JP5372336B2 - Track / chain coupling bracket and chassis truck roller with metal bond coating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide undercarriage assembly components of track-type machines having a PTA (plasma arc) welded wear-resistant coating and methods for forming such coated undercarriage assembly components. <P>SOLUTION: Bodies 602 of the undercarriage assembly components, formed of an iron-based alloy, have a material PTA welded on a surface or into an undercut or a channel 630 of the iron-based alloy. A heat treatment of the formed components further hardens the body. The portion of the outer surface of the undercarriage assembly components having the wear-resistant coating corresponds to a wear surface of the component during the operation of the endless track of the track-type vehicle. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  This application is currently referred to U.S. Pat. No. 6,948,784, U.S. Patent Application No. US patent application Ser. No. 10 / 090,617, filed Jul. 1, 2005, which is a continuation-in-part application. 11 / 171,193, which is a continuation-in-part application, the entirety of each of which is incorporated herein by reference.

  The present disclosure generally includes components of a track-type machine, such as a track / chain / bottom roller, a track / chain coupling fitting, a track / pin / bush (bearing cylinder), a track / pin, and a track / pin / bush connection mechanism. It is about. Specifically, chassis assembly components and other truck-type machine components, such as wear-resistant coatings, such as the bottom roller surface, the surface on which the track and chain fittings engage and disengage, The outer surface of the track pin bush that the sprocket engages and disengages, the inner surface of the track pin bush, the hinge pin bush that allows the two mechanical members to move with hinges, and the track pin -For a component with a wear-resistant coating that is metallically bonded to a portion of the component subject to wear, such as at least one of the outer diameter surfaces of the pin at the bush and hinge pin joint.

  In the discussion of the state of the art below, certain structures and methods may be referred to. However, the following references should not be construed as an admission that these structures and methods constitute prior art. Applicants expressly reserve the right to demonstrate that such structures and methods are not eligible as prior art to the present invention.

  The endless track is a chain composed of a connecting bracket, a track pin bush, a track pin, a bottom roller, and a shoe. FIG. 1 shows these chassis assembly components in a typical part of a truck-type machine, ie a truck on a crawler tractor. Each part of the track has a pair of couplings that are securely attached to the track pin bushing at one end and a track pin at the other end. The track pins fit inside the bushing and hold the next pair of coupling fittings. Both track pins and track pin bushings are usually “pressed” into the fittings so that parts do not leave during the service life of the truck. A single track pin, a so-called master pin, is held on each track by a snap ring, which makes it possible to remove and separate the track when, for example, the track is repaired or maintained. A truck shoe with a desired grip or grower determined by the intended use environment (eg clay, slit, loam, gravel, snow, mud, painted surface) is bolted to each part and towed Yes.

  Truck type machine chassis assembly components, for example, track chain bottom roller, track chain coupling bracket, track pin bushing, track pin, track pin bushing mechanism for track type machine endless truck Etc. are exposed to a very harsh operating environment. For example, trucks and chassis of track type machines such as crawler tractors can be debris, dirty water, rocks, etc. during operation. After that, these substances accumulate on the engagement surface of the chassis assembly component and the engagement surface of the driving machine, are packed in the part between them, or directly on the surface of the chassis assembly component. Rub, wear, dent, scratch or tear. If the truck is adjusted too tightly, the friction becomes strong, which causes the wear of the chassis assembly components such as the truck pin and the truck pin bushing. In extreme cases, if the truck is very tightly adjusted, the truck can overheat and melt, which can “reduce” the hardness of the chassis assembly components such as truck pins and truck pins and bushings. That is, heat treatment of the component parts results in a decrease in the hardness of the component parts, and may even cause the track pins and the track pin bushings to fuse. On the other hand, if the track is too loose, it will allow the drive sprocket teeth to jump over the connecting bracket, especially at the back, and the chassis assembly parts such as drive sprocket teeth, track pins, track pin bushings, etc. Causes the components to wear out.

  The chassis assembly components are subject to wear. For example, there are two types of wear on track pins and track pin bushings: external wear and internal wear. External wear occurs on the outer diameter of the track pin bushings in the area where the teeth of the drive sprocket come into contact. This contact area is more than about one third of the surface of the track pin bushing and occupies most of the central length of the track pin bushing. Wear occurs on the outer diameter of the track pin and on the inner diameter of the track pin bush. Further, when the track pin bushing is fitted to the counter bore of the track connecting bracket, internal wear may occur on the outer diameter of the end of the track pin bushing. Thus, current track pins and track pin bushings in endless trucks experience wear and pressure that can adversely affect the service life of the track pin bushings.

  Current track pins and track pin bushings are typically made of a cured material to reduce wear and increase service life. For example, current track pins are quenched by carburizing and quenching the alloy. However, these materials and methods still have a relatively short service life. Therefore, in addition to selecting materials for hardness and wear resistance, current track pins and track pin bushings give a new wear surface to the sprocket by turning or replacing, resulting in extended service life. . For example, see below. Louis R. Hathaway, Ed. “Tires and Tracks, Fundamentals of Service,” Moline, IL: Deere and Company, 1986, pp. 47-67. However, track pins and track pin bushings need to be turned before they wear beyond the limits of wear. Otherwise, service becomes impossible. Thus, frequent inspection and maintenance of track pins and track pin bushings occurs to locate and improve worn components, resulting in associated equipment and personnel downtime.

  In addition, other pin / bush (P / B) connection mechanisms are widespread as hinges between two machine members in various machines such as heavy machinery including tractors, construction, forestry, and mining machines. . While the P / B connection mechanism is used as a hinge, it is also required to function as a bearing with a load during relative movement between two mechanical members connected to the connection mechanism. Such a connection mechanism is exposed to a dusty environment, depending on the location on the machine and on the type of machine. Dust from this environment is often fine sand particles, but it gets into the space between the pin and bushing and promotes wear of the pin and bushing mating surfaces, shortening the life of the connection mechanism. For this reason, it is necessary to replace the connection mechanism even if the lubricating oil is frequently changed every day or every week. The reason why the sand particles promote the wear is that the sand is harder than the hardness of the surface of the pin or bush.

  In conventional track / pin bushings, the mating surfaces, i.e., the outer surface of the pin and the inner diameter surface of the bush, are carburized and the parts are then quenched and tempered to obtain a high surface hardness. These hard surfaces are more resistant to abrasion by fine sand particles (entering the gap between the pin and the bush from the external environment) than when not carburized. This leads to extending the life of the P / B connection mechanism. However, even the surface hardness obtained by this method by carburizing and quenching is only about 60-62 HRC, which is much less than the hardness of the sand particles, so this approach has limited P / B wear. Only provides protection and extended life. Sand particles entering the gap between the pin and the bush are mixed with the lubricating oil (injected into the gap) and the effectiveness of the lubricating oil is gradually reduced. For this reason, depending on the degree of the sealing effect of the connection mechanism and depending on the environment in which the machine is operating, sand is discharged from the connection mechanism, so that grease is forced from the clearance space of the connection mechanism frequently and sometimes every day. Need to go outside. Such frequent purging of the grease helps to extend the life of the connection mechanism to some extent. However, if it is necessary to perform this purging operation frequently, it takes time and is wasteful.

  Other current chassis assembly components are typically made of a cured material to reduce wear and increase service life. For example, current bottom rollers are hardened by quenching. However, these materials and methods still have a relatively short service life. Since sand is much harder than hardened steel, wear problems are exacerbated and bottom roller wear cannot be significantly reduced by simply hardening the contact surface. Therefore, frequent inspection and maintenance of the bottom roller occurs to locate and improve worn components, resulting in associated equipment and personnel downtime. Similar efforts and similar limited results are known for other chassis assembly components.

  Further, for example, a chassis truck / chain coupling fitting that forms a part of the chassis assembly is exposed to severe wear and corrosion. Wear is due to contact with the chassis roller, which is itself cured. The degree of wear is increased by the abrasive action of dry sand, wet sand suspension (slurry) confined between the coupling metal and the contact surface of the roller, or a hard substance such as rock. Since sand is much harder than hardened steel, the wear problem is further exacerbated and the wear of the fittings cannot be significantly reduced by simply hardening the contact surfaces. Therefore, solutions other than heat treatment are required to reduce wear and greatly extend the life of the fittings.

  Also, due to the functional nature of crawlers and other construction and mining machines, the chassis components of these machines need to maintain continuous and intimate contact with wet sand and mud. For this reason, the surface of a connection metal fitting corrodes and a synergistic effect with wear is produced. This corrosion cannot be reduced by hardening the steel. Other surface treatments of the fittings, such as carburizing, nitriding, or other conventional surface treatment methods, are not cost effective against the severe wear and corrosive environments that the fittings encounter during service. More expensive materials, such as high alloy steels and other advanced materials, cannot be used and are not an acceptable solution because such a replacement adds considerable cost.

  There is a need for a solution that can reduce both wear and corrosion and that can be applied to production environments at low cost.

  A change in the current manufacturing process of the component is proposed. Current methods include hot forged medium carbon steel containing various amounts of boron, manganese, chromium, etc., and cut mating surfaces and induction hardened selected surfaces.

  “Hardfacing” or “hard” means that the metal surface is coated with another metal or alloy to improve the appearance, protect against corrosion, and improve wear resistance. often referred to as “surfacing”. For example, Alessi US Pat. Re. 27,851, Revankar US Pat. 5,027,878 and no. No. 5,443,916, Brady et al. 4,682,987 and Hill, US Pat. See 5,456,323.

Hardening is often performed by fusing a powdered hard metal alloy onto the metal surface. When applied to an endless track, metal parts that are subject to wear can be baked to improve wear resistance. However, if the wear resistant coating is applied prior to carburization as is currently the case, the wear resistant coating will oxidize during the subsequent carburization, resulting in a negative impact on the wear resistance of the coating.
US Pat. No. 5,456,323

  Therefore, endless truck chassis assembly components used in truck-type machines such as trucks, pins, and bushes are subject to wear and tear in order to extend service life and reduce long-term maintenance costs associated with endless trucks. Such a surface is desirable. Furthermore, while coating with an abrasion resistant alloy produces a time consuming surface, the desired wear resistance of the uncoated part of the component can also be obtained by other suitable means, ie quenching. A method is desired.

