Brake band for a disk of a disk brake

Abstract

The subject of the present invention is a disc brake band (2) for a disc brake (1), comprising an annular band body (6) arranged around the brake disc rotation axis or axis (XX). The band body (6) is made of gray cast iron, steel, aluminum, or an alloy thereof. The brake band (2) comprises at least one braking surface (2a or 2b), at least a portion of which includes an activating band body portion (7) for increasing the adhesive capacity of at least one protective surface coating (3) arranged on the surface of the activating band body portion (7), the protective surface coating (3) being made of at least one material with enhanced abrasion resistance. The activated band body portion (7) is arranged on the surface of the band body (6) and forms the outermost layer of the brake band (2) with the at least one protective surface coating (3). The activated band body portion (7) includes a rough profile (8) having at least one groove or channel (9) defined by at least one pair of protrusions (10 and / or 11 and / or 12), the at least one channel (9) extending along a path at least partially surrounding the rotation axis (XX). In a cross section along its longitudinal extension, the at least one channel (9) has a channel bottom (13) and two opposing channel sides (14, 15). The first channel side (14) forms an acute angle (a1) with the channel bottom (13), i.e., an angle (a1) less than 90 degrees. The second channel side (15) forms an obtuse angle (a2) with the channel side (13), i.e., an angle (a2) greater than 90 degrees.

Description

Technical Field

[0001] The present invention relates to a brake band and a disk for a disk brake, and a vehicle having the ventilated disk, which are not particularly limited to applications in the automotive field.

Background Art

[0002] In a disk brake, a brake caliper is generally arranged across the outer peripheral edge of a brake disk configured to rotate about a rotation axis (A - A) defining an axial direction (X - X). In the brake disk, a radial direction (R - R) substantially orthogonal to the axial direction (X - X), a circumferential direction (C - C) orthogonal to the axial direction (X - X) and the radial direction (R - R), and a local tangential direction (T - T), that is, more precisely, at the intersection of the axial direction and the radial direction, a tangential direction orthogonal to both the axial direction (X - X) and the radial direction (R - R) are defined.

[0003] As is well known, a disk for a disk brake consists of a bell configured to associate the disk with a hub of a vehicle, from which an annular portion named a brake band, intended to cooperate with the brake pads of the caliper, extends. In the case of a ventilated type disk, the brake band is made of two opposed plates, which are connected to each other by connecting elements in the form of, for example, pins or fins. The outer surfaces of the two plates define opposing brake surfaces, and the inner surfaces, together with the pins or fins, define air passages for cooling the disk, and these air passages are traversed by a centrifugal air flow during the rotational movement of the disk itself.

[0004] The brake band is intended to cooperate with a disk brake caliper configured to apply a braking action to a vehicle by applying friction to the opposite surfaces of two plates named brake surfaces by the pads.

[0005] The controlled interaction between the opposing brake surfaces of the opposing brake pads and the brake band determines the braking action by friction, thereby enabling deceleration or stopping of the vehicle.

[0006] Generally, brake discs are made of gray cast iron or steel. In fact, this material can obtain relatively low cost and good braking performance (especially in terms of wear resistance). Discs made of carbon or carbon ceramic materials offer much better performance, but the cost is much higher.

[0007] The limitations of conventional discs made of cast iron or steel are related to excessive wear. Regarding discs made of gray cast iron, another very negative aspect is related to excessive surface oxidation and the associated formation of rust. This rust not only affects the performance of the brake disc, but also affects the appearance because the rust on the brake disc is aesthetically unacceptable to the user. In response to such problems, attempts have been made to apply a protective film to gray cast iron and steel discs. The protective coating, on the one hand, reduces the wear of the disc, and on the other hand, protects the gray cast iron base from surface oxidation, thereby preventing the formation of a rust layer.

[0008] The protective coatings currently available and applied to gray cast iron or steel discs provide wear resistance, but are subject to peeling that determines peeling from the disc itself.

[0009] This type of protective coating is described, for example, in the patent US4715486 regarding low-wear disk brakes. In particular, the disk made of cast iron has a coating made of particulate material deposited on the disk by high kinetic energy impact technology. According to the first embodiment, the coating contains 20% to 30% tungsten carbide, 5% nickel, and the remaining part is a mixture of chromium carbide and tungsten. According to the second embodiment, the coating contains 80% to 90% tungsten carbide, up to 10% cobalt, up to 5% chromium, and up to 5% carbon.

[0010] When applying the coating by thermal spraying technology, one of the reasons for the peeling of the conventional protective coating from a disk made of gray cast iron or steel is the presence of free carbon in the protective coating. In fact, this carbon has the property of combining with oxygen contained in the protective film and burning. As a result, microbubbles are formed inside the coating, preventing sufficient adhesion of the coating to the disk, and thereby the coating may be easily removed.

[0011] From the above, it is clear that a disk made of gray cast iron or steel with a protective coating cannot currently be used in the field of brake systems.

[0012] However, considering the advantages in terms of wear resistance guaranteed by the protective coating, there is a strong need in the art to solve the above-mentioned drawbacks with reference to the prior art. In particular, there is a need to have a gray cast iron or steel disk with enhanced wear resistance and a strong protective coating over time.

[0013] A solution to the above-mentioned problem has been proposed by the applicant of this application in the international application WO2014 / 097187 regarding a disk made of gray cast iron or steel.

[0014] In the case of a disc made of gray cast iron or steel, it is to create a protective coating on the braking surface of a disc brake obtained by depositing a particulate material consisting of 70 to 95% by weight of tungsten carbide, 5 to 15% by weight of cobalt and 1 to 10% by weight of chromium. The deposition of the particulate material is obtained by HVOF (High-Velocity Oxygen Fuel) or HVAF (High-Velocity Air Fuel) or KM (Kinetic Metallization) technology.

[0015] More specifically, according to the solution provided in WO2014 / 097187, it is possible to obtain a protective coating with a high bonding strength that guarantees a high degree of fixation on gray cast iron or steel by a combination of HVOF, HVAF, or KM film-forming technology and the chemical composition used for the formation of the coating. The particulate material used does not contain even a trace amount of free carbon (C). For this reason, the peeling phenomenon of the protective coating can be significantly reduced.

[0016] By adopting the solution provided in WO2014 / 097187 for a disc made of gray cast iron or steel, or in WO2014 / 097186 for a disc made of aluminum or an aluminum alloy, it is possible to significantly reduce the peeling phenomenon of the protective film found in the known prior art, but it cannot be completely eliminated. In fact, even in a disc made of aluminum or an aluminum alloy or gray cast iron or steel provided with a protective coating manufactured according to WO2014 / 097186 or WO2014 / 097187, the peeling and sinking of the protective coating occur less frequently than in the known prior art, but continue to occur.

[0017] Partial solutions to the problems of peeling and sinking of the protective coating have been provided by the applicant in the international application WO2017046681A1. In particular, such solutions include creating a base protective coating between the protective coating and the brake surface, consisting of 65% to 95% chromium carbide (Cr3C2) and the remaining nickel-chromium (NiCr). Surface protection coating is made on the base protective film and consists of 80 to 90% by weight of tungsten carbide (WC) and the remaining cobalt (Co). The deposition of the particulate material for both protective films is carried out by HVOF (High-Velocity Oxygen Fuel) or HVAF (High-Velocity Air Fuel) or KM (Kinetic Metallization) technology. Such solutions are particularly applicable to disks made of gray cast iron or steel.

[0018] Compared with the prior art, the technical solution provided by WO2017046681A1 provides a great improvement in terms of reducing the failure and peeling of the protective coating. However, the results obtained are not entirely satisfactory.

[0019] Therefore, in order to ensure wear resistance over time, there continues to be a need in the relevant field for disks made of gray cast iron, steel, aluminum or aluminum alloy, with a protective coating that is less or much less affected by peeling than known solutions.

[0020] The document DE102008022225 is one of the first examples of the "activation" of a surface intended to receive a protective layer. Activation means the machining of a surface that can create a shape adapted for a geometric bond with the protective layer.

[0021] This solution discloses a method of creating a cavity in a body by machining, where the base of the cavity is connected to the body surface by a side surface obtained by removing a part of the body material adjacent to the cavity by emitting a laser inclined at an angle of 5 to 60° and 115 to 175° with respect to a tangent plane lying on the body surface, and a semi-open cavity having a side surface forming an undercut is formed. The cavity is covered by applying a coating or a protective layer.

