Improved components for chassis assemblies of tracked vehicles, chassis and endless tracks comprising such improved components and methods for producing improved components for chassis assemblies

Abstract

This invention relates to an improved component (53) of a chassis assembly (1) for a tracked vehicle. The chassis assembly (1) includes a chassis frame assembly (3) to which a track (5) can be assembled for movement relative to the chassis frame assembly (3). The chassis assembly (1) also includes a first friction surface (7, 540) and a second friction surface (9, 560) configured to slide against each other. The first friction surface (7) and the second friction surface (9) are formed by the chassis frame assembly (3) and / or the track (5). The improved component (53) is incorporated in the chassis frame assembly (3) or the track (5) and at least forms the first friction surface (7). The first friction surface (7) is made of a hard coating obtained by an EHLA coating process.

Description

Technical Field

[0001] The present invention relates to improved wear-resistant components for tracked vehicles (such as bulldozers, excavators, loaders, excavators, dump trucks, road pavers, mobile drilling rigs, agricultural tractors, and military tanks), and a method for manufacturing said improved wear-resistant components. Background Technology

[0002] The continuous metal tracks of tracked earthmoving machinery typically include multiple bushings, each of which is axially passed through by a pin. The pin laterally connects two main track links that are generally arranged side by side and hinges two subsequent main track links together, thereby forming a hinged chain of multiple track links.

[0003] During operation, the outer wing of the bushing slides against the teeth of the sprocket on the chassis and is subjected to stress caused by particularly severe wear.

[0004] The inner wing of the bushing is also subjected to stress caused by wear due to friction with their respective pins.

[0005] Intermittent contact and sliding between the bushing and the teeth can exacerbate wear damage to the bushing and lead to fatigue stress, so these bushings need to have sufficient toughness.

[0006] These wear and fatigue stresses are among the most severe, and bushings are among the shortest-lived components in the chassis.

[0007] To withstand these stresses, the bushing material must be selected with extreme care, and currently the bushings undergo specific heat treatments and / or chemical treatments. These treatments are time-consuming and costly.

[0008] For example, in known manufacturing methods, the bushing undergoes extrusion molding, carburizing, and finally quenching and tempering.

[0009] The object of the present invention is to overcome the above-mentioned disadvantages, and in particular to provide a bushing or another chassis component that can withstand wear and other mechanical stresses, even when obtained by a manufacturing method that is simpler and / or less expensive than known processes. Summary of the Invention

[0010] According to a first aspect of the invention, the scope of protection is achieved by an improved component for a chassis assembly of a tracked vehicle, the improved component having the features according to claim 1.

[0011] Ultra-high speed laser cladding (EHLA) treatment only allows for increasing the hardness of worn areas of the bushings of continuous tracks—or other modified chassis components—avoiding hardening of other areas that are unaffected by wear or where wear is negligible.

[0012] These coating processes can be performed at or near the end of the manufacturing process of bushings or other improved components because they do not substantially change the size, shape, and hardness of the coated substrate.

[0013] More specifically, these coating processes can be advantageously performed after the heat treatment and machining of the bushing, or more generally, at the end or near the end of the manufacturing process of bushing 53 or another improved component.

[0014] In this way, if certain manufacturing steps are performed by external suppliers, the semi-finished parts need to be handled less often, such as when being packaged and unpacked upon delivery to or by external suppliers; in addition, the main manufacturer's production line needs to change tooling less often, or even not at all.

[0015] In an improved component according to a specific embodiment of the present invention, the hard coating has one or more of the following elements by weight: - The carbon content is between 0.5-5.0 wt%; - Chromium content is between 5.0-30 wt%; - The nickel content is between 2.0-15 wt%; - The silicon content is between 0.5-10 wt%; - The boron content is between 1.0-20 wt%; - The iron content balances the content of one or more of the aforementioned elements to 100%.

[0016] In the improved component according to a specific embodiment of the present invention, the hard coating has all the following elements by weight: - The carbon content is between 0.5-5.0 wt%; - Chromium content is between 5.0-30 wt%; - The nickel content is between 2.0-15 wt%; - The silicon content is between 0.5-10 wt%; - The boron content is between 1.0-20 wt%; - The iron content balances the content of the aforementioned elements to 100%.

[0017] In an improved component according to a specific embodiment of the present invention, the hard coating has one or more of the following elements by weight: - The carbon content is between 1.0 and 3.5 wt%; - Chromium content is between 10-18 wt%; - The nickel content is between 3.5-10 wt%; - The silicon content is between 1.0 and 5.0 wt%; - The boron content is between 2.5-8.0 wt%.

