the applicant and mentioned above and which have already been published, and the disclosure content thereof in the description of the present invention is included.

In the device according to the invention it is provided that the core element is at least partially surrounded by the second die part in the delivered state. In contrast to the devices described in DE 44 36 436 and DE 44 36 437, in the device according to the present invention in the delivered state, not only the surfaces of the two die parts lie against one another in a die division plane. Rather, the core element is also at least partially surrounded by the second die part in its side regions. In this way, curved components such as tank shells or the like can be produced particularly advantageously. Preferred embodiments of the device according to the invention result from the subclaims.

The core element can advantageously have an elongated shape. Such a shape is useful, for example, if an essentially flat sheet metal element is to be formed. This sheet must first be subjected to a bending process, preferably a two-dimensional bending process. This pre-bending is advantageously carried out via the elongated core element.

The core element can preferably have a shape that is as close to the final contour as possible with regard to the sheet metal element to be formed.

In a further embodiment, the core element can have an approximately U-shaped cross section. Of course, the invention is not limited to a specific cross section. Furthermore, it is also possible that the core element can have areas with different cross sections as required. A correspondingly U-shaped cross section allows the sheet metal element to be pre-bent easily and is particularly useful when the sheet metal element is to be shaped as a tank shell for a motorcycle tank.

The core element can advantageously have regions of different heights and / or geometry. The corresponding design of the core element can take place individually, depending on the component to be manufactured.

For example, it is conceivable that the core element in the manufacture of

Tank shells, if it has an essentially U-shaped cross section, has a continuously increasing height over its length. This means that the legs of the "U" become longer and longer. At the same time, however, the width of the rounded base of the "U" can decrease with increasing length of the legs, as a result of which the radius of the base becomes smaller and thus sharper. On such core element would accordingly have a greater width in the region of lower height than in the region of greater height.

In a further embodiment, the shape of the core element can be such that its surface can be developed in one plane. Certain geometric shapes and their surfaces can be developed mathematically in one plane. Such shapes are particularly suitable for the shaping of the sheet metal elements, in particular if the sheet metal elements are present in an essentially flat shape and must first be pre-bent.

The core element and / or the second die part can advantageously have a number of channels which pass through the core element and / or the second die part. A hydrostatic liquid can be directed or can be directed via the channels against the at least one sheet metal element or into the forming cavity. Such channels, which are also described in the referenced DE 44 36 436, are connected via a further line to a corresponding collecting container for the hydrostatic liquid, for example water. The channels point with their openings into the forming cavity.

The second die part can preferably be formed in two parts or in several parts. The second die part can also advantageously be designed in three parts, four parts, five parts or eight parts. Of course, other division options are also conceivable. For example, the second die part can also be formed in one piece.

A multi-part design of the second die part makes sense if the shell-shaped component has one or more undercuts after the hydrostatic shaping has ended. Such undercuts, which are present, for example, in tank shells for motorcycle tanks, would cause the second die part to move apart in a one-piece design second die part and the core element after completion of the forming process impossible.

The parting planes of the individual parts of the second die part can be aligned as desired depending on requirements and needs.

A multi-part design in the manner described above is also conceivable for the core element, for example.

In a further embodiment, the core element and / or the second die part can have an engraving. The engraving determines the shape of the final design of the formed sheet metal element. The engraving is worked into the die part and / or the core element and corresponds to a negative shape of the end contour of the formed sheet metal element.

The second die part and / or the core element can consist, at least in the area of the engraving, of a suitable hard plastic, for example a high-strength polyurethane with a Shore A hardness of 96.

The core element and the second die part can each advantageously have at least one sealing surface, an edge region of the at least one sheet metal element being clamped between the sealing surfaces in the delivered state of the device. The sealing surfaces are preferably closed all round and prevent liquid from escaping from the device in an uncontrolled manner during the shaping process. A suitable sealing element can also be provided in the area of the sealing surfaces.

