Process for producing a brake disk

Abstract

The invention relates to a process for producing a brake disk for a vehicle, in which a friction layer is arranged at least in certain regions on a base body of the brake disk.

Claims

1. A process for producing a brake disk for a vehicle, in which a friction layer is arranged at least in certain regions on a base body of the brake disk, said process comprising at least the following steps: pre-machining the base body at least in certain regions; heating the base body; dipping the heated base body in a melt comprising base metal alloys, such that a functional layer is formed between the base body and a friction layer still to be applied, and applying the friction layer at least in certain regions by use of thermal spraying processes.

2. The process as claimed in claim 1, wherein the entire base body is dipped in the melt such that the entire base body is covered completely with the functional layer.

3. The process as claimed in claim 1, wherein the base body is heated to a temperature of between 500 C. and 700 C. in a protective gas atmosphere.

4. The process as claimed in claim 1, wherein, in a further step after the base body has been dipped in the melt, at least a brake rim thereof is machined to dimension, it being possible for the functional layer to have a thickness of 200 m after finishing.

5. The process as claimed in claim 1, wherein the melt comprises aluminum and/or zinc alloys.

6. The process as claimed in claim 1, wherein the friction layer is applied by use of high-temperature flame spraying.

7. The process as claimed in claim 1, wherein the friction layer is produced by use of the application of hard material powders, the friction layer having a thickness of 30 m to 50 m.

8. The process as claimed in claim 1, wherein particles protrude at least partially from the friction layer and/or wherein the friction layer has incorporated particles, the diameter of which is greater than the thickness of the friction layer, such that the particles protrude from the friction layer.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

(1) Further advantageous details and effects of the invention will be explained in more detail below on the basis of various exemplary embodiments illustrated in the figures. In the figures:

(2) FIG. 1 is a schematic illustration of a brake disk according to the invention in a plan view,

(3) FIG. 2 shows a ventilated brake disk in a perspective view,

(4) FIG. 3 shows the brake disk shown in FIG. 2 in a partial sectional view, and

(5) FIG. 4 shows an enlarged view of the section which can be seen in FIG. 3.

(6) In the different figures, identical parts are always provided with the same reference signs, and so said parts are generally also described only once.

DETAILED DESCRIPTION

(7) FIG. 1 shows a schematic illustration of a brake disk 1 according to the invention. Said brake disk has a circular base body 2 made, for example, of cast iron, i.e. for example of gray cast iron (GCI). The base body 2 typically has a circumferential outer brake rim 3, which is provided for contact with a brake lining (not shown in greater detail). An opening 4 is provided in the center of the base body 2, arranged in a protrusion 5 of the base body 2. The protrusion 5 may also be referred to as a disk cap structure 5. In the present case, five passage holes 6 through the protrusion 5 are arranged around the opening 4 at uniform intervals. Said passage holes 6 serve for receiving wheel bolts (not shown in greater detail here), by way of which the brake disk 1 can be connected together with a wheel (not shown) to a wheel hub (likewise not shown).

(8) FIG. 2 shows a brake disk 1 having cover disks 7 and 8 between which there are arranged ribs 9, such that a ventilated brake disk 1 is formed. The cover disks 7 and 8 each have the brake rim 3 on the outer side.

(9) FIG. 3 shows a partial section of the internally ventilated brake disk 1 shown in FIG. 2.

(10) A functional coating 10 can be seen. The functional coating 10, which can also be referred to as adhesion-promoter layer 10, has been applied over the entire brake disk 1.

(11) For the application of the functional coating 10, the brake disk 1 was preferably heated to a temperature of 500 C. to 700 C. under a protective gas atmosphere. The brake disk 1 thus heated was dipped in a base metal molten bath. The molten bath can be an aluminum and/or zinc alloy melt.

(12) After the dip bath, the brake disk 1, at least the brake rim 3 on which the braking surfaces are arranged, was machined to dimensions, the functional layer 10 preferably still having a thickness of 200 m at the brake rim 3 after the machining.

(13) The brake disk 1 was dipped completely in the hot-dip bath, such that all regions, i.e. all components 2 to 6, are also covered with the functional layer 10. In the case of the internally ventilated brake disk 1 in particular, it is the case that the two cover disks 7 and 8 are covered with the functional layer 10 not only externally but also internally. Moreover, the ribs 9 are also covered with the functional layer 10.

(14) The brake disk 1 thus also has corrosion protection, as it were, outside the respective brake rim 3.

(15) In a further production step, the brake disk 1, in particular the respective brake rim 3, i.e. preferably the friction surfaces, was coated by means of thermal spraying processes. In this case, hard material powders were applied by means of high-velocity flame spraying (HVOF) at least in the region of the friction surfaces having the adhesion-promoter layer 10.

(16) In the region of its friction surfaces, the brake disk 1 thus preferably has a friction layer 11 applied by means of the preferred HVOF process and having a thickness of 30 m to 50 m. The hard material powders are injected with incorporated sharp-edged particles 12 into the soft adhesion-promoter layer 10 by means of the HVOF, so as to give rise to an intimate (mechanical) bond between the hard material particles and the adhesion-promoter layer 10.

(17) The hard material particles 12 have sharp edges and have a diameter which is greater than the thickness of the friction layer 11. The particles 12 thus protrude from the surface of the friction layer 11 (FIG. 4). As can furthermore be seen in FIG. 4, some particles 12 also mesh with the soft adhesion-promoter layer 10, it also being the case that some particles 12 are embedded in the friction layer 11, i.e. do not protrude. The particles 12 which can be seen in FIG. 4 have a diameter which is smaller than the thickness of the friction layer 11, but nevertheless protrude from the friction layer 11.

(18) During a braking operation, during which brake linings come into contact with the friction surface, i.e. in the present case with the friction layer 11, brake lining material is torn out of the brake lining on account of the action of the sharp-edged particles 12 and transferred onto the surface of the friction surfaces, such that a transfer film or a transfer layer is formed. This transfer film embeds the microrough surface. The transfer film remains on the surface and thus protects the brake disk 1, i.e. the adhesion-promoter layer 10, against wear. The brake lining, by contrast, is in the form of a wear part and constantly delivers new material for stabilizing the transfer film.