EP1252947A2 - Method for the manufacture of an axle element for a motor vehicle - Google Patents

Abstract

A bar-shaped semi-finished part (1) of aluminum is heated to forming temperature, its first end (2) is upset in a mold (4) of a forming tool (3) by a first die (5), and the second end (9) is pressed into the mold by a second die (8). Displaced material is forced into a bypass (10) of the mold and formed into a leg (11). The semi-finished part is finished in a forging process. The forging temperature is lower than 520 degrees C, e.g. between 420 degrees C and 480 degrees C. Forging temperature is approx. 520 degrees C.

Description

The invention relates to a method for producing an axle element for Motor vehicles.

Axle elements of motor vehicles, in particular swivel bearings for the front axle, are relatively complex cast or forged one-piece designs Components made of cast steel or aluminum getting produced. Considerable forces act on pivot bearings, which is why these components are usually made from a solid material. For reasons the weight savings come increasingly light metals, such as aluminum, for use.

In the forging production of swivel bearings made of aluminum extruded round material serves as a blank. Fully forged However, swivel bearings have a very uneven mass distribution, which does not go along with the cylindrical shape of the blank. To still in Areas where there must be more mass than in other areas to have enough material available for the forging process, sufficiently large blanks are used. The disadvantage of the used Blanks is that a relatively large amount of energy is required to power the Heat the blank to the forging temperature required for hot forming. On the other hand, the proportion of waste is in areas with lower mass accumulations quite high. This is particularly disadvantageous in terms of cost because of it aluminum is a comparatively expensive material. The The above problems apply not only to swivel bearings, but to axle elements in general.

Proceeding from this, the object of the invention is to develop a method for Production of an axle element for motor vehicles from a rod-shaped To show semi-finished aluminum, in which the to be fed for forming The amount of energy is reduced and production-related material losses be reduced.

The solution according to the invention lies in a method for producing a Axle elements for motor vehicles, in which a rod-shaped semi-finished product Aluminum heated to a forming temperature and the first end of the semi-finished product in an engraving of a forming tool upset by a first stamp , then the second end of a second stamp in the engraving is pressed, with the pressed material in a branch of the Engraving is formed into a leg. This then includes itself Forging process in which that has already been formed into a pre-forging Semi-finished product is finished.

With the invention it is achieved that the uniform mass distribution of the rod-shaped semifinished product, in particular a round material, with regard to the axis element to be manufactured is changed so that in areas with larger mass accumulations in a preliminary stage of the actual forging process more material is provided than in other areas and thus achieving a mass distribution similar to that of the axis element to be manufactured becomes.

For the upsetting, the forming tool is engraved with a material thickening in discrete areas. Depending on the engraving the first end immediately upset by the stamp. It can but also a recess of the engraving at a distance from the first end of the Semi-finished product can be provided, in which a material accumulation during the upsetting process resulting from pressed material. The geometric shape of the engraving is taking into account certain diameter / compression length ratios established. To wrinkles on the surface too should avoid the upsetting length five times the diameter of the semi-finished product do not exceed. The first stamp on the semi-finished product is used for upsetting approached and then moves at a speed of up to 150 mm / s to the specified upsetting length.

Following the emergence of the first end, a second stamp is effective on the second end of the semi-finished product and press it into the engraving. The pressed material flows backwards into a branch of the engraving, the is at an angle to the central longitudinal axis of the rod-shaped semi-finished product. Here will the pressed material is shaped into a leg. The junction can be formed at half the compression length. The engraving is advantageous designed that a neutral fiber in the area of the central longitudinal plane of the molded Leg is formed. This ensures that in the subsequent Finish forging in the die this neutral fiber into the ridge flows and thereby enables a flawlessly directed microstructure in the component becomes. The neutral fiber is determined by the parameters Temperature of the forming tool and the semi-finished product, geometry of the Engraving and friction on the surface of the engraving in their recrystallization behavior affected. The optimal choice of these parameters is recrystallization reducible to a minimum.

