EP4155001B1 - Method and devices for reforming a tubular hollow body - Google Patents

Description

• mit einer Umformmatrize, die zur Anordnung an der Außenseite des Hohlkörpers ausgebildet ist und die mit einer zur Aufnahme des Hohlkörpers ausgebildeten Matrizenöffnung versehen ist,
• mit einem Dorn, der zur Anordnung im Innern des Hohlkörpers ausgebildet ist und der an seinem Umfang mit einem formgebenden Dornprofil versehen ist mit Dornprofilvorsprüngen und zwischen den Dornprofilvorsprüngen ausgebildeten Dornprofilzwischenräumen, wobei an dem im Innern des Hohlkörpers angeordneten Dorn die Dornprofilvorsprünge und die Dornprofilzwischenräume längs der Hohlkörperachse verlaufen und sich die Dornprofilzwischenräume zu der achsparallelen Innenseite der Hohlkörperwand hin öffnen sowie
• mit einem Umformantrieb, der einen Matrizenantrieb aufweist, mittels dessen die Umformmatrize mit einer axialen Matrizenbewegung längs der Hohlkörperachse relativ zu dem Hohlkörper und dabei längs des im Innern des Hohlkörpers angeordneten Dorns bewegbar ist, wobei aufgrund der axialen Matrizenbewegung und eines damit verbundenen Überschreitens der Fließgrenze des Materials der Hohlkörperwand Material der Hohlkörperwand unter Ausbildung eines Innenprofils der Hohlkörperwand in die Dornprofilzwischenräume des Dorns fließt.

The invention relates to a device for forming a tubular hollow body, which has a hollow body wall made of a plastically deformable material and a hollow body axis running in the longitudinal direction of the hollow body.

• with a forming die which is designed to be arranged on the outside of the hollow body and which is provided with a die opening designed to receive the hollow body,
• with a mandrel which is designed to be arranged inside the hollow body and which is provided on its periphery with a shaping mandrel profile with mandrel profile projections and between the mandrel profile projections formed mandrel profile projections, wherein on the mandrel arranged inside the hollow body the mandrel profile projections and the mandrel profile spaces along the axis of the hollow body run and the mandrel profile gaps open towards the axis-parallel inside of the hollow body wall and
• with a forming drive, which has a die drive, by means of which the forming die can be moved with an axial die movement along the hollow body axis relative to the hollow body and thereby along the mandrel arranged inside the hollow body, whereby due to the axial die movement and an associated exceeding of the yield point of the Material of the wall of the hollow body Material of the wall of the hollow body flows into the mandrel profile interspaces of the mandrel, forming an inner profile of the wall of the hollow body.

• wobei die Anordnung eine erste Umformvorrichtung und eine zweite Umformvorrichtung umfasst und die zweite Umformvorrichtung der ersten Umformvorrichtung in einem Umformprozess nachgeordnet ist,
• wobei die erste Umformvorrichtung ausgebildet ist zur Erzeugung einer Vorform eines fertig umgeformten Hohlkörpers aus dem Hohlkörper in einem Ausgangszustand,
• wobei die Vorform als rohrartiger Hohlkörper mit einer Vorformwand aus einem plastisch verformbaren Werkstoff und mit einer mit der Hohlkörperachse zusammenfallenden Vorformachse ausgebildet ist und
• wobei die zweite Umformvorrichtung ausgebildet ist zur Erzeugung einer Folgeform der Vorform, insbesondere zur Erzeugung des fertig umgeformten Hohlkörpers, die eine Folgeformwand aufweist.

The invention also relates to an arrangement for forming a tubular hollow body, which has a hollow body wall made of a plastically deformable material and a hollow body axis running in the longitudinal direction of the hollow body,

• wherein the arrangement comprises a first forming device and a second forming device and the second forming device is arranged downstream of the first forming device in a forming process,
• wherein the first forming device is designed to produce a preform of a completely formed hollow body from the hollow body in an initial state,
• wherein the preform is designed as a tubular hollow body with a preform wall made of a plastically deformable material and with a preform axis that coincides with the axis of the hollow body and
• wherein the second forming device is designed to produce a subsequent mold of the preform, in particular to produce the finished formed hollow body, which has a subsequent mold wall.

Furthermore, the invention relates to methods that can be carried out with the aforementioned device and with the aforementioned arrangement for shaping a tubular hollow body which has a hollow body wall made of a plastically deformable material and a hollow body axis running in the longitudinal direction of the hollow body.

For example, in the production of hollow shafts for motor vehicles, shaft blanks made of plastically deformable metallic materials are to be provided with external and/or internal teeth and, in particular, to be reduced in their diameter and/or in their wall thickness over partial lengths. A common manufacturing method for producing toothings on shaft blanks is axial forming using a forming tool that includes a forming die that encloses the shaft blank on the outside and a mandrel that supports the shaft blank on the inside. Depending on the application, the forming die and/or the mandrel is provided with shaping teeth. A common manufacturing process for reducing the diameter and/or wall thickness of shaft blanks is drawing-in.

Generic prior art is disclosed in DE 10 2019 103 926 A1 .

This document relates to a tool and a method for axially forming a tube. The tool comprises an annular die guided on the outside of the tube and a mandrel guided inside the tube. At the same time as the wall thickness is reduced, the pipe wall is provided with internal teeth Mistake. A mandrel with a gear-shaped cross-section is used to produce the internal teeth on the pipe wall. In the spaces between the teeth on the mandrel, the teeth of the internal toothing are formed by the material of the pipe wall, which is plasticized as a result of the forming process.

The object of the present invention is to provide devices and methods by means of which a tubular hollow body can be provided with internal teeth of high quality.

According to the invention, this object is achieved by the device according to patent claim 1, the arrangement according to patent claim 8 and the methods according to patent claims 14 and 16.

In the case of the invention, a forming tool is used to produce an internal toothing on a tubular hollow body made of a preferably metallic material and with a preferably circular cross section, which has a forming die with a profiled die opening and a mandrel with a profiled circumference. The fact that the forming die and the mandrel are rotated about the axis of the hollow body to be formed relative to one another in such a way that the die profile projections of the forming die arranged on one side of the hollow body wall and the mandrel profile gaps arranged on the other side of the hollow body wall are opposite one another in the radial direction of the hollow body axis is essential to the invention . Due to the mutual positioning of the die profile projections and the mandrel profile spaces according to the invention, the die profile projections cause the mandrel profile spaces to be completely filled with plasticized material of the hollow body wall during the forming process and, under certain circumstances, also compress the wall material that has flowed into the mandrel profile spaces. As a result, the mandrel, whose profile reflects the target geometry of the inner profile of the hollow body wall to be created as a negative, produces the inner profile of the hollow body wall with an actual geometry that at most deviates minimally from the target geometry and which consequently has an extraordinarily high quality.

According to the invention, the inner profile of the hollow body wall can be produced in a single-stage or in a multi-stage process.

By means of the forming device according to patent claim 1 and according to the method according to patent claim 14, the wall of the hollow body is provided in one step with an inner profile with a desired geometry.

By means of the arrangement according to patent claim 8 and the method according to patent claim 16, the creation of the inner profile with the desired geometry is distributed over a number of method stages.

In the first stage of the method, a preform of the finished formed hollow body is produced from the hollow body in the initial state by means of a first forming device. The inner profile of the preform is then optimized.

