SI20167A - Breaking disk and the procedure for its manufacturing - Google Patents

Abstract

The breaking disk is meant to be used in smaller motor driven vehicles, particularly go-carts, where compared to currently known solutions it should be considerably lighter and feature improved physical properties therefore providing a number of technical advantages. Such a disk includes at least two disk areas (1, 2) which are at a certain distance, where each time there is at least one friction surface (10, 20) available, as well as appropriately distributed cooling ribs (3) between them. By this the breaking disk operates as an axial-radial fan. This provides an appropriate air throughput through the disk, which ensures effective cooling. This way the temperature on the disk surface during breaking is lower, thus providing lesser thermal stress to the brake linings, while additionally a more stable friction factor or enhanced efficiency of the breaking assembly is provided. For this purpose at least one disk area (1, 2) located directly next to the ribs (3) is equipped with a step-like rounding (11), the ratio between the width or thickness (b) of each disk area (1, 2) and the distance (c) between the disk areas (1, 2) is between 0,8 and 1,2. The disk is manufactured through a casting process from light composite material, the so-called Al.MMC and during mechanical processing or even after it, if required, it can be subject to additional thermal and/or surface finishing.

Description

Brake disc and manufacturing process

The invention relates to a brake disk, in particular for smaller vehicle motos, in particular for smaller vehicle racing motors, namely the so-called go-karts. At the same time, the subject of the invention is a method of manufacturing such a brake disc.

The invention is based on the problem of how to design a brake disk, which will be useful for smaller rival motor vehicles, especially go-karts, whereby the brake disk, in comparison with the known solutions, is expected to offer significantly improved physical properties and from the results thereof. technical advantages.

In the case of braking assemblies of smaller competing motor vehicles, e.g. Go-karts, so far, have used brake discs made of either cast iron or stainless steel or also aluminum. Full-disk versions are known, as well as embodiments due to the possibility of cooling formatted or. from at least two annular zones of standing brake discs. The braking surfaces of the known disks were also broken down and, for this purpose, equipped with notches, studs or also with differently spaced circular grooves. The purpose of such a breakdown of the brake disc surfaces is primarily to remove linings, which are caused especially by more intensive braking when the temperature of the brake surfaces rises even to 400-500 ° C.

The formation of these liners, however, is not the only drawback of the gray cast iron discs used so far. Gray cast iron is a material that, on the one hand, has a really good casting ability and, on the other hand, relatively good physical properties. The fact is that this material is of relatively high density or density. specific gravity. Therefore, gray alloy brake discs are relatively heavy, which is a major drawback especially when used in light racing vehicles. Adverse effects are manifested mainly in high rotational masses or. inertia when accelerating or braking, as well as in relatively high dynamic loads of individual vehicle components. On the other hand, gray cast iron as a material can also be problematic in view of the adverse effects of relatively poor thermal conductivity. During braking, it is inevitable that thermal energy is concentrated, which is concentrated in the brake assembly, to a great extent in the disc itself. Increasing the temperature of the sliding surfaces results in, among other things, a decrease in the coefficient of friction and the braking efficiency, while at the same time the formation of the already mentioned deposits and also an increase in the wear of the disc surfaces.

The disadvantages described were otherwise sought to be avoided either by the application of wear-resistant linings (DK 1891/88; CH 312,880 or FR 8011,646; DK 7790;) by the insertion of segments (EP 0 030 791 Al) or by specific follow-up operations treatment of brake disc surfaces to provide abrasion resistance (DK 77/90; DK 189188; EP 0 742 379 Al), better thermal conductivity (DE 4.426.091) or directly prevent the formation of said liners (FR 9.403.972). By all means, every effort was made to try and improve the problem of ensuring the best physical properties of the brake disc, in all of the above cases the problem of a relatively high weight of the disc remains, and the resulting adverse consequences are completely unsolved.

