DE102007018823A1 - Manufacturing hollow profile, especially hollow shafts in automobiles, involves forming profile with determined profile contour with shaping process on peripheral surface of tubular body - Google Patents

Abstract

The method involves providing a tubular body with at least one connection (13), defining an imaginary profile contour with at least one group of related undercut sections (14) in the peripheral direction of the tubular body, determining a profile contour with at least one wider section so the connection is in a region near the widened section that is uncurved or is implemented with a radius of curvature that is at least half that of the hollow profile and forming a profile with the determined profile contour with a shaping process on the peripheral surface of the tubular body. Independent claims are also included for the following: (A) a hollow profile (B) a drive system (C) and a vehicle with a drive system.

Description

The The present invention relates to a process for the preparation of Hollow profiles, in particular of hollow shafts in the automotive industry. The invention concerns about it In addition, a hollow profile or a drive system for a vehicle with a hollow profile, as well as a vehicle with a corresponding drive system. The Accordingly, the invention finds particular application in the automotive industry.

at the production of hollow profiles, such as hollow shafts for torque transmission, be special requirements for the life of such Set up components. The problem with hollow shafts have used hollow profiles in terms of in the production generated welded joints proved. Such welds run, for example, parallel to the longitudinal axis of the hollow shafts. she stand up regularly into a connection area. In the connection area are hollow shafts and especially drive shafts often equipped with gears, which form-fitting Connection of the hollow shafts provided on subsequent elements of drive trains are. these can be formed for example in the form of said gears. In the manufacture of the gears, however, it happens occasionally suggest that the areas of the weld joint a larger change in shape be subjected. this leads to to a vulnerability the hollow shafts in this area and reduces the life of the Component considerably.

The Forming of hollow sections is used in the automotive industry with different Procedure performed. Hollow profiles are regularly formed tubular and in the context of a subsequent transformation with a structure, such as a toothing provided. Here are the hollow profiles a change its outer diameter.

The Forming such hollow sections must regularly have special quality criteria suffice. This especially applies if the hollow shafts in use special static and dynamic forces or a high torque load are exposed. So on the one hand To avoid that during the formation of cracks in the material form. Consequently, the degree of deformation during such a forming process limited. On the other hand, there is still the desire to such motor vehicle components very easy to carry out, so here's the desire for thin-walled Hollow profiles is given. Especially in a process for forming of hollow profiles according to the so mentioned forward extrusion presses, However, occur in thin-walled Hollow profiles problems in the force application, while the Hollow profile with high degree of deformation through a corresponding die is passed. About that addition, Depending on the choice of material, sometimes complex forging processes during the Forming be made. Depending on the application, additional thermal or surface-specific Preparations of the hollow sections before the forming step or be made between a plurality of Teilumformschritten.

Of these, It is an object of the present invention to provide a method specify for the production of hollow profiles, which with reference at least partially described in the prior art to solve, wherein preferably a particularly durable compounds are created should. The method is further intended to provide a particular with regard to greater tolerance fluctuations lead to insensitive production, so that a hollow profile process reliable even with relatively large manufacturing tolerances and to produce with good results.

These Tasks are achieved by a method according to the features of the claim 1 and a hollow profile according to claim 8 solved. Further advantageous embodiments of the invention are formulated in each dependent claims specified. It should be noted that the individual in the claims listed Features in any, technologically meaningful way with each other can be combined and show further embodiments of the invention. The characteristics are further explained or specified in the description, so that here also advantageous developments of the invention shown become.

• a) Bereitstellen eines Rohrkörpers mit wenigstens einer Verbindung,
• b) Definieren einer imaginären Profilkontur mit wenigstens einer Gruppe von zusammenhängenden und in einer Umfangsrichtung des Rohrkörpers hinterschnittig ausgebildeten Abschnitten,
• c) Ermitteln einer Profilkontur mit Vorsehen wenigstens eines verbreiterten Abschnitts der Gruppe, so dass die Verbindung in einem Bereich des verbreiterten Abschnitts liegt, der ungekrümmt bleibt oder der mit einem Krümmungsradius ausgeführt wird, der mindestens das 0,5fache eines Radius des Hohlprofils ist,
• d) Ausbildung eines Profils mit der ermittelten Profilkontur mittels eines formgebenden Verfahrens an der Umfangsfläche des Rohrkörpers.

