machine component

Abstract

Machine component that includes: a carrier material (100) consisting of a first metal; and a coating (90) arranged in contact with the carrier material (100) and covering at least part of a surface of the carrier material (100), wherein the coating (90) comprises: a matrix (95) consisting of a second metal; as well as hard particles (91) dispersed in the matrix (95); wherein: in an area that includes an interface between the coating (90) and the substrate (100), the coating (90) includes a projection (99) that extends towards the substrate (100); and in the projection (99) a part of a hard particle (91) is included, the hard particle (91) is not in contact with the support material (100), the center of the hard particle (91) is outside the projection (99) and the projection (99) has a depth that is smaller than the radius of the hard particle (91).

Description

Technical field

[0001] The present invention relates to machine components, in particular a machine component which contains a coating comprising hard particles dispersed in a matrix. Technical background

[0002] A coating can be applied to a machine component to improve wear resistance and for other purposes. Coatings that can be used to improve wear resistance include coatings containing hard particles dispersed in a matrix, for example, made of steel. Such a coating can be applied, for example, by weld overlay (see, for example, JP 2008 - 000 763 A and JP H08 - 47 774 A).

[0003] US 5,755,299 A addresses hard coating processes for improving the durability of deep drilling tools, particularly drill bits. It describes a hard coating layer consisting of a metallic matrix in which coated diamond particles are embedded and which is applied to metal surfaces to prevent erosion and abrasion. This publication states that hard materials, including tungsten carbide, are incorporated into the matrix and metallurgically bonded to the base, emphasizing the role of the coated diamond particles in improving wear resistance.

[0004] US Patent 6,138,779 A describes a hard coating material reinforced by coated ceramic particles, specifically cubic boron nitride, within a matrix layer. This technique significantly improves the wear resistance of rotary taper bits under harsh drilling conditions. The innovation lies in metallurgically bonding these superhard particles to the matrix, optimizing the hard coating for specific environments, and extending the service life of the drilling tools.

[0005] US 2009 / 0019783A1 addresses the problem of segregation of wear-resistant particles in coating layers and proposes a method for uniform distribution. This method utilizes particles coated with metals such as Fe, Co, Ni, or Cu to improve compatibility with the molten weld pool. This prevents particle settling, ensures uniform distribution, and improves the durability of the wear-resistant coating layer throughout the structure. Summary of the invention: Technical problem

[0006] If the coating detaches during use of the machine component, the wear resistance of the machine component will be impaired. Therefore, it is preferable to prevent the coating from detaching from the machine component that has the coating.

[0007] One object of the present invention is to improve the wear resistance of a machine component by preventing the coating from peeling off. Solution to the problem

[0008] A machine component according to the present invention comprises a substrate material consisting of a first metal and a coating arranged in contact with the substrate material and covering at least a portion of the substrate material's surface. The coating contains a matrix consisting of a second metal and hard particles dispersed in the matrix. In a region enclosing an interface between the coating and the substrate material, the coating includes a projection extending towards the substrate material. A portion of a hard particle is embedded in the projection. The hard particle is not in contact with the substrate material. The center of the hard particle is located outside the projection. The projection has a depth that is less than the radius of the hard particle.

[0009] In the machine component of the present invention, the coating in the area encompassing the interface between the coating and the substrate material includes a projection that extends towards the substrate material. This projection creates an anchoring effect, preventing the coating from detaching from the substrate material and thereby improving the wear resistance of the machine component. Thus, in the machine component of the present invention, it is possible to improve the wear resistance of the machine component.

[0010] In the machine component according to the present invention, a portion of the hard particle is incorporated into the projection. This reliably prevents the coating from detaching from the substrate material.

[0011] The machine component described above can be used as a part of a crawler track undercarriage, as an excavator tooth, or as a crusher tooth. This component, which exhibits excellent wear resistance, is suitable for applications requiring high wear resistance. Effects of the invention

[0012] As can be seen from the description above, the machine component of the present invention makes it possible to improve the wear resistance of the machine component by preventing the coating from peeling off. Brief description of the drawings Fig. Figure 1 is a schematic representation showing the structure of a caterpillar track vehicle; Fig. Figure 2 is a schematic representation illustrating the function of a drive wheel and bushings; Fig. Figure 3 is a schematic perspective view showing the structure of a socket; Fig. Figure 4 is a schematic top view showing the contact state of the drive wheel and a bushing; Fig. Figure 5 is a schematic sectional view along line VV in Fig. 4; Fig. Figure 6 is a schematic sectional view showing the structure of a coating on its surface and in its vicinity; Fig. 7 is a schematic sectional view showing the structure at and near an interface between the coating and a substrate material; Fig. Figure 8 is a flowchart that schematically represents a process for manufacturing a machine component; Fig. Figure 9 is a schematic perspective view illustrating a method for manufacturing a drive wheel; Fig. Figure 10 is a schematic perspective view illustrating the process for manufacturing the drive wheel; Fig. Figure 11 is a schematic sectional view illustrating a method for forming a coating; Fig. Figure 12 is a schematic perspective view illustrating the process for manufacturing the drive wheel; Fig. Figure 13 is a schematic perspective view illustrating the process for manufacturing the drive wheel; Fig. Figure 14 is a schematic perspective view illustrating a method for manufacturing a bushing; Fig. Figure 15 is a schematic perspective view illustrating the process for manufacturing the bushing; Fig. Figure 16 is a schematic perspective view showing the construction of a bucket of a hydraulic excavator; Fig. Figure 17 is a schematic top view showing the structure of a tooth; Fig. 18 is a schematic sectional view along the line XVIII-XVIII in Fig. 17; Fig. Figure 19 is a schematic sectional view showing the structure of a tooth of a comparative example; Fig. Figure 20 is a schematic sectional view illustrating a method for manufacturing a tooth; Fig. Figure 21 is a schematic sectional view illustrating the process for manufacturing the tooth; Fig. Figure 22 is a schematic perspective view showing the construction of a crusher; Fig. Figure 23 is a schematic perspective view showing the structure of an outer tooth of a fixed section of the crusher; Fig. 24 is a schematic sectional view along line XXIV-XXIV in Fig. 23; Fig. 25 is a schematic sectional view along line XXV-XXV in Fig. 24; Fig. Figure 26 is a schematic perspective view illustrating a method for manufacturing an outer tooth of the fixed section of a crusher; Fig. Figure 27 is a schematic perspective view illustrating the process for manufacturing the outer tooth of the stationary section of the crusher; Fig. Figure 28 is a schematic sectional view illustrating the process for manufacturing the outer tooth of the stationary section of the crusher; Fig. Figure 29 is a schematic sectional view illustrating the process for manufacturing the outer tooth of the stationary section of the crusher; Fig. Figure 30 is a schematic perspective view illustrating the process for manufacturing the outer tooth of the stationary section of the crusher; Fig. Figure 31 is a schematic perspective view illustrating the process for manufacturing the outer tooth of the stationary section of the crusher; Fig. Figure 32 is a schematic sectional view illustrating the process for manufacturing the outer tooth of the stationary section of the crusher; Fig. Figure 33 is a schematic sectional view illustrating the process for manufacturing the outer tooth of the stationary section of the crusher; Fig. 34 is a photograph showing a cross-section of a tooth; Fig. Figure 35 is an optical micrograph showing a surface of a coating and its surroundings (example); Fig. Figure 36 is an optical micrograph showing a surface of a coating and its surroundings (comparative example); Fig. 37 is an optical micrograph showing an interface between a coating and a substrate material and its surroundings (example); and Fig. Figure 38 is an optical micrograph showing an interface between a coating and a substrate material and its surroundings (comparative example). Description of embodiments

[0013] Embodiments of the present invention are described below. In the following drawings, the same or corresponding parts are identified by the same reference numerals, and their description is not repeated. First embodiment

[0014] A machine component according to a first embodiment, which is an embodiment of the present invention, is described using a drive wheel and bushings of a crawler track driving device as examples. Fig. Figure 1 is a schematic representation showing the structure of a caterpillar track vehicle. Fig. Figure 2 is a schematic representation illustrating the function of a drive wheel and bushings. Fig. Figure 3 is a schematic perspective view showing the structure of a socket. Fig. 4 and Fig. Figure 5 are schematic sectional views showing the contact state of the drive wheel and a bushing.

