DEVICE AND METHOD FOR PRODUCING A HOLLOW BODY FROM A WORKPIECE IN THE FORM OF A ROUND BLANK

Abstract

The invention relates to a device for producing a hollow body from a workpiece in the shape of a circular blank, comprising a forming mandrel supported in a rotationally driven manner, a pressing element which is also supported on the machine bed in a rotating manner and in an axially displaceable manner relative to the forming mandrel for clamping the workpiece, and at least one forming roller which can be fed axially and/or radially to the forming mandrel. The provision is made that on the pressing element at least one forming die is arranged, into which the forming mandrel can be entered axially for forming the workpiece and that the forming die can be displaced axially with respect to the pressing element. The invention further relates to a method for producing a hollow body from a workpiece in the shape of a circular blank.

Description

The invention relates to a device for producing a hollow body from a workpiece in the shape of a circular blank, in particular a spinning/flow-forming machine, comprising a forming mandrel which is supported in a rotationally driven manner about an axis of rotation, a pressing element which is supported about the axis of rotation in a rotatable manner and in an axially displaceable manner relative to the forming mandrel for clamping the workpiece, and at least one forming roller which can be fed axially and/or radially to the forming mandrel.

The invention further relates to a method for producing a hollow body from a workpiece in the shape of a circular blank.

Hollow bodies of such type can be employed for example as pressure containers. Pressure containers that have to withstand a filling pressure of up to several hundred bars are used for compressible or liquid gases, such as CNG (compressed natural gas), LNG (liquefied natural gas) or high-pressure hydrogen gas. The pressure containers are used for instance in motor vehicles as pressurized gas bottles for natural gas tanks and for the hydrogen supply of fuel cells.

From the prior art a variety of methods and devices for producing pressure containers are known.

For example DE 25 17 971 teaches the production of gas bottles from a block. This block is punched on a press in such a manner that a base part remains and in this way it is formed into a hollow cylinder with a base located on one side. Said hollow cylinder is then formed into a gas bottle blank and is subsequently cold stretched into the final shape on a flow-forming machine.

DE 39 10 192 A1 proposes that tube sections, obtained by cutting to length of hotproduced tubes, are formed through hot forming into a closed container. When forming the base an upset nose develops on the inside at the base centre, which is removed mechanically by an additional method step. Furthermore, provision is made for the wall thickness of the central cylindrical part to be reduced through cold forming. However, since the various method steps as a rule need to be carried out in different processing stations, the previously known method can also be comparatively laborious.

DE 197 11 844 B4 teaches a further method for producing a pressure container. According to this method a respective pot-like part is produced from two circular blanks in the flow-forming method, the pot-like parts being thereafter welded together to the container. The welding may have a negative effect on the stability and corrosion characteristics of the material.

From DE 16 52 630 C a method for producing cooking pots with a cylindrical wall is known. In accordance with this method provision is made for the edge of a circular blank to be initially folded over in a cylindrical manner through flow-forming and to be stretch-formed afterwards.

The object of the invention is to provide a device and a method for producing a hollow body, in particular a pressure container, from a workpiece in the shape of a circular blank, by means of which especially stable and tight hollow bodies can be produced in a simple and economical way.

In accordance with the invention the object is solved by a device having the features of claim 1 as well as by a method having the features of claim 5. Preferred embodiments are stated in the respective dependent claims.

The device according to the invention is characterized in that on the pressing element at least one forming die is arranged, which can be moved axially relative to the forming mandrel for forming the workpiece and in that the forming die can be displaced axially relative to the pressing element.

A first fundamental idea of the invention resides in the fact that an additional forming die is arranged on a spinning and/or flow-forming machine such that through axial movement of the die and/or the forming mandrel the workpiece can be drawn into the die and thereby be formed. This renders it possible for the workpiece clamped in the machine to be formed in one and the same setting in a deep-drawing or pressing operation and in a spinning and/or flow forming operation. For example through deep drawing or pressing a base portion of the hollow body can be formed in the forming die and through subsequent flow-forming a cylindrical wall portion and/or a neck portion of the hollow body can be formed to completion.