  Also, due to the functional nature of large construction, mining and forestry machines, the chassis assembly components and hinge connection mechanism components of these machines are all in close contact with wet sand and mud during machine operation. Need to keep in touch. For this reason, the surface of a component such as a bottom roller is corroded, and a synergistic effect with wear occurs. This corrosion cannot be reduced by hardening the steel. Other bottom roller surface treatments, such as carburizing, nitriding, or other conventional surface treatment methods, are cost effective for the highly wear and corrosive environments that the bottom roller faces during service. Is not good or appropriate. More expensive materials, such as high alloy steels and other advanced materials, cannot be used because such replacement would add significant cost and there is no appreciable increase in performance. I can not say.

There is a need for a solution that can reduce both wear and corrosion and that can be applied to production environments at low cost.
U.S. Pat. No. 6,414,258 discloses a method of applying hard material beads to the sprocket teeth and bushes of the undercarriage of a tracked vehicle. In this method, beads are applied sequentially by a weld overlay (which is clearly a slow process) to form a sinusoidal surface. This is disadvantageous for mating parts such as chain connection fittings. Since the deposits are essentially balls, it takes a considerable amount of time to produce a smooth surface by initial wear. Before this smooth wear surface is created, the deposited contact surface can damage the surface of the connecting fitting to be joined.

  The object of the present invention is to avoid or at least solve the problems of the prior art.

  A further object of the invention is to provide a wear resistant coating on at least the bottom roller of the chassis truck chain.

In one aspect of the invention, a track pin bushing is provided that cooperates with a track pin in an endless track, the track pin bushing comprising:
A tubular body made of an iron-based alloy and having a first end and a second end, the outer surface having at least a portion thereof surface hardened and an inner surface having an inner diameter The inner diameter defines the circumference of an axial hole extending from the first end to the second end, and at least a portion of the surface hardened portion exposes a non-carburized layer of the iron-based alloy. A tubular body that has been removed to a depth sufficient for
A wear-resistant coating that is metal bonded to the non-carburized layer, wherein the wear-resistant coating comprises iron, or cobalt, nickel, or a fused hard metal alloy comprising at least 60% of their alloys. A protective coating;
including.

In a second embodiment, a track pin bushing is provided that cooperates with a track pin in an endless truck,
A first end and a second end;
An inner surface having an inner diameter, the inner surface defining a circumference of an axial hole extending from the first end to the second end;
An outer surface having a first outer diameter at a first end portion and a second end portion and a second outer diameter at an intermediate portion therebetween, the second outer diameter being a first outer diameter An outer surface larger than the diameter,
An annular groove located in at least a portion of the intermediate portion, the annular groove extending over half the axial length of the intermediate portion;
A wear-resistant coating disposed in the annular groove and metal-bonded to the track pin bushing, comprising a fused hard metal alloy comprising at least 60% iron, cobalt, nickel, or alloys thereof. A wearable coating;
including.

In a further aspect of the present invention, there is provided a method for hardening a metal surface of a carburized metal portion with a wear resistant coating, the method comprising:
Removing the carburized metal from at least a portion of the metal surface to a depth sufficient to expose a non-carburized layer of metal, the portion defining an area to be coated;
Contains finely divided powder fusible hard metal alloy containing at least 60% iron, cobalt, nickel, or alloys thereof, polyvinyl alcohol, suspending agent, and peptizer. Coating the area with a suspension;
Forming a metal bond between the area and the coated suspension to form an abrasion resistant coating;
including.

In a second embodiment, there is provided a method for hardening a metal surface of a track pin bushing with a wear-resistant coating, the track pin bushing having an outer surface having an outer diameter and an inner surface having an inner diameter. , Including a first end and a second end, the inner diameter defines a circumference of an axial hole extending from the first end to the second end, the axial hole being an endless track In collaboration with track pins,
Carburizing at least a portion of the track pin bushing to create a surface with carburization depth;
Providing at least a portion of the carburized surface of the track pin bushing within the area to be coated by removing the carburized metal to a depth sufficient to expose the non-carburized layer;
A finely divided powdered fusible hard metal alloy comprising at least 60% of an exposed non-carburized layer of the track pin bushing of iron, cobalt, nickel, or an alloy thereof; Coating with a suspension comprising polyvinyl alcohol, a suspending agent, and a peptizer;
Forming an abrasion resistant coating by metal bonding the exposed non-carburized layer and the suspension;
Quenching the surface of an unprepared carburized truck / pin / bush by quenching; and
including.

In a further embodiment, there is provided a method for hardfacing a metal surface of a track pin bushing with a wear resistant coating, the method comprising:
A first end and a second end, and an inner surface having an inner diameter, the inner surface defining the circumference of an axial hole extending from the first end to the second end; An outer surface having a first outer diameter at the first end portion and a second end portion and a second outer diameter at an intermediate portion therebetween, the second outer diameter being the first outer diameter Forming a track pin bushing having an outer surface larger than the outer diameter;
Carburizing the track pin bushing to create a carburized outer surface, inner surface, first and second end portions, each having a carburized depth;
Removing carburized steel from at least a portion of the intermediate portion and reducing the second diameter by at least the carburization depth;
Contains finely divided powder fusible hard metal alloy containing at least 60% iron, cobalt, nickel, or alloys thereof, polyvinyl alcohol, suspending agent, and peptizer. Coating the intermediate portion within a reduced diameter range with a suspension;
The film thickness of the suspension is adjusted so that it has a concentric outer surface with the axial hole, and the film thickness on the concentric outer surface is 1.67-2. Adjusting to 0 times,
Forming a wear resistant coating by metal bonding the portion of the intermediate portion and the suspension;
Surface quenching at least the inner diameter and the first and second ends;
including.

In a further aspect of the invention, a track pin bushing is provided in combination with a track pin for connecting adjacent track couplings in an endless track of a crawler track, the track pin bushing being axial The track pin is in a position where the track pin passes through it,
A tubular body, surface hardened and formed of an iron-based alloy, having a first end and a second end, an outer surface, and an inner surface having an inner diameter, the inner diameter from the first end A tubular body defining a circumference of an axial hole extending to the second end, a portion of the outer surface being removed to a depth sufficient to expose a non-carburized layer of iron-based alloy;
A wear-resistant coating metallized to said portion, the wear-resistant coating comprising at least 60% iron, or cobalt, or nickel, or a fused hard metal alloy comprising an alloy thereof. Coating,
including.

In another aspect of the present invention, a pin-bush connection mechanism for an endless track of a track type machine is provided, the pin-bush connection mechanism comprising:
A bushing comprising an outer surface having an outer diameter and an inner surface having an inner diameter;
Including track pins including an outer surface;
A portion of the outer surface of the track pin substantially coincides with a portion of the inner surface of the bush to form a friction surface, which has a metal bonded wear resistant coating and is resistant to wear. The abradable coating comprises a fused hard metal alloy comprising at least 60% by weight of iron, or cobalt, or nickel, or an alloy thereof.

In yet another aspect of the invention, a method of making a pin-bush connection mechanism is provided, the method comprising:
Forming a bushing comprising an outer surface having an outer diameter and an inner surface having an inner diameter;
Forming a track pin including an outer surface that substantially coincides with a portion of the inner surface of the bush and forms a friction surface;
Removing a portion of the friction surface from the inner surface of the bush to expose the area of the bush to be coated and removing a portion of the friction surface from the outer surface of the track pin to expose the area of the track pin to be coated When,
A finely divided powder fusible hard metal alloy containing at least 60% by weight of iron, cobalt, nickel, or an alloy thereof, polyvinyl alcohol, a suspending agent, a peptizer; Coating the exposed area of both the bush and the track pin with a suspension comprising:
Forming a metal bond between the exposed area and the coating suspension to form an abrasion resistant coating;
including.

In a further aspect of the invention, a chassis truck chain bottom roller is provided, wherein the chassis truck chain bottom roller is
At least one cylindrical portion;
And at least one flange having a diameter larger than the at least one cylindrical portion,
At least a portion of the at least one cylindrical portion and the at least one flange portion are subjected to wear;
The part exposed to wear has a metal bonded wear resistant coating;
The wear resistant coating comprises a fused hard metal alloy comprising at least 60% by weight of iron, cobalt, nickel, or alloys thereof.

In a further aspect of the invention, a method of making a chassis truck chain bottom roller is provided, the method comprising:
Forming a cylindrical body having at least one cylindrical portion and at least one flange portion;
Removing the outer surface of the portion of the cylindrical portion and flange portion that is subject to wear to expose the area of the roller body to be coated;
A finely divided powder fusible hard metal alloy containing at least 60% by weight of iron, cobalt, nickel, or an alloy thereof, polyvinyl alcohol, a suspending agent, a peptizer; Coating the exposed area with a suspension comprising:
Forming a metal bond between the exposed area and the coating suspension to form an abrasion resistant coating;
including.

In another aspect of the present invention, there is provided a track and chain coupling bracket for an endless truck of a track type machine,
A body formed of hardened steel;
A mounting surface on the first end of the body and including at least one opening for an accessory device; and a contact surface on the second end of the body;
The contact surface is on the opposite side of the mounting surface,
The contact surface includes a substantially planar region extending long along the second end to form a wear surface;
The wear surface has a metal bonded wear resistant coating, the wear resistant coating comprising a fused hard metal alloy comprising at least 60% by weight of iron, or cobalt, or nickel, or an alloy thereof. Contains.

In yet another aspect of the present invention, a method of making a track and chain fitting is provided, the method comprising:
The track and chain coupling bracket includes a body, a mounting surface on the first end of the body, and a contact surface on the second end of the body, the mounting surface including at least one opening for the accessory device, The surface includes a substantially planar region that extends long along the second end to form a wear surface, and forms the track and chain fitting such that the contact surface is opposite the mounting surface. Steps,
Removing a portion of the wear surface to expose a range of track and chain fittings to be coated;
A finely divided powder fusible hard metal alloy containing at least 60% by weight of iron, cobalt, nickel, or an alloy thereof, polyvinyl alcohol, a suspending agent, a peptizer; Covering the exposed area of the track and chain coupling bracket with a suspension containing
Forming a metal bond between the exposed area and the coating suspension to form an abrasion resistant coating;
including.

In yet another aspect, there is provided a track and chain coupling fitting, such as for an endless truck of a truck-type machine,
A body forged from medium carbon steel, wherein the medium carbon steel includes boron, manganese, chromium, and balanced iron;
A mounting surface on a first end of the body, the mounting surface having at least one opening for an accessory device;
A contact surface on the second end of the body;
It has.

