CN117772853A

CN117772853A - Method for manufacturing a drive shaft, bend straightener and drive shaft

Info

Publication number: CN117772853A
Application number: CN202311242957.2A
Authority: CN
Inventors: D·卡茨施
Original assignee: Volkswagen Automotive Co ltd
Current assignee: Volkswagen Automotive Co ltd
Priority date: 2022-09-27
Filing date: 2023-09-25
Publication date: 2024-03-29
Also published as: DE102022210175A1

Abstract

In a method for producing a drive shaft (1), the drive shaft (1) has at least two sections (10, 11a,11 b) welded to one another in a material-bonded manner, wherein at least one of the sections is designed as a hollow shaft, and deep rolling is performed in the region of the welded joints (14 a,14 b) of the sections welded to one another. The deep rolling is carried out in a bend leveler (20, 20 '), wherein the straightness measurement of the drive shaft (1) for the bend leveling of the drive shaft and the deep rolling are carried out in the same clamping device in the bend leveler (20, 20'). Furthermore, a bend straightener and a drive shaft suitable for carrying out the method are presented.

Description

Method for manufacturing a drive shaft, bend straightener and drive shaft

Technical Field

The invention relates to a method for producing a drive shaft (or drive shaft) having at least two welded-together sections, at least one of which is designed as a hollow shaft, wherein deep rolling is carried out in the region of the welded connection of the welded-together sections.

The invention further relates to a bend straightener comprising at least one support on which a shaft is supported laterally and rotatably about its longitudinal axis, a drive for rotating the shaft about its longitudinal axis, means for measuring the straightness of the shaft, and means for straightening the shaft when the shaft is supported on the at least one support.

The invention further relates to a drive shaft for a motor vehicle, which drive shaft has at least two sections welded to one another in a material-bonded or material-sealed manner.

Background

In automotive manufacture, the drive shafts for torque transmission are initially manufactured as solid shafts. The coupling structure, for example for connecting constant velocity joints or the like, is constructed directly on the solid shaft. In order to reduce the weight of the components, it is known to design the drive shaft as a hollow shaft, as described in DE 21 35 909A. In DE 21 35 909A, such a hollow shaft is made of a single tube. This can be achieved, for example, by rotary forging. However, the flexibility of the shaping is limited in this case.

Furthermore, the known drive shafts are assembled from several initially separate parts. By using a welding process, the hollow part can be designed more load-wise to achieve further weight savings. However, such joints typically result in a loss of strength that may be amplified in the case of unbalanced material pairings.

DE 10 201 2 011 442A1 describes a multi-part propeller shaft for connecting two constant velocity joints. The drive shaft comprises a central section designed as a tube with a constant inner diameter over its entire length and having two axial ends, and two corrugated journals as end sections, which journals are welded to each axial end of the central member.

Another drive shaft of this type is disclosed in DE 10 201 3 006 792A1. In this case, at least one groove-shaped recess is introduced into the shaft in the region of the welded joint by rolling with a rolling tool over the circumference of the shaft. The inherent internal stresses thus created increase their dynamic strength. By introducing a circumferential groove into the outer surface of the shaft in the region of the heat affected zone of the previous welding process, the strength is purposefully adjusted. In particular, the inherent internal stresses in the material of the shaft should be increased by rolling, so that the strength is specifically set. By introducing intrinsic internal stresses in the heat affected zone or near-surface edge layer region including the heat affected zone, the tensile stresses that can be tolerated should be increased, thereby increasing the dynamic strength. The recess is arranged as a stamped structure next to the actual weld seam, and the introduction of such a recess can take place directly after the welded connection.

DE 10 200 9 012 973A1 also discloses a material-bonded connection between two cylindrical elements, in particular tubular elements, made of metal, which is achieved by press welding or friction welding and forms at least one external bead. The bead may be applied to one of the cylindrical elements, for example by rolling, to cover the connection point and act as a sacrificial material in terms of corrosion. A thickening structure is maintained at the junction.

DE 10 201 3 008 658A1 describes another drive shaft in which bevel gears are connected to a hollow shaft by friction welding. The resulting weld is flattened by deep rolling. Deep rolling results in the introduction of internal stresses in the weld to avoid crack propagation and localized welding of the parts involved. Deep rolling also increases the strength of the weld. For example, by deep rolling, it is possible to close a gap that may exist after friction welding, for example, to avoid parts being welded only partially.