Another fundamental idea of the invention can be seen in the fact that the forming die is provided in an axially displaceable manner on the pressing element. In this way it is possible to retract the forming die from the front face of the pressing element and the workpiece after deep drawing or pressing so that the said forming die does not obstruct the feeding of the at least one forming roller. As a result, especially workpiece portions that have been formed beforehand through deep drawing or pressing can then be processed further by spinning or flow-forming without the necessity to reclamp the workpiece in a laborious way.

Consequently, the device according to the invention allows for an especially easy, quick and therefore economical production of the hollow body. Compared to other forming methods it is possible to cut down on method steps such as intermediate annealing and etching as well as bonderizing required for descaling.

Compared to the production from tubes the method according to the invention is considerably cheaper. In addition, the flat sheet metal required as starting material can not only be procured at a lower price but is also freely available in a great variety of sheet thicknesses. A limitation of the container diameter to the tube diameters offered does not exist. Besides to the method according to the invention any chosen diameter/wall thickness ratio can therefore be adjusted. Consequently, a high degree of flexibility is provided. It is also possible for individual portions of the container to be freely adjusted in their wall thickness. In comparison with hot forming by way of forging substantially lower investment costs are incurred for the method according to the invention. In contrast to the required forging molds the device according to the invention can be employed with a high degree of flexibility for a great variety of workpieces.

For best suitability the forming die surrounds the pressing element in a ring-like manner. Advantageously, the forming die has an inner contour that tapers with respect to an increasing axial distance from the extended forming mandrel. The pressing element is preferably arranged in the crown of the inner contour of the forming die. Depending on the desired base shape of the hollow body the pressing element can have e.g. a convex, a concave or a plane front surface.

By preference, the forming die can be displaced in such a manner that, when located in a working position, it protrudes axially from the front face of the pressing element directed towards the forming mandrel and, in a retracted position, it is set backwards axially with respect to this front face. For best suitability, in the forming position of the forming die the contour of the front face of the pressing element is adjacent flush to the inner contour of the forming die.

The versatility and working speed of the device according to the invention can be increased in that in the forming mandrel and/or in the pressing element a stamp is arranged, which can be moved frontally out of the forming mandrel or the pressing element, respectively, for carrying out a forming operation. Such a stamp can be used for example for forming a container neck. By preference, the stamp can be displaced axially, i.e. in the direction of the axis of rotation, in which case it is suitable for the axis of rotation to extend centrally through the stamp.

The versatility of the device according to the invention can be increased further in that the forming die has several die elements that can be moved axially relative to one another. As a result, it is possible to successively carry out several different forming operations in the same setting. For best suitability, the die elements are arranged coaxially and/or surround one another in a ring-like manner.

In the method according to the invention for producing a hollow body from a workpiece in the shape of a circular blank provision is made for a base portion of the hollow body to be formed through deep drawing or pressing in a central portion of the workpiece and for an external portion of the workpiece, which has been set into rotation, to be folded over, in particular flow-formed into a cylindrical shape by feeding at least one forming roller. Here, it is also possible to initially produce a conical or funnel-shaped preform for example through projected forming. This preform is then formed into the cylindrical shape in one or several working steps.

The method can be carried out in particular by means of a device in accordance with the invention, in which case the advantages set out in this connection can be achieved.

Another fundamental idea of the invention can be regarded in the fact that for the production of the hollow body the workpiece in the shape of a circular blank is first of all processed in its centre by being moved into a forming die. The external portion of the workpiece can remain unformed or it can also be folded over e.g. into a preform preferably truncated cone-like. In a subsequent spinning or flow-forming method the external portion is then folded over into a cylindrical shape.

By way of the method according to the invention it is possible to produce a hollow body, more particularly a pressure container, in an especially energy-saving and economical way whilst ensuring an especially low weight, high stability and a minimum of contamination in the inside of the container.

The economical aspect of the method according to the invention can be ascribed inter alia to the use of circular blanks that are available at low cost in finely graded thicknesses with a good surface quality and with minimum tolerance.

The deep drawing or pressing according to the invention can include one or several forming operations. According to the invention this can take place while the workpiece is at standstill, by preference, also when the workpiece is rotated.