[0018] In an improved component according to a specific embodiment of the present invention, the hard coating has one or more of the following elements by weight: - The carbon content is between 2.0-2.5 wt%; - The chromium content is between 13-14 wt%; - The nickel content is between 5.5-6.5 wt%; - The silicon content is between 2.0-2.5 wt%; - The boron content is between 3.5-4.0 wt%.

[0019] In the improved component according to a specific embodiment of the present invention, the hard coating has all the following elements by weight: - The carbon content is between 2.0-2.5 wt%; - The chromium content is between 13-14 wt%; - The nickel content is between 5.5-6.5 wt%; - The silicon content is between 2.0-2.5 wt%; - The boron content is between 3.5-4.0 wt%; - The iron content balances the content of the aforementioned elements to 100%.

[0020] In an improved component according to a specific embodiment of the present invention, the hard coating comprises one or more of the following materials: tungsten carbide, molybdenum boride, vanadium carbide, martensitic steel, nickel or nickel alloy, cobalt or cobalt alloy, and chromium carbide.

[0021] In an improved component according to a specific embodiment of the present invention, the hard coating has one or more of the following substances: - The tungsten carbide content is between 0-50 wt%; - The content of cobalt, cobalt alloy, nickel or nickel alloy is between 0-30 wt%; - The content of molybdenum boride or chromium carbide is between 0-40 wt%; - The content of martensitic steel is between 40-99 wt%; - The content of molybdenum boride or chromium carbide is between 0-40 wt%; - The vanadium carbide content is between 0-40 wt%.

[0022] In an improved component according to a specific embodiment of the present invention, the hard coating has one or more of the following substances: - The tungsten carbide content is between 5-45 wt%; - The content of cobalt, cobalt alloy, nickel or nickel alloy or martensitic steel is between 10-14 wt%. - The content of molybdenum boride or chromium carbide is between 5-15 wt%; - The content of martensitic steel is between 50-90 wt%; - The vanadium carbide content is between 5-30 wt%.

[0023] In an improved component according to a specific embodiment of the present invention, the titanium content of the hard coating is between 1.0-8.0 wt%, more preferably between 2.0-7.0 wt% or between 4.0-5.0 wt%.

[0024] Due to the aforementioned components, the hard coating exhibits high hardness and wear resistance, for example, reducing wear on the substrate by approximately 70%. This percentage was obtained from testing improved components of the chassis assembly under design conditions, particularly corresponding to the number of hours or cycles of the component under design conditions.

[0025] In an improved component according to a specific embodiment of the present invention, the hardness of the hard coating is between 50 and 100 HRC.

[0026] The prior hardness value allows metal bushings, for example, connecting different track links of a continuous track, to effectively withstand wear caused by engagement with sprockets of the chassis components of a tracked vehicle or more generally, while reducing the manufacturing cost of the bushings themselves.

[0027] The service life of this bushing is significantly improved.

[0028] In an improved component according to a specific embodiment of the present invention, the hardness of the hard coating is between 60 and 80 HRC.

[0029] These hardness values ​​represent a more ideal balance between wear resistance and reduced manufacturing costs.

[0030] In an improved component according to a specific embodiment of the invention, the average thickness of the hard coating is between 0.1 and 1 mm.

[0031] This thickness selection is particularly effective in simultaneously improving wear resistance and maintaining low manufacturing costs.

[0032] In an improved component according to a specific embodiment of the present invention, the hard coating obtained by the ultra-high-speed laser cladding, also known as EHLA, has one or more of the following characteristics: - Surface roughness Rz is less than or equal to 300 micrometers; - Surface roughness Rz is less than or equal to 23 micrometers; - Surface roughness Ra is less than or equal to 50 micrometers; - Surface roughness Ra is less than or equal to 6 micrometers.

[0033] These relatively low surface roughness values, obtainable through a relatively fast and inexpensive EHLA process, further improve the wear resistance of the hard coating and the first friction surface, thereby further reducing substrate wear.

[0034] An improved component according to a specific embodiment of the present invention includes a base coated with a hard coating, the base comprising a substrate selected from the group consisting of: - Steel that has not been pre-carburized or surface-hardened; - Steel with a carbon content of less than or equal to 0.5 wt%, or less than or equal to 0.45 wt%, or less than or equal to 0.30 wt%; - Steel with a carbon content between 0.1-0.5 wt%; - Steel with a carbon content between 0.4 and 0.45 wt%.

[0035] Avoiding carburizing or surface hardening steps can reduce the time and cost of manufacturing bushings for continuous tracks or other improved chassis components.

[0036] An improved component according to a specific embodiment of the present invention is a bushing (53).