However, it is difficult to incorporate deep rolling during manufacture. Typically, deep rolling is performed by dedicated equipment. The drive shaft is transported to the apparatus where it is processed and from there must be transported to subsequent production steps. Therefore, the process flow for manufacturing the propeller shaft is complicated.

In the case of a joint shaft, a pressure straightening tool is known from DE 2 556 971A, which straightens by pressing. The fluctuations in width and diameter can also be compensated for with pressing. However, these processes are inevitably interrelated.

Bend straightening devices suitable for drive shafts are known, for example, from DD 294 111a5, DE 10 201 8 006 987A1 and DE 10 201 9 114 112A1.

Disclosure of Invention

Against this background, the object of the present invention is to provide a method for producing a drive shaft, in which deep rolling (Festwalzen) for increasing the service life is more effectively integrated into an existing process chain for producing lightweight, torsionally loaded hollow components.

The technical problem is solved by a method of manufacturing a propeller shaft. The drive shaft has at least two sections welded to one another in a material-bonded manner, at least one of the sections being designed as a hollow shaft, wherein deep rolling is carried out in the region of the welded joints of the sections welded to one another, characterized in that deep rolling is carried out in a bend straightening machine, wherein the straightness measurement for the bend straightening of the drive shaft and the deep rolling are carried out in the same clamping device in the bend straightening machine.

By integrating deep rolling into the bend straightening process, the process time required for deep rolling is kept to a minimum. In particular, there is no need to transfer the drive shaft to a dedicated deep rolling device. Instead, deep rolling and bend straightening can be performed in the same clamping device of the drive shaft. It should be emphasized that, unlike straightening rolling, in the solution according to the invention, the two processes, deep rolling and bending straightening, remain independent of each other and do not interact. In this respect, the solution of the invention allows greater flexibility in terms of component optimisation.

In particular, the rotation of the drive shaft for straightness measurement (for detecting dimensional deviations) can be used for deep rolling of the welded joint in the bend leveler, so that the additional time consumption for deep rolling is kept short.

In a special embodiment variant, for particularly efficient production, the straightness measurement is already started in the course of deep rolling over time.

Preferably, after deep rolling and after measuring the straightness, the bend straightening is performed in a clamping device for deep rolling in a bend straightener. Thus, the process can be very time efficient in connecting deep rolls.

According to another particular embodiment, the drive shaft may be hardened prior to deep rolling. The possible hardness distortions are compensated for by bend straightening.

Furthermore, alternatively or additionally, the drive shaft may be tempered after deep rolling in order to adjust its strength parameters in a desired manner. Tempering may be limited to a partial section of the drive shaft, or may be performed with different setting parameters, where appropriate.

According to another particular embodiment, the bead (or electrode) of the welded joint may be removed in a cutting manner prior to deep rolling. This allows a particularly uniform surface topography to be obtained in the region of the weld, which is enhanced by subsequent deep rolling.

According to a further special embodiment, the drive shaft in the bend straightening machine is rotatably supported on a lateral support for bend straightening, wherein the rolls or balls for deep rolling are arranged opposite the support and are pressed laterally against the drive shaft in the direction of the support during deep rolling. This achieves a particularly short process time, since the drive shaft can be clamped very quickly in the bend leveler. For example, rotation of the drive shaft may be achieved by clamping the spindle between two opposing spindles.

However, it is also possible to provide a deep rolling tool for deep rolling, which tool is supported rotatably on the bend-straightening machine and which tool surrounds the drive shaft annularly. In this case, the rotation of the drive shaft may be achieved, for example, by clamping one end thereof to a rotatable jaw chuck or the like.

According to another particular embodiment, the drive shaft may have a central section in the form of a hollow shaft, and end sections connected to the ends of the central section, the end sections each having a coupling structure for torque transmission. The relevant weld points between the end sections and the central section can be deep rolled synchronously in the bend leveler, which in turn has a positive effect on the manufacturing time.