The processing speed can be increased further in that the deep drawing or pressing of the central portion and the folding-over of the external portion are carried out in the same setting. For this purpose use is advantageously made of a spinning/flow-forming machine, in which a forming die is arranged on the front ahead of the forming mandrel. By preference, a device according to the invention is employed.

The economical aspect of the method can be enhanced further by the fact that during deep drawing or pressing the external portion is formed in particular in a funnel-like manner. According to this embodiment the external portion is made into a preform during deep drawing or pressing and is thereafter folded over into the cylindrical shape by means of a forming roller. As a rule, the workpiece is heated before the deep drawing or pressing. In such case the external portion can be formed particularly well. A funnel-like shape can be understood in particular as a rotationally symmetrical shape having a tapering cross-section, in which case the wall can extend in the longitudinal section in a convex, concave or straight manner so that in particular a conical shape is present.

Alternatively, provision can also be made for the external portion to be left unformed during the deep drawing or pressing. This may be particularly of advantage in the case of workpiece materials that are difficult to process or in the case of large circular blank overlaps for pressure containers having large diameters and a great length.

An especially high quality of the hollow body can be achieved in that the external portion is supported during the deep drawing or pressing. To this end e.g. a preferably ring-shaped hold-down fixture can be provided that is applied to the workpiece on the side facing away from the forming die. Additionally or alternatively, at least one supporting roller can be provided. For example at least a pair of supporting rollers can be provided, in which case then it is suitable for the workpiece to be guided through in the external portion between two adjacent supporting rollers of the supporting roller pair. It is also possible for at least one forming roller to be fed that supports the workpiece. If rollers are provided for the support, the workpiece is suitably rotated at low speed during the deep drawing or pressing.

In accordance with the invention especially well-defined wall thicknesses result from the fact that, during folding-over or at least in a further roller pass, the workpiece is stretch-formed in the portion of the cylindrical shape. It is possible to adjust a defined wall thickness or a defined cold work-hardening.

Moreover, it can be of advantage that during stretch-forming a change of the wall thickness is produced in an end portion of the cylindrical shape, in particular through split adjustment. A small reduction of the wall thickness can be employed for the production of a container neck and/or a connecting piece for filling. The thickness of the edge is preferably designed in a multi-stage manner. Advantageously, this is then provided if the wall thickness of the cylindrical shape is small and/or is thinned substantially in relation to the starting thickness of the workpiece.

An especially versatile method is provided in that during the deep drawing or pressing the wall thickness is changed in the central portion. This can be achieved by an appropriate design of the pressing element and/or the forming die, the forming mandrel as well as the forming speeds and/or the forming force. It is also possible for the wall thickness to be increased.

Especially then if a container connection is to be provided in the base portion of the hollow body it is of advantage that a preform designed as a punched circular blank with a nose formed thereon is used for the deep drawing or pressing. Basically, use can be made for example of preforms consisting of punched circular blanks with or without central bore, with or without nose, with or without container base formed thereon and/or conical or cup-like preforms.

By preference, through a reduction of the wall thickness material can be obtained which is formed to a thickened nose.

For instance for the production of a container connection located on the side of the base alternative or additional provision can be made that, in particular after the deep drawing or pressing, material is removed in the base portion and formed to a flange by means of at least one roller. This method step, which is suitably carried out in the same setting as the deep drawing or pressing and/or the folding-over, can also be provided before the deep drawing or pressing. By preference, material is removed by means of at least one splitting roller, which can then be formed, in particular by at least one chambered forming roller, for example to a container connection, a connecting piece or the neck of a bottle.

Furthermore, it is especially advantageous that before the deep drawing or pressing the workpiece is heated in particular to a forming temperature above the recrystallization temperature. Additionally or alternatively, provision can be made for heating before or after the folding-over, stretch-forming and/or a reduction of the cylindrical shape. This can take place with known heating devices, such as gas burners or an inductive heating device. Preferably, the forming mandrel and/or the die can also be heated by an internal heating device.

Furthermore, provision is made according to the invention that after folding-over and especially after the stretch-forming of the cylindrical shape the end portion of the cylindrical shape is drawn-in by feeding at least one draw-in roller and is closed, in particular by forming a container neck. As a result, the hollow body can be designed as a gas container in an economical and rapid way.