[0015] A tracked driving device 1 in the present embodiment, as described in Fig. Figure 1 shows a driving device for a working machine, such as a bulldozer, and includes a track 2, a track frame 3, a deflection wheel 4, a drive wheel 5, and a plurality (in this case seven) of running rollers 10 and a plurality (in this case two) of support rollers 11.

[0016] The caterpillar track 2 comprises a multitude of caterpillar track links 9 connected in an endless configuration, as well as caterpillar plates 6 attached to the corresponding caterpillar track links 9. The caterpillar track links 9 include outer links 7 and inner links 8. The outer links 7 and the inner links 8 are connected alternately.

[0017] The deflection pulley 4, the multiple track rollers 10, and the multiple support rollers 11 are mounted on the crawler track frame 3 in such a way that they can be rotated about their respective axes. The drive sprocket 5 is located at one end of the crawler track frame 3. A power source, such as a motor, is connected to the drive sprocket 5, and the drive sprocket 5 rotates about its axis, driven by the power source. A multiple of projections 51 are arranged on an outer circumferential surface of the drive sprocket 5, projecting radially outwards. The projections 51 engage with the crawler track 2. The rotation of the drive sprocket 5 is thus transmitted to the crawler track 2. The crawler track 2, driven by the rotation of the drive sprocket 5, rotates in a circumferential direction.

[0018] The deflection pulley 4 is attached to the other end (opposite the end where the drive wheel 5 is located) of the track frame 3. Furthermore, the track rollers 10 and the support rollers 11 are attached to the track frame 3 in the area enclosed between the drive wheel 5 and the deflection pulley 4, respectively, on the side in contact with the ground and on the side opposite the side in contact with the ground. The outer circumferential surfaces of the deflection pulley 4, the track rollers 10, and the support rollers 11 each come into contact with the inner circumferential surface of the track 2. This causes the track 2, driven by the rotation of the drive wheel 5, to rotate circumferentially and be guided by the deflection pulley 4, the drive wheel 5, the track rollers 10, and the support rollers 11.

[0019] An outer member 7 and an inner member 8, which are adjacent to each other, are, as with reference to Fig. As shown in Figure 2, the inner link 8 is connected by means of a connecting bolt 12 and a bushing 13. Each inner link 8 has two through holes 15, which are designed to extend in a direction perpendicular to the plane of rotation of the track 2. One and the other of these two through holes 15 are formed at one end and the other end, respectively, in the longitudinal direction of the link. Each outer link 7 has two through holes 15, which are designed to extend in a direction perpendicular to the plane of rotation of the track 2. One and the other of these two through holes 15 are formed at one end and the other end, respectively, in the longitudinal direction of the link.

[0020] The socket 13 has, as with reference to Fig. Figure 3 shows the shape of a hollow cylinder. The bushing 13 has a smaller diameter section 139 at each end, which has a smaller outer diameter. The bushing 13 has an inner circumferential surface 133 that has a constant diameter along its length. The thickness of the bushing 13 is reduced in the smaller diameter sections 139.

[0021] Paired outer members 7 are, as with reference to Fig. 2 and Fig. As shown in Figure 3, the inner links 8 are arranged such that their two through-holes 15 are aligned when viewed in the direction perpendicular to the plane of rotation of the track 2. Paired inner links 8 are arranged such that their two through-holes 15 are aligned when viewed in the direction perpendicular to the plane of rotation of the track 2. An outer link 7 and an inner link 8 adjacent to each other are arranged such that a through-hole 15 of the outer link 7 and a through-hole 15 of the inner link 8 are aligned when viewed in the direction perpendicular to the plane of rotation of the track 2. A bushing 13 is arranged such that it is enclosed between a pair of inner links 8 and the smaller-diameter section 139 at each end is inserted into a through-hole 15 of the corresponding inner link 8.A connecting bolt 12 is arranged such that it extends through the through holes 15 of the outer and inner links 7 and 8, which are adjacent to each other, the holes being aligned in the direction perpendicular to the plane of rotation of the caterpillar track 2, and it extends through the space enclosed by the inner circumferential surface 133 of the corresponding bushing 13. The connecting bolt 12 is arranged such that it extends longitudinally through the bushing 13.

[0022] The drive wheel 5 rotates in a circumferential direction, its outer circumferential surface 53 engaging with the outer circumferential surfaces 131 of the bushings 13 that form the track 2. The outer circumferential surface 53 of the drive wheel 5 and the outer circumferential surfaces 131 of each bushing 13 must therefore exhibit high wear resistance. The drive wheel 5 is a machine component that slides relative to another component or the bushing 13, thereby making contact with the bushing 13 or the outer circumferential surface 53. The bushing 13 is a machine component that slides relative to another component or the drive wheel 5, thereby making contact with the drive wheel 5 or the outer circumferential surface 131.

[0023] The drive wheel 5 contains, as with reference to Fig. 4 and Fig. Figure 5 shows a carrier material 50, which consists of metal (steel), and a coating 52, which covers the carrier material 50 and thus forms the outer circumferential surface 53, which is the contact area. The outer circumferential surface 53, which is the surface of the coating 52, has been smoothed. The state in which the outer circumferential surface 53, i.e., the surface of the coating 52, is smoothed refers to the state in which the surface profile, which arose from surface tension and the like during the formation of the coating 52 in the liquid state, has been removed from the surface of the coating 52. In the present embodiment, the outer circumferential surface 53, which is the surface of the coating 52, is a forged surface. The outer circumferential surface 53, orThe surface of the coating 52, which arose during the formation of the coating 52 in the liquid state due to surface tension and the like, was smoothed by forging. The metal forming the carrier material 50 can be, for example, carbon steel for use in mechanical engineering or alloy steel for use in mechanical engineering, specified according to the JIS standard (e.g., S45C or SCM435, as well as manganese steel (SMn), chromium steel (SCr), or chromium-molybdenum steel (SCM), which contains an equivalent amount of carbon).

[0024] A bushing 13 comprises a carrier material 134 and a coating 132, which covers the carrier material 134 and thus forms the outer circumferential surface 131, which is the contact area. The outer circumferential surface 131, which is the surface of the coating 132, has been smoothed. In the present embodiment, the outer circumferential surface 131, which is the surface of the coating 132, is a forged surface. The outer circumferential surface 131, or the surface of the coating 132, which was influenced by surface tension and the like during the formation of the coating 52 in the liquid state, has been smoothed by forging. The metal forming the carrier material 134 can be, for example, carbon steel for use in mechanical engineering or alloy steel for use in mechanical engineering, specified according to the JIS standard (e.g.,S45C or SCM435, as well as manganese steel (SMn), chromium steel (SCr) or chromium-molybdenum steel (SCM), which contains an equivalent amount of carbon), can be used.

[0025] In the drive wheel 5 and the bushings 13, which are the machine components in the present embodiment, the surfaces of the coatings 52 and 132, which form the contact areas, have been smoothed. This prevents a localized increase in contact pressure and other phenomena, so that the components cause less damage to the other components (bushings 13 and drive wheel 5).

[0026] The following is a description of the structure of a coating formed on the drive wheel 5 and the bushings 13. Fig. Figure 6 is a schematic sectional view showing the structure of a coating on its surface and in its vicinity. Fig. Figure 7 is a schematic sectional view showing the structure at and around an interface between the coating and a substrate material. A coating 90 (coating 52 and coating 132), formed on the drive wheel 5 and the bushings 13, contains, as described with reference to Fig. 6 and Fig. Figure 7 shows a matrix 95 consisting of a second metal and hard particles 91 dispersed in matrix 95. The second metal forming matrix 95 can, for example, be a mixture of a metal derived from a welding wire and the metal (first metal) forming the carrier material 100 (carrier material 50 and carrier material 134). The hard particles 91 can be particles with a higher hardness than matrix 95, such as sintered carbide particles. The coating 90 exhibits higher wear resistance than the carrier material 100.

