DE102006018809A1 - Method for producing a motor vehicle pivot bearing in shell construction - Google Patents

Abstract

The invention relates to a method for producing a motor vehicle swivel bearing (12) in a shell design, wherein at least one half-shell (9) of the swivel bearing (12) is made from a sheet metal blank (5) by deep-drawing in a forming tool (1) with a molding space (8 ) will be produced. In order to enable a simplified production of a pivot bearing with improved properties, it is provided that in a first step the sheet metal blank (5) is heated and that in a second step the sheet metal blank (5) is inserted into the die (2) and male mold (3) existing forming tool (1) is inserted and the forming tool (1) is closed with pressure.

Description

Territory of invention

The The invention relates to a method for producing a motor vehicle pivot bearing in Shell construction, wherein at least one half shell of the pivot bearing from a sheet metal blank by deep-drawing forming in a forming tool is made with a mold cavity.

background the invention

pivot bearing for the Front axle of a motor vehicle, which are also referred to as wheel carriers, make the connection between a damper or strut, the wheel bearing and the control arm on the front axle of a motor vehicle ago. The coupling of the wishbone with the pivot bearing takes place over it a formed on the pivot bearing guide joint receptacle.

at usual Swing bearings are mostly cast or forged, one-piece steel parts, for example, from a cast steel material or aluminum casting material getting produced. So this is a massive component, in which all functional surfaces must be reworked. The damper strut is usually by means of a screw or clamp connection with the pivot bearing connected.

From the DE 199 15 633 A1 is a pivot bearing for the front axle of a front-wheel drive motor vehicle with a main body made of mutually connectable sheet metal parts known, being attached to the sheet metal parts components for the suspension and the wheel guide and for the braking of the wheel. Both the sheet metal parts and other components of the pivot bearing are made of a titanium alloy material. As a manufacturing method is described there that the basic body forming sheet metal parts are produced by a deep drawing process, so that they are present as two complementary shaped sheet metal parts, which together via a welded joint together form a hollow body with a plurality of bonding surfaces for receiving the components described above.

Further details of the manufacture of the pivot bearing are in the DE 199 15 633 A1 not specified. The pivot bearing described therein offers a number of advantages over one-piece, massive pivot bearings or wheel carriers. In particular, such a pivot bearing by the use of thermoforming sheets on a low weight. However, the material used, namely a titanium-aluminum alloy, for example, TiAl6V4, very expensive, so that the advantages of a lightweight construction, the disadvantages of high material costs preclude.

Moreover, from the DE 101 62 441 A1 is a method for producing motor vehicle components, in particular chassis parts, body parts, drive parts, engine parts or the like, of metallic materials, in particular aluminum or aluminum alloys, known, in which by means of an active media-assisted high-pressure hot forming in a forming tool with a mold space from an initial form an intermediate or final shape is generated. In order to control the material flow, the mold space region is tempered by heat supply and / or heat removal in the course of softening processes and solidification processes, wherein a forming tool with a partially heated or cooled mold space is used. The hot forming takes place by means of a hydroforming at temperatures between 150 ° C and 450 ° C. As a result, one-piece motor vehicle components should be particularly easy and inexpensive to produce.

That from the DE 101 62 441 A1 Known methods may be advantageous in a number of automotive components made of aluminum materials, but it is not necessarily transferable to the manufacture of automotive pivot bearings. Because the geometry of serving as a wheel pivot bearing in shell construction can not be chosen arbitrarily due to the spatial boundary conditions, in particular clearance, acting forces of propeller shaft, brake, rim, tie rod, stabilizer or wishbone. The forces acting on the pivot bearing during operation give rise to typical critical areas in which excessive stresses occur, which can lead to premature fatigue cracks and fatigue fractures on the pivot bearing.

A possibility The stress reduction at these points could be a targeted material thickening be, for example, by pre-processing of the sheet metal plate by Rolling, a doubling or the use of so-called Tailored Blanks. However, that would this to an increased Manufacturing costs or lead to an increased use of materials, the undo the advantages of a pivot bearing in shell construction would.

Task of invention

The invention has for its object to provide a method for producing a motor vehicle pivot bearing in shell construction, with which a pivot bearing can be easily and inexpensively produced, which at the points high force transmission is designed to be particularly resistant.

Summary the invention

Of the Invention is based on the finding that the asked Task on surprisingly simple Solve it by way of fashion leaves, that the production of at least one half-shell of the pivot bearing by hot forming in a matrix and male part Forming tool is carried out, wherein at least a portion of the deformed Sheet metal by cooling hardened becomes.

The Invention is therefore based on a method for producing a Motor vehicle pivot bearing or wheel carrier in shell construction, wherein at least a half-shell of the pivot bearing from a sheet metal blank by deep-drawing forming is produced in a forming tool with a mold cavity.

furthermore is provided that heats the sheet metal blank in a first step, for example to a temperature above room temperature, that will be in one second step the metal sheet into the die and male existing forming tool inserted and closed the forming tool with pressure becomes.