[0022] The cavity is formed as a groove and extends in a preferred direction so as to cover the entire region of interest. The surface to be treated is the inner peripheral surface of a cylinder (cylinder liner) of a reciprocating piston engine having a cylindrical shape and being rotationally symmetric with respect to the longitudinal axis. The cavity runs along the inner circumference of the cylinder bore or the cylinder liner and extends helically or perpendicularly with respect to the longitudinal axis of the cylinder liner. The undercut forms an opening angle of 0 to 45° and / or 180 to 135° with respect to the longitudinal axis of the cylinder liner.

[0023] This solution is very complicated to implement due to the shape of the cavity itself.

[0024] Similar solutions applied to brake discs are known from US2255024, US2016178019 and US2005221057A1.

[0025] Document DE102010052735 shows a brake disc including a brake band having an annular friction surface coated with a thermal spray coating, where a plurality of grooves or cavities extend over the annular friction surface, forming undercuts on both vertical or side walls of each groove and providing an engagement bond for the thermal spray coating. The grooves or slots extend helically along the surface and cover the entire range of the friction surface.

[0026] This solution further improves the grip between the protective coating and the body of the brake band by further reducing peeling.

[0027] However, the presence of the undercut obliges the use of complex turning operations with multiple cutting tools that must necessarily enter the surface immediately over the entire height of the slot, thus obliging machining in a single tool path, which necessarily starts from the outer edge of the brake band and, in fact, due to the presence of the bell or the connection means to the bell, usually has difficult access to the inner edge.

[0028] For the same reason, i.e., due to the presence of an undercut on the side of the groove or slot, the tool is forced to follow a helical path and, if it cannot exit from the inner edge of the brake band, is forced to follow the entire cutting path and travel in the reverse path to exit from the outer edge of the brake band. This imposes the use of a tool with multiple cutting edges configured to act in both one direction of the helical cutting path and the opposite direction to withdraw the tool, without which, if the tool finds even slight imperfections, excessive roughness in the walls of the channel or groove, the material of the brake band may tear or split, and the brake band may not be acceptable in production, increasing costs and labor and potentially interrupting normal production.

[0029] Therefore, there remains a strong need for a shape of the groove or slot that solves the aforementioned drawbacks. SUMMARY OF THE INVENTION

[0030] An object of the present invention is to provide a brake band in which the protective coating does not peel off or peels off to a lesser extent than currently known solutions in order to ensure wear resistance over time.

[0031] This object and other objects and advantages are achieved by the brake band according to claim 1, the disk brake disk according to claim 15, the vehicle according to claim 16, the method for manufacturing the band according to claim 17, and the tool for the manufacturing method according to claim 19.

[0032] Some advantageous embodiments are the subject of the dependent claims.

[0033] From the analysis of this solution, it has emerged how the proposed solution can enable an improved grip or engagement between the protective coating and the body of the brake band and how flaking can be reduced.

[0034] Furthermore, the proposed solution is not necessarily spiral but also annular, closed in itself, and is suitable for machining a rough profile defined by a plurality of protrusions and grooves or slots that can be made by machining by chip removal or by laser engraving or by plastic deformation, in particular in a path that is not closed in itself but does not end at the edge of the brake band.

[0035] In particular, the proposed solution is also suitable for multi-pass machining and, in the case of tools with multiple cutting edges, does not oblige to follow the cutting path or to finish the machining performed, avoids deterioration of the machining finish or breakage of the cutting edges of the tool, avoids or limits the waste of part of the production and the interruption of normal production, and avoids the deterioration of costs and effort.

[0036] Further features and advantages of the present device, brake disc, and vehicle will become apparent from the following description of its preferred embodiments by way of non-limiting example, with reference to the accompanying drawings.

Brief Description of the Drawings

[0037]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

DETAILED DESCRIPTION OF THE INVENTION

[0038] Elements or components common to the described embodiments are hereinafter denoted using the same reference numerals.

[0039] Referring to the foregoing figures, reference numeral 1 denotes a brake disk as a whole according to the present invention.

[0040] According to a general embodiment of the present invention shown in the accompanying drawings, the disk brake 1 comprises a brake band 2 having two opposing brake surfaces 2a and 2b, each of which at least partially forms one of the two main surfaces of the disk.

[0041] The brake band 2 is made of a base material selected from gray cast iron or steel. Preferably, the brake band is made of gray cast iron. In particular, the entire disk is made of gray cast iron. Therefore, in the following description, a disk made of gray cast iron is mentioned, but it does not exclude the possibility that it is made of steel.

[0042] Brake The disk 1 comprises the following.

[0043] - A base protection coating 30 covering at least one of the two brake surfaces of the brake band; and

[0044] - A surface protection coating 3 covering at least one of the two brake surfaces 2a, 2b of the brake band and covering the base protection coating 30.

[0045] The base protection coating 30 is composed of chromium carbide (Cr3C2) and nickel chromium (NiCr), or nickel chromium (NiCr), iron (Fe), molybdenum (Mo), cobalt (Co), manganese (Mn) and aluminum (Al), and is obtained by a thermal spraying film-forming technique on the disk 1, preferably the HVOF (High-Velocity Oxygen Fuel) technique of particulate coating components, or the HVAF (High-Velocity Air Fuel) technique or the KM (Kinetic Metallization) technique.

[0046] The surface protection coating 3 is composed of tungsten carbide (WC), iron (Fe), chromium (Cr), aluminum (Al), and is preferably obtained by depositing particulate tungsten carbide (WC), iron (Fe), chromium (Cr), aluminum (Al) on the base protection coating 30 by the HVOF (High-Velocity Oxygen Fuel) method, or by forgiving techniques such as the HVAF (High-Velocity Air Fuel) method or the KM (Kinetic Metallization) method.

[0047] According to the present invention, as schematically shown in FIGS. 2 and 3, the brake surface coated by the base protection coating 3 is formed by a soft nitriding layer 300 of a base metal (gray cast iron or steel), and has a rough profile in a radial or circumferential cross section with respect to the center of the brake band.

[0048] Therefore, Base protection coating 30 is not directly fixed on the base material forming the brake band, but is fixed on the above-mentioned soft nitriding base material layer 300.

[0049] In particular, the above-mentioned rough profile extends perpendicular to the surface at a height between 30 and 200 μm, and is defined by a plurality of protrusions 20 spaced from each other at a pitch between 300 and 2000 μm - radially or circumferentially with respect to the center of the brake band. Preferably, the above-mentioned protrusions are distributed in a regular pattern on the brake surface of the disk 1. However, an irregular distribution pattern may be provided.

[0050] Advantageously, as schematically shown in FIG. 6, the above-mentioned protrusion 20 has a profile to be described in more detail below.

[0051] According to an alternative embodiment, the above-mentioned rough profile may have a roughness Ra between 0.8 and 2 when obtained by turning, and a roughness Rz between 10 and 80 when obtained by sandblasting.

[0052] Preferably, the soft nitriding layer 300 is obtained by subjecting the base material to ferritic soft nitriding treatment.

[0053] According to a preferred embodiment, the soft nitriding layer 300 has a depth of 2 to 30 μm and a hardness value greater than 300 HV in microhardness.

[0054] According to a particularly preferred embodiment, the soft nitriding layer 300 includes an oxide top layer 330 made of magnetite Fe3O4 acting as an interface with the above-mentioned Base protection coating 30.

[0055] Preferably, the top oxide layer 330 made of magnetite Fe3O4 has a thickness between 2 and 10 μm.

[0056] Preferably, Base protection coating 30 is composed of the following.

[0057] - 65% to 95% is chromium carbide (Cr3C2), and the remainder is nickel chromium (NiCr); or

[0058] - Nickel-chromium (NiCr) with a nickel content of 40 wt% to 75 wt%, a chromium content of 14 wt% to 30 wt%, and the balance being iron (Fe), molybdenum (Mo), cobalt (Co), manganese (Mn), and aluminum (Al).

[0059] In particular, the base protection coating 30 may have the following composition.

[0060] - 93 wt% of chromium carbide (Cr3C2) and 7 wt% of nickel chromium (NiCr).

[0061] - 90 wt% of chromium carbide (Cr3C2) and 10 wt% of nickel chromium (NiCr).

[0062] - 75 wt% of chromium carbide (Cr3C2) and 25% of nickel-chromium (NiCr); or

[0063] - 65 wt% of chromium carbide (Cr3C2) and 35 wt% of nickel-chromium (NiCr).

[0064] Preferably, the base protection coating 30 is composed of 75 wt% of chromium carbide (Cr3C2) and 25 wt% of nickel-chromium (NiCr). In particular, the nickel-chromium (NiCr) consists of 80% or more nickel and 20% or more chromium.

[0065] Preferably, Surface protection coating3 consists of 75% to 87% by weight of tungsten carbide (WC), with the balance being iron (Fe), chromium (Cr), and aluminum (Al). More preferably, Surface protection coating 3 is composed of 85% by weight of tungsten carbide (WC) and 15% by weight of iron (Fe), chromium (Cr), and aluminum (Al).

