DE102020203101A1 - Method for producing a steering shaft part of a steering shaft for a motor vehicle, method for producing a steering shaft for a motor vehicle, steering shaft part for a steering shaft for a motor vehicle, steering shaft for a motor vehicle and steering column for a motor vehicle - Google Patents

Abstract

The present invention relates to a method for manufacturing a steering shaft part (10) of a steering shaft (1) for a motor vehicle, which has a tubular steering shaft section (2) extending from an end face (41) in a longitudinal direction, which is located in a tubular steering shaft section (2) from the end face ( 41) has a connecting section (21) over a partial section of the steering shaft section (2) extending end section which, at least over part of its length, has an enlarged wall thickness (22) compared to a section of the steering shaft part (10) adjoining the connecting section (21), comprising the steps of - providing a pipe section (4), - generating an increase in wall thickness (22) by reshaping at least in sections in the end section extending from the end face (41) to form the connecting section (21). In order to enable the provision of a steering shaft part (10) and a steering shaft (1) constructed therefrom and a steering column with less effort and high safety, the invention proposes that the increase in wall thickness (22) be produced by plastic deformation of the end section of the pipe section (4) done by tumbling.

Description

State of the art

• - Bereitstellen eines Rohrabschnitts,
• - Erzeugen einer Wandstärkenvergrößerung durch zumindest abschnittweise Umformung in dem sich von der Stirnseite erstreckenden Endabschnitt zur Ausbildung des Verbindungsabschnitts.

The invention relates to a method for producing a steering shaft part of a steering shaft for a motor vehicle, which has a tubular steering shaft section which extends in a longitudinal direction from an end face and which has a connection section in an end section extending from the end face over a partial section of the steering shaft section, which at least over a part of its length has a wall thickness enlargement compared to a section of the steering shaft part adjoining the connecting section, comprising the steps

• - Provision of a pipe section,
• - Generating an increase in wall thickness by at least section-wise reshaping in the end section extending from the end face to form the connecting section.

The invention also relates to a method for producing a steering shaft and a steering column for a motor vehicle, as well as a steering shaft part for a steering shaft for a motor vehicle, a steering shaft and a steering column for a motor vehicle.

A steering system of a motor vehicle has a steering shaft for connection to the steering gear in order to transmit a steering torque, for example a steering command entered manually into a steering wheel. The steering shaft is usually formed from steering shaft parts that are rotationally coupled to one another. These can be adjusted telescopically relative to one another in order to adapt to the spatial conditions, to compensate for displacements in the event of a crash and to adjust the steering wheel position in the longitudinal direction, i.e. in the direction of their longitudinal axis, and can be connected in an articulated manner to compensate for angular misalignment. On the rear part of the steering shaft relative to the direction of travel, mostly on the steering spindle mounted in the steering column, the steering wheel is fixed to its rear end section facing the driver's position.

A generic steering shaft part can be designed continuously as a hollow shaft, which extends in a longitudinal direction determined by its longitudinal axis and can be designed, for example, as a hollow cylinder or with a polygonal hollow cross-section, or at least have a steering shaft section extending from an end face, which is similarly designed as a tubular or hollow shaft section can be formed. To fix the steering wheel, or for torque-locking connection to other steering components such as joints, gears, auxiliary power drives or the like, an end section, which extends as a partial section of said steering shaft section from the end face in the longitudinal direction, is designed as a connecting section, which is also referred to as a coupling section.

In order to be able to implement suitable fastening means, for example form-locking elements, clamping sections or the like, it is known to provide an enlargement of the wall thickness in the connecting section, at least in sections, which includes an area with a wall thickness that is greater than the length of the rest of the steering shaft or the steering shaft section. Outside the connecting section, the steering shaft can be thinner-walled, which has the advantage that mass can be saved, and yet sufficient torsional rigidity is ensured.