Accordingly, the method for producing a hollow profile, in particular of hollow shafts in the automotive industry, comprises at least the following steps:

• a) providing a tubular body with at least one connection,
• b) defining an imaginary profile contour with at least one group of contiguous and undercut sections in a circumferential direction of the tubular body,
• c) determining a profile contour with provision of at least one widened portion of the group so that the connection lies in a region of the widened portion which remains un-curved or which is executed with a radius of curvature which is at least 0.5 times a radius of the hollow profile,
• d) forming a profile with the determined profile contour by means of a shaping process on the peripheral surface of the tubular body.

In the inventive method for the production of hollow profiles, which in particular For the production of hollow shafts in automotive engineering, a tubular body is first provided, which has a longitudinal axis and a peripheral surface, wherein on the peripheral surface at least partially over the longitudinal axis of a (in particular cohesive) connection is provided.

Of the provided tubular body can be made with different cross sections, such as round, oval, edgy - however rotationally symmetric cross sections are preferred. As a material come in particular metallic materials in question, which a allow subsequent processing by means of a forming process. For this purpose, in the art a variety of steel alloys or also known other metal alloys.

• a.1) Formung zumindest eines Rohrkörpers unter Ausbildung wenigsten einer Stoßstelle und
• a.2) Schaffung einer Verbindung an einer Stoßstelle zur Erzeugung eines geschlossenen Rohrkörpers.

For the provision of such a tubular body, the following processes can be realized:

• a.1) forming at least one tubular body while forming at least one joint and
• a.2) Creating a connection at a joint to produce a closed tubular body.

Consequently In a first process, a tubular body can be made from a (flat) Material to be formed with the formation of at least one joint (bent). Later will be at this joint created a connection to produce a closed tubular body. A particularly simple and exemplary procedure for forming a tubular body consists of a sheet with a wall thickness of for example 4 mm, which as a flat Starting material serves to bend to a tubular body. Production can be done for example by means of a three-roll bending machine. In such a tube formed are two along two abutting edges of the newly formed tubular body across from, which, with sufficiently accurate production, is essentially blunt or along the longitudinal axis clash. The area with the two abutting edges is the so-called joint. The joint is then still to connect to produce a closed tubular body. This connection For example, by a technical joining (and in particular substance-coherent) Joining process, preferably by a weld, which essentially longitudinal or parallel to a longitudinal axis of the tubular body.

In a further step is an imaginary profile contour with at least a group of related and in the circumferential direction undercut sections Are defined. The reference to a "group of related ... sections "is to understand that the sections (particularly preferred) around the entire circumference of the tubular body can be provided but this is not mandatory. Accordingly, the at least one Group only about extend a partial extent. Advantageously, at most four Provided for groups. Undercut means that with parts of Sections formed in the direction of the circumference undercuts are. This can be z. B. in a section with a survey and a Valley can be achieved based on the direction of the circumference. there are the sections or elevations and / or sinks of a group the imaginary Profile contour preferably formed similar.

Then is the location of the connection with respect to the imaginary profile contour to identify an area of at least a section superimpose the group would. The identified at least one area of at least one section The group is to be widened so that the connection in one area of the Profile contour lies, the unbent should remain or its radius of curvature at least 0.5 times (preferably approximately the same or even at least twice) of an outer radius the hollow profile should not fall below. This modification of the imaginary profile contour is called determined profile contour. Then it is actually a Profile with the determined profile contour by means of a shaping process on the peripheral surface formed of the tubular body. The goal here is not an area of the tubular body and only small to deform during the production of the profile contour, which superimposed the compound Omit the area.

In order to the identified area after step d) preferably has substantially the same radius as the tubular body in step a).

widens the width of the section increases the distance of the connection to the respective lateral and particularly strong deformations subjected areas, such as the tooth flanks of the spline. The width of the section can in different ways be determined. With a spline with uniform pitch is it possible, the section with an integer one or more times a width To specify tooth pitch. The width can also be defined by a minimum distance of a cut-off from the connection is thereby defined as a measure of security against undesirable indicate strong deformation of the connection. For example, the measure a length specification be aware of the the section on both sides of the connection over this should protrude.