The problem of the weight of the brake disks has been faced in recent years especially by manufacturers of brake discs for heavier vehicles, e.g. railway locomotives and the like, where significant number of discs on the vehicle can create significant savings in vehicle weight, fuel consumption and the like. As a consequence, the so-called composite materials (EP 0 705 397 Al) were introduced on the brake discs in addition to other alloys (EP 0 868 538 Al). These composite materials are lighter, but in most cases more difficult to cast and more demanding to provide all the necessary mechanical properties. The problem of demanding casting is not so much the case with full discs (EP 0 705 397 Al) of relatively simple design. However, e.g. in the brake discs of competing vehicles, it is necessary to take into account that the full disks do not allow sufficient heat dissipation and, therefore, the formally split, cooled disks are inevitably needed.

Knorr Bremse, together with Honsel, recently introduced brake disks made of Al-MMC material for high-speed (so-called ICE) trains in Germany. The design of these brake discs is adapted to the running characteristics of the ICE trains. The method of construction and construction of brake discs is described in Giesserei 85, (1998), Nr. 2, February 10 and Giesserei 85, (1998), Nr. 3, 10. Margin. Driving and braking characteristics of light motor vehicles, especially racing vehicles, e.g. go-karts and the like differ significantly from the stated properties of high-speed trains, so the described design solutions in the desired area cannot be used in any way.

According to the invention, the brake disk is implemented in a new and substantially improved structural design, and at the same time consists of appropriate material described below, and at the same time is performed according to a procedure, which will also be explained in more detail below. The disk consists of at least two parallel spaced annular regions, the outer surfaces of which each represent the corresponding friction surfaces. There are ribs between the two annulus areas which help to improve ventilation and / or ventilation. air circulation between the annular areas. In addition, the characteristic stepped rounding, which is available in one of the aforementioned disc areas in the immediate vicinity of the ribs available, also contributes to the improvement of circulation. In doing so, each of said edges - viewed radially inwardly toward the center of the disk - can be made either with a straight end zone or with a considered end zone. In this way, the brake disk acts as an axial-radial fan during rotation, ensuring adequate airflow through the disk, resulting in efficient cooling. In this way, the temperature on the surface of the disk is lower during braking, the lower the thermal loads of the brake lining material, the more stable the coefficient of friction and / or friction are. increased efficiency of the brake assembly. Taking into account the requirements for selecting the appropriate material and technological process for making the brake disc, the problem described above is solved, inter alia, by the ratio between the thickness of each of said annular areas and the distance between said regions between 0.8 and 1.2 and preferably about 0.9.

An aluminum composite material, as defined in the literature (Knorr Bremse and Honsel - Giesserei 85, (1998), Nr. 2, 10 February and Giesserei 85, (1998), Nr. 3, 10, is used to make the brake disc according to the invention. .), abbreviated as Al-MMC, and marketed under the trademark Duralcan®. Specifically, for example, for Al-MMC or. Duralcan® type F3S.20S containing 20 parts by volume of SiC particles or e.g. Duralcan® type F3K.20S containing Cu alloy with aluminum alloy. Casting into the molds is possible as well, while in the manufacture of the disks of the pre-defined structural design from the mentioned material, the sand casting process is undoubtedly quite useful, whereby the basic furnace melts

Al-MMC material, which is slowly and continuously mixed during the casting process. The melt temperature prior to sand casting is preferably 725-735 ° C. The molds are equipped with suitable ceramic cast filters with a porosity of 20 PPI. In sand form it is necessary to arrange the power supply and the vents properly, as this can only ensure that the cast does not contain any inclusions of pores or air. Generally speaking, it can be made - as mentioned - a brake disc made of Al-MMC material by casting into a mold using either the conventional casting method (using the weight of the melt itself) or the low-pressure casting process. After casting, the raw castings of the brake discs are cleaned of sand and then mechanically machined to predetermined dimensions, preferably using diamond or pine carbide based machining tools.

In addition, further improvements to the physical and thus technical properties of Al-MMC brake discs are possible according to the invention. This is mainly due to the increase of the hardness on the surface of the disk, which is achieved by hard anodic oxidation, and it is also possible to increase the hardness of the surface by ion nitration. The treated surface is even more resistant to abrasion and has improved abrasion resistance.