In the following the invention will be described in greater detail by way of preferred embodiments which are shown schematically in the drawings, wherein:

FIGS. 1 to 5 show method steps during the implementation of the method according to the invention with a device according to the invention;

FIG. 6 shows the method step of FIG. 3 in a differently designed device according to the invention;

FIGS. 7 to 10 show method steps of the method according to the invention in accordance with a first variant with a device according to the invention;

FIG. 11 shows the method step of FIG. 7 in a differently designed device according to the invention;

FIGS. 12 to 17 show method steps of the method according to the invention in accordance with a second variant with a device according to the invention;

FIGS. 18 and 19 show method steps of the method according to the invention in accordance with a third variant with a device according to the invention;

FIGS. 20 and 21 show method steps of a fourth variant of the method according to the invention with a device according to the invention;

FIGS. 22 to 26 show method steps of a fifth variant of the method according to the invention with a device according to the invention;

FIGS. 27 to 29 show a further method variant in accordance with the invention;

FIGS. 30 to 32 show another method variant in accordance with the invention;

FIGS. 33 to 35 show a further embodiment according to the invention for forming a material accumulation on a container;

FIGS. 36 to 38 show method steps of a further variant of the method according to the invention with a device according to the invention;

FIGS. 39 to 42 show method steps of a different variant of the method according to the invention;

FIG. 43 shows method steps of the method according to the invention in accordance with a further variant;

FIGS. 44 and 45 show method steps during the implementation of the method according to the invention with a device according to the invention in accordance with a further variant;

FIG. 46 shows finishing method steps in the production of a gas container.

Elements having the same or a similar effect are designated in all embodiments with the same reference signs. Basically, the different method variants can be combined freely.

In FIGS. 1 to 5 method steps of a method according to the invention with a device according to the invention in accordance with a first embodiment are shown. In accordance with the illustrated method a workpiece 1 in the shape of a circular blank is initially heated to forming temperature in a supply device 51 with a holder (FIG. 1). To this end the supply device 51 can have e.g. a furnace, a flame generating device and/or an induction device.

Afterwards, the workpiece 1 is clamped into a device according to the invention designed as a spinning/flow-forming machine (FIG. 2). The spinning/flow-forming machine has a forming mandrel 11 as well as a pressing element 18 that lies frontally opposite the forming mandrel 11. The forming mandrel 11 and the pressing element 18 are arranged on a machine bed, not illustrated here, such that they can be driven in a rotating manner about an axis of rotation 10 and can be displaced axially relative to one another.

The pressing element 18 is surrounded by a ring-like forming die 40 that can be displaced relative to the pressing element 18 between a forming position shown in FIGS. 2 and 3 and a retracted position shown in FIGS. 4 and 5. In the forming position the forming die 40 protrudes axially from the pressing element 18 in the direction of the forming mandrel 11. The pressing element 18 and the forming die 40 can be designed in particular as a hydraulically actuated pressing unit.

As depicted in FIG. 2, the workpiece 1 is clamped between the forming mandrel 11, which contains the inner shape of the finished hollow body, at least of its base, and the forming die 40, which contains together with the pressing element 18 the outer shape of the finished hollow body, at least in the portion of the container base. Depending on the desired base shape of the hollow body the pressing element 18 can be designed at its front face in a concave (FIG. 3), convex (FIG. 6) or plane manner (not illustrated). More particularly, an arched or circular contour can be provided.

As shown in FIG. 3, the forming mandrel 11 is then moved axially into the forming die 40, with this relative movement being preferably carried out through a simultaneous movement of the pressing element 18 and the forming die 40 on the machine bed while the forming mandrel 11 is stationary.

During inward movement of the forming mandrel 11 the base portion of the hollow body is formed in one forming operation in a central portion 4 of the workpiece 1. At the same time an external portion 5 located further outwards in the radial direction is formed into a cone-shaped shell (FIG. 3).

Afterwards (FIG. 4) the forming die 40 on the pressing element 18 is retracted axially from the forming mandrel 11 and is thereby taken out of the working area. The pressing element 18, which is arranged in the centre of the forming die 40 and has at its front face a pressing disk with a smaller diameter as compared to the forming die 40, continues to press the workpiece 1 in the base portion against the forming mandrel 11.