In In a third step, at least one area of the sheet can pass through Cooling, i.e. active or passive cooling, hardened become. Here, the active cooling by means of a, in particular through the forming tool or through a part or parts led the forming tool, coolant can be effected. The passive cooling can by a heat absorption the forming tool or a part or parts of the forming tool be effected.

By This structure is advantageously achieved that the sheet through previous warming to a relatively high temperature quickly and easily in the forming tool in the desired Form can be reshaped, and that during targeted cooling, in particular selective or selected and / or discrete or separate areas of the sheet, preferably a sheet of one Steel alloy, achieve a so-called press hardening of these areas leaves.

alternative and / or in addition for selective cooling in the tool, the sheet can also be selectively heated before forming, i.e. through appropriate measures areas of the sheet are heated to different temperatures and subsequently cooled selectively or homogeneously during forming.

generally known sets the steel structure from chemically homogeneous areas, the phases, together. When heating in a high temperature range of about 700 ° C to 1000 ° C, the Ausgangsgefüge completely transformed into Austenite around. Preference is given to heating to a temperature above 450 ° C, especially preferably at a temperature in the range from 700 ° C to 990 ° C, preferably on a temperature around 800 ° C.

a significant influence on the material properties caused now the subsequent cooling of the desired Areas while of which the austenite phase is in the four different phases Convert ferrite, perlite, bainite and martensite. The perlite phase, for example has a low hardness and big Moldability, the martensite, however, a great external hardness, but also a certain Brittleness.

The press hardening of the first Austenitic sheet thus causes the desired setting hardening of the pivot bearing produced by the method. So there the Material strength after forming next to the material composition the sheet of parameters such as the cooling rate and the positive connection depends, and these parameters locally can be varied, according to the method, a targeted distribution of strength in the workpiece be generated, which in connection with the component geometry the Takes into account stresses during operation of a later component.

By leave the process according to the invention more surprising Benefits. For example, a mass reduction achievable by optimizing the sheet thickness. Furthermore, on otherwise necessary Preliminary work, such as the thickening by means of rolling or welding of different sheet thicknesses of the sheet are dispensed with.

It It was also found that the process results in a more uniform material stress and thus lower local Thinning at Forming takes place as the glowing Sheet metal material is much easier to shape. Hereby leave lower press forces as usual deploy.

To the reshaping and complete cooling down a half shell is expected to be only negligible slight springback of the Determine components, resulting in a higher achievable precision of Components of the pivot bearing results.

If required, moreover, a flexible design of the distribution of strength during production can be achieved, for example by selectively changing the forming parameters, in particular the temperatures and the pressures in the mold.

Besides, has proved to be an advantage of the method that less residual stress be introduced into the component, which is not only positive when welding but also during the load of the finished pivot bearing in operation. So far was in fact the danger of being in the unfavorable Fall the strength of the material for the most part by such residual stresses is used up.

furthermore can be provided that a coolant in the forming tool for selective hardening of the hardened Areas is fed.

In other practical developments it can be provided that the areas with a resulting tensile strength R _mmax of 600 to 1400 MPa are cured. The tensile strength R _mmax of 1400 MPa corresponds to an elongation at break of about 5%, and the tensile strength R _mmax of 600 MPa corresponds to an elongation at break of about 20%.

Other practical embodiments of the invention are characterized by that the sheet metal blank before inserting into the forming tool with a a surface scaling preventing coating is provided, this coating according to a Continuing education on aluminum-silicon or based on graphite.

Further can according to another Configurations be provided that at least two inventively prepared Half shells connected together to form the pivot bearing or wheel carrier be, with this configuration can be further expanded by that the half-shells are welded together.

A further practical embodiment of the method according to the invention provides that the pivot bearing a receptacle for a damper tube is formed, wherein the inclusion by corresponding one-piece formations is formed on the half-shells. Finally, a particularly advantageous is Embodiment of the invention, which is characterized in that as material for the sheet metal plate is a steel alloy used.

Short description the drawings

The The invention will be explained in more detail below with reference to the accompanying drawings. In this shows

1a to 1d Process steps of a method according to the invention, and

2 a according to the method according to the 1a to 1d manufactured swivel bearing.

detailed Description of the drawings

In the 1a to 1d Accordingly, the sequence of a manufacturing method according to the invention is shown schematically.

In 1a is a forming tool 1 shown in cross section, which consists of a die 2 and a patrix 3 or an embossing stamp exists.

In a gap 4 between downholder and die 2 is a metal sheet 5 made of sheet steel, which was heated to a temperature of ≥ 800 ° C before insertion. The sheet metal plate 5 forms after completion of the process, a half shell of a motor vehicle pivot bearing or wheel carrier.

Between top 6 the patrix 3 and the inside 7 the matrix 2 between which the sheet metal blank 5 is arranged, is a form space 8th educated. Before the sheet metal blank 5 heated and in the forming tool 1 is inserted, was the sheet metal blank 5 provided with a coating which prevents surface Verzunderung. Such a coating may be based on aluminum-silicon or graphite.

