Patent Application
20250065384
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 extending in the longitudinal direction of the hollow body,
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 extending in the longitudinal direction of the hollow body,
Furthermore, the invention relates to methods that can be carried out with the aforementioned device and with the aforementioned arrangement, for forming a tubular hollow body that has a hollow body wall made of a plastically deformable material and a hollow body axis extending in the longitudinal direction of the hollow body.
For example, in the manufacturing of hollow shafts for motor vehicles, shaft blanks made of plastically deformable metallic materials are to be provided with external and/or internal toothings and in particular to be reduced in their diameter and/or their wall thickness over partial lengths. A common manufacturing method for producing toothings of shaft blanks is the axial forming by means of a forming tool that comprises a forming die enclosing the shaft blank on the outer side and a mandrel supporting the shaft blank in the interior thereof. Depending on the application, the forming die and/or the mandrel is provided with a shape-imparting toothing. A manufacturing method customary for reducing the diameter and/or wall thickness of shaft blanks is drawing.
Prior art of the generic type 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 outer side of the tube and a mandrel guided in the interior of the tube. At the same time as a wall thickness reduction, the tube wall is provided with an internal toothing. A mandrel with a gear-shaped cross-section is used to produce the internal toothing on the tube wall. In the tooth intermediate spaces on the mandrel, the teeth of the internal toothing are formed by the material of the tube wall plasticized due to 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 a high-quality internal toothing.
According to the invention, this object is achieved by the device according to Claim 1, the arrangement according to Claim 9 and the methods according to Claims 15 and 16.
In the case of the invention, for producing an internal toothing on a tubular hollow body made of a preferably metallic material and with a preferably circular cross-section, a forming tool is used which has a forming die with a profiled die opening and a mandrel with a profiled circumference. Essential to the invention is the fact that the forming die and the mandrel are rotated relative to one another about the axis of the hollow body to be formed, in such a way that die profile projections of the forming die arranged on one side of the hollow body wall and mandrel profile intermediate spaces arranged on the other side of the hollow body wall lie opposite to each other in the radial direction of the hollow body axis. Due to the mutual positioning of the die profile projections and the mandrel profile intermediate spaces according to the invention, during the forming process, the die profile projections bring about a complete filling of the mandrel profile intermediate spaces with plasticized material of the hollow body wall and, under certain circumstances, also a compaction of the wall material that has flowed into the mandrel profile intermediate spaces. As a result, the mandrel, whose profile reproduces 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 deviates at most minimally from the target geometry and is therefore of exceptionally 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 Claim 1 and according to the method according to Claim 15, the hollow body wall is provided with an inner profile with target geometry in one step.
By means of the arrangement according to Claim 9 and according to the method according to Claim 16, the creation of the inner profile with target geometry is distributed to a plurality of method stages.
In the first method stage, 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 subsequently optimized.
The optimization of the inner profile of the preform wall follows in at least one further method stage, in which the inner profile of a subsequent form of the preform, in particular the inner profile of the finished 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 method 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 hollow body wall is directly produced as a subsequent form from the preform.
In the case of the devices and methods according to the invention, the axial die movement can be performed as a continuous movement in the forming direction, but also as a movement with alternately performed long strokes in the forming direction and short return strokes in the opposite direction (“recursive axial forming”).
Particular embodiments of the devices and methods according to independent Claims 1, 9, 15 and 16 emerge from dependent Claims 2 to 8 and 10 to 14.
The measures of dependent Claims 2 to 8 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 method.
According to Claim 2, in a preferred embodiment of the invention, an internal toothing is created as an inner profile on the hollow body wall.
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 perpendicularly 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, the root line of which lies in the perpendicular projection onto the end face of the hollow body wall in the initial state outside the hollow body wall or coincides with the outer side of the hollow body wall. The tip line of the die profile lies in the perpendicular projection onto the end face of the hollow body wall in the initial state, in a region that can reach from the interior of the hollow body wall into 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 a shape-imparting toothing, is used to form a cylindrical hollow body, the root circle of the die toothing provided as the root line accordingly has a root circle diameter that is greater than or equal to the outer diameter of the hollow body to be formed in the initial state. The diameter of the tip circle of the die toothing is smaller than the outer diameter of the cylindrical hollow body in the initial state.