[0027] The surface 90A of the coating 90, as described in Fig. Figure 6 shows a forged surface. The hard particles 91, located in a surface region 90B of the coating, which is an area within one average particle diameter of the hard particles 91 from the surface 90A of the coating 90, are embedded in the coating 90 and arranged side by side. This prevents the hard particles 91 from protruding significantly from the surface 90A of the coating 90. This, in turn, prevents the hard particles 91 from falling out during use of the drive wheel 5 and the bushings 13, thereby improving the wear resistance of the drive wheel 5 and the bushings 13.It should be noted that the average particle diameter of the hard particles 91 can be determined by examining a cross-section perpendicular to the surface 90A of the coating 90 with a light microscope and calculating an average of the diameters of ten hard particles 91 examined.

[0028] The hard particles 91 located in the surface area 90B of the coating can, as in Fig. Figure 6 shows that the hard particle 91 is arranged in contact with the surface 90A of the coating 90. This reduces the area of ​​a hard particle 91 exposed at the surface 90A of the coating 90, thus preventing the hard particle 91 from falling out.

[0029] Of the hard particles 91, which are located in the surface area 90B of the coating, as shown in Fig. As shown in Figure 6, each hard particle 91 that has an area exposed at the surface 90A of the coating 90 has an acute central angle θ (of less than 90°) corresponding to this exposed area. This reduces the area of ​​a hard particle 91 exposed at the surface 90A of the coating 90, thus preventing the hard particle 91 from falling out.

[0030] In an area that includes an interface between the coating 90 and the substrate material 100, as described with reference to Fig. Figure 7 shows the coating 90 with projections 99 that extend onto the substrate 100. The projections 99 create an anchoring effect that prevents the coating 90 from detaching from the substrate 100. This results in improved wear resistance of the drive gear 5 and the bushings 13. Each projection 99 encloses at least a portion of a hard particle 91. This more reliably prevents the coating 90 from detaching from the substrate 100. The matrix 95 of the coating 90 is located between the substrate 100 and the hard particle 91 enclosed in the projection 99. The hard particle 91 enclosed in the projection 99 is not in contact with the substrate 100. The center of the hard particle 91 is located outside the projection 99 (i.e., a portion of the hard particle 91, comprising less than half its volume, is enclosed within the projection 99).A hard particle 91 is contained within a projection 99. Each projection 99 has a depth that is smaller than the radius of the hard particle 91 contained within the projection 99.

[0031] A method for manufacturing a drive wheel 5, which is the machine component in the present embodiment, is described below with reference to Fig. 8 to 13 described. Fig. Figure 8 is a flowchart that schematically illustrates a process for manufacturing a drive wheel, which is the machine component. Fig. 9, Fig. 10, Fig. 12 and Fig. Figure 13 are schematic perspective views illustrating the process for manufacturing the drive wheel. Fig. Figure 11 is a schematic sectional view illustrating a method for forming a coating.

[0032] In the method for manufacturing a drive wheel 5 in the present embodiment, first, as described with reference to Fig. As can be seen in Figure 8, a step in the production of a support element is carried out as step S10. In this step S10, as described in reference to Fig. Figure 9 shows a carrier element 61, which becomes a support material 50 of the drive wheel 5. The carrier element 61 consists of a metal that forms the support material 50. The carrier element 61 has a cylindrical shape. The carrier element 61 includes a pair of end faces 61B and a side face 61A that connects the end faces 61B.

[0033] Subsequently, a step to form a coating is executed as step S20. In this step S20, as described in reference to Fig. 9 and Fig. As shown in Figure 10, a coating 63 is formed such that it covers part of the side surface 61A of the support element 61 manufactured in step S10. The coating 63 is formed over its entire longitudinal extent in the longitudinal direction of the support element 61. The coating 63 is also formed in a portion of the circumferential direction (approximately half) of the support element 61. The coating 63 has a structure in which beads 62, extending in the longitudinal direction of the support element 61, lie adjacent to one another in the circumferential direction without gaps between them.

[0034] The coating 63 can, for example, be formed by overlay welding using CO2 arc welding, as described below. First, a device for forming a coating is described. The device for forming a coating contains, as referenced in Fig. Figure 11 shows a welding torch 70 and a nozzle 80 for feeding hard particles. The welding torch 70 contains a welding nozzle 71, which has the shape of a hollow cylinder, and a contact tip 72, which is located inside the welding nozzle 71 and connected to a power source (not shown). A welding wire 73, which is in contact with the contact tip 72, is continuously fed to the side of the front end of the welding nozzle 71. JIS YGW12, for example, can be used for the welding wire. A gap between the welding nozzle 71 and the contact tip 72 is a flow path for shielding gas. The shielding gas flowing through the flow path is expelled from the front end of the welding nozzle 71. The nozzle 80 for feeding hard particles has the shape of a hollow cylinder. Inside the nozzle 80 for feeding hard particles, hard particles 91 are fed in and ejected via the front end of the nozzle 80 for feeding hard particles.

[0035] This device for forming a coating can be used to form a coating 63 using the method described below. With a carrier element 61 serving as one electrode and the welding wire 73 as the other electrode, voltage is applied across the carrier element 61 and the welding wire 73. This generates an arc 74 between the welding wire 73 and the carrier element 61. The arc 74 is shielded from the ambient air by the shielding gas, which is expelled from the front end of the welding nozzle 71 along the direction indicated by arrows β. Carbon dioxide, for example, can be used as the shielding gas. The heat in the arc 74 melts part of the carrier element 61 and also melts the front end of the welding wire 73. The melted front end of the welding wire 73 forms droplets that are transferred to the molten area of ​​the carrier element 61.This creates a melt pool 92, which is a liquid region in which the molten support element 61 and the molten welding wire 73 are mixed together. The hard particles 91, ejected via the nozzle 80 for the purpose of supplying hard particles, are fed into this melt pool 92.

[0036] When the welding torch 70 and the nozzle 80, which supply hard particles forming the device for cladding, move relative to the carrier element 61 in the direction indicated by arrow α, the position at which the molten pool 92 is formed shifts accordingly. The previously formed molten pool 92 solidifies, forming a bead 62. The bead 62 contains a matrix 95, which is formed by the solidification of the molten pool 92, as well as hard particles 91 dispersed in the matrix 95. A plurality of such beads 62 are formed side by side in the width direction without a gap between them, so that a desired area on the side surface 61A of the carrier element 61 is covered, thus completing the formation of the coating 63 (see Fig. 10) It should be noted that weld overlay can be carried out, for example, under the following conditions: welding current of 230 A, welding voltage of 17 V, feed rate of 110 g / min, and bead overhang of 4 mm. JIS YGW11 can be used as the welding wire. WC or W2C-based particles can be used as the hard particles.

[0037] Subsequently, a hot forging step is performed as step S30. In this step S30, the carrier element 61 with the coating 63 formed in step S20 is hot forged. The carrier element 61 with the coating 63 formed on it is then, as described in [reference to] Fig. 10 and Fig. As shown in Figure 12, the component is heated to a temperature that enables hot forging and then placed in a mold for forging, the mold having a cavity corresponding to a desired shape of the drive wheel 5. In the present embodiment, a plurality of arc-shaped parts forming an annular drive wheel 5 are produced by hot forging. The resulting parts are assembled in a subsequent step to produce the annular drive wheel 5. The coating 63 formed in step S20 is processed by hot forging. The carrier element 61 is hot forged such that the coating 63 covers the outer circumferential surface of the drive wheel 5. This produces a coating 52 that has a smooth surface from which the surface profile resulting from surface tension in the liquid state and the like has been removed. As shown in Figure 12, the hot forging process removes the surface profile resulting from surface tension in the liquid state. Fig. 12 shown, ridge 59 formed. Subsequently, as with reference to Fig. 12 and Fig. 13 shows that punching was carried out to remove the burr 59, so that a part is created that forms the drive wheel 5 (see Fig. 13).

[0038] When the carrier element 61 with the coating 63 formed on it is hot-forged, as described with reference to Fig. 11 and Fig. As can be seen in Figure 6, hard particles 91, which protrude from a surface of the coating 63 during its formation (beads 62), are pressed into the coating 63 (beads 62). As a result, in the drive wheel 5, the hard particles 91 located in the surface region 90B of the coating are embedded in the coating 90 and arranged side by side. The hard particles 91 located in the surface region 90B of the coating are in contact with the surface 90A of the coating 90. Of the hard particles 91 located in the surface region 90B of the coating, each hard particle 91 that has a region exposed at the surface 90A of the coating 90 has an acute central angle θ (of less than 90°) corresponding to the exposed region. This prevents the hard particle 91 from falling out during use of the drive wheel 5, thereby improving the wear resistance of the drive wheel 5.

