Brake Disk and Method for Producing Same

Abstract

The invention relates to a brake disk (3), which has at least one thermal conduction layer (4, 6) with a thermal conductivity and specific thermal resistivity that can be graduated, the thermal conduction layer consisting of at least two different materials or of a varying layer thickness, thereby graduating the thermal conductivity or the thermal resistivity within the thermal conduction layer.

Claims

1. A brake disk, comprising a metallic main body (1), which has at least one ring-shaped securing element (12) for securing of the brake disk on a rotating axis (14), a first friction region (2) that faces a rotating axis (14) and takes the form of a circular surface, and a second friction region (3) arranged so as to be diametrically opposite the first friction region (2) and remote from a rotating axis, wherein the metallic main body (1), in the region of the first and second friction regions (2, 3), has at least one ring-shaped heat conduction layer (4, 6) atop which is disposed at least one tribologically stressable hard material layer (8), wherein the at least one heat conduction layer (4, 6) is disposed atop the metallic main body (1) and the tribologically stressable hard material layer (8) atop the heat conduction layer (4, 6) by means of laser buildup welding, so as to achieve a cohesive bond between the layers, wherein the heat conduction layer (4, 6) consists of at least two different materials and the thermal conductivity λ within the heat conduction layer (4, 6) is gradated, wherein there is a metallic or ceramic material and/or a metallic alloy having a thermal conductivity λ.sub.1 at least in an inner circumferential region (9) of the first and/or second friction regions (2, 3), and wherein there is a metallic or ceramic material and/or a metallic alloy having a thermal conductivity λ.sub.2 in an outer circumferential region (11) of the first and/or second friction regions (2, 3), wherein at least λ.sub.1<λ<λ.sub.2.

2. A brake disk, comprising a metallic main body (1), which has at least one ring-shaped securing element (12) for securing of the brake disk on a rotating axis (14), a first friction region (2) that faces a rotating axis and takes the form of a circular surface, and a second friction region (3) arranged so as to be diametrically opposite the first friction region (2) and remote from a rotating axis (14), wherein the metallic main body (1), in the region of the first and/or second friction regions (2, 3), has at least one ring-shaped heat conduction layer (4, 6) atop which is disposed at least one tribologically stressable hard material layer (8), wherein the at least one heat conduction layer (4, 6) is disposed atop the metallic main body (1) and the tribologically stressable hard material layer (8) atop the heat conduction layer (4, 6) by means of laser buildup welding, so as to achieve a cohesive bond between the layers, and wherein at least one of the heat conduction layers (4, 6), in radial direction relative to the outer circumference of the brake disk, has a gradated layer thickness d.sub.SW, as a result of which the specific heat resistance R.sub.thi decreases in the heat conduction layer (4, 6) in radial direction toward the outer circumference of the brake disk.

3. The brake disk as claimed in claim 1, in which there is an arrangement of at least two heat conduction layers, wherein a first heat conduction layer is disposed atop the metallic main body and a second heat conduction layer atop the first heat conduction layer, wherein the at least second heat conduction layer in each case forms an interfacial region with the tribologically stressable hard material layer and with the first heat conduction layer.

4. The brake disk as claimed in claim 1, in which the at least one heat conduction layer and/or tribologically stressable hard material layer on the friction region facing a rotating axis is formed with different layer thickness compared to the at least one heat conduction layer and/or stressable hard material layer on the friction region remote from a rotating axis.

5. The brake disk as claimed in claim 1, in which, in radial direction toward the outer circumference of the brake disk, there is at least one heat conduction layer in an inner circumferential region that extends up to a maximum of 40% of the circumferential area, a material having a thermal conductivity λ.sub.1 of 10 W/(m.Math.K) to 14 W/(m.Math.K), in a middle circumferential region that extends from 30% to a maximum of 65% of the circumferential area a material having a thermal conductivity λ.sub.2 of 12 W/(m.Math.K) to 26 W/(m.Math.K), and in an outer circumferential region that extends from 60% up to the outer circumference of the circumferential area a material having a thermal conductivity λ.sub.3 of 24 W/(m.Math.K) to 40 W/(m.Math.K).