In addition, the invention also provides a bending straightener suitable for executing the method. The bend straightener comprises at least one support on which the shaft is supported laterally and rotatably about its longitudinal axis; a drive for rotating the shaft about its longitudinal axis; means for straightness measurement of the shaft; means for straightening the shaft when the shaft is supported on the at least one support; a roller or a roller arranged opposite the support, and a pressure device for pressing the roller or the roller against the support, so that the roller or the roller can be laterally abutted against the shaft for deep rolling. By means of such a bend straightener, for example, it is possible to manufacture, for example, a drive shaft very quickly and efficiently, since there is no need to re-fasten the shaft in order to deep roll a partial section of the shaft. In addition to saving operating costs, the footprint requirements of the applicable production facility are reduced.

In particular, a drive shaft for a motor vehicle can be produced, which has at least two sections welded to one another in a material-bonded manner, at least one of the sections being designed as a hollow shaft, wherein the drive shaft is tempered at a welded joint between the two sections welded to one another in a material-bonded manner, has a machined surface and has a deep-rolled surface structure, which has a built-up internal stress in the radially outer edge region.

Drawings

The method of carrying out the invention is described in more detail below by means of an embodiment shown in the drawings. In the drawings:

figure 1 shows a flow chart for illustrating an embodiment of a method of manufacturing a propeller shaft,

FIG. 2 shows a schematic view of a bend leveler with means for bend leveling and deep rolling, and

FIG. 3 shows a schematic view of another bend leveler with a device for bend leveling and deep rolling.

Detailed Description

The embodiment described in more detail below first of all relates to the production of a drive shaft 1, which drive shaft 1 has at least two material-bonded, in particular welded, sections 10, 11a,11b.

For illustration purposes, the drive shaft 1 of the embodiment has a central section 10 in the form of a hollow shaft and end sections 11a and 11b connected to its ends.

The end sections 11a and 11b may be connected to the central section 10 of the drive shaft 1, for example by welding. In fig. 2 and 3, the corresponding weld joints are marked with reference numerals 14a and 14 b. As a joining process, friction welding is preferably used to produce a material-bonded joint of the sections 10, 11a,11b without a bulky heat affected zone.

Furthermore, the end sections 11a and 11b may consist of a different material than the central section 10 of the drive shaft 1. In particular, different alloy steels may be used for the individual sections 10, 11a and 11b of the drive shaft 1.

The welded sections 10, 11a,11b can smoothly transition into one another at welded joints 14a and 14b having the same outer cross section.

The end sections 11a and 11b each have a coupling structure 12a and 12b for torque transmission. These coupling structures 12a and 12b can be designed, for example, as spline shafts, notched teeth or the like. They can be produced on the respective end section 11a,11b in a modified and/or cut-off manner.

The end sections 11a and 11b can themselves be configured as hollow shafts. But may also be made of a solid material. Furthermore, a solid material structure may be provided at least in the region of the connecting structures 12a and 12b, which optionally transitions into the hollow shaft sections 13a, 13b for connection to the central section 10.

The propeller shaft 1, which is shown in more detail by way of example in fig. 2 and 3 in particular, can be formed in particular as a profile shaft for connecting two constant velocity joints or the like. For this purpose, the coupling structures 12a and 12b can be engaged in torque transmission with a suitable coupling structure on the corresponding inner part of the constant velocity joint.

However, it must be emphasized that the drive shaft 1 shown in the figures is only exemplary and can be designed in different ways. In particular, the number of mutually welded elements of the drive shaft 1 may be smaller or larger than the number shown in the figures. In addition, other components of the drive train may be connected by the coupling structures 12a and 12b in addition to the constant velocity universal joint described above.

Due to the welded joints 14a,14b between the individual sections 10, 11a,11b of the drive shaft 1, their strength will be somewhat impaired. This weakening is counteracted by a local deep rolling in the area a around the welded joint 14a,14 b. By deep rolling, the radially outer edge region of the propeller shaft 1 in the region a around the weld joints 14a,14b is subjected to internal stress by plastic deformation, which improves strength.

Preferably, the area a covers an axial length of about 5 to 50 mm. In particular, the actual welded joints 14a,14b may also be subjected to a seaming process (uberwalzen). The internal stresses formed by deep rolling can be adjusted in such a way that they are not completely released by the subsequent process steps, but remain at the desired level on the finished drive shaft 1.

An embodiment of a method for manufacturing such a propeller shaft 1 will now be explained in more detail using fig. 1.

The aim here is to further reduce the weight of the torsionally loaded hollow part, preferably by optionally using a hybrid material combination of different alloy steels.