Preferably, two sheet metal elements can be clamped or clamped between the core element and the second die part. By reshaping a single sheet metal element, it is possible to first produce outer shells and inner shells of the shell-like components, for example motorcycle tanks, in separate work steps, which are then connected to one another using a suitable joining method. By simultaneously forming two sheet metal elements, the two shells of the shell-like components can be formed in a single step. The sheet metal elements can either already be joined or not yet joined before the forming process. In particular, if the two sheet metal elements are joined prematurely, it must be ensured in the subsequent forming process that the hydrostatic liquid can also get between the two sheet metal elements in a sufficient and suitable manner.

According to a third aspect of the present invention, a method for producing shell-shaped components made of metal is provided, as described in more detail above. The method is carried out using a device according to the invention as described above and has the following steps: a) applying at least one essentially flat sheet metal element to the first die part designed as a core element and pre-bending the sheet metal element in such a way that it is adapted to the contour of the core element , or applying at least one preformed sheet metal element to the core element and optionally pre-bending the sheet metal element in the manner mentioned; b) delivering the second die part relative to the core element in such a way that the core element is at least partially surrounded by the second die part, the core element and the second die part delimiting a forming cavity and the at least one sheet metal element being clamped between the die parts; c) hydrostatic forming of the at least one sheet metal element within the forming cavity; d) moving apart the second die part and the core element after completion of the hydrostatic forming process and demolding the at least one formed sheet metal element from the device. The method according to the invention makes it possible to produce shell-shaped components in a simple and inexpensive manner, which can have a complicated contour, in particular with undercuts. In particular, shells for fuel tanks such as motorcycle tanks or the like can be produced by the method, which are formed in one piece and thus no longer have the disadvantageous central seam. Regarding the advantages, effects, effects and the mode of operation of the method according to the invention, reference is made in full to the above explanations regarding the device for producing the components, and reference is hereby made.

It should be mentioned at this point that all forming processes can flow smoothly into one another during the process in order to influence the time-hardening work hardening.

Preferred embodiments of the method result from the subclaims.

Advantageously, two sheet metal elements can be formed simultaneously with the method.

In a further embodiment, after the at least one formed sheet metal element has been removed from the mold, its edge region can be trimmed. By combining the manufacturing process with a flexible process for trimming the formed components, manufacturing costs,

Maintenance, storage of trimming tools or the like for various shell-shaped components are eliminated.

The edge region can preferably be trimmed with a water jet or a laser beam. This type of circumcision will be mechanical Trimming devices are unnecessary, so that a previously required tool change can be omitted at regular intervals. The laser beam as a thermal tool or a corresponding water jet is extremely flexible compared to other mechanical processing processes. Of course, other methods for trimming the edge area are also possible.

The device described above and the method for producing shell-shaped components made of metal can be used particularly advantageously for the production of fuel tanks, in particular motorcycle tanks.

The invention will now be explained in more detail by way of example using exemplary embodiments with reference to the accompanying drawing. 1 to 6 show different perspective views of a device according to the invention for producing shell-shaped components made of metal and such a component, a manufacturing method for such components also being apparent from these figures.

The manufacture of an outer shell for a motorcycle tank is described below with reference to FIGS. 1 to 6.

The outer shell is produced in a device 10 for producing shell-shaped components, as is shown in an overview in FIG. 3. The device has a first die part designed as a core element 11 and a second die part 20. The second die part 20 consists of two die part halves 21 and 22.

The core element 11 has an elongated shape and an approximately U-shaped cross section 12. The die part halves 21 and 22 can be adjusted relative to the core element 11 in such a way that they have a forming cavity in the delivered state Limit 30. In addition, the core element 11 is completely surrounded by the die part halves 21, 22 except for its end faces 13.

The positioning of the die part halves 21, 22 and the core element 11 is supported by corresponding fixing areas 14, 15, 23, 24.

For clamping a sheet metal element 40 during the later hydrostatic shaping, the core element 11 has a sealing surface 17 which corresponds to corresponding sealing surfaces 26, 27 of the die part halves 21 and 22. The sheet metal element 40 is clamped between the sealing surfaces 17, 26, 27. The sealing surfaces also have the task of preventing the hydrostatic liquid entering the forming cavity 30 during the forming process from uncontrolled escape from the device 10. A suitable sealing element can be provided in the area of the sealing surfaces 17, 26, 27 communicating with one another.

