Patent Application
20240344542
The present disclosure relates generally to methods for applying materials to increase friction and/or decrease clamp load loss in bolted joints.
Machines and other types of equipment often have one or more bolted (clamped) joints. While the size, shape, and application of bolted joints may vary, the general application is the same. A bolt is inserted through a space in two or more materials, whereby a nut threaded onto the bolt is used to compress the two or more materials together. The amount of compression varies depending on the materials being compressed, the capability of the bolt and joint to sustain a certain amount of compression, and the amount of compression applied by a user when compressing the two or more materials together.
Over time, as equipment is used that have bolted joints, failures can occur. One reason for failure may be a complete failure of the bolt/nut system, whereby the bolt or nut sheers and separates, causing a complete failure of the compression of the bolted joint. Another reason for failure may be a reduction of the friction between the compressed interface(s) of the two or more materials being compressed. The reduced friction can allow the two or more materials to “slip,” in reference to each other. Repeated slipping back and forth causes bolt self-loosening.
When some interfaces experience reduced friction, parts that were previously secured may experience slippage and can cause damage to or failure of the equipment or machine itself. Various approaches have been attempted to maintain the friction between compressed interfaces. One approach is described in International Application No. WO2010118747 to Brorson (“the '747 application”). The '747 application describes the use of a friction member to reduce the potential of mutual shear movement in the interface between mating surfaces. The friction member of the '747 application is inserted between the mating surfaces prior to compression. However, such a friction member is an additional part that is used to reduce friction loss. This can increase costs associated with the operation and maintenance of the equipment. Further, damage to the friction member can result in the introduction of pieces of the friction member into various parts of the equipment. Additionally, if the friction member is not designed to withstand the operating conditions experienced by the friction member, the friction member may fail, resulting in a potential complete loss of friction between the mated surfaces.
Examples of the present disclosure are directed to overcoming these and other deficiencies of such systems.
In one aspect of the present disclosure, a machine includes a frame, and a first component associated with the frame, the first component having a first surface, and a friction coating deposited at a plurality of regions on the first surface, each region of the plurality of regions being separated from a remainder of the plurality of regions by an interstitial space of the first surface that is without the friction coating, a second component associated with the frame, the second component having a second surface, and a fastener applying compressive force to the first component and the second component, the friction coating deposited at the plurality of regions on the first surface being held in contact with the second surface by the fastener.
In another aspect of the present disclosure, a joint includes a first material having a first surface, a second material having a second surface, wherein the first surface is in compressive contact from a compressive force with the second material at an interface between the first surface of the first material and the second surface of the second material, a bolt inserted through the first material and second material, wherein the compressive force is provided by a nut tightened onto the bolt, a plurality of friction coatings deposited onto the first surface or the second surface, and a plurality of interstitial spaces between one or more of the plurality of friction coatings.
In a still further aspect of the present disclosure, a method of compressing a first component against a second component includes applying a plurality of friction coatings to a first surface of the first component, wherein the first surface comprises a friction coating deposited at a plurality of regions on the first surface, each region of the plurality of regions being separated from a remainder of the plurality of regions by an interstitial space of the first surface that is without the friction coatings, placing the first surface of the first component in contact with a second surface of a second component, wherein the plurality of friction coatings are at an interface between the first surface and the second surface, and applying a compressive force to compress the first surface against the second surface, wherein the compressive force causes deformation of at least a portion of the second surface by the friction coating such that the interstitial space of the first surface contact corresponding portions of the second surface.
In an additional aspect of the present disclose, a joint formed using a first component and a second component is formed by applying a plurality of friction coatings to a first surface of a first material, wherein the first surface further comprises at least one interstitial space between at least a portion of the plurality of friction coatings, wherein the friction coatings are comprised of a tungsten/carbide alloy, a stellite/carbide alloy, an alloy of iron, chromium, boron, manganese, silicone, and nickel, or Ni-20Cr, aluminum oxide (Al2O3) particles, placing the first surface of the first material in contact with a second surface of a second material, wherein the plurality of friction coatings are at an interface between the first surface and the second surface, and applying a compressive force to the first material and the second material.