The optimization of the inner profile of the preform wall follows in at least one further process step, in which the inner profile of a subsequent form of the preform, in particular the inner profile of the finished formed hollow body, is produced from the inner profile of the preform wall by means of a further forming device.

According to the invention, an arrangement with two forming devices for carrying out a two-stage forming process is preferred as a multi-stage arrangement. In this case, the finished formed hollow body with the target geometry of the inner profile on the wall of the hollow body is produced directly from the preform as a subsequent form.

In the case of the devices and methods according to the invention, the axial die movement can be carried out as a continuous movement in the forming direction but also as a movement with alternately executed long strokes in the forming direction and short return strokes in the opposite direction ("recursive axial forming").

Special embodiments of the devices and methods according to the independent patent claims 1, 8, 14 and 16 result from the dependent patent claims 2 to 7, 9 to 13 and 15.

The measures of the dependent patent claims 2 to 7 can also be provided in a corresponding manner in the case of the arrangement according to the invention with a plurality of forming devices and for carrying out a multi-stage forming process.

According to patent claim 2, in a preferred embodiment of the invention, internal teeth are created as the internal profile on the wall of the hollow body.

According to the invention, when the inner profile of the hollow body wall is created, the size of the hollow body cross section, which extends perpendicular to the hollow body axis, can remain unchanged.

In this case, a profiled forming die is used on the device according to the invention according to claim 1 with a die profile whose base line in the vertical projection onto the end face of the hollow body wall in the initial state lies outside the hollow body wall or coincides with the outside of the hollow body wall. The head line of the matrix profile lies in the vertical projection onto the end face of the hollow body wall in the initial state in an area that can extend from the interior of the hollow body wall to the interior of the cavity of the hollow body.

In the case of applications in which a forming die, which has a circular die opening with shaping teeth, is used to form a cylindrical hollow body, the root circle of the die teeth provided as the root line has a root circle diameter that is larger than or just as large as the outer diameter of the one to be formed Hollow body in the initial state. The diameter of the tip circle of the die teeth is smaller than the outer diameter of the cylindrical hollow body in the initial state.

The relationships between types of construction of the multi-stage arrangement according to the invention are corresponding, in the case of which a preform with unchanged Cross-sectional size and / or by means of the second forming device from the preform, a subsequent form is made with an unchanged cross-sectional size.

In a preferred embodiment of the invention, the device according to the invention and the arrangement according to the invention as well as the methods according to the invention are designed in such a way that the creation of the inner profile of the hollow body wall or the preform wall and/or the subsequent mold wall is accompanied by a reduction in the cross section of the hollow body or the preform (claims 13, 15 ).

• eine Reduzierung ausschließlich des Hohlraumquerschnitts des umzuformenden Hohlkörpers beziehungsweise der umzuformenden Vorform (im Falle von zylindrischen Rohren des Innendurchmessers des Rohres) bei unveränderter Dicke der Hohlkörperwand beziehungsweise der Vorformwand oder
• eine Reduzierung ausschließlich der Dicke der Hohlkörperwand beziehungsweise der Vorformwand bei unverändertem Hohlraumquerschnitt des Hohlkörpers beziehungsweise der Vorform oder
• eine Reduzierung sowohl des Hohlraumquerschnitts des umzuformenden Hohlkörpers beziehungsweise der umzuformenden Vorform als auch der Dicke der Hohlkörperwand beziehungsweise der Vorformwand.

A cross-sectional reduction in the sense of the invention is to be understood

• a reduction exclusively in the cavity cross-section of the hollow body to be formed or the preform to be formed (in the case of cylindrical tubes, the inner diameter of the tube) with the thickness of the hollow body wall or the preform wall remaining unchanged, or
• a reduction exclusively in the thickness of the hollow body wall or the preform wall with an unchanged cavity cross-section of the hollow body or the preform, or
• a reduction in both the cavity cross-section of the hollow body to be formed or the preform to be formed and the thickness of the hollow body wall or the preform wall.

For a reduction in the cross section of the hollow body by reducing the thickness of the hollow body wall, a design of the device according to the invention or the arrangement according to the invention is designed in which the common cross section of the mandrel and the hollow body wall in the initial state is larger than the opening cross section of the die opening or in the case of which the common cross section of the first mandrel and the wall of the hollow body is larger in the initial state than the opening cross-section of the first die opening and/or in the case of which the common cross-section of the second mandrel and the preform wall is larger in the initial state than the opening cross-section of the second die opening.

According to claim 3, a stationary axial abutment is provided for the hollow body in a further embodiment of the invention, on which the hollow body is supported when acted upon by the forming die in the direction of the axial die movement.

The device according to patent claim 4 and the forming process carried out with this device are provided for applications in which there is a risk of compression phenomena occurring on the hollow body to be formed due to the axial die movement.

In order to avoid compression of the hollow body, the forming drive has a mandrel drive in addition to the die drive. By means of the die drive, the forming die arranged on the outside of the hollow body is actively moved along the axis of the hollow body with the axial movement of the die. Due to the active movement of the forming die relative to the hollow body, the wall of the hollow body acted upon by the forming die is actively subjected to pressure by the forming die in the direction of the axial movement of the die. At the same time, the wall of the hollow body is subjected to tensile stress in the direction of the axial movement of the die as a result of the axial movement of the mandrel in the opposite direction to the axial movement of the die.

The active axial mandrel movement and the active axial die movement of the forming die arranged on the outside of the hollow body are superimposed on one another by means of the drive control of the forming drive according to the invention. Due to the superimposition of the two movements mentioned, the compressive stresses that build up in the wall of the hollow body due to the action of the forming die across the wall cross-section are at least partially compensated by the tensile stresses in the wall of the hollow body as a result of the active axial movement of the mandrel.

With a corresponding, for example empirical dimensioning and mutual coordination of the compressive stress on the hollow body by the forming die and the tensile stress on the hollow body by the mandrel, an undesirable Upsetting of the wall of the hollow body on the side of the forming die acting on the wall of the hollow body that is in the direction of the axial movement of the die is at least largely avoided, even without additional reinforcement of the hollow body. At the same time, high forming speeds can be achieved as a result of the superimposition of the active die movement and the active mandrel movement.

In general, both the axial mandrel movement and the axial die movement can be both position and force controlled.

The forming speed of the device according to the invention and the method according to the invention is largely independent of the material strength of the hollow body to be formed. With high-strength materials, relatively high forming forces are required, but at the same time the tendency of hollow bodies made of high-strength materials to buckle is relatively low. Conversely, tube-like hollow bodies made of low-strength materials tend to compress relatively strongly, but a reduction in the cross section of such hollow bodies is possible with relatively low forming forces.

According to patent claim 5, in the case of the invention, the ratio of the speeds of the axial mandrel movement and the axial die movement of the forming die arranged on the outside of the hollow body is determined by means of the drive control of the forming drive, depending on the ratio of the size of the cross section of the hollow body in the initial state and the cross-sectional size of the hollow body set after the forming process. Particularly in the case of a cross-section reduction, the speed of the axial die movement of the forming die arranged on the outside of the hollow body can be greater, but also less than the speed of the axial movement of the mandrel. As part of an experimental application of the invention, high-quality machining results could be achieved at a die speed of 30 mm/s to 60 mm/s and a mandrel speed of 21 mm/s to 43 mm/s.

According to claim 6, a further embodiment of the invention provides that the ratio of the amounts of the axial mandrel movement and the axial die movement during the forming process is reciprocal to the ratio of the speeds of the axial mandrel movement and the axial die movement during the forming process. This ensures that the active mandrel and forming die movements carried out to form a hollow body over a forming length end simultaneously when the forming length is reached, despite different speeds of the mandrel and the forming die.