[0039] When the carrier element 61 with the coating 63 formed on it is hot-forged, projections 99 are formed in the coating 90 due to the hard particles 91 that were located near the interface between the coating 63 (beads 62) and the carrier element 61 at the time of the coating 63's formation. At least a portion of a corresponding hard particle 91 is incorporated into each projection 99. The process described above simultaneously forms the surface area of ​​the coating 90, which exhibits excellent wear resistance because the hard particles 91 are in contact with the surface 90A, and the projections 99, which prevent the coating 90 from detaching from the carrier material 100.

[0040] Subsequently, as with reference to Fig. As shown in Figure 8, a heat treatment step is carried out as step S40. In this step S40, the drive wheel 5 (the part forming the drive wheel 5), produced by hot forging in step S30, undergoes heat treatment. The heat treatment carried out in step S40 consists, for example, of tempering. This gives the carrier material 50 of the drive wheel 5 the desired hardness and toughness. Subsequently, in order to mount the drive wheel 5 onto a support body (not shown), an area where no coating 90 has been formed is machined to improve dimensional accuracy, create a mounting hole, etc. The drive wheel 5 (the part forming the drive wheel 5) in the present embodiment is thus completed.

[0041] In the above-described method for manufacturing the drive wheel 5, the projections 99 are formed in the coating 90. The anchoring effect of the projections 99 prevents the coating 90 from detaching from the substrate 100. This leads to improved wear resistance of the drive wheel 5. At least a portion of a corresponding hard particle 91 is incorporated into each projection 99. This more reliably prevents the coating 90 from detaching from the substrate 100.

[0042] The following refers to Fig. 8, Fig. 14 and Fig. 15 a method for manufacturing a bushing 13 which is the machine component in the present embodiment is described. Fig. Figure 8 is a flowchart that schematically illustrates a process for manufacturing a bushing. Fig. 14 and Fig. Figure 15 are schematic perspective views illustrating the method for manufacturing the bushing. The bushing 13 in the present embodiment can be manufactured using a similar method to the drive wheel 5 described above.

[0043] In the method for manufacturing a bushing 13 in the present embodiment, as described with reference to Fig. As can be seen in Figure 8, the first step in manufacturing a support element is performed as step S10. In this step S10, as described in Figure 8, the following steps are carried out: Fig. Figure 14 shows a carrier element 64, which becomes a carrier material 134 of the bushing 13. The carrier element 64 consists of a metal that forms the carrier material 134. The carrier element 64 has a cylindrical shape. The carrier element 64 includes a pair of end faces 64B and an outer circumferential surface 64A that connects the end faces 64B.

[0044] Subsequently, a step to form a coating is executed as step S20. In this step S20, as described in reference to Fig. 14 and Fig. As shown in Figure 15, a coating 63 is formed such that it covers part of the outer circumferential surface 64A of the support element 61 formed in step S10. The coating 63 is formed in the central section in the longitudinal direction of the support element 64. No coating 63 is formed in the longitudinal direction of the support element 64 at either end section. The coating 63 is formed over the entire surface in the circumferential direction of the support element 64. The coating 63 has a structure in which beads 62, extending in the longitudinal direction of the support element 64, lie next to each other in the circumferential direction without gaps between them. The coating 63 can be formed, for example, by overlay welding using CO2 arc welding, as described above in the manufacture of the drive wheel 5.It should be noted that the coating 63 can be formed in a part in the circumferential direction of the carrier element 64, which corresponds to the area that comes into contact with the drive wheel 5, for example over half of the circumference.

[0045] Subsequently, a hot forging step is performed as step S30. In this step S30, the carrier element 64 with the coating 63 formed in step S20 is hot forged. The carrier element 64 with the coating 63 formed on it is then, as described in section Fig. 15 as well Fig. As shown in Figures 3 to 5, the component is heated to a temperature suitable for hot forging and then placed in a mold for forging. The mold has a cavity corresponding to the desired shape of the bushing 13. The coating 63 formed in step S20 is processed by hot forging. The carrier element 64 is hot forged such that the coating 63 covers the outer circumferential surface 131 of the bushing 13. This produces a coating 132 with a smooth surface, where the surface profile resulting from surface tension in the liquid state, etc., has been removed. The two longitudinal ends of the carrier element 64, where no coating 63 has been formed, become the smaller-diameter sections 139 of the bushing 13. Subsequently, a bolt hole is formed into which a connecting bolt 12 is inserted to join the links 7 and 8 (see Figure 3). Fig. 2) The bolt hole is, as described in reference to Fig. 3 can be seen, formed by the inner circumferential surface 133 and extends in the axial direction.

[0046] When the carrier element 64 with the coating 63 formed on it is hot-forged, hard particles 91, which protrude from a surface of the coating 63 during its formation (beads 62), are pressed into the coating 63 (beads 62). As a result, in the bushing 13, the hard particles 91 located in the surface region 90B of the coating are embedded in the coating 90 and arranged side by side. The hard particles 91 located in the surface region 90B of the coating are in contact with the surface 90A of the coating 90. Of the hard particles 91 located in the surface region 90B of the coating, any hard particle 91 that has a region exposed at the surface 90A of the coating 90 has an acute central angle θ (of less than 90°) corresponding to the exposed region.This prevents the hard particle 91 from falling out during use of the bushing 13, thereby improving the wear resistance of the bushing 13.

[0047] When the carrier element 64 with the coating 63 formed on it is hot-forged, projections 99 are formed in the coating 90 of the bushing 13 due to the hard particles 91 that were located near the interface between the coating 63 (beads 62) and the carrier element 64 at the time of the coating 63 formation. At least a portion of a corresponding hard particle 91 is incorporated in each projection 99.

[0048] Subsequently, as with reference to Fig. As shown in Figure 8, a heat treatment step is carried out as step S40. In this step S40, the bushing 13, produced by hot forging in step S30, undergoes heat treatment. The heat treatment carried out in step S40 consists, for example, of tempering. This gives the carrier material 134 of the bushing 13 the desired hardness and toughness. Subsequently, the smaller diameter sections 139 of the bushing 13 are machined to improve dimensional accuracy, reduce surface roughness, etc. The bushing 13 in the present embodiment is thus completed.

[0049] In the above-described method for manufacturing the bushing 13, the projections 99 are formed in the coating 90. The anchoring effect of the projections 99 prevents the coating 90 from detaching from the substrate 100. This results in improved wear resistance of the bushing 13. At least a portion of a corresponding hard particle 91 is incorporated into each projection 99. This more reliably prevents the coating 90 from detaching from the substrate 100. Second embodiment

[0050] A machine component according to a second embodiment, which is a further embodiment of the present invention, is described below using an excavator tooth of a hydraulic excavator as an example. Fig. Figure 16 is a schematic perspective view showing the construction of a bucket of a hydraulic excavator. Fig. Figure 17 is a schematic top view showing the structure of a tooth. Fig. 18 is a schematic sectional view along the line XVIII-XVIII in Fig. 17.

[0051] A spoon 201 in the present embodiment, as described in Fig. The bucket 201, shown in Figure 16, is attached to the front end of a boom (not shown) of a hydraulic excavator and is used for excavating earth and sand. The bucket 201 contains a main body 210, which consists of a plate-like element and has an opening, a multitude (in which the Fig. Figure 16 shows a bucket 201 with three teeth 220 attached to the main body 210 such that they partially project from a circumference 212 of the opening of the main body 210 on its excavation side, and an attachment section 230 located on a side of the main body 210 opposite the side to which the teeth 220 are attached. The bucket 201 is supported by the boom of the hydraulic excavator via the attachment section 230. When the bucket 201 is used for excavation work, the teeth 220 are the first to penetrate soil and sand. The teeth 220 must therefore exhibit high abrasion resistance (wear resistance) to soil and sand.