With this invention, two different are in a single forming tool Process combined. On the one hand, end upsetting of the semi-finished product and on the other hand an extrusion for training of a leg without the rod-shaped semi-finished product between these two Manufacturing steps are fed to another forming tool would.

The semi-finished product thus formed into a pre-forging is then finished in a forging process.

The advantages of the process can be seen in the fact that semi-finished products, such as extruded round material with a smaller initial cross-section can be used and still a cheap forging Mass distribution is achieved through the preforming. At the same time is for heating of the semi-finished product energy due to the lower mass of the Semi-finished lower. Finally, the contours are close to the final shape of the pre-forging, less burr losses during the forging process, see above that less raw material has to be used from the outset.

From a plant engineering point of view, the sensible division of forces for Upsetting and backward extrusion are necessary, these operations advantageously be carried out in the horizontal direction. To the forming tool To keep it closed during the forming process, the locking force acting on the forming tool is approximately ten times that of the force applied to the first stamp and the second stamp.

According to the measures of claim 2, the second end of the semi-finished product pressed into the engraving against the holding force of the first stamp. The means that after the first stamp has been puffed up, it is marked as Counterholder functions and without loss of time or implementation of the workpiece Extrusion process can be initiated by the second stamp. Vice versa the second stamp also serves as a counterhold during the upsetting process.

While raw parts during hot forging to a temperature above the Recrystallization temperature to be heated, so that no permanent solidification workpiece material occurs, it is sufficient for the production of a pre-forging made of aluminum that the forming temperature is lower than 520 ° C (claim 3). Rather, a forming temperature between 420 ° C and 480 ° C for forming the semi-finished product are sufficient (claim 4). A Forming at too low a temperature can result in a non-degraded dislocation density cause the subsequent heating to the Forging temperature to an uncontrolled and undesirable coarse grain formation through recrystallization processes.

According to claim 5, the first end of the preformed semifinished product before Forging process compressed again in a second forming tool. This can be particularly advantageous if the first Stamp applied forces to emerge a certain amount allowed to exceed, so that material does not enter the junction of the Engraving flows, but only through the extrusion process through the second Stamp is placed in the branch in a controlled manner. A second forming tool thus enables the pre-forging to be contoured even closer to the final shape.

To prevent permanent hardening of the workpiece material provided according to claim 6, the pre-forging before the forging process to heat to a forging temperature that is convenient above the recrystallization temperature is heated. About 520 ° C is appropriate here (Claim 7).

The method described above is suitable for the production differently configured axis elements, but especially for manufacturing of pivot bearings (claim 8).

Figur 1

ein stabförmiges Halbzeug aus Aluminium;

Figur 2

das Halbzeug aus Figur 1 mit einem aufgestauchten ersten Ende;

Figur 3

das zu einem Vorschmiedestück umgeformte Halbzeug gemäß Figur 2 mit einem angeformten Schenkel an seinem anderen Ende;

Figur 4

ein aus dem Vorschmiedestück gemäß Figur 3 endgeformtes Schwenklager;

Figur 5

im Schnitt eine Vorrichtung zur Durchführung des Verfahrens, wobei in einem ersten Verfahrensschritt das erste Ende des Halbzeugs aufgestaucht wird, und

Figur 6

die Vorrichtung gemäß Figur 5, wobei der Schenkel ausgeformt wird.

The invention is explained in more detail below with reference to an embodiment shown in schematic drawings. Show it:

Figure 1

a rod-shaped semi-finished product made of aluminum;

Figure 2

the semifinished product from Figure 1 with an upset first end;

Figure 3

the semifinished product formed into a pre-forging according to FIG. 2 with an integrally formed leg at its other end;

Figure 4

a swivel bearing finally formed from the pre-forging according to FIG. 3;

Figure 5

in section a device for performing the method, the first end of the semifinished product being swaged up in a first method step, and

Figure 6

the device according to Figure 5, wherein the leg is formed.

