Brake disc for friction brake of motor vehicle and method for producing brake disc

Abstract

The invention relates to a brake disc (1) for a friction brake of a motor vehicle, comprising a base body (10) made of gray cast iron or steel, a fastening section (11) for vehicle-side fastening of the brake disc (1) and a friction section (12) having at least one friction surface (31) being formed on the base body (10). The friction surface (31) is used for abutting against a brake lining in the assembly position of the brake disc (1). The friction section (12) has a first structural layer (20) made of stainless steel and a second structural layer (30) made of a composite of an iron alloy matrix and embedded hard particles. According to the invention, the second structural layer (30) has a continuous radial surface extension (F) which is smaller than the continuous radial surface extension (F) of the first structural layer (20). The invention further relates to a method for producing the brake disc according to the invention.

Description

Technical Field

[0001] This invention relates to a brake disc for a friction brake in a motor vehicle. The invention also relates to a method for manufacturing the brake disc. Background Technology

[0002] Brake discs are typically made of gray cast iron. The advantages of gray cast iron, especially its high volumetric heat capacity and relatively good thermal shock resistance, are accompanied by various disadvantages. These disadvantages include high weight, strong corrosion susceptibility, and high material wear during vehicle operation.

[0003] Corrosion causes visual defects because brake discs are the only part of a vehicle that develops red rust in a very short time. Additionally, brake discs are directly visible due to the often-used open-faced aluminum alloy rims.

[0004] In cases of economical driving or a large recycling rate (when braking is infrequent), the corrosive properties of the material can cause such significant damage to the brake body that it must be replaced prematurely.

[0005] In addition, frictional wear of the brake discs can lead to the emission of particulate matter, which may be significantly higher than the particulate emissions from modern internal combustion engines.

[0006] To eliminate these drawbacks, various solutions have been adopted to date, including replacing the brake disc material entirely with a harder and corrosion-resistant material (such as ceramic) and brake disc friction surfaces with suitable coatings.

[0007] Thus, a brake disc for motor vehicles is known from DE 10 2021 207 B3, on which two structural layers are applied to the face side by laser cladding welding. The structural layers form a surface that serves as a friction surface for brake pads in the assembled state of the brake disc in the motor vehicle. The basic body of the brake disc is made of gray cast iron, wherein the first structural layer is made of austenitic chromium-nickel-molybdenum steel. The second structural layer is composed of a composite material consisting of an iron alloy matrix and embedded tungsten carbide particles.

[0008] DE 10 2021 214 946 A1 describes a brake disc for a friction brake in a motor vehicle, the brake disc having a friction section with a friction surface and a fastening section for fastening to the vehicle side. The friction section and the fastening section are constructed on a base body made of gray cast iron or steel. As the friction surface, a wear protection layer is applied to the base body at the friction section by laser cladding welding. The wear protection layer extends beyond the friction surface into and ends in an angled region with respect to the friction surface. In the angled region of the base body, the wear protection layer is applied in a covering manner and without gaps to the base body. A corrosion protection layer may be provided on the surface section outside the friction surface, which overlaps with the wear protection layer in the angled region. Summary of the Invention

[0009] This invention aims to provide a brake disc for a friction brake in a motor vehicle, which possesses good wear resistance and corrosion resistance. A further objective of this invention is to provide a suitable method for manufacturing such a brake disc.

[0010] These tasks are accomplished via a brake disc with the following characteristics: A brake disc for a friction brake in a motor vehicle has a basic body made of gray cast iron or steel, wherein a fastening section for vehicle-side fastening of the brake disc and a friction section having at least one friction surface are constructed on the basic body, wherein the friction surface is used to abut against a brake pad in the mounting position of the brake disc, and wherein the friction section has a first structural layer formed of stainless steel and a second structural layer composed of a composite material of an iron alloy matrix and embedded hard particles, characterized in that the second structural layer has a continuous radial extension that is smaller than the continuous radial extension of the first structural layer. and methods with the following characteristics: A method for manufacturing a brake disc according to the present invention, comprising the following steps: - Provide a basic body made of gray cast iron or steel, said basic body having at least a fastening section and a friction section. - A first structural layer made of stainless steel is applied to at least the friction section of the basic body by laser cladding welding. - A second structural layer is applied to the first structural layer by laser cladding welding, wherein the second structural layer consists of an iron alloy matrix and embedded hard particles. Its characteristics are as follows: - The second structural layer is applied to the first structural layer such that the second structural layer is smaller than the first structural layer in its radial extension. Let's solve it.