In fig. 1, the sections of the drive shaft 1 (see a in fig. 1) are first produced separately, which are then connected to one another by welding. In the embodiment shown, these are end sections 11a and 11b, only one of which is shown by way of example in fig. 1, and a central section 10 in the form of a hollow shaft. In principle, the manufacturing process that can be used for this purpose can be chosen arbitrarily.

For example, in this example, the end sections 11a and 11b are turned into journals and then provided with teeth for the coupling structures 12a and 12b.

For example, the central section 10 may be cut out of a tube to a desired length.

However, these sections 10, 11a,11b may also be manufactured in other ways (e.g. retrofit technology).

The desired sections 10, 11a,11b of the drive shaft 1 are then assembled and welded together as described above, for example, but not limited to, by friction welding (see b in fig. 1).

In a further step (see c in fig. 1), the final outer contour thereof can be manufactured, for example, by machining the drive shaft 1. In this case, possible beads 15 can be removed, as shown in fig. 1, by turning away said beads 15. If the beads 15 remain, this is disadvantageous for the processing steps and the component properties described below.

The properties of hardness, strength and ductility may preferably be locally adjusted as required by a targeted heat treatment (see d in fig. 1) after the above-mentioned cutting machining. Thus, a hardened and grain-like material is formed in the region of the weld joints 14a and 14 b.

Warpage, i.e. dimensional deviations from the desired target shape, may occur upon hardening, caused for example by internal stresses generated by the structure transformation process.

In order to eliminate dimensional deviations due to hardening or other previous manufacturing steps, the drive shaft 1 is straightened (see f in fig. 1).

As a process, bend straightening is applied for this purpose in a corresponding bend straightener. In bend straightening, the dimensional deviation is initially measured by rotation of the drive shaft 1 about its longitudinal axis B by means of a suitable measuring device. According to the respective dimensional deviations, the drive shaft 1 is permanently deformed by the application of transverse forces in such a way that these dimensional deviations are reduced. An example in which a corresponding bend leveler is mentioned at the beginning can be used in this case.

The force required for bend straightening depends on the workpiece diameter, the wall thickness, the material, in particular its material state, and the curvature of the component. In this case, forces between 20kN and 20000kN can be generated, causing plastic deformation of the component.

According to the invention, in the process step of bend straightening (see f in fig. 1), the rotation of the drive shaft 1 is additionally used for deep rolling (see e in fig. 1) of the welded joints 14a,14 a. For this purpose, the drive shaft 1 does not have to be clamped again.

Deep rolling is a modified method for surface and edge area processing according to DIN 8580 (German industry Standard 8580). In this case, the components concerned are processed with cylindrical or spherical rolling bodies, also referred to below as rolls or balls, which consist of hard metals or ceramics. The change in the edge area is produced by leveling of rough spots, introduction of internal stresses and cold work hardening. The machining load acting on the edge region during machining can be applied mechanically or hydrostatically. In the case of mechanical load introduction, the load is usually introduced by means of a spring mechanism, so that the rolling force F _w Depending on the travel of the rolled body. However, dimensional deviations in the form of out-of-roundness (or ovality) lead to variations in rolling force and thus to localized areasDifferent edge zone characteristics. In contrast, in hydrostatic deep rolling, the introduction of the load is introduced by a hydrostatic tracking system, which causes the rolling force F _w Regardless of travel. This results in a more uniform influence on the edge area.

During rolling, elasto-plastic deformation occurs in the edge region, which acts in the range of 50 micrometers to 2 millimeters from the surface, depending on the material, tool and process parameters. One of the main targets of rolling is the levelling of the surface. This reduces the notch effect in the roughness behavior, which has a positive effect on the service life.

Furthermore, during the course of the roughness reduction, a pure flattening of the roughness points and a complete remodelling of the surface can be distinguished. Thus, the surfaces of components of different materials having different mechanical properties can be modified to a large extent as long as a sufficient ratio is provided between the process-induced load stress and the yield limit of the component.

Furthermore, deep rolling enables the introduction of internal stresses. The appropriate relationship of the introduced internal stress to the superposition of loading stresses caused by the loading of the component can be used to retard crack growth and reduce crack growth rate to increase the vibration resistance of the component.