[0052] A tooth 220 contains, as in Fig. Figure 17 shows a front end 221 and a rear end 222. The tooth 220 is attached to the main body 210 at the side of its rear end 222, with the side at its front end 221 projecting from the circumference 212 of the opening of the bucket 201. In operation, the tooth 220 is in contact with another component, namely the main body 210. The bucket 201 penetrates soil and sand through the side of the front end 221 of the tooth 220. Therefore, the side of the front end 221 of the tooth 220 must exhibit particularly high resistance to abrasion from soil and sand.

[0053] A tooth 220 contains, as with reference to Fig. Figure 18 shows a substrate material 225, consisting of a first metal, and a coating 227, which is in contact with the substrate material 225 and covers a covered area 225A that is part of a surface of the substrate material 225. The first metal for the substrate material 225 can be, for example, carbon steel for use in mechanical engineering or alloy steel for use in mechanical engineering, specified according to the JIS standard (e.g., S45C or SCM435, as well as manganese steel (SMn), chromium steel (SCr), or chromium-molybdenum steel (SCM), which contains an equivalent amount of carbon).In a boundary region 229 of the coating, which corresponds to a boundary between the covered region 225A and an exposed region 225B, which corresponds to a region outside the covered region 225A on the surface of the substrate material 225, the exposed region 225B and a surface 227A of the coating 227 are flush with each other and form a forged surface. The surface 227A of the coating 227 corresponds entirely to the forged surface.

[0054] Fig. Figure 19 is a schematic sectional view showing the structure of a tooth with a coating as a comparative example. When forming a coating to improve wear resistance on or near the front end of a tooth, the coating is typically formed on a steel substrate of a desired shape. Tooth 920 of the comparative example, which is a typical tooth with a coating, contains, as referenced in Fig. Figure 19 shows a front end 921 and a rear end 922. A coating 927 is formed on the side of the front end 921 of the tooth 920. The coating 927 is formed, for example, by weld overlay to cover a covered area 925A of a substrate material 925 that has been shaped as desired. Thus, at edge sections 929A, 929B, which correspond to the boundaries between the covered area 925A and exposed areas 925B, 925C outside the covered area 925A, steps are formed between the exposed areas 925B, 925C and a surface 927A of the coating 927. These steps increase the resistance of the tooth 920 when penetrating soil and sand. Furthermore, the coating 927 is formed after the substrate material 925 has been shaped. It is difficult to form the coating 927 near the front end 921.Thus, in the area encompassing the front end 921, the exposed area 925C of the front end is formed, which is not covered by the coating 927. This exposed area 925C of the front end, which has low wear resistance, accelerates wear and increases the frequency of tooth replacement 920.

[0055] In the case of tooth 220 in the present embodiment, as with reference to Fig. As can be seen in Figure 18, the exposed area 225B and the surface 227A of the coating 227 are flush with each other in the edge region 229 of the coating. This prevents an increase in penetration resistance that would otherwise be caused by a step in the edge region 229 of the coating. If the edge region 229 of the coating is enclosed in the forged surface, the machining step required to make the exposed area 225B and the surface 227A of the coating 227 flush with each other can be omitted. Therefore, machining the edge region 229 of the coating, where the hardness difference is significant, and machining the coating 227, which has a high hardness, can be avoided. Thus, in the present embodiment of the tooth 220, it is possible to avoid a disadvantage that would otherwise occur during the formation of the coating 227.Furthermore, a coating can be formed on a carrier element, and forging can then be carried out to form an area that encloses the front end 221. This allows the area enclosing the front end 221 to be shaped as shown in . Fig. 18 shown, easily covered with the coating 227, and a tooth 220 can be produced which has high wear resistance.

[0056] The coating 90 (coating 227), which is formed on the tooth 220, contains, as described with reference to Fig. 6 and Fig. Figure 7 shows how, in the first embodiment described above, the drive wheel 5 and the bushing 13 have a matrix 95 consisting of a second metal, as well as hard particles 91 dispersed in the matrix 95. The second metal forming the matrix 95 can, for example, be a mixture of a metal derived from a welding wire and a metal (first metal) forming the carrier material 100 (carrier material 225). The hard particles 91 can be particles with a higher hardness than the matrix 95, such as sintered carbide particles. The coating 90 exhibits higher resistance to abrasion from soil and sand (wear resistance) than the carrier material 100.

[0057] The surface 90A of the coating 90, as described in Fig. Figure 6 shows a forged surface. The hard particles 91, located in a surface region 90B of the coating, which is an area within an average particle diameter of the hard particles 91 from the surface 90A of the coating 90, are embedded in the coating 90 and arranged side by side. This prevents the hard particles 91 from protruding significantly from the surface 90A of the coating 90. This, in turn, prevents the hard particles 91 from falling out during use of the tooth 220, thereby improving the wear resistance of the tooth 220.

[0058] The hard particles 91 located in the surface area 90B of the coating can, as in Fig. Figure 6 shows that the hard particle 91 is arranged in contact with the surface 90A of the coating 90. This reduces the area of ​​a hard particle 91 exposed at the surface 90A of the coating 90, thus preventing the hard particle 91 from falling out.

[0059] Of the hard particles 91, which are located in the surface area 90B of the coating, as shown in Fig. As shown in Figure 6, each hard particle 91 that has an area exposed at the surface 90A of the coating 90 has an acute central angle θ (of less than 90°) corresponding to this exposed area. This makes the area of ​​a hard particle 91 exposed at the surface 90A of the coating 90 small, thus preventing the hard particle 91 from falling out.

[0060] The coating 90 contains, as referenced in Fig. Figure 7 shows projections 99 in an area that includes an interface between the coating 90 and the substrate 100. These projections extend onto the substrate 100. The projections 99 create an anchoring effect that prevents the coating 90 from detaching from the substrate 100. This results in improved wear resistance of the tooth 220. Each projection 99 incorporates at least a portion of a hard particle 91. This more reliably prevents the coating 90 from detaching from the substrate 100. The matrix 95 of the coating 90 is located between the substrate 100 and the hard particle 91 incorporated into the projection 99. The hard particle 91 incorporated into the projection 99 is not in contact with the substrate 100. The center of the hard particle 91 is located outside the projection 99 (i.e.,A portion of the hard particle 91, which has a volume of less than half that of the particle, is contained within the projection 99. Each projection 99 has a depth that is less than the radius of the hard particle 91 contained within the projection 99.

[0061] A procedure for producing a tooth 220 is described below. Fig. Figure 8 is a flowchart that schematically represents a process for manufacturing a tooth, which is the machine component. Fig. 20 and Fig. Figure 21 are schematic sectional views illustrating the process for manufacturing the tooth.

[0062] In the method for manufacturing a tooth 220 in the present embodiment, as described with reference to Fig. As can be seen in Figure 8, the first step in manufacturing a support element is performed as step S10. In this step S10, as described in Figure 8, the following steps are carried out: Fig. As can be seen in Figure 20, a support element 250 is manufactured, which becomes a support material 225 of the tooth 220. The support element 250 consists of a first metal. The support element 250 has a cylindrical shape. The support element 250 has a cylindrical shape that includes one end face 252, another end face 253, and a side face 251 that connects one end face 252 and the other end face 253. A first chamfered section 252A is formed in a region where one end face 252 and the side face 251 are connected. A second chamfered section 253A is formed in a region where the other end face 253 and the side face 251 are connected. The side of one end face 252 of the support element 250 corresponds, as with reference to Figure 20, to the shape of the end face 252 of the support element 250. Fig. 20 and Fig. 18 can be seen, the side of the front end 221 of the tooth 220, and the side of the other end surface 253 of the support element 250 corresponds to the side of the rear end 222 of the tooth 220.

[0063] Subsequently, a step to form a coating is executed as step S20. In this step S20, as described in reference to Fig. 20 and Fig. As can be seen in Figure 21, a coating 260 is formed in contact with a covered area 251A, which is part of a surface of the support element 250 manufactured in step S10, in order to cover the covered area 251A. The coating 260 is designed to cover a desired area of ​​the support material 225 when hot forging is performed, as described below. The covered area 251A can be determined in advance by simulating the hot forging process, for example, using a finite element method. In the present embodiment, as with reference to Fig. As can be seen in Figure 21, the coating 260 is designed to cover the side of one end surface 252 of the side surface 251, the first chamfered section 252A, and one end surface 252. The coating 260 can be formed by overlay welding using CO2 arc welding, as in the first embodiment described above.