[0066] Advantageously, the thickness of the base protection coating 30 is configured to be between 20 μm and 80 μm, preferably equal to 50 μm, while the thickness of the surface protection coating 3 is configured to be between 30 μm and 90 μm, preferably equal to 60 μm. The thicknesses of the two protection coatings 3 and 30 are calculated with respect to the portion above the rough state. Thus, these are the minimum thickness values that do not take into account the thickness of the coating that can be used to fill the roughness dips / pits.

[0067] Overall, as schematically shown in FIG. 6, the two protection coatings 3 and 30 completely fill the roughness of the brake surface and preferably spread over the rough profile in a layer of thickness within the intervals defined above.

[0068] The presence of the aforementioned soft nitrided layer 300 at the interface between the untreated base material and Base protection coating 30 has unexpectedly been found to significantly reduce the occurrence of coating peeling phenomena compared to a brake disc having a similar protective coating but no soft nitrided layer, although it is not completely eliminated.

[0069] All possible technical explanations are non - limiting in all cases, but unlike conventional protective coatings, the soft nitrided layer, however, is not composed of a layer of material applied to the base material itself and is based on the fact that it protects the base material from corrosion. In other words, there is no net separation region between the untreated base material and the soft nitrided layer 300. The soft nitrided layer is precisely the layer in which the base material has been morphologically and chemically modified by the soft nitriding treatment. Thus, the transition from the untreated base material to the soft nitrided metal may be progressive.

[0070] From this perspective, the roughness profile of the braking surface on which the soft nitrided layer 300 is formed further emphasizes the irregularity of the transition from the soft nitrided base material to the untreated base material, thereby boosting the positive effect.

[0071] The roughness profile of the braking surface on which the soft nitrided layer 300 is made further promotes the mechanical adhesion between the base protection layer 30 and the soft nitrided layer.

[0072] Also, Soft nitrided layer It has been experimentally confirmed that the presence of 300 does not affect the performance of the protective surface coating 3 in terms of both wear resistance and tribological behavior (friction, fading, conformity) under normal environmental conditions.

[0073] Finally, it has been experimentally confirmed that the presence of the soft nitrided layer 300 improves the resistance in the presence of environmental stresses (thermal shock and salt damage).

[0074] The anti-corrosion effect provided by the soft nitrided layer is emphasized in the preferred case where the soft nitrided layer 300 consists of a magnetite Fe 3 O and an oxide top layer 330 consisting of 4.

[0075] In any case, such rust prevention effect is further enhanced by the presence of the base coating layer 30. Such Base protection coating Depending on the composition of 30 (Cr3C2 and NiCr, or NiCr and Fe and Mo and Co and Mn and Al) and the film formation method, such base coating 30 also has an anti-corrosion effect on the braking surface of the disc.

[0076] The anti-corrosion effect is beneficial for the integrity of the surface protection coating 3 and its adhesion to the disc.

[0077] The base protection coating 30 also performs a mechanical "damper" function for the surface protection (wear-resistant) coating 3. In fact, formed by Cr3C2 and NiCr, or by NiCr, Fe, Mo, Co, Mn and AlBase protection coating 30 is formed by tungsten carbide, iron, chromium, and aluminum and Surface protection coating has a ductility higher than that of 3. Thereby, Base protection coating elastic behavior is imparted to 30, and the stress applied to the disk during use can be - at least partially - relieved. Therefore, the base protection coating 30 acts as a kind of damper or cushion between the disk and the surface protection coating 3. Thereby, direct transmission of stress between the two parts is prevented, thereby reducing the risk of inducing cracks in the surface protection coating 3.

[0078] Regarding the wear-resistant function, the surface protection coating 3 is not biased either by the presence of the base protection coating 30 or Soft nitrided layer by 300 (which may have an oxide top layer 330) either.

[0079] For the sake of simplicity, next, the brake disk 1 will be described together with the method according to the present invention.

[0080] The brake disk 1 is preferably manufactured using the method according to the present invention described below, but it is not necessarily so.

[0081] According to a general embodiment of the method according to the present invention, this method consists of the following operating steps.

[0082] Step (a) of preparing a brake disk including a brake band 2 having two opposing brake surfaces 2a, 2b, each of which defines at least a part of two main surfaces of the disk, and the brake band is made of gray cast iron or steel.

[0083] Step (b) of subjecting at least one of the brake surfaces (2a or 2b) to a processing treatment designed to increase its surface roughness.

[0084] Step (c) of nitrocarburizing the braking surface having the increased surface roughness and obtaining 300 on such a surface. Soft nitrided layer

[0085] Soft nitrided layer Step (d) of depositing a particulate material consisting of the following on 300 by the following technique.

[0086] - Chromium carbide (Cr3C2) and nickel-chromium (NiCr), or

[0087] - Nickel-chromium (NiCr), iron (Fe), molybdenum (Mo), cobalt (Co), manganese (Mn) and aluminum (Al).

[0088] . Using a thermal spraying technique, preferably HVOF (High-Velocity Oxygen Fuel) technique or HVAF (High-Velocity Air Fuel) technique or KM (Kinetic Metallization) technique, cover at least one of the two braking surfaces of the brake band with the soft nitrided layer 300 interposed therebetween Base protection coating to form 30.

[0089] Base protection coating 30 On top of, deposit a particulate material consisting of tungsten carbide (WC), iron (Fe), chromium (Cr), and aluminum (Al) by a spray deposition technique, preferably HVOF (High-Velocity Oxygen Fuel) technique, or HVAF (High-Velocity Air Fuel) method, or KM (Kinetic Metallization) method, which consists of tungsten carbide (WC) and iron (Fe), chromium (Cr), aluminum (Al) and covers at least one of the two braking surfaces of the brake band Surface protection coating to form 3 in step (e).

[0090] In particular, the treatment performed in step (b) may be performed to generate a rough profile on the surface defined by a plurality of protrusions 20 that extend orthogonally to the surface at a height h between 30 and 200 μm and are spaced from each other - radially or circumferentially with respect to the center of the brake band - at a pitch P between 300 and 2000 μm.

[0091] Advantageously, such projections 20 have a profile which will be described in more detail below. Due to the presence of this profile, the mechanical adhesion ability of 30 on the soft nitrided layer 300 is improved. Base protection coating The mechanical adhesion ability of 30 is improved.

[0092] In particular, the step (b) is carried out in a processing step by chip removal, or by laser cutting, or by plastic deformation.

[0093] Advantageously, the aforementioned step (b) may alternatively be carried out in a machining process by fine turning with a roughness Ra between 0.8 and 2.

[0094] According to a further alternative, the aforementioned step b) is carried out in a sandblasting working process with a roughness Rz between 10 and 80.

[0095] Preferably, the step (c) of soft nitriding is obtained by ferritic soft nitriding treatment.

[0096] Advantageously, the soft nitriding step c) Soft nitrided layer is carried out such that 300 has a depth between 2 and 30 μm and a hardness value greater than 300 HV in microhardness.

[0097] According to a preferred embodiment of the method according to the present invention, after the step (c) of nitrocarburizing and before the step (d) of deposition, Soft nitrided layer a step (f) of post-oxidation of 300 follows, to obtain an oxidation top layer 330 made of magnetite Fe3O4.

[0098] Preferably, the oxidation top layer 330 made of magnetite (Fe3O4) has a thickness configured between 2 and 10 μm.

[0099] Due to the presence of the oxidation top layer 330 made of magnetite (Fe3O4), the rust prevention effect of the soft nitrided layer on the untransformed base material is improved.

[0100] The soft nitriding treatment is a process well-known to those skilled in the art, and therefore, no detailed description will be given. Here, it is limited to providing some general information for clarification purposes.

[0101] The soft nitriding treatment is a thermochemical surface hardening treatment carried out in the ferrite phase at a relatively low temperature (550°C to 580°C) under conditions that enable the diffusion of nitrogen and carbon in the surface region of the workpiece. In particular, the means employed in the process of implementing the diffusion of nitrogen and carbon are salt bath; gas; plasma.

[0102] Soft nitriding treatment with a gas medium is preferred over soft nitriding treatment in a salt bath when high levels of uniformity and cleanliness are required (such as in blind cavities, grooves, threads, etc.).

[0103] The temperature employed in the soft nitriding treatment ensures the suppression of deformation.

[0104] As an alternative to ferrite soft nitriding treatment, ion nitriding treatment can be carried out. The latter has an atmosphere consisting of ammonia and methane at a temperature of 570°C, which is essentially different from the ferrite system.