[0037] In an improved component according to a specific embodiment of the present invention, the base has a generally tubular shape.

[0038] In an improved component according to a specific embodiment of the present invention, the base is formed at least by extrusion molding.

[0039] In a second aspect of the invention, the above-mentioned protection scope is achieved by a chassis assembly having the features described in claim 14.

[0040] In a third aspect of the invention, the above-mentioned scope of protection is achieved by a continuous track having the features described in claim 15.

[0041] In a continuous track according to a specific embodiment of the present invention: - The continuous track (5) includes multiple track links, multiple articulated pins 52 and multiple pin bushings (53); - Each track link includes a corresponding hinge pin (52) and a corresponding pin bushing (53), which are fixed and hinged to subsequent track links by the corresponding hinge pin (52); - Each hinge pin (52) passes axially through the corresponding pin bushing (53); - Each pin bushing (53) forms a side wing; - The chassis frame assembly (3) includes at least one sprocket (32, 34) configured to engage the hinge pin (52), abut against the side wing of the pin bushing (53) and / or slide against the side wing; - At least a portion of, or all of, of the plurality of pin bushings (53) have the features described in claim 11.

[0042] In a fourth aspect of the invention, the above-mentioned scope of protection is achieved by a method for producing an improved component of a chassis assembly having the features described in claim 17.

[0043] Avoiding carburizing or surface hardening of the entire pin bushing of continuous tracks or other modified chassis components simplifies the manufacturing process and reduces its cost; this advantage is particularly significant because carburizing and surface hardening are thermochemical processes, which are specialized manufacturing processes that require special and expensive systems, equipment and facilities.

[0044] In summary, avoiding carburization or surface hardening significantly reduces manufacturing costs, thereby improving—or at least not worsening—the performance of the improved chassis components.

[0045] The dependent claims relate to other features of the invention.

[0046] The advantages that can be realized by the present invention will become more apparent to those skilled in the art from the following detailed description of specific and non-limiting embodiments illustrated in the following schematic diagrams. Attached Figure Description

[0047] Figure 1 A perspective view of a chassis assembly according to a specific embodiment of the present invention is shown; Figure 2 It shows Figure 1 A perspective view of a portion of the continuous track of the chassis assembly; Figure 3 It shows Figure 2 A cross-sectional view of a portion of a continuous track, the cross-section being a section along the axis passing through the pin; Figure 4 It shows Figure 2 A three-dimensional view of the pin bushings of a continuous track; Figure 5It shows Figure 4 A cross-sectional view of a portion of the center pin bushing, the cross-section being a section based on the shaft passing through the pin; Figure 5A It shows Figure 5 Magnified details; Figure 6 It shows Figure 1 A three-dimensional view of a portion of the sprocket of the chassis component. Detailed Implementation

[0048] Figure 1-6 A chassis assembly according to a specific embodiment of the present invention is generally referenced as 1.

[0049] The chassis component 1 can be a component of a tracked vehicle (such as a bulldozer, excavator, loader, mining machine, dump truck, road paver, mobile drilling rig, agricultural tractor, or military tank).

[0050] The chassis assembly 1 includes a chassis frame assembly 3, and the tracks 5 can be assembled onto the chassis frame assembly so as to be able to move relative to the chassis frame assembly 3.

[0051] The track 5 may include multiple track links, each track link including, for example, a track link body 50 and a track plate 51 fixed to the track link body. The track links may be hinged together to form a chain, preferably a self-closing continuous chain. Figure 1 , 2 In this case, the tracks are preferably and primarily made of steel or another metal material.

[0052] Preferably, the track 5 includes a plurality of pin assemblies that connect a first track link to a second track link and subsequent track links; for example, each pin assembly can connect and hinge to the first and second track link bodies 50, which are portions of the first and second track links and subsequent track links, respectively. Figure 2 ).

[0053] Each pin assembly may include a hinge pin 52 and a pin bushing 53.

[0054] For example, track links can be assembled and hinged together by pressing the two opposite ends of each hinge pin 52 into two pin holes formed in the ends of the link bodies 50 of adjacent track links to prevent the hinge pins 52 from rotating relative to the link bodies 50 of adjacent track links; in this way, each hinge pin 52 is laterally connected to the link bodies 50 of the track links.

[0055] Preferably, each end of the pin bushing 53 is press-fitted into the bushing holes at both ends of the two corresponding track links.

[0056] Since the hinge pin 52 extends axially through and out of its respective pin bushing 53 and is rotatable relative to the bushing 53, each pin assembly connects and hinges two adjacent track links.

[0057] The wall of pin bushing 53 may have a maximum radial thickness WBS, for example, between 5 and 50 mm and a minimum radial thickness, for example, between 5 and 20 mm. Figure 5 ).