To generate an increase in wall thickness on a steering shaft part, it is, for example, from the WO 2007/098513 A1 or the DE 10 2016 214 163 A1 known to insert an additional sleeve at the end of a relatively thin-walled pipe section and to fix it in the connecting section in a non-detachable manner by forming together, for example positively and non-positively by means of cold forming processes such as hammering or kneading. It is advantageous here that a sufficient increase in wall thickness can be generated by adding the wall thicknesses of the pipe section and sleeve. However, it is disadvantageous that the sleeve has to be prefabricated separately and must be securely fixed in a further production step because of the high safety requirements, which leads to a relatively high production outlay.

In view of the problems explained above, it is an object of the present invention to make it possible to provide a steering shaft part and a steering shaft constructed therefrom and a steering column with less effort and high safety.

Presentation of the invention

This object is achieved according to the invention by the method according to claim 1, the method according to claim 7, the method according to claim 8, and the steering shaft part with the features of claim 9, the steering shaft with the features of claim 10, and the steering column with the features of Claim 12. Advantageous developments result from the subclaims.

• - Bereitstellen eines Rohrabschnitts,
• - Erzeugen einer Wandstärkenvergrößerung durch zumindest abschnittweise Umformung in dem sich von der Stirnseite erstreckenden Endabschnitt zur Ausbildung des Verbindungsabschnitts,

wird erfindungsgemäß vorgeschlagen,
dass das Erzeugen der Wandstärkenvergrößerung durch plastische Umformung des Endabschnitts des Rohrabschnitts durch Taumelstauchen erfolgt.In a method for producing a steering shaft part of a steering shaft for a motor vehicle, which has a tubular shape extending from an end face in a longitudinal direction Has steering shaft section which in an end section extending from the end face over a section of the steering shaft section has a connecting section which, at least over part of its length, has a wall thickness enlargement compared to a section of the steering shaft part adjoining the connecting section, comprising the steps

• - Provision of a pipe section,
• - Generating an increase in wall thickness by at least section-wise deformation in the end section extending from the end face to form the connecting section,

is proposed according to the invention,
that the increase in wall thickness is produced by plastic deformation of the end section of the pipe section by means of wobble upsetting.

A tube section is provided as the starting material in the manufacture of the steering shaft section, which tube section preferably has a given, uniformly continuous wall thickness, for example by cutting to length from a continuous tube semi-finished product, preferably made of steel. According to the invention, the wall thickness in a connecting section is increased in relation to the wall thickness of the starting material in this pipe section exclusively by plastic deformation, whereby a wall thickness increase in sections in the longitudinal direction, which can also be referred to as a wall thickening, is generated. This deformation takes place without cutting and essentially preserving the volume by flowing the material of the pipe section under high deformation pressure, for example by cold extrusion. The increase in wall thickness is preferably carried out exclusively by plastic deformation of the pipe section by wobble upsetting.

According to the invention, in contrast to the prior art, no additional material is required to produce the connecting section. This results in the advantage that a sleeve or the like does not have to be produced and assembled separately as in the prior art, so that the production effort can be advantageously reduced.

The one-piece construction of the enlargement of the wall thickness according to the invention has the further advantage that there are no joints that are unavoidable in the prior art due to the additionally inserted material. In this way, according to the invention, the rigidity and load-bearing capacity of the connecting section can be increased in an advantageous manner.

Another advantage of the purely plastic deformation according to the invention is that an uninterrupted microstructure can be formed in the area of the increase in wall thickness, whereby the strength and toughness of the material in the connecting section can be increased. This makes it possible to make the connecting section more compact without any safety restrictions, and to reduce the wall thickness of the steering shaft section in order to save material and mass.

The wobble upsetting used according to the invention to generate the increase in wall thickness enables specific advantages in the manufacture of a steering shaft part. A plastic deformation of a tubular component by simply upsetting it in the longitudinal direction can lead to a deformation and flow of the material that is difficult to control, especially when the wall thickness of the tubular starting material is relatively thin. This can lead to structural disturbances and, in the case of large deformation ratios, to the formation of cracks or the like, so that use for the production of highly safety-relevant steering components is expensive and unsuitable.

