DE102010009729A1 - Method for manufacturing brake disk for disk brake of motor vehicle i.e. passenger car, involves machining disk pot before adding by loops or precision turnings, and smooth rolling front surface i.e. abutment surface, of pot for wheel hub - Google Patents

Abstract

The method involves adding a brake disk pot (14) from a thin walled metal sheet with a friction ring from cast alloy i.e. grey cast iron. The brake disk pot is machined before adding by loops or precision turnings. A front surface (16) i.e. abutment surface, of the brake disk pot is smooth-rolled for a wheel hub. A steel- or hard metal roller (32) is used for smooth rolling. The smooth rolling is prolonged until a rough depth of the front surface amounts to less than 1 micrometer. Surface roughness of the front surface is halved during smooth rolling.

Description

The invention relates to a method for producing a brake disk for a disk brake of a motor vehicle according to the preamble of patent claim 1.

In the course of modern lightweight construction efforts in the automotive industry increasingly composite brake discs for disc brakes are used, which consist of a brake disc hub and a separately manufactured friction ring. The brake disk hub is preferably made of thin-walled sheet metal, in particular aluminum sheets, while for the friction ring tribologically favorable materials, such as gray cast iron are used, which have a good thermal conductivity to derive friction heat generated during operation of the brake disk can.

The brake disk pots for such brake disks are often processed by defined or undefined tensioning methods, such as fine turning or grinding. This results in roughness peaks on the surfaces of the brake disk hub. In its final assembly such a disc is bolted to the brake disc pot with a wheel with a motor vehicle, wherein a partial surface of the brake disc hub rests against the wheel. There is a risk of contact corrosion and tribocorrosion in this area. Especially the roughness peaks caused by the machining affect the corrosion and wear resistance of the brake disc in the contact area of the brake disc hub to the wheel. Due to the uneven heights of roughness peaks, the material bearing component of the contact surface is also reduced, which further reduces the durability. Overall, therefore, there is a great risk of permanent friction fractures, which reduces the life of such brake discs.

In order to improve the durability of composite brake disks under the static and dynamic loads of the driving operation, it is known to coat the joining surface of aluminum brake disk pots with harder materials and / or hard anodize aluminum brake disk pots. The known methods are complicated to carry out and increase the manufacturing cost of such brake discs considerably.

The present invention is therefore based on the object to further develop a method for producing a brake disc according to the preamble of claim 1, that in a simple way particularly wear-resistant and corrosion-resistant brake discs are obtained.

This object is achieved by a method having the features of patent claim 1.

In such a method for producing a brake disc for a disc brake for a motor vehicle, in particular a passenger car, a brake disc hub is made of a thin-walled sheet metal with a friction ring of a casting alloy, in particular made of gray cast iron. Before joining, the brake disk pot is in particular machined by grinding or fine turning. According to the invention, it is provided that, after the preliminary machining, a surface of the brake-disk cup, in particular a contact surface of the brake-disk cup, is smoothly rolled for a wheel nose.

During burnishing, carbide or steel rollers are guided under contact pressure over the surface of the brake disk hub to be machined, thereby displacing microscopic surface peaks of the surface surface layer. The displaced volume of material flows from below into the profile valleys of the surface between the surface tips. This plateau form on the surface, so that the supporting portion of the surface is increased. In addition, residual compressive stresses are introduced into a surface area close to the brake disk chamber so that the strength and the hardness of the brake disk chamber are increased in the joining region between the brake disk chamber and the wheel. This further increases the fatigue strength of the connection between the brake disk chamber and the wheel.

Due to the increased carrying portion of the surface, the maximum transmittable torque between a wheel and the brake disc cup is simultaneously increased. The reduction in the roughness peaks simultaneously reduces the tribocorrosion during continuous operation of the brake disc. Due to the increase in the static yield strength of the material achieved by cold working during smooth rolling, there is also a proportional increase in the alternating strength of the brake disk cup.

The smooth-rolling is preferably carried out until a roughness depth of the machined surface is less than micrometers. This provides a particularly large load-bearing surface and almost completely eliminates the possibly abrasive top surface tips. This results in a particularly good durability and durability of the brake disc.