[0058] Advantageously, the pin bushing 53 may have an enlarged intermediate portion 530 and two connecting bushing ends 532, the average or maximum diameter of which is smaller than that of the intermediate portion.

[0059] The enlarged middle section 530 is intended to engage the drive sprocket 32 ​​of the drive annular track 5, enabling the tracked vehicle to move, and to withstand the wear caused by the drive sprocket during travel.

[0060] Preferably, each connecting bushing end 532 is separated from the middle portion by a shoulder 534.

[0061] The ratio LTN / LB between the length LTN of the enlarged intermediate portion 530 and the total length LB of the bushing 53 is preferably between 0.2 and 0.8, more preferably between 0.3 and 0.6 or 0.4 and 0.45.

[0062] The ratio DB1 / LB between the outer diameter DB1 of the enlarged intermediate portion 530 and the total length LB of the bushing 53 is preferably between 0.2 and 0.8, more preferably between 0.3 and 0.6, 0.4 and 0.5 or 0.45 and 0.5.

[0063] Chassis frame assembly 3 may include one or more of the following elements: - Frame 30; - A wheel, such as one or more sprockets 32 and one or more idler wheels 34; at least one sprocket is preferably a drive wheel 32 or an idler wheel 34, such as Figure 1 In idler wheel 34; - Pulleys and roller assemblies 38 and 40, the roller assembly abutting against the traveling track 5, the traveling track 5 rolling and / or traveling above (e.g., roller assembly 40) or below (e.g., roller assembly 38); - A motor or other actuator, gearbox or articulation that drives the walking track 5, and a power supply line, such as an electric wire or hydraulic power line, that provides power to the motor or other actuator.

[0064] The frame 30 may include, for example, welded metal plates, shells and / or beams, each of which has a more or less complex shape.

[0065] Preferably, the chassis assembly 1 includes one or more support roller assemblies 38, 40 configured to roll against and / or over or under the travel track 5.

[0066] exist Figure 1 In one embodiment, the support roller assembly 38 rolls above the track 5, while the support roller assembly 40 rolls below the track 5.

[0067] Preferably, the roller assemblies 38, 40 are disposed between the sprocket 32 ​​and one or more idler wheels 34 - the latter also referred to as idler wheels 34.

[0068] Preferably, the roller bodies 39 and 41 of the roller assemblies 38 and 40 have a smaller outer diameter than the sprocket 32 ​​and one or more idler wheels 34.

[0069] Preferably, the sprockets 32 and 34 change the direction of the walking track 5 significantly more than the direction of change of each roller assembly 38 and 40.

[0070] Chassis assembly 1 also includes a first friction surface 7 and a second friction surface 9 configured to slide relative to each other. Figure 4 and Figure 6 ).

[0071] The first friction surface 7 and the second friction surface 9 are formed by the chassis frame assembly 3 and / or the track 5.

[0072] For example, the first friction surface 7 and the second friction surface 9 can both be formed by the chassis frame assembly 3, both can be formed by the track 5, or one of them - the first friction surface 7 or the second friction surface 9 - is formed by the chassis frame assembly 3 and the other of them - the second friction surface 9 or the first friction surface 7 - is formed by the track 5.

[0073] According to one aspect of the invention, the chassis includes an improved component 52, which may be contained in the chassis frame assembly 3 or the track 5 and at least forms a first friction surface 7.

[0074] The first friction surface 7 is made of a hard coating 5301 obtained by an ultra-high speed laser cladding (EHLA) process.

[0075] In this specification, the term "ultra-high-speed laser cladding (EHLA)" refers to the coating process defined in claim 1 of German patent application DE102011100456A1, namely, a laser deposition welding process, wherein a molten pool is created on the surface by guiding a laser beam onto a molten pool to melt at least one filler material (such as a metallic material), wherein: - The powder of the filler material is melted by a laser beam; - The filler material is melted by the laser beam at a certain distance from the molten pool and introduced into the molten pool in a completely molten form.

[0076] The EHLA process according to this specification can be carried out based on the teachings and different embodiments described in the aforementioned patent application DE102011100456A1.

[0077] For example, according to a particular embodiment of the invention, the laser beam can be focused at a focal point spaced apart from the molten pool in which the filler material melts.

[0078] According to a particular embodiment of the invention, the molten pool and the focal spot move parallel to each other and relative to the surface to be coated at a speed preferably equal to or greater than 20 m / min, more preferably equal to or greater than 50 m / min, more preferably greater than or equal to 100 m / min, and even more preferably greater than or equal to 130 m / min.