  The contact surface is on the opposite side of the mounting surface and the contact surface is operatively in contact with the roller surface of the chassis truck, chain, bottom roller and extends long along the second end to form a wear surface Including a substantially planar region. An undercut extends from the wear surface into the forged body, the plasma arc (PTA) weld coating substantially fills the undercut, and the outer surface of the weld coating is the wear surface of the track and chain fitting. It matches.

In a further aspect, a chassis truck chain bottom roller is provided, wherein the chassis truck chain bottom roller is
At least one cylindrical portion;
And at least one flange portion having a diameter larger than that of the at least one cylindrical portion,
At least one cylindrical portion and at least a portion of the at least one flange portion are subject to wear, an undercut extends from the surface of the portion subject to wear to the interior of the portion, and plasma arc (PTA) welding The coating substantially fills the undercut so that the outer surface of the weld coating coincides with the surface of the portion exposed to wear.

In yet another aspect, a method of manufacturing a chassis component is provided, the method comprising:
Forging the body of the chassis component using medium carbon steel;
Removing the portion of the wear surface of the chassis component to form an undercut extending from the wear surface into the forged body for the purpose of exposing a range of chassis components to be coated;
Applying PTA weld coating to the undercut;
A step of heat-treating a body provided with a PTA weld coating in a first heat treatment procedure, wherein the first heat treatment procedure includes quenching and tempering;
A step of heat-treating the main body in a second heat treatment procedure, wherein the second heat treatment procedure includes a step including induction hardening.

  In an exemplary embodiment, selected chassis assembly components are metallized wear resistant coatings applied by plasma arc welding. Plasma arc (PTA) welding is a high energy inert gas welding process. In general, argon (Ar) is used to supply the arc plasma, transport the powder, and shield the melted material. PTA produces very high quality deposits, thereby protecting the base material with minimal thinning and deformation of the base material. PTA welding can deposit alloy coatings on mechanical parts that are subject to severe wear in a precisely controlled manner, thereby greatly extending service life. PTA welding features a high rate of material deposition of up to about 20 pounds per hour and a smooth bead with minimal or no ripple that causes surface non-uniformity, for example, less than about 0.020 inches. Welding surface.

  When applied to the surface of the chassis, it is desirable that the PTA weld surface be as smooth as possible. PTA welding is preferably homogeneous if possible. During the PTA welding process, the ionized plasma gas stream dissolves the working surface and the flow of powdered alloy material that is fed into the arc. The PTA welding process can reduce the porosity in the as-deposited weld metal. For example, using a high speed plasma at an appropriate rate, a very high density and approximately 1% porous weld coating can generally be achieved by a PTA welding process.

  The PTA welding process uses a non-consumable tungsten electrode. It also uses a nozzle configured to compress the arc and another nozzle to provide shielding gas and consumable powder feed. An arc is created between the electrode and the work piece. The PTA welding process provides the advantage of melting the feed powder at the current location, rather than based on moving the molten metal beyond the welding arc. The PTA welding process can control heat input at a high level. This control is feasible because the compressed arc is very stable and dense. In the PTA welding process, the thinning of the base material can usually be less than 5%, so that the wear resistance of the coating throughout the weld is more consistent. In contrast, other forms of weld deposits can be up to 50% thinner, and the wear resistance of the coating through the weld deposit may be uneven. Materials that are welded with PTA include wear resistant coating materials. These materials include at least 60% by weight of metal alloys including iron, cobalt, nickel, or alloys thereof. The coating material may also include a high carbon content metal matrix composite wear resistant alloy such as tungsten carbide. A typical suitable powdery material that can be used to form an abrasion resistant coating is described in US Pat. No. 6,948,784.

  PTA weld surfaces can be applied to components of crawler track machines to increase wear resistance. In such cases, the PTA weld surface can be used in place of other types of wear surfaces, such as a wear surface with a suspension coating. In this regard, the PTA weld surfaces disclosed herein are disclosed in US Pat. No. 5,879,743, US Pat. No. 6,948,784 and U.S. patent application Ser. 11 / 171,193 can be used in connection with or as an alternative to the wear surface with suspension coating, the entire disclosure of each of these documents is incorporated herein by reference.

  Both the wear surface with suspension coating and the wear surface with PTA welding are disclosed herein.

  In an exemplary embodiment, the chassis assembly component having a wear-resistant coating with a metal bond is a truck pin bush. The track pin bushing cooperates with the track pin in a track type machine, for example, an endless track of a crawler tractor. In the exemplary configuration shown in FIG. 2, the track pin bushing 200 has a cylindrical body formed of an iron-based alloy, at least a portion of which is surface hardened, i.e., the outer side. The surface, inner surface, end face, parts or combinations thereof are carburized and quenched. The track pin bushing 200 has an outer surface 202 having an outer diameter and an inner surface 204 having an inner diameter. The inner diameter defines the circumference of an axial hole 206 that extends from the first end 208 to the second end 210 of the track pin bushing 200. An abrasion resistant coating 212 is disposed over the portion 214 of the track pin bushing 200 and is metal bonded. This is exposed by removing at least a portion of the surface hardened portion to a depth sufficient to expose the non-carburized layer of the iron base alloy.

  In a preferred embodiment, the hardened track pin bushing has an outer surface with an outer diameter that is uniform, i.e. unchanged. At least a portion of the outer surface is surface hardened, i.e. carburized. As shown in FIG. 3A, the track pin bushing 300 has an inner diameter that defines the circumference of an axial hole 304 that extends from a first end 306 to a second end 308 of the track pin bushing 300. It has an inner surface 302. The outer surface 310 has a uniform outer diameter along the axial length L of the track pin bushing 300. A wear resistant coating 312 is metal bonded to the non-carburized layer 314 exposed by removal of a portion 316 of the carburized outer surface 310.

  In another exemplary embodiment, the hardened track pin bushing has an outer surface with a non-uniform, i.e. variable, outer diameter. At least a portion of the outer surface is surface quenched, that is, carburized and quenched. As shown in FIG. 3B, the track pin bushing 318 has an inner surface with an inner diameter that defines the circumference of an axial hole 322 extending from the first end 324 to the second end 326 of the track pin bushing 318. 320. The outer surface 328 has at least one first portion 330 having a first outer diameter and at least one second portion 332 having a second outer diameter. In the illustrated embodiment, the second portion 332 is a central portion between the first portions 330 located at both the first end 324 and the second end 326. Since the second outer diameter is larger than the first outer diameter, the second portion 332 projects from the track pin bush 318 for the entire axial length L ′. A wear-resistant coating 334 is disposed in the non-carburized layer 336 exposed by removal of the carburized material from at least a portion 338 of the second portion 332 and is metal bonded to the non-carburized layer 336.

   On both the outer surface with a uniform outer diameter and the outer surface with a non-uniform outer diameter, the exposed non-carburized layers 314 and 336, and therefore the wear-resistant coating 312 disposed therebetween and metal bonded, 334 extends over a portion of outer surfaces 310 and 328 corresponding to at least the contact surface adapted to engage a drive sprocket in an endless track of a track type machine. In the exemplary embodiment shown, the exposed layers 314 and 336 are formed by removal of the carburized material and look like an annular groove or other pit or cavity formed by removal of the carburized material. . However, the exposed layer can be any shape as long as the wear resistant coating can be fused to the non-carburized surface by metal bonding.

  In one embodiment and application for a crawler tractor labeled John Deere 850C Series H Crawler, the wear resistant coating extends to cover most of the axial length of the track pin bushing. In other embodiments, the wear resistant coating extends over an axial length corresponding to the contact surface for a particular application. A specific application is an application for a specific track-type machine and possibly a short length, one end or multiple ends, one groove or multiple grooves, etc. I understand.

  In a further aspect, as shown in FIG. 3A, the wear resistant coating is integral with the outer surface of the track pin bushing and has the same plane as the outer surface. In other embodiments, the outer surface of the wear resistant coating is not coplanar with the outer surface, but extends beyond the outer surface to provide a higher coating or is recessed from the outer surface. Become a coating. The wear-resistant coating thickness determines the wear life of the track, pin, and bush, the wear-resistant coating thickness can be any desired thickness, and a thicker coating promotes life extension of the wear life . In an exemplary embodiment, the wear resistant coating has a thickness of approximately 1-2 mm.

  In a further exemplary embodiment, the chassis assembly component with a metal bonded wear resistant coating is a separate component of the track pin / bush connection mechanism, eg, the inner diameter of the track pin and the track pin bush. is there. FIG. 4 is a schematic perspective view of the track pin / bush connection mechanism. In FIG. 4, the assembled pin / bush connection mechanism 400 includes a track pin bushing 402 with a track pin 404 inserted in a hole 406 in the track pin bushing 402. FIG. 5 is a schematic perspective view of the disassembled pin / bush connection mechanism 400, and shows a range where the track pin bush 402 and the track pin 404 are hardened. An exemplary pin / bush connection mechanism 400, eg, an endless track pin / bush connection mechanism of a track type machine, includes an outer surface 410 having an outer radius R ′ and a bush 402 including an inner surface 412 having an inner radius r ′. And a track pin 404 that includes an outer surface 414. A portion 420 of the outer surface 414 of the track pin 404 substantially coincides with a portion 422 of the inner surface 412 of the bushing 410 to form a wear surface with a wear-resistant coating due to metal bonding. The wear resistant coating comprises a fused hard metal alloy comprising at least 60% by weight iron, or cobalt, or nickel, or alloys thereof.

  FIG. 6 is a schematic cross-sectional view of a typical track pin bushing 402 with a hard overlay. In FIG. 6, an outer surface 410 having an outer radius R 'and an inner surface 412 having an inner radius r' are visible. Also shown is a portion 422 of the inner surface 412 of the bushing 410 that contributes to the formation of a wear surface. Portion 422 is filled with a wear-resistant coating 428 with a metal bond and is optionally a groove in the body 426 of pin bushing 410 cut to the desired surface location and roughness, eg, the same height as the inner radius r. It is shown as 424. Optionally, portion 422 may be any portion of the length of hole 406, including the entire length. The wear resistant coating 428 by metal bonding also does not perform any pre-cutting, such as pre-cutting to form the groove 424, and optionally directly on the inner surface 412 of the as-formed pin bushing 410. It may be applied. In addition, optionally, the outer surface of the bushing, eg, the outer surface 410 in FIG. 6, can be hardened along the entire area or part of the area using a similar metal-bonded wear-resistant coating. You can also.