Figure 1 shows a rod-shaped semifinished product 1 made of aluminum, specifically an extruded one Round material. This semi-finished product 1 is shown in a not shown Production step heated to a temperature of 450 ° C and then reshaped in two steps.

The first manufacturing step is an upsetting of the first end 2 of the semi-finished product 1 to a diameter D2, which is compared to the diameter D1 of the Semi-finished product 1 is approximately twice as large. The remaining un-compressed Length L2 of the semi-finished product 1 is slightly more than half the initial length L1 of the semi-finished product 1.

The upsetting of the semi-finished product 1 takes place in a forming tool 3 according to Figure 5. For this purpose, the semi-finished product 1 is engraved 4 in the forming tool 3 inserted and enclosed by the forming tool 3. A first stamp 5 acts on the first end 2 of the semi-finished product 1 and compresses it accordingly the contouring of the engraving 4 of the forming tool 3. The first End 2 undergoes a deformation into a cylindrical end section 6 with the Diameter D2 (see FIG. 2), which has a conical intermediate section 7 the diameter D1 of the semi-finished product 1 is tapered.

So that the semifinished product 1 is securely in the forming tool 3 when upsetting is held, another stamp 8 brings a counterforce to the second End 9 of the semi-finished product 1.

After emergence, the first stamp 5 serves as a counterhold, during the second stamp 8 presses the second end 9 of the semi-finished product 1 into the engraving 4. Here, the compressed material of a branch 10 open at the end Engraving 4 supplied, with a leg 11 at the second end 9 of the semifinished product 1st is formed as it is made on the semi-finished 1 Pre-forging 12 according to Figure 3 can be seen. The leg 11 is corresponding the contour of the branch 10 is formed so that the Extrusion results in a favorable fiber orientation in the pre-forging, that is, that the branch 10 or the leg 11 in the transition to the semi-finished product 1 receiving longitudinal engraving is provided with radii, so that a smooth transition results.

In a further process step, not shown in more detail, this becomes the Pre-forging 12 formed semifinished product 1 from the forming tool 3 removed and heated to a forging temperature of about 520 ° C. Subsequently the forging 12 shown in Figure 3 to that in Figure 4 swivel bearing shown forged.

REFERENCE NUMBERS

1 -

Workpiece

2 -

first end of 1

3 -

forming tool

4 -

Engraving in 3rd

5 -

first stamp

6 -

cylindrical end portion v. 2

7 -

conical intermediate section v. 2

8th -

second stamp

9 -

second end v. 1

10 -

Junction v. 4

11 -

leg

12 -

Vorschmiedestück

13 -

pivot bearing

L1 -

Length of 1

L2 -

Length of 2

D1 -

Diameter of 1

D2 -

Diameter of 2, 6

Claims (8)

Method for producing an axle element for motor vehicles, in which a rod-shaped semi-finished product (1) made of aluminum to a forming temperature heated and the first end (2) of the semi-finished product (1) in an engraving (4) a forming tool (3) from a first stamp (5) , then the second end (9) of a second stamp (8) in the engraving (4) is pressed, with pressed material in a branch (10) the engraving (4) is formed into a leg (11) and then the semi-finished product (1) formed into a pre-forging (12) in one Forging process is finally formed. Method according to claim 1, characterized in that the second end (9) of the semi-finished product (1) is pressed into the engraving (4) against the holding force of the first stamp (5). A method according to claim 1 or 2, characterized in that the forming temperature is lower than 520 ° C. Method according to one of claims 1 to 3, characterized in that the forming temperature is between 420 ° C and 480 ° C. Method according to one of claims 1 to 4, characterized in that the first end (2) of the preformed semifinished product (1) is compressed again in a second forming tool before the forging process. Method according to one of claims 1 to 5, characterized in that the pre-forging (12) is heated to a forging temperature before the forging process. A method according to claim 6, characterized in that the forging temperature is about 520 ° C. Method according to one of claims 1 to 7, characterized in that the axle element is a pivot bearing (13).

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