The invention also provides for the subsequent thermal treatment of the disks at a temperature of 400 ° C for 2 hours and a reduction of the internal stresses in the aluminum matrix for 6 hours at a temperature of 160 ° C. In this way, the mechanical strength of the composite material is improved and the elongation or elongation is increased. reduce product fragility.

The use of an alternative aluminum composite material, Duralcan® type F3K.20S, containing an aluminum alloy with Cu added, will further increase the mechanical strength and even better the thermal stability of the brake disc.

Brakes are also made of this material by means of sand casting and subsequent mechanical treatment.

The invention will now be explained in more detail on the basis of specific examples of the disks shown in the accompanying drawing, in which Figs. 1 shows a first example of a cross-sectional embodiment of the brake disc in the diametrical plane; FIG. 2 is another example of a brake disc embodiment, also in cross section in the diametrical plane. In addition, the process of making such a disc, with all the essential steps of the invention, will be explained on the basis of specific examples and supported by the results obtained.

As can be seen in FIG. 1 and 2, the brake disc according to the invention is made of two spaced discs 1, 2 in parallel. The outer surfaces 10, 20 thereof represent friction surfaces, where during the braking with their friction surfaces, the available retaining parts of the brake assembly are pressed. Ribs 3 are provided between the two annular zones 1, 2 which help to improve ventilation and / or ventilation. the circulation of air between zones 1, 2 during braking, and thus to more intense heat dissipation from the annular zones 1, 2 and. from the brake disc. In particular, stepwise rounding 11, which is available in one of the aforementioned reel regions 1, 2 in the immediate vicinity of the ribs available at all times 3, contributes to the improvement of circulation.

In doing so, each of said ribs 3 - viewed radially inwardly toward the center of the disk - can be made either with a straight end zone 30 (Fig. 1) or with a considered end zone 30 '. The choice between the possible embodiments of the zones 30, 30 'also affects the efficiency of the brake assembly and depends primarily on the expected air circulation regime between the brake disk disc regions 1, 2.

As can be seen in FIG. 1, is the width or. the thickness of the annular regions 1, 2 indicated by b, the spacing respectively. the axial distance between zones 1 and 2 by c. Taking into account the following requirements regarding the selection of the appropriate material and technological procedure for the manufacture of the brake disk, the problem posed above is also solved by the fact that the ratio of the thickness b of each of the two annular regions 1, 2 and the distance c between 0.8 and 1 , 2. In the given embodiments, the ratio b / c = 0.9.

For the manufacture of the brake disc according to the invention, aluminum composite material was used (see Knorr Bremse, Honsel - Giesserei 85, (1998), Nr. 2, February 10, and Giesserei 85, (1998), Nr. 3, 10. Margin.) , hereinafter referred to as Al-MMC, and marketed under the Duralcan® brand. More specifically, it is AlMMC or. Duralcan® type F3S.20S containing 20 volumes of SiC particles. We used a sand casting process and previously melted the basic Al-MMC material in an aluminum smelter and mixed it slowly and continuously during the casting process. The melt temperature before pouring into the sand form was 725-735 ° C. The molds had to be fitted with suitable ceramic cast filters with a porosity of 20 PPI. In sand form, the power supply and vents were appropriately arranged to ensure that the cast did not contain any inclusions of pores or air. In general, a brake disc of Al-MMC material can also be fabricated by die casting using either the conventional casting method (weight of the melt itself) or the low pressure casting process. After casting, the raw castings of the brake discs were cleaned and blasted and then machined to predefined dimensions. In this case, we used diamond and / or pine carbide based machining tools.

An additional increase in hardness on the surface of the disk was achieved by hard anodic oxidation, and it is also possible to increase the surface hardness by ionic nitration. The treated surface is even more resistant to abrasion and has improved abrasion resistance.

In addition, we were able to further improve the mechanical strength of the composite material and increase the elasticity or elasticity of the composite material. reduce the fragility of the product by subsequent thermal treatment of the discs at 400 ° C for 2 hours and then loosen the internal stresses in the aluminum matrix for approximately 6 hours at 160 ° C.