Wherever possible, the same reference numbers will be used throughout the drawings to refer to same or like parts.
Turning now to the figures,
The machine 100 includes one or more prime movers (e.g., a power source 102) that provide power to the machine 100. For example, the power source 102 can be one or more various types of sources of power that provide energy to the machine 100 to operate the various systems and components of the machine 100. For the power source 102 can be a combustion engine (e.g., a diesel engine) that combusts a fuel to provide mechanical energy to the machine 100. In another example, the power source 102 can be a battery that provides electrical energy to the machine 100. In a still further example, the power source 102 can be an electrically conductive tether attached to a source of electrical power. The presently disclosed subject matter is not limited to any particular type or number of the power source 102. The example embodiment of the machine 100 includes a track-type undercarriage 120.
The machine 100 includes a frame 140 having a first track chain assembly 160 disposed on a first side 110 thereof, and a second track chain assembly (not shown) disposed on a second side (not shown) thereof. The second side is in opposing relationship to the first side 110. Together, the track assemblies are adapted to engage the ground, or other surface, to propel the machine 100 in a backward and/or forward direction.
It should be appreciated that the track chain assemblies of the machine 100 may be similar and, further, may represent mirror images of one another. As such, only the first track chain assembly 160 will be described herein. It should be understood that the description of the first track chain assembly 160 may be applicable to any number of second track chain assemblies, as well. Other embodiments, in accordance with the disclosure, may include more than two track chain assemblies. Thus, the apparatus, systems, and methods, as disclosed herein, apply to any suitable machine, or variations thereof. Additionally, the disclosed components of the machine 100 and the mechanism of formation thereof, as discussed herein, may also apply to other systems, such as non-track type machines and/or other mechanical systems. While the machine 100 is illustrated in the context of a track-type machine, it should be appreciated that the present disclosure is not thereby limited, and that a wide variety of other machines having tracks are also contemplated within the present context. For example, in other embodiments, the track chain assembly 160 can be included in a conveyor system, as a track for transmitting torque between rotating elements, or in any other application known to those skilled in the art.
Returning to
In
Clamp load loss can occur while the first material 202 and the second material 204 are clamped (or otherwise compressed) together caused by the nut 208 threaded onto the bolt 206. To reduce issues relating to the movement of the first material 202 in relation to the second material 204 resulting from the clamp load loss, friction coatings 216A-216N (generically referred to herein as “the friction coatings 216,” and individually as “the friction coating 216A,” “the friction coating 216B,” and the like) are deposited onto an upper surface 215 of the second material 204, in the interface 217 between the upper surface 215 of the second material and the lower surface 219 of the first material 202. The friction coatings are deposited in an interface 221 between the first material 202 and the second material 204. In some examples, the hardness of the friction coatings 216 are at least as great as (equal) or greater than the hardness of at least the first material 202 or the second material 204. The friction coating 216 provides microscopic, elevated surfaces in the interface. When the first material 202 and the second material 204 are clamped (or otherwise compressed) together, the particles forming the friction coatings 216 cause the deformation of the second material 204 and/or the first material 202 at the friction coatings 216. In some examples, the deformation of the second material 204 and/or the first material 202 allow corresponding interstitial spaces 220 to come into contact with each. For example, the interstitial space 220A on the surface of the first material 202 is in contact with the interstitial space 220B on the surface of the second material 204.
The friction coatings 216 are deposited using various application technologies including, but not limited to, a high velocity air fuel (HVAF) process. It should be noted that other deposition processes may be used and are considered to be within the scope of the presently disclosed subject matter, including, but not limited to, High-Velocity Oxygen-Fuel (HVOF), a plasma-arc spray, a twin-wire arc spray, glued particle process, or a cold spray.