In addition to the quantitative increase in internal stress, the characteristics of the internal stress depth profile (depending on the hardness of the material being processed) also affect the performance of the part in use. For soft materials, the internal stress depth profile is determined by plastic stretching, while for hardened materials, the internal stress depth profile is determined in the form of Hertz compression. By adjusting the mechanical load, the rolled body diameter and the coverage, the characteristics of the internal stress depth profile can be significantly affected.

The rolling force required during deep rolling and/or flattening rolling depends on the penetration depth required and the material and material conditions and can range in value from above 0N to 2,000N. The rolling force may be applied by mechanical, spring-loaded or hydrostatic systems.

Possible rolling bodies are rolls in the form of balls or cylindrical rollers or tapered rolling elements, which must have a higher hardness than the material to be worked. These rolling bodies are classified according to their radii. Suitable radii for deep rolling and/or flattening rolling are between 3 mm and 15 mm.

According to the invention, such deep rolling is interwoven with bend straightening in terms of process flow technology, however, the individual steps remain functionally independent of each other, i.e. they are not interdependent. In other words, the various areas of the drive shaft 1 can be machined by deep rolling, whether or not the straightening of the drive shaft is performed in these areas or not at all. Vice versa, bending straightening can be performed where deep rolling is not required.

According to the invention, both process steps are performed in the same clamping of the drive shaft 1, thereby saving additional process time for re-clamping the drive shaft 1.

As previously mentioned, the straightness of the drive shaft is first checked before the actual straightening. This straightness measurement of the drive shaft 1 is a prerequisite for the subsequent bend straightening, since in this case the degree of correction required is determined.

According to the invention, the drive shaft 1 is clamped in the bend straightener after hardening. In this bend leveler, the drive shaft 1 is also deep rolled in the region a of the welded joints 14a,14b of the mutually welded sections 10, 11a,11b.

In other words, straightness measurement and deep rolling for bend straightening of the drive shaft 1 are performed in the same clamping device of the drive shaft 1 in the bend straightener.

The deep rolling and bend straightening processes may be performed continuously and sequentially. For this purpose, for example, the region a of the welded joint 14a,14b can be first processed by deep rolling, followed by straightness measurement and subsequent bend straightening. In principle, the order can also be reversed, i.e. straightness measurement and bend straightening are performed before deep rolling.

Typically, the rotation of the drive shaft 1 about its longitudinal axis B is used both for straightness measurement to detect dimensional deviations in the bend leveler and for deep rolling of welded joints.

However, instead of a strict serial or sequential sequence, it is also possible to start the straightness measurement during the rolling process even before this. In this case, the bend straightening can also be carried out in the bend straightener after the deep rolling and after the straightness measurement in the clamping for the deep rolling.

In the context of a method for producing a multi-part welded drive shaft, such as in particular the longitudinal and transverse shafts of a motor vehicle, this enables a virtually process-time-balanced integration of the intensified deep rolling into the process steps of the shaped bend straightening.

As a further process step, tempering of the drive shaft 1 may optionally be connected after deep rolling and bending rolling.

The method described above is particularly suitable for mass production of drive shafts 1 in the automotive industry and, due to its flexibility, for rapid and efficient prototype construction and evaluation.

Fig. 2 shows a possible embodiment of a bend straightener 20 with integrated tools for deep rolling.

The bend straightener 20 according to fig. 2 firstly comprises at least one support 21 on which support 21 the drive shaft 1 or a conventional shaft is supported rotatably about its longitudinal axis B in a lateral direction. In the embodiment shown, there are two abutments 21 as an example.

Furthermore, a drive device 22 is provided for rotating the shaft 1 about its longitudinal axis B, which drive device 22 is realized by means of spindle clamping in the embodiment of fig. 2. By clamping the spindle 1 axially between the two spindles, a drive torque is introduced into the spindle 1.

Further, the bend leveler 20 includes a device 23 for measuring the straightness of the shaft 1, by which dimensional deviations, for example, due to hardness distortion or the like, can be detected when the shaft 1 rotates about its longitudinal axis B.

Further, a device 24 for straightening the shaft is provided on the bend straightener 20. For example, the device may exert force F _B Is pressed laterally against the shaft 1, while the shaft 1 is supported on at least one abutment 21. For this purpose, only one ram or tappet is shown in this example, which presses the shaft 1 in the center of the shaft. However, a plurality of such devices 24 may also be provided, anddistributed along the length of the shaft 1.