The aforementioned disadvantages can be solved by the tumble-upsetting used according to the invention. Instead of an axial upsetting force simultaneously exerted on the entire pipe cross-section, a wobble tool, namely a wobble die, which is inclined with respect to the longitudinal axis, creates a partial press contact that extends only over part of the circumference of the annular end face of the pipe section. The wobbling movement of the wobble die is generated by a cyclical, circular movement of the die axis along a conical surface converging in the longitudinal direction. As a result of the wobbling, the wobble die is rolled several times over the circumference on the end face of the pipe section in press contact in one operation, and at the same time the wobble die is pressed with the forming force in the longitudinal direction against the end face. The pipe wall is rolled around the circumference on the front side and the material is plastically displaced in the rolling direction. This dynamic application of the forming force brings about a controlled flow of the material in the pipe wall in the circumferential direction as well as in the longitudinal direction and in the radial direction. The advantage here is that structural disturbances, crack formation and the like can be reliably avoided, largely independently of the deformation ratio.

The tumble upsetting can preferably be carried out in one operation which comprises a multiple tumbling movement in combination with a working stroke in the longitudinal direction. Of the The working stroke corresponds to the compression path, that is to say the distance in the longitudinal direction by which the pipe section is compressed or shortened during the forming to produce the thickened connecting section. One advantage of the method according to the invention is that a deformation ratio that is sufficient to generate the increase in wall thickness can be achieved in a single working stroke. This enables efficient production.

With wobble upsetting, a manageable and efficient manufacturing process specifically for steering shaft parts is made available for the first time, which advantageously enables an increase in wall thickness to be generated efficiently and with optimized material properties in one operation by combined tumbling and upsetting. As a result, a durable and highly resilient connection section can be provided on the steering shaft part in an advantageous manner. As a result of the tumble upsetting, optimized material properties and flexible shaping can be realized in the same way, which in the prior art are not possible or only possible with a disproportionately high effort.

Thanks to the method according to the invention, the increase in wall thickness can advantageously be implemented on a relatively thin-walled pipe section.

The increase in wall thickness is preferably between 5% and 50% of the original wall thickness (material thickness), particularly preferably between 10% and 30%. For example, the wall thickness of the pipe section can be increased from 2 mm before the tumble upsetting to 2.5 mm after the tumble upsetting, the pipe section having an outside diameter of, for example, 30 mm.

In an advantageous development, the steering shaft part is formed from a metallic material, for example from a steel, in particular a high-strength, low-alloy steel. Alternatively, it is conceivable and possible that the steering shaft part is formed from a light metal alloy, such as an aluminum alloy.

With the method according to the invention, a plastic increase in the wall thickness of a pipe section can be realized in a connecting section, the outer diameter of the pipe section and the connecting section being the same, at least essentially the same, after the increase in the wall thickness is formed. As a result of the wobble upsetting, the material of the pipe section is plastically displaced axially, i.e. in the longitudinal direction and at the same time radially inwards. As an alternative or in addition, it is conceivable and possible to enlarge the outer diameter of the pipe section in the area of the increase in wall thickness according to the invention by means of tumbling.

With tumble upsetting, a tumble die rotating about an axis inclined to the longitudinal direction (tumble axis) can be pressed against the end face in a cyclical rolling motion, with the material flowing in the circumferential direction, in the longitudinal direction and in the radial direction. The wobble die is preferably designed to be rotationally symmetrical and has an end face stamp or pressing surface which is pressed against the end face of the pipe section for deformation. Due to the fact that the wobble die is inclined against the longitudinal direction, i.e. the longitudinal axis of the pipe section, the die surface rests only over part of the circumference in a press contact against the end face of the pipe section. For the wobbling movement, the inclined wobble axis of the wobble die revolves along a conical jacket which is coaxial to the longitudinal axis and which conically converges towards the end face of the pipe section. During one revolution, the punch surface is rolled once over the entire circumference over the end face of the pipe section in press contact in the circumferential direction. The wobble die is loaded in the longitudinal direction by the axial upsetting force during a plurality of circular tumbling movements and moved around the upsetting path, with successive, uniform deformation taking place in the manner described above in the successive tumbling movements.