Patent claim 7 provides in a further advantageous embodiment of the invention that the forming die can be moved by means of the die drive with a positioning movement from a position away from the hollow body to be formed into a position in which the forming die is arranged on the outside of the hollow body and that by means of the drive control of the Device drive the die drive and the mandrel drive are controlled in such a way that the mandrel drive initiates the axial mandrel movement before the forming die acts on the hollow body wall due to the positioning movement. When the forming die comes into contact with the hollow body to be formed for the first time, the mandrel and the hollow body, which is driven by it along the axis of the hollow body and is subjected to tensile stress during the forming process, are therefore already in motion. The positioning movement of the forming die is preferably carried out in the direction of the axial movement of the die.

To carry out the multi-stage forming process, forming devices can be used whose mandrels have mandrel profile gaps with gap cross sections of different sizes. The inner profile with the desired geometry is preferably produced from the inner profile of the preform by means of the second mandrel. In this case, wall material is fed through the second forming die to the profile projections of the inner profile of the preform produced in the mandrel profile gaps of the first forming die. Accordingly, the first mandrel interstices of the first mandrel have less wall material to accommodate than the second mandrel interstices of the second mandrel. If, at the same time, the cross section of the first mandrel profile gaps is larger than the cross section of the second mandrel profile gaps, the first mandrel profile gaps are oversized compared to the inner profile of the preform created on the first mandrel profile, as a result of which the first mandrel and the preform with relatively can be separated from each other with little effort.

In a preferred embodiment of the invention, the geometry of the first shaping mandrel profile of the first mandrel and the second shaping mandrel profile of the second mandrel match (patent claim 9). In this way it can be ensured to a particular degree that the forming process carried out by means of the second mandrel leads to an optimization of the inner profile produced by means of the first mandrel. The geometry of the inner profile created by means of the first mandrel is brought into line with the target geometry specified by the identical mandrel profile or at least brought closer to the target geometry on the second forming device by means of the second forming die and the second mandrel interacting with it.

Processing results of particularly high quality can be achieved if the same mandrel is used in the second process step as in the first process step (claim 10). In this case, the mandrel can remain inside the then existing preform after the end of the first process step. Consequently, the processing of the preform by the second forming device does not have to be preceded by a mandrel change on the preform that may impair the processing quality.

According to patent claim 11, the first forming die of the multi-stage forming arrangement in a further development of the invention has a die opening with a smooth wall. The inventively optimized filling of the interstices of the mandrel profile with plasticized material of the hollow body wall accordingly takes place exclusively in the second process step of the forming process according to the invention.

Deviating from this, in the case of the inventive design according to patent claim 12, provisions for an optimized filling of the mandrel profile gaps with plasticized material of the hollow body wall are already taken at the first forming device of the multi-stage arrangement.

Figur 1

ein umzuformendes Rohr in einem Ausgangszustand,

Figur 2

eine einstufige Vorrichtung zum Umformen des Rohres gemäß Figur 1 in einem einstufigen Umformverfahren mit einer Querschnittsreduzierung und mit einer Profilierung der Rohrwand,

Figur 3a

eine erste Umformvorrichtung einer zweistufigen Umformanordnung zur Erzeugung einer Vorform eines fertig umgeformten Rohres im Rahmen eines zweistufigen Umformverfahrens,

Figur 3b

eine zweite Umformvorrichtung der zweistufigen Umformanordnung zur Erzeugung des fertig umgeformten Rohres aus der Vorform gemäß Figur 3a im Rahmen des zweistufigen Umformverfahrens und

Figur 4

eine einstufige Vorrichtung zum Umformen des Rohres gemäß Figur 1 in einem einstufigen Umformverfahren mit einer Profilierung der Rohrwand aber ohne Querschnittsreduzierung der Rohrwand.

The invention is explained in more detail below using exemplary schematic representations. Show it:

figure 1

a tube to be formed in an initial state,

figure 2

according to a one-stage device for forming the tube figure 1 in a single-stage forming process with a cross-section reduction and with a profiling of the tube wall,

Figure 3a

a first forming device of a two-stage forming arrangement for producing a preform of a finished formed tube as part of a two-stage forming process,

Figure 3b

a second forming device according to the two-stage forming arrangement for producing the finished formed tube from the preform Figure 3a as part of the two-stage forming process and

figure 4

according to a one-stage device for forming the tube figure 1 in a single-stage forming process with profiling of the tube wall but without reducing the cross-section of the tube wall.

According to figure 1 a tube 1 made of a plastically deformable metallic material is provided as the hollow body to be shaped. The tube 1 has a tube wall 2 as the hollow body wall and a tube axis 3 running in the longitudinal direction of the tube 2 as the hollow body axis. The tube 1 is cylindrical with a frontal view of the tube 1 in figure 1 recognizable circular tube cross-section 4 as a hollow body cross-section and with an annular wall cross-section.

A steering shaft for a motor vehicle is to be manufactured from the tube 1 .

For this purpose, in figure 2 and figure 4 illustrated single-stage devices 5, 5a or alternatively in the Figures 3a and 3b shown multi-stage, in the example shown two-stage arrangement 6 used. The two-stage arrangement 6 comprises a first forming device 7 and a second forming device 8.

The devices 5, 5a and the forming devices 7, 8 with the respectively formed workpieces are in figure 2 and in the Figures 3a, 3b and 4 shown in each case in a highly schematic side view and also in a view of the end face on the right in the side view.

The device 5 according to figure 2 is mounted on an axial forming machine of conventional design, for example an axial forming machine such as that sold by FELSS Systems GmbH, 75203 Koenigsbach-Stein, Germany under the product name "Aximus".

A forming die 9 of the device 5 designed to be arranged on the outside of the tube 1 is installed in a tool holder of the axial forming machine that can be moved along the tube axis 3 . A mandrel holder of the axial forming machine, which can also be moved along the tube axis 3, is used to fix a mandrel 10 of the device 5. The tool holder for the forming die 9 and the mandrel holder for the mandrel 10 are in figure 2 not shown for the sake of simplicity.

The forming die 9 has a die opening 11 (“calibration section”) designed to accommodate the pipe 1 . At the die opening 11 the forming die 9 is provided with a shaping die profile in the form of shaping die teeth 12 . The die toothing 12 has die teeth 13 as die profile projections and die tooth gaps 14 formed between the die teeth 13 as die profile gaps. The root circle diameter of the die opening 11 is smaller than the diameter of the pipe cross section 4 in the initial state with the pipe 1 not yet deformed.

The mandrel 10 is designed to be arranged inside the tube 1 and is provided on its circumference with a shaping mandrel profile designed as a shaping mandrel toothing 15 . The shaping mandrel toothing 15 is formed by mandrel profile projections in the form of mandrel teeth 16 and mandrel tooth spaces 17 arranged between the mandrel teeth 16 as mandrel profile spaces.

On the forming die 9 seated on the outside of the tube 1, the die teeth 13 and the spaces between the teeth 14 run along the axis of the tube 3. The spaces between the teeth 14 open towards the outside of the tube wall 2 parallel to the axis.

On the mandrel 10 inside the tube 1, the mandrel teeth 16 and the mandrel tooth gaps 17 also run along the tube axis 3. The mandrel tooth gaps 17 open towards the inside of the tube wall 2 parallel to the axis.