[0064] Subsequently, a hot forging step is performed as step S30. In this step S30, the carrier element 250 with the coating 260 formed in step S20 is hot forged. The carrier element 250 with the coating 260 formed on it is then, as described in section Fig. 21 and Fig. As shown in Figure 18, the tooth 220 is heated to a temperature that allows hot forging and then placed in a mold for forging. The mold has a cavity corresponding to the desired shape of the tooth 220. This hot forging processes an area of ​​the carrier element 250 that includes an edge section 259 of the coating. Through hot forging, the edge section 259 of the coating becomes the edge section 229 of the coating of the tooth 220. With the edge section 259 of the coating processed during hot forging, the tooth 220 is produced, which has the exposed area 225B and the surface 227A of the coating 227, which are flush with each other, in the edge section 229 of the coating.In the edge section 229 of the coating, the exposed area 225B and the surface 227A of the coating 227 form a flush forged surface corresponding to the area of ​​the die used in hot forging, in which the edge section 259 of the coating is machined. In the edge section 229 of the coating, the exposed area 225B and the surface 227A of the coating 227 form a flush surface corresponding to the shape of the die used for forging. The edge section 229 of the coating is enclosed within the forged surface.

[0065] When the carrier element 250 with the coating 260 formed on it is hot-forged, hard particles 91, which protruded from a surface of the coating 260 during its formation, are pressed into the coating 260. As a result, in the tooth 220, the hard particles 91 located in the surface region 90B of the coating are embedded in the coating 90 and arranged side by side. The hard particles 91 located in the surface region 90B of the coating are in contact with the surface 90A of the coating 90. Of the hard particles 91 located in the surface region 90B of the coating, any hard particle 91 that has a region exposed at the surface 90A of the coating 90 has an acute central angle θ (of less than 90°) corresponding to the exposed region (see Fig. 6) This prevents the hard particle 91 from falling out during the use of tooth 220, thereby improving the wear resistance of tooth 220.

[0066] When the carrier element 250 with the coating 260 formed on it is hot-forged in tooth 220, projections 99 are formed in the coating 90 due to the hard particles 91 that were located near the interface between the coating 260 and the carrier element 250 at the time the coating 260 was formed. At least a portion of a corresponding hard particle 91 is incorporated in a projection 99 (see Fig. 7).

[0067] Subsequently, as with reference to Fig. As shown in Figure 8, a heat treatment step is performed as step S40. In this step S40, the tooth 220, produced by hot forging in step S30, undergoes heat treatment. The heat treatment performed in step S40 consists, for example, of tempering. This imparts the desired hardness and toughness to the base material 225 of the tooth 220. The tooth 220 is finished in the present embodiment using the method described above.

[0068] In the above-described method for manufacturing tooth 220, the projections 99 are formed in the coating 90. The anchoring effect of the projections 99 prevents the coating 90 from detaching from the substrate 100. This results in improved wear resistance of the tooth 220. At least a portion of a corresponding hard particle 91 is incorporated into each projection 99. This more reliably prevents the coating 90 from detaching from the substrate 100. Third embodiment

[0069] In the following, a machine component according to a third embodiment, which is a further embodiment of the present invention, is described using a tooth of a crusher as an example. Fig. Figure 22 is a schematic perspective view showing the construction of a crusher. Fig. Figure 23 is a schematic perspective view showing the structure of an outer tooth of a fixed section of the crusher. Fig. 24 is a schematic sectional view along line XXIV-XXIV in Fig. 23. Fig. 25 is a schematic sectional view along line XXV-XXV in Fig. 24.

[0070] A crusher 301 in the present embodiment, as described in Fig. The crusher 301, shown in Figure 22 and attached to the front end of a pole of a machine, is used for crushing concrete or other materials. The crusher comprises a main frame 310, a fixed section 320 attached to the main frame 310, and a movable section 330 rotatably mounted on the main frame 310 so that it can be opened and closed relative to the fixed section 320. The movable section 330 is connected to a hydraulic cylinder (not shown) located within the main frame 310. Driven by the hydraulic cylinder, the movable section 330 rotates, thus opening and closing relative to the fixed section 320.

[0071] The stationary section 320 has a front end to which a plurality (in the present embodiment, three) of outer teeth 321 of the stationary section are spaced apart from one another. A crusher plate 322 is positioned on the stationary section 320 in the area opposite the movable section 330 when the movable section 330 is closed relative to the stationary section 320. The crusher plate 322 has a plurality of through holes formed therein, and recesses 323 are formed in the areas of the stationary section 320 that are exposed via the respective through holes. The movable section 330 has a front end to which a plurality (in the present embodiment, two) of outer teeth 331 of the movable section are spaced apart from one another.In the movable section 330, a plurality of internal teeth 333 of the movable section are arranged in the area opposite the stationary section 320 when the movable section 330 is closed relative to the stationary section 320. When the movable section 330 is closed relative to the stationary section 320, the two outer teeth 331 of the movable section each engage in the two spaces formed by the three outer teeth 321 of the stationary section. When the movable section 330 is closed relative to the stationary section 320, the internal teeth 333 of the movable section engage in the corresponding recesses 323 in the stationary section 320.In the crusher 301, which is constructed as follows, concrete or other materials to be crushed are fed between the moving section 330 and the stationary section 320 in the state where the moving section 330 is open relative to the stationary section 320, and then the moving section 330 is closed relative to the stationary section 320, so that the materials are crushed. When the materials are crushed, the outer teeth 321 of the stationary section, the outer teeth 331 of the moving section, and the inner teeth 333 of the moving section come into direct contact with the concrete or other materials to be crushed. The outer teeth 321 of the stationary section, the outer teeth 331 of the moving section, and the inner teeth 333 of the moving section, which are the teeth of the crusher, must therefore exhibit high wear resistance.To improve wear resistance, coatings can be applied to the teeth of the crusher, specifically to the outer teeth 321 of the stationary section, the outer teeth 331 of the moving section, and the inner teeth 333 of the moving section. The structure of an outer tooth 321 of the stationary section is described below as an example of a crusher tooth.

[0072] An outer tooth 321 of the fixed section has, as with reference to Fig. Figure 23 shows a front end surface 321A, which is a flat surface on the side of the front end; a rear end surface 321D, which is a flat surface on the side of the rear end; a first side surface 321B, which is a flat surface connecting the front end surface 321A and the rear end surface 321D and which is said to face the side of the movable section 330; a second side surface 321E, which is a curved surface connecting the front end surface 321A and the rear end surface 321D and which is arranged opposite the first side surface 321B; and two third side surfaces 321C, each of which is a flat surface connecting the front end surface 321A and the rear end surface 321D and also connecting the first side surface 321B and the second side surface 321E. The outer tooth 321 of the fixed section is attached to the fixed section 320 at the rear end face 321D.

[0073] The outer tooth 321 of the fixed section contains, as with reference to Fig. 24 and Fig. Figure 25 shows a substrate material 325, consisting of a first metal, and a coating 327, which is in contact with the substrate material 325 and covers a portion of its surface. The coating 327 covers the entire extent of the front end face 321A and a portion of each of the first side face 321B, the second side face 321E, and the third side face 321C. Larger portions of the surface of the first side face 321B and the second side face 321E are covered by the coating 327 than those of the third side face 321C. No coating 327 is formed on the rear end face 321D. For the first metal forming the substrate material 325, carbon steel for mechanical engineering applications or alloy steel for mechanical engineering applications, specified according to the JIS standard (e.g.,S45C or SCM435, as well as manganese steel (SMn), chromium steel (SCr) or chromium-molybdenum steel (SCM), which contains an equivalent amount of carbon), can be used.

[0074] The coating 90 (coating 327), which is formed on the outer tooth 321 of the fixed section, contains, as described with reference to Fig. 6 and Fig. Figure 7 shows that, as in the first embodiment described above, the drive wheel 5 and the bushings 13 consist of a matrix 95 made of a second metal and hard particles dispersed in the matrix 95. The second metal forming the matrix 95 can, for example, be a mixture of a metal derived from a welding wire and the metal (first metal) forming the carrier material 100 (carrier material 325). The hard particles 91 can be particles with a higher hardness than the matrix 95, such as sintered carbide particles. The coating 90 exhibits higher wear resistance than the carrier material 100.