Furthermore, the bend leveler comprises a roll or roller 25 as a deep rolling tool, which roll or roller 25 is arranged opposite the respective stand 21.

Furthermore, a pressure device 26 is provided, which is adapted to apply a rolling force F _w The rolls or rollers 25 are pushed towards the respective seats 21 so that the rolls or rollers 25 can be deep rolled in lateral contact with the shaft 1.

Suitable feeding means allow the roller or rolls 25 to be moved in the longitudinal direction of the shaft 1 so that a range of axial lengths required for the deep rolling process can be obtained. Furthermore, means may be provided for moving the rollers or rollers 25 radially away from the shaft 1 and towards the shaft 1 in order to engage and disengage the means for securing the rollers with the shaft 1.

In the bending straightening of the preferred rotational symmetry axis, the shaft 1 is placed on the support 21. The abutment is located in the region of the weld joints 14a,14b and is for this purpose movably arranged in the bend leveler.

The shaft 1 is then rotated. For example, during rotation, the straightness of the shaft 1 is measured using a sensor.

For bend straightening, the shaft 1 is directed upwards with a maximum deviation and is plastically deformed by a punch or the like, wherein, in short, the shaft is bent relatively slightly to counteract the deviation. Thus, the shaft 1 is more straight than before the method.

In the bend leveler 20, deep rolling is performed in the region of the welded joints 14a and 14 b. Thus, the shaft 1 is still supported on the support 21. During rotation and straightness measurements, deep rolling is performed in the weld area. Thus, during the measurement, plastic deformation and strengthening outside the measurement range have occurred.

Then the rolling force F is removed _w . The roll or rollers 25 leave the shaft 1 and the actual bend straightening process starts.

In this combined process of bend straightening and deep rolling on a multi-piece welding shaft 1, the two processes are locally separated from each other and do not interact as effectively as in straightening rolling. In contrast, the two processes run in parallel in a single clamping device, but have largely no interaction.

The rotation process is used for realizing the straightness measurement of feeding f and bending straightening during deep rolling. After the defined area has been fully strengthened by the deep rolling method, the rolling tool leaves the part and starts the straightening forming, in this case preferably in the centre of the central section 10 of the drive shaft 1.

The deep rolling of the two areas a of the weld joints 14a,14b can be performed simultaneously, in particular because in the example shown the active areas are virtually identical. The abutment 21 is used to support the corresponding reaction forces during rolling and bend straightening.

In this case, the feed f is understood to be the relative movement of the deep rolling between the drive shaft 1 and the rolling body in the direction of the longitudinal axis B of the drive shaft 1. In deep rolling with rotational kinematics, the coverage relates the feed f to the pressed-in width of the rolled body and determines the surface topography resulting therefrom and the number of revolutions of the process. Here, coverage of-100% to +100%, preferably-50% to +50% may be used. Negative coverage means that successive windings of the resulting encircling rolling trajectory are axially spaced apart from each other.

In contrast to conventional machining, the rotational speed determines not only the influence of the edge region, taking into account the feed f and the rolling speed, but also plays a decisive role in the measurement accuracy of the tactile measurement of the bend straightening. Rotational speeds from 0 rpm to 5,000 rpm may be used depending on the size of the components.

FIG. 3 shows another embodiment of a bend leveler 20', which bend leveler 20 differs from the bend leveler 20 of FIG. 3 at least in the tools and rotational drives used for deep rolling.

In fig. 3, a tool 27 having rolling elements arranged 360 ° around the circumference of the shaft 1 performs a rolling process (including support of the shaft 1).

For example, the rotation of the shaft 1 may be achieved by a clamping device 28 similar to the chuck of a cutting machine. As shown in fig. 3, the shaft 1 can be clamped at only one end to the clamping device 28 for this purpose.

For bend straightening, a device similar to the devices 22, 23 and 24 in fig. 2 can be used, but other devices such as those explained at the outset can also be used, as long as the shaft 1 is not clamped between deep rolling and bend straightening.

The above embodiments effectively integrate measures for increasing the reinforcement of the drive shaft for multi-component welding by avoiding the increase of process time and additional process stations.