A number of channels, not shown, are provided within the core element 11 and are connected to a collecting container for the hydrostatic liquid, also not shown. The hydrostatic liquid is pressed against the sheet metal element 40 during the forming process via the channels which pass through the core element 11 and, depending on requirements, also the second die part 20, so that it deforms plastically. The shape of the formed sheet metal element 40 is determined by the shape-determining engraving 25 in the second die part 20. Depending on requirements, such an engraving can also be formed in the core element 11.

The shape of the core element 11 is shown in Fig.2. The core element 11 has the approximately U-shaped cross section 12. The core element 11 has a height h1 on its end face 13, the height continuously increasing to a height h2 up to the opposite end face. Simultaneously g decreases with increasing Height of the radius from the base of the "U" in cross-section 12. The legs of the "U" in cross-section 12 stand closer together at height h2 and are therefore steeper than is the case at height h1. The core element thus has an uneven shape. However, the surface 16 of the core element 11 (see FIG. 1) can be developed mathematically in one plane. Due to its design, the core element 11 has a contour that is suitable for the outer shell of the motorcycle tank that is to be produced and is as close as possible to the end.

If the outer shell of the motorcycle tank is now to be produced from an essentially flat sheet metal element 40, the sheet metal element 40 must first be pre-bent in a two-dimensional manner, as shown in FIG. For this purpose, the sheet metal element 40 is bent over the apex of the core element 11. The sheet metal element 40 bent over the core element 11 can be seen from FIG.

Subsequently, as shown in FIG. 3, the two die part halves 21, 22 of the second die part 20 are relatively advanced against the core element 11 in such a way that they limit the forming cavity 30 in the delivered state. At the same time, the sheet metal element 40 is clamped and fixed between the sealing surfaces 17, 26, 27.

A relative feed movement of the core element against the second die part 20 can mean that, as shown in the exemplary embodiment, the core element 11 is immovably fixed, while the second die part 20 is arranged movably in the device 10. Of course, the reverse case is also conceivable that the second die part 20 is immovable and the core element 11 is arranged to be movable. Finally, both the core element 11 and the second can

Die part 20 can be arranged to be movable relative to one another.

The delivered state of the device 10 shortly before the actual forming process is shown in FIGS. 4a and 4b. With the start of the hydrostatic forming, the hydrostatic liquid is passed through the corresponding channels in the Core element 11 pressed against the sheet metal element 40. As a result, the core element 40 is subjected to a plastic deformation in the region of the forming cavity 30, to the extent that the deformed region 42 of the sheet metal element 40 bears against the engraving 25 located in the second die part 20. This state is shown in Fig.5a.

As can be seen particularly clearly from FIG. 5 a, the sheet metal element 40 has an edge region 41 which is clamped between the sealing surfaces 17, 26, 27 and is therefore practically excluded from deformation. The sheet metal element 40 is usually only deformed in the forming area 42. If necessary, sheet metal can flow from the edge area into the forming zone.

After the hydrostatic shaping has ended, the two die part halves 21 and 22 are moved apart, so that the deformed sheet metal element 40, which now has the shape of an outer shell of a motorcycle tank, can be demolded without problems. The division of the second die part 20 into several parts is particularly advantageous in the production of outer shells for motorcycle tanks if they have one or more undercuts, which would make it impossible for the formed sheet metal element 40 to be removed from the device 10 if the second die part 20 were only in one piece .

After removal from the device 10, the formed sheet metal element has the contour shown in FIG. 5b. Now the edge region 41 of the sheet metal element has to be cut away, which can be done using a suitable cutting method, for example using a laser beam or a water jet.

The finished outer shell 40 for the motorcycle tank is shown in Fig.6. As can be clearly seen from this figure, the outer shell is made in one piece, so that the previously inevitable central seam, which arose in the known production of the outer shell from a left and a right half-shell, is omitted.

The production of an outer shell for a motorcycle tank has been described in the figures. Inner shells for such a tank can also be produced in the same way. With a corresponding modification of the device 10, it is also possible to reshape two sheet metal elements at the same time, so that both the outer shell and the inner shell can be produced in a single operation.