[0079] According to a specific embodiment of the present invention, the distance between the molten part of the filler material and the molten pool can be equal to or greater than 0.2 mm, preferably equal to or greater than 1 mm, more preferably less than or equal to 4 mm, and even more preferably equal to or greater than 5 mm and / or equal to or less than 7 mm or 6 mm.

[0080] According to a particular embodiment of the invention, the density of the powder is set such that the laser power of the laser beam reaching the molten pool is preferably less than 80% of the laser power before the laser beam contacts the powder, more preferably less than 60%, 50%, or 30% of the laser power before the laser beam contacts the powder.

[0081] According to a specific embodiment of the present invention, EHLA can be implemented using the features of claim 1 of German patent DE102011100456B4.

[0082] In known laser cladding processes, powdered filler material is fed into a molten pool generated by a laser on the surface of the part to be coated (i.e., the so-called substrate surface); this specifically means that some processing, grinding or heat treatment is required after conventional laser cladding to eliminate excessive deformation of the coated part.

[0083] In contrast, in the EHLA process, the filler powder is fed into the molten pool and the laser beam above the substrate, saving energy and powder, reducing the heated portion of the substrate (i.e., the surface of the part to be coated), and achieving much higher processing speeds.

[0084] Because the EHLA coating process heats a much smaller portion of the part to be coated, EHLA does not substantially change the size, shape, and hardness of the substrate to be coated, and can be performed at or near the end of the manufacturing process of bushings or other improved parts.

[0085] More specifically, EHLA can advantageously be performed after the heat treatment and machining of the bushing, and more generally, it can be performed at or near the end of the manufacturing process of bushing 53 or another improved component.

[0086] In this way, if certain manufacturing steps are performed by external suppliers, the semi-finished parts need to be handled less often, such as when being packaged and unpacked upon delivery to or by external suppliers; in addition, the main manufacturer's production line needs to change tooling less often, or even not at all.

[0087] Preferably, sprockets 32 and 34 form corresponding toothed rings ( Figure 6 Preferably, during travel, the side wings of the toothed engagement pin bushing 53, for example, the generally central portion 530 of the side wings.

[0088] The first friction surface 7 may be, for example, the middle portion 530 of the side wing of the pin bushing 53, or more generally, all or part of the side wing of the pin bushing 53.

[0089] The second friction surface 9 may include one or more of the following elements: the side wings of the teeth of the sprockets 32, 34; the entire or partial surface of the recess of the side wing 530 of the bushing 53, which exists between two adjacent teeth of the sprockets 32, 34 and periodically receives the side wing 530 of the bushing 53 during travel. Figure 5 and Figure 6 ).

[0090] Advantageously, the hard coating has one or more of the following elements by weight: - The carbon content is between 0.5-5.0 wt%; - Chromium content is between 5.0-30 wt%; - The nickel content is between 2.0-15 wt%; - The silicon content is between 0.5-10 wt%; - The boron content is between 1.0-20 wt%; - The iron content balances the content of one or more of the aforementioned elements to 100%.

[0091] More advantageously, the hard coating has the following weight content: - The carbon content is between 0.5-5.0 wt%; - Chromium content is between 5.0-30 wt%; - The nickel content is between 2.0-15 wt%; - The silicon content is between 0.5-10 wt%; - The boron content is between 1.0-20 wt%; - The iron content balances the content of the aforementioned elements to 100%.

[0092] More advantageously, the carbon content is between 1.0 and 3.5 wt%, more preferably between 2.0 and 2.5 wt%.

[0093] More advantageously, the chromium content is between 10-18 wt%, more preferably between 13-14 wt%.

[0094] More advantageously, the nickel content is between 3.5-10 wt%, more preferably between 5.5-6.5 wt%.

[0095] More advantageously, the silicon content is between 1.0 and 5.0 wt%, more preferably between 2.0 and 2.5 wt%.

[0096] More advantageously, the boron content is between 2.5 and 8.0 wt%, more preferably between 3.5 and 4.0 wt%.

[0097] Preferably, the hard coating comprises one or more of the following materials: tungsten carbide, molybdenum boride, vanadium carbide, martensitic steel, nickel or nickel alloy, cobalt or cobalt alloy, and chromium carbide.