On the other hand, an alternative material was used in the manufacture of the brake disc, as described above, namely the aluminum composite material Duralcan® type F3K.20S, which contains an aluminum alloy with Cu added, resulting in even higher mechanical strength and an even better temperature. brake disc durability. Also made of this material are brake discs by sand casting and subsequent mechanical treatment.

To test the friction properties of the manufactured brake disks, we used the Sinter MMC 2032 and Sinter F3000 brake pads, which were developed taking into account the properties of Al-MMC materials.

Example 1:

In this case, it is a construction of a brake disk, in which the ratio of the thickness to the spacing of the disc zones 1, 2, namely the ratio b / c. was 0.9. The first embodiment of the rib shape 3 according to FIG. On this basis, the preparation of the form was carried out. mold. As part of this process step, a model and a core were made, followed by the manual fabrication of cores from a mixture of silica sand and water glass, and then the cores were cured with CO ₂ . The cores can also be derived from a mixture of sand and the corresponding phenolic resins. The cores were air-dried overnight and can also be dried in an oven for 150 hours at 150 ° C. With the help of the upper and lower part of the model, we made the upper and lower part of the sand form. We combined the two parts of the form and inserted a pre-made kernel in between. In the sand form, we also designed a casting system with a ceramic filter 20PPI as well as air vents. Meanwhile, ingots of Al-MMC type F3S.20S were specially preheated in the 200250 ° C preheating oven. We put such preheated ingots in an already heated aluminum smelter and waited for them to melt. After about 1 hour (in general, this may depend, of course, on the amount and volume of the furnace), the melt was carefully mixed until the SiC particles were evenly distributed throughout the melt. Subsequently, the resulting slag was taken from the surface of the melt, and at a melt temperature of 725-735 ° C, we began casting into preformed molds. After each cast had cooled, it was taken out of shape, the sand core was removed and the surface was sandblasted. This was followed by finishing with turning to the required dimensions. In this case, diamond-tipped knives were used.

The friction properties of Al-MMC brake disks were tested on an automatic Krauss RWS 75B brake element testing machine according to the standard ECE R90 annex 8 test program with Sinter type MMC 2032 or Sinter type F3000 brake pads. The results of the measurements are given in Tables 1 and 2.

Example 2:

The procedure was the same as in Example 1, except that in this case aluminum composite material (Al-MMC) Duralcan® type F3K.20S was used. The results of the frictional properties of the brake discs thus produced according to the invention are again given in Tables 1 and 2.

Example 3:

The procedure corresponds to that in Example 1, except that the finally treated brake disc made of AlMMC material was subsequently anodized hard at an bath temperature of 0 ° C and with a gradual increase in voltage from 20 to 100 V. The thickness of the A1 ₂ O ₃ hard coating was between 20 and 30 μιη. The results of the friction properties of the brake discs thus obtained are given in Tables 1 and 2.

Example 4:

We proceeded as in Example 1, except that the final treated disk of Al-MMC material was subsequently ionically nitrated at 390 ° C for 12-14 hours under an atmosphere of Ar and NH ₃ . The A1N hard coating thickness was approximately 30 pm. The results of the friction properties of the brake discs according to the invention are again given in Tables 1 and 2.

Example 5:

The procedure was the same as in Example 1 and / or Example 2 except that only the partially treated Al-MMC brake disc was subsequently heat treated at 400 ° C for about 2 hours and then allowed to cool at 160 ° C for 16 hours. . Finishing to the final dimensions followed. The results of the frictional properties of the brake discs thus obtained after heat treatment are given in Tables 1 and 2.