The forming mandrel 11, the pressing element 18 and the workpiece 1 clamped inbetween are then set into rotation about the axis of rotation 10 and at least one forming roller 31 designed as a flow-forming roller is fed to the workpiece 1. In at least one pass of the flow-forming roller the external portion 5 is bent into a cylindrical shape 8 towards the forming mandrel 11, is stretch-formed (FIG. 5) and stripped off the forming mandrel 11 by means of a stripping device not shown here. This method can be employed in particular in the case of a medium thickness of the circular blank, a material that is easy to form and in the case of circular blanks having a medium overlap.

To achieve an improved forming a supplementary heating can be provided during the processing with the at least one forming roller 31.

In FIGS. 7 to 10 a variant of the method according to the invention is explained. In contrast to the previously described embodiment, in which the entire workpiece 1 is formed during the pressing and/or deep drawing, in the forming operation depicted in FIG. 7 of the embodiment of FIGS. 7 to 10 the external portion 5 of the workpiece 1 remains unformed, i.e. only a part of the workpiece undergoes forming.

Only in a further step (FIGS. 8 and 9) the external portion 5 is first of all folded over cylindrically by at least one forming roller 31 designed as a flow-forming roller and is subsequently stretch-formed to the final dimensions in at least one roller over-run (FIG. 10) by means of flow-forming.

This method variant is especially suitable for circular blanks having a smaller overlap and therefore for smaller containers.

In this case, too, the pressing element 18 can have a convex (FIG. 11) or concave (FIG. 7) design depending on the desired base shape.

A further method variant which is particularly suitable for large workpiece thicknesses and/or for materials that are difficult to process is illustrated in FIGS. 12 to 17.

In this method variant, too, the workpiece is only formed in the central portion 4 in the initial forming operation, while the external portion 5 lying further outwards in the radial direction remains unformed (FIGS. 12 and 13).

Through spinning or projected forming a funnel-shaped preform is then produced (FIGS. 14 and 15), the shell of which widens towards the area of the opening. The funnel-shaped preform can have a constant or a varying wall thickness.

Through continued spinning (FIG. 16) the external portion 5 of the workpiece 1 is foldedover adjacent to the forming mandrel 1 and is formed into a cylindrical shape 8. In doing so, it can be ensured that a sufficient amount of material is available for the subsequent forming of a second container base as well as for a connecting piece arranged thereon.

Afterwards (FIG. 17) the cylindrical shape 8 is stretch-formed to the final dimensions through flow-forming in at least one roller over-run.

Another method variant is shown in FIGS. 18 and 19. Likewise, in this method variant only the central portion 4 of the workpiece 1 is initially formed during the pressing or deep drawing. To prevent crease formation in the external portion 5 of the workpiece 1 during the forming, provision is made according to this method variant for the workpiece 1 to be rotated at low speed during the forming operation and for the external portion 5 to be supported by means of supporting rollers 61, 62. The supporting rollers 61, 62 constitute a supporting roller pair, in which case one supporting roller 61 supports the workpiece 1 on the side of the pressing element 18 and an adjacent supporting roller 62 supports it on the side of the forming mandrel 11. The axes of rotation of the supporting rollers 61, 62 extend perpendicularly to the axis of rotation 10 of the workpiece 1.

A further method variant, in which the workpiece 1 is supported during the forming operation, becomes apparent from FIGS. 20 and 21. To support the external portion 5 of the workpiece 1 in this method variant a forming roller 31 is fed during the first forming operation to the external portion 5 of the workpiece 1 on the side of the pressing element 18 and the workpiece 1 is rotated at low speed.

For the method variant depicted in FIGS. 22 to 24 a device is employed, in which a stamp 13 is provided, which is located centrally in the forming mandrel 11 and can be moved axially relative to the said forming mandrel 11. In the pressing element 18 a recess 14 corresponding to the stamp 13 is provided.

In the method variant shown in FIGS. 22 to 26 two forming operations are carried out prior to the flow-forming. Just as in the previously described embodiments, in the first forming operation (FIG. 23) the pressing element 18 is moved forwards axially on the machine bed together with the surrounding forming die 40 and, in doing so, the opposite lying forming mandrel 11 is moved into the forming die 40, whereby the workpiece 1 undergoes forming.