  FIG. 7 is a schematic cross-sectional view of a typical hardened track pin 404. Also shown is a portion 420 of the outer surface 414 of the track pin 404 that contributes to the formation of a wear surface. Portion 420 is filled with a metal-bonded wear-resistant coating 434 and optionally a groove in the body 432 of the pin 404 cut to the desired surface location and roughness, eg, the same height as the outer surface 414. It is shown as 430. Optionally, portion 420 may be any portion of the length of pin 404, including the entire length. The wear-resistant coating 434 by metal bonding is also applied directly to the outer surface 414 of the as-formed pin 404 without any pre-cutting such as pre-cutting to form the groove 430. May be.

  In the modified manufacturing process of the proposed pin / bush connection mechanism, the forged pin bushing and the forged track pin are used for the parts of the pin bushing and the track pin that contact the pin / bush connection mechanism, such as the wear surface. Nearby, only a small amount (usually 1-2 mm depending on the required wear coating thickness) is cut off (undercut). Then, when fused, the suspension coating is applied to the cut surface to the desired surface, i.e. the film thickness so that the surface obtained before undercutting matches the surface of the suspension. . The fused suspension coating forms a strong metal bond, which can be applied from heating and cooling to the steel substrate in the same way as during quenching or when subjected to severe impact loads during service. There is no crushing.

  Similar to the discussion and processing of the pin-bush connection mechanism disclosed herein, other types of pin / bush connection mechanisms, such as a hinge-pin-bush, in which the two mechanical members are hinged, are also metallized. Can have an abrasion resistant coating. The discussion and processing related to pin-bush connection mechanisms disclosed herein is generally equally applicable to these other types of pin-bush connection mechanisms, and it should be understood that this disclosure Extended to other types of pin-bush connection mechanisms.

  In another exemplary embodiment, the chassis assembly component having a wear-resistant coating by metal bonding is a chassis truck chain bottom roller. FIG. 8 is a schematic perspective view of a typical chassis truck / chain / bottom / roller, and shows a range where hardened is applied. In FIG. 8, the outer surface 502 is shown. The outer surface 502 has a substantially cylindrical region 504 that is axially and outwardly bounded by a flange portion 506. At least one flange portion 506 is larger in diameter than the substantially cylindrical region 504. Also shown is a mounting surface 508 for installation on a truck of a truck-type machine. The substantially cylindrical region 504 is adapted to contact the contact surface of the track and chain fitting, such as the upper rail surface of the chain fitting found on the track of the track type machine shown in FIG. Yes. During operation, part or all of the substantially cylindrical region 504 and the flange portion 506 are subject to wear, and therefore, part or all of the substantially cylindrical region 504 and the flange portion 506 are against it. Hardened.

  FIG. 9 is a schematic cross-sectional view of a chassis truck chain bottom roller 500 with a hardfacing showing a substantially cylindrical region 504, a flange portion 506, and a mounting surface 508. FIG. The portion 520 and flange portion 506 of the substantially cylindrical region 504 are wear resistant due to metal bonding, including a fused hard metal alloy comprising at least 60% by weight iron, or cobalt, or nickel, or alloys thereof. It has a protective coating 522. Two variations (A and B) of the portion 520 are shown in FIG. Including these, a plurality of variations not shown may be used. Further, while FIG. 9 shows a bottom roller 500 incorporating two different variations (A and B), it should be understood that both uniform and different variations may be used.

  A portion 520 having a metal bonded wear resistant coating 522 is shown as a groove 530 in the body 532 of the substantially cylindrical region 504. In one exemplary embodiment, the groove 530 is filled with a metal-bonded abrasion-resistant coating 522, optionally with a desired surface location and roughness, eg, substantially cylindrical region 504. And is cut to the same height as the outer surface 502. In addition, the wear-resistant coating 522 by metal bonding does not perform any pre-cutting, such as pre-cutting to form an arrangement range, such as a groove 530, and is optionally left as formed. It may be formed directly on the outer surface 502 of the track chain bottom roller.

  Optionally, an exemplary embodiment provides resistance to metal bonding in any portion of the substantially cylindrical region 504, including the entire length of one or more outer surfaces of the substantially cylindrical region 504. An abradable coating 522 may be included. Further optionally, the exemplary embodiment may include a metal bonded wear resistant coating 540 on any portion of the flange portion 506, including the entire length of one or more outer surfaces of the flange portion 508. When a metal-bonded wear-resistant coating 540 is included in any portion of the flange portion 508, the metal-bonded wear-resistant coating 540 is a metal bond associated with a substantially cylindrical region 504 (shown in Variation A). A coating other than the wear-resistant coating 522 may be used. Alternatively, the wear resistant coating with metal bonds on the flange may be continuous with the metal bond wear resistant coating 522 associated with the substantially cylindrical region 504, at least on the outer surface 502. In addition, the wear-resistant coating 540 by metal bonding does not perform any pre-cutting, such as pre-cutting to form an arrangement range, such as a groove 542, and is optionally left as formed. It may be formed directly on the outer surface 502 of the track chain bottom roller 500.

  In the proposed modified bottom roller manufacturing process, the bottom roller is near the wear surface, such as the portion of the bottom roller that contacts the track chain fitting, for example, a substantially cylindrical area or portion of the flange portion. Then, only a small amount (usually 1-2 mm depending on the required thickness of the wear coating) is cut off (undercut). Then, when fused, the suspension coating is applied to the cut surface to the desired surface, i.e. the film thickness so that the surface obtained before undercutting matches the surface of the suspension. . The fused suspension coating forms a strong metal bond, which can be applied from heating and cooling to the steel substrate in the same way as during quenching or when subjected to severe impact loads during service. There is no crushing.

  In another exemplary embodiment, the chassis assembly component having a wear-resistant coating by metal bonding is a truck / chain coupling fitting. FIG. 10 is a schematic perspective view of the first side of a typical track / chain coupling fitting, and shows a range where hardened is applied. In the exemplary embodiment, the track and chain fitting 600 includes a body 602 formed of hardened steel, a mounting surface 604 on the first end 606 of the body 602, and a contact on the second end 610 of the body 602. Including a surface 608. The mounting surface 604 includes at least one opening for the mounting device. For example, as shown in FIG. 1, the accessory device is an accessory device for adding a track / chain connecting bracket to a shoe of a truck of a truck type machine in a fixed or removable manner. Contact surface 608 is opposite the mounting surface and includes a substantially planar region 614 that extends long along second end 610 to form a wear surface.

  At least a portion of the wear surface, eg, a portion 620 of the substantially planar region 614, has a metal bonded wear resistant coating 622, and the metal bonded wear resistant coating 622 is at least by weight. It includes a fused hard metal alloy containing 60% iron, or cobalt, nickel, or an alloy thereof. A portion 620 having a wear-resistant coating 622 with a metal bond has a groove 630 in the body 602 of the track and chain fitting 600. In one exemplary embodiment, the groove 630 is filled with a metal-bonded wear-resistant coating 622 and optionally a desired surface location and roughness, eg, a substantially planar region 614 and Cut to the same height. In addition, the wear-resistant coating 622 by metal bonding does not perform any pre-cutting, such as pre-cutting to form a placement area, such as a groove 630, and optionally remains tracked. -You may give directly to the outer surface of the chain coupling metal 600. FIG.

  In the proposed modified manufacturing process for track and chain fittings, the surface of the forged fitting that contacts the roller surface is cut off by a small amount (usually 1-2 mm, depending on the required coating thickness). cut). And when fused, the suspension surface is applied to the cut surface to the desired surface, i.e. the film thickness that matches the surface obtained before undercutting and the surface of the suspension. . The fused suspension coating forms a strong metal bond, which can be applied from heating and cooling to the steel substrate in the same way as during quenching or when subjected to severe impact loads during service. There is no crushing.

  The connection fitting coated with the suspension may then optionally be tempered by quenching by quenching and tempering to the required overall hardness in order to increase the mechanical strength of the connection fitting. The substrate below the coated surface is optionally hardened again by induction quenching to increase the hardness of the substrate to HRC 50-55, which is higher than the overall hardness of the hardened and tempered steel of the fitting. Also good. This further increases the wear life of the connecting fitting. Therefore, the wear life of the coated fittings (by coreless and induction hardening) is the sum of the wear life of the suspension coating and the wear life of the induction hardened steel substrate under the coating. It's okay. Similar observations can be made on other coated and heat treated parts such as pin bushings and pins of pin-bush connection mechanisms, chassis trucks, chains, bottom rollers. This sum is considered to be 4 to 6 times the wear life of the uncoated metal parts, depending on the suspension coating thickness used. Normally, it appears that a coating with a thickness of 1-2 mm or more is not necessary to achieve the purpose of wear and corrosion. There is a tendency for macroscopic surface cracks to form in the coating during coreless or induction quenching, but the coating does not leave the substrate. This is because the coating is strongly metal bonded to the substrate. Cracks serve to relieve stress created during fusion of the coating. However, such cracks are less likely to be observed if the coated part is not heat treated (not quenched).

  In an exemplary embodiment, the wear resistant coating is substantially harder and more wear resistant than steel normally used for tools, gears, engine parts, farm equipment, etc., eg, 1045 grade hardened conditioned steel. It is a unique fused alloy. In addition, the wear resistant coating has a uniform density and is less brittle and more durable than those obtained with prior art such as Alessi US Patent No.Re.27,851 Preferably, the protective coating is substantially free of inclusions.

  Commonly owned U.S. Pat. The entire contents of US Pat. No. 5,879,743 are incorporated herein by reference, in which such wear resistant alloys are disclosed. In addition, suspension and coating techniques incorporating suspensions suitable for use in the present invention are disclosed. For example, the fusible cemented carbide in the exemplary embodiment is preferably 60% iron, or cobalt, or the eighth group transition metal of the periodic table, such as nickel. However, cemented carbide metal alloys may be based on other metals as long as they have the physical properties described above and form a metal bond, in this case a metal bond with an iron substrate. Minor components (about 0.1 to 20% by weight) are generally boron, carbon, chromium, iron (alloys based on nickel and cobalt), manganese, nickel (alloys based on iron and cobalt), There is at least one of silicon, tungsten, molybdenum, one or more carbide forming elements, and combinations thereof. Trace elements (less than about 0.1% by weight) such as sulfur may also be present as a minor contaminant. In an exemplary embodiment, the alloy has a Vickers hardness as high as 950 to 1250 HV. The hard metal alloy has a melting temperature lower than the melting point of the metal to be coated, for example about 1110 ° C. or less, preferably between about 900 ° C. and about 1200 ° C. and preferably about 1100 ° C. or less. It is preferable.