6. The brake disk as claimed in claim 1, in which at least one heat conduction layer has a layer thickness d.sub.SW that increases continuously or abruptly in radial direction toward the outer circumference of the brake disk.

7. The brake disk as claimed in claim 1, in which at least one heat conduction layer has a layer thickness d.sub.SWi of 50 μm to 500 μm, particularly advantageously a layer thickness d.sub.SWi of 100 μm to 150 μm.

8. The brake disk as claimed in claim 1, in which, in radial direction toward the outer circumference of the brake disk, the heat conduction layer has a 10%-15% greater layer thickness d.sub.SW1 in an inner circumferential region that extends up to a maximum of 40% of the circumferential area and, in a middle circumferential region that extends from 30% to a maximum of 65% of the circumferential area, a 5%-10% greater layer thickness d.sub.SW2 compared to the layer thickness d.sub.SW3 in an outer circumferential region that extends from 60% of the circumferential area to the outer circumference, wherein the layer composition composed of heat conduction layer and tribologically stressable hard material layer is constant.

9. The brake disk as claimed in claim 1, in which the heat conduction layer has been produced from an Al-based, Fe-based, Ni-based, Cr-based and/or Cu-based alloy.

10. The brake disk as claimed in claim 1, in which the at least one heat conduction layer additionally includes carbidic and/or oxide ceramic hard material particles.

11. The brake disk as claimed in claim 10, in which the hard material particles of the heat conduction layer have a median particle size D.sub.50 of 0.5 μm to 120 μm.

12. The brake disk as claimed in claim 10, in which the proportion by volume of the hard material particles in the heat conduction layer is 1% to 80%, particularly advantageously 30% to 50%.

13. The brake disk as claimed in claim 1, in which the heat conduction layer takes the form of an alloy in which, in axial direction, the lowest thermal conductivity is in a radial part-region and in the interfacial region with the tribologically stressable hard substance layer, and the highest thermal conductivity in the interfacial region with a further heat conduction layer or the metallic main body.

14. The brake disk as claimed in claim 1, in which there is a bonding layer at least between the metallic main body and the at least first heat conduction layer.

15. The brake disk as claimed in claim 1, in which the tribologically stressable hard material layer has at least a layer thickness d.sub.SH of 50 μm to 500 μm, particularly advantageously a layer thickness d.sub.SH of 200 μm to 250 μm.

16. The brake disk as claimed in claim 1, in which the tribologically stressable hard material layer consists of a cermet, particularly advantageously of silicon carbide, boron carbide, tungsten carbide, vanadium carbide, titanium carbide, tantalum carbide, chromium carbide and/or an oxide ceramic, and very particularly advantageously of tungsten carbide with a stainless steel matrix of material group 4 or 5 with an Ni content of ≤15% by mass.

17. A method of producing the brake disk as claimed in claim 1, in which a first heat conduction layer (4, 6) is disposed in a cohesively bonded manner at least partly at least atop a metallic main body (1) by means of laser buildup welding, and then a tribologically stressable hard material layer (8) is disposed in a cohesively bonded manner atop the first heat conduction layer (4, 6), wherein the heat conduction layer (4, 6) is disposed of at least two different materials and the thermal conductivity λ.sub.i within the heat conduction layer is gradated, such that the heat conduction layer has increasing thermal conductivity λ in radial direction, wherein a metallic or ceramic material and/or a metallic alloy having a thermal conductivity λ.sub.1 is disposed at least in an inner circumferential region (9) of the first and/or second friction regions (2, 3) and a metallic or ceramic material and/or a metallic alloy having a thermal conductivity λ.sub.2 is disposed in an outer circumferential region (11) of the first and/or second friction regions (2, 3), and the surface of the tribologically stressable hard material layer (8) is finally processed.

18. A method of producing the brake disk as claimed in claim 1, in which a first heat conduction layer (4, 6) is disposed in a cohesively bonded manner at least partly at least atop a metallic main body (1) by means of laser buildup welding, and then a tribologically stressable hard material layer (8) is disposed in a cohesively bonded manner atop the first heat conduction layer (4, 6), so as to achieve a cohesive bond between the layers (4, 6, 8), wherein at least one heat conduction layer (4, 6), in radial direction relative to the outer circumference of the brake disk, is disposed with gradated layer thickness d.sub.SW, as a result of which the specific heat resistance R.sub.thi decreases in the heat conduction layer (4, 6) in radial direction toward the outer circumference of the brake disk.

19. The method as claimed in claim 18, in which, in a first step, in radial direction, the heat conduction layer is disposed in an inner circumferential region that extends up to a maximum of 35% of the circumferential area with a 10%-15% greater layer thickness d.sub.S1, and in an inner circumferential region that extends from 30% to a maximum of 65% of the circumferential area with a 5%-10% greater layer thickness d.sub.S2 compared to the layer thickness d.sub.S3 in an outer circumferential region that extends from 60% of the circumferential area to the outer circumference of the brake disk, such that the specific heat resistance R.sub.thi decreases in a gradated manner in the heat conduction layer from the inner circumferential region to the outer circumferential region.

20. The method as claimed in claim 17, in which, in radial direction toward the outer circumference of the brake disk, at least one heat conduction layer is disposed in an inner circumferential region that extends up to a maximum of 35% of the circumferential area, a material having a thermal conductivity λ.sub.1 of 10 W/(m.Math.K) to 14 W/(m.Math.K), in a middle circumferential region that extends from 30% to a maximum of 65% of the circumferential area a material having a thermal conductivity λ.sub.2 of 12 W/(m.Math.K) to 26 W/(m.Math.K), and in an outer circumferential region that extends from 60% up to the outer circumference of the circumferential area a material having a thermal conductivity λ.sub.3 of 24 W/(m.Math.K) to 40 W/(m.Math.K).

21. The method as claimed in claim 17, in which, before the heat conduction layer is disposed by means of laser buildup welding, the metallic main body is heated at least in a subregion of the first and/or second friction regions to a temperature of 150° C. to 500° C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0077] The figures show:

[0078] FIG. 1 a schematic cross section through a brake disk,

[0079] FIG. 2 a detail of the first and second friction regions,

[0080] FIG. 3 a schematic diagram of the coating of a brake disk with constant layer thickness and gradated material composition of the heat conduction layer and tribologically stressable hard material layer,

[0081] FIG. 4 an axial top view of a brake disk with inner, middle and outer circumferential region with gradated heat conduction layer,

[0082] FIG. 5 a schematic layer construction with gradated layer thickness of the heat conduction layer and tribologically stressable hard material layer,

[0083] FIG. 6 a schematic layer construction with a combination of gradated layer thickness of the heat conduction layer and gradated material composition of the heat conduction layer and tribologically stressable hard material layer and

[0084] FIG. 7 a schematic layer construction with 2 gradated heat conduction layers one on top of another.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Working Example 1

[0085] FIG. 1 and FIG. 2 shows a schematic of a cross section through a brake disk with a metallic main body 1 made of gray iron, a securing element 12 and heat conduction layers 4, 6 that are disposed on either side and diametrically on the metallic main body 1, and a tribologically stressable hard material layer 8.

[0086] The first heat conduction layer 4 facing a rotating axis 14 (FIG. 3) consists of an Fe-based alloy, and the first heat conduction layer 6 remote from a rotating axis 14 consists of an Ni-based alloy, wherein the heat conduction layers 4 and 6 are disposed on the metallic main body 1 made of gray iron by means of laser buildup welding.

[0087] Disposed atop each heat conduction layer 4 and 6 is a tribologically stressable hard material layer 8 made of tungsten carbide with a stainless steel matrix of materials number DIN EN 1.4016 (430L) with an average layer thickness of 120 μm, having a thermal conductivity λ of 78 W/(m.Math.K).

[0088] FIG. 4 shows a top view of the brake disk, wherein the brake disk has two diametric heat conduction layers 4 and 6, namely a first heat conduction layer 4 facing a rotating axis and a heat conduction layer 6 remote from a rotating axis 14.

[0089] The first heat conduction layer 4 facing a rotating axis 14 has a total of three circumferential regions 9, 10 and 11 comprising different materials in radial direction. The first material of this heat conduction layer 4 in radial direction has a thermal conductivity λ.sub.1 of 10 W/(m.Math.K) in an inner circumferential region 9 comprising 35% of the circumferential area of the friction region, the second material in radial direction has a thermal conductivity λ.sub.2 of 25 W/(m.Math.K) in a middle circumferential region 10 comprising 35% to 60% of the circumferential area of the friction region, and the third material in radial direction has a thermal conductivity λ.sub.3 of 55 W/(m.Math.K) in an outer circumferential region 11 comprising 60% up to the outer circumference of the circumferential area of the friction region.

[0090] The heat conduction layer 6 remote from the rotating axis 14 likewise has, in radial direction, a total of three circumferential regions 9, 10 and 11 comprising different materials. The first material of the heat conduction layer 6 remote from a rotating axis 14 in radial direction has a thermal conductivity λ.sub.1 of 12 W/(m.Math.K) in an inner circumferential region 9 comprising 30% of the circumferential area of the friction region, the second material in radial direction has a thermal conductivity λ.sub.2 of 23 W/(m.Math.K) in a middle circumferential region 10 comprising 30% to 45% of the circumferential area of the friction region, and the third material in radial direction has a thermal conductivity λ.sub.3 of 48 W/(m.Math.K) in an outer circumferential region 11 comprising 45% up to the outer circumference of the circumferential area of the friction region.

[0091] The first heat conduction layer 4 facing a rotating axis 14, as shown in FIGS. 3 and 6, in radial direction, has a constantly decreasing layer thickness d.sub.SW, where the smallest layer thickness d.sub.SW3 is at the outer circumference of the friction region at 90 μm, and the greatest layer thickness d.sub.SW4 at the inner circumference of the friction region at 145 μm.

[0092] The heat conduction layer 6 remote from a rotating axis 14 has, as shown in FIGS. 3 and 6, in radial direction, a constant layer thickness d.sub.SW of 120 μm.

[0093] The arrangement of heat conduction layers 4 and 6 enables a homogeneous heat budget in the tribologically stressable hard material layer 8 with which faster thermal readiness for use is enabled over the entire circumferential area of the friction regions 2 and 3. Moreover, the gradated heat conduction layers 4 and 6 and the different layer thicknesses prevent the occurrence of the shielding effect, which prevents formation of cracks in the brake disk.

Working Example 2

[0094] FIG. 1 and FIG. 2 show a schematic of a cross section through a brake disk with a metallic main body 1 made of gray iron, a securing element 12 and a heat conduction layers 4, 6 that are disposed on either side and diametrically on the metallic main body, and a tribologically stressable hard material layer 8.

[0095] The first heat conduction layer 4 facing a rotating axis 14 (FIG. 3) consists of a Cr-based alloy, and the heat conduction layer remote from a rotating axis 14 consists of a Cu-based alloy, wherein the heat conduction layers 4 and 6 are disposed on the metallic main body 1 made of gray iron by means of laser buildup welding.

[0096] Disposed atop each heat conduction layer 4 and 6 is a tribologically stressable hard material layer 8 made of tungsten carbide with a stainless steel matrix of materials number DIN EN 1.4016 (430L) with an average layer thickness of 120 μm, having a thermal conductivity λ of 78 W/(m.Math.K).

[0097] FIG. 4 shows a top view of the brake disk, wherein the brake disk has two diametric heat conduction layers, namely a heat conduction layer 4, 6 facing a rotating axis 14 and one remote from a rotating axis 14.

[0098] The heat conduction layer 4 facing a rotating axis 14 has a total of three regions 9, 10 and 11 comprising different materials in radial direction. The first material of this heat conduction layer 4 in radial direction has a thermal conductivity λ.sub.1 of 12 W/(m.Math.K) in an inner circumferential region 9 comprising 30% of the circumferential area of the friction region, the second material of the heat conduction layer in radial direction has a thermal conductivity λ.sub.2 of 23 W/(m.Math.K) in a middle circumferential region 10 comprising 40% of the circumferential area of the friction region, and the third material of the heat conduction layer in radial direction has a thermal conductivity λ.sub.3 of 36 W/(m.Math.K) in an outer circumferential region 11 comprising 30% of the circumferential area of the friction region.