Furthermore, these embodiments enable simultaneous bend straightening during deep rolling in different operating areas in the bend straightener.

The invention is explained in more detail above by means of examples and further variants. The examples and variants serve to demonstrate the feasibility of the invention. The technical features explained above in the context of other features can also be implemented independently of these features and in combination with other features, even if not explicitly described, as far as technically possible. Therefore, the present invention is expressly not limited to the specifically described embodiments and variants, but includes all technical solutions defined by the claims.

List of reference numerals

1 drive shaft (shaft)

10 center section

11a end section

11b end section

12a coupling structure

12b coupling structure

13a hollow shaft section

13b hollow shaft section

14a welded joint

14b welded joint

15 welding bead

20 bending straightener

20' bending straightener

21 support

22 drive device

23 straightness measuring device

24 means for straightening

25 rolls or rollers

26 pressure device

27 deep rolling tool

28 clamp device

A area around the weld joint

B longitudinal axis of drive shaft (shaft), corresponding to rotation axis

F _B Bending force

F _W Rolling force

f, feeding.

Claims

1. Method for producing a drive shaft (1), which drive shaft (1) has at least two sections (10, 11a,11 b) welded to one another in a material-bonded manner, wherein at least one of the sections is designed as a hollow shaft, wherein deep rolling is performed in the region of the welded joints (14 a,14 b) of the sections welded to one another, characterized in that the deep rolling is performed in a bend straightening machine (20, 20 '), wherein the straightness measurement of the drive shaft (1) for the bend straightening of the drive shaft and the deep rolling are performed in the same clamping device in the bend straightening machine (20, 20').

2. Method according to claim 1, characterized in that the rotation of the drive shaft for straightness measurement for checking dimensional deviations is used for deep rolling in a bend leveler (20, 20') for the welded joint (14 a,14 b).

3. A method according to claim 1 or 2, characterized in that the straightness measurement has been started in time during deep rolling.

4. A method according to one of claims 1 to 3, characterized in that in the bend leveler (20, 20') in the clamping apparatus for deep rolling, the bend leveling is performed after deep rolling and after measuring the straightness.

5. Method according to one of claims 1 to 4, characterized in that the drive shaft (1) is hardened before deep rolling and/or tempered after deep rolling.

6. Method according to one of claims 1 to 5, characterized in that the weld beads (15) of the welded joint (14 a,14 b) are removed in a cutting manner before deep rolling.

7. Method according to one of claims 1 to 6, characterized in that the drive shaft (1) is rotatably supported in the bend-straightening machine (20) on a lateral support (21) for bend-straightening, and that the deep-rolled rolls or balls (25) are arranged opposite the support (21) and are pressed laterally against the drive shaft (1) in the direction of the support (21) during deep rolling.

8. Method according to one of claims 1 to 6, characterized in that a deep rolling tool (27) is provided which surrounds the drive shaft (1) in a ring-shaped manner, which deep rolling tool (27) also rotatably supports the drive shaft (1).

9. Method according to one of claims 1 to 7, characterized in that the drive shaft (1) has a central section (10) in the form of a hollow shaft and end sections (11 a,11 b) connected to its ends, which end sections each have a coupling structure (12 a,12 b) for transmitting torque.

10. A bend straightener (20, 20') comprising:

at least one support (21) on which the shaft (1) is supported laterally and rotatably about its longitudinal axis (B),

a drive device (22) for rotating the shaft (1) about its longitudinal axis (B),

means (23) for measuring the straightness of the shaft (1),

means (24) for straightening the shaft (1) when the shaft (1) is supported on at least one support (21),

it is characterized in that the method comprises the steps of,

a roller or a roller (25) arranged opposite the support (21), and

pressure means (26) adapted to push the roller or rollers (25) in the direction of the abutment (21) so that the roller or rollers (25) can be laterally abutted against the shaft (1) for deep rolling.

11. A drive shaft (1) for a motor vehicle, which drive shaft has at least two sections (10, 11a,11 b) welded to one another in a material-bonded manner, at least one of which is designed as a hollow shaft, characterized in that the drive shaft (1) is tempered at a welded joint (14 a,14 b) between the two sections (10, 11a,11 b) welded to one another in a material-bonded manner, the drive shaft having a machined surface and a deep-rolled surface structure with internal stresses formed in the radially outer edge region.