It is advantageous that the pipe section is received in a die assembly during wobble upsetting, which has a die sleeve surrounding at least the end section of the pipe section with an opening at the end, and a die mandrel that plunges into the pipe section, the pipe section being received between the die mandrel and the die sleeve and an annular space corresponding to the wall thickening is provided between the die mandrel and the die sleeve. This annulus extends longitudinally from the opening. The die sleeve, synonymous briefly referred to as sleeve, and the coaxially arranged die mandrel, or mandrel for short, delimit the hollow cylindrical mold cavity, the so-called cavity, which has the contour of the finished steering shaft part. Outside the connecting section, a pipe section is received with little play between the sleeve and the mandrel, so that the pipe wall is supported in the radial direction. In an end section of the cavity that is axially open in the longitudinal direction, the outer cross section of the mandrel is reduced or the inner cross section of the sleeve is increased so that the annular space that remains free there has a larger radial dimension. The enlarged annulus corresponds to the dimensions of the increase in wall thickness.

To carry out the method according to the invention, the pipe section is inserted between the mandrel and the sleeve. Then a wobble die is set in wobbling motion and inserted in a working stroke in the longitudinal direction through the front opening of the die sleeve and pressed against the front side of the end section of the pipe section accommodated in the area of the enlarged annular space. Due to the plastic roll deformation applied due to the tumbling movement, the wall is compressed in the end area and the material flows in the longitudinal, radial and circumferential directions until the enlarged annular space of the die is completely and evenly filled. In this way, the wall thickening is produced solely by plastic deformation of the wall of the pipe section. After the forming process, the wobble die can be withdrawn against the working stroke, and the steering shaft part with the connecting section can be removed from the die.

The high strength and the uniform structure of the wall thickening, which can be realized by the method according to the invention in the above-described die arrangement, are advantageous. Larger dimensions of the connecting section in the longitudinal direction can also be produced in one operation.

An advantageous embodiment can provide for the die mandrel to be lowered in the longitudinal direction relative to the die sleeve, as seen from the end face, during wobble upsetting. For this purpose, it can be provided that the mandrel is mounted in the sleeve so as to be movable in the direction of the working stroke, and is preferably supported in the longitudinal direction in a resilient manner relative to the sleeve. When it is pressed against the end face, it compresses the pipe section and, in doing so, lies against the mandrel at the end face. As a result, the wobble die moves the mandrel in the direction of the working stroke by the amount of the shortening of the pipe section, so that the plastically compressed end section is completely within the mold cavity closed by the mandrel, sleeve and wobble die during the entire forming process. This has the advantage that uncontrolled deformations are practically excluded and a consistently high manufacturing quality is guaranteed.

It is possible for at least one form-locking element to be formed during wobble upsetting. A form-locking element can be integrally molded or molded into the connecting section with the material thickening of the wall thickness enlargement, which can have projections, depressions, one or more threads or the like molded onto or from the inside and / or outside, such as, for example, a toothing for the rotationally locking connection of the Steering shaft with a steering component such as a joint, a gearbox, an auxiliary power drive, a steering wheel or the like. The advantage of the wobble upsetting according to the invention is also that more complex shapes of connecting means or the like can be produced efficiently, precisely and highly stressable and in one operation. For practical implementation, for example, the above-described mandrel and / or the sleeve can have negative contours which correspond to the form-fit elements to be formed in the connecting section.

It is possible for the pipe section and / or the connection section to have a round cross section or a non-round cross section. Like the steering shaft part, the pipe section can be designed as a hollow cylinder, and so can the connecting section. Alternatively, a non-circular or polygonal cross section can be implemented in the connecting section, for example by using a die mandrel which is prismatic on the outside at least in sections. Alternatively or additionally, the inside of the die sleeve can have an at least partially non-circular or polygonal cross-section in order to produce a corresponding outer cross-section of the connecting section.

In an advantageous development, it can be provided that after the generation of the enlargement of the wall thickness of the end section, an internal thread is introduced and / or an external thread is applied in this end section. For example, it is possible for the end section to be connected to a steering wheel by means of a fastening means such as a screw or a nut. Thanks to the invention, the thread can be introduced directly into the material of the end section of the steering shaft part, and it is not necessary, as in the prior art, to work a separate sleeve into the end section.