[0075] The surface 90A of the coating 90, as described in Fig. Figure 6 shows a forged surface. The hard particles 91, located in a surface region 90B of the coating, which is an area within one average particle diameter of the hard particles 91 from the surface 90A of the coating 90, are embedded in the coating 90 and arranged side by side. This prevents the hard particles 91 from protruding significantly from the surface 90A of the coating 90. This, in turn, prevents the hard particles 91 from falling out during use of the outer tooth 321 of the fixed section, thereby improving the wear resistance of the outer tooth 321 of the fixed section.

[0076] The hard particles 91 located in the surface area 90B of the coating can, as in Fig. Figure 6 shows that the hard particle 91 is arranged in contact with the surface 90A of the coating 90. This reduces the area of ​​a hard particle 91 exposed at the surface 90A of the coating 90, thus preventing the hard particle 91 from falling out.

[0077] Of the hard particles 91, which are located in the surface area 90B of the coating, as shown in Fig. As shown in Figure 6, each hard particle 91 that has an area exposed at the surface 90A of the coating 90 has an acute central angle θ (of less than 90°) corresponding to this exposed area. This makes the area of ​​a hard particle 91 exposed at the surface 90A of the coating 90 small, thus preventing the hard particle 91 from falling out.

[0078] In an area that includes an interface between the coating 90 and the substrate material 100, as described with reference to Fig. Figure 7 shows the coating 90 with projections 99 that extend onto the substrate 100. The projections 99 create an anchoring effect that prevents the coating 90 from detaching from the substrate 100. This leads to improved wear resistance of the outer tooth 321 of the fixed section. Each projection 99 encloses at least a portion of a hard particle 91. This more reliably prevents the coating 90 from detaching from the substrate 100. The matrix 95 of the coating 90 is located between the substrate 100 and the hard particle 91 enclosed in the projection 99. The hard particle 91 enclosed in the projection 99 is not in contact with the substrate 100. The center of the hard particle 91 is located outside the projection 99 (i.e., a portion of the hard particle 91, comprising less than half its volume, is enclosed within the projection 99).A hard particle 91 is contained within a projection 99. Each projection 99 has a depth that is smaller than the radius of the hard particle 91 contained within the projection 99.

[0079] The following describes a procedure for producing an outer tooth 321 of the fixed section. Fig. Figure 8 is a flowchart that schematically illustrates a procedure for manufacturing an outer tooth of the stationary section that is the machine component. Fig. 26 and Fig. Figure 27 are perspective views illustrating a method for manufacturing an outer tooth of the stationary section of a crusher. Fig. 28 and Fig. Figure 29 are schematic sectional views illustrating the process for manufacturing the outer tooth of the stationary section of the crusher. Fig. 28 is a schematic sectional view along line XXVIII-XXVIII in Fig. 27. Fig. 29 is a schematic sectional view along line XXIX-XXIX in Fig. 28. Fig. 30 and Fig. Figure 31 are schematic perspective views illustrating another method for manufacturing the outer tooth of the stationary section of the crusher. Fig. 32 and Fig. Figure 33 are schematic sectional views illustrating the other method for manufacturing the outer tooth of the stationary section of the crusher. Fig. 32 is a schematic sectional view along line XXXII-XXXII in Fig. 31. Fig. 33 is a schematic sectional view along line XXXIII-XXXIII in Fig. 32.

[0080] In the method for manufacturing an outer tooth 321 of the stationary section in the present embodiment, first, as with reference to Fig. As can be seen in Figure 8, a step in the production of a support element is carried out as step S10. In this step S10, as described in reference to Fig. Figure 26 shows a carrier element 350 manufactured, which becomes a carrier material 325 of the outer tooth 321 of the fixed section. The carrier element 350 consists of a first metal. The carrier element 350 has a cylindrical shape, which includes a first end face 350A, a second end face 350D and a side face 350F.

[0081] Subsequently, a step to form a coating is executed as step S20. In this step S20, as described in reference to Fig. As shown in Figures 27 to 29, a coating 360 is formed to cover the first end surface 350A and an area on the side of the first end surface 350A of the side surface 350F of the carrier element 350 manufactured in step S10. As in the first embodiment, the coating 360 can be formed with a plurality of beads 362. The first end surface 350A is completely covered by the coating 360. No coating 360 is formed on the second end surface 350D. On the side surface 350F, an area within a predetermined distance in the axial direction from the area connected to the first end surface 350A is covered with the coating 360. Although the coating 360 on the side surface 350F has a substantially uniform length in the axial direction, it has a shorter length in paired areas that are symmetrical with respect to the central axis.Corresponding to these areas, projecting exposed areas 350G are formed on the side surface 350F, which are not covered with a coating and project towards the first end surface 350A. The coating 360 can be formed by overlay welding using CO2 arc welding, as in the first embodiment described above.

[0082] Subsequently, a hot forging step is performed as step S30. In this step S30, the carrier element 350 with the coating 360 formed in step S20 is hot forged. The carrier element 350 with the coating 360 formed on it is then, as described in section Fig. 27 to 29 as well Fig. 24 and Fig. As shown in Figure 25, the part is heated to a temperature that allows hot forging and then placed in a mold for forging. The mold has a cavity that corresponds to a desired shape of the outer tooth 321 of the fixed section. The hot forging processes the coating 360 formed in step S20. The hot forging creates the first end face 350A and the second end face 350D areas that correspond to the front end face 321A and the rear end face 321D, respectively, of the outer tooth 321 of the fixed section.On the side surface 350F, the areas in the circumferential direction where the projecting exposed areas 350G have been formed become the third side surfaces 321C of the outer tooth 321 of the fixed section, and the areas outside the areas where the projecting exposed areas 350G have been formed become the first side surface 321B and the second side surface 321E of the outer tooth 221 of the fixed section.

[0083] When the carrier element 350 with the coating 360 formed on it is hot-forged, hard particles 91, which protruded from a surface of the coating 360 during its formation, are pressed into the coating 360. As a result, the hard particles 91 located in the surface region 90B of the coating are embedded in the coating 90 and arranged side by side on the outer tooth 321 of the stationary section. The hard particles 91 located in the surface region 90B of the coating are in contact with the surface 90A of the coating 90 (see Fig. 6) Of the hard particles 91 located in the surface area 90B of the coating, any hard particle 91 that has an area exposed at the surface 90A of the coating 90 has an acute central angle θ (of less than 90°) corresponding to the exposed area. This prevents the hard particle 91 from falling out during use of the outer tooth 321 of the fixed section, thereby improving the wear resistance of the outer tooth 321 of the fixed section.

[0084] When the carrier element 350 with the coating 360 formed on it is hot-forged, projections 99 are formed in the coating 90 of the outer tooth 321 of the fixed section due to the hard particles 91 that were located near the interface between the coating 360 and the carrier element 350 at the time the coating 360 was formed. At least a portion of a corresponding hard particle 91 is incorporated in a projection 99 (see Fig. 7).

[0085] Subsequently, as with reference to Fig. As shown in Figure 8, a heat treatment step is performed as step S40. In this step S40, the outer tooth 321 of the stationary section, produced by hot forging in step S30, undergoes heat treatment. The heat treatment performed in step S40 consists, for example, of tempering. This imparts the desired hardness and toughness to the base material 325 of the outer tooth 321 of the stationary section. Subsequently, the areas where no coating 360 has been formed are machined to improve dimensional accuracy, etc. The outer tooth 321 of the stationary section in the present embodiment is thus completed.

[0086] In the above-described method for producing the outer tooth 321 of the fixed section, the projections 99 are formed in the coating 90.

[0087] The anchoring effect of the projections 99 prevents the coating 90 from detaching from the substrate 100. This leads to improved wear resistance of the outer tooth 321 of the outer section. At least part of a corresponding hard particle 91 is incorporated into each projection 99. This more reliably prevents the coating 90 from detaching from the substrate 100.