[0011] Regarding the brake disc, the present invention relates to a brake disc for a friction brake in a motor vehicle, having a basic body made of gray cast iron or steel, wherein a fastening section for vehicle-side fastening of the brake disc and a friction section having at least one friction surface are constructed in the basic body. The friction surface serves to abut against the brake pads in the mounting position of the brake disc. The friction section also has a first structural layer that serves as a wear protection layer. The first structural layer is formed of stainless steel. The stainless steel is preferably austenitic or ferritic stainless steel. For example, it is conceivable that the first structural layer may be made of austenitic chromium-nickel-molybdenum steel having material properties such as its corresponding material 1.4404 according to EN 10027-2 or material 316L according to AISI standards. However, depending on the material properties of the basic body of the brake disc, it is alternatively conceivable and proven advantageous that the first structural layer is made of ferritic stainless steel having material properties such as its corresponding material 1.4016 according to DIN EN 10027-2 or material 430L according to AISI standards.

[0012] The brake body also has a second structural layer, which serves as a friction layer for the brake pads in the assembly position of the brake body in the vehicle. The second structural layer is composed of a composite material consisting of a ferroalloy matrix and embedded hard particles. The ferroalloy matrix is ​​preferably composed of the aforementioned materials 316L or 430L. The hard particles are preferably composed of an alloy of titanium carbide and ferrochrome (TiC-FeCr), or may be composed solely of titanium carbide or tungsten carbide.

[0013] The structural layer is applied to the substrate by means of laser cladding welding.

[0014] The present invention proposes that the second structural layer has a continuous radial extension, which is smaller than the continuous radial extension of the first structural layer. In other words, viewed in the radial direction of the brake disc, the first structural layer is not completely covered by the second structural layer. Instead, a radial distance is maintained between the radial extensions of the first and second structural layers. Therefore, the two structural layers are coated onto their respective substrates without interruption or gaps from their respective radial starting points to their radial ending points.

[0015] This feature is based on the fundamental premise that the brake disc possesses good wear and corrosion resistance. It has been shown that by reducing the radial extension of the second structural layer, the so-called overspray area can be significantly reduced in its visible portion. The overspray area is understood as the region of the brake disc located radially next to the friction surface, where heated hard particles impact and remain attached or melt during the application of the second structural layer via laser cladding welding. Subsequent processing of these areas facilitates the application of a protective layer, preferably formed of a paint with corrosion protection. However, subsequent processing of these areas, particularly the mechanical removal of the attached hard particles, is extremely difficult. Therefore, by reducing the hard particles in these areas, subsequent processing of the coated brake disc in these areas becomes significantly easier and more efficient. This significantly simplifies the application of the protective layer.

[0016] According to a first advantageous improvement of the invention, the second structural layer has a smaller radially outer surface extension than the first structural layer. In this way, the visibility of the overspray area can be reduced, particularly in the outer peripheral region of the brake disc. The outer peripheral region of the brake disc is subjected to environmental influences to a particularly strong degree, and thus its wear resistance and corrosion resistance can be improved.

[0017] According to another improvement, it is also conceivable, additionally or alternatively, that the second structural layer has a smaller radially inward planar extension than the first structural layer. In this way, the aforementioned advantages can also be achieved in the region of the fastening section.

[0018] Finally, according to the inventive construction scheme, the second structural layer extends radially towards the radial end of the first structural layer up to a maximum of 0.1 mm, or towards the radial chamfered convergence (Fasenauslauf) of the first structural layer up to a maximum of 0.1 mm. Since the first structural layer is preferably applied to the entire friction section of the brake disc, this also means that the second structural layer extends radially towards the radial end of the friction section up to a maximum of 0.1 mm, or towards the radial chamfered convergence of the friction section up to a maximum of 0.1 mm.

[0019] The advantage of this design is that, on the one hand, it can provide a very large, resistant friction surface with a second structural layer, and on the other hand, it still achieves the advantage of low overspray.

[0020] As mentioned at the beginning, the present invention should also provide a method for manufacturing a brake disc according to the present invention.