It is also advantageous to roughly halve the surface roughness of the surface during burnishing. When machining premachining, therefore, attention must also be paid to the extent of the introduced roughness peaks, so that the desired final roughness is achieved in conjunction with the smooth rolling.

Preferably, a burnishing tool made of several rolls is used for smooth-rolling in order to achieve a particularly good production speed and surface quality.

In the following, the invention and its embodiments will be explained in more detail with reference to the drawing. Show here.

1 a schematic representation of the change of a surface during the burnishing;

2 a sectional view through the surface according to 1 ; and

3 an embodiment of a two-piece brake disc.

One in total with 10 designated brake disc includes a friction ring 12 and a brake disk pot 14 , The brake disk pot 14 includes an end face 16 with screw holes 18 and a central passage opening 20 , The face 16 lies in the mounting state of the brake disc 10 on a wheel hub, the brake disc 10 over the screw holes 18 the wheel hub is bolted. The brake disk pot 14 consists of thin-walled aluminum sheet during the weight saving, while the friction ring 12 is made of the tribologically cheaper gray cast iron.

In the example shown, the friction ring 12 designed in two parts and includes two friction ring halves 22 . 24 that have spacers 26 , which are not all designated for clarity, are interconnected. Between the spacers 26 extend radial ventilation ducts 28 for cooling the brake disc 10 , which are also not all designated.

The surface 16 of the brake disk pot 14 is usually machined by fine turning or grinding. The surface 16 therefore has as in 1 and 2 shown, roughness peaks 30 on. The roughness peaks 30 reduce the carrying amount of the surface 16 in the assembled state of the brake disc 10 , At the same time it may be due to the roughness peaks 30 to Tribocorrosion between brake disc pot 14 and hub come.

To the mechanical properties of the surface 16 of the brake disk pot 14 to improve, the surface becomes 16 smoothed after machining. For this purpose, a roller burnishing 32 in the direction of the surface normal to the surface 16 of the brake disk pot 14 Pressed and rotating along the surface 16 emotional. Due to the contact pressure of the roller burnishing roller 32 the material of the roughness peaks flows 30 in the intervening valleys 34 so that after rolling a smoother surface area 36 results in much lower roughness.

As a result, the supporting portion of the surface is increased, so that tribo-corrosion is reduced during operation of the brake disc. At the same time is due to the contact pressure of the roller burnishing 32 the surface 16 compressed and compressive residual stresses in the material of the brake disc hub 14 brought in. The resulting hardening further reduces corrosion in the operation of the brake disc. The surface roughness after burnishing is preferably one micron or less.

Overall, thus, a surface 16 created of particularly high quality, without the costly measures such as coating or anodizing necessary. In this way worked brake discs 10 have a particularly good resistance to load changes and a long service life.

LIST OF REFERENCE NUMBERS

10

brake disc

12

friction ring

14

brake disc pot

16

face

18

screw opening

20

Through opening

22

Reibringhälfte

24

Reibringhälfte

26

spacer

28

ventilation duct

30

asperities

32

rolling roller

34

Valleys

36

surface area

Claims (5)

Method for producing a brake disk ( 10 ) for a disc brake of a motor vehicle, in particular a passenger car, in which a brake disc hub ( 14 ) of a thin-walled sheet with a friction ring ( 12 ) is made of a casting alloy, in particular of gray cast iron, wherein the brake disk pot ( 14 ) is pre-machined prior to joining, in particular by grinding or fine turning, characterized in that after machining a surface ( 16 ) of the brake disk pot ( 14 ), in particular a contact surface ( 16 ) of the brake disk pot ( 14 ) for a wheel hub, is smoothed. A method according to claim 1, characterized in that for smooth rolling a steel or hard metal roller ( 32 ) is used. A method according to claim 1 or 2, characterized in that the smooth rolling is carried out until a roughness of the surface ( 16 ) is less than 1 micron. Method according to one of claims 1 to 3, characterized in that during the finish rolling the surface roughness of the surface ( 16 ) is roughly halved. Method according to one of claims 1 to 4, characterized in that for smoothing a rolling tool with a plurality of rollers ( 32 ) is used.

Images