[0105] In ion nitriding treatment, it is possible to arbitrarily change the type and depth of the surface components. And in the case of parts that must withstand fatigue and wear (such as brake discs), the formation of (Fe4N) layer or (Fe2 - 3CxNy) layer can be determined.

[0106] Preferably, the particulate material deposited in step (d) of the deposition for making the base protection coating 30 is composed of 65% to 95% chromium carbide (Cr3C2) and the remaining nickel - chromium (NiCr).

[0107] In particular, the particulate material deposited in step (b) of the deposition for making the base protection coating 30 can have the following composition.

[0108] - 93 wt% chromium carbide (Cr3C2) and 7 wt% nickel chromium (NiCr).

[0109] - 90 wt% chromium carbide (Cr3C2) and 10 wt% nickel chromium (NiCr).

[0110] - 75 wt% chromium carbide (Cr3C2) and 25 wt% nickel-chromium (NiCr); or

[0111] - 65 wt% chromium carbide (Cr3C2) and 35 wt% nickel chromium (NiCr).

[0112] According to a preferred embodiment, the particulate material deposited in step d) for manufacturing the base protection coating 30 consists of 75 wt% chromium carbide (Cr3C2) and 25 wt% nickel chromium (NiCr). In particular, the nickel-chromium (NiCr) consists of 80% nickel and 20% chromium.

[0113] Alternatively, the particulate material deposited in deposition step (d) for making the base protection coating 30 is based on nickel chromium (NiCr) with a nickel content by weight of 40% to 75% and a chromium content by weight of 14% to 30%, and the balance is iron (Fe), molybdenum (Mo), cobalt (Co), manganese (Mn) and aluminum (Al).

[0114] Preferably, Surface protection coating the particulate material deposited in step e) for depositing to make 3 consists of 75 wt% to 87 wt% tungsten carbide (WC) and the balance iron (Fe), chromium (Cr), aluminum (Al).

[0115] In particular, the particulate material deposited in step (e) for making the surface protection coating 3 consists of 10 wt% to 17 wt% iron (Fe), 2 wt% to 5.8 wt% chromium (Cr), 0.6 wt% to 2.2 wt% aluminum (Al), the balance being tungsten carbide (WC).

[0116] According to a preferred embodiment, the resulting Surface protection coating 3 consists of 85 wt% tungsten carbide (WC) and 15 wt% iron (Fe), chromium (Cr) and aluminum (Al).

[0117] Advantageously, the brake disc is centrally arranged with respect to the disc 1 and has an annular portion concentric with the brake band 2 or Fixing part 4 and comprises a portion configured to fix the disc to the vehicle. Fixing part 4 supports a connecting element 5 to the wheel hub (i.e., the bell). The bell may be integrally formed with the annular fixing portion (as shown in the attached figures) or may be separately formed and then fixed to the fixing portion by a suitable connecting element.

[0118] The annular fixing portion 4 can be made of the same material as the brake band, i.e., gray cast iron, or steel. Also, Connection element 5 can be made of aluminum or gray cast iron or other suitable materials. In particular, the entire disc (i.e., the brake band, the fixing portion, and the bell) can be made of gray cast iron.

[0119] Preferably, the brake band 2 is made by casting. Similarly, if they are made of gray cast iron, the fixing portion and / or the bell can be manufactured by casting.

[0120] The annular fixing portion can be made integrally with the brake band (as shown in the attached figures) or can be made as a separate body mechanically connected to the brake band.

[0121] Advantageously, the particulate material deposited in step d) for forming the base protection coating 30 has a particle size composed between 5 and 40 μm. By selecting values within such a range, it becomes possible to impart high properties such as deposition surface density and adhesion ability to the soft nitrided layer 300.

[0122] Preferably, Base protection coating the thickness of 30 is composed of a value equal to 20 μm to 80 μm, preferably 50 μm. By selecting values within such a range, it becomes possible to achieve an optimal balance between the effect of the antioxidant protection action and the limitation of the thermal expansion of the coating itself. That is, Base protection coating if the thickness of 30 is less than 20 μm, a sufficient antioxidant protection action cannot be obtained. On the other hand, if the thickness is greater than 80 μm, due to the thermal expansion occurring during the life cycle of the disc brake, adhesion may become incomplete over time.

[0123] Within the aforementioned thickness range, the base protection coating 30 can perform the aforementioned "damper" effect that helps maintain the integrity of the surface protection coating 3.

[0124] Advantageously, the particulate material in particulate form deposited in step (e) for forming the surface protection coating 3 has a particle size composed between 5 and 45 μm. By selecting values within such a range, it becomes possible to impart high properties such as density, hardness and limited porosity to the coating.

[0125] Preferably, the thickness of the surface protection coating 3 is configured to be between 30 μm and 90 μm, preferably equal to 60 μm. By selecting values within such a range, it becomes possible to achieve an optimal balance between the consumption of the protection layer and the limitation of the thermal expansion of the coating itself. That is, if the thickness of the protective film is less than 20 μm, when worn, it will be completely removed in an excessively short time. On the other hand, if the thickness is greater than 90 μm, due to the thermal expansion occurring during the life cycle of the disc brake, it may result in incomplete adhesion over time.

[0126] As described above, the thicknesses of the two protective films 3 and 30 are calculated in relation to portions above the rough state or more. Therefore, these are the minimum thickness values that do not consider the thickness of the coating that can be used to fill the roughness dips / pits.

[0127] Overall, as schematically shown in FIG. 6, the two protective coatings 3 and 30 completely fill the roughness of the brake surface and preferably develop on the rough profile with a layer of thickness within the interval defined above.

[0128] As already mentioned, the materials forming the base protective coating 30 [chromium carbide (Cr3C2) and nickel chromium (NiCr), or nickel chromium (NiCr), iron (Fe), molybdenum (Mo), cobalt (Co), manganese (Mn) and aluminum] and Surface protection coating the materials forming 3 (tungsten carbide, iron, chromium, aluminum) are preferably deposited in particulate form on the soft nitrided layer 300 and Base protection coating on 30 by the HVOF method or the HVAF method or the KM method, respectively.

[0129] These three deposition techniques are well known to those skilled in the art, and thus detailed description is omitted.

[0130] HVOF (High-Velocity Oxygen Fuel) is a powder spraying film forming technique using a spraying device equipped with a mixing combustion chamber and a spraying nozzle. Oxygen and fuel are supplied to the chamber. High-temperature combustion gas formed at a pressure close to 1 MPA passes through a convergent-divergent nozzle, transporting the powder material to an extremely supersonic speed (above MACH5). When the powder material is introduced into this high-temperature gas flow, the material rapidly melts and is accelerated to a speed on the order of 1000 m / s. When it collides with the deposition surface, the molten material is rapidly cooled, and a very dense and compact structure is formed by the impact of high kinetic energy.

[0131] The HVAF (High-Velocity Air Fuel) spraying technique is similar to the HVOF technique. The difference is that in the HVAF technique, air is supplied into the combustion chamber instead of oxygen. Therefore, the in-hand temperature becomes lower than that of the HVOF technique. As a result, the thermal degradation of the coating can be better controlled.

[0132] The KM (Kinetic Metallization) spraying method is a solid spraying process in which metal powder is sprayed from an ultrasonic spraying nozzle in two steps of accelerating and tribo-charging metal particles in an inert gas stream. Thermal energy is supplied to the carrier stream. The potential energy and thermal energy of the compressed inert gas stream are converted into the kinetic energy of the powder within the process. The particles accelerated and charged at high speed are directed towards the film-forming surface. When the metal particles collide with this surface at high speed, the particles are greatly deformed (about 80% in the direction perpendicular to the collision). Due to this deformation, the surface area of the particles becomes very large. As an effect of the impact, an intimate contact is formed between the particles and the deposition surface, thereby forming a metallic bond and a coating with a very dense and compact structure is formed.

[0133] Advantageously, as an alternative to the above three spraying methods that share the high kinetic energy impact spraying method, there are other techniques that utilize different spraying methods, but it is possible to produce a coating having a very dense and compact structure.

[0134] By combining the HVOF, HVAF, or KM spraying techniques with the chemical components used for the formation of the two protective coatings - base 30 and surface 3 -, it becomes possible to obtain a protective coating having a high bonding strength on the underlying material on which they are sprayed.

[0135] In particular, by the aforementioned combination, Soft nitrided layer 300 (in some cases Oxidation top layer having 330) on Base protection coating 30, and Base protection coating 3 on Surface protection coating 30, it is possible to obtain a high degree of anchoring for both.