With the aid of the method according to the invention, it is thus possible to ensure that the connection is not subjected to excessive deformation during the subsequent generation of the profile contour. For example, the connection may lie in the region of a sufficiently wide tooth tip or tooth root Depending on how the respective section is formed. Only (at least) in the region of a tooth tip or tooth root does the profile contour have a radius of curvature that is sufficiently large. Such a region is, for example, a section of the outer or inner circumference of the tubular body which has a constant bending radius or a constant contour. The area is chosen to be wider in the direction of the circumference, the larger the detected on the circumference of the tubular body section. The larger the section formed straight or with a constant radius of curvature, the better the connection is protected against subsequent deformation by a subsequent forming process. The area of the section is preferably wider at least by a multiple of the connection (so that, for example, a heat-affected zone of the connection is spanned). In such an embodiment, then laterally adjoin to the widened portion or region thus formed zones which are subject to a particularly strong deformation during the subsequent forming process.

• – Bereitstellen eines Hohlkörpers mit einer Längsachse und einem Umfang, wobei sich wenigstens eine fügetechnische bzw. stoffschlüssige Verbindung zumindest über einen Teil der Langsachse erstreckt,
• – Einbringen einer Profilkontur mit wenigstens einer Gruppe von in Umfangsrichtung zusammenhängenden und Hinterschnitte bildenden Verformungsabschnitten, wobei wenigstens zwischen zwei Verformungsabschnitten eine (bereichsweise) Aussparung vorgesehen wird, die sich zumindest über den Teil der Längsachse erstreckt und die Verbindung überlagert.

In other words, the method for producing a hollow shaft with a hollow profile can also be illustrated with the following steps:

• Providing a hollow body with a longitudinal axis and a circumference, wherein at least one joining or material-locking connection extends over at least part of the longitudinal axis,
• - Introducing a profile contour with at least one group of circumferentially contiguous and undercuts forming deformation sections, wherein at least between two deformation sections a (regional) recess is provided which extends at least over the part of the longitudinal axis and superimposed on the connection.

To another advantageous embodiment The invention provides that the profile with the at least a section a centroid having on a longitudinal axis of the Hollow profile lies. "On a longitudinal axis "is intended to express bring that the centroid (geometric center of gravity of the cross-sectional area of the hollow profile) substantially Centric lies, so z. B. with a maximum deviation of at most 1 millimeter. Hollow profiles must in her later Installation position with very high speeds of, for example, 3,000 to Turn 8,000 revolutions per minute. It is desirable to that one as possible have low imbalance. For this purpose, the invention provides that the profile according to the invention with the determined profile contour has a centroid, the preferably exactly with a longitudinal axis of the hollow profile matches. In the case of the longitudinal axis, this is the axis of rotation of the hollow profile, around this in its later installation position rotates. This unbalance effect by uneven material distributions avoided. Thus, it is proposed in particular that the broadened Sections diametrically opposite executed the same are.

Basically Of course also possible, with the method proposed here an associated counterpart with a at least partially complementary to produce a shaped contour. This way, not just one Hollow shaft but also an associated connector be designed. This can be, for example, a socket which on its inner side to the profile contour of the hollow profile complementary trained surface having.

Especially good strength properties arise when the radius of curvature of the widened region extends through the longitudinal axis of the hollow profile. The Hollow profiles designed in this way can be used, for example, via a Mandrel made by hammering become. You will receive a particularly resistant material structure.

All it is particularly advantageous if the profile as a spline is formed, since such a toothing is particularly reliable and relatively inexpensive can be produced. For closer Explanations is here to the comments too the tooth heads, Tooth flanks and tooth feet referenced.