In a further advantageous development, it is possible for the end section to have external form-fitting elements which are formed in the end section by the method according to the invention, the end section additionally being provided with an internal thread. Thus, a steering wheel with a hub, which has an internal form-locking element corresponding to the outer form-locking elements of the end section, can be coupled to the steering shaft part in a torque-locking manner, with a fastening means in the form of a screw being brought into operative engagement with the internal thread of the end section and thus the steering wheel on the Steering shaft part determines.

An advantageous method for producing a steering shaft for a motor vehicle, in which at least two steering shaft parts are provided and rotationally connected to one another, provides according to the invention that at least one of the steering shaft parts is produced by a method according to one or more of the embodiments described above, and with at least one further steering shaft part is connected. Further steering shaft parts can include, for example, steering shaft components, such as, for example, a further steering shaft section, a joint, a transmission, an auxiliary power drive, a steering wheel or the like. The method according to the invention enables the steering shaft parts to be provided efficiently and with advantageous properties, which is also advantageous for a steering shaft formed therefrom. For example, through the wobble upsetting, a higher strength and thus a higher rigidity can be achieved with smaller dimensions of the steering shaft parts, so that a lower weight and / or a smaller size of the steering shaft can be realized.

An advantageous method for producing a steering column for a motor vehicle, in which at least two steering shaft parts are provided and rotationally connected to one another, provides according to the invention that at least one of the steering shaft parts of the steering shaft is produced by a method according to one or more of the embodiments described above, and the Steering shaft is mounted rotatably mounted around the longitudinal axis in a jacket unit. By means of the method according to the invention, the steering shaft parts and a steering shaft formed therefrom can be provided efficiently and with advantageous properties, which is also advantageous for a steering column having them. For example, through the wobble upsetting, a higher strength and thus a higher rigidity can be achieved with smaller dimensions of the steering shaft parts, so that a lower weight and / or a smaller structural size of the steering column can be realized.

In the case of a steering shaft part for a steering shaft for a motor vehicle, which has a hollow shaft which, at least at one end section, has a connecting section which, at least over part of its length, has an increase in wall thickness compared to a section of the hollow shaft adjoining the connecting section, the invention provides that the enlargement of the wall thickness is formed in one piece with the hollow shaft exclusively by plastic deformation of the material in the end section by wobble upsetting according to one of the methods described above.

The hollow shaft is formed by a tubular steering shaft section which is produced according to the method according to the invention. A relatively large deformation ratio can be generated by the wobble upsetting, and an optimized microstructure and a higher strength of the connecting section can be achieved by the optimized deformation.

A steering shaft part according to the invention can, for example, comprise a steering shaft component, such as, for example, a further steering shaft section, a joint, a transmission, an auxiliary power drive, a steering wheel or the like, or be designed as part of such.

In a steering shaft according to the invention, it is preferably provided that at least two steering shaft parts are connected to one another in a rotationally locked manner. The advantageous properties and effects described can already be achieved by designing at least one of the steering shaft parts according to the invention.

In the case of a steering column for a motor vehicle, comprising at least two steering shaft parts that are rotationally connected to one another, the invention provides that at least one of the steering shaft parts of the steering shaft is produced by a method according to one or more of the embodiments described above. The described advantages of the steering shaft according to the invention can thereby also be used for a steering column.

In the case of a steering column for a motor vehicle, comprising at least one steering shaft part, it is provided according to the invention that the steering shaft part of the steering shaft is produced by a method according to one or more of the embodiments described above. The described advantages of the steering shaft according to the invention can thereby also be used for a steering column.

It can be advantageous for at least one steering shaft part to be mounted rotatably about the longitudinal axis in a jacket unit of the steering column designed for connection to a motor vehicle body. For example, a steering spindle can be designed according to the invention. The connecting section can be set up and designed to attach a steering wheel or another steering component, for example a joint for connecting the steering spindle to an intermediate shaft.