The friction properties of the Al-MMC materials of the manufactured brake discs according to the invention are presented in the table below in accordance with the relevant conditions (Test ECE R90 annex 8).

n

Braking pads:

Sinter ident: 11-420-00 Mass type: MMC 2032

Measurement Specifications: Brake System: Tonykart

Disk:

Effective radius:

Lining surface:

Specific pressure:

Hydraulic pressure:

Number of revolutions: 660 mi

207x14 mm mm 22.4 cm ² 65 N / cm ² 20.8 bar

Features Example 1 Example 2 Example 3 Example 4 Example 5 Mean friction coefficient (μ _0Ρ ) 0.39 0.38 0.36 0.35 0.39 Minimum friction keofic. (p _m j _n ) 0.25 0.24 0.19 0.21 0.26 Maximum friction coefficient. (p _ma x) 0.52 0.50 0.53 0.51 0.49 The friction coefficient. at max. temp (pF) 0.39 0.38 0.20 0.25 0.39 The friction coefficient. cold (μ «) 0.35 0.34 0.35 0.33 0.36 Maximum temp. during the test (° C) 297 290 292 287 289 Specific plate wear: oily (g / MJ) 0.15 0.17 0.23 0.15 0.20 • i dimensional (mm / MJ) 83 90 85 70 87 Assessment of resistance to smashing good z. good great great z. good

(Table 1)

The friction properties of the Al-MMC materials of the manufactured brake discs according to the invention are given in the table below in accordance with the relevant conditions (Test ECE R90 annex 8) and at the same time compared to those of the gray cast iron (from the brake plate under the code Sinter 114).

Braking pads:

Sinter ident: 11-420-00

Type of mass: F 3000

Measurement specifications: Braking system: Tonykart Disk: 207x14 mm Effective radius: 85 mm Lining surface: 22,4 cm ² Specific pressure: 65 N / cm ² Hydraulic pressure: 20,8 bar Number of revolutions: 660 min ' ¹

Features Example 3 Example 4 Gray cast iron * Mean friction coefficient (μορ) 0.44 0.43 0.45 Minimum friction keofic. (p _m j _n ) 0.17 0.19 0.30 Maximum friction coefficient. (p _ma x) 0.75 0.60 0.61 Tomi coefficient. at max. temp (pp) 0.49 0.43 0.45 Tomi coefficient. cold (μ _κ ) 0.39 0.37 0.37 Maximum temp. during the test (° C) 314 302 387 Specific plate wear: oily (g / MJ) 0.80 0.60 0.66 dimensional (mm ³ / MJ) 250 180 196 Assessment of resistance to smashing z. good z. good -

(Table 2)

The brake disc, prepared in accordance with Example 1 and in combination with the MMC 2032 brake discs, is characterized by a high mean friction coefficient μ _Ο ρ, low specific plate wear and satisfactory tear resistance. In the event of replacement of Al-MMC material (Example 2) or subsequent heat treatment of the brake disk (Example 5), the friction properties do not change significantly, and partially the resistance to tearing is improved. Both can be related to the improved mechanical properties of the matrix aluminum alloy (type F3K.20S) or to the structural changes of the matrix alloy after heat treatment. The advantage of heat treated disks is the reduced material fragility (Table 1). The brake discs prepared in accordance with Examples 3 and 4 and in combination with the MMC 2032 brake discs have a slightly lower mean friction coefficient (10-15%), but excellent resistance to tearing. The specific wear of the MMC 2032 is also low (less than 100 mm ³ / MJ). The measurement results are listed in Table 1. Higher values of the mean friction coefficient μ _0Ρ were measured on the brake discs made in accordance with Examples 3 and 4 in combination with the Sinter F3000 brake pads. Values exceeded 0.49 but, on the other hand, specific plate wear was almost twice as high (Table 2). The blasting resistance was good but worse than in the case of the MMC 2032 type brake pads. Table 2 lists the friction properties of the cast iron disc in combination with the classic Sinter 114. brake pads. It is obvious that the maximum temperatures measured between tests on brake discs according to the invention, at least 90 to 100 ° C lower than the gray cast iron discs used so far. Therefore, we have the advantage of braking at significantly lower temperatures, which enables us new construction, material selection and the process of making a brake disc according to the present invention.