[0088] It should be noted that in the steps described above, to facilitate hot forging after the formation of coating 360, preforms can be made before the formation of coating 360. That is, a carrier element 350, which has a cylindrical shape, is formed as described with reference to Fig. 26 and Fig. Figure 30 shows that the first end surface 350A is manufactured in step S10, and then the side of the first end surface 350A undergoes preforming. This preforming brings the first end surface 350A into a rectangular shape, and forms first chamfered sections 350B and second chamfered sections 350C, which are connected to the long sides and short sides of the first end surface 350A, respectively.

[0089] Then, in step S20, as with reference to Fig. As can be seen in Figures 31 to 33, a coating 360 is formed such that it covers the first end surface 350A, the first chamfered sections 350B, and the second chamfered sections 350C of the preformed support element 350. The first end surface 350A is completely covered with the coating 360. No coating 360 is formed on the second end surface 350. The coating 360, which extends in the axial direction, is in the areas that extend over the first chamfered sections 350B (see Figure 31 to 33). Fig. 33), longer than in the areas extending over the second chamfered sections 350C (see Fig. 32). Then, in step S30, hot forging is performed so that the first end face 350A and the second end face 350D become the areas corresponding to the front end face 321A and the rear end face 321D of the outer tooth 321 of the fixed section, respectively. The areas where the coating 360 is short in the axial direction become the third side faces 321C of the outer tooth 321 of the fixed section, and the areas where the coating 360 is long become the first side face 321B and the second side face 321E of the outer tooth 321 of the fixed section.

[0090] In each of the methods for manufacturing the machine components in the first to third embodiments, as described above, a surface section of the carrier element corresponding to the area where the coating is to be formed can be removed beforehand when forming the coating on the carrier element, or a recessed section can be formed on the carrier element before the coating is applied. This reduces the degree of deformation of the coating during forging, thereby preventing, for example, wrinkling of the forged coating. Examples

[0091] A tooth 220 was manufactured using a process similar to that described in the second embodiment, and the resulting tooth was subjected to a test to examine the structure of the coating and the like (Example). For comparison, a tooth was manufactured using a similar process, but the step for forming the coating (step S20) was omitted, and a coating was formed by weld overlay after heat treatment. The resulting tooth was subjected to a similar test (Comparative Example). The dies used for hot forging had the same shape in both the Example and the Comparative Example.

[0092] Fig. Figure 34 is a photograph showing a cross-section of tooth 220 of the example. The marginal section 229 of the coating, the exposed area 225B, and the surface 227A of the coating 227 are as described with reference to Fig. Figure 34 shows that the components are flush with each other and form a forged surface. This confirms that the tooth 220 in the second embodiment can be manufactured using the manufacturing process in the second embodiment. No cracking is observed between the coating 227 and the substrate material 225. No problems occur during the hot forging process carried out after the coating has formed.

[0093] Fig. Figure 35 is an optical micrograph obtained by imaging a surface of the coating of the example and its surroundings. Fig. Figure 36 is an optical micrograph obtained by imaging a surface of the coating of the comparison example and its surroundings. In the case of the coating of the comparison example, which was formed by weld overlay and subsequently not machined by forging, the following are available, as shown in Fig. Figure 36 shows that hard particles 91 are significantly separated from the surface 90A of the coating. In the coating of the example, which was formed and subsequently machined by forging, hard particles 91 located in the surface area are, as shown with reference to Fig. The particles 91, as shown in Figure 35, are embedded in the coating (matrix 95) and arranged side by side. The hard particles 91 are aligned in contact with the surface 90A of the coating. A hard particle 91 that has an area exposed at the surface 90A of the coating 90 has an acute central angle θ (of less than 90°) corresponding to the exposed area. This is presumably due to the fact that during the forging process, the hard particles 91 that protruded from the surface 90A of the coating are pressed into the matrix 95, which has relatively low hardness.

[0094] Fig. Figure 37 is an optical micrograph obtained by imaging an interface between the coating and the substrate of the example, as well as its surroundings. Fig. Figure 38 is an optical micrograph obtained by imaging an interface between the coating and the substrate of the comparison example, as well as its surroundings. In the comparison example, where the coating was formed by weld overlay and subsequently not machined by forging, as shown in Fig. Figure 38 shows that the interface between the coating (matrix 95) and the substrate 100 is flat. In the example, which was machined by forging after the coating was formed, the area encompassing the interface between the coating (matrix 95) and the substrate 100 is flat, as shown in Figure 38. Fig.Figure 37 shows projections 99 formed with the coating (matrix 95) that project onto the substrate material 100. A portion of a corresponding hard particle 91 is incorporated into each projection 99. It is assumed that the projections 99 were formed due to the presence of the hard particles 91 near the interface with the substrate while the coating was being processed by forging. A hard particle 91 that contributed to the formation of a projection 99 has at least one portion incorporated into the projection 99.

[0095] Although the drive wheel and bushings, as components of the crawler track undercarriage, the excavator teeth for a hydraulic excavator, and the teeth for a crusher in the embodiments described above have been described as examples of the machine components of the present invention, the machine components of the present invention are not limited to these. The present invention can be used for a wide range of machine components on which a coating is formed comprising hard particles dispersed in a matrix. Industrial applications

[0096] The machine component and the method for manufacturing it according to the present invention can be used particularly advantageously in a machine component where improved wear resistance is desired, and in the method for manufacturing it. Description of reference symbols

[0097] 1: Crawler track drive device; 2: Crawler track; 3: Crawler track frame; 4: Deflection wheel; 5: Drive wheel; 6: Track plate; 7: Outer link; 8: Inner link; 9: Crawler track link; 10: Running roller; 11: Bearing roller; 12: Connecting bolt; 13: Bushing; 15: Through hole; 50: Carrier material; 51: Projection; 52: Coating; 53: Outer circumferential surface; 59: Burr; 69: Carrier element; 61A: Side surface; 61B: End surface; 62: Bead; 63: Coating; 64: Carrier element; 64A: Outer circumferential surface; 64B: End surface; 70: Welding torch; 71: Welding nozzle; 72: Contact tip; 73: Welding wire; 74: Arc; 80: Nozzle for feeding hard particles; 90: Coating; 90A: Surface; 90B: Surface area of ​​the coating; 91: Hard particle; 92: Melt bath; 95: Matrix; 99: Projection; 100: Support material; 131: Outer circumferential surface; 132: Coating; 133: Inner circumferential surface; 134: Support material; 139: Smaller diameter section; 201: Spoon; 210: Main body; 212: Circumference of the opening; 220: Tooth;221: front end; 222: rear end; 225: carrier material; 225A: covered area; 225B: exposed area; 227: coating; 227A: surface; 229: coating edge section; 230: application section; 250: carrier element; 251: side face; 251A: covered area; 252: one end face; 252A: first chamfered section; 253: other end face; 253A: second chamfered section; 259: coating edge section; 260: coating; 301: breaker; 310: main frame; 320: fixed section; 321: outer tooth of the fixed section; 321A: front end face; 321B: first side face; 321C: third side face; 321D: rear end face; 321E: second side face; 322: crusher plate; 323: recess; 325: carrier material; 327: coating; 330: moving section; 331: outer tooth of the moving section; 333: inner tooth of the moving section; 350: support element; 350A: first end face; 350B: first chamfered section;350C: second chamfered section; 350D: second end face; 350F: side face; 350G: projecting exposed area; 360: coating; and 362: bead;

Claims

[1] Machine component that includes: a substrate material (100) consisting of a first metal; and a coating (90) arranged in contact with the substrate material (100) and covering at least part of a surface of the substrate material (100), the coating (90) comprising: a matrix (95) consisting of a second metal; and hard particles (91) dispersed in the matrix (95); wherein: in a region including an interface between the coating (90) and the carrier material (100), the coating (90) contains a projection (99) projecting toward the carrier material (100); and a part of a hard particle (91) is accommodated in the projection (99), the hard particle (91) is not in contact with the carrier material (100), the center of the hard particle (91) is located outside the projection (99) and the projection (99) has a depth which is smaller than the radius of the hard particle (91). [2] Machine component according to claim 1, which is used as a component (5, 13) of a crawler track undercarriage, as an excavator tooth (220) or as a tooth (321) of a crusher (301).

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