[0136] The absence of free carbon (C), preferably not even in trace amounts in the final materials constituting the two protective coatings, helps to reduce the risk of delamination. In fact, in the case of coatings applied by thermal spraying techniques, it has been found that the cause of the delamination of conventional protective coatings from disks made of aluminum or aluminum alloys or gray cast iron or steel is the presence of free carbon in the protective coatings. This carbon has the property of combining with oxygen contained in the protective film and burning. As a result, microbubbles are formed inside the coating, preventing sufficient adhesion of the coating to the disk, and as a result, the removal of the coating becomes easier.

[0137] According to a particularly preferred embodiment of the present invention, the base protective coating 30 The material in particulate form deposited in step d) of the deposition for making and the surface protective coating 3 The material in particulate form deposited in step e) of the deposition for making are both deposited by the HVOF (High-Velocity Oxygen Fuel) technique. In fact, this technique has been found to be capable of achieving a composite protective coating (base + surface) that provides the best compromise in terms of wear resistance and friction performance - especially when related to the entire disk made of brake band or gray cast iron.

[0138] More specifically, according to experimental tests carried out in relation to the (preferred) HVOF (High-Velocity Oxygen Fuel) technique, it is possible to obtain a compact and uniform coating with a regular thickness close to the nominal value by the HVAF (High-Velocity Air Fuel) technique. Coatings made by HVOF are not compact and have a "spongy" appearance, with variable thickness.

[0139] The thermal shock tests conducted on samples with coatings made by HVOF and HVAF showed damage that only affected the WC + Fe, Cr, Al surface protection coatings found on all samples, which was found to consist of microcracks in the coatings. However, such microcracks seem to be more prominent in specimens with coatings made by the HVAF method. For this reason, the HVOF technique is more preferred.

[0140] In all cases, the base protection coating consisting of Cr3C2+Ni or NiCr+Fe+Mo+Co+Mn+Al is not affected after the thermal shock test, is always dense, adheres completely to the cast iron, and has no cracks.

[0141] As described above, the base protection coating 30 and the surface protection coating 3 cover at least one of the two braking surfaces of the brake band.

[0142] Hereinafter, the entire base protection coating 30 and surface protection coating 3 will be globally identified as the "composite protection coating" 3, 30.

[0143] Preferably, as shown in Figure 2, the disk 1 is provided with the "composite protection coating" 3, 30 that covers both braking surfaces 2a, 2b of the brake band 2.

[0144] In particular, the composite protection coating 3, 30 may cover only the brake band, on a single braking surface, or both.

[0145] According to the solution of the embodiment not shown in the attached drawings, the composite protection coating 3, 30 may also extend to other parts of the disk 1 as the annular fixing part 4 and the bell 5, covering the entire surface of the disk 1. In particular, the composite Coating 3, 30 may cover only the fixing part, in addition to the brake band, or Connection elementIt may only cover. That choice is substantially determined for reasons of appearance in order to achieve uniform coloring and / or finishing across the entire disc or part thereof.

[0146] Advantageously, the deposition of the particulate material for forming the composite protective coatings 3, 30 may be carried out in a differentiated manner on the surface of the disc, at least in terms of coating thickness.

[0147] In the brake band, the composite protective coatings 3, 30 can be made to have the same thickness on two opposing brake surfaces. As an alternative solution, the composite protective coatings 3, 30 can be made by differentiating different thicknesses on the two brake surfaces of the brake band.

[0148] According to a particularly preferred embodiment, the deposition step (d) for forming the base protective coating 30 consists of two or more different deposition stages of particulate chromium carbide on the surface itself for forming the protective coating.

[0149] More specifically, said step (d) of deposition comprises the following stages.

[0150] - A first deposition stage of the particulate material for forming a first layer of the base protective coating 30 directly on the disc.

[0151] - First layer On the base protective coating 30 of Second layer A second deposition stage of the particulate material for creating.

[0152] As will be made clear below, the second finishing layer enables adjustment of the surface finish of the base protective coating 30 .

[0153] By dividing the depositing step (d) into two stages, it becomes possible to distinguish at least the particle size of the particulate material used in the various stages, in particular. As a result, the depositing step (d) becomes more flexible.

[0154] Advantageously, the particulate material deposited in particulate form in the first deposition stage has a larger particle size than the particulate material deposited in the second deposition stage. In particular, the particulate material deposited in particulate form in the first deposition stage has a particle size composed between 30 and 40 μm, and the particulate material deposited in particulate form in the second deposition stage has a particle size composed between 5 and 20 μm.

[0155] By making the base protection coating 30 in two different deposition stages, using a coarser particle size for the formation of the first layer and a finer particle size for the formation of the second layer (having a finishing function), as a function of the subsequent deposition of the surface protection coating 3, it becomes possible to obtain a coating having the required surface finishing characteristics already at the end of the deposition. Such desired surface finishing characteristics can be obtained without the need to perform polishing and / or other surface finishing operations for the coating. The particles deposited in the second stage fill the roughness on the surface of the base layer. Advantageously, the surface finishing level of the coating can be adjusted by adjusting the particle diameter of the particles deposited in the second stage.

[0156] Preferably, Base protection coating the thickness of the first layer of 30 is composed between 2 / 4 and 3 / 4 of the total thickness of the coating, Base protection coating 30 and the thickness of the second layer is composed between 1 / 4 and 2 / 4 of the total thickness of the coating.

[0157] According to a particularly preferred embodiment of the method, the step e) of depositing the particulate material (WC + Fe + Cr + Al) for forming the surface protection coating 3 is composed of two or more different deposition stages of the particulate material on the same surface for forming the protection coating.

[0158] More specifically, the deposition step (e) includes the following steps.

[0159] - A first deposition step of a particulate material for forming a first layer of the coating directly on the base protection coating 30; and

[0160] - A second deposition step of a particulate material for creating First layer on Second layer the surface protection coating 3.

[0161] Preferably, the surface protection layer 3 undergoes a surface finishing step to achieve the desired final degree of roughness.

[0162] Alternatively, Surface protection coating the surface finish of 3 may be obtained by working directly on the deposition method of the coating itself 3.

[0163] More specifically, Base protection coating similar to what is assumed in step d) of the deposition, step (e) of the deposition of the particulate material forming the surface protection coating 3 can also be divided into two or more steps, and in particular, it is possible to distinguish at least the particle size of the particulate material used in the various steps. This makes the deposition step (e) more flexible.

[0164] Advantageously, the particulate material deposited in the first deposition step has a larger particle size than the particulate material deposited in the second deposition step. In particular, the particulate material deposited in the first deposition step has a particle size composed between 30 and 40 μm, and the particulate material deposited in the second deposition step has a particle size composed between 5 and 20 μm.

[0165] Base protection coating Having two different deposition steps using a coarser particle size for forming and a finer particle size for forming the finishing layer SurfaceEmbodiments of the protective coating or surface 3 can obtain a surface protection coating 3 having the necessary surface finishing features already at the end of deposition without the need to perform polishing and / or other surface finishing operations for the coating. The particles deposited in the second stage fill the roughness of the surface of the base layer. Advantageously, Surface protection coating The surface finish level of 3 can be adjusted by adjusting the particle size of the particles deposited in the second stage.

[0166] In particular, by using particles with a particle size of 30 - 40 μm in the first stage and particles with a particle size of 5 - 20 μm in the second stage, the surface protection coating 3 has a surface roughness Ra in the range of 2.0 - 3.0 μm in the finishing layer.

[0167] Preferably, the thickness of the first layer of the surface protection coating 3 is composed between 2 / 4 and 3 / 4 of the total thickness of the coating, and the thickness of the second layer of the surface protection coating 3 is composed between 1 / 4 and 2 / 4 of the total thickness of the coating.

[0168] Overall, by the HVOF, HVAF, or KM deposition techniques of the particle material, the combination of chemical components used, and the multi-stage deposition method, it is possible to obtain a coating with a limited level of surface roughness, particularly adapted to the intended use of the brake disc 1.

[0169] The following comparative tests between discs were conducted.

[0170] A) A grey cast iron disc brake with a "composite" protective coating according to the invention, having a 50 - μm thick base protective coating (Cr3C2 + NiCr) and a 60 - μm thick surface protective coating (WC + Fe + Cr + Al) made by the HVOF technique. The base protective coating was placed on the disc on a soft nitrided layer having a depth of 15 μm and a hardness value higher than 300 HV in microhardness. Soft nitrided layer constitutes an oxide top layer consisting of 5 - μm thick magnetite Fe3O4, Soft nitrided layerThe treatment designed to increase its roughness was applied to the braking surface that had previously received it.

[0171] B) A gray cast iron brake disk with a "composite" protective coating similar to the present invention, directly produced on the disk without providing a soft nitriding layer.

[0172] These two disks were subjected to normal dynamic bench tests (running-in, AK master, and wear).

[0173] Such tests showed that, when the test conditions were equal, the durability disk A according to the present invention was equivalent to disk B in terms of wear.