Claims (13)

PATENT APPLICATIONS A brake disc, in particular for light motor vehicles, in particular for light racing vehicles, namely go-karts, comprising at least two spaced disc regions (1,2) each having at least one friction surface (10, 20) ) and between which there are suitably arranged cooling fins (3), characterized in that in the case of a brake disk having at least one disc area (1, 2) provided with a stepped rounding (11) directly adjacent to the ribs (3) , is the ratio of width to width. the thickness (b) of each disc region (1, 2) and the spacing (c) of each disc area (1,2) between 0.8 and 1.2, the disc being made by the casting process of lightweight Al-MMC composite material and prior to at least a portion of the necessary mechanical machining steps, or subjected to additional heat and / or surface treatment, at least every time. Brake disc according to claim 1, characterized in that, in the case of a brake disc whose at least one disc region (1, 2) is provided with a stepped rounding (11) directly adjacent to the ribs (3) and each of which is between disc regions (1, 2) of the located ribs (3) when viewed radially inwardly with a rounded stepped end (30 '), is the ratio of width to width. a thickness (b) of each disc region (1, 2) and a spacing (c) between each disc area (1, 2) between 0.8 and 1.2, the disc being made by the casting process of lightweight Al-MMC composite material and prior to at least a portion of the necessary mechanical machining steps, or subjected to additional heat and / or surface treatment, at least every time. Brake disc according to claim 1, characterized in that in the case of a brake disc whose at least one disc region (1, 2) is provided with a stepped rounding (11) directly adjacent to the ribs (3) and at least part of which is between discs the areas (1, 2) of the located ribs (3), viewed radially inwards, designed with a rounded stepped end (30 '), is the ratio of width to width. a thickness (b) of each disc area (1, 2) and a spacing (c) between each disc area (1, 2) between 0.8 and 1.2, preferably at least about 0.9, wherein the disc is manufactured by the method castings made of lightweight Al-MMC composite material and subjected, at least in part, to the necessary mechanical processing steps, or subjected to additional thermal and / or surface treatment, at any time. 4. A method of manufacturing a brake disc, comprising the step of preparing a mold or a mold. molds, casting steps and mechanical machining steps to predetermined dimensions, characterized in that Al-MMC or Al-MMC is used as the starting material for the production of the disc. Duralcan® type F3S.20S containing 20 parts by volume of SiC, in which the model and the core as well as the cores are made in the form or mold preparation step, either from a mixture of sand and each corresponding phenolic resin or from a mixture of silica sand and water glass then hardens with CO ₂ and then dries, after which the upper and lower part of the sand form is formed and the latter is assembled and a pre-fabricated core is inserted and a 20PPI ceramic filter as well as air outlet openings are used in the mold after the molding system is formed. preheating at 200-250 ° C, the ingots from Al-MMC are inserted into an already heated melting furnace and melted there, and after about 1 hour, the melt is stirred to distribute the SiC particles evenly over the melt surface, and then, after the slag is formed, the melt temperature between 725 and 735 ° C begins casting into pre-made molds, after which the castings are cooled and the molds are blown apart, cleaned and, if necessary, blasted perform the necessary mechanical machining steps of castings using diamond and / or pine carbide based cutting tools. 5. A method of manufacturing a brake disc, comprising the step of preparing a mold or a mold. molds, casting steps and machining steps to predetermined dimensions, characterized in that the aluminum composite material Duralcan® type F3K.20S, containing aluminum alloy with Cu addition, is used as the starting material for the production of the disc, using the Cu alloy in the form preparation step or molds are made by the model and core as well as cores, either from a mixture of sand and corresponding phenolic resins, or from a mixture of silica sand and water glass, which is cured with CO ₂ and then dried, and then the top and bottom of the sand form and the latter are formed. insert a pre-fabricated core and use a 20PPI ceramic filter in the form after casting, as well as air outlet openings, then in the casting step after preheating at 200-250 ° C, ingots from Al-MMC are inserted into an already heated melting furnace and there melt, and after about 1 hour