Figure list

• 1 eine schematische perspektivische Ansicht einer Lenkwelle,
• 2 einen Längsschnitt durch einen Rohrabschnitt,
• 3 einen Längsschnitt durch ein einen erfindungsgemäßen rohrförmigen Lenkwellenabschnitt,
• 4 eine Gesenkanordnung und einen Taumelstempel zur Herstellung eines erfindungsgemäßen Lenkwellenabschnitts gemäß 3,
• 5 die Anordnung gemäß 4 in einer teilweise auseinander gezogenen Darstellung,
• 6 einen Längsschnitt durch die Anordnung gemäß 4,
• 7 eine Detailansicht des Längsschnitts gemäß 6 vor der Durchführung des erfindungsgemäßen Taumelstauchens,
• 8 eine Detailansicht des Längsschnitts wie in 7 während des erfindungsgemäßen Taumelstauchens,
• 9 eine Detailansicht des Längsschnitts wie in 8 nach der Durchführung des erfindungsgemäßen Taumelstauchens.

Advantageous embodiments of the invention are explained in more detail below with reference to the drawings. Show in detail:

• 1 a schematic perspective view of a steering shaft,
• 2 a longitudinal section through a pipe section,
• 3 a longitudinal section through a tubular steering shaft section according to the invention,
• 4th a die assembly and a wobble die for producing a steering shaft section according to the invention according to FIG 3 ,
• 5 the arrangement according to 4th in a partially exploded view,
• 6th a longitudinal section through the arrangement according to 4th ,
• 7th a detailed view of the longitudinal section according to 6th before performing the tumble diving according to the invention,
• 8th a detailed view of the longitudinal section as in 7th during tumble diving according to the invention,
• 9 a detailed view of the longitudinal section as in 8th after the tumble diving according to the invention has been carried out.

Embodiments of the invention

In the various figures, the same parts are always provided with the same reference numerals and are therefore usually only named or mentioned once.

1 shows a steering shaft designed according to the invention 1 in a schematic perspective illustration. This includes one in the direction of a longitudinal axis L. extended steering shaft 11 that has a first universal joint 12th with an intermediate shaft 13th connected to another universal joint 14th connected.

The steering shaft 11 comprises a steering shaft part designed as a hollow shaft 10 , in the steering shaft side an inner shaft 3 in the direction of the longitudinal axis L. telescopically immersed, as indicated by the double arrow. The inner shaft 3 has a non-circular outer cross-section, which can for example have a polygonal or cloverleaf-shaped profile, and in one for this with respect to rotation about the longitudinal axis L. Corresponding section of the steering shaft part in a form-fitting cross-section 10 immersed in a known manner.

The steering shaft part 10 has a tubular, in the example shown hollow-cylindrical steering shaft section 2 on. In an end section, which points to the left in the drawing, this tubular steering shaft section 2 a connecting section 21 on. In the in 3 shown longitudinal section along the longitudinal axis L. it can be seen that the connecting section 21 an increase in wall thickness 22nd has, also known as a wall thickening, with a wall thickness D. . Outside the connection section 21 the wall is thinner with a wall thickness d , where the following applies: d <D.

2 shows in the same sectional view as 3 a pipe section 4th , which is used as the starting material or semi-finished product for the production of a steering shaft section according to the invention 2 serves. The pipe section 4th has an evenly continuous wall thickness d , and is cut to length, for example, from a continuous steel pipe material. An axial end face 41 is located at its free end.

The increase in wall thickness 22nd is by tumbling the pipe section according to the invention 4th around the compression path s have been produced in one piece, therefore the steering shaft part 2 in the longitudinal direction around this compression path s shorter than the pipe section 4th , as in 3 in comparison with 2 is indicated. The pipe section has a length L1 measured in the direction of the longitudinal axis L. on and the steering shaft part 2 has a length L2 measured in the direction of the longitudinal axis L. on, with the compression path s results from the difference between the length L1 and the length L2. The compression path s is measured between the end face 41 of the pipe material 4th , which is identical to the end face 41 of the steering shaft section 2 . In the 3 is the original length of the pipe section 4th indicated schematically with the dashed line.

A device for carrying out the method according to the invention is shown in a perspective view in FIG 4th , in longitudinal section in 6th , and in 5 shown in an exploded view in the longitudinal direction.