[0021] Here, the present invention starts with a method for manufacturing a brake disc, the method comprising the following steps: - Provide a basic body made of gray cast iron or steel, which has at least fastening sections and friction sections. - A first structural layer made of stainless steel is applied to at least the friction zone of the basic body by laser cladding welding. - A second structural layer is applied to the first structural layer by laser cladding welding, wherein the second structural layer consists of an iron alloy matrix and embedded hard particles. The first structural layer is preferably made of austenitic or ferritic stainless steel. For example, it is conceivable that the first structural layer is made of austenitic chromium-nickel-molybdenum steel, which has material properties such as those corresponding to material 1.4404 according to EN10027-2 or material 316L according to AISI.

[0022] However, depending on the material properties of the basic body of the braking body, it is alternatively conceivable and proven advantageous that the first structural layer is made of ferritic stainless steel, which has material properties such as those corresponding to material 1.4016 according to DIN EN 10027-2 or material 430L according to AISI.

[0023] The second structural layer is formed by a composite material consisting of a ferroalloy matrix and embedded hard particles. The hard particles are preferably an alloy of titanium carbide and ferrochrome (TiC-FeCr). Alternatively, it is conceivable to use only titanium carbide or tungsten carbide as the hard particles.

[0024] The method according to the present invention is now characterized by the following methodological approach: - The second structural layer is applied to the first structural layer such that the second structural layer is smaller than the first structural layer in its radial extension.

[0025] In other words, during laser cladding welding of the second structural layer, the first structural layer is not completely covered by the second structural layer in the radial direction of the brake disc. In other words, the second structural layer recedes behind the first structural layer at the radially inner side and / or radially outer side of the friction zone.

[0026] In this way, the brake disc according to the invention can be manufactured safely and efficiently without incurring significant costs.

[0027] An improved version of the method proposes that, when applying the second structural layer onto the first structural layer, the radially inner edge and the radially outer edge of the first structural layer are left unreserved.

[0028] This results in a significant reduction in overspray, allowing subsequent processing to be performed in the radially inner and radially outer regions of the friction zone, or with significantly less cost.

[0029] One construction scheme of this method also proposes that areas of the brake disc undergo subsequent processing where the first structural layer is not covered by the second structural layer and where hard particles are attached. This subsequent processing includes, where possible, the mechanical removal of any remaining hard particles. Furthermore, surface finishing can also be performed thereafter. This creates the conditions for good adhesion of any corrosion-resistant protective layer that may be applied, if necessary, to these areas. Attached Figure Description

[0030] Preferred embodiments of the invention are shown in the figures and explained in more detail in the following description with reference to the figures. Further features and advantages of the invention also become apparent therefrom. Even in different figures, the same reference numerals refer to the same, similar, or functionally identical components. Corresponding or similar features and advantages are achieved here even when not repeatedly described or referenced. The figures are not, or at least not always, drawn to scale. In some figures, scale or distances may be exaggerated in order to more clearly highlight the features of the embodiments.

[0031] Among them, respectively schematically Figure 1 A cross-sectional view through the brake disc is shown. Figure 2 It shows Figure 1 Enlarged view of region II in the image. Figure 3 It shows that according to Figure 1 The illustration shows the fabrication of the second structural layer, and Figure 4 A motor vehicle with a brake disc according to the invention is shown. Detailed Implementation

[0032] First refer to Figure 1 The vehicle K is visible, equipped with a brake disc 1 according to the invention. The brake disc 1 is rotatably mounted on a wheel bracket (not shown in more detail) about a rotation axis R. Brake calipers 2 each contain a repellent brake pad (not shown), and the brake disc 1 has a friction surface constructed at its brake disc friction ring for the brake pad. Pressing the brake pad against the friction surface of the brake disc 1 causes the vehicle K to brake or stop.

[0033] exist Figure 2 The brake disc 1 is shown separately and in cross-section. The brake disc 1 rotates about an imaginary axis of rotation R. For the sake of rotational symmetry, only half of the brake disc 1 is shown.

[0034] The brake disc 1 has a basic body 10, which is preferably made of gray cast iron or steel. The basic body 10 can be radially divided into a fastening section 11 and a friction section 12. The fastening section 11 is used to fasten the brake disc 1 to the wheel bracket of the vehicle K via fastening devices not shown in more detail. The friction section 12 is used to provide a friction surface 31 for the brake pads of the brake caliper 2 (see...). Figure 1 The friction surface is pressed against it. For simplicity, only friction surface 31 is shown. The opposing friction surface 31 present in friction section 12 is omitted in the drawing.