stirring of the melt begins to distribute the SiC particles evenly over the melt surface, after which the slag is formed after recording re at a melt temperature of between 725 and 735 ° C begins casting into preformed molds, after which the necessary mechanical machining steps of the castings are performed after the casting has cooled and the molding, sanding and, where necessary, sanding using diamond-based cutting tools and / or pine carbide. Method according to claim 4 or 5, characterized in that in the casting step, after heating at 200-250 ° C, the ingots from Al-MMC are inserted into an already heated melting furnace and melted there, and after about 1 hour they start mixing of the melt in order to distribute the SiC particles evenly over the melt surface, after which the slag at the melt temperature between 725 and 735 ° C begins to be cast into pre-fabricated molds and after each step the mechanical steps are taken after cooling the castings and cleaning them. casting processing using diamond and / or pine carbide based cutting tools. Method according to claim 6, characterized in that in the casting step after preheating at 200-250 ° C, the ingots from Al-MMC are inserted into the already heated melting melt and after about 1 hour mixing of the melt is started in order to distribute the particles evenly. SiC at the melt level, after which the slag at the melt temperature between 725 and 735 ° C is shot after casting into pre-fabricated molds, and after each step of machining the castings with the help of cutting tools, based on diamond and / or boron carbide, after which the finished workpiece is further oxidized hard anodically at a bath temperature of 0 ° C while increasing the voltage from 20 to 100 V and providing a hard coating of A1 ₂ O ₃ with a thickness between 20 and 30 pm. The method according to claims 4-6, characterized in that the finally treated brake disc of Al-MMC is ionically nitrated at 390 ° C for 12-14 hours in an atmosphere of Ar and NH ₃ . A method according to claim 7, characterized in that the pretreated brake disc of AlMMC is ionically nitrated at 390 ° C for 12-14 hours in an atmosphere of Ar and NH ₃ . The method according to claims 4 - 7, characterized in that only the partially machined Al-MMC brake disc is subsequently heat treated at a temperature of 400 ° C for at least about 2 hours and then released at 160 ° C for 6 hours. 11. A brake disc, characterized in that at least one disc region (1,2) is provided directly with the ribs (3) provided with a stepped rounding (11) and that it has a width / width ratio. a thickness (b) of each disc region (1, 2) and a spacing (c) between each disc area (1,2) of between 0.8 and 1.2, preferably at least about 0.9, wherein the disc consists of a lightweight composite materials AlMMC or. Duralcan® and is made by casting after preheating at 200-250 ° C in sand form or mold at a melt temperature of between 725 and 735 ° C and then machining castings using diamond and / or pine carbide based cutting tools and is thereafter, if necessary, hard anodically oxidized at a bath temperature of 0 ° C with increasing voltages from 20 to 100 V and providing a hard coating of A1 ₂ O ₃ with a thickness between 20 and 30 pm. 12. Brake disc, characterized in that for a disc whose at least one disc region (1, 2) is provided with a stepped rounding (11) directly adjacent to the ribs (3), the ratio of width to width is 12. a thickness (b) of each disc area (1,2) and a spacing (c) between each disc area (1,2) of between 0.8 and 1.2, preferably at least about 0.9, wherein such disc is derived from lightweight Al-MMC composite material Duralcan® by casting after preheating at 200250 ° C in sand or mold at a melt temperature between 725 and 735 ° C and then subjected to mechanical casting using diamond and / or pine carbide-based cutting tools and then ion-nitrided if necessary 390 ° C for 12-14 hours under Ar and NH ₃ atmosphere. 13. Brake disc, characterized in that in the case of a brake disc whose at least one disc area (1, 2) is provided with a stepped rounding (11) directly adjacent to the ribs (3), it has a width / width ratio. the thickness (b) of each disc area (1, 2) and the spacing (c) of each disc area (1,2) between 0.8 and 1.2, wherein such disc is made of lightweight Al-MMC composite material. Duralcan® by casting after preheating at 200-250 ° C in sand or mold at a melt temperature between 725 and 735 ° C and then subjected to mechanical machining of castings using diamond and / or pine carbide-based cutting tools and then only partially treated condition, if necessary, heat treated at a temperature of 400 ° C for at least about 2 hours and then at 160 ° C for at least about 6 hours. For: