Brake drum for a drum brake, method for manufacturing a brake drum and use of the brake drum in a drum brake

Abstract

The invention relates to a brake drum for a drum brake, having a first element comprising a first metallic material and a second element comprising a second metallic material, wherein the first element is connected to the second element by means of a casting technique. The brake drum further has an adhesive layer, wherein the adhesive layer is located between the first element and the second element, and wherein the first element and the second element are connected in a material-locked manner by means of intermetallic bonding by means of the adhesive layer. Furthermore, the invention also relates to a method for producing the brake drum and to the use thereof.

Description

Technical Field

[0001] The present invention relates to a brake drum for a drum brake having a first element comprising a first metallic material and a second element comprising a second metallic material, wherein the two elements are connected to each other in a material-locking manner by intermetallic bonding, and also relates to a method for manufacturing the brake drum and the application of the brake drum in a drum brake of the class according to the independent claim. Background Technology

[0002] Brake drums for drum brakes are typically designed in the form of an inner ring, which is made of cast iron or cast steel, for example, to provide sufficient stability, and especially for weight reduction and to ensure good heat dissipation, is embedded within an outer ring, which is typically made of a relatively lightweight alloy (e.g., an aluminum-based alloy). To prevent the inner ring from detaching from the outer ring and potentially moving within it, ultimately leading to loss of braking effect, mechanical bonding is currently used between the two rings according to the prior art. This can be achieved, for example, by giving the inner ring a rough surface facing the outer ring, and particularly by having multiple side recesses. Alternatively, this surface may also have multiple protrusions, for example. For example, EP 2497967 B1 relates to a brake drum in which an inner ring made of cast iron, cast steel, or aluminum alloy is present within an outer ring made of an aluminum or magnesium alloy. The outer ring is applied by die casting. The inner ring has protrusions on its outward-facing surface, these protrusions having a waisted shape, thus enabling mechanical bonding. Summary of the Invention

[0003] The objective of this invention is to provide an improved or at least alternative embodiment of the brake drum. In particular, the objective of this invention is to describe an embodiment of the brake drum that enables improved load-bearing capacity and / or improved heat dissipation of the components.

[0004] This task is solved according to the invention by the subject matter of the independent claim. Advantageous embodiments are the subject matter of the dependent claims.

[0005] According to the present invention, a brake drum for a drum brake is provided, wherein the brake drum has a first element comprising a first metallic material and a second element comprising a second metallic material, wherein the first element and the second element are connected by a casting technique, wherein the first element has a rough surface oriented toward the second element, and wherein the brake drum further has an adhesive layer, wherein the adhesive layer is located between the first element and the second element, and the first element and the second element are connected by intermetallic bonding via the adhesive layer in a material-locking manner.

[0006] The main advantage of the brake drum according to the invention, which has the features of independent claim 1, over the prior art is that it provides a particularly good bond between the inner and outer rings.

[0007] Another major advantage of the brake drum according to the invention is that the components have a higher load-bearing capacity, for example, even under alternating thermal loads. Furthermore, the brake drum according to the invention also achieves excellent heat dissipation.

[0008] Furthermore, the main advantage of this invention is that it prevents the formation of gaps between the two components, can absorb combined stress, and allows the force acting on the brake drum to be transmitted well without damaging the brake drum.

[0009] Furthermore, in addition to die casting, this invention can also utilize other casting methods. Therefore, this invention can also utilize mold casting, which can achieve a particularly dense casting structure.

[0010] This is achieved in particular by providing an adhesive layer, in addition to a rough surface of the first element containing the first metallic material oriented toward the second element containing the second metallic material, for connecting the first element and the second element in a material-locking manner by means of intermetallic bonding.

[0011] The following describes in more detail the brake drum for a drum brake according to the invention, the method for manufacturing the brake drum, and the application of the brake drum, wherein the drawings used in this regard within the framework of the description of the brake drum according to the invention are equally applicable to the method and application, and vice versa.

[0012] This invention is based on the general concept of a brake drum having a first element comprising a first metallic material and a second element comprising a second metallic material. The first and second elements are joined by a casting technique. The first element has a rough surface oriented toward the second element. For example, the first element is designed as a hollow cylinder with a rough surface on its outer side pointing toward the second element. The second element is also designed as a hollow cylinder and surrounds the first element. To effectively connect the first and second elements, the brake drum also has an adhesive layer located between the first and second elements. For example, the adhesive layer can be first applied to the outwardly oriented rough surface of the first element, and then the first element can be cast in a mold with a liquid second metallic material. The second element is formed by the cooling and solidification of the second metallic material, and then the second element is firmly connected to the first element.

[0013] Alternatively, one could conceive of providing a brake drum having a first element made of a first metallic material and a second element made of a second metallic material.

[0014] For example, one could conceive of an outer diameter of the second element ranging from a minimum of approximately 60 mm to a maximum of approximately 400 mm. Furthermore, one could conceive of an inner diameter of the first element ranging from a minimum of approximately 30 mm to a maximum of approximately 370 mm. It should be understood that this depends on the type of vehicle and, in particular, the size of the wheel on which the brake drum is to be applied.

[0015] In order to enable a first element comprising a first metallic material to be cast and encased in a mold in solid form by a second metallic material without altering its shape, it has proven advantageous that the melting temperature of the first metallic material is higher than that of the second metallic material. Preferably, the melting temperature of the first metallic material is at least 300°C higher than that of the second metallic material.

[0016] It has proven advantageous that the first metallic material comprises Fe, and the second metallic material comprises at least one element selected from the group consisting of Al and Mg. Preferably, the first metallic material comprises at least 90% by weight of Fe, and the second metallic material comprises at least 75% by weight of at least one element selected from the group consisting of Al and Mg. Alternatively, the first metallic material advantageously comprises Fe, preferably at least 90% by weight of Fe. Alternatively, the second metallic material advantageously comprises at least one element selected from the group consisting of Al and Mg, preferably at least 75% by weight of at least one element selected from the group consisting of Al and Mg.

[0017] Particularly preferred is that the first metallic material comprises at least 90% by weight Fe, and the second metallic material comprises at least 85% by weight of at least one element selected from the group consisting of Al and Mg. Alternatively, the second metallic material particularly preferably comprises at least 85% by weight of at least one element selected from the group consisting of Al and Mg.

[0018] For example, this might mean that the first metallic material is made of cast iron or cast steel. Cast iron, as understood by those skilled in the art, is an iron-based material with a high carbon content, typically exceeding 2% by mass. Gray cast iron can be distinguished here, in which carbon is embedded in the form of graphite. Conversely, white cast iron contains carbon embedded in the form of carbides (cementite Fe3C). Both types of cast iron, namely gray cast iron and white cast iron, can be used in principle. Within the framework of this invention, cast steel is understood to be all steel grades that can be cast into their final shape in molten form. For example, the first metallic material could be cast iron of the GJL grade according to DIN-EN-1561:2012-01, such as cast iron of the EN-GJL-200 grade. This is a cast iron containing flake graphite.

[0019] Furthermore, this means, for example, that the second metallic material is composed of an aluminum alloy or a magnesium alloy. An aluminum alloy is an alloy in which aluminum is used as the base material and other alloying elements are added to the aluminum, thereby affecting the material properties of the resulting alloy. For example, but not limited to, such alloying elements in aluminum alloys include Cu, Mg, Zn, Si, and Mn. Therefore, those skilled in the art know that the main component of an aluminum alloy is aluminum, and the sum of all components is 100% by weight. In a sense, a magnesium alloy is an alloy in which magnesium is used as the base material and other alloying elements are added to the magnesium. For example, but not limited to, such alloying elements in magnesium alloys include Cu, Zn, Si, Mn, and Zr. In this regard, "at least 75% by weight of at least one element selected from the group consisting of Al and Mg" further means that the alloy either contains at least 75% by weight of Al, or the alloy contains at least 75% by weight of Mg, or the sum of Al and Mg contained in the alloy is at least 75% by weight. Additionally, other alloying elements may also be present. It should be understood that the sum of all components contained must each be 100% by weight. In addition, one could also think of a second metallic material, such as an aluminum alloy in which magnesium is added as one of the alloying elements.

[0020] For example, the second metallic material could be EN AW-4032 alloy (forged alloy). According to the European standard (DIN EN573-3:2009), forged aluminum alloys are designated EN AW followed by four digits, where these digits represent their composition. For example, ENAW-4032 is a representative of the ENAW-4000 grade. This grade is often alternatively designated, for example, as EN AW-4xxx. Cast aluminum alloys are also conceivable. According to the European standard (DIN EN 1706:2021), such cast aluminum alloys are designated EN AC followed by five digits, where these digits again represent their composition. An example of a cast aluminum alloy is EN AC 43300.

[0021] Chemical composition can be determined using chemical analysis methods, such as inductively coupled plasma atomic emission spectrometry. This also applies to the chemical composition of other components or layers described below.

[0022] In principle, all casting methods known to those skilled in the art, such as sand casting, centrifugal casting, metal mold casting, or die casting, are suitable for manufacturing a first element comprising a first metallic material. It has proven particularly suitable that the first element is made by means of centrifugal casting.

[0023] Furthermore, it has proven advantageous that the first metallic material is made of gray cast iron. This results in exceptionally good compressive strength, good damping characteristics, and good corrosion resistance. In addition, it enables high economic efficiency.

[0024] Furthermore, it has proven particularly advantageous that the first metallic material is made of gray cast iron and the second metallic material is made of aluminum alloy.

[0025] Furthermore, in an advantageous improvement of the invention, it has also proven advantageous that the roughness profile R of the surface of the first element facing the second element is... t The overall height is at least 500 μm and at most 1200 μm.

[0026] According to DIN EN ISO 4287:2010, the roughness profile R t The overall height (also known as the maximum roughness depth) is understood as the height Z of the maximum profile peak within the measurement section. p With the depth Z of the largest contour valley v The sum. Typically, the roughness profile R t The overall height is typically determined by scanning the surface over a defined measurement section and recording all height and depth variations. Regarding the roughness profile R... t For a detailed description of the overall height, please refer to DIN EN ISO4287:2010.

[0027] The overall height of the aforementioned roughness profile can be achieved, for example, by means of a refractory coating on the mold. Advantageously, such a refractory coating is highly porous in its dry state. For example, a silicate coating with a high melting point is conceivable. If a liquid material is fed into the mold, it partially enters the pores of the refractory coating, subsequently generating the rough surface of the resulting component upon cooling. Similarly, it is conceivable, for example, that the walls of the mold are internally covered with particles composed of refractory material, which are removed from the component after casting. For example, these particles may contain spheroidal graphite. Any residue of the refractory coating or refractory particles that may adhere to the component can be removed by cleaning methods, such as by blasting. For example, residues of the refractory coating or refractory particles adhering to the component can be removed by light sandblasting or light blasting with hard cast steel grit. It should be understood that while the blasting intensity is sufficient to remove residues of the refractory coating or refractory particles, it does not substantially alter the rough surface structure of the component. This, for example, means that after cleaning, the roughness profile R of the surface of the first element facing the second element... t The overall height is preferably at least 500 μm and at most 1200 μm. Furthermore, the edges of the ring are deburred as needed.

[0028] Furthermore, it has proven advantageous that the roughened surface of the first element oriented toward the second element has a side recess, wherein the roughened surface of the first element oriented toward the second element preferably has at least about 0.36 mm in the 25 mm segment L. 10 5 μm 2 And the maximum is approximately 30 10 5 μm 2 The area of ​​the concave part A UC .

[0029] Area A of the concave side UC The measurement of the "Undercut area" can be performed, for example, as follows: First, a cross-sectional polished disc of the specimen to be tested is prepared and observed using an optical camera. Within the rough surface region of the specimen, a 25 mm long segment (L) is selected with respect to the inner diameter ID [mm] of the ring to be tested. Then, within this segment L [mm], the reference diameter GD [mm] and outer diameter OD [mm] are determined, where the reference diameter GD corresponds to the baseline of the rough surface region, and the outer diameter OD corresponds to the envelope of the rough surface region. However, to obtain reproducible results, the deepest profile valleys and the highest profile peaks are pre-filtered out. This is achieved by identifying the minimum height and minimum spacing of the profile peaks and valleys that still need to be considered for evaluation. To this end, a reference area A0 is first determined based on the initial value OD0 of the inner diameter ID and outer diameter OD (which initially still contains all profile peaks). Then, the outer diameter OD is moved towards the inner diameter ID until the summed cross-sectional area of ​​the detected specimen is 90% of the reference area A0.

[0030] Subsequently, the sample image along the originally curved section L is flattened, and the areas (A1, A2, ..., A1) constituting the side concavity are determined using a vertical line from the inner diameter ID to the outer diameter OD. n The areas identified in this way are then summed.

[0031]

[0032] Typically, this measurement is performed three times at different locations on the surface, and the resulting area A is... UC Divide by the number of measurements.

[0033] Furthermore, it has proven advantageous that the thickness of the adhesive layer ranges from a minimum of about 10 μm to a maximum of about 500 μm, preferably from a minimum of about 40 μm to a maximum of about 200 μm. The thickness measurement is performed perpendicular to the surface of the first element. Thickness measurement can be performed using a metallographic grinding wheel, wherein the thickness of layers down to a minimum of about 1 μm can be determined using optical microscopy. Alternatively, analysis can be performed using a scanning electron microscope.

[0034] The adhesive layer may, for example, have at least one layer containing at least one element or alloy selected from the group consisting of Sn, Al, Zn, Si, Fe, Al5Fe2, Sn-Al alloy, Zn-Al alloy, Al-Si alloy, Sn-Fe alloy, Sn-Al-Fe alloy, Zn-Al-Fe alloy, Al-Si-Fe alloy, Al-Fe alloy, Al-Si-Mg alloy, and Al-Mg alloy. For example, in the context of the adhesive layer, "Al-Fe alloy" means that the alloy contains Al and Fe as major components, wherein it is conceivable that the alloy has a higher proportion of Al (by weight percentage) than Fe, and also that the alloy has a higher proportion of Fe (by weight percentage) than Al. In particular, it is conceivable that the Fe content decreases from the surface of the first element to the surface of the second element, while the Al content increases accordingly.

[0035] Within the framework of this invention, the term "alloy" may also include so-called "intermetallic compounds." The terms "alloy" and "intermetallic compound" are known to those skilled in the art. Thus, an "alloy" is understood as a macroscopically homogeneous material composed of at least two components, at least one of which is a metal. It can form a solid solution or multiple phases. An intermetallic compound (also referred to as an intermetallic phase) is understood as a homogeneous chemical compound with a lattice structure different from that of the involved metals, composed of two or more metals. Typically, bonding within an intermetallic compound includes both metallic bonding portions and small amounts of covalent and / or ionic bonds. It is conceivable that an intermetallic compound has a stoichiometric composition of the involved metals, and that the phase has a homogeneous range (phase width) in the phase diagram within which the proportion of the involved metals can vary.

[0036] For cases where the adhesive layer has an alloy containing Sn or Zn as its main component, it has also proven advantageous to deposit a layer, for example, a chromium-containing layer, on the surface of the first element beforehand, for example by electroplating. In this regard, the terms "electroplating," "electrolytic deposition," or "coating" are understood to refer to a deposition reaction that occurs on the surface to be coated, forced by an introduced current.

[0037] Furthermore, it has proven advantageous that the adhesive layer has at least one intermetallic layer and at least one impregnation layer, wherein the at least one intermetallic layer is located on the surface of the first element oriented toward the second element, and wherein the at least one impregnation layer is located on the at least one intermetallic layer and oriented toward the second element.

[0038] Furthermore, it has proven advantageous that the thickness of at least one intermetallic layer is at least about 1 μm and at most about 50 μm. It has also proven advantageous that the thickness of at least one impregnated layer is at least about 9 μm and at most about 450 μm. It should be understood that the thickness of the adhesive layer is calculated from the sum of the thickness of at least one intermetallic layer and the thickness of at least one impregnated layer.

[0039] It has proven particularly advantageous that the thickness of at least one intermetallic layer is at least about 4 μm and at most about 30 μm. Furthermore, it has proven particularly advantageous that the thickness of at least one impregnated layer is at least about 36 μm and at most about 170 μm.

[0040] Furthermore, it is preferred that, i) At least one intermetallic layer comprises at least one alloy selected from the group consisting of Al5Fe2, Al-Fe alloys, and Al-Fe-Si alloys, and ii) At least one impregnation layer contains an Al-Si alloy with a Si content ranging from a minimum of about 5% by weight to a maximum of about 20% by weight.

[0041] The preferred alternative is, i) At least one intermetallic layer comprises at least one alloy selected from the group consisting of Al5Fe2, Al-Fe alloys and Al-Fe-Si alloys.

[0042] As another preferred alternative, ii) At least one impregnation layer contains an Al-Si alloy with a Si content ranging from a minimum of about 5% by weight to a maximum of about 20% by weight.

[0043] Furthermore, it is particularly preferred that, i) At least one intermetallic layer comprises at least one alloy selected from the group consisting of Al5Fe2, Al-Fe alloys, and Al-Fe-Si alloys, and ii) At least one impregnation layer contains an Al-Si alloy with a Si content ranging from a minimum of about 9% by weight to a maximum of about 13% by weight.

[0044] As another preferred alternative, ii) At least one impregnation layer contains an Al-Si alloy with a Si content ranging from a minimum of about 9% by weight to a maximum of about 13% by weight.

[0045] All casting methods known to those skilled in the art, such as sand casting, mold casting, or die casting, are generally suitable for manufacturing the second element. However, it has proven advantageous that the second element comprising the second metallic material is a die-cast element. This means that it is advantageous to obtain the second element comprising the second metallic material by die casting. Alternatively, it has proven advantageous that the second element comprising the second metallic material is a mold-cast element. This means that it is advantageous to obtain the second element comprising the second metallic material by mold casting. The advantage of using the mold casting method is particularly that it yields a particularly dense casting structure, which results in particularly good adhesion and stability.

[0046] Furthermore, it has been proven advantageous that the brake drum possesses an average shear strength σ of at least 130 MPa. 剪切,平均 .

[0047] Mean shear strength σ 剪切,平均 The formula is obtained by dividing the average applied force by the area, as follows: σ 剪切,平均 = F / A Preferably, the shear strength is measured (as described in Example IE1 and in...) Figure 4 (As explained in the text) This is done using rings with a width t of approximately 5 mm cut from the brake drum. These cut rings therefore include both an inner ring (composed of a segment of the first element containing the first metal material) and an outer ring (composed of a segment of the second element containing the second metal material). Thus, these specimens can be placed into the press without any problems. Then, the portion of the cut ring composed of the first element containing the first metal material (i.e., the inner ring) is continuously pressed with a pressure head until the specimen either breaks or the press's load limit is reached. It is conceivable that the breakage occurs between the inner and outer rings (i.e., between the corresponding specimen segments of the first element containing the first metal material and the second element containing the second metal material), or it is conceivable that the breakage occurs within the first or second ring.

[0048] Furthermore, it has been proven advantageous that the brake drum possesses an average shear strength σ of at least 110 MPa, measured after being subjected to a thermal load of 450°C for 4 hours. 剪切,平均 .

[0049] This means that before measuring the shear strength, these rings are first heated to approximately 450°C and held at that temperature for about 4 hours. This thermal load is used to simulate the temperature rise of a brake drum during operation, especially during repeated heavy braking. After the thermal load, the rings are placed in the press as described above, and the indenter is used to continuously press the portion of the cut ring consisting of the first element containing the first metallic material (i.e., the inner ring) until the specimen breaks or the press's load limit is reached.

[0050] The present invention also relates to a method for manufacturing a brake drum as described above, the method comprising steps a) to g). a) Providing a first element comprising a first metallic material, wherein the first element has at least partially a rough surface. b) Heating the first element containing the first metallic material. c) Immerse the first element in an impregnation bath, preferably with an impregnation bath temperature of at least about 600°C and at most about 900°C. d) The first element is allowed to remain in the impregnation bath for a duration of at least about 1 minute and at most about 10 minutes. e) Remove the first element from the impregnation tank. f) Place the first element into the mold and close the mold. g) The second element is formed by casting a second metal material over the first element, wherein the first element has a rough surface facing the second element.

[0051] In step a), a first element comprising a first metallic material is first provided. For example, the first element is designed as a hollow cylinder with a roughened surface on its outer side. Advantageously, the first metallic material comprises Fe, and more particularly advantageously, it comprises at least 90% by weight of Fe. For example, the first metallic material is made of cast iron, and more particularly advantageously, of gray cast iron. The first element can be manufactured, for example, by sand casting, centrifugal casting, metal mold casting, or die casting. Advantageously, in a later step g), the roughness profile R of the first element on the side facing the second element is... t The overall height is at least 500 μm and at most 1200 μm.

[0052] Subsequently, in step b), the first element containing the metallic material is heated. Advantageously, the first element is heated to a temperature above the dew point. The term "dew point" is known to those skilled in the art. It refers to the condensation point of water in the air. Therefore, it depends on the air temperature and relative humidity, and can be measured, for example, using a cold mirror dew point meter.

[0053] Following step b), in step c), the first element is immersed in an immersion bath at a temperature preferably between a minimum of about 600°C and a maximum of about 900°C. It should be understood that the choice of immersion bath temperature depends on the material contained in the immersion bath. Therefore, those skilled in the art will naturally understand that the temperature of the immersion bath should be suitably selected to completely melt, for example, the alloy contained in the immersion bath. Furthermore, it must be ensured that the first element is in direct and complete contact with the contents of the immersion bath. Therefore, the immersion should be carried out in such a manner that at least the outward-facing surface of the first element is completely wetted by the immersion bath.

[0054] The impregnation bath is, for example, an impregnation bath containing a melt having at least one element or alloy selected from the group consisting of Al, Sn-Al alloys, Zn-Al alloys, Al-Si alloys, Al-Si-Fe alloys, Al-Si-Mg alloys, Sn-Fe alloys, Sn-Al-Fe alloys, Zn-Al-Fe alloys, or Al-Mg alloys. Preferably, the impregnation bath is an impregnation bath containing a melt containing an element or alloy selected from the group consisting of Al and Al-Si alloys. Particularly preferred is an impregnation bath containing an Al-Si alloy having a Si content of at least about 5% by weight and at most about 20% by weight. It is conceivable that the melt contains additional impurities, such as Fe. Particularly preferred is that the Fe content in the melt is about equal to or less than 3.5% by weight.

[0055] Alternatively, it is conceivable to first deposit a layer, such as a chromium-containing layer, on the first element by electroplating before performing step c). This can improve adhesion, especially when combined with an impregnation bath containing a melt comprising at least one element or alloy selected from the group consisting of Sn-Al alloys and Zn-Al alloys.

[0056] In step d), the first element is subsequently immersed in the immersion bath for a duration of at least about 1 minute and at most about 10 minutes. It is important to ensure that the first element is well wetted by the melt contained in the immersion bath. Particularly preferred is that the first element is immersed in the immersion bath for at least about 2.5 minutes and at most about 6.5 minutes. It has proven advantageous that the treatment in the immersion bath forms an adhesive layer with a thickness of at least about 10 μm and at most about 500 μm, preferably at least about 40 μm and at most about 200 μm. In this respect, it has proven particularly advantageous that the treatment in the immersion bath forms an adhesive layer having at least one intermetallic layer and at least one immersion layer, wherein the at least one intermetallic layer is located on the surface of the first element oriented toward the second element, and wherein the at least one immersion layer is located on the at least one intermetallic layer and oriented toward the second element.

[0057] In the subsequent step e), the first element is removed from the impregnation tank. After removal from the impregnation tank, in step f), the first element is placed into the mold and the mold is closed.

[0058] Then, in step g), the first element is cast and coated with a second metallic material to form the second element. It should be understood that, for this purpose, the second metallic material must be in a molten state. The second metallic material, for example, contains at least one element selected from the group consisting of Al and Mg, preferably at least 75% by weight of at least one element selected from the group consisting of Al and Mg. The casting and coating is performed on the side of the first element whose surface is designed to be rough. For example, the casting and coating is performed such that the second element containing the second metallic material is formed around the first element in the form of a hollow cylinder, wherein the inner side of the hollow cylinder formed by the second element adheres to the outer side of the hollow cylinder formed by the first element, which has a rough surface on the surface pointing towards the second element.

[0059] Of particular advantage is that steps e) to g) are completed within a timeframe of up to approximately 2 minutes. This enables exceptionally good adhesion.

[0060] The second component can be manufactured, for example, by sand casting, metal mold casting, or die casting.

[0061] In an advantageous embodiment, die casting is used to coat the first element with a second metallic material. For example, the pressure during die casting can preferably be a minimum of about 10 bar to a maximum of about 900 bar. This allows the molten second metallic material to penetrate particularly well into the rough surface structure of the first element.

[0062] In another advantageous embodiment, a metal mold casting method is used to cast and encapsulate the first element with a second metallic material. This makes the method particularly easy to apply and particularly economical. Furthermore, a particularly dense microstructure is advantageously obtained. In principle, all metal mold casting methods known to those skilled in the art can be applied. Particularly preferably, a gravity metal mold casting method is used to cast and encapsulate the first element with a second metallic material.

[0063] After the obtained brake drum has cooled, it can be removed from the mold.

[0064] The present invention also relates to the application of brake drums as described above, preferably in drum brakes for motor vehicles or motorized two-wheelers (e.g., passenger vehicles, trucks, motorcycles or electric scooters / electric scooters). Attached Figure Description

[0065] Other important features and advantages of the present invention are derived from the dependent claims, the accompanying drawings and their corresponding descriptions, and the embodiments.

[0066] It should be understood that the features mentioned above and further described below can be used not only in the combinations given separately, but also in other combinations or individually, without departing from the scope of the invention.

[0067] The following are illustrative examples: Figure 1 A perspective view of the brake drum is shown. Figure 2 A flowchart illustrating a method for manufacturing a brake drum is shown. Figure 3 The image shown is an image taken by optical microscopy, which shows a section of the surface of the first element toward the second element including the adhesive layer and a section of the surface of the second element toward the adhesive layer (a), and a magnified section of the surface of the first element toward the second element including the adhesive layer (b). Figure 4 A diagram illustrating a section of the measurement structure used to determine the average shear strength is shown. Figure 5: Shows the method used to determine the area A of the lateral concave portion. UC The method is illustrated in the following diagrams: a) shows the measurement section L, inner diameter ID, reference diameter GD, and outer diameter OD; b) shows the diagram used to interpret the profile filtering; and c) shows the diagram used to identify the various areas constituting the side recess. Detailed Implementation

[0068] Figure 1 An exemplary brake drum 100 is shown, which has a first element 101 comprising a first metallic material, the first element being... Figure 1 The first element 101 is designed as an internal hollow cylinder. The first element 101 is surrounded by a second element 102 containing a second metallic material, and the second element is constructed as an external hollow cylinder. Figure 1The adhesion layer between the first and second elements is not shown. Preferably, the first metallic material contains Fe, particularly at least 90% by weight of Fe. More preferably, the first metallic material is cast iron or cast steel. Preferably, the second metallic material contains at least one element selected from the group consisting of Al and Mg, more preferably at least 75% by weight of at least one element selected from the group consisting of Al and Mg, and particularly preferably at least 85% by weight of at least one element selected from the group consisting of Al and Mg. Preferably, the outer diameter of the second element 102 is from a minimum of about 60 mm to a maximum of about 400 mm. Preferably, the inner diameter of the first element 101 is from a minimum of about 30 mm to a maximum of about 370 mm. It should be understood that the outer diameter of the second element 102 must be larger than the inner diameter of the first element 101. It should also be understood that the specifications of the brake drum depend on the type of vehicle and, in particular, the size of the wheel on which the brake drum is to be applied. For example, in a passenger vehicle, the inner diameter of the first element 101 may be about 270 mm, and the outer diameter of the second element 102 may be about 350 mm. It should be understood that, for example, for heavy-duty vehicles or construction machinery, the size must be chosen accordingly to be larger.

[0069] Figure 2 The process of a method for manufacturing a brake drum is schematically illustrated. Here, firstly in step a), a first element, 200, comprising a first metallic material is provided, wherein the first element at least partially has a rough surface. In a subsequent step b), the first element is heated, 201. Subsequently, in step c), the first element is immersed in an immersion bath, 202, at a temperature preferably from a minimum of about 600°C to a maximum of about 900°C. Optionally, prior to performing step c), a layer, for example a chromium-containing layer, may first be deposited on the first element by electroplating. This is particularly preferred when combined with an immersion bath comprising a melt having at least one alloy selected from the group consisting of Sn-Al alloys and Zn-Al alloys. This optional additional step... Figure 2Not shown in the diagram. In step d), the first element is immersed in the immersion bath for a duration of at least about 1 minute to at most about 10 minutes, 203. Subsequently, in step e), the first element is removed from the immersion bath, 204. Then, in step f), the first element is placed into a mold and the mold is closed, 205. Subsequently, in step g), the first element is cast over it with a second metal material to form the second element, 206. This, of course, means that the second metal material must be in a molten state during casting over it. The second element is obtained by casting over it. As previously described, the first element has a rough surface facing the second element. The casting of the second element can, in principle, be carried out by sand casting, metal mold casting, or die casting. It is particularly advantageous to cast by die casting or metal mold casting. After casting and cooling the second element, the obtained brake drum can be removed from the mold. The foregoing content relating to the method steps applies to all method steps a) to g), unless otherwise described.

[0070] Figure 3 a) Images taken by optical microscopy show a section of the first element facing the surface of the second element, including the adhesive layer, and a section of the second element facing the surface of the adhesive layer. Figure 3 b) shows an enlarged section of the surface of the first element, including the adhesive layer, facing the second element. Figure 3 a) and Figure 3 Section b) shows a section of the first element 300, which, currently, is a blank casting ring made of Ni-Resist alloy. An adhesion layer 301 is present on the surface of this first element 300. Especially... Figure 3 As can be seen in b), the adhesion layer 301 has two layers: an intermetallic layer 302 and an impregnation layer 303. In the present case, the intermetallic layer 302 comprises an Al-Fe alloy, and the impregnation layer 303 comprises an Al-Si alloy with a Si content ranging from a minimum of about 5% by weight to a maximum of about 20% by weight. Furthermore, Figure 3 a) The thickness of the impregnated layer is specified as 307, and Figure 3 b) indicates the thickness of the intermetallic layer is 306. For Figure 3 The brake drum section shown has an impregnation layer 307 with a thickness ranging from a minimum of about 62 μm to a maximum of about 76 μm, and an intermetallic layer 306 with a thickness ranging from a minimum of about 10 μm to a maximum of about 19 μm. Figure 3 a) It can be seen that a segment of the second element 304 exists above the impregnation layer 303. The second element 304 has a second metallic material, which is made of an aluminum alloy and contains at least 75% by weight Al. Furthermore, in Figure 3 a) also schematically marks the roughness profile R of the first element. t The overall height is 305.

[0071] Figure 4 The diagram illustrates the section 400 of the measuring structure used to determine the average shear strength. Here, a sample ring 401 is placed on a support 402 and held in place by a clamping device 403. A press head 404 is located on the side facing the clamping device 403, which presses the sample ring 401. The press head is designed to apply pressure to the inner ring (first element 405). The sample ring 401 is a ring cut from the brake drum to be tested, and the width t of the sample ring 401 is approximately 5 mm. Figure 4 The diagram shows a first element 405, a second element 407, and an optional adhesive layer 406 located between the first and second elements, wherein the first element is advantageously a blank casting ring. The sample ring 401 has an inner diameter, wherein this inner diameter is the inner diameter 408 of the first element, and the inner diameter is, for example, approximately 90 mm. Furthermore, Figure 4 The figure also illustrates the first element, for example, with an outer diameter of 100 mm 409, followed by either an optional adhesive layer 406 or a second element 407. The second element 407, in turn, has an outer diameter of, for example, 120 mm 410. During the test (not shown here), the first element 405 is pressed with an indenter until the specimen breaks or the load limit of the press is reached.

[0072] Figure 5a , Figure 5b and Figure 5c The diagram illustrates the method used to determine the area A of the lateral concave portion. UC The method is as follows. As previously described, a cross-sectional grinding disc 500 is prepared from the sample to be tested, such as... Figure 5a As illustrated in the diagram. Furthermore, Figure 5a The measurement section L, selected as 25 mm, is also shown, along with the inner diameter ID, reference diameter GD, and outer diameter OD of the test specimen ring. Figure 5b The contour filtering is illustrated in the figure. As mentioned earlier, a reference area A0 is first determined based on the inner diameter ID and the initial outer diameter value OD0 (which initially still contains all contour peaks). Then, the outer diameter OD is moved towards the inner diameter ID until the summed cross-sectional area of ​​the detected specimen reaches 90% of the reference area A0. Figure 5c This is used to illustrate how the areas (A1, A2, ..., A) constituting the concave portion are analyzed. n The area A of the concave side is determined by summing the results. UC The method.

[0073] The invention will be described in detail below with the aid of examples, but the scope of the invention is not limited thereto: Example IE1 according to the present invention a) A brake drum is manufactured according to Example IE1 of the invention, wherein a first element having a hollow cylindrical shape is made of gray cast iron by centrifugal casting, and the roughness profile R of the first element facing the second element is... t The overall height is at least approximately 500 μm and at most approximately 1200 μm. On the outer side, i.e., the side facing the second element, an adhesion layer with a thickness of at least approximately 70 μm and at most approximately 100 μm is first applied. The application of the adhesion layer is achieved by immersion in a immersion bath containing a melt of an Al-Si alloy having a Si content of at least approximately 5% to at most approximately 20% by weight. The resulting adhesion layer has an intermetallic layer and an immersion layer, wherein the intermetallic layer is formed on the surface of the first element oriented towards the second element, and the immersion layer is formed on the intermetallic layer. The intermetallic layer contains an Al-Fe alloy, and the immersion layer contains an Al-Si alloy with a Si content of at least approximately 5% to at most approximately 20% by weight. The thickness of the resulting intermetallic layer is at least approximately 10 μm and at most approximately 20 μm. The thickness of the immersion layer is at least approximately 60 μm and at most approximately 80 μm. On the side of the impregnation layer opposite to the intermetallic layer, a second element is obtained by gravity casting with an aluminum alloy of type MAHLE M174 (with a Si content of at least about 11% to at most about 13% by weight). For the specific composition of the aluminum alloy of type MAHLE M174, please refer to, for example, US 7533649 B2.

[0074] This resulted in the brake drum. The outer diameter of the first element (the engagement diameter of the brake drum) is approximately 98.1 mm.

[0075] b) To further test the characteristics of the brake drum, a sample ring with a width t of approximately 5 mm was cut from the brake drum. Based on the engagement diameter D of approximately 98.1 mm of the brake drum or the cut sample ring, the total area to be tested was determined to be 1541 mm². 2 This total area will be used as the basis for subsequent calculations.

[0076] A test without prior temperature loading was performed (Ring 1). Three other tests were performed after heat loading. To ensure good reproducibility, three sample rings of the same brake drum were tested at each measurement point, and the results were averaged. For the post-heat loading tests, the sample rings were heated to approximately 400°C (Ring 2), approximately 450°C (Ring 3), and approximately 500°C (Ring 4), and held at each temperature for approximately 4 hours. The idea behind this temperature loading is to simulate the temperature rise of the brake drum during operation, especially during repeated heavy braking.

[0077] To test the combination of the first and second components, the sample rings were placed into a Zwick 200kN press, and the indenter was pressed down onto the sample rings from above (see also...). Figure 4 (The measurement structure is described in the text). Here, the indenter presses down on the inner ring of the sample ring (composed of a first element containing metallic material). The indenter moves forward at a speed of 10 mm / min. Although fractures are observed in each sample, the fractures do not occur at the adhesion layer, but rather within the second metallic material. Table 1 below lists the area A, temperature of the thermal load, and average applied force F for all samples. 平均 Mean shear strength σ 剪切,平均 And the results.

[0078] Here, the average shear strength σ 剪切,平均 The formula is calculated by dividing the average applied force by the area, as follows: σ 剪切,平均 = F / A Table 1

[0079] Therefore, these results regarding the shear strength of the sample rings, namely ring-1, ring-2, ring-3, and ring-4, demonstrate that, due to the proposed adhesive layer, particularly good adhesion is achieved between the first element containing metallic material and the second element containing metallic material.

[0080] c) Furthermore, the contact thermal resistance between the first element containing metallic material and the second element containing metallic material is determined. This contact thermal resistance plays a crucial role in the dissipation of heat generated during braking. For this purpose, sample rings are first cut as described in point b), and then cross-sections are separated from these sample rings. The contact thermal resistance can be calculated based on the sample thickness (d) and the thermal conductivity (λ) of the material using the following formula:

[0081] The thermal conductivity required to calculate the contact thermal resistivity was determined using a laser flash method with a NETZSCH LFA 467Hyperflash® instrument. Here, the front side of a planar parallel specimen is heated with short energy pulses. An infrared detector detects the associated temperature rise on the back side of the specimen. The thermal conductivity can be calculated from this temperature rise. and specific heat capacity Then, using density Thermal conductivity can be calculated using the following formula:

[0082] The measured contact thermal resistivity is approximately 2.6. 10-6 m 2 K / W. The measurement error is determined to be approximately ±5.2. 10 -7 m 2 K / W.

[0083] Comparison Example CE1

[0084] a) For comparison, a brake drum was manufactured according to comparative example CE1, wherein a first element having a hollow cylindrical shape was made of gray cast iron by centrifugal casting, and the roughness profile R of the first element facing the second element was... t The overall height is at least 500 μm and at most 1200 μm. Compared with Example IE1 according to the invention, instead of applying an adhesive layer, the second element is obtained directly on the first element by casting with an aluminum alloy (EN AB-46000 according to DIN EN 1676 and DIN EN 1706, also known as AlSi9Cu3) by die casting.

[0085] This yielded the brake drum. The outer diameter of the first element (the engagement diameter of the brake drum) is approximately 87.7 mm.

[0086] b) To further test the characteristics of the brake drum, a sample ring with a width t of approximately 5 mm was cut from the brake drum. Based on the approximately 87.7 mm engagement diameter D of the brake drum or the cut ring, the total area to be tested was calculated to be 1378 mm². 2 .

[0087] Subsequently, the procedure was performed using a method similar to that of Example IE1 according to the invention. Tests were performed after a temperature load (cycles 5, 6, and 7). To ensure good reproducibility, three sample cycles from the same brake drum were tested again for each measurement point, and the results were averaged.

[0088] The results are summarized in Table 2. For all specimen rings, fracture was observed at the boundary between the first and second elements, and the measured average shear strength σ 剪切 The sample ring is lower than that of Example IE1 according to the present invention.

[0089] Table 2

[0090] c) Similar to Example IE1 according to the present invention, the contact thermal resistivity was also determined for Comparative Example CE1. The contact thermal resistivity obtained here is approximately 1.1. 10 -5 m 2 K / W. The measurement error is determined to be approximately ±1.5. 10 -6 m 2 K / W.

[0091] This means that, for example IE1 according to the present invention, the heat generated during braking can be dissipated faster than that of comparative example CE1.

[0092] List of reference numerals

[0093] 100: Brake drum

[0094] 101: The first element of the brake drum

[0095] 102: The second element of the brake drum

[0096] 200: Providing a first component comprising a first metallic material

[0097] 201: Heating the first element containing the first metallic material.

[0098] 202: Immerse the first component in the impregnation tank.

[0099] 203: Allow the first element to remain in the impregnation tank.

[0100] 204: Remove the first component from the impregnation tank.

[0101] 205: Place the first component into the mold and close the mold.

[0102] 206: The first element is cast and encased with a second metallic material to form the second element.

[0103] 300: Segment of the first element

[0104] 301: Adhesive layer, comprising an intermetallic layer and an impregnation layer.

[0105] 302: Intermetallic layer

[0106] 303: Impregnated layer

[0107] 304: Truncation of the second element

[0108] 305: Roughness profile R of the first element t Overall height

[0109] 306: Thickness of the intermetallic layer

[0110] 307: Thickness of the impregnated layer

[0111] 400: The section of the measuring structure used to determine shear strength.

[0112] 401: Specimen (Specimen Ring)

[0113] 402: Support for specimens (sample rings)

[0114] 403: A clamping device for specimens (sample rings).

[0115] 404: Pressure head

[0116] 405: First Component

[0117] 406: Optional adhesive layer

[0118] 407: Second Component

[0119] 408: Inner diameter of the first element

[0120] 409: Outer diameter of the first element

[0121] 410: Outer diameter of the second element

[0122] 411: Width t of the specimen (sample ring)

[0123] 500: Used to determine the area A of the concave portion. UC The cross-section of the test specimen.

[0124] L: Regarding the inner diameter ID used to determine the area A of the side recess. UC Length of the measurement section

[0125] ID: Used to determine the area A of the concave portion UC The inner diameter of the sample

[0126] GD: Used to determine the area A of the lateral concave portion. UC The reference diameter of the sample

[0127] OD: Used to determine the area A of the concave portion. UC outer diameter of the sample

[0128] OD0: Used to determine the area A of the lateral concave region before contour filtering. UC outer diameter of the sample

[0129] A0: Based on the inner diameter ID and the area A before contour filtering, used to determine the side concave region. UC The reference area of ​​the outer diameter of the sample

[0130] A1, A2, ..., A n The areas that make up the concave portion

Claims

1. A brake drum (100) for a drum brake, the brake drum having a first element (101) comprising a first metallic material and a second element (102) comprising a second metallic material. - in, The first element (101) and the second element (102) are connected by casting technology. - Wherein, the first element (101) has a rough surface oriented toward the second element (102), - The brake drum also has an adhesive layer (301). - Wherein, the adhesive layer (301) is located between the first element (101) and the second element (102), - Wherein, the first element (101) and the second element (102) are connected by intermetallic bonding through the adhesive layer (301) in a material-locking manner.

2. The brake drum (100) according to claim 1, characterized in that, The melting temperature of the first metal material is higher than that of the second metal material.

3. The brake drum (100) according to any one of the preceding claims, characterized in that, The first metallic material contains Fe, and / or The second metallic material contains at least one element selected from the group consisting of Al and Mg. Preferably, the first metallic material contains at least 90% by weight Fe, and / or The second metallic material contains at least 75% by weight of at least one element selected from the group consisting of Al and Mg.

4. The brake drum (100) according to any one of the preceding claims, characterized in that, The first metallic material is made of gray cast iron.

5. The brake drum (100) according to any one of the preceding claims, characterized in that, The overall height R of the roughness profile of the surface of the first element (101) facing the second element (102) according to DIN EN ISO 4287:2010. t The minimum is approximately 500 μm and the maximum is approximately 1200 μm.

6. The brake drum (100) according to any one of the preceding claims, characterized in that, The rough surface of the first element oriented toward the second element has a side recess, wherein the rough surface of the first element oriented toward the second element preferably has at least about 0.36 mm in a 25 mm segment L. 10 5 μm 2 And the maximum is approximately 30 10 5 μm 2 The area A of the concave side UC .

7. The brake drum (100) according to any one of the preceding claims, characterized in that, The thickness of the adhesion layer ranges from a minimum of approximately 10 μm to a maximum of approximately 500 μm. Preferably, the thickness of the adhesive layer is from a minimum of about 40 μm to a maximum of about 200 μm.

8. The brake drum (100) according to any one of the preceding claims, characterized in that, The adhesion layer (301) comprises at least one intermetallic layer (302) and at least one impregnation layer (303). The at least one intermetallic layer (302) is located on the surface of the first element oriented toward the second element, and the at least one impregnated layer (303) is located on the at least one intermetallic layer and oriented toward the second element.

9. The brake drum (100) according to any one of the preceding claims, characterized in that, i) The at least one intermetallic layer (302) comprises at least one alloy selected from the group consisting of Al5Fe2, Al-Fe alloys and Al-Fe-Si alloys, and / or ii) The at least one impregnation layer (303) comprises an Al-Si alloy having a Si content of at least about 5% by weight and at most about 20% by weight.

10. The brake drum (100) according to any one of the preceding claims, characterized in that, The second element (102) containing the second metallic material is a die-cast element.

11. The brake drum (100) according to any one of the preceding claims, characterized in that, The second element (102) containing the second metallic material is a metal mold casting element.

12. The brake drum (100) according to any one of the preceding claims, characterized in that, Mean shear strength σ 剪切,平均 It should be at least 130 MPa.

13. The brake drum (100) according to any one of the preceding claims, characterized in that, The average shear strength σ of the brake drum after 4 hours of heat load at 450°C was measured. 剪切,平均 It should be at least 110 MPa.

14. A method for manufacturing a brake drum (100) according to any one of the preceding claims, the method comprising steps a) to g): a) Provides a first element (101) comprising a first metallic material, wherein, The first element (101) has at least a partially rough surface. b) Heating the first element (101) containing the first metallic material. c) Immersing the first element (101) in an impregnation bath, the impregnation bath preferably having an impregnation bath temperature of at least about 600°C and at most about 900°C. d) The first element (101) is kept in the impregnation tank for a duration of at least about 1 minute and at most about 10 minutes. e) Remove the first element (101) from the impregnation tank. f) Place the first element (101) into the mold and close the mold. g) The first element (101) is cast and covered with a second metal material to form a second element (102), wherein the first element has a rough surface facing the second element.

15. The application of the brake drum (100) according to any one of claims 1 to 13 in a drum brake, preferably in a drum brake for a motor vehicle or a motorized two-wheeled vehicle.

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