Corresponding is the situation on embodiments of the multi-stage arrangement according to the invention, in the case of which a preform with an unchanged cross-sectional size is manufactured from the hollow body in the initial state by means of the first forming device and/or a subsequent form with an unchanged cross-sectional size is manufactured from the preform by means of the second forming device.
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 such that the creation of the inner profile of the hollow body wall or of the preform wall and/or of the subsequent form wall is accompanied by a reduction of the hollow body cross-section or the preform cross-section (Claims 3, 14).
A cross-sectional reduction in the sense of the invention is to be understood as:
An embodiment of the device according to the invention or of the arrangement according to the invention is designed for a cross-sectional reduction of the hollow body by reducing the thickness of the hollow body wall, in the case of which the common cross-section of the mandrel and of the hollow body wall in the initial state is greater than the opening cross-section of the die opening or in the case of which the common cross-section of the first mandrel and of the hollow body wall in the initial state is greater 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 of the preform wall in the initial state is greater than the opening cross-section of the second die opening.
According to Claim 4, in a further embodiment of the invention, a stationary axial abutment is provided for the hollow body, on which abutment the hollow body is supported in the direction of the axial die movement when acted upon by the forming die.
The device according to Claim 5 and the forming method carried out with this device are intended 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 outer side of the hollow body is actively moved along the hollow body axis with the axial die movement. Due to the active movement of the forming die relative to the hollow body, the hollow body wall acted upon by the forming die is actively subjected to pressure by the forming die in the direction of the axial die movement. At the same time, the hollow body wall is subjected to tensile stress in the direction of the axial mandrel movement as a result of the axial mandrel movement directed in the opposite direction to the axial die movement.
By means of the drive controller of the forming drive according to the invention, the active axial mandrel movement and the active axial die movement of the forming die arranged on the outer side of the hollow body are superposed on one another. Due to the superposition of the two mentioned movements, the compressive stresses which build up in the hollow body wall due to the impact of the forming die over the wall cross-section are at least partially compensated by the tensile stresses in the hollow body wall resulting from the active axial mandrel movement.
Given corresponding, for example empirical, dimensioning and mutual coordination of the pressure load on the hollow body from the forming die and the tensile load on the hollow body from the mandrel, undesirable compression of the hollow body wall on the side, arranged in the direction of the axial die movement, of the forming die acting on the hollow body wall is at least largely prevented, even without additional reinforcement of the hollow body. At the same time, high forming speeds can be achieved as a result of the superposition of the active die movement and the active mandrel movement.
In general, both the axial mandrel movement and the axial die movement can be controlled both by position and force.
The forming speed of the device according to the invention and of the method according to the invention is largely independent of the material strength of the hollow body to be formed. In the case of high-strength materials, relatively high forming forces are required; at the same time, the tendency of hollow bodies made of high-strength materials to compress is however relatively low. Conversely, tubular hollow bodies made of materials of low strength have a relatively high tendency to compress, but a cross-sectional reduction of such hollow bodies is already possible with relatively low forming forces.
According to Claim 6, in the case of the invention, the ratio of the speeds of the axial mandrel movement and of the axial die movement of the forming die arranged on the outer side of the hollow body is set by means of the drive controller of the forming drive as a function of 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 after the forming process. In particular in the case of a cross-sectional reduction, the value of the speed of the axial die movement of the forming die arranged on the outer side of the hollow body can be greater, but also smaller, than the value of the speed of the axial mandrel movement. In the context of an experimental use of the invention, it was possible to achieve high-quality processing results 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 7, in a further embodiment of the invention, it is provided that the ratio of the values of the axial mandrel movement and of the axial die movement during the forming process is reciprocal to the ratio of the speeds of the axial mandrel movement and of the axial die movement during the forming process. It is thereby ensured 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.
In a further advantageous embodiment of the invention, Claim 8 provides 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 to a position in which the forming die is arranged on the outer side of the hollow body, and that the die drive and the mandrel drive are controlled by means of the drive controller of the device drive 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. Upon the first contact of the forming die with the hollow body to be formed, the mandrel and the hollow body which is driven along the hollow body axis and subjected to tensile stress during the forming process is thus already in movement. Preferably, the positioning movement of the forming die is carried out in the direction of the axial die movement.