In 1b a manufacturing state is shown, in which the forming tool 1 by moving matrix together 2 and male 3 closed is. The still glowing hot metal sheet 5 has conformed to the topographies of template 2 and male 3 to a half shell 9 deforms and fills the mold space 8th completely off. Because of the metal sheet 5 heated to a relatively high temperature is the steel material of the sheet metal blank 5 relatively soft, allowing for closing the forming tool 1 a lower force must be used than in a cold forming process.

In 1c is the condition of 1b shown in more detail, wherein in dotted marked areas 10 and 11 , Which represent areas of high loads of the later pivot bearing, a cooling of the sheet metal half-shell 9 takes place, thereby curing the sheet in these areas 10 and 11 to reach.

For this purpose, via lines, not shown, a cooling medium in the forming tool 1 fed, reducing the temperature of the half shell 9 is lowered to a value which is lower than the temperature of the remaining half-shell 9 , After the (cooled) press hardening of the areas 10 and 11 becomes the half shell 9 formed and from the forming tool 1 away.

A cross section through the finished and abge cooled half shell 9 is in 1d shown. Again, the now hardened areas 10 . 11 shown dotted. The hardness of these areas 10 and 11 is greater than the hardness of the remaining half shell 9 ,

In a subsequent, not shown step, the half shell 9 welded with a second half-shell to a finished pivot bearing or wheel, where appropriate, other components can be welded or screwed to the pivot bearing.

In 2 is a finished pivot bearing 12 shown. This consists of two half-shells welded together, with in 2 only the half shell 9 can be seen while the other half-shell the back of the pivot bearing 12 forms. The pivot bearing 12 has a steering lever as usual 13 , two tabs for brake connection 14 and 15 , a wheel bearing mount 16 as well as a recording 17 for a damper tube of a shock absorber. The recording 17 is here in one piece to the pivot bearing 12 formed, wherein the forming process in the forming tool 1 took place. In the field of recording 17 Both shells were provided with a corresponding trough, which put together the recording 17 form.

As in the 1c and 1d indicate dotted areas 10 . 11 . 18 and 19 also in 2 those areas which have been cured during the manufacturing process according to the invention by selective cooling. These areas 10 . 11 . 18 and 19 represent those areas where otherwise particularly high mechanical stresses prevail. Outside of these areas 10 . 11 . 18 and 19 the material hardness is lower in favor of a higher material toughness.

1

forming tool

2

die

3

punch

4

gap 4 between downholder and die 2

5

sheet metal blank

6

Top of the patrix 5

7

Inside of the die 2

8th

cavity

9

half shell

10

Area hardening

11

Area hardening

12

pivot bearing

13

steering lever

14

Bremszarge

15

Bremszarge

16

Wheel recording

17

admission a damper tube

18

Area hardening

19

Area hardening

Claims (13)

Method for producing a motor vehicle pivot bearing ( 12 ) in shell construction, wherein at least one half-shell ( 9 ) of the pivot bearing ( 12 ) from a sheet metal blank ( 5 ) by thermoforming in a forming tool ( 1 ) with a molding space ( 8th ), characterized in that - in a first step, the sheet metal blank ( 5 ) is heated, in particular to a temperature above room temperature, - that in a second step, the sheet metal blank ( 5 ) into the die ( 2 ) and patrix ( 3 ) existing forming tool ( 1 ) and the forming tool ( 1 ) is closed with pressure. Method according to at least one of the preceding claims, characterized characterized in that in a third step at least one area of the sheet by cooling hardened becomes. Method according to at least one of the preceding claims, characterized characterized in that in a third step selective or selected and / or discrete or separate areas of the sheet are cured by cooling. Method according to at least one of the preceding claims, characterized in that a coolant into the forming tool ( 1 ) for curing at least one area to be cured ( 10 . 11 . 18 . 19 ) of the sheet is fed. Method according to at least one of the preceding claims, characterized characterized in that to a temperature above 450 ° C, in particular to a temperature from a range of 700 ° C to 990 ° C, preferably to a temperature around 800 ° C, heated becomes. Method according to at least one of the preceding claims, characterized in that areas of the sheet metal blank ( 5 ) are selectively heated before forming. Method according to at least one of the preceding claims, characterized in that the regions ( 10 . 11 . 18 . 19 ) with a resultant tensile strength R _mmax of 600 to 1400 MPa. Method according to at least one of the preceding claims, characterized in that the sheet metal blank ( 5 ) before being placed in the forming tool ( 1 ) is provided with a Oberflächenverzunderung preventing coating. Method according to claim 8, characterized in that that the coating is based on aluminum-silicon or graphite. Method according to at least one of the preceding claims, characterized in that at least two half shells ( 9 ) with each other to form the pivot bearing ( 12 ) get connected. Method according to at least one of the preceding claims, characterized in that the half shells ( 9 ) are welded together. Method according to at least one of the preceding claims, characterized in that to the pivot bearing ( 12 ) a recording ( 17 ) is formed for a damper tube, wherein the receptacle ( 17 ) by corresponding one-piece formations on the half-shells ( 9 ) is formed. Method according to at least one of the preceding claims, characterized in that as material for the sheet metal blank ( 5 ) a steel alloy is used.