[0174] Also, from the perspective of tribological behavior (friction, fading, running-in), it was found that, if the test conditions were the same, the performance of the disk according to the present invention was substantially equivalent to that of the conventional disk B.

[0175] Also, the two disks were subjected to a series of resistance tests in the presence of complex and environmental thermomechanical stresses.

[0176] As described above, such tests showed that the performance of the disk according to the present invention was superior to that of disk B in terms of strength in the presence of environmental stresses (thermomechanical shock and corrosive agents).

[0177] More specifically, the two disks were subjected to a test program assuming repeated composite dynamic bench tests (the disks were each subjected to different braking cycles with a plurality of consecutive braking operations) and tests in a corrosive environment (salt spray and dew condensation tests: the disks and brake pads were placed in a high humidity environment with salt spray and high temperature excursions).

[0178] At the end of a predetermined number of repetitions, B showed overall peeling of the protective coating, while disk A had only minimal local peeling of the protective coating.

[0179] As can be understood from the above description, the disc brake and its manufacturing method according to the present invention can overcome the drawbacks of the prior art.

[0180] In fact, the brake disc manufactured according to the present invention is either not exposed to flaking or is exposed to a much lesser extent than known solutions (to ensure wear resistance over time), and at the same time, it does not contain cobalt.

[0181] The brake disc coated with the nitrocarburized layer according to the present invention showed similar wear resistance and tribological behavior under normal environmental conditions compared to a similar coated disc without the nitrocarburized layer.

[0182] Also, the brake disc coated according to the present invention was found to have the best performance in terms of strength in the presence of environmental stresses (thermal shock and salt damage).

[0183] Also, the brake disc 1 generally has a low manufacturing cost.

[0184] Those skilled in the art can make numerous changes and modifications to the above-mentioned disc and brake disc within the scope of protection defined by the following claims to meet occasional specific needs.

[0185] According to a general embodiment, a brake band 2 for the disc of the disc brake 1 is provided.

[0186] The brake band 2 extends between an inner diameter D1 close to the rotation axis X-X of the brake band 2 and an outer diameter D2 far from the rotation axis X-X. The rotation axis defines the axial direction X-X.

[0187] The brake band 2 defines a radial direction R-R that is substantially orthogonal to the axial direction X-X and a circumferential direction C-C that is orthogonal to both the axial direction X-X and the radial direction R-R.

[0188] According to a general embodiment, the brake band 2 of the disk brake disk 1 is composed of an annular band body 6 arranged around the brake disk rotation axis, that is, the brake disk rotation axis X-X.

[0189] The band body 6 is made of gray cast iron or steel or aluminum or their alloys.

[0190] The brake band 2 consists of at least one brake surface 2a or 2b.

[0191] At least a part of the at least one brake surface 2a or 2b is for activating Band body part 7 to increase the adhesion ability of at least one protective surface coating 3 arranged on the surface of Band body part 7 and is composed of

[0192] The Surface protection coating 3 consists of at least one material having increased resistance to wear.

[0193] The activation Band body part 7 is arranged on the surface of the band body 6 and forms the outermost layer of the brake band 2 together with the at least one protective surface coating 3.

[0194] The activation Band body part 7 constitutes a rough profile 8.

[0195] The rough profile 8 includes at least one Channel or groove 9 delimited by at least one pair of protrusions 10 and / or 11 and / or 12.

[0196] The at least one Groove 9 extends along a path that at least partially surrounds the rotation axis X-X.

[0197] The at least one Groove 9, in a cross-section in its longitudinal extension,Groove has a bottom 13 and two opposing Groove sides 14, 15.

[0198] Advantageously, the first Groove side 14 forms an acute angle a1, i.e., an angle a1 less than 90 degrees, with the said Groove bottom 13. The second Groove side 15 forms an obtuse angle a2, i.e., an angle a2 greater than 90 degrees, with the said Groove bottom 13.

[0199] According to an embodiment, the first and second Groove sides 14, 15 are parallel to each other.

[0200] According to an embodiment, the first Groove side 14 forms an acute angle of 80 degrees a1 with the said Groove bottom 13.

[0201] According to an embodiment, the second Groove side 15 forms an obtuse angle (a2) of 100 degrees with the said Groove bottom 13.

[0202] According to an embodiment, the protrusion is a first protrusion 10 that forms undercuts 17 on both sides of the protrusion.

[0203] According to an embodiment, the protrusion is a second protrusion 11 that forms an obtuse angle a2 with the respective Groove bottom 13 and partitions the Groove side 15.

[0204] According to an embodiment, the protrusion Groove is a first Groove side 14 that forms an acute angle a1 with the bottom 15, and Groove is a third protrusion 12 that forms an obtuse angle a2 with the Opposite second groove side bottom 13 and partitions the 13.

[0205] According to an embodiment, the at least one pair of protrusions 10 and / or 11 and / or 12 are, in particular, a plurality of protrusions 20 that alternately arrange the first protrusion 10 and the second protrusion 11.

[0206] According to an embodiment, the at least one set of protrusions 12 are all equal plurality of protrusions 20, in particular, a plurality of third protrusions 12.

[0207] According to an embodiment, the at least one set of protrusions 11 and / or 12 are a plurality of protrusions 20,

[0208] - a first plurality of third protrusions 12,

[0209] - a second plurality of third protrusions 12, wherein the cross-section of the second plurality of protrusions in their longitudinal extension, i.e., the profile, is opposite to the profile of the first plurality of protrusions; and

[0210] - a second protrusion 11 interposed between the first and second pluralities.

[0211] According to an embodiment, the at least one Groove 9s are installed side by side, separated by a first protrusion 10 disposed between the pair of Groove 9s, and the protrusion forms an acute angle a1 with the Groove 9 at both of its opposing edges and with the Groove side surface 14, and with both the Groove bottom 13.

[0212] According to an embodiment, the at least one Groove 9s are installed side by side, and are a first pair of Groove 9s partitioned by a first protrusion 10 disposed between the pair of Groove 9s; the protrusion partitions the side surface 14 at both of its opposite edges, forming an undercut Groove portion 17, i.e., a deep cavity, Groove and Groove bottomIt forms an acute angle a1 with the constituent plane of 13.

[0213] According to an embodiment, the at least one Groove 9 are arranged side by side, and are separated by a second protrusion 11 disposed between the Groove 9. 、 The protrusion, at both of its opposing edges, Groove separates the side surfaces 15, and both form an obtuse angle a2 with the Groove bottom 13.

[0214] According to an embodiment, the at least one Groove 9 are arranged side by side, and are partitioned by the Groove disposed between the side-by-side arranged Third protrusion 12 ; Groove and is The third protrusion 12 at both of its opposite edges Groove separates the side surfaces 14, 15 Having , the first side surface 14 forms an acute angle a1 with the Groove bottom surface 13, and the second side surface 15 forms an obtuse angle a2 with the Groove bottom surface 13.

[0215] According to an embodiment, the third protrusion 11 forms side surfaces 14, 15 that are parallel to each other and face the side-by-side arranged Groove 9 on both of its sides. Groove

[0216] According to an embodiment, the third protrusion 11 that forms the first side surface 14 having an acute angle a1 with respect to the channel bottom 13 has the first side surface 14 inclined and forms an undercut 17 that faces or is directed towards the rotation axis X-X.

[0217] According to an embodiment, the Groove third protrusion that forms the first side surface 14 having an acute angle a1 with respect to the 12 bottom 13 forms an undercut 17 where the first side surface 14 is inclined and faces away from the rotation axis X-X or faces the rotation axis X-X.

[0218] According to an embodiment, the activation band main body 7 is composed of two brake band portions formed on the same brake band 2; here

[0219] Only the third protrusion 11 having side surfaces 14 and 15 parallel to each other is formed in the first portion, and the Groove The first side surface 14 having an acute angle a1 with respect to the bottom 13 is inclined to form an undercut 17 facing or directed towards the rotation axis X-X.

[0220] The third protrusion 11 having side surfaces 14 and 15 parallel to each other is formed in the second portion, and the Groove Forming the first side surface 14 having an acute angle a1 with respect to the bottom 13 is characterized in that the first side surface 14 is inclined to form an undercut 17 facing or pointing to the side opposite to the rotation axis X-X.

[0221] According to the embodiment, the first protrusion 10 that forms undercuts 17 on both sides and the second protrusion 11 that forms a channel bottom 13 and an obtuse angle a2 on both sides are alternately arranged in the rough profile 8 to form a groove 9 between these protrusions 10, 11.

[0222] According to an embodiment, the Groove 9 has a depth of 0.05 mm to 0.1 mm, preferably 0.075 mm, and a width consisting of 0.5 mm to 0.7 mm.