[0098] Preferably, the hard coating has one or more of the following substances in its content: - The tungsten carbide content is between 0-50 wt%, or between 10-20 wt%, or between 20-30 wt%, or between 30-40 wt%, or between 40-50 wt%; - The content of cobalt, cobalt alloy, nickel, or nickel alloy is between 0-30 wt%, or between 5-20 wt%, or between 7-15 wt%, or between 10-30 wt%, or between 10-14 wt%, for example, equal to 12 wt%; - The content of martensitic steel is between 40-99 wt%, or between 50-95 wt%, or between 50-90 wt%; - The content of molybdenum boride or chromium carbide is between 0-40 wt%, or between 10-40 wt%, or between 5-20 wt%, or between 5-15 wt%; - The vanadium carbide content is between 0-40 wt% or between 5-30 wt%; - The titanium content is between 1.0-8.0 wt%, more preferably between 2.0-7.0 wt% or between 4.0-5.0 wt%.

[0099] Preferably, the hard coating comprises a matrix and one or more enriching substances.

[0100] Preferably, the enriched material forms a hard coating at a concentration of 0-30 wt%, 5-20 wt%, or 5-15 wt%.

[0101] Preferably, the remaining content of the matrix forming the hard coating 5301 by weight.

[0102] Preferably, the matrix comprises cobalt or a cobalt alloy and / or nickel and / or a nickel alloy.

[0103] Preferably, the enriching material includes one or more of the following: martensitic steel, cobalt (e.g., essentially 99% pure cobalt, 90% pure cobalt, or other cobalt alloys with cobalt as the main component, such as at least 50% cobalt, at least 60% cobalt, at least 70% cobalt, or at least 80% cobalt), chromium carbide, molybdenum carbide, and vanadium carbide.

[0104] Preferably, at least one enriching substance includes one or more of the following substances: tungsten carbide, molybdenum boride, and vanadium carbide.

[0105] Preferably, the hardness of the hard coating is between 50-100 HRC, or between 55-90 HRC, or between 60-80 HRC.

[0106] Preferably, the average thickness of the hard coating is between 0.2-4 mm, or between 0.5-0.4 mm, or between 0.5-3.5 mm, or between 0.5-2.5 mm, or between 0.5-2 mm, or between 0.2-1 mm.

[0107] Due to the aforementioned composition and / or dimensions, the hard coating exhibits high hardness and abrasion resistance, for example, reducing wear on the substrate by approximately 70%. This percentage was obtained from testing improved components of the chassis assembly under design conditions, particularly corresponding to the number of hours or cycles of the component under design conditions.

[0108] Advantageously, the surface roughness Rz of the first friction surface 7, which is made by the hard coating produced by EHLA, is less than or equal to 300 μm and / or the surface roughness Ra is less than or equal to 50 μm.

[0109] More preferably, the surface roughness Rz is less than or equal to 285 μm, or less than 75 μm, or less than 25 μm, or less than 23 μm, or less than 20 μm, or less than 10 μm.

[0110] More preferably, the surface roughness Ra is less than or equal to 48 or 49 μm, or less than 15 μm, or less than 12 μm, or less than 10 μm, or less than 6 μm, or less than 5 μm.

[0111] The surface roughness Rz can be, for example, between 8-300 μm, or between 10-300 μm, or between 10-20 μm, or between 20-25 μm, or between 25-75 μm, or between 75-285 μm, or between 285-300 μm.

[0112] The surface roughness Ra can be, for example, between 5-50 μm, or between 5-6 μm, or between 6-10 μm, or between 10-12 μm, or between 12-15 μm, or between 15-48 μm, or between 48-50 μm.

[0113] The aforementioned surface roughness value, which can be obtained through a relatively fast and low-cost EHLA process, further improves the wear resistance of the first friction surface 7 or other EHLA coated surfaces and further reduces the wear of the substrate.

[0114] The above measures allow for the acquisition of pin bushing 53, for example, by the following methods: - Semi-finished bushings are made by extruding metal strips; - The entire semi-finished bushing is induction hardened, for example, by cooling the bushing from the outer diameter, and inducing a martensitic phase transformation over the entire thickness of the bushing, preferably at least on the outer and inner surfaces of the bushing. - The bushing is induction hardened and cooled from the inner diameter, and the pre-hardened portion is tempered; - Then, the bushing undergoes stress relief treatment (e.g., by stress relief annealing), can then be machined, and the outer wing of the bushing can be coated by the EHLA process described above.

[0115] Preferably, the improved component includes a base 5300 coated with a hard coating 5301, the base comprising a substrate selected from the group consisting of materials that may be made of or primarily of such substrates. Figure 5A ): - Steel or other metals that have not been pre-carburized or surface-hardened, for example, because they have never been carburized after the production of a blank or another semi-finished bushing; - Steel with a carbon content of less than or equal to 0.5 wt%, or less than or equal to 0.45 wt%, or less than or equal to 0.30 wt%.

[0116] The base 5300 comprises steel with a carbon content preferably equal to or greater than 0.2 wt%, more preferably equal to or greater than 0.25 wt% or 0.3 wt%, or is made of said steel.