[0099] The heat conduction layer 6 remote from a rotating axis 14 has, in radial direction, a total of three regions 9, 10 and 11 comprising different materials. The first material of this heat conduction layer in radial direction has a thermal conductivity λ.sub.1 of 12 W/(m.Math.K) in an inner circumferential region 9 comprising 30% of the circumferential area of the friction region, the second material of the heat conduction layer in radial direction has a thermal conductivity λ.sub.2 of 23 W/(m.Math.K) in a middle circumferential region comprising 40% of the circumferential area of the friction region, and the third material of the heat conduction layer in radial direction has a thermal conductivity λ.sub.3 of 36 W/(m.Math.K) in an outer circumferential region 11 comprising 30% of the circumferential area of the friction region.

[0100] The heat conduction layer 6 remote from a rotating axis 14 and the heat conduction layer 4 facing a rotating axis 14, according to FIG. 5, have a constantly decreasing layer thickness d.sub.SW in radial direction, where the smallest layer thickness d.sub.SW1 and d.sub.SW3 is at the outer circumference of the friction region at 80 μm, and the greatest layer thickness d.sub.SW2 and d.sub.SW4 is at the inner circumference of the friction region at 160 μm.

[0101] The arrangement of heat conduction layers 4 and 6 enables a homogeneous heat budget in the tribologically stressable hard material layer 8 with which faster thermal readiness for use is enabled over the entire circumferential area of the friction regions 2 and 3. Moreover, the gradated heat conduction layers 4 and 6 and the different layer thicknesses prevent the occurrence of the shielding effect, which prevents formation of cracks in the brake disk.

Working Example 3

[0102] FIG. 7 shows a first friction region 2 or second friction region 3, in which two different heat conduction layers 4 and 5 and a tribologically stressable hard material layer 8 are disposed on the metallic main body 1.

[0103] The heat conduction layer 5 consists of an Al-based alloy without grading, and is disposed atop the metallic main body 1. The heat conduction layer 4 is disposed atop the heat conduction layer 5 and consists of a Cu-based alloy.

[0104] The heat conduction layer 5 has, in radial direction, a total of three regions 9, 10 and 11 comprising different materials. The first material of this heat conduction layer in radial direction has a thermal conductivity λ.sub.1 of 12 W/(m.Math.K) in an inner circumferential region 9 comprising 30% of the circumferential area of the friction region, the second material of the heat conduction layer has a thermal conductivity λ.sub.2 of 23 W/(m.Math.K) in radial direction in a middle circumferential region 10 comprising 40% of the circumferential area of the friction region, and the third material of the heat conduction layer has a thermal conductivity λ.sub.3 of 36 W/(m.Math.K) in radial direction in an outer circumferential region 11 comprising 30% of the circumferential area of the friction region.

[0105] The heat conduction layer 5 has a constant layer height in radial direction with an averaged thickness d.sub.SW of 120 μm.

[0106] The arrangement of heat conduction layers 4 and 5 enables a homogeneous heat budget in the tribologically stressable hard material layer 1 with which faster thermal readiness for use is enabled over the entire circumferential area of the friction regions 2 and 3. Moreover, the gradated heat conduction layers 4 and 5 and the different layer thicknesses prevent the occurrence of the shielding effect, which prevents formation of cracks in the brake disk.

LIST OF REFERENCE NUMERALS

[0107] 1—metallic main body

[0108] 2—first friction region facing a rotating axis

[0109] 3—second friction region remote from a rotating axis

[0110] 4—first heat conduction layer facing a rotating axis

[0111] 5—second heat conduction layer facing a rotating axis

[0112] 6—first heat conduction layer remote from a rotating axis

[0113] 7—second heat conduction layer remote from a rotating axis

[0114] 8—tribologically stressable hard material layer

[0115] 9—inner circumferential region

[0116] 10—middle circumferential region

[0117] 11—outer circumferential region

[0118] 12—securing element

[0119] 13—ventilation ducts

[0120] 14—rotation axis