When furthermore particularly preferred method comes at least one from the group of the following: axial forming, feed hammering, hammering over one Mandrel, gear rolls. The axial forming means in particular a forming, in which the tubular body in the direction of the longitudinal axis is pressed or pulled by a profile forming die (where the template prefers over the circumference is provided with similar structures, the structures in the "widened Section "however are blocked - so do not reshape). When hammering is the tubular body over his (inner and / or outer) peripheral surface mechanically edited and pressed into a die (here also the die preferred over the Scope is carried out with similar structures, the structures in the "widened Section "but not to be used). These processes are easy to control on an industrial scale, relatively cheap and particularly easy to use in connection with the invention.

It is very particularly preferred that the region is formed the same on both sides of abutting edges of a joint. This is in particular ge means that the connection is centrically positioned with respect to the widened area.

a Another aspect of the invention is also a hollow profile with a longitudinal axis and a scope proposed, wherein at least one technical joining or cohesive Connection at least over extends a part of the longitudinal axis and a profile contour with at least one group of in the direction related to the scope and undercuts forming sections, at least between two sections a recess is provided which extends at least over the Part of the longitudinal axis extends and overlays the connection. This hollow profile leaves in particular produced with a method described herein according to the invention. Therefore, to the explanations there for description the hollow profile reference, being simultaneously noted is that these explanations sometimes without any connection with the method according to the invention can apply.

Especially Advantageously, it has proved, when the section a protected Range between 1 mm and 20 mm (especially 5 to 12 mm) on both sides the connection comprises, whereby a sufficient distance to the Areas with stronger Deformation (outside of the section) is.

preferred Way, the invention is used in hollow sections, which have a length between 300 mm and 2000 mm. These lengths can be especially for vehicles be used particularly advantageous.

at a further advantageous embodiment of the invention, the Hollow profile has a diameter between 30 and 150 mm, in particular between 40 and 100 mm. With hollow sections whose diameter in these areas lie, can be with common wall thickness transmit sufficiently high torques.

Cheap is if the hollow profile has a wall thickness between 1 and 7 mm, whereby an adaptation of the mass of the hollow profile to the respective Requirement case guaranteed is.

Of Furthermore, at this point, a drive system for a vehicle proposed which an inventive or inventively produced Hollow profile includes. Such a drive system can, for example have a hollow shaft and a complementarily shaped counterpart, both by the method according to the invention are formed. In this case, the widened section comprises the compound, so that this against excessive deformation protected is.

Finally will also a motor vehicle comprising a drive system according to one of mentioned above considered advantageous. With a like that designed vehicle is its performance, smoothness and, above all Durability through the use of a drive system according to the invention increased.

Further Advantages of the invention, as well as the technical environment are related with the following embodiments and the drawing. The illustrations in the figures however, should not limit the invention. It shows schematically in it:

1 a perspective view of a vehicle with different drive shafts;

2 a hollow shaft according to the invention in a front view and plan view;

3 : the detail III after 2 in an enlarged view; and

4 FIG. 2: another embodiment of a hollow shaft according to the invention in a radial sectional view. FIG.

In 1 shows an oblique view of a vehicle 1 with different drive shafts. The vehicle 1 is with a drive system 2 equipped, which has a plurality of hollow shafts 3 having. These serve primarily as a torque transformer from the engine to the rear wheels 4 , The hollow shaft 3 is in the middle of the vehicle 1 arranged and transmits the torque to the rear axle 5 , It is usually referred to as a propshaft or propeller shaft. Such longitudinal waves 6 can be constructed in one piece or in several parts. The dimensions depend on the respective space conditions of the respective vehicle 1 from. Basically, however, it should be noted that a longitudinal shaft 6 is exposed to high mechanical stress. The life of a longitudinal shaft 6 is usually to be interpreted throughout the life of the vehicle, which is why special attention must be paid to the durability of this component.

In 2 is a hollow shaft according to the invention 3 shown in a front view and a top view. In the lower part of the 2 is the hollow shaft 3 in plan view with its longitudinal axis 27 and the length 33 shown. It essentially has three segments in it. In the upper area there is a first segment 7 which has the smallest diameter. The first segment 7 For example, it is tapered so far that it is in another unillustrated component, which is connected to the hollow shaft 3 connects, can be inserted. Alternatively, the hollow shaft 3 also over a longer range with a smaller diameter 23 be trained to get along with as little space. Below the first segment 7 there is a second segment 8th which has a larger diameter 23 having. In the lower area there is a third segment 9 , which is formed according to the present invention. The third segment 9 is on the peripheral surface 35 with the inventively designed profile contour 10 fitted.