  Provided is a method of hardening and depositing a metal surface of a portion formed of a carburized metal or a non-carburized metal with an abrasion-resistant coating.

  In a preferred and typical method, carburized metal is removed from the metal surface portion to a depth sufficient to expose a non-carburized layer of metal prior to quenching. The metal may be removed by any suitable technique such as cutting, cutting, lathe, grinding, polishing. The exposed part defines the area to be covered. In an exemplary embodiment, the exposed portion is defined by the appearance of an annular groove, indentation, or other well or cavity having a radius that is smaller than the radius of the original metal surface. This area is then coated with a suspension of hard metal alloy and a metal bond is formed by fusing the hard metal alloy between the uncarburized layer and the coated unfused suspension, thereby A wear resistant coating is formed.

  Another typical method is to decarburize the surface over an appropriate amount of time to reduce the carbon from the surface of the metal part to the desired depth and, in the long run, remove the carbon, thereby removing the metal part. Prepare a surface, such as the surface of a track pin bush. In one embodiment, decarburization occurs in the surface layer to a depth such that subsequent metal bonding occurs only in non-carburized metal. For example, decarburization of the carburized layer occurs to a carbon level of 0.4 to 0.6 wt%, to a depth of 0.002 to 0.003 inches (50 to 75 microns). In another aspect, decarburization occurs up to 3.0 mm for a typical track pin bushing carburized to a depth of at least carburized layer + 0.5 mm, ie, 2.5 mm. In another aspect, the carburization depth is up to 0.010 inches and decarburization occurs up to 0.015 inches.

  In a further exemplary method, the surface of the metal part, i.e. the track pin bushing, the part of the pin bushing connection mechanism, the track chain bottom roller and the surface of the track chain coupling fitting is made of a hard metal alloy The surface or a part of the surface may be coated with the suspension. If the surface to be coated has been previously carburized, the carbon may be removed before applying the hard metal alloy by a heat treatment method, for example by decarburization or by removal of the carburized material, for example by cutting. A metal bond is thus formed between a selected portion of the surface of the metal part and the coated unfused suspension, thereby forming an abrasion resistant coating.

  In an example where the suspension is applied to a carburized substrate, for example, a carburized iron substrate that has a higher concentration of carbon on the surface layer than the inner layer, a metal bond between the carbon and the suspension is observed. Has been. In the metallurgical reaction, carbon from the substrate diffuses into the coating and increases the carbon content at the interface. The carbon increased at the interface lowers the melting point of the suspension alloy in the interface region, for example, the interface layer between the suspension alloy and the substrate, and as a result, the suspension alloy peels off. To alleviate this effect, the above procedure is used in which the non-carburized material is exposed. In another approach, the surface of the substrate to which the suspension is applied is allowed to flake off during the fusion time during fusion, for example for a few minutes at the fusion temperature (excluding temperature rise and cooling times). In order to minimize this, it is kept substantially horizontal, for example, in the range of 5 to 10 degrees from the horizontal.

  The suspension is aqueous and may be formed of a fusible hard metal alloy in powder form finely divided with polyvinyl alcohol (PVA). Examples of suitable suspensions are commonly owned US Pat. No. 5,879,743, the entire contents of which are incorporated herein by reference. As disclosed herein and in the 743 patent, the hard metal alloy may be an eighth group transition metal of the periodic table such as iron, or cobalt, or nickel, or an alloy thereof. Good. In an exemplary embodiment, the hard metal alloy is in the form of a finely divided powder with a particle size that is small enough to form a homogeneous suspension. Typical particle sizes range from about 90 mesh to about 400 mesh and may be finer than 400 mesh. If possible, the average particle size is finer than about 115 mesh and most preferably finer than about 200 mesh. The powder may be a mixture of powders of different particle sizes. Also, one or more suspending agents and one or more peptizers may optionally be added to the suspension.

  In addition, the suspension used is prepared by thoroughly mixing the powdered hard metal alloy with the polyvinyl alcohol binder solution to the desired alloy to binder solution weight ratio. In this regard, commonly owned U.S. Pat. No. 5,879,743, the entire contents of which are incorporated herein by reference. Other additives to the suspension may include suspending agents and peptizers.

  The suspension may be applied in any suitable manner. For example, spray coating, rotational molding, dipping, casting, spreading, ie application by brush or doctor blade may be used.

  In one exemplary embodiment of a method for hardening a metal surface with an abrasion resistant coating, a substantially homogeneous suspension of polyvinyl alcohol and finely divided powdered fusible hard metal alloy. An aqueous solution is formed and the metal surface is coated. The aqueous suspension is then dried, preferably by external heating, to form a solid layer of a fusible hard metal alloy in a polyvinyl alcohol matrix on the metal surface. The steps of applying the coating to the metal surface and drying the suspension to form a solid layer may be repeated one or more times to form a thicker suspension coating.

  In another exemplary embodiment of a method for hardening a metal surface with an abrasion resistant coating, the metal surface is coated with an aqueous polyvinyl alcohol solution, and a finely divided powdered fusible hard metal alloy is The aqueous polyvinyl alcohol solution is applied on the coating of the aqueous polyvinyl alcohol solution before drying. The steps of coating the metal surface, applying a fusible hard metal alloy, drying the mixture of polyvinyl alcohol, binder, alloy powder and forming a solid layer are repeated one or more times to form a thicker suspension A liquid coating may be formed.

  In an exemplary embodiment of the method of the present invention, suitable procedures for applying the suspension to the metal surface to be coated include the shape and size of the metal product having the metal surface, and polyvinyl for the cemented metal alloy. Depends on the concentration ratio of the alcohol binder solution. Usually, the unfused suspension is cast, brushed, or sprayed onto the metal surface to be protected, but products having the metal surface to be protected may be immersed in the unfused suspension.

  Dipping, casting, and application by brushing are convenient for forming a relatively thick coating in a short time, for example, 1 mm or more. The spraying can be repeated to form a thicker layer over a longer period of time. For these procedures, the ratio of hard metal alloy to polyvinyl alcohol solution preferably falls within the range of about 4: 1 to about 8: 1, and the concentration of polyvinyl alcohol solution is about 1% polyvinyl alcohol by weight. It is preferably up to 15%. For example, 0500/0250 and 0600/0250 or similar suspensions are suitable for this procedure. The designation xxx / yyyy indicates the parameters of the suspension, where xxx = weight ratio of powder alloy to polyvinyl alcohol and yyyy = wt% of polyvinyl alcohol present in the aqueous solution as a binder. Note that the decimal point after the first two digits is omitted in the display. Therefore, 0500 represents 5.0. In the case of a thick suspension composition, that is, when the ratio of the alloy is high with respect to the polyvinyl alcohol aqueous solution, it can be applied as a squeezable paste or can be bonded to the metal surface as a tape-like roll. For these procedures, the ratio of the hard metal alloy to the polyvinyl alcohol solution is in the range of about 8: 1 to about 15: 1, and the concentration of the polyvinyl alcohol solution is about 2% by weight of polyvinyl alcohol by weight. Preferably it is up to 15%. In the above procedure, special additives can serve as dispersants, suspending agents, plasticizers.

  In addition to the above method of applying the coating, the coating can also be thickened by a paste and tape method. However, it is difficult to adapt these procedures to high-speed manufacturing environments. Thus, when thick coatings are desired, a reliable and economical alternative to pastes and tapes is a multiple coating procedure that creates a coating with a uniform film thickness even on a large surface. A necessary film thickness can be created by repeatedly spraying while interposing a drying cycle in the middle. Drying may be performed between about 80 ° C. and about 100 ° C., for example, in a forced circulation air dryer. A suspension of 0500/0250 is particularly suitable for this method, but other formulations may be used.

  The film thickness of the coated unfused suspension can be adjusted by shrinkage factors to achieve the desired final film thickness after metal bonding. That is, the final film thickness may be either coplanar with the surface or diameter of the metal part, or may protrude from or retract from the surface diameter. For example, the suspension described herein has been found to have a draw coefficient of about 0.55 ± 0.05. Therefore, the thickness of the suspension before fusion is adjusted according to the cast-off factor, and the desired final thickness of the abrasion-resistant coating, for example, 1.67 times to 2.0 times the final thickness of the unfused suspension Layers can be used.

  Bonding is a metal bond between the dried suspension coating and the metal part, i.e. a selected part of the metal part, and a metal part with the carburized metal part removed to expose a decarburized or possibly non-carburized surface. Forming a metal bond with the selected portion. For example, a metal surface coated with a layer of fusible hard metal alloy in a polyvinyl alcohol substrate, or coated with a layer of fusible hard metal alloy using an aqueous polyvinyl alcohol solution, It can be heated to the fusion temperature of the hard metal alloy until the hard metal alloy is fused onto the metal surface under a protective atmosphere. In a controlled atmosphere, that is, an inert or reducing atmosphere, heating is performed with nitrogen excluded because the alloy is nitrided to inhibit alloy fusion. For example, a partial pressure of 100-500 μm with helium or argon in a vacuum furnace, or a mild positive pressure with water about a few inches above the atmospheric pressure with argon, helium, hydrogen in a belt furnace during fusion. Suitable for use. Thereafter, the metal surface fused with the hardfacing is cooled to ambient temperature.

  In one example of the bonding process, the track pin bushing is heated to about 1065 ° C to 1110 ° C. Heating takes place in a belt-type conveyor furnace with a hydrogen pressure slightly above atmospheric pressure and the track pin bushing is held at the desired fusion temperature for about 2 to 5 minutes and then cooled.

  In a further exemplary embodiment, after joining the metal parts to form a wear resistant coating, the remaining carburized metal of the metal parts can be cured to the desired hardness by quenching. For example, the remaining carburized metal can be cured by a heat treatment that increases the hardness compared to the non-carburized metal. In an exemplary embodiment where the metal part is a track pin bush, the remaining carburized metal is the inner surface of the track pin bush, the first end of the track pin bush, and the track pin bush. Corresponds to at least one of the second ends of the.