The High Velocity Oxygen Fuel (HVOF) process is when fuel and oxygen are fed into a combustion chamber and ignited and combusted continuously. The fuels can be gases (hydrogen, methane, propane, propylene, acetylene, natural gas, etc.) or liquids (kerosene, Ethanol, and the like). The High Velocity Air Fuel (HVAF) process is similar to the HVOF process but feeds air rather than oxygen into the combustion chamber for ignition. Plasma-arc spraying is a process whereby a stream of high temperature plasma and a powder coating are carried via an electric arc to a surface for deposition. Twin-wire arc spraying is a process that uses an electric arc between two consumable electrodes of the surfacing materials as the heat source. A compressed gas atomizes and propels the molten material to the surface for deposition.
Cold Spray is a process whereby a stream of pressurized gas is split into two streams, one of which passes through a powder feeder and collects powdered feedstock material for deposition and the other passes through a heater to expand the gas and increase a sonic velocity thereof. The two gas streams are then recombined and pass through a nozzle before accelerating the powdered feedstock where it deforms on the surface forming a deposition. A glued particle process involves depositing the friction coating onto one or more surfaces using a chemical adhesive to adhere the friction coatings onto the surface. For example, the friction coatings 216 may be applied first to an acetate or paper backed “sticker” in a desired pattern and then applied to one or more of the surfaces. In another example, an adhesive can be applied to the friction coatings 216 and then deposited onto one or more of the surfaces. In a still further example, one or more of the surfaces can have an adhesive applied to at least a part of the surfaces, whereby the friction coatings 216 are deposited onto the adhesive.
As used herein, “high velocity” generally means a deposition process in which material is deposited using propellants that accelerate the deposited materials at spray rates of around 800 m/s to 1400 m/s, though velocities higher and lower than that range can be used and are considered to be within the presently disclosed subject matter. As used herein, an HVAF process is a thermal spray process for deposition of coatings for protection of parts, vessels and structures against abrasion, erosion, and corrosion. The HVAF process runs on a fuel gas such as Propane, Propylene, or Natural gas (supplied from cylinders or gas line at 140 psi), and compressed air (supplied by a 400 CFM air compressor at 125 psi). Other examples of deposition technology include, but are not limited to, twin wire arc, low energy welding, electro spark deposition, or glued particles. Various materials may be used as the friction coating 216. These materials include, but are not limited to, a tungsten/carbide or stellite/carbide alloy, iron base alloys such as PMET 290 (an alloy of iron, chromium, boron, manganese, silicone, and nickel), a nickel chromium alloy, e.g., Ni-20Cr, aluminum oxide (Al2O3) particles, and various combinations of these and other suitable materials.
In some examples, the particles forming the friction coatings can be of various sizes at or from approximately 5 μm up to and including approximately 200 μm. The ranges provided herein are for purposes of providing examples. As used herein, a “particle size” is an average diameter of the particle. Thus, when measuring various diameters of a particle, some specific diameters may be different than other diameters of the particle and some diameters may be less than 5 μm and some diameters may be more than 200 μm. In some examples, various particle sizes of the friction coatings can be achieved using various deposition processes, such as those described above. For example, various ranges of the particle sizes and the deposition processes can be: HVAF with a particle size range of approximately 5 to approximately 45 μm; HVOF with a particle size range of 5-53 μm; Cold Spray with a particle size range of 5-53 μm; Laser Cladding with a particle size range of 45-125 μm; and PTA with a particle size range of 53-200 μm. It should be noted that when using these and other deposition processes, the presently disclosed subject matter is not limited to the ranges provided above
In some examples, the second material 204 further includes interstitial spaces 220A-220N (generically referred to herein as “the interstitial spaces 220,” and individually as “the interstitial space 220A,” “the interstitial space 220B,” and the like). The interstitial spaces 220 are areas on the upper surface 215 of the second material 204 between the friction coatings 216. In these examples, the friction coatings 216 do not completely coat the upper surface 215 of the second material 204. Rather, the friction coatings 216 coat only a portion of the upper surface 215 of the second material 204, with the interstitial spaces 222 between the coated portions of the upper surface 215 of the second material 204, illustrated in more detail in
The friction coatings 216 may be deposited or applied using various patterns and in various shapes. In
In step 804, the two or more materials are clamped using various technologies, whereby the friction coatings 216 are located in the interface between the two clamped materials. Various technologies may be used to clamp the materials together including, but not limited to, bolts, rivets, threaded fasteners and tapped holes, threaded components, and the like.