[0223] According to an embodiment, the protrusion 10 or 11 or 12 has a width substantially the same as the width of the Groove 9.

[0224] According to an embodiment, the Groove The bottom 13 is a substantially flat surface.

[0225] According to an embodiment, the protrusion 10 or 11 or 12 is delimited externally by a protrusion ridge 18, and the protrusion ridge 18 is a substantially flat surface.

[0226] According to an embodiment, the protrusion 10 or 11 or 12 is delimited externally by a protrusion ridge 18, and the GrooveThe side surfaces 14 and 15 are joined to the protruding ridge with a connection radius of 0.1 mm to 0.4 mm.

[0227] According to an embodiment, the Groove side surfaces 14 and 15 are joined to the Groove bottom 13 at a connection portion, and the connection portion has a connection radius ranging from 0.01 mm to 0.02 mm.

[0228] According to an embodiment, the band body 6 is formed of a base material selected from gray cast iron or steel, where

[0229] - The at least one activated Band body part covering 7 is Base protection coating 30, and the Base protection coating 30 is formed of chromium carbide Cr3C2 and nickel chromium NiCr, or nickel chromium NiCr, iron Fe, molybdenum Mo, cobalt Co, manganese Mn, and aluminum Al, and is obtained by depositing using a thermal spraying technique, preferably the High-Velocity Oxygen Fuel (HVOF) technique, or the High-Velocity Air Fuel (HVAF) technique or the Kinetic Metallization (KM) technique, and

[0230] - The at least one activated Band body part protective surface coating 3 covering 7, where the protective surface coating 3 is formed of tungsten carbide WC, iron Fe, chromium Cr, and aluminum Al, Base protection coating and is obtained by depositing particulate forms of tungsten carbide WC, iron Fe, chromium Cr, and aluminum Al onto 30 using a spray deposition method, preferably the high-velocity oxygen fuel of the HVOF method, or the high-velocity air fuel of the HVAF method, or the Kinetic Metallization of the KM method.

[0231] And the at least one activated Base protection coating covered by 3 Band body partThe surface of 7 is defined by the soft nitrided layer 300 of the base metal and has a rough profile in a radial or circumferential cross-section with respect to the center of the brake band.

[0232] The present invention further relates to a disc brake disc 1 comprising a brake band 2 defined by any one of the embodiments described above and a bell 5 associated with the brake band 2 and configured to be connected to a wheel hub of a vehicle.

[0233] The present invention further relates to a vehicle comprising the disc brake disc 1 as described above.

[0234] A method for obtaining a brake band according to the present invention will be described below.

[0235] The manufacturing method 2 of the brake band includes the following operation steps.

[0236] - Providing a brake band 2 including at least one brake surface 2a or 2b, the brake band 2 being made of a band body 6 of gray cast iron or steel or aluminum or an alloy thereof.

[0237] - Subjecting at least a part of the at least one brake surface 2a or 2b to a process configured to increase its surface roughness by machining by chip removal or by laser engraving or by plastic deformation, to form the activated Band body part 7.

[0238] - Generating the activated Band body part 7 on the surface of the band body 6 to create a rough profile 8.

[0239] - Creating the rough profile 8 having at least one Channel or groove 9 defined by at least a pair of protrusions 10 and / or 11 and / or 12.

[0240] - The at least one Groove Step of extending the 6 along a path that at least partially surrounds the rotation axis X-X.

[0241] - The at least one Groove 6 such that its cross-section in its longitudinal extension is Groove bottom 13 and two opposing Groove Side surfaces 14, 15.

[0242] - The Groove First side surface 14 is made so as to form an acute angle a1, i.e., an angle a1 smaller than 90 degrees, with the bottom 13. Groove Step of making the first side surface 14.

[0243] - The second Groove Side surface 15 is made so that it forms an obtuse angle a2 with the bottom 13, i.e., an angle a2 larger than 90 degrees. Groove Step of making the second side surface 15.

[0244] - At least one protective coating 3 and / or 30 and / or 300 and / or 330 made of at least one material having increased resistance to wear is deposited on the activated Band body part 7.

[0245] According to a further embodiment of the method, the following further step of soft nitriding the surface layer 300 on the surface of the activated Band body part 7 is configured.

[0246] The Soft nitrided layer Step of depositing, in particulate form, a material composed of chromium carbide Cr3C2 and nickel chromium NiCr, or nickel chromium NiCr, iron Fe, molybdenum Mo, cobalt Co, manganese Mn, aluminum Al, on the 300.

[0247] Using a spraying deposition technique, preferably HVOF (High-Velocity Oxygen Fuel), or HVAF technique (High-Velocity Air Fuel), or KM technique (Kinetic Metallization), with the soft nitrided layer 300 interposed, the active Band body part surface of 7 is covered Base protection coating to form 30.

[0248] The Base protection coating On 30, a particulate material composed of tungsten carbide WC, iron Fe, chromium Cr, and aluminum Al is deposited using a spraying deposition method, preferably HVOF (High-Velocity Oxygen Fuel), or HVAF technique (High-Velocity Air Fuel), or KM technique (Kinetic Metallization), to form a protective surface coating 3 composed of tungsten carbide WC, iron Fe, chromium Cr, and aluminum Al and covering the surface of the active band body part 7.

[0249] The present invention relates to a tool 21 for manufacturing the activated Band body part 7, which includes at least one cutting edge 22, and this cutting edge 22 has a rough profile that defines at least one cutting edge projection 23 having at least one cutting edge ridge 24, a first cutting edge side 25, and a second cutting edge side 26.

[0250] The Cutting edge ridge 24 is evaluated parallel to, and the Cutting edge edge has a maximum Groove cutting edge projection width 27 smaller than the maximum width 16.

[0251] According to an embodiment, the tool 21 is composed of a plurality of cutting edge protrusions 28 arranged side by side.

Explanation of Reference Numerals

[0252] 1 Brake disc 2 Brake band 2a Opposing brake surfaces 2b Opposing brake surfaces 3 Surface protection coating 300 Nitrocarburized layer 330 Oxidized surface layer 4 Annular part or fixed part 5 Connecting element or bell 6 Band body 7 Activated band body part 8 Rough surface shape 9 Groove 10 First protrusion forming undercuts on both sides 11 Second protrusion: Separates the side surface of the groove, which forms an obtuse angle with the bottom surface of the groove 12 Third protrusion: The first Groove Side surface forming an acute angle with the channel bottom surface, and Groove Defines the second opposite channel side surface forming an obtuse angle with the bottom surface 13 Channel bottom surface 14 The Groove Side surface forming an acute angle with the bottom surface First groove Side surface 15 The Groove Side surface forming an obtuse angle with the bottom surface Second groove Side surface 16 Maximum Groove Width 17 Undercut 18 Protrusion Ridge 20 Multiple protrusions 21 Tool 22 Cutting edge 23 Cutting edge protrusion 24 Cutting edge ridge line 25 First surface of the cutting edge 26 Second surface of the cutting edge 27 Cutting edge Edge Protrusion Maximum width 30 Protective film A - A Rotation axis of the brake band or brake disc X - X Rotation axis or axial direction R - R Radius Direction C - C Tangential direction D1 Diameter of the inner ring Outer diameter of D2 band

Claims

1. A brake band (2) for a disk of a disk brake (1), wherein the brake band (2) includes an annular band body (6) arranged around the rotation axis (X-X) of the brake disk, the band body (6) is made of gray cast iron or steel or aluminum or an alloy thereof, the brake band (2) has at least one brake surface (2a or 2b), at least a part of the at least one brake surface (2a or 2b) is an activated band body part (7) including a band body part (7) for increasing the adhesion ability of a surface protection coating (3) arranged on the surface of the band body part (7), the surface protection coating (3) includes at least one material with increased resistance to wear, the band body part (7) is arranged on the surface of the band body (6) so as to form the outermost layer of the brake band (2) with the surface protection coating (3), the band body part (7) includes a rough profile (8), the rough profile (8) includes a channel or groove (9) partitioned between at least two protrusions, the groove (9) extends along a path that at least partially surrounds the rotation axis (X-X), the groove (9) has two groove side surfaces including a groove bottom (13) and a first groove side surface (14) and a second groove side surface (15) facing each other across the groove bottom (13) in a cross section in the longitudinal extension of the groove (9), the first groove side surface (14) forms an acute angle (a1), that is, an angle (a1) smaller than 90 degrees, with the groove bottom (13), the second groove side surface (15) forms an obtuse angle (a2), that is, an angle (a2) larger than 90 degrees, with the groove bottom (13), the brake band (2).