In order to carry out the multi-stage forming method, forming devices can be used whose mandrels have mandrel profile intermediate spaces with differently sized intermediate space cross-sections. Preferably, by means of the second mandrel, the inner profile with the target geometry is created from the inner profile of the preform. In doing so, wall material is fed by the second forming die to the profile projections of the inner profile of the preform produced in the mandrel profile intermediate spaces of the first forming die. Accordingly, the first mandrel profile intermediate spaces of the first mandrel have to receive less wall material than the second mandrel profile intermediate spaces of the second mandrel. If, at the same time, the cross-section of the first mandrel profile intermediate spaces is greater than the cross-section of the second mandrel profile intermediate spaces, the first mandrel profile intermediate spaces have an oversize compared to the inner profile of the preform produced on the first mandrel profile, due to which oversize the first mandrel and the preform can be separated from one another with relatively little force after completion of the first method stage.
In a preferred embodiment of the invention, the first shape-imparting mandrel profile of the first mandrel and the second shape-imparting mandrel profile of the second mandrel correspond to one another in their geometry (Claim 10). In this way, it can be particularly ensured 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. On the second forming device, by means of the second forming die and the second mandrel interacting therewith, the geometry of the inner profile produced by means of the first mandrel is brought into conformity with the target geometry specified by the identical mandrel profile, or at least brought closer to the target geometry.
Particularly high-quality processing results can be achieved if the same mandrel is used in the second method stage as in the first method stage (Claim 11). In this case, the mandrel can remain in the interior of the then present preform after the first method stage has been completed. Therefore, the processing of the preform by the second forming device does not have to be preceded by a mandrel change on the preform, which may impair the processing quality.
According to Claim 12, 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. Accordingly, the optimized filling of the mandrel profile intermediate spaces with plasticized material of the hollow body wall according to the invention takes place exclusively in the second method step of the forming method according to the invention.
In deviation from this, in the case of the embodiment of the invention according to Claim 13, precautions for an optimized filling of the mandrel profile intermediate spaces with plasticized material of the hollow body wall have already been taken on the first forming device of the multi-stage arrangement.
In the following, the invention is explained in more detail on the basis of schematic illustrations given by way of example. Shown are:
According to
A steering shaft for a motor vehicle is to be manufactured from the tube 1.
For this purpose, single-stage devices 5, 5a shown in
The devices 5, 5a and the forming devices 7, 8 with the respective formed workpieces are shown in
The device 5 shown in
A forming die 9 of the device 5 designed to be arranged on the outer side of the tube 1 is installed in a tool holder of the axial forming machine that can move along the tube axis 3. A mandrel holder of the axial forming machine, also movable 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 not shown in
The forming die 9 has a die opening 11 (“calibration section”) designed for receiving the tube 1. At the die opening 11, the forming die 9 is provided with a shape-imparting die profile in the form of a shape-imparting die toothing 12. The die toothing 12 has die teeth 13 as die profile projections and die tooth intermediate spaces 14 formed between the die teeth 13 as die profile intermediate spaces. The root circle diameter of the die opening 11 is smaller than the diameter of the tube cross-section 4 in the initial state with the tube 1 still undeformed.
The mandrel 10 is designed to be arranged in the interior of the tube 1 and is provided on its circumference with a shape-imparting mandrel profile designed as a shape-imparting mandrel toothing 15. The shape-imparting mandrel toothing 15 is formed by mandrel profile projections in the form of mandrel teeth 16 and by mandrel tooth intermediate spaces 17 arranged between the mandrel teeth 16 as mandrel profile intermediate spaces.
The die teeth 13 and the die tooth intermediate spaces 14 extend along the tube axis 3 on the forming die 9, which is seated on the outer side of the tube 1. The die tooth intermediate spaces 14 open towards the axially parallel outer side of the tube wall 2.
On the mandrel 10 in the interior of the tube 1, the mandrel teeth 16 and the mandrel tooth intermediate spaces 17 also extend along the tube axis 3. The mandrel tooth intermediate spaces 17 open towards the axially parallel inner side of the tube wall 2.
The forming die 9 and the mandrel 10 are positioned relative to one another around the tube axis 3 in such a way that the die teeth 13 arranged on the axially parallel outer side of the tube wall 2 and the mandrel tooth intermediate spaces 17 arranged on the axially parallel inner side of the tube wall 2 as well as the die tooth intermediate spaces 14 arranged on the axially parallel outer side of the tube wall 2 and the mandrel teeth 16 arranged on the axially parallel inner side of the tube wall 2 in each case lie opposite to 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 inner side thereof with an inner profile in the form of an internal toothing 18.