In the upper area of the 2 is a view on the upper front side 11 the hollow shaft 3 shown. There is clearly recognizable, as one through the profile contour 10 formed profile 12 over the entire circumference of the hollow shaft 3 is arranged. At the top is in profile 12 a connection 13 , which is designed as a weld. The in 2 The area marked III will be referred to 3 explained in more detail below.

In 3 is the figure range marked with III 2 reproduced again in an enlarged view. There is a single tooth 14 a profile 12 shown in an enlarged view, which serves together with a complementarily shaped counterpart for torque transmission. The tooth 14 has lateral flanks 15 on, as well as a profile 12 closing connection 13 , The connection 13 has the connection width 25 on. The opposite has the tooth 14 a tooth width 26 which is significantly larger than the connection width 25 the connection 13 is. The tooth width 26 indicates an area in which a tooth head 16 a constant and concentric radius with respect to a shaft center 17 or the long axis has. The area within the tooth width 26 of the tooth head 16 forms an area 18 the profile contour 10 who the connection 13 includes. The advantage of such an embodiment is that the connection 13 not in the area of the tooth flanks 15 which are subjected to severe deformation in the manufacturing process. The thus either not or only slightly deformed connection 13 has retained its original strength unlike a deformed one. As a result, the life and the load capacity of the hollow profiles produced increase considerably. In addition to the illustrated arrangement of the area 18 with the connection 13 in the area of a tooth head 16 Of course it is also possible to do the area 18 (alternatively) in a not in 3 To arrange shown tooth root. This would then apply the same, that is, the connection 13 with the connection width 25 would be from an area 18 with constant radius 28 and the tooth width 26 includes his. Only adjacent to this would a tooth flank 15 each to the right or left of it in the direction of a tooth head 16 increase.

In 4 another embodiment of an inventively designed hollow profile is shown. The hollow profile 3 Here, in turn, is designed as a hollow shaft. In the middle is the shaft center 17 which is on a shaft rotation axis 19 or longitudinal axis is shown. Moreover, this is also the area of focus 30 the profile 12 formed cross-sectional area on the shaft rotation axis 19 , The profile 12 has a profile contour 10 on that in the manner of a spline with sections 14 is formed, which in the direction of the circumference 24 seen undercuts 31 form. The profile contour 10 in turn consists of a large number of rows of teeth 14 (alternating bumps and valleys that extend circumferentially substantially radially inwardly and outwardly). The teeth 14 are each with tooth heads 16 trained and over tooth feet 20 connected with each other. All in the direction of a scope 24 connected, ie adjacent teeth 14 together form a group in the embodiment shown. In the upper area is a left edge 21 and a right-hand edge 22 shown via a welded joint connection 13 connected to each other. The connection 13 indicates the connection width 25 which in turn is much smaller than the tooth width 26 of the area 18 is. Except for the area 18 or the recess 32 has the profile shown 12 a uniform distributed over the circumference tooth pitch. In other words, the profile is thus constructed regularly, with (only) in the area 18 with the connection 13 (or possibly even lying opposite) at least two (tooth feet 14 or) tooth heads 16 directly merge into each other, so a continuous area 18 form. This extends the range 18 in the direction of the circumference 24 over a much greater distance (eg a multiple) than the (tooth root 14 or) tooth head 16 ,

In the illustrated embodiment was in the area 18 a whole tooth 14 directly with an adjacent tooth 14 with the omission of a tooth root 20 connected. The area 18 again has a constant radius 28 on, where the radius 28 concentric with the shaft axis of rotation 19 is aligned. The radius corresponds to this 28 in about the production of the tubular body 6 generated radius. This eliminates the need for a later introduction of the profile 12 a subsequent deformation, whereby the connection 13 essentially undeformed and thus the weld shown there is retained in its original strength. The pipe body 6 also has one over the circumference 24 seen essentially consistent wall thickness 34 ,

Furthermore, it should be noted that the present invention is not limited to the illustrated embodiments. There are many variations within the scope of the invention possible, which fall within the scope of the claims. For example, non-concentric constant radii may also be used instead of the concentrically arranged constant radii. Furthermore, it is also possible, in addition to the circumferential contouring of the outer circumference of the tubular body shown 6 this only in certain areas with a corresponding profile contour 10 and thus a profile 12 to provide.