2. The at least two protrusions have two protrusions, one of the two protrusions (10) has the first groove side surface (14) facing the other protrusion (11) of the two protrusions on one side of the one protrusion (10), the other protrusion (11) of the two protrusions has the second groove side surface (15) facing the one protrusion (10) on one side of the other protrusion (11), the brake band (2) according to Claim 1.

3. The at least two protrusions have two protrusions, One of the two protrusions, i.e., protrusion (10), has the first groove side surfaces (14) on both sides of the one protrusion (10), The other protrusion (11) of the two protrusions has the second groove side surface (15) on one side facing the one protrusion (10). The brake band (2) according to claim 1. **Claim 4**: The brake band (2) according to any one of claims 1 to 3, wherein the first groove side surface (14) and the second groove side surface (15) extend parallel to each other. **Claim 5**: The at least two protrusions have a plurality of first protrusions (10) and a plurality of second protrusions (11), The plurality of first protrusions (10) and the plurality of second protrusions (11) are arranged such that the first protrusions (10) and the second protrusions (11) are alternately arranged, The first protrusion (10) forms the first groove side surfaces (14) on both sides of the first protrusion (10), The two first groove side surfaces (14) formed on both sides of the first protrusion (10) form the acute angle (a1) with the groove bottom (13), and the acute angle (a1) defines an undercut (17), The first protrusion (11) forms the second groove side surfaces (15) on both sides of the first protrusion (11), The two second groove side surfaces (15) formed on both sides of the second protrusion (11) form the obtuse angle (a2) with the groove bottom (13). The brake band (2) according to claim 1. **Claim 6**: The at least two protrusions have a plurality of third protrusions (12), The plurality of third protrusions (12) are arranged adjacent to each other in parallel, Each of the plurality of third protrusions (12) has the first groove side surface on one side of the third protrusion (12) and the second groove side surface on the other side of the third protrusion (12), The first groove side surface forms the acute angle (a1) with the groove bottom (13), The second groove side surface forms the obtuse angle (a2) with the groove bottom (13). The brake band (2) according to claim 1. **Claim 7**: The at least two protrusions have a second protrusion (11) and two third protrusions (12) located on both sides of the second protrusion (11), The second protrusion forms the second groove side surfaces (15) on both sides of the second protrusion, The second groove side surface (15) forms the obtuse angle (a2) with the groove bottom (13), The two third protrusions (12) have a first third protrusion (12) and a second third protrusion (12), The first third protrusion and the second third protrusion each form the first groove side surface on the side close to the second protrusion (11), and form the second groove side surface on the opposite side away from the second protrusion (11). The first groove side surface forms the acute angle (a1) with the groove bottom (13). The second groove side surface forms the obtuse angle (a2) with the groove bottom (13). The brake band (2) according to claim 1. **Claim 8**: The first groove side surface of the third protrusion (12) is arranged on the side facing the rotation axis or on the side opposite to the rotation axis, and forms an undercut with the groove bottom (13). The brake band (2) according to claim 6 or 7. **Claim 9**: The acute angle (a1) is 80 degrees, and / or The obtuse angle (a2) is 100 degrees. The brake band (2) according to any one of claims 1 to 8. **Claim 10**: The groove (9) has a depth of 0.05 mm to 0.1 mm. The brake band (2) according to any one of claims 1 to 9. **Claim 11**: The at least two protrusions have a width equal to the width of the groove (9). The brake band (2) according to any one of claims 1 to 10. **Claim 12**: The groove bottom (13) is a flat surface. The brake band (2) according to any one of claims 1 to 11. **Claim 13**: The at least two protrusions are externally separated by a protrusion ridge (18), and the protrusion ridge (18) is a flat surface. Or, The at least two protrusions are externally separated by a protrusion ridge (18). The first groove side surface (14) and the second groove side surface (15) are joined to the protrusion ridge (18) with a connection radius of 0.1 mm to 0.4 mm. The brake band (2) according to any one of claims 1 to 12. **Claim 14**: The first groove side surface (14) and the second groove side surface (15) are joined to the protrusion ridge (18) with a connection radius of 0.01 mm to 0.02 mm. The brake band (2) according to claim 13. **Claim 15**: The band body (6) is formed of a base metal selected from gray cast iron or steel. - A base protection coating (30) covering the at least one band body portion (7). Chromium carbide (Cr 3 C 2 ) and nickel chromium (NiCr), or formed by nickel chromium (NiCr), iron (Fe), molybdenum (Mo), cobalt (Co), manganese (Mn) and aluminum, a base protection coating (30) obtained by film formation using a thermal spraying film formation technique, namely HVOF technique (High Velocity Oxygen Fuel), HVAF technique (High Velocity Air Fuel) or KM technique (Kinetic Metallization), - a surface protection coating (3) covering the band main body portion (7), formed by tungsten carbide (WC), iron (Fe), chromium (Cr) and aluminum, having a surface protection coating (3) obtained by forming tungsten carbide (WC), iron (Fe), chromium (Cr) and aluminum in particle form on the base protection coating (30) using a thermal spraying deposition technique, namely HVOF technique (High Velocity Oxygen Fuel), HVAF technique (High Velocity Air Fuel) or KM technique (Kinetic Metallization), the surface of the band main body portion (7) coated with the base protection coating (3) is defined by the nitrocarburized layer (300) of the base metal and has a rough profile in a radial or circumferential cross section with respect to the center of the brake band, The brake band (2) according to claim 1.

16. A disk of a disc brake (1) including the brake band (2) defined by any one of claims 1 to 15 and a bell (5) associated with the brake band (2) and configured to be connected to a hub of a wheel of a vehicle.

17. A vehicle including the disk for the disc brake (1) according to claim 16.

18. - Providing a brake band (2) including at least one brake surface (2a or 2b), the brake band (2) being made using a band body (6) of gray cast iron or steel or aluminum or an alloy thereof, - subjecting at least a part of the at least one braking surface (2a or 2b) to a treatment for increasing its surface roughness by treatment by removal of swarf, treatment by laser engraving, or treatment by plastic deformation, and forming a band body portion (7); - generating the band body portion (7) on the surface of the band body (6) to create a rough profile (8); - forming at least one groove (9) in the rough profile (8), delimited by at least one pair of protrusions (10 and / or 11 and / or 12); - extending the at least one groove (9) along a path that at least partially surrounds the axis of rotation (X-X) of the brake band (2); - including the step of making the at least one groove (9) such that a cross-section in its longitudinal extension consists of a groove bottom (13) and two opposing first groove side surfaces (14) and second groove side surfaces (15); - the first groove side surface (14) is made such that the first groove side surface (14) forms an acute angle (a1), i.e., an angle (a1) smaller than 90 degrees, with the groove bottom (13); - the second groove side surface (15) is made such that the second groove side surface (15) forms an obtuse angle (a2) with the groove bottom (13), i.e., an angle (a2) larger than 90 degrees; - further including the step of depositing at least one protective coating (3 and / or 30 and / or 300 and / or 330) made of at least one material having high wear resistance on the band body portion (7), a method for manufacturing a brake band (2).

19. subjecting the band body portion (7) to nitrocarburizing to obtain a nitrocarburized surface layer (300) on the surface of the band body portion (7); on the nitrocarburized surface layer (300), using HVOF (High Velocity Oxygen Fuel), HVAF technology (High Velocity Air Fuel) or KM technology (Kinetic Metallization), which are thermal spraying film-forming technologies, in particulate form, - chromium carbide (Cr₃C₂) and nickel chromium (NiCr), or - nickel chromium (NiCr), iron (Fe), molybdenum (Mo), cobalt (Co), manganese (Mn) and aluminum (Al) Depositing to form a base protection coating (30) that covers the surface of the band main body (7) with the nitrocarburized surface layer (300) interposed therebetween; A particulate material composed of tungsten carbide (WC), iron (Fe), chromium (Cr), and aluminum (Al) is deposited on the base protection coating (30) using a thermal spraying deposition method such as HVOF (High Velocity Oxygen Fuel), HVAF method (High Velocity Air Fuel), or KM method (Kinetic Metallization) to form a surface protection coating (3) composed of tungsten carbide (WC), iron (Fe), chromium (Cr), and aluminum (Al) that covers the surface of the band main body (7). The method for manufacturing a brake band (2) according to claim 18, comprising the steps of:

20. A tool (21) for manufacturing an activated band main body (7), Including at least one cutting edge (22), The at least one cutting edge (22) has a rough profile defining at least one cutting edge protrusion (23) having at least one cutting edge ridge (24), a first cutting edge side (25), and a second cutting edge side (26), The cutting edge has a maximum cutting edge protrusion width (27) smaller than the maximum groove width (16). The tool (21).

21. The tool (21) according to claim 20, including a plurality of cutting edge protrusions (28) arranged side by side.

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