[0035] As can be seen, the friction section 12 of the basic body 10 forms a substrate for the coating. Thus, a first structural layer 20 is applied to the surface 12a of the friction section 12. The first structural layer 20 preferably covers the entire surface 12a of the friction section 12. Only the oversprayed areas 13 and 14 are not covered by the first structural layer 20.

[0036] The first structural layer 20 is made of stainless steel and serves as a wear protection layer for the brake disc 1. Preferably, the first structural layer 20 is austenitic or ferritic stainless steel. For example, it is conceivable that the first structural layer is made of austenitic chromium-nickel-molybdenum steel, having material properties such as those corresponding to material 1.4404 according to EN 10027-2 or material 316L according to AISI standards. However, depending on the material properties of the basic body 10 of the brake disc 1, it is alternatively conceivable and proven advantageous that the first structural layer 20 is made of ferritic stainless steel, having material properties such as those corresponding to material 1.4016 according to DIN EN 10027-2 or material 430L according to AISI standards.

[0037] Furthermore, a second structural layer 30 is applied on the first structural layer 20. The second structural layer 30 serves as a friction layer for the brake disc 1 and forms the actual friction surface 31.

[0038] It should be particularly emphasized that the second structural layer 30 has a smaller radial extension F than the first structural layer 20. In the embodiment, the extension F of the second structural layer 30 is constructed such that at both the radially inner and radially outer ends of the friction section 12, the second structural layer 30 extends less radially than the first structural layer 20, i.e., it recedes behind the first structural layer 20. This results in radial distances a1 and a2, which, when viewed radially, represent the distance between the ends of the second structural layer 30 and the ends of the first structural layer 20.

[0039] exist Figure 3This can be seen more clearly in the image, which shows an enlarged section of the friction zone 12. Thus, the second structural layer 30 is also presented in more detail. For use as the friction surface 31, the second structural layer 30 is composed of a ferroalloy matrix 33 into which hard particles 32 are embedded. Ferritic or austenitic stainless steel of material 316L or 430L, as described above, is preferably also used as the ferroalloy matrix. The hard particles 32 are preferably composed of titanium carbide and ferrochrome alloy (TiC-FeCr). Alternatively, it is conceivable that the hard particles 32 are composed only of titanium carbide or tungsten carbide.

[0040] It can be seen that the radial distance a1 extends from the radial position P0 to the radial position P1. The radial position P1 marks the radial beginning of the second structural layer 30. The radial position P0 marks the starting point of the chamfered convergence portion 16 of the chamfer 15 covering the basic body 10 of the first structural layer 20. Therefore, the first structural layer 20 is not covered by the second structural layer 30 beyond the radial distance a1 and the chamfered convergence portion 16.

[0041] Similarly, the radial distance a2 extends from radial position P2 to radial position P3. Radial position P2 marks the radial end of the second structural layer 30. Radial position P3 marks the starting point of the chamfered convergence portion 16 of the first structural layer 20, which covers the chamfer 15 of the basic body 10. Therefore, the first structural layer 20 is not covered by the second structural layer 30 even beyond the radial distance a2 and the chamfered convergence portion 16. If the basic body 10 should not have a chamfer 15, the chamfered convergence portion 16 is omitted.

[0042] It is conceivable that only one of the distances a1 or a2 exists, although it is preferable to achieve both distances a1 and a2. Each of the distances a1 and a2 should preferably be sized such that it is at least about 0.1 mm.

[0043] By achieving at least one of the radial spacings a1 and a2, the corresponding adjacent overspray regions 13 and 14 can be significantly reduced (see...). Figure 1 The oversprayed areas are, as previously described, understood to be regions of the brake disc 1 located radially adjacent to the friction surface 31, where heated hard particles impact and remain attached to or melt during the application of the second structural layer 30 by laser cladding welding. These prominent oversprayed areas have historically greatly hindered subsequent processing of the brake disc 1 in these regions. Here, a remedy is created by the present invention.

[0044] exist Figure 4 The document presents how to manufacture brake discs: 1. Thus, a basic body 10 made of gray cast iron or steel is first provided, which has at least a fastening section 11 and a friction section 12. Immediately thereafter, a first structural layer 20 made of stainless steel is applied to at least the friction section 12 of the basic body 10 by laser cladding welding. Figure 4 The method steps have been completed. Laser cladding welding is performed using a suitable tool 3, through which coating material M, heated by a laser beam, is applied to the corresponding substrate. During the coating process, the base body 10 is rotated about the rotation axis R. Simultaneously, the tool 3 moves at a radial feed speed V, preferably from the inside out.