The forming die 9 and the mandrel 10 are positioned relative to each other around the tube axis 3 in such a way that the die teeth 13 arranged on the axis-parallel outside of the tube wall 2 and the mandrel tooth gaps 17 arranged on the axis-parallel inside of the tube wall 2 as well as those on the axis-parallel outside of the tube wall 2 arranged matrix tooth interspaces 14 and arranged on the axis-parallel inside of the tube wall 2 mandrel teeth 16 each opposite each other on the tube wall 2 in the radial direction of the tube axis 3.

By means of the device 5, the tube cross-section 4, specifically the wall thickness of the tube wall 2, is reduced and at the same time the tube wall 2 is provided on the inside with an internal profile in the form of internal teeth 18.

A die drive 19 of a forming drive 20 of the device 5 is used to generate the axial die movement of the forming die 9 required for this purpose. In addition to the die drive 19, the forming drive 20 includes a mandrel drive 21 and a drive controller 22.

At the beginning of the forming process, the die drive 19 moves the tool holder of the axial forming machine together with the forming die 9 along the pipe axis 3 until the forming die 9 moves from a position away from the pipe 1 to the in figure 1 right end of the tube 1 and this tube end of the tube-side mouth of the die opening 11 is immediately adjacent. At this point in time, the tube 1 is still in its undeformed initial state.

In addition, the mandrel drive 21 moves the mandrel holder of the axial forming machine with the mandrel 10 along the pipe axis 3, starting from a position in figure 1 left of the tube 1 to the right until the fixed to the mandrel holder mandrel 10 inside the tube 1, the position according to figure 2 takes.

The tube 1 to be formed is on the axial forming machine with its in the Figures 1 and 2 left end on a stationary axial abutment 23 along the tube axis 3 .

To form the pipe 1, the forming die 9 is now moved by means of the die drive 19, starting from its starting position at the right-hand end of the pipe 1, with an axial die movement relative to the pipe 1 supported on the stationary axial abutment 23 and consequently also stationary in the direction of the stationary axial abutment 23 moves. During the axial die movement, the forming die 9 moves along the tube axis 3 relative to the tube 1 and also along the mandrel 10 arranged inside the tube 1. The direction of movement of the forming die 9 during the axial die movement is in figure 2 illustrated by an arrow 24 .

Due to the oversize of the non-deformed tube cross-section 4 compared to the opening cross-section of the die opening 11, the axial die movement of the forming die 9 causes the yield point of the material of the tube wall 2 to be exceeded on the side of the forming die 9 in the direction of arrow 24. The tube cross-section 4 is reduced due to the axial movement of the die and material of the tube wall 2 flows into the spaces 17 between the mandrel teeth of the mandrel 10, forming the internal teeth 18 of the tube wall 2 and at the same time lengthening of the tube wall 2.

The die teeth 13 of the die toothing 12, due to their arrangement opposite the mandrel tooth interspaces 17 of the mandrel 10, ensure that the mandrel tooth interspaces 17 are completely filled with the flowing material of the tube wall 2 and the internal toothing 18 of the tube wall 2 consequently exactly with its specified by the mandrel toothing 15 Target geometry is generated.

In figure 2 a point in time of the forming process is illustrated at which the processing of the pipe 1 has not yet been completed and the forming die 9 consequently still has a remaining distance to cover in the direction of the axial abutment 23 .

If, in the case of tube 1, there is a risk of the tube 1 being compressed during the forming process, for example due to the length of the tube, the above kinematics of the forming process are modified.

Deviating from the processes described above, in order to avoid upsetting of the tube 1, the axial die movement of the forming die 9 is controlled by the drive control 22 in the opposite direction to the axial die movement and in the direction of an arrow 25 in figure 2 executed axial mandrel movement of the mandrel 10 superimposed.

The speeds of the axial movement of the die and the axial movement of the mandrel can be dimensioned differently. For example, by means of the drive control 22, the speed of the axial die movement of the forming die 9 in the direction of the arrow 24 to 60 mm/s and the speed of the axial mandrel movement of the mandrel 10 in the direction of the arrow 25 can be set to 15 mm/s.

When the free end of the tube 1 enters the die opening 11 at the beginning of the forming process, the tube wall 2 is pressed against the mandrel 10 in the relevant area. This creates a frictional connection between the tube wall 2 and the mandrel 10 .

At the same time, the pipe wall 2 is subjected to pressure due to the axial movement of the die by the forming die 9 on its side in the direction of the arrow 24 and the yield point of the material of the pipe wall 2 is thereby exceeded. The axial abutment 23, which supports the tube 1 acted upon by the forming die 9, is stationary along the tube axis 3 even with mutual superimposition of an axial die movement and an axial mandrel movement during the actuation of the tube 1 by the forming die 9.

As a result of the frictional connection between the tube wall 2 and the mandrel 10 , the tube wall 2 acted upon on the outside by the forming die 9 is subjected to tensile stress by means of the mandrel 10 in the direction of the arrow 25 . The mandrel 10 driven by the mandrel drive 21 consequently actively pulls the pipe wall 2 in the direction of the arrow 25 through the die opening 11 and the thickness of the pipe wall 2 is reduced while at the same time the pipe 1 is lengthened and the internal teeth 18 are produced on the pipe wall 2.

Due to a corresponding coordination of the axial die movement in the direction of arrow 24 and the axial mandrel movement in the direction of arrow 25, i.e. by appropriate control of the die drive 19 and the mandrel drive 21 by means of the drive control 22, the tube wall 2 is formed without the in the direction of the arrow 24 located side of the forming die 9 to a compression of the tube 1 comes. As a result, in the case of the device 5, no additional reinforcement is required on the outside of the tube 1 in order to prevent the tube 1 from being compressed.

Appropriate control of the die drive 19 and the mandrel drive 21 ensures that when the desired forming length is reached on the tube 1, the die drive 19 and the mandrel drive 21 can be shut down simultaneously.

Due to the fact that an axial die movement and a counter-rotating axial mandrel movement are carried out at the same time, a high forming speed can be achieved. Irrespective of the high forming speed, a high-quality machining result is obtained on the tube 1.

While using the devices 5, 5a according to figure 2 and according to figure 4 the internal toothing on the pipe wall 2 is produced in a one-step forming process, which is used in the Figures 3a and 3b shown arrangement 6 with the first forming device 7 and the second forming device 8 for carrying out a two-stage forming process.

The first forming device 7 of the arrangement 6 ( Figure 3a ) comprises a first forming die 26 for placement on the outside of the tube 1 and a first mandrel 27 for placement inside the tube 1.

The first forming die 26 of the first forming device 7 is designed with a first die opening 28 for receiving the pipe 1 . In the example shown, the first die opening 28 has smooth walls. The diameter of the first die opening 28 corresponds to the root diameter of the toothed die opening 11 on the forming die 9 according to FIG figure 2 and is consequently also smaller than the diameter of the pipe cross section 4 of the pipe 1 in the undeformed initial state.

The first mandrel 27 of the first forming device 7 has a first shaping mandrel toothing 29 on its circumference as the first shaping mandrel profile, with first mandrel profile projections in the form of first mandrel teeth 30 and first mandrel tooth gaps 31 formed between the first mandrel teeth 30 as first mandrel profile gaps. The first mandrel teeth 30 and the first mandrel tooth spaces run on the first mandrel 27 arranged inside the pipe 1 31 along the tube axis 3. The first mandrel tooth gaps 31 open towards the inside of the tube wall 2 parallel to the axis. The toothing geometry of the toothed first mandrel 27 of the first forming device 7 forms the target geometry of the toothed inside of the pipe wall 2 on the finished formed pipe.

In a first stage of the two-stage forming process, a preform 32 of the finished formed tube is produced from the undeformed tube 1 in the initial state.

The sequences of the first process stage of the two-stage forming process correspond in principle to the sequences of the single-stage forming process described in detail above figure 2 .

A first die drive 33 of a first forming drive 34 of the first forming device 7 generates an axial die movement of the first forming die 26 seated on the tube 1 relative to the tube 1 along the tube axis 3 and along the first mandrel 27 arranged inside the tube 1.

If there is a risk of compression, the axial die movement of the first forming die 26 is superimposed by an axial mandrel movement of the first mandrel 27 which is carried out by means of a first mandrel drive 35 of the forming drive 34 and runs in the opposite direction to the axial die movement of the first forming die 26 . The active axial die movement of the first forming die 26 and the active axial mandrel movement of the first mandrel 27 are optionally controlled in a coordinated manner by a first drive controller 36 of the first forming drive 34 .

The product of the first stage of the two-stage forming process is the preform 32 of the finished formed tube with a preform axis 37 coinciding with the tube axis 3 and a preform wall 38. The wall thickness of the preform wall 38 is reduced compared to the wall thickness of the tube wall 2. In addition, the preform wall 38 is provided with an internal profile in the form of internal teeth 39 .

Since the geometry of the internal toothing 39 on the preform wall 38 still has too large a tolerance compared to the target geometry of the finished formed tube, the first method step according to FIG Figure 3a the second stage of the two-stage forming process carried out by means of the second forming device 8.

According to Figure 3b the second forming device 8 comprises a second forming die 40 to be arranged on the outside of the preform 32 and a second mandrel 41 to be arranged inside the preform 32.

A second die opening 42 of the second forming die 40 is designed to receive the preform 32 and has a shaping die toothing 43 on the opening wall as a shaping die profile. The shaping die toothing 43 is formed by die profile projections in the form of die teeth 44 and die tooth gaps 45 formed between the die teeth 44 as die profile gaps.

When the second forming die 40 is arranged on the outside of the preform 32, the die teeth 44 and the die tooth gaps 45 run along the preform axis 37. The die tooth gaps 45 open towards the axis-parallel outside of the preform wall 38. The root circle diameter of the die teeth 43 on the second die opening 42 of the second forming die 40 corresponds to the diameter of the smooth-walled first die opening 28 on the first forming die 26 of the first forming device 7.

The second mandrel 41 of the second forming device 8 is structurally identical to the first mandrel 27 of the first forming device 7.

The second mandrel 41 has a second shaping mandrel toothing 46 on its circumference as a second shaping tooth profile, with second mandrel profile projections in the form of second mandrel teeth 47 and with second mandrel profile spaces in the form of second mandrel tooth spaces 48. The second shaping mandrel toothing 46 also forms the teeth on the finished formed Pipe internal gearing to be created with its target geometry.

On the second mandrel 41 arranged inside the preform 32, the second mandrel teeth 47 and the second mandrel tooth gaps 48 run along the preform axis 37. The second mandrel tooth gaps 48 open towards the inside of the preform wall 38 parallel to the axis.

The second forming die 40 and the second mandrel 41 are arranged relative to one another around the preforming axis 37 in such a way that the die teeth 44 arranged on the axis-parallel outside of the preform wall 38 and the second mandrel tooth gaps 48 arranged on the axis-parallel inside of the preform wall 38 as well as those on the axis-parallel outside the preform wall 38 and the second mandrel teeth 47 arranged on the inner side of the preform wall 38 parallel to the axis are opposite one another on the preform wall 38 in the radial direction of the preform axis 37 . At the beginning of the second stage of the forming process, the gaps between the mandrel teeth 48 accommodate the inner profile 39 of the preform 32 produced in the first stage of the process.

The sequences of the second method stage of the two-stage forming process also correspond in principle to the sequences of the one-stage forming process carried out by means of the device 5 according to FIG figure 2 .

A second die drive 49 of a second forming drive 50 moves the second forming die 40 seated on the preform 32 with an axial die movement relative to the preform 32 along the preforming axis 37 and along the second mandrel 41 arranged inside the preform 32.

If there is a risk of compression, the axial die movement of the second forming die 40 is superimposed by an opposing axial mandrel movement of the second mandrel 41 generated by means of a second mandrel drive 51 . The second die drive 49 and the second mandrel drive 51 are controlled in a coordinated manner by a second drive controller 52 of the second forming drive 50 .

During the second stage of the process, the die teeth 44 of the die toothing 43 on the second forming die 40, due to their arrangement in relation to the second mandrel tooth gaps 48 of the second mandrel 41, ensure that that the second mandrel tooth interspaces 48 are completely filled with the flowing material of the preform wall 38 and that consequently an internal toothing 53 results as an internal profile on the finished formed tube, the geometry of which corresponds exactly to the target geometry specified by the second mandrel toothing 46.

Just like the device 5 according to figure 2 and also the forming devices 7, 8 according to the Figures 3a, 3b is also the device 5a according to FIG figure 4 mounted on an axial forming machine of conventional design.

A forming die 9a of the device 5a has a die opening 11a (“calibration section”) designed to accommodate the pipe 1 . At the die opening 11a, the forming die 9a is provided with a shaping die profile in the form of shaping die teeth 12a. The die toothing 12a has die teeth 13a as die profile projections and die tooth gaps 14a formed between the die teeth 13a as die profile gaps.

Deviating from the forming die according to 9 figure 2 the root circle diameter of the die teeth 12a on the forming die 9a is greater than the outer diameter of the tube 1 in the initial state with the tube 1 still undeformed. The tip circle diameter of the die teeth 12a is slightly smaller than the inner diameter of the tube 1 in the initial state.

A mandrel 10a is designed to be arranged inside the tube 1 and is provided on its circumference with a shaping mandrel profile designed as a shaping mandrel toothing 15a. The shaping mandrel toothing 15a is formed by mandrel profile projections in the form of mandrel teeth 16a and mandrel tooth spaces 17a arranged between the mandrel teeth 16a as mandrel profile spaces.

On the forming die 9a seated on the outside of the tube 1, the die teeth 13a and the spaces between the teeth 14a run along the axis of the tube 3. The spaces between the teeth 14a open towards the outside of the tube wall 2 parallel to the axis.

On the mandrel 10a inside the tube 1, the mandrel teeth 16a and the spaces between the mandrel teeth 17a also run along the tube axis 3. The spaces between the mandrel teeth 17a open towards the inside of the tube wall 2, which is parallel to the axis.

The forming die 9a and the mandrel 10a are positioned relative to each other around the tube axis 3 in such a way that the die teeth 13a arranged on the axis-parallel outside of the tube wall 2 and the mandrel tooth gaps 17a arranged on the axis-parallel inside of the tube wall 2 as well as the spaces on the axis-parallel outside of the tube wall 2 arranged matrix tooth interspaces 14a and arranged on the axis-parallel inside of the tube wall 2 mandrel teeth 16a are opposite each other on the tube wall 2 in the radial direction of the tube axis 3.

Due to the dimensioning of the addendum and root circle diameters on the die toothing 12a, the device 5a produces an internal profile in the form of internal toothing 18a on the inside of the tube wall 2, without the wall thickness of the tube wall 2 being reduced in the process.