The device comprises a wobble die 5 and a die assembly 6th . The die assembly 6th has an open die sleeve 61 with an opening at the front 610 and a die mandrel coaxially disposed therein 62 on. The die sleeve 61 is on her of the opening 610 facing away from the base on a base 63 permanently mounted on which the die mandrel 62 by a spring element 64 is supported elastically movable in the longitudinal direction, as in 6th is indicated by the arrow. The die mandrel 62 is also briefly called a thorn 62 and the die sleeve 61 is also briefly called a sleeve 61 designated.

The internal cross-section of the die sleeve 61 and the outer cross-section of the die mandrel 62 are dimensioned so that the radial distance in the annular space formed is approximately the same as the wall thickness d corresponds so that the pipe section 4th can be received therein coaxially with little play, as in 6th until 9 is recognizable.

From the enlarged sectional views of 7th , 8th , 9 it can be seen that the thorn 62 in his of the mouth 610 facing end area has a partially reduced cross-section, so that between the mandrel 62 and sleeve 61 a greater radial distance D. remains that of the increased wall thickness D. the increase in wall thickness 22nd is equivalent to. This forms a mold cavity 65 with an enlarged cross section.

At the start of the method according to the invention, a pipe section 4th into the die assembly between the sleeve 62 and the thorn 61 used as in 7th shown. With its wall thickness d fills the pipe section 4th the space between the mandrel 61 and the sleeve 62 outside of the mold cavity 65 essentially from, while the mold cavity 65 is not completely composed of the material of the pipe section 4th is filled.

The tumbler 5 is set in a tumbling motion, in which the against the longitudinal axis L. inclined axis T (Wobble axis) of the wobble die 5 the longitudinal axis L. along a cone shell, which is in the direction of the die assembly 6th to converge lengthways, circled as in 4th and 5 is drawn.

Starting from 7th becomes the tumbler 5 lengthways through the opening 610 into the sleeve 62 introduced and at the front with a forming or upsetting force F. against the die 61 pressed on, i.e. in 7th downward. The spring supported thorn 61 evades downwards until the tumbler 5 the end face 41 of the pipe section 4th in a press contact K contacted. The press contact K extends because of the inclined tumbler 5 only over a small part of the circumference of the end face 41 of the pipe section 4th .

The press contact runs through the tumbling movement K in the circumferential direction cyclically along the string side 41. Meanwhile, the tumble stamp 5 with the upsetting force F. pressed against the end face 41, whereby the pipe section 4th is compressed in the longitudinal direction. This is where the thorn 61 during the upsetting process by the upsetting force F. moved along and pushed down so that the upsetting force F. continue in press contact K is present. As a result of the wobble upsetting described, the material flows in the circumferential direction and at the same time in the longitudinal and radial directions. The tumbler 5 is in one working stroke by the force F. around the compression path s moved further in the longitudinal direction. As a result, the material is further plastically deformed until the entire mold cavity 65 is filled, as in FIG 9 is shown. This results in a one-piece increase in wall thickness 22nd has been formed so that a steering shaft part 2 is formed.

After the in 9 The manufacturing state shown is reached, the finished steering shaft section 2 from the die assembly 6th can be removed. This can take place, for example, by a pure longitudinal movement or by a superimposed longitudinal and rotational movement, with which a thread formed in the end section by the method according to the invention can also be demolded.

It is also conceivable and possible, for example, that the inner shaft 3 for rotationally locked connection with the joint 12th a steering shaft section 31 has, which according to the invention can be constructed and manufactured in the same way as the steering shaft section 2 . In principle, the intermediate shaft 13th be designed similar to the steering shaft 11 .

List of reference symbols

1

Steering shaft

10

Steering shaft part

11

Steering shaft

12.14

Universal joint

13th

Intermediate shaft

2

Steering shaft section

21

Connection section

22nd

Wall thickness enlargement

3rd

Inner shaft

31

Steering shaft section

4th

Pipe section

5

Tumbler

6th

Die assembly

61

Die mandrel

610

opening

62

Die sleeve (sleeve)

63

Base

64

Spring element

L.