[0045] After the first structural layer 20 is applied, the second structural layer 30 is applied to the first structural layer 20 by laser cladding welding using tool 3. The second structural layer 30 consists of an iron alloy matrix and embedded hard particles. Preferably, an alloy of titanium carbide and ferrochrome (TiC-FeCr) is added as the hard particles, or alternatively, hard particles of titanium carbide or tungsten carbide are added.

[0046] It should be emphasized in this method that the second structural layer 30 is applied onto the first structural layer 20 such that the second structural layer 30 is smaller than the first structural layer 20 in its radial extension F. Thus, the coating by means of the tool 3 does not begin at the radial position P0, but rather at a distance at the radial position P1. The tool 3 is then moved further from the inside out at a radial feed rate V. At the radial position P2, i.e., at a radial distance from the radial position P3 (the end of the first structural layer 20), the coating by the tool 3 has ended.

[0047] In this way, by creating the aforementioned distances a1 and / or a2, the presence of hard particles in oversprayed areas 13 and / or 14 can be significantly reduced, or even avoided if the distances a1 and a2 are sufficiently large. As a result, subsequent processing in these areas is easier, which is beneficial for later coating and application of protective paint, etc.

[0048] List of reference numerals 1. Brake disc 2 Brake calipers 3 tools 10 Basic Subjects 11 Fastening Section 12 Friction Section 12a surface 13 Overspray area 14 Overspray area 15 Chamfer 16. Chamfered convergence section 20 First structural layer 30 Second structural layer 31 Friction Surface 32 Hard particles 33 Ferroalloy matrix a1 Radial distance a2 Radial distance F Radial Surface Extension K Motor Vehicles M coating material P0 Radial position P1 Radial position P2 Radial position P3 Radial position R Rotation axis V Radial feed rate

Claims

1. A brake disc (1) for a friction brake in a motor vehicle (K), having a basic body (10) made of gray cast iron or steel, wherein, The basic body (10) is provided with a fastening section (11) for vehicle-side fastening of the brake disc (1) and a friction section (12) having at least one friction surface (31), wherein the friction surface (31) is used to abut against the brake pad in the assembly position of the brake disc (1), wherein the friction section (12) has a first structural layer (20) formed of stainless steel and a second structural layer (30) formed of a composite material of an iron alloy matrix and embedded hard particles, characterized in that the second structural layer (30) has a continuous radial surface extension (F) which is smaller than the continuous radial surface extension (F) of the first structural layer (20).

2. The brake disc (1) according to the preceding claim, characterized in that, The second structural layer (30) has a smaller radially outer surface extension (F) than the first structural layer (20).

3. The brake disc (1) according to any one of the preceding claims, characterized in that, The second structural layer (30) has a smaller radially internal planar extension (F) than the first structural layer (20).

4. The brake disc (1) according to any one of claims 2 or 3, characterized in that, The second structural layer (30) extends in its radial plane extension (F) toward the radial end of the first structural layer (20) up to a maximum of 0.1 mm, or toward the radial chamfered convergence (16) of the first structural layer (20) up to a maximum of 0.1 mm.

5. A method for manufacturing a brake disc (1) according to any one of the preceding claims, comprising the following steps: - Provide a basic body (10) made of gray cast iron or steel, said basic body having at least a fastening section (11) and a friction section (12), - A first structural layer (20) made of stainless steel is applied to at least the friction section (12) of the basic body (10) by laser cladding welding. - The second structural layer (30) is applied to the first structural layer (20) by laser cladding welding, wherein, The second structural layer (30) consists of an iron alloy matrix and embedded hard particles. Its characteristics are as follows: - The second structural layer (30) is applied to the first structural layer (20) such that the second structural layer (30) is smaller than the first structural layer (20) in its radial extension (F).

6. The method according to the preceding claims, characterized in that, When the second structural layer (30) is applied to the first structural layer (20), a radial distance is left relative to both the radially outer edge and the radially inner edge of the first structural layer (20).

7. The method according to any one of claims 5 and 6, characterized in that, The brake disc (1) is subjected to subsequent processing in the following areas, wherein the first structural layer (20) is not covered by the second structural layer (30) and therein hard particles are attached.

8. A motor vehicle (K), characterized in that... At least one brake disc (1) according to any one of claims 1 to 4.

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