The procedures during the forming of the tube 1 by means of the device 5a also correspond to the procedures on the device 5 according to FIG figure 2 .

A die drive 19a of a forming drive 20a of the device 5a is used to generate an axial die movement of the forming die 9a. In addition to the die drive 19a, the forming drive 20a includes a mandrel drive 21a and a drive controller 22a.

To form the pipe 1, the forming die 9a is moved by means of the die drive 19a, starting from its starting position at the right-hand end of the pipe 1, with an axial die movement relative to the pipe 1 supported on the stationary axial abutment 23 and consequently also stationary in the direction of the stationary axial Abutment 23 moves. During the axial movement of the die, the forming die 9a moves in the direction of the arrow 24 along the tube axis 3 relative to the tube 1 and also along the mandrel 10a arranged inside the tube 1.

Due to the oversize of the undeformed tube wall 2 compared to the tip circle diameter of the die toothing 12a, material of the tube wall 2 flows into the mandrel tooth gaps 17a of the mandrel 10a, forming the internal toothing 18a of the tube wall 2.

The die teeth 13a of the die toothing 12a also ensure, due to their arrangement opposite the mandrel tooth interspaces 17a of the mandrel 10a, that the mandrel tooth interspaces 17a are completely filled with the flowing material of the tube wall 2 and the internal toothing 18a of the tube wall 2 consequently exactly with its predetermined by the mandrel toothing 15a Target geometry is generated.

Claims (16)

1. A device for forming a tubular hollow body (1) having a hollow body wall (2) made from a plastically deformable material and a hollow body axis (3) extending in the longitudinal direction of the hollow body (1),

   • having a forming die (9, 9a) designed to be arranged on the outer side of the hollow body (1) and provided with a die opening (11, 11a) designed for receiving the hollow body (1),

   • having a mandrel (10, 10a) designed to be arranged in the interior of the hollow body (1) and provided on its circumference with a shape-imparting mandrel profile (15, 15a) having mandrel profile projections (16, 16a) and mandrel profile intermediate spaces (17, 17a) formed between the mandrel profile projections (16, 16a), with the mandrel profile projections (16, 16a) and the mandrel profile intermediate spaces (17, 17a) extending along the hollow body axis (3) on the mandrel (10, 10a) arranged in the interior of the hollow body (1), and the mandrel profile intermediate spaces (17, 17a) opening towards the axially parallel inner side of the hollow body wall (2), and

   • having a forming drive (20, 20a) with a die drive (19, 19a), by means of which the forming die (9, 9a) can be moved with an axial die movement along the hollow body axis (3) relative to the hollow body (1) and thereby along the mandrel (10, 10a) arranged in the interior of the hollow body (1), wherein material of the hollow body wall (2) flows into the mandrel profile intermediate spaces (17, 17a) of the mandrel (10, 10a) due to the axial die movement and an associated exceeding of the flow limit of the material of the hollow body wall (2), forming an inner profile (18, 18a) of the hollow body wall (2),
   characterized in that the forming die (9, 9a) is provided on the die opening (11, 11a) with a shape-imparting die profile (12, 12a) having die profile projections (13, 13a) and die profile intermediate spaces (14, 14a) formed between the die profile projections (13, 13a), when the forming die (9, 9a) is moved with the axial die movement

   • the die profile projections (13, 13a) and the die profile intermediate spaces (14, 14a) extending along the hollow body axis (3) and the die profile intermediate spaces (14, 14a) opening towards the axially parallel outer side of the hollow body wall (2) and

   • die profile projections (13, 13a) arranged on the axially parallel outer side of the hollow body wall (2) and mandrel profile intermediate spaces (17, 17a) arranged on the axially parallel inner side of the hollow body wall (2) as well as die profile intermediate spaces (14, 14a) arranged on the axially parallel outer side of the hollow body wall (2) and mandrel profile projections (16, 16a) arranged on the axially parallel inner side of the hollow body wall (2) in each case lying opposite to each other on the hollow body wall (2) in the radial direction of the hollow body axis (3), with the die profile projections (13, 13a) impinging material of the hollow body wall (2) in the direction of the mandrel profile intermediate spaces (17, 17a) opposite the die profile projections (13, 13a) to form the inner profile (18, 18a) of the hollow body wall (2).
2. The device according to claim 1, characterized in that

   • a mandrel-side toothed profile having mandrel teeth as mandrel profile projections (16, 16a) and having mandrel tooth intermediate spaces as mandrel profile intermediate spaces (17, 17a) is provided as a shape-imparting mandrel profile (15, 15a), and

   • a die-side toothed profile having die teeth as die profile projections (13, 13a) and having die tooth intermediate spaces as die profile intermediate spaces (14, 14a) is provided as a shape-imparting die profile (12, 12a),
   die teeth arranged on the axially parallel outer side of the hollow body wall (2) and mandrel tooth intermediate spaces arranged on the axially parallel inner side of the hollow body wall (2) as well as die tooth intermediate spaces arranged on the axially parallel outer side of the hollow body wall (2) and mandrel teeth arranged on the axially parallel inner side of the hollow body wall (2) in each case lying opposite to each other on the hollow body wall (2) in the radial direction of the hollow body axis (3) and the die teeth impinging material of the hollow body wall (2) in the direction of the mandrel tooth intermediate spaces opposite the die teeth to form the inner profile (18, 18a) of the hollow body wall (2).
3. The device according to any of the preceding claims, characterized in that an axial abutment (23) is provided for the hollow body (1), on which the hollow body (1) is supported in the direction of the axial die movement and which is stationary along the hollow body axis (3) during the axial die movement carried out by the forming die (9) relative to the hollow body (1).
4. The device according to any of the preceding claims, characterized in that

   • the forming drive (20, 20a) has a mandrel drive (21, 21a) and a drive controller (22, 22a) in addition to the die drive (19.19a),

   • by means of the mandrel drive (21, 21a), the mandrel (10, 10a) arranged in the interior of the hollow body (1) can be moved along the hollow body axis (3) through the die opening (11, 11a) with an axial mandrel movement counter to the axial die movement,

   • the hollow body wall (2) can be subjected to tension by means of the mandrel (10, 10a) in a direction of the axial mandrel movement due to the axial mandrel movement and can thereby be drawn through the die opening (11, 11a) relative to the forming die (9, 9a) in the direction of the axial mandrel movement, and

   • by means of the drive controller (22, 22a) for the forming drive (20, 20a), the mandrel drive (21, 21a) and the die drive (19, 19a) can be controlled in such a way that the axial mandrel movement and the axial die movement are superimposed on one another.
5. The device according to claim 4, characterized in that by means of the drive controller (22, 22a), the die drive (19, 19a) and the mandrel drive (21, 21a) can be controlled in such a way that the ratio of the speeds of the axial mandrel movement and the axial die movement is dependent on the ratio of the cross section of the hollow body (1) in the initial state and the cross section of the hollow body (1) after the forming process.
6. The device according to claim 4 or claim 5, characterized in that the ratio of the amounts of the axial mandrel movement and the axial die movement is reciprocal to the ratio of the speeds of the axial mandrel movement and the axial die movement.
7. The device according to one of claims 4 through 6, characterized in that

   • the forming die (9, 9a) can be moved by means of the die drive (19, 19a) with a positioning movement from a position away from the hollow body (1) to be formed to a position in which the forming die (9, 9a) is arranged on the outer side of the hollow body (1) and