A die drive 19 of a forming drive 20 of the device 5 is used to produce an axial die movement of the forming die 9 required for this purpose. In addition to the die drive 19, the forming drive 20 comprises a mandrel drive 21 and a drive controller 22.
At the start 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 tube axis 3 until the forming die 9 reaches from a position away from the tube 1 the right-hand end of the tube 1 in
In addition, the mandrel drive 21 moves the mandrel holder of the axial forming machine with the mandrel 10 along the tube axis 3 from a position to the left of the tube 1 in
The tube 1 to be formed is mounted on the axial forming machine with its left-hand end in
In order to form the tube 1, the forming die 9 is now moved by means of the die drive 19 from its initial position at the right-hand end of the tube 1 with an axial die movement relative to the tube 1, which is supported on the stationary axial abutment 23 and is therefore also stationary, in the direction of the stationary axial abutment 23. 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 in the interior of the tube 1. The direction of movement of the forming die 9 during the axial die movement is illustrated by an arrow 24 in
Due to the oversize of the undeformed 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 flow limit of the material of the tube wall 2 to be exceeded on the side of the forming die 9 located in the direction of arrow 24. The tube cross-section 4 is reduced due to the axial die movement and material from the tube wall 2 flows into the mandrel tooth intermediate spaces 17 of the mandrel 10, forming the internal toothing 18 of the tube wall 2 and simultaneously elongating the tube wall 2.
The die teeth 13 of the die toothing 12, due to their arrangement opposite the mandrel tooth intermediate spaces 17 of the mandrel 10, ensure that the mandrel tooth intermediate spaces 17 are completely filled with the flowing material of the tube wall 2, and that the internal toothing 18 of the tube wall 2 is therefore produced precisely with its target geometry specified by the mandrel toothing 15.
In the case of the tube 1, if there is a risk of the tube 1 being compressed during the forming process, for example due to the tube length, the above kinematics of the forming process are modified.
In deviation from the sequences described above, in order to avoid a compression of the tube 1, an axial mandrel movement of the mandrel 10 directed in the opposite direction to the axial die movement and carried out in the direction of an arrow 25 in
The speeds of the axial die movement and of the axial mandrel movement can be different in this case. For example, by means of the drive controller 22, the speed of the axial die movement of the forming die 9 in the direction of arrow 24 can be set to 60 mm/s and the speed of the axial mandrel movement of the mandrel 10 in the direction of arrow 25 can be set to 15 mm/s.
When the free end of the tube 1 enters the die opening 11 at the start of the forming process, the tube wall 2 is pressed against the mandrel 10 in the relevant region. A force fit is thereby produced between the tube wall 2 and the mandrel 10.
At the same time, the axial movement of the forming die 9 causes the tube wall 2 to be subjected to pressure on its side located in the direction of arrow 24, and the flow limit of the material of the tube 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 when an axial die movement and an axial mandrel movement are superposed while the tube 1 is being acted upon by the forming die 9.
As a result of the force fit between the tube wall 2 and the mandrel 10, the tube wall 2, which is acted upon on the outer side by the forming die 9, is subjected to tensile stress in the direction of arrow 25 by means of the mandrel 10. The mandrel 10 driven by means of the mandrel drive 21 therefore actively pulls the tube wall 2 in the direction of arrow 25 through the die opening 11, and the thickness of the tube wall 2 is reduced while simultaneously elongating the tube 1 and simultaneously producing the internal toothing 18 on the tube 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 corresponding control of the die drive 19 and the mandrel drive 21 by means of the drive controller 22, the forming of the tube wall 2 takes place without the tube 1 being compressed on the side of the forming die 9 located in the direction of arrow 24. As a result, in order to prevent compression of the tube 1, in the case of the device 5 there is also no need for additional reinforcement on the outer side of the tube 1.
Corresponding control of the die drive 19 and the mandrel drive 21 ensures that the die drive 19 and the mandrel drive 21 can be stopped simultaneously when the desired forming length is reached on the tube 1.
Due to the fact that an axial die movement and an axial mandrel movement directed in the opposite direction thereto are carried out at the same time, a high forming speed can be achieved. Regardless of the high forming speed, a high-quality processing result is obtained on the tube 1.