In the ensuing second forming operation (FIG. 24) the stamp 13 is moved frontally out of the forming mandrel 11 into the recess 14. In this forming operation effected out of the forming mandrel 11 towards the pressing element 18 a container nose can be formed. If required, said container nose can then be formed to size by a forming roller.

According to FIG. 25 the forming die is retracted so as to provide a free space for a subsequent forming roller 31. According to FIG. 26 a selected wall thickness distribution 28 is produced through split adjustment of the forming roller 31 during the stretch-forming.

For the method explained in FIGS. 22 to 26 use is suitably made of a centrally punched circular blank.

As an alternative to the previous method step according to FIG. 26, according to FIGS. 27 to 29 the outer edge of the workpiece 1 can be formed into a conical shape by means of a forming roller 31 through projected forming in the axial direction, as illustrated in FIG. 28. According to FIG. 29 the workpiece preformed in this way can then be folded over onto the forming mandrel 11 and stretch-formed in its wall thickness and finish-formed to the cylindrical shape 8 by means of the forming roller 31.

Another alternative is shown in FIGS. 30 to 32. Unlike the method variants described before, the workpiece 1 is formed by means of the forming roller 31 into a bell-shaped or funnel-shaped preform in one or several roller passes, as can be clearly taken from FIG. 31. Afterwards, just as in the previous method, the folding-over and final forming of the cylindrical shape 8 takes place by means of the forming roller 31.

In accordance with FIGS. 33 to 35 a method variant is shown, in which an accumulation of material 3 can be formed out centrally on the workpiece 1 by means of a forming roller 31, which can be used for example for a container connection. In an external portion of the workpiece the forming roller 31 is pressed into the wall of the workpiece and moved towards the pressing element 18. As a result, the displaced or partially separated material is shifted by the pressing element 18, which can move aside according to the invention in the axial direction and thereby provide a free space for the material accumulation 3. For example a threaded bore for a valve element can be applied to the material accumulation 3.

According to the method variant of FIGS. 36 to 38 a preform designed as a punched circular blank with a nose 2 formed thereon is used as a workpiece for the deep drawing or pressing. This preform is heated in the supply device 51 (FIG. 36). Afterwards, the container base is designed by a forming operation (FIGS. 37 and 38).

In this embodiment, too, the pressing element 18 has a recess 14 at the front face, which receives the nose 2 during the forming operation. In the finished hollow body the nose 2 can serve as a container connection.

In the method variant of FIGS. 39 to 42 the deep drawing or pressing for the forming the base portion of the hollow body (FIG. 40) and the ensuing folding-over of the external portion 5 (FIG. 42) are carried out in different settings. To this end a respective heating step can be provided both before the deep drawing or pressing as well as before the flow-forming (FIG. 39 and respectively FIG. 41).

In accordance with the embodiment of FIG. 43 a heating device with a holder as well as a forming tool are provided in the supply device 51.

In the embodiment of FIGS. 44 and 45 a device according to the invention is employed, in which the forming die 40 has two coaxially arranged die elements 41, 42 that can be displaced axially relative to each other.

During the first forming operation depicted in FIG. 44 the outer die element 42 is arranged such that it is aligned at the front face with the inner die element 41. In this way the workpiece 1 is supported in its external portion 5 by the die element 42. To form the central portion 4, here the forming mandrel 11 is entered into the first die element 41.

In a further forming operation depicted in FIG. 45 the inner, first die element 41 is retracted from the forming mandrel 11 and the second, outer die element 42 is advanced. As a result, the forming mandrel 11 also enters into the conical opening of the second die element 42, whereby the external portion 5 of the workpiece 1 is folded over in a funnel-shaped manner.

The outer die element 42 can then also be retracted from the forming mandrel 11 and the external portion 5 can be folded over cylindrically through flow-forming.

FIG. 46 shows a further method step that can be provided for closing the hollow body after the forming of the cylindrical shape 8. In this method step the workpiece 1 is heated to forming temperature, clamped at its base portion by a chuck into a spin-draw-in machine and is set into rotation. The end portion 7 of the workpiece 1 is then closed, if required upon an additional supply of heat, by a pivotable draw-in roller 38 in at least one pass to a container neck with nose (FIG. 46 on the right side) or without nose (FIG. 46 at the centre). The wall thickness of the container neck can be chosen thinner, equally thick or thicker than the starting thickness of the workpiece.