   • by means of the drive controller (22, 22a), the die drive (19, 19a) and the mandrel drive (21, 21a) can be controlled in such a way that the mandrel drive (21, 21a) initiates the axial mandrel movement before the forming die (9, 9a) is arranged on the outer side of the hollow body (1) due to the positioning movement of the forming die (9, 9a).
8. An arrangement for forming a tubular hollow body (1) having a hollow body wall (2) made from a plastically deformable material and a hollow body axis (3) extending in the longitudinal direction of the hollow body (1),

   • the arrangement comprising a first forming device (7) and a second forming device (8), and the second forming device (8) being arranged downstream of the first forming device (7) in a forming process,

   • the first forming device (7) being designed to produce a preform (32) of a finished formed hollow body from the hollow body (1) in an initial state,

   • the preform (32) being designed as a tubular hollow body having a preform wall (38) made from a plastically deformable material and having a preform axis (37) coinciding with the hollow body axis (3), and

   • the second forming device (8) being designed to produce a subsequent shape of the preform (32), in particular to produce the finished formed hollow body, which has a subsequent forming wall,
   characterized in that
   as the first forming device (7), a forming device is provided

   • having a first forming die (26) designed to be arranged on the outer side of the hollow body (1) and provided with a first die opening (28) designed for receiving the hollow body (1),

   • having a first mandrel (27) designed to be arranged in the interior of the hollow body (1) and provided on its circumference with a first shape-imparting mandrel profile (29) having first mandrel profile projections (30) and first mandrel profile intermediate spaces (31) formed between the first mandrel profile projections (30), with the first mandrel profile projections (30) and the first mandrel profile intermediate spaces (31) extending along the hollow body axis (3) on the first mandrel (27) arranged in the interior of the hollow body (1), and the first mandrel profile intermediate spaces (31) opening towards the axially parallel inner side of the hollow body wall (2), and

   • having a first forming drive (34) with a first die drive (33), by means of which the first forming die (26) can be moved with an axial die movement along the hollow body axis (3) relative to the hollow body (1) and thereby along the first mandrel (27) arranged in the interior of the hollow body (1), wherein material of the hollow body wall (2) flows into the first mandrel profile intermediate spaces (31) of the first mandrel (27) due to the axial die movement of the first forming die (26) and an associated exceeding of the flow limit of the material of the hollow body wall (2), forming an inner profile (39) of the preform wall (38), and
   as the second forming device (8), a forming device is provided

   • having a second forming die (40) designed to be arranged on the outer side of the preform (32) and having a second die opening (42) designed for receiving the preform (32),

   • having a second mandrel (41) designed to be arranged in the interior of the preform (32) and provided on its circumference with a second shape-imparting mandrel profile (46) having second mandrel profile projections (47) and second mandrel profile intermediate spaces (48) formed between the second mandrel profile projections (47), with the second mandrel profile projections (47) and the second mandrel profile intermediate spaces (48) extending along the preform axis (37) on the second mandrel (41) arranged in the interior of the preform (32), and the second mandrel profile intermediate spaces (48) opening towards the axially parallel inner side of the preform wall (38) and receiving the inner profile (39) of the preform wall (38), and

   • having a second forming drive (50) with a second die drive (49), by means of which the second forming die (40) can be moved with an axial die movement along the preform axis (37) relative to the preform (32) and thereby along the second mandrel (41) arranged in the interior of the preform (32), wherein material of the preform (32) flows into the second mandrel profile intermediate spaces (48) of the second mandrel (41) due to the axial die movement of the second forming die (40) and an associated exceeding of the flow limit of the material of the preform wall (38), forming an inner profile (53) of the subsequent forming wall,
   the second forming die (40) being provided on the second die opening (42) with a shape-imparting die profile (43) having die profile projections (44) and die profile intermediate spaces (45) formed between the die profile projections (44), and, when the second forming die (40) is moved with the axial die movement,

   • the die profile projections (44) and the die profile intermediate spaces (45) of the second forming die (40) extending along the preform axis (37) and the die profile intermediate spaces (45) opening towards the axially parallel outer side of the preform wall (38) and

   • die profile projections (44) arranged on the axially parallel outer side of the preform wall (38) and second mandrel profile intermediate spaces (48) arranged on the axially parallel inner side of the preform wall (38) as well as die profile intermediate spaces (45) arranged on the axially parallel outer side of the preform wall (38) and second mandrel profile projections (47) arranged on the axially parallel inner side of the preform wall (38) in each case lying opposite to each other on the preform wall (38) in the radial direction of the preform axis (37), with the die profile projections (44) impinging material of the preform wall (38) in the direction of the second mandrel profile intermediate spaces (48) opposite the die profile projections (44) to form the inner profile (53) of the subsequent forming wall.
9. The arrangement according to claim 8, characterized in that the first shape-imparting mandrel profile (29) of the first mandrel (27) and the second shape-imparting mandrel profile (46) of the second mandrel (41) correspond to one another in their geometry.
10. The arrangement according to claim 9, characterized in that the first mandrel (27) is provided as the second mandrel (41).
11. The arrangement according to any of claims 8 to 10, characterized in that the first die opening (28) of the first forming die (26) has a smooth opening wall.
12. The arrangement according to any of claims 8 to 10, characterized in that the first forming die (26) is provided on the first die opening (28) with a first shape-imparting die profile having first die profile projections and first die profile intermediate spaces formed between the first die profile projections, when the first forming die (26) is moved with the axial die movement,

    • the first die profile projections and the first die profile intermediate spaces extending along the hollow body axis (3) and the first die profile intermediate spaces opening towards the axially parallel outer side of the hollow body wall (2) and

    • first die profile projections arranged on the axially parallel outer side of the hollow body wall (2) and first mandrel profile intermediate spaces arranged on the axially parallel inner side of the hollow body wall (2) as well as first die profile intermediate spaces arranged on the axially parallel outer side of the hollow body wall (2) and first mandrel profile projections arranged on the axially parallel inner side of the hollow body wall (2) in each case lying opposite to each other on the hollow body wall (2) in the radial direction of the hollow body axis (3), with the first die profile projections impinging material of the hollow body wall (2) in the direction of the first mandrel profile intermediate spaces opposite the first die profile projections to form the inner profile (39) of the preform wall (38) and
    the second forming die (40) has, as a shape-imparting die profile, a second shape-imparting die profile having second die profile projections and second die profile intermediate spaces formed between the second die profile projections.
13. The arrangement according to any of claims 8 through 12, characterized in that

    • the first die opening (28) of the first forming die (26) has an opening cross section that is smaller than a hollow body cross section (4) of the hollow body (1) in the initial state, the hollow body cross section (4) extending perpendicular to the hollow body axis (3), with the cross section (4) of the hollow body (1) being reduced due to the axial die movement of the first forming die (26) and an associated exceeding of the flow limit of the material of the hollow body wall (2) and/or

    • the second die opening (42) of the second forming die (40) has an opening cross section that is smaller than a preform cross section of the preform (32), the preform cross section extending perpendicular to the preform axis (37), with the cross section of the preform (32) being reduced due to the axial die movement of the second forming die (40) and an associated exceeding of the flow limit of the material of the preform wall (38).
14. A method for forming a tubular hollow body (1) having a hollow body wall (2) made from a plastically deformable material and a hollow body axis (3) extending in the longitudinal direction of the hollow body (1),

    • a forming die (9, 9a) being arranged on the outer side of the hollow body (1), with said forming die being provided with a die opening (11, 11a) designed to receive the hollow body (1),