1

vehicle

2

drive system

3

hollow profile

4

wheel

5

axis

6

pipe body

7

first segment

8th

second segment

9

third segment

10

profile Silhouette

11

front

12

profile

13

connection

14

tooth

15

flank

16

addendum

17

Shaft center

18

Area

19

Shaft axis of rotation

20

tooth root

21

left impact edge

22

right impact edge

23

diameter

24

scope

25

link width

26

tooth width

27

longitudinal axis

28

radius

29

joint

30

Centroid

31

undercut

32

recess

33

length

34

Wall thickness

35

peripheral surface

Claims (12)

Method for producing a hollow profile ( 3 ), in particular of hollow shafts in the automotive industry, which comprises at least the following steps: a) providing a tubular body ( 6 ) with at least one compound ( 13 ), b) Defining an imaginary profile contour ( 10 ) with at least one group of contiguous and undercut sections in a circumferential direction of the tubular body ( 14 ), c) determining a profile contour ( 10 ) with provision of at least one widened section ( 14 ) of the group so that the connection in one area ( 18 ) of the widened portion which remains uncurved or which is carried out with a radius of curvature at least 0.5 times a radius ( 28 ) of the hollow profile ( 3 ), d) training a profile ( 12 ) with the determined profile contour ( 10 ) by means of a shaping process on the peripheral surface ( 35 ) of the tubular body ( 6 ). Method according to claim 1, wherein step a) comprises the following at least processes: a.1) forming at least one tubular body ( 6 ) with the formation of at least one joint ( 29 ) and a.2) Creating a connection ( 13 ) at a joint ( 29 ) for producing a closed tubular body ( 6 ). Method according to one of the preceding claims, wherein the profile ( 12 ) with the at least one section ( 14 ) a centroid ( 30 ), which on a longitudinal axis ( 19 ) of the hollow profile ( 3 ) lies. Method according to one of the preceding claims, wherein the radius of curvature of the widened region ( 18 ) through the longitudinal axis ( 19 ) of the hollow profile ( 3 ) runs. Method according to one of the preceding claims, wherein the profile ( 12 ) is formed as a spline. Method according to one of the preceding claims, wherein as molding method at least one of the group of the following includes: axial forming, feed hammering, hammering over a mandrel, gear rolls. Method according to one of the preceding claims, wherein the area ( 18 ) on both sides of abutting edges ( 21 . 22 ) a joint ( 29 ) is formed the same. Hollow profile ( 3 ) with a longitudinal axis ( 27 ) and a scope ( 24 ), wherein at least one joining or material connection ( 13 ) at least over part of the longitudinal axis ( 27 ) and a profile contour ( 10 ) with at least one group in the direction of the circumference ( 24 ) and undercuts ( 31 ) forming sections ( 14 ), whereby at least between two sections ( 14 ) a recess ( 32 ) is provided, which extends at least over the part of the longitudinal axis ( 27 ) and the compound ( 13 ) superimposed. Hollow profile ( 3 ) according to claim 8, wherein the section ( 14 ) an area ( 18 ) between 1 mm and 20 mm on both sides of the connection ( 13 ). Hollow profile ( 3 ) according to claim 8 or 9, wherein at least one of the following parameters is fulfilled: - a length ( 33 ) between 300 mm and 2000 mm, - a diameter ( 23 ) between 30 mm and 150 mm, in particular between 40 mm and 100 mm, - one wall thickness ( 34 ) between 1 mm and 7 mm. Drive system ( 2 ) for a vehicle ( 1 ), comprising a hollow profile ( 3 ) produced according to one of claims 1 to 7 or according to one of claims claim 8 to 10. Vehicle ( 1 ) comprising a drive system ( 2 ) according to claim 11.