Claims

1-16. (canceled)

17. Device for producing a hollow body from a workpiece (1) in the shape of a circular blank, in particular a spinning and/or flow-forming machine, comprising characterized in that

a forming mandrel (11), which is supported in a rotationally driven manner about an axis of rotation (10),

a pressing element (18), which is supported about the axis of rotation (10) in a rotatable manner and in an axially displaceable manner relative to the forming mandrel (11) for clamping the workpiece (1), and

at least one forming roller (31), which can be fed axially and/or radially to the forming mandrel (11),

wherein on the pressing element (18) at least one forming die (40) is arranged, which can be displaced axially with respect to the pressing element (18) and can be moved axially relative to the forming mandrel (11) for forming the workpiece (1),

the device is adapted to draw the workpiece (1) into the forming die (40) through axial movement of the forming die (40) and/or the forming mandrel (11) and to thereby form the said workpiece.

18. Device according to claim 17, characterized in that the forming die (40) surrounds the pressing element (18) in a ring-like manner.

19. Device according to claim 17, characterized in that on the forming mandrel (11) and/or on the pressing element (18) a stamp (13) is arranged, which can be moved frontally out of the forming mandrel (11) or the pressing element (18) for carrying out a forming operation.

20. Device according to claim 17, characterized in that the forming die (40) has several die elements (41, 42) which can be moved axially relative to one another.

21. Method for producing a hollow body from a workpiece (1) in the shape of a circular blank by means of a device comprising a forming mandrel (11), which is supported in a rotationally driven manner about an axis of rotation (10), a pressing element (18), which is supported about the axis of rotation (10) in a rotatable manner and in an axially displaceable manner relative to the forming mandrel (11) for clamping the workpiece (1), and comprising at least one forming die (40), which is arranged on the pressing element (18) and can be displaced axially with respect to the pressing element (18) and which can be moved axially relative to the forming mandrel (11) for forming the workpiece (1), in particular by means of a device according to any one of claims 1 to 4, wherein characterized in that

an external portion (5) of the workpiece (1), which has been set into rotation, is formed, in particular projected formed, spun or flow-formed into a cylindrical shape (8) by feeding at least one forming roller (31),

through the deep drawing or pressing in a central portion (4) of the workpiece (1) a base portion of the hollow body is formed, in which case the workpiece (1) is drawn into the forming die (40) through axial movement of the forming die (40) and/or the forming mandrel (11) and is thereby formed.

22. Method according to claim 21, characterized in that the deep drawing or pressing of the central portion (4) and the folding-over of the external portion (5) are carried out in the same setting.

23. Method according to claim 21, characterized in that during the deep drawing or pressing the external portion (5) is left unformed or is formed in a funnel-like manner.

24. Method according to claim 21, characterized in that during the deep drawing or pressing the external portion (5) is supported in particular by means of at least one supporting roller (61, 62).

25. Method according to claim 21, characterized in that the portion of the cylindrical shape (8) of the workpiece (1) is stretch-formed in at least one roller pass.

26. Method according to claim 25, characterized in that during the stretch-forming a selected wall thickness distribution (28) is produced in an end portion (7) of the cylindrical shape (8), in particular by means of at least one multi-stage stretching roller (36) and/or through split adjustment.

27. Method according to claim 21, characterized in that after the forming and in particular after stretch-forming the end portion of the cylindrical shape (8) is drawn-in by feeding at least one draw-in roller (38) and is closed, in particular by forming a container neck.

28. Method according to claim 21, characterized in that during the deep drawing or pressing the wall thickness is changed in the central portion (4).

29. Method according to claim 21, characterized in that on the workpiece (1) in the shape of a circular blank an opening with a hub (2) is formed.

30. Method according to claim 21, characterized in that in particular after the deep drawing or pressing material is removed in the base portion by means of at least one roller and is formed to a flange.

31. Method according to claim 21, characterized in that the workpiece (1) is heated prior to the deep drawing or pressing.