    • a mandrel (10, 10a) being arranged in the interior of the hollow body (1) and provided on its circumference with a shape-imparting mandrel profile (15, 15a) having mandrel profile projections (16, 16a) and mandrel profile intermediate spaces (17, 17a) formed between the mandrel profile projections (16, 16a), with the mandrel profile projections (16, 16a) and the mandrel profile intermediate spaces (17, 17a) extending along the hollow body axis (3) on the mandrel (10, 10a) arranged in the interior of the hollow body (1), and the mandrel profile intermediate spaces (17, 17a) opening towards the axially parallel inner side of the hollow body wall (2), and

    • the forming die (9, 9a) being moved by means of a die drive (19, 19a) of a forming drive (20, 20a) with an axial die movement along the hollow body axis (3) relative to the hollow body (1) and thereby along the mandrel (10, 10a) arranged in the interior of the hollow body (1), wherein material of the hollow body wall (2) flows into the mandrel profile intermediate spaces (17, 17a) of the mandrel (10, 10a) due to the axial die movement and an associated exceeding of the flow limit of the material of the hollow body wall (2), forming an inner profile (18, 18a) of the hollow body wall (2),
    characterized in that
    a forming die (9, 9a) is moved relative to the hollow body (1) with the axial die movement by means of the die drive (19, 19a), which forming die is provided on the die opening (11, 11a) with a shape-imparting die profile (12, 12a) having die profile projections (13, 13a) and die profile intermediate spaces (14, 14a) formed between the die profile projections (13, 13a), when the forming die (9, 9a) is moved with the axial die movement

    • the die profile projections (13, 13a) and the die profile intermediate spaces (14, 14a) extending along the hollow body axis (3) and the die profile intermediate spaces (14, 14a) opening towards the axially parallel outer side of the hollow body wall (2) and

    • die profile projections (13, 13a) arranged on the axially parallel outer side of the hollow body wall (2) and mandrel profile intermediate spaces (17, 17a) arranged on the axially parallel inner side of the hollow body wall (2) as well as die profile intermediate spaces (14, 14a) arranged on the axially parallel outer side of the hollow body wall (2) and mandrel profile projections (16, 16a) arranged on the axially parallel inner side of the hollow body wall (2) in each case lying opposite to each other on the hollow body wall (2) in the radial direction of the hollow body axis (3), with the die profile projections (13, 13a) impinging material of the hollow body wall (2) in the direction of the mandrel profile intermediate spaces (17, 17a) opposite the die profile projections (13, 13a) to form the inner profile (18, 18a) of the hollow body wall (2).
15. The method according to claim 14, characterized in that a forming die (9) is arranged on the outer side of the hollow body (1) with a die opening (11), the opening cross section of which is smaller than a hollow body cross section (4) in an initial state, the hollow body cross section (4) extending perpendicular to the hollow body axis (3), and in that the cross section (4) of the hollow body (1) is reduced due to the axial die movement and the associated exceeding of the flow limit of the material of the hollow body wall (2).
16. A method for forming a tubular hollow body (1) having a hollow body wall (2) made from a plastically deformable material and a hollow body axis (3) extending in the longitudinal direction of the hollow body (1),

    • the method comprising a first method stage and a second method stage and the second method stage following the first method stage in the method,

    • a preform (32) of a finished formed hollow body being produced in the first method stage from the hollow body (1) in an initial state,

    • the preform (32) being designed as a tubular hollow body (1) having a preform wall (38) made from a plastically deformable material and having a preform axis (37) coinciding with the hollow body axis (3), and

    • in the second method stage, a subsequent shape of the preform (32), in particular the finished formed hollow body, is produced, which has a subsequent form wall,
    characterized in that
    in the first method stage

    • a first forming die (26) of a first forming device (7) is arranged on the outer side of the hollow body (1) in such a way that the first forming die (26) receives the hollow body (1) on a first die opening (28),

    • a first mandrel (27) of the first forming device (7) is arranged in the interior of the hollow body (1) and provided on its circumference with a first shape-imparting mandrel profile (29) having first mandrel profile projections (30) and first mandrel profile intermediate spaces (31) formed between the first mandrel profile projections (30), with the first mandrel profile projections (30) and the first mandrel profile intermediate spaces (31) extending along the hollow body axis (3) on the first mandrel (27) arranged in the interior of the hollow body (1), and the first mandrel profile intermediate spaces (31) opening towards the axially parallel inner side of the hollow body wall (2), and

    • the first forming die (26) is moved with an axial die movement along the hollow body axis (3) relative to the hollow body (1) and thereby along the first mandrel (27) arranged in the interior of the hollow body (1) by means of a first die drive (33) of a first forming drive (34) of the first forming device (7), wherein material of the hollow body wall (2) flows into the first mandrel profile intermediate spaces (31) of the first mandrel (27) due to the axial die movement of the first forming die (26) and an associated exceeding of the flow limit of the material of the hollow body wall (2), forming an inner profile (39) of the preform wall (38), and
    in the second method stage

    • a second forming die (40) of a second forming device (8) is arranged on the outer side of the preform (32) in such a way that the second forming die (40) receives the preform (32) on a second die opening (42),

    • a second mandrel (41) of the second forming device (8) is arranged in the interior of the preform (32) and provided on its circumference with a second shape-imparting mandrel profile (46) having second mandrel profile projections (47) and second mandrel profile intermediate spaces (48) formed between the second mandrel profile projections (47), with the second mandrel profile projections (47) and the second mandrel profile intermediate spaces (48) extending along the preform axis (37) on the second mandrel (41) arranged in the interior of the preform (32), and the second mandrel profile intermediate spaces (48) opening towards the axially parallel inner side of the preform wall (38) and receiving the inner profile of the preform wall (38), and

    • the second forming die (40) is moved with an axial die movement along the preform axis (37) relative to the perform (32) and thereby along the second mandrel (41) arranged in the interior of the preform (32) by means of a second die drive (49) of a second forming drive (50) of the second forming device (8), wherein material of the preform (32) flows into the second mandrel profile intermediate spaces (48) of the second mandrel (41) due to the axial die movement of the second forming die (40) and an associated exceeding of the flow limit of the material of the preform wall (38), forming an inner profile (53) of the subsequent form wall,
    a second forming die (40) being moved relative to the preform (32) with the axial die movement by means of the second die drive (49), which second forming die is provided on the second die opening (42) with a shape-imparting die profile (43) having die profile projections (44) and die profile intermediate spaces (45) formed between the die profile projections (44), when the second forming die (40) is moved with the axial die movement

    • the die profile projections (44) and the die profile intermediate spaces (45) of the second forming die (40) extending along the preform axis (37) and the die profile intermediate spaces (45) opening towards the axially parallel outer side of the preform wall (38) and

    • die profile projections (44) arranged on the axially parallel outer side of the preform wall (38) and second mandrel profile intermediate spaces (48) arranged on the axially parallel inner side of the preform wall (38) as well as die profile intermediate spaces (45) arranged on the axially parallel outer side of the preform wall (38) and second mandrel profile projections (47) arranged on the axially parallel inner side of the preform wall (38) in each case lying opposite to each other on the preform wall (38) in the radial direction of the preform axis (37), with the die profile projections (44) impinging material of the preform wall (38) in the direction of the second mandrel profile intermediate spaces (48) opposite the die profile projections (44) to form the inner profile (53) of the subsequent form wall.

Images