  Experiments were conducted to study the effect of carburization on suspension bond formation. A small low carbon steel track pin bush with a wall thickness of 10 mm was carburized and air cooled. The thickness of the carburized layer was about 2 to 2.5 mm. These samples were then reheated to 1600 ° F. for 1, 2, and 3 hours, respectively, in a decarburizing environment, ie, in a low carbon potential environment, with a film thickness of 0.0005 to 0.0007, respectively. 0.001 to 0.0012, 0.001 to 0.0015 inch decarburized layers were obtained. The decarburized sample was coated with a fusible hard metal alloy suspension and bonded according to the procedure outlined above. Further details of suspension coating and bonding are described in US Pat. No. 5,879,743, the contents of which are hereby incorporated by reference.

  Following coating and bonding, the steel / suspension interface was examined with an optical microscope. The longer the decarburization time, the better the integrity of the bond. This indicates that a steel alloy that has been decarburized to a deeper depth and a steel alloy with a low carbon content are likely to be combined with the suspension. However, in the bush, traces of the suspension coating flowing due to gravity were found during the fusion. However, the thicker the decarburized layer, the weaker the tendency to flow.

  These results indicate that decarburization may be performed prior to suspension coating to improve the binding results. However, there are at least two disadvantages to the decarburization process. Decarburizing on some surfaces (eg, decarburizing only the outer diameter, not the inner diameter and end faces) is impractical, and the time required for sufficient decarburization to occur, ie The time required for forming a suitable non-carburized layer on the object to be coated with the unfused suspension takes several hours or more, perhaps 7 to 10 hours, which is not economical.

  In a preferred method of implementation including removal of the carburized material, the carburized material is removed, for example, by cutting, cutting, turning, grinding, polishing, etc., exposing the non-carburized layer. In experiments corresponding to this method, the four track pin bushings were reduced in their outer diameters by cutting. The amount removed was 3.00, 3.35, 3.75, 4.00 mm, respectively. The sample was then coated and bonded to the exposed area with a hardened metal suspension according to the procedure outlined above.

  Visual inspection of the bond area found no gravity flow during fusion. Optical microscopy of the bush cross section revealed little or no inclusion in the interface bond region of the steel and suspension coating and good metal bonding for all samples. It was concluded that removal of the carburized layer sufficient to expose the non-carburized layer, in this case about 3 mm of material, but that removal therefore forms a good bond. This conclusion was further confirmed by a third experiment. In the experiment, carburized trucks, pins, and bushes were subjected to normalizing heat treatment. And the depth of 3 mm was cut from the outer diameter of the cross section of the cut bush. In the optical microscope inspection, the carburized layer was completely removed by this cutting, and the exposed surface had a microstructure corresponding to the pre-carburized microstructure.

  In further experiments on carburizing material removal, a track pin bushing with a 2 mm carburized case was cut to a depth of 2.5 mm on the axial length of the outer surface to remove the carburizing case and its extent Was coated with the suspension. The coating was done using a hand-held sprayer and manual fitting, resulting in a substantially uniform coating thickness. The manual fitting was similar to a spindle with the parts mounted axially and a manual crank for manual operation. However, it was possible to utilize automation techniques such as rotation by machine operation and computer control devices, that is, rotation devices, spraying devices, robotics and the like. The surface of the unfused suspension was then cut on a lathe to be smooth and concentric with the track pin bushing holes. The film thickness of the suspension before fusion was adjusted based on the shrinkage factor so that the fused film thickness was 1 mm or 1.5 mm. The shrinkage factor is a relationship derived from experiments in which the fused film thickness is about 0.55 times the unfused film thickness. As found after the fusion, this cutting also helped create a coating with a smooth surface and a uniform film thickness.

  Track pin bushings with cut and cooled surfaces were fused using an appropriate temperature-time (Tt) cycle. In an exemplary embodiment, the Tt cycle is performed in a controlled atmosphere in a vacuum or belt furnace, ie, an inert or reducing atmosphere, excluding nitrogen that nitrides the alloy. Good examples are the partial pressure of helium or argon in a vacuum furnace, or a mild positive pressure where water is about a few inches above the atmospheric pressure due to argon, helium, hydrogen in a belt furnace. To prevent the fused semi-fluid suspension metal from flowing downwards due to gravity, the track pin bushing is installed in the furnace chamber with the axis vertical and the maximum temperature and time at maximum temperature are Carefully selected and monitored.

  An example of a suitable T-t cycle is as follows. The track pin bushing is gradually heated from 10 to 15 ° C. to 1080 to 1110 ° C., maintained at that temperature for 1 to 5 minutes, preferably 1 to 2 minutes, and recirculated at the desired cooling rate, ie Use a blower to cool the track pin bushings. In another example of a suitable T-t cycle, the track pin bushing is heated at 8-10 ° C. per minute to 1065-1110 ° C.

  In a visual observation of a representative example of a track pin bush with a wear resistant coating prepared by a preferred practice method including removal of carburized material, the surface of the coating is the surface of the cut suspension prior to fusion. It became clear that the surface finish was smooth. In addition, the track pin bushings were fused and bonded to the substrate without any noticeable gravity flow. Measurements using a micrometer showed that the track pin bush did not experience any noticeable distortion. In subsequent investigations, track pin bushings with wear resistant coatings were ground using a silicon carbide grinding wheel, and the ground surfaces were inspected with an optical microscope. The abrasion resistant coating was not at all porous. Similarly, the cross-section of the coating examined with an optical microscope did not show any porosity at all inside the coating.

  An evaluation was also made of the wear resistance of the wear-resistant coatings used for trucks, pins and bushings. Rubber wheel sand abrasion tests revealed that the wear rate of the fused suspension coating was one-fourth to one-sixth that of quenched 1080 steel. Thus, 1/3 to 1/2 mm fused suspensions showed as much wear as a 2 to 3 mm thick layer of hardened 1080 steel as a first approximation.

As a result of the above series of experiments, the following generalized manufacturing procedure was determined for a track pin bushing coated with suspension and having a final outer diameter of D mm. This procedure involves selective removal of carburized material.
1. The track pin bushings are cut for each part drawing for a specific application and usage environment, except where the outer diameter is larger than the desired final outer diameter to allow for material removal. In the exemplary embodiment of the track pin bushing described herein, the outer diameter is D + 3.0 mm.
2. Carburize at least part of the truck pin bush.
3. Remove material from at least a portion of the carburized surface. In this example, the carburized surface is the outer surface. Therefore, at least a part of the outer diameter surface is removed so as to expose at least the non-carburized layer. Furthermore, the outer diameter may optionally be further reduced to match the desired film thickness of the abrasion resistant coating. In a preferred exemplary embodiment track pin bushing, at least a portion of the outer diameter after material removal is D-3.0 mm. This step therefore removes approximately 6 mm of material from the area on the carburized outer diameter surface.
4). The exposed surface of the track pin bushing is coated with a cemented carbide suspension to a film thickness (before fusion) that provides the desired outer diameter before fusion. For example, the exposed surface of the track pin bushing is coated to a film thickness of 2.75 mm, that is, a film thickness equal to the diameter of (D−3 mm) + 2.75 × 2. This corresponds to an outer diameter of D + 2.5 mm.
5. The suspension is fused to form a metal bond between the exposed non-carburized layer and the suspension. In the preferred embodiment of the track pin bushing described herein, the film thickness of the fused suspension is 2.75 × 0.55 or 1.5 mm, the final bushing diameter is D, That is, it was a desirable diameter. Here, factor 0.55 is an experimentally established contraction factor for the suspension coating thickness.

  In a more generalized procedure, with reference to FIG. 11, the following relationship was determined for the track pin bush:

R1 = R-X + Y + 0.5 Formula 1
R2 = RX Formula 2
R3 = R + 0.82X Formula 3
Where R is the final finishing radius of the track pin bushing, ie R = R2 + X, R1 is the outer radius of the carburized track pin bushing, and R2 is the carburized layer to expose the non-carburized layer. The outer radius of the track pin bush after removal, the cut depth is 0.5 mm greater than the carburization depth, ie R2 = R1-(Y + 0.5), R3 is after suspension coating Is the outer radius of the track pin bush before fusion, where X is the membrane of the suspension coating after fusion, assuming a shrinkage factor of 0.55 for suspension coating during the fusion process Thickness, that is, X = 0.55 (R3-R2), and Y is the thickness of the carburized layer. All units of measurement are in millimeters (mm).

  From the above, when the values of the film thickness X and the carburizing depth Y of the fused suspension layer are known from Equation 1 to Equation 3, the outer radius of the carburized track pin bushing, the outer radius after cutting, The outer radii after suspension coating but before fusion are each given with respect to the final track pin bush outer surface radius R.

  In another exemplary embodiment, the chassis assembly component with the wear-resistant coating by metal bonding is a separate component of the track pin / bush connection mechanism and the track pin / bush connection mechanism, such as the track pin and the track.・ Inner diameter of pin bush. FIG. 4 is a schematic perspective view of an assembled pin bushing connection mechanism including a track pin bushing with the track pin inserted into the hole. FIG. 5 is a schematic perspective view of the disassembled pin / bush connection mechanism. The track pin / bush connection mechanism has a mating surface that includes the outer surface of the pin and the inner diameter surface of the bush (or the surface of the hole).

In the present invention, the hole surface of the bush and the outer surface of the pin are coated harder than sand using the following steps.
1. The mating surfaces are cleaned and grit blasted and a suspension containing a high alloy iron-based powder or a powder with similar function is applied. Details are described in the prior patent (Revankar, 5,879,743, March 9, 1999).
2. The suspension coating is then cut to the required pre-fusion dimensions, taking into account the shrinkage of the coating during fusion, and then fused in a suitable furnace using a suitable fusion environment. Either a vacuum furnace using a partial pressure of argon or a belt furnace using hydrogen at a slight positive pressure is recommended.
3. The fused pins and bushings may be heat treated as necessary to maintain the mechanical properties required for the base steel. Pins and bushings with fused coatings (whether heat treated or not) are then cut to the required final dimensions. The base steel may be cut using a conventional cutting tool or cutting method. However, the coated surface requires at least a silicon carbide round grinder, preferably a diamond round grinder with an appropriate bond type and grit size, to produce a smooth bearing and sliding surface.