[0117] Preferably, the carbon content of the steel formed or otherwise included in the base 5300 is between 0.1-0.5 wt%, more preferably between 0.4-0.45 wt%.

[0118] For example, the base 5300 may be or include the blank or semi-finished bushing, or a part of the blank or semi-finished bushing.

[0119] The base 5300 may form, for example, the main part of the finished bushing 53, and may form at least half the weight of the finished bushing, or at least 0.7 times, at least 0.8 times, at least 0.9 times, or at least 0.75 times the weight of the finished bushing.

[0120] When the improved component is pin bushing 53, its base is preferably a generally tubular blank or another generally tubular body.

[0121] Avoiding carburizing or surface hardening steps can reduce the time and cost of manufacturing bushing 53 or another improved chassis component.

[0122] More generally, another aspect of the invention relates to a method for producing a bushing 53 or another improved component for a chassis assembly of a tracked vehicle, comprising the following steps: - Provide a semi-finished base (e.g., by extrusion) that is made of or contains steel that has not been pre-carburized or surface-hardened; - At least a portion of the substrate of the semi-finished product is coated by the EHLA process to create a hard coating that forms the first friction surface 7; The method for producing the improved component does not include the steps of carburizing or surface hardening the semi-finished or finished substrate.

[0123] Avoiding carburizing or surface hardening of the entire pin bushing 53 or other improved components 53 simplifies the manufacturing process and reduces manufacturing costs; this advantage is particularly significant because carburizing and surface hardening are thermochemical processes, which are special manufacturing processes that require special and expensive systems and facilities.

[0124] EHLA treatment allows hardening only the worn areas of bushing 53 or other improved components, avoiding the hardening of other areas that are not affected by wear or whose wear is negligible.

[0125] In summary, avoiding carburization or surface hardening significantly reduces manufacturing costs and improves—or at least does not worsen—the performance of components.

[0126] More generally, the EHLA coating process allows for the creation of a thick, hard coating 5301, which significantly reduces wear on friction surfaces 7 and / or 9.

[0127] Furthermore, EHLA coating is more efficient than other coating processes because approximately 90% of the coating powder injected into the laser beam reaches the molten pool created by the beam on the surface to be coated, rather than dissipating into the surrounding environment. Also, EHLA can be performed at very high speeds, allowing for processes such as approximately 1000 cm⁻¹. 2 The coating is applied at a rate of / min (square centimeters per minute).

[0128] The previously described embodiments can be modified in various ways without departing from the scope of protection of this invention.

[0129] For example, the improved component according to the invention may not only be the pin bushing 53, but may also be, for example, a roller assembly 38, 40, track anti-slip tooth 510, or part of the track chain.

[0130] Any references to “an embodiment,” “an embodiment,” and “an exemplary embodiment” in this specification mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one implementation of the invention.

[0131] These phrases appearing in various places in the specification do not necessarily refer to the same embodiment.

[0132] Furthermore, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is believed that implementing such features, structures, or characteristics in conjunction with other embodiments is within the capabilities of those skilled in the art.

[0133] All structural details can be replaced with technically equivalent elements.

[0134] Phrases such as “A includes B, C, and D” or “A is made of B, C, and D” should be understood as including and disclosing the specific situation that “A is composed of B, C, and D”.

[0135] Unless otherwise stated, phrases such as "A includes element B" should be understood as "A includes one or more elements B".

[0136] Mentioning "first, second, third... nth element" is only to distinguish the elements from each other, but mentioning the nth does not necessarily mean that there are first, second, third... n-1th elements.

[0137] Examples and lists of possible alternatives should be understood as non-exclusive.

Claims

1. An improved component (53) of a chassis assembly (1) for a tracked vehicle, wherein: - The chassis assembly (1) includes a chassis frame assembly (3) and a track (5) that can be assembled onto the chassis frame assembly so as to be able to move relative to the chassis frame assembly; - The chassis assembly (1) further includes a first friction surface (7, 540) and a second friction surface (9, 560) configured to slide against each other. - The first friction surface (7) and the second friction surface (9) are formed by the chassis frame assembly (3) and / or the track (5); - The improved component (53) is included in the chassis frame assembly (3) or the track (5) and at least forms the first friction surface (7). - The first friction surface (7) is made of a hard coating obtained by an ultra-high speed laser cladding (EHLA) deposition process.

2. The improved component according to claim 1, wherein, The hard coating has one or more of the following elements by weight: - The carbon content is between 0.5-5 wt%; - Chromium content is between 5.0-30 wt%; - The nickel content is between 2.0-15 wt%; - The silicon content is between 0.5-10 wt%; - The boron content is between 1.0-20 wt%; - The titanium content is between 1.0 and 8.0 wt%; - The iron content balances the content of one or more of the aforementioned elements to 100%.