Claims

claims

1) Shell-shaped component made of metal, in particular fuel tank, which has an outer shell (40) and an inner shell, the outer shell (40) and the inner shell delimiting an interior of the component, characterized in that the outer shell (40) and / or the inner shell are formed in one piece is / are and that the outer shell (40) and / or the inner shell is / are manufactured by means of hydrostatic forming.

2) Shell-shaped component according to claim 1, characterized in that the outer shell (40) and / or the inner shell has / have at least one undercut.

3) Shell-shaped component according to claim 1 or 2, characterized in that the outer shell (40) and the inner shell are connected to one another via a joint connection.

4) Shell-shaped component according to one of claims 1 to 3, characterized in that the outer shell (40) and / or the inner shell is formed from a cold-formable metal.

5) Device for producing shell-shaped components made of metal according to one of the

Claims 1 to 4 by means of hydrostatic forming, the shell-shaped components being produced from essentially flat or preformed sheet metal elements, with a first die part (11) and with a second die part (20), the die parts (11, 20) being relatively relative via feed means are mutually deliverable, that they are in the delivered state delimit a forming cavity (30) and wherein at least one sheet metal element (40) is or is clamped between the die parts and is hydrostatically formed in the forming cavity (30), characterized in that the first die part is designed as a core element (11) and that the second die part (20) is arranged around the core element (11) such that the core element (11) is at least partially surrounded by the second die part (20) in the delivered state.

6) Device according to claim 5, characterized in that the core element (11) has an elongated shape.

7) Device according to claim 5 or 6, characterized in that the core element (11) has an approximately U-shaped cross section (12).

8) Device according to one of claims 5 to 7, characterized in that the core element (11) has areas of different heights (h1, h2) and / or geometry.

9) Device according to one of claims 5 to 8, characterized in that the core element (11) is designed in its shape such that its surface (16) can be developed in one plane.

10) Device according to one of claims 5 to 9, characterized in that the core element (11) and / or the second die part (20) a number of

Has channels which penetrate the core element (11) and / or the second die part (20) and that a hydrostatic liquid is directed or can be directed via the channels against the at least one sheet metal element (40) or into the forming cavity (30). 11) Device according to one of claims 5 to 10, characterized in that the second die part (20) is formed in two parts (21, 22) or in several parts.

12) Device according to one of claims 5 to 11, characterized in that the core element (11) and / or the second die part (20) has an engraving (25).

13) Device according to one of claims 5 to 12, characterized in that the core element (11) has at least one sealing surface (17), that the second die part (20) has at least one sealing surface (26, 27) and that in the delivered state Edge area (41) of the at least one

Sheet metal element (40) is clamped between the sealing surfaces (17, 26, 27).

14) Device according to one of claims 5 to 13, characterized in that two sheet metal elements between the core element (11) and the second die part (20) are clamped or clamped.

15) Method for producing shell-shaped components made of metal according to one of claims 1 to 4, using a device according to one of the

Claims 5 to 14, with the following steps: a) applying at least one substantially flat sheet metal element to the first die part designed as a core element and pre-bending the sheet metal element in such a way that it

Contour of the core element is adapted, or applying at least one preformed sheet metal element to the core element and optionally pre-bending the sheet metal element in the manner mentioned; b) delivery of the second

Die part relatively against the core element in such a way that the

Core element is at least partially surrounded by the second die part, the core element and the second die part delimiting a forming cavity and the at least one sheet metal element between the die parts is pinched; c) hydrostatic forming of the at least one sheet metal element within the forming cavity; d) moving apart the second die part and the core element after completion of the hydrostatic forming process and demolding the at least one formed sheet metal element from the device.

16) Method according to claim 15, characterized in that two sheet metal elements are formed.

17) Method according to claim 15 or 16, characterized in that after the removal of the at least one formed sheet metal element, the edge region is trimmed.

18) Method according to claim 17, characterized in that the edge region is trimmed with a water jet or laser beam.

19) Use of a device according to one of claims 5 to 14 and / or a method according to one of claims 15 to 18 for the production of fuel tanks, in particular motorcycle tanks.