  Since the coating is metal-bonded to the base steel, there is no risk of the coating being unbonded even under the influence of the high contact load often found in heavy machinery. This advantage is not available from many of the currently available surface modification techniques.

  This coating, unlike many other coatings and platings, can be applied to any desired film thickness. In order to prolong the life of the connection mechanism accordingly, the coating can be made thicker. Uses the latest hardened coatings such as physical vapor deposition (3-5 microns), chemical vapor deposition (10-25 microns), chrome electroplating (5-50 microns) and electroless nickel plating (2-20 microns) There is a limit on the thickness of the thin film applied or the practical film thickness, so that it is not suitable for a long-term durable P / B connection mechanism introduced in the heavy machinery industry, for example.

  Suspension coatings can be easily applied to long bush holes and there are no line of sight limitations associated with PVD (physical vapor deposition) or thermal spray processes.

  The coating technique allows the parts to be heat treated after the coating has been fused, and does not compromise the coating or the bond between the substrate and the coating. Other surface coatings will most likely break during such heat treatment.

  Unlike the hard chrome plating, this coating process has no environmental regulations.

  The composition of the alloy is selected so that the fusion coating is much harder than the sand particles. Therefore, in this example, an alloy powder is used which is coated with a hardness of 800 to 1100 HV, which is much higher than the hardness of sand particles (average hardness is about 700 to 800 HV). Accordingly, sand particles that enter the P / B connection mechanism do not cause wear damage as much as damage that the same sand particles are likely to give to the carburized and quenched surface of the P / B connection mechanism currently in use. Fine sand particles are more likely to be polished than to significantly wear the coated surface. Since it is unlikely that the sand particles will damage the coating as fast as the carburized and hardened surface, the lubricating oil will not need to be cleaned as often. Since the wear of the coated surface is very slow, the life of the connection mechanism is expected to be significantly extended.

(Experimental research)
Cold rolled steel pipes OD-95.25 mm (3.75 inches) and ID-76.20 mm (3.00 inches) were cut to make long bushes of 4-50 mm and 2-100 mm. The holes in the bush were lightly cut to remove the mill scale (black skin) and coated with a suspension, ie the suspension disclosed herein. The “fresh” coating was then cut to form a smooth surface concentric with the bush axis. Based on the pre-established relationship between the film thickness of the unfused coating and the fused coating, the film thickness of the cut coating was varied to create fused coatings with different film thicknesses.

  Bushings with cut “fresh” coatings were placed in a belt-type hydrogen furnace with the axis vertical, and the coatings were successfully fused. The fused coating did not flow down the steel surface (substrate) due to gravity. Also, it did not shrink and peel off from the steel. The as-fused coated surface was smooth. The film thickness of the fused coating varied from 1.30 mm to 1.875 mm, depending on the “fresh” film thickness selected.

  Attempts to polish the fused coating of the bush holes using an aluminum oxide and silicon carbide round grinder have been unsuccessful. The material removal speed was too slow, and the round grinder seemed to be struggling with the cutting work and made a rattling sound. This indicated that the grit was not hard enough to cut efficiently into Gopalite. Next, a CBN grindstone was used. This proved to be suitable for polishing the coating. However, there was a tendency for “load increase”, and the polishing efficiency decreased with time. The diamond grindstone had the best results. The coating was cut at twice the speed of CBN without making a rattling noise. Diamond wheels are 15% more expensive than CBN, but are clearly preferred for production machining. Although larger diameter parts can advantageously take advantage of the greater kinetic energy of the wear particles, polishing of the outer diameter surface may be accomplished with a silicon carbide round grinder, but CBN and diamond are still preferred.

  In one exemplary embodiment of a method for hardening a metal surface with an abrasion resistant coating, a substantially homogeneous suspension of polyvinyl alcohol and a finely divided powdered fusible hard metal alloy is provided. A turbid aqueous solution is formed and the metal surface is coated. The aqueous suspension is then dried, preferably by external heating, to form a solid layer of a fusible hard metal alloy in a polyvinyl alcohol matrix on the metal surface. The steps of applying the coating to the metal surface and drying the suspension to form a solid layer may be repeated one or more times to form a thicker suspension coating.

  In another exemplary embodiment of a method for hardening a metal surface with an abrasion resistant coating, the metal surface is coated with an aqueous polyvinyl alcohol solution, and a finely divided powdered fusible hard metal alloy is The aqueous polyvinyl alcohol solution is applied on the coating of the aqueous polyvinyl alcohol solution before drying. The steps of coating the metal surface, applying a fusible hard metal alloy, drying the suspension or aqueous coating, and forming a solid layer are repeated one or more times to form a thicker suspension material coating. It may be formed.

  In an exemplary embodiment of the method of the present invention, suitable procedures for applying the suspension to the metal surface to be coated include the shape and size of the metal product having the metal surface, and polyvinyl Depends on the concentration ratio of the alcohol binder solution. Usually, the unfused suspension is cast, brushed, or sprayed onto the metal surface to be protected, but products having the metal surface to be protected may be immersed in the unfused suspension.

  For example, when metal parts such as bottom rollers, pin bushings, pin bushing connection pins, track and chain fittings are formed of medium carbon steel, the coated metal parts are hardened to harden the steel. It may be quenched. For example, in the case of 1045 steel, heat to about 840 ° C and quench at a quenching temperature, in this case 840 ° C, for a time that depends on the volume and thickness of the part, and in a suitable quenching medium, preferably in a liquid. It may be quenched. Quenched steel parts are made at a desired temperature between 250 ° C and 500 ° C to achieve the overall hardness required to increase the mechanical strength of the metal parts and increase the wear resistance of the body of the metal parts. Tempering may be performed. The substrate below the coated surface is optionally re-cured by induction quenching, and if necessary, the substrate hardness is increased to approximately HRC 50-55, which is higher than the overall hardness of the quenched and tempered roller. May be. Increasing the hardness of the coated base material further increases the wear life of metal parts such as roller contact surfaces and track / chain coupling metal contact surfaces and wear surfaces of metal components. Therefore, the wear life of the coated fittings (heated by coreless quenching followed by induction hardening) is the sum of the wear life of the suspension coating and the wear life of the steel substrate subjected to induction hardening under the coating. It is. This sum is 4 to 6 times or more than the wear life of uncoated and hardened metal parts, depending on the purpose of wear and corrosion. There is a tendency for macroscopic surface cracks to form in the coating during coreless or induction quenching, but the coating does not leave the substrate. This is at least in part because the coating is strongly metal bonded to the substrate. Cracks serve to relieve stress created during fusion of the coating. However, such cracks are not normally observed if the coated part is not heat treated (not quenched).

  In another aspect of the present disclosure, a PTA weld coating is applied to the chassis component. For example, the PTA weld coating is applied to track and chain fittings or bottom rollers, but the PTA weld coating is also applicable to other chassis components.

  FIG. 12 is a schematic perspective view of the first side of the track and chain coupling fitting, showing the area where the PTA weld coating is applied. In an exemplary embodiment, the track and chain fitting 1200 includes a body 1202 forged from medium carbon steel. Medium carbon steel contains boron, manganese, chromium, and balanced iron. The track and chain fitting 1200 has a mounting surface 1204 on the first end 1206 of the body 1202 and a contact surface 1208 on the second end 1210 of the body 1202. The mounting surface 1204 has at least one opening for the attachment device 1212, which can be attached to the attachment device in such a manner that the track and chain fitting cannot be removed from the shoe of the truck of the track type machine shown in FIG. There are accessory devices for mounting in a removable manner. The contact surface 1208 is opposite the mounting surface 1204 and has a substantially planar region 1214 that extends long along the second end to form a wear surface. Depending on the intended use, for example in a track crawler machine, the wear surface mechanically contacts the roller surface of the chassis track chain chain bottom roller.

  At least a portion of the wear surface, for example a portion 1220 of the substantially planar region 1214, has a groove 1230 in the body 1202 of the track and chain fitting 1200, for example, an undercut that extends from the wear surface into the forged body. Have. In an exemplary embodiment, the groove 1230 is completely or substantially filled with a PTA weld coating 1222. The outer surface of the weld coating coincides with the wear surface of the track / chain fitting. In other embodiments, the outer surface of the PTA weld coating protrudes from the remainder of the contact surface. As an example, the PTA weld coating has a film thickness of about 2 to 3 mm or less than 3 mm.

  It is not necessary for the PTA weld coating to remain defect free in order to provide a wear resistant coating. For example, the PTA weld coating may have surface cracks. However, due to the metal bond between the PTA weld coating and the forged body, the PTA coating remains attached to the forged body intact. In addition, surface cracks have already been found to help relieve stress that occurs during the welding process. Without being bound by any one theory, it is believed that cracks occur during the heat treatment of a component, for example during quenching of the component.

  In an exemplary embodiment, chassis components that are coated with PTA welding can be preheated to an effective temperature to reduce the temperature difference between the component and the coating to a desired level. The process of preheating the components can reduce the number of large cracks that are noticeable in the coating caused by cooling the components that remain coated after the welding process.

  In addition, the wear-resistant coating 1222 by metal bonding also does not perform any pre-cutting, such as pre-cutting to form an arrangement such as a groove 1230, and optionally remains tracked. -You may form directly on the outer surface of the chain coupling metal 1200.

  In another exemplary embodiment, the chassis assembly component having a wear-resistant coating by metal bonding is a chassis truck chain bottom roller. FIG. 13 is a schematic perspective view of a typical chassis truck, chain, bottom roller 1300, and shows a range where hardened is applied. In FIG. 13, the outer surface 1302 is shown. Outer surface 1302 has a substantially cylindrical region 1304 bounded axially and outwardly by a flange portion 1306. At least one flange portion 1306 is larger in diameter than the substantially cylindrical region 1304. Also shown is a mounting surface 1308 for installation on a truck of a truck-type machine. The substantially cylindrical region 1304 is adapted to contact the contact surface of the track and chain fitting, such as the upper rail surface of the chain fitting found on a portion of the track of the track type machine shown in FIG. Yes. During operation, a portion or all of the substantially cylindrical region 1304 and the flange portion 1306 are subject to wear, and thus a portion or all of the substantially cylindrical region 1304 and the flange portion 1306 are against it. Hardened.