3. The improved component according to claim 2, wherein, The hard coating has one or more of the following elements by weight: - The carbon content is between 2.0-2.5 wt%; - The chromium content is between 13-14 wt%; - The nickel content is between 5.5-6.5 wt%; - The silicon content is between 2.0-2.5 wt%; - The boron content is between 3.5-4.0 wt%; - The titanium content is between 2.0 and 7.0 wt%; - The iron content balances the content of one or more of the aforementioned elements to 100%.

4. The improved component according to one or more of the preceding claims, wherein, The hard coating comprises one or more of the following materials: tungsten carbide, molybdenum boride, vanadium carbide, martensitic steel, nickel or nickel alloy, cobalt or cobalt alloy, and chromium carbide.

5. The improved component according to one or more of the preceding claims, wherein, The hard coating has one or more of the following substances in its content: - The tungsten carbide content is between 0-50 wt%; - The content of cobalt, cobalt alloy, nickel or nickel alloy is between 0-30 wt%; - The content of molybdenum boride or chromium carbide is between 0-40 wt%; - The content of martensitic steel is between 40-99 wt%; - The vanadium carbide content is between 0-40 wt%; - The titanium content is between 4.0 and 5.0 wt%.

6. The improved component according to one or more of the preceding claims, wherein, The hard coating has one or more of the following substances in its content: - The tungsten carbide content is between 5-45 wt%; - The content of cobalt, cobalt alloy, nickel or nickel alloy or martensitic steel is between 10-14 wt%. - The content of molybdenum boride or chromium carbide is between 5-15 wt%; - The content of martensitic steel is between 50-90 wt%; - The vanadium carbide content is between 5-30 wt%.

7. The improved component according to one or more of the preceding claims, wherein, The hardness of the hard coating is between 50 and 100 HRC.

8. The improved component according to claim 7, wherein, The hardness of the hard coating is between 60 and 80 HRC.

9. The improved component according to one or more of the preceding claims, wherein, The average thickness of the hard coating is between 0.1 and 1 mm.

10. The improved component according to one or more of the preceding claims, wherein, At least the first friction surface (7) made from the hard coating obtained by ultra-high speed laser cladding, also known as EHLA, has one or more of the following characteristics: - Surface roughness Rz is less than or equal to 300 micrometers; - Surface roughness Rz is less than or equal to 23 micrometers; - Surface roughness Ra is less than or equal to 50 micrometers; - Surface roughness Ra is less than or equal to 6 micrometers.

11. The improved component (53) according to one or more of the preceding claims, comprising a base coated with the hard coating, the base comprising a substrate selected from the group consisting of: - Steel that has not been pre-carburized or surface-hardened; - Steel with a carbon content of less than or equal to 0.5 wt%, or less than or equal to 0.45 wt%, or less than or equal to 0.30 wt%; - Steel with a carbon content between 0.1-0.5 wt%; - Steel with a carbon content between 0.4 and 0.45 wt%.

12. The improved component according to one or more of the preceding claims, wherein the improved component is a bushing (53).

13. The improved component according to claim 11 or 12, wherein, The base has a generally tubular shape.

14. A chassis assembly (1) comprising an improved component (53) according to one or more of the preceding claims.

15. A continuous track (5) comprising an improved component (53) according to one or more of the preceding claims.

16. The continuous track (5) according to claim 15, wherein: - The continuous track (5) includes multiple track links, multiple articulated pins 52 and multiple pin bushings (53); - Each track link includes a corresponding hinge pin (52) and a corresponding pin bushing (53), which are fixed and hinged to subsequent track links by the corresponding hinge pin (52); - Each hinge pin (52) passes axially through the corresponding pin bushing (53); - Each pin bushing (53) forms a side wing; - The chassis frame assembly (3) includes at least one sprocket (32, 34) configured to engage the hinge pin (52), abut against the side wing of the pin bushing (53) and / or slide against the side wing; - At least a portion of, and possibly all of, the plurality of pin bushings (53) having the features of claim 10.

17. A method for producing an improved component (53) of a chassis assembly (1) of a tracked vehicle according to one or more of claims 1 to 13, comprising the steps of: - Provide a semi-finished base made of or containing pre-carburized or surface-hardened steel; - At least a portion of the substrate of the semi-finished product is coated by an EHLA deposition process to create a hard coating that forms the first friction surface (7); - The method for producing the improved component (53) does not include the step of carburizing or surface hardening the semi-finished base or finished base.

Images