While the devices 5, 5a shown in
The first forming device 7 of the arrangement 6 (
The first forming die 26 of the first forming device 7 is provided with a first die opening 28 for receiving the tube 1. In the example shown, the first die opening 28 is smooth-walled. The diameter of the first die opening 28 corresponds to the root circle diameter of the toothed die opening 11 on the forming die 9 shown in
On its circumference, the first mandrel 27 of the first forming device 7 has a first shape-imparting mandrel toothing 29 as the first shape-imparting mandrel profile with first mandrel profile projections in the form of first mandrel teeth 30 and first mandrel tooth intermediate spaces 31 formed between the first mandrel teeth 30 as the first mandrel profile intermediate spaces. On the first mandrel 27 arranged in the interior of the tube 1, the first mandrel teeth 30 and the first mandrel tooth intermediate spaces 31 extend along the tube axis 3. The first mandrel tooth intermediate spaces 31 open towards the axially parallel inner side of the tube wall 2. The toothing geometry of the toothed first mandrel 27 of the first forming device 7 forms the target geometry of the toothed inner side of the tube wall 2 on the finished formed tube.
In a first method 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 method stage of the two-stage forming process in principle correspond to the sequences of the single-stage forming method in
A first die drive 33 of a first forming drive 34 of the first forming device 7 produces an axial die movement of the first forming die 26, which is seated on the tube 1, relative to the tube 1 along the tube axis 3 and along the first mandrel 27 arranged in the interior of the tube 1.
If there is a risk of compression, an axial mandrel movement of the first mandrel 27 carried out by means of a first mandrel drive 35 of the forming drive 34 and directed in the opposite direction to the axial die movement of the first forming die 26 is superposed on 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 method 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 inner profile in the form of an internal toothing 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 stage shown in
According to
A second die opening 42 of the second forming die 40 is designed for receiving the preform 32 and has a shape-imparting die toothing 43 as a shape-imparting die profile on the opening wall. The shape-imparting die toothing 43 is formed by die profile projections in the form of die teeth 44 and die tooth intermediate spaces 45 formed between the die teeth 44 as die profile intermediate spaces.
With the second forming die 40 arranged on the outer side of the preform 32, the die teeth 44 and the die tooth intermediate spaces 45 extend along the preform axis 37. The die tooth intermediate spaces 45 open towards the axially parallel outer side of the preform wall 38. The root circle diameter of the die toothing 43 at the second die opening 42 of the second forming die 40 corresponds to the diameter of the smooth-walled first die opening 28 at the first forming die 26 of the first forming device 7.
The second mandrel 41 of the second forming device 8 has the same design as the first mandrel 27 of the first forming device 7.
On its circumference, the second mandrel 41 has a second shape-imparting mandrel toothing 46 as a second shape-imparting tooth profile with second mandrel profile projections in the form of second mandrel teeth 47 and with second mandrel profile intermediate spaces in the form of second mandrel tooth intermediate spaces 48. Also the second shape-imparting mandrel toothing 46 reproduces the internal toothing to be created on the finished formed tube with its target geometry.
On the second mandrel 41 arranged in the interior of the preform 32, the second mandrel teeth 47 and the second mandrel tooth intermediate spaces 48 extend along the preform axis 37. The second mandrel tooth intermediate spaces 48 open towards the axially parallel inner side of the preform wall 38.
The second forming die 40 and the second mandrel 41 are arranged relative to one another around the preform axis 37 in such a way that the die teeth 44 arranged on the axially parallel outer side of the preform wall 38 and the second mandrel tooth intermediate spaces 48 arranged on the axially parallel inner side of the preform wall 38 as well as the die tooth intermediate spaces 45 arranged on the axially parallel outer side of the preform wall 38 and the second mandrel teeth 47 arranged on the axially parallel inner side of the preform wall 38 in each case lie opposite to each other on the preform wall 38 in the radial direction of the preform axis 37. At the start of the second method stage of the forming process, the mandrel tooth intermediate spaces 48 receive the inner profile 39 of the preform 32 produced in the first method stage.
The sequences of the second method stage of the two-stage forming process also correspond in principle to the sequences of the single-stage forming process carried out by means of the device 5 and shown in
A second die drive 49 of a second forming drive 50 moves the second forming die 40, which is seated on the preform 32, with an axial die movement relative to the preform 32 along the preform axis 37 and along the second mandrel 41 arranged in the interior of the preform 32.