Longitudinal axis

D.

increased wall thickness

d

Wall thickness

T

Wobble axis

s

Compression path

F.

Upsetting force (forming force)

K

Press contact

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• WO 2007/098513 A1 [0006]
• DE 102016214163 A1 [0006]

Claims (13)

A method for producing a steering shaft part (10) of a steering shaft (1) for a motor vehicle, which has a tubular steering shaft section (2) extending from an end face (41) in a longitudinal direction, which extends over a partial section from the end face (41) of the steering shaft section (2) extending end section has a connecting section (21) which, at least over part of its length, has a wall thickness enlargement (22) compared to a section of the steering shaft part (10) adjoining the connecting section (21), comprising the steps of providing a pipe section (4), - generating an increase in wall thickness (22) by at least section-wise deformation in the end section extending from the end face (41) to form the connecting section (21), characterized in that the increase in wall thickness (22) is produced by plastic deformation of the end portion of the pipe section (4) by Ta Umelstauchen takes place. Procedure according to Claim 1 , characterized in that in the wobble upsetting a wobble die (5) rotating about an axis (T) inclined against the longitudinal direction is pressed against the end face (41) in a cyclical rotating rolling movement, the material flowing in the circumferential direction, in the longitudinal direction and in the radial direction . Method according to one of the preceding claims, characterized in that the pipe section (4) is received in a die assembly (6) during wobble upsetting, which has a die sleeve (61) which is open at the end and encloses at least the end section of the pipe section (4), and a die sleeve (61) in the pipe section (4) has the die mandrel (62) immersing, the pipe section (4) being accommodated between the die mandrel (62) and the die sleeve (61) and between the die mandrel (62) and the die sleeve (61) a with the wall thickness enlargement ( 22) corresponding annular space (65) is provided. Procedure according to Claim 3 , characterized in that during wobble upsetting, the die mandrel (62) is moved in the longitudinal direction relative to the die sleeve (61) as seen from the end face (41). Method according to one of the preceding claims, characterized in that at least one form-fit element is formed during wobble upsetting. Method according to one of the preceding claims, characterized in that the pipe section (4) and / or the connecting section (21) have a round cross-section or a non-round cross-section. Method for producing a steering shaft (1) for a motor vehicle, in which at least two steering shaft parts (10, 3) are provided and rotationally connected to one another, characterized in that at least one of the steering shaft parts (10) is produced by a method according to one of the preceding Claims 1 until 6th , and is connected to at least one further steering shaft part (3). Method for producing a steering column for a motor vehicle, in which at least two steering shaft parts (10, 3) are provided and rotationally connected to one another, characterized in that at least one of the steering shaft parts (10) is produced by a method according to one of the preceding Claims 1 until 7th , and the steering shaft (1) is mounted rotatably about the longitudinal axis (L) in a casing unit. Steering shaft part (10) for a steering shaft for a motor vehicle, which has a hollow shaft (2) which at least at one end section has a connecting section (21) which, at least over part of its length, has a section adjoining the connecting section (21) the hollow shaft (2) has an enlargement of the wall thickness (22), characterized in that the enlargement of the wall thickness (22) is formed in one piece with the hollow shaft (2) exclusively by plastic deformation of the end section by wobble upsetting according to a method according to one of the preceding Claims 1 until 8th . Steering shaft (1) for a motor vehicle with at least two steering shaft parts (10, 3), at least one of the steering shaft parts (10) comprising a hollow shaft (2) which at least at one end section has a connecting section (21) which at least over part of its Length of a section of the hollow shaft (2) adjoining the connecting section (21) has a wall thickness enlargement (22), characterized in that at least one steering shaft part (10) is formed according to Claim 9 . Steering shaft after Claim 10 , characterized in that at least two steering shaft parts (10, 3) are rotatably connected to one another. Steering column for a motor vehicle, comprising at least two steering shaft parts (10, 3) which are rotationally connected to one another, characterized in that the steering shaft (1) is designed according to Claim 10 . Steering column after Claim 12 , characterized in that at least one steering shaft part (10, 3) is mounted rotatably about the longitudinal axis (L) in a jacket unit designed for connection to a motor vehicle body.

Images