  FIG. 14 is a schematic cross-sectional view of a chassis truck chain bottom roller 1300 with a hardfacing showing a substantially cylindrical region 1304, a flange portion 1306, and a mounting surface 1308. FIG. The portion 1320 and flange portion 1306 of the substantially cylindrical region 1304 have a PTA weld jacket 1322. Two variations of portion 1320 (A and B) are shown in FIG. 14, but multiple variations may be used, including those not shown. Further, FIG. 14 shows a bottom roller 1300 incorporating two different variations (A and B), but it should be understood that both are the same and both are different variations. May be combined.

  Portion 1320 with PTA weld coating 1322 is shown as a groove 1330 in body 1332 of a substantially cylindrical region 1304. In one exemplary embodiment, the groove 1330 is an undercut in the body of a substantially cylindrical region. In some embodiments, the groove 1330 is completely or substantially filled with a PTA weld coating 1322. The outer surface of the weld coating coincides with the contact surface of the chassis track, chain, bottom roller. In other embodiments, the outer surface of the PTA weld coating protrudes from the remainder of the contact surface. As an example, the PTA weld coating has a film thickness of about 2 to 3 mm or less than 3 mm.

  In addition, the PTA weld coating 1322 does not perform any pre-cutting, such as pre-cutting to form an arrangement range, such as a groove 1330, and optionally, as-formed chassis truck chain bottom May be applied directly to the outer surface 1302 of the roller 1300;

  In an exemplary embodiment, it is possible to have a PTA weld coating 1322 on any portion of the substantially cylindrical region 1304, including the entire length of one or more outer surfaces of the substantially cylindrical region 1304. is there. Further, in an exemplary embodiment, it is possible to have a PTA weld coating 1340 on any portion of the flange portion 1306, including the entire length of one or more outer surfaces of the flange portion 1306. When PTA weld jacket 1340 is included in any portion of flange portion 1306, PTA weld jacket 1340 is separate from PTA weld jacket 1322 associated with a substantially cylindrical region 1304 (shown as variation A). The PTA weld coating on the flange may be continuous with the PTA weld coating 1322 associated with the substantially cylindrical region 1304 and at least on the outer surface 1302. In addition, the PTA weld coating 1340 does not perform any pre-cutting, such as pre-cutting to form an arrangement range, such as a groove 1342, and optionally, as-formed chassis truck, chain, bottom, It may be applied directly to the outer surface 1302 of the roller 1300.

  Within this specification, an exemplary method is described for a track and chain coupling. However, it should be understood that the typical method can be applied to any component of a chassis system where a PTA weld surface is applied.

  In the modified manufacturing process of the proposed chassis component, for example, the truck / chain coupling bracket or chassis truck / chain / bottom roller described herein, only a small amount under the contact or wear surface of the chassis component ( Depending on the required wear coating thickness, it is usually 1 to 3 mm, or 1 to 2 mm, cut (undercut) and matches the desired surface, ie the surface obtained before the undercutting step A PTA weld coating is applied to the cut surface until it is thick. In one example, the film thickness is approximately 2 to 3 mm, or less than 3 mm. The PTA weld coating forms a strong metal bond and does not crush from the substrate when heated or cooled during the quenching process or when exposed to severe impact loads during service.

  In one embodiment, the chassis component is the truck and chain coupling described herein. Track and chain fittings typically have a body, a mounting surface at the first end of the body, and a contact surface at the second end of the body. The mounting surface has at least one opening for an attachment device, and the contact surface is opposite the mounting surface and includes a substantially planar region extending long along the second end. And at least a portion of the wear surface. The wear surface is in mechanical contact with the roller surfaces of the chassis track, chain, bottom roller.

  In another embodiment, the chassis component is a chassis truck chain bottom roller as described herein. The chassis track chain bottom roller typically has a bottom roller having at least one cylindrical portion and at least one flange having a diameter larger than the at least one cylindrical portion. The at least one cylindrical portion and at least a portion of the at least one flange portion have a wear surface. The wear surface is in mechanical contact with the contact surface of the track / chain fitting.

  After that, the connecting fitting provided with the PTA weld coating may optionally be tempered to the required overall hardness by performing quenchless quenching by rapid cooling in order to increase the mechanical strength of the connecting fitting. The substrate below the coated surface is optionally hardened again by induction quenching to increase the hardness of the substrate to at least HRC50, which is higher than the overall hardness of the hardened and tempered steel, or from HRC50 to 55. May be applied. This hardening further increases the wear life of the connecting fitting. Therefore, the wear life of a PTA welded and heat-treated fitting (by means of induction quenching and induction hardening) is the sum of the wear life of the PTA weld coating and the wear life of the steel substrate subjected to induction hardening under the coating. It may be. Similar observations can be made for other coated and heat treated parts such as chassis trucks, chains, bottom rollers. This sum is considered to be 4 to 6 times the wear life of the uncoated metal part, depending on the coating thickness used. Normally, it appears that a coating with a thickness of 1 to 2 mm or more is not necessary to achieve the purpose of preventing wear and corrosion. There is a tendency for macroscopic surface cracks to form in the coating during the centerless quenching or induction quenching process, but the coating does not leave the substrate. This is because the coating is strongly metal bonded to the substrate. The crack serves to reduce the stress formed during the welding process. Such cracks are less likely to be observed if the coated part is not heat treated (if not quenched).

  FIG. 15 is a flowchart of a process 1500 used to form a chassis component with a PTA welded surface according to an exemplary embodiment. These processing steps typically include forging the body of the chassis component using medium carbon steel 1510 and the interior of the body forged from the wear surface to expose the range of chassis components to be coated. PTA welding in a first heat treatment procedure comprising a step 1520 of removing the wear surface portion of the chassis component, a step 1530 of applying a PTA weld coating to the undercut, and a quenching and tempering step to form an undercut extending to A process 1540 for heat-treating the coated main body and a process 1550 for heat-treating the main body in a second heat treatment procedure including an induction hardening process are included.

  FIG. 16 is a photomicrograph showing a cross section of a portion of a chassis truck chain bottom roller having a PTA coating forming the top surface. This component has an area under the PTA coating that is affected by the heat resulting from the processing of the component.

  In an exemplary embodiment, the PTA coating can be applied in an automated process using a programmed welding robot. The robot can be programmed to apply a PTA coating to selected portions of the component. PTA coating does not require component masking. In addition, there is no need to use a fusion furnace in the PTA coating process. Thus, a selected portion of a large component can be PTA coated without heating the entire component to a high melting temperature, such as about 1100 ° C.

  As described above, in one exemplary embodiment, the PTA coating can be applied to the same component in combination with the suspension coating. For example, a suspension coating can be applied to a more complex surface than a PTA coating. Thus, such complex surfaces can be coated with a suspension coating while other surfaces can be coated with a PTA coating. Also, the suspension coating process may be faster than the PTA welding process.

  Although the invention has been described in connection with preferred embodiments, additions, deletions, modifications, substitutions, etc., not specifically described, depart from the spirit and scope of the invention as defined in the appended claims. It will be appreciated by those skilled in the art that it can be practiced without.

FIG. 2 shows the components of a typical endless truck including a truck pin bushing. It is a schematic perspective view of a track pin bush. It is a schematic sectional drawing of the axial direction of the track pin bushing which gave the hardfacing with the uniform outer diameter in the longitudinal direction. It is a schematic sectional drawing of the axial direction of the track pin bushing which gave the hardfacing which enlarged the radius in the center part. FIG. 3 is a schematic perspective view of an assembly pin / bush connection mechanism including a track pin / bush with a track pin inserted into a hole. It is a figure which shows the range which performed the hardening overlay of the bush connection mechanism. It is a schematic sectional drawing of the track pin bushing which gave the hardfacing. It is a schematic sectional drawing of the track pin which gave the hardfacing. It is a schematic perspective view of a chassis truck, a chain, a bottom, and a roller, and is a figure which shows the range which performed hardfacing. It is a schematic sectional drawing of the chassis truck chain chain bottom roller which gave the hardfacing. It is a schematic perspective view of the first side of the track and chain coupling fitting, and is a view showing a range where hardened is applied. FIG. 6 is a radial schematic cross-sectional view showing a change in radius during applying a hard overlay to a track pin bush by wear-resistant coating. FIG. 3 is a schematic perspective view of a first side of a track / chain coupling fitting, showing a range where hardened is applied. It is a schematic perspective view of a chassis truck, a chain, a bottom, and a roller, and is a figure which shows the range which performed hardfacing. It is a schematic sectional drawing of the chassis truck chain chain bottom roller which gave the hardfacing. 2 is a flow chart of processing steps for forming a chassis component with a plasma arc (PTA) weld surface. It is a microscope picture which shows the cross section of a part of chassis truck chain chain bottom roller which has PTA coating | cover.

Claims (7)

A method of manufacturing a chassis component,
Forging the body of the chassis component using medium carbon steel;
Removing the portion of the wear surface of the chassis component to form an undercut extending from the wear surface into the forged body for the purpose of exposing a range of chassis components to be coated;
Applying a PTA weld coating to the undercut;
A step of heat-treating a body provided with a PTA weld coating in a first heat treatment procedure, wherein the first heat treatment procedure includes quenching and tempering;
A step of heat-treating the main body in a second heat treatment procedure, wherein the second heat treatment procedure includes induction hardening , and
The chassis component is a track and chain coupling bracket comprising the main body, a mounting surface on the first end of the main body, and a contact surface on the second end of the main body,
The mounting surface comprises at least one opening for an accessory device;
The contact surface has a substantially planar region extending long along the second end and has at least a portion of the wear surface;
The method wherein the contact surface is opposite the mounting surface . The method of claim 1 , wherein the wear surface is configured to mechanically contact a roller surface of a chassis truck, chain, bottom roller. The chassis component is a bottom roller having at least one cylindrical portion and at least one flange having a diameter larger than the at least one cylindrical portion;
The method of claim 1 , wherein a portion of the at least one cylindrical portion and the at least one flange portion has a wear surface. 4. The method of claim 3 , wherein the wear surface is configured to mechanically contact a contact surface of a track and chain fitting.   The method of claim 1, wherein the medium carbon steel includes boron, manganese, chromium, and balanced iron.   The method of claim 1, wherein the second induction heat treatment cures the body to a hardness of at least HRC50.   The method of claim 1, wherein the second induction heat treatment hardens the body to a hardness of HRC 50-55.

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