If there is a risk of compression, an axial mandrel movement of the second mandrel 41 directed in the opposite direction and produced by a second mandrel drive 51 is superposed on the axial die movement of the second forming die 40. In doing so, 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 method stage, the die teeth 44 of the die toothing 43 on the second forming die 40, due to their arrangement opposite the second mandrel tooth intermediate spaces 48 of the second mandrel 41, ensure that the second mandrel tooth intermediate spaces 48 are completely filled with the flowing material of the preform wall 38 and that, on the finished formed tube, an internal toothing 53 is therefore produced as an inner profile, the geometry of which corresponds precisely to its target geometry specified by the second mandrel toothing 46.
Just like the device 5 shown in
A forming die 9a of the device 5a has a die opening 11a (“calibration section”) designed for receiving the tube 1. At the die opening 11a, the forming die 9a is provided with a shape-imparting die profile in the form of a shape-imparting die toothing 12a. The die toothing 12a has die teeth 13a as die profile projections and die tooth intermediate spaces 14a formed between the die teeth 13a as die profile intermediate spaces.
In deviation from the forming die 9 shown in
A mandrel 10a is designed to be arranged in the interior of the tube 1 and is provided on its circumference with a shape-imparting mandrel profile designed as a shape-imparting mandrel toothing 15a. The shape-imparting mandrel toothing 15a is formed by mandrel profile projections in the form of mandrel teeth 16a and by mandrel tooth intermediate spaces 17a arranged 16a as mandrel profile intermediate spaces between the mandrel teeth.
The die teeth 13a and the die tooth intermediate spaces 14a extend along the tube axis 3 on the forming die 9a, which is seated on the outer side of the tube 1. The die tooth intermediate spaces 14a open towards the axially parallel outer side of the tube wall 2.
On the mandrel 10a in the interior of the tube 1, the mandrel teeth 16a and the mandrel tooth intermediate spaces 17a also extend along the tube axis 3. The mandrel tooth intermediate spaces 17a open towards the axially parallel inner side of the tube wall 2.
The forming die 9a and the mandrel 10a are positioned relative to one another around the tube axis 3 in such a way that the die teeth 13a arranged on the axially parallel outer side of the tube wall 2 and the mandrel tooth intermediate spaces 17a arranged on the axially parallel inner side of the tube wall 2 as well as the die tooth intermediate spaces 14a arranged on the axially parallel outer side of the tube wall 2 and the mandrel teeth 16a arranged on the axially parallel inner side of the tube wall 2 in each case lie opposite to each other on the tube wall 2 in the radial direction of the tube axis 3.
Due to the dimensioning of the tip and root circle diameters on the die toothing 12a, the device 5a produces an inner profile in the form of an internal toothing 18a on the inner side of the tube wall 2, without reducing the wall thickness of the tube wall 2.
The sequences in forming the tube 1 by means of the device 5a also correspond to the sequences on the device 5 shown in
A die drive 19a of a forming drive 20a of the device 5a is used to produce an axial die movement of the forming die 9a. In addition to the die drive 19a, the forming drive 20a comprises a mandrel drive 21a and a drive controller 22a.
In order to form the tube 1, the forming die 9a is moved by means of the die drive 19a from its initial position at the right-hand end of the tube 1 with an axial die movement relative to the tube 1, which is supported on the stationary axial abutment 23 and is therefore also stationary, in the direction of the stationary axial abutment 23. During the axial die movement, the forming die 9a moves in the direction of arrow 24 along the tube axis 3 relative to the tube 1 and also along the mandrel 10a arranged in the interior of 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 intermediate spaces 17a of the mandrel 10a, forming the internal toothing 18a of the tube wall 2.
Also the die teeth 13a of the die toothing 12a ensure, due to their arrangement opposite the mandrel tooth intermediate spaces 17a of the mandrel 10a, that the mandrel tooth intermediate spaces 17a are completely filled with the flowing material of the tube wall 2 and the internal toothing 18a of the tube wall 2 is therefore produced precisely with its target geometry specified by the mandrel toothing 15a.
| Number | Date | Country | Kind |
|---|---|---|---|
| 21198852.2 | Sep 2021 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/076221 | 9/21/2022 | WO |