In step 806, the treated, joint may be installed onto a machine, such as the machine 100 of
Those of ordinary skill in the field will also appreciate that the principles of this disclosure are not limited to the specific examples discussed or illustrated in the figures.
The present disclosure provides friction coatings that are configured to reduce clamp load loss. Machines and other equipment may have joints that are formed by compressing one material, typically a metal, to another material using bolts or other types of securement or compressing technologies. During the use of the joint, the joint may experience expansion from the securement means (e.g., stretching) or compression of the clamped surfaces. These and other factors may reduce the amount of pressure applied to the surfaces of the material, causing a reduction or loss of clamp load. If significant enough, the materials may rotate or move in relation to each other, potentially resulting in a failure of the joint or damage to the equipment. The presently disclosed subject matter describes the use of a friction coating deposited in the interface between the one or more materials being clamped. The friction coating provides microscopic, elevated surfaces in the interface. Although not intending to limit the presently disclosed subject matter to any particular theory of operation, the friction coatings 216, in some examples, the elevated surface of the friction coating provide an additional rotational barrier as the materials move apart in the interface caused by clamp load loss. Specifically, in some examples, as the materials separate due to clamp load loss, the friction coatings provide a degree of rotational friction, reducing the ability of the clamped materials to rotate with respect to each other. In some examples, a source of the increased friction is the hard particles of the friction coating embedding into either or both of the clamped materials at the interface when a bolt (or other tightening technology) is tightened. Once the particles of the friction coating are embedded into the mating surface (interface) and mechanically/metallurgically bonded to the coated surface, a shear load required to slip the joint substantially increases. This increase in shear load is because the slipping of the joint, using the friction coating of the presently disclosed subject matter, requires the plastic deformation of the mating surface at each embedded particle location of the friction coating.
Table 1, below; illustrates an improvement in the maintenance of the coefficient of friction using the friction coatings.
As shown in Table 1, the friction coatings applied in a staggered circle, similar to the friction coatings 216 of
The frictional coatings 216 can be applied in various manners. As described above, the frictional coatings 216, in some examples, are deposited or applied in a manner whereby the friction coatings 216 are separated by interstitial spaces 220. Although not intending to limit the presently disclosed subject matter to any particular theory of operation, the interstitial spaces 220, in some examples, can help to maintain the level of the surface of the clamped materials to work in conjunction with the friction coatings 216, e.g., provide the surface upon which the friction coatings 216 interact with. For example, in a dense deposition of friction coatings with little to no interstitial spacing, the surfaces of the clamped materials in the interface 221 can be compressed or deformed. Because, in some examples, the friction coatings 216 maintain a degree of rotational friction by interacting with the surfaces of the clamped materials in the interface 221, a high degree of compression or deformation of those surfaces can reduce the amount of surface available to the friction coatings 216 to interact with, thus potentially reducing the efficacy of the friction coatings 216 to maintain a degree of rotational friction. In some examples, the use of interstitial spaces 220 maintain a degree of elevation of the clamped surfaces. Thus, as described hereinabove, the friction coatings of the presently disclosed subject matter can increase and maintain the coefficient of friction between clamped surfaces, thereby, in some examples, effectively reducing clamp load loss.
Unless explicitly excluded, the use of the singular to describe a component, structure, or operation does not exclude the use of plural such components, structures, or operations or their equivalents. As used herein, the word “or” refers to any possible permutation of a set of items. For example, the phrase “A, B, or C” refers to at least one of A, B, C, or any combination thereof, such as any of: A: B; C: A and B; A and C: B and C: A, B, and C: or multiple of any item such as A and A: B, B, and C: A, A, B, C, and C: etc.
While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems, and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.
