Sliding member and method of manufacturing sliding member

Abstract

A sliding member is provided with a cylindrical metal substrate, a porous layer formed on the inner peripheral surface of the metal substrate without a seam, and a sliding layer covering the porous layer, the porous layer being formed from a metal element or an alloy composition, and the sliding layer being formed from a resin composition.

Description

Technical Field

[0001] The present disclosure relates to sliding members and methods of manufacturing sliding members. Background Art

[0002] Currently, from the perspectives of energy efficiency and CO2 emissions, there is a growing trend toward replacing conventional engine-powered vehicles with battery- and motor-powered electric vehicles (EVs). The output of an electric motor depends on its speed and torque. Increasing the speed suppresses torque and reduces size, so higher motor speeds are essential for miniaturization and weight reduction of components and power savings. Furthermore, for car air conditioners that support vehicle comfort, there is a growing demand for smaller and lighter electric compressors with integrated drive motors.

[0003] The Automotive Transmission Technology Research Institute (TRAMI), a group of Japanese automakers, has announced that it will shift its research focus from internal combustion engines to electric vehicle (EV) motors and related technologies. While the current mainstream speed of EV motors is around 13,000 rpm, there are predictions that this will reach over 20,000 rpm in the near future, leading to research focused on ultra-high speeds of 30,000 to 50,000 rpm. In particular, high speeds are required to achieve both compactness and weight reduction while also achieving high output in EV drive motors and electric compressors.

[0004] In rotating machinery that supports the main shafts of motors, compressors, and other components, such as bearings and seals, that support the rotating bodies play a crucial role. Over time, the sliding surfaces of these mechanical components degrade, increasing their friction coefficients and causing wear. This heat generation causes temperatures to rise, and various parts of the rotating machinery begin to degrade, ultimately failing to meet their mechanical functions and reaching the end of their lifespan. Furthermore, if the friction and heat generated by the high speed of the motor cause oil to leak from the gaps between the bearings supporting the rotating shaft, or if foreign matter is introduced into the gaps, the temperature and vibration of the sliding surfaces become abnormally high, melting the sliding material and causing seizure. Thus, friction and wear are often the primary causes of performance degradation and failure of mechanical components. In particular, the lubrication of sliding bearings used in compressors utilizes sealed refrigerant and refrigeration oil, but the lubrication conditions vary significantly depending on the compressor's operating conditions, with severe lubrication conditions conceivable, such as those with only liquefied refrigerant or those that are nearly dry.

[0005] Therefore, in boundary lubrication environments where oil film formation is difficult due to factors such as high drive system speeds and shaft eccentricity, sliding bearings with excellent wear and seizure resistance are required. Furthermore, bearing dimensional accuracy, such as the clearance between the shaft and the bearing, the shape of the bearing inner diameter surface in contact with the shaft, and the presence of protrusions at the joint (joint), significantly impacts the life of the machine, thus requiring high assembly precision for sliding bearings.

[0006] Furthermore, with regard to sliding bearings used in compressors, the operating environment around the bearings has become stricter due to the switch to new refrigerants accompanying CFC regulations and global warming countermeasures, and higher performance bearings are being demanded.

[0007] Japanese Patent Application Publication No. 2018-179049 proposes the use of rolling bearings in parts requiring high rotational speeds, such as automotive parts. However, rolling bearings have a shorter lifespan than sliding bearings, and therefore, there is a desire for sliding bearings with a longer lifespan that can be used even at high rotational speeds. Summary of the Invention

[0008] It is desirable to provide a sliding member having excellent wear resistance and seizure resistance in a high rotation speed range, and a method for producing the sliding member.

[0009] A sliding member according to one embodiment includes

[0010] Cylindrical metal substrate,

[0011] A seamless porous layer formed on the inner peripheral surface of the metal substrate, and

[0012] a sliding layer covering the porous layer,

[0013] The porous layer is formed of a metal element or an alloy composition,

[0014] The sliding layer is formed of a resin composition.

[0015] A bearing according to one embodiment includes

[0016] Cylindrical metal substrate,

[0017] A porous layer formed on the inner peripheral surface of the metal substrate, and

[0018] a sliding layer covering the porous layer,

[0019] The porous layer is formed of a metal element or an alloy composition,

[0020] The sliding layer is formed of a resin composition.

[0021] A method for manufacturing a sliding member according to one embodiment is a method for manufacturing a sliding member having no joints on a sliding surface, comprising:

[0022] The step of disposing a cylindrical or cylindrical jig inside a cylindrical metal substrate and filling a gap between the inner peripheral surface of the metal substrate and the outer peripheral surface of the jig with raw material powder for the porous layer;

[0023] a step of sintering the raw material powder to form a seamless porous layer composed of a metal element or an alloy composition on the inner peripheral surface of the metal substrate;

[0024] a step of impregnating the surface of the porous layer with a raw material resin of the sliding layer; and

[0025] A step of baking the raw resin to form a sliding layer comprising a resin composition covering the porous layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] [ Figure 1 ] Figure 1 It is a perspective view showing a schematic configuration of a sliding member according to one embodiment.

[0027] [ Figure 2 ] Figure 2 This is a photographic image showing the appearance of a sliding member according to one embodiment.

[0028] [ Figure 3 ] Figure 3 This is a backscattered electron composition image of a cross-sectional structure of a sliding member according to one embodiment.

[0029] [ Figure 4 ] Figure 4 This is a flowchart showing an example of a method for manufacturing a sliding member according to one embodiment.

[0030] [ Figure 5 ] Figure 5 It is a diagram for explaining the filling process of raw material powder.

[0031] [ Figure 6A ] Figure 6A It is a diagram for explaining the shape of a jig used in the raw material powder filling step.

[0032] [ Figure 6B ] Figure 6B This is a diagram for explaining the step of filling raw material powder when the metal substrate has joints.

[0033] [ Figure 7 ] Figure 7 It is a diagram for explaining the impregnation process of the raw material resin.

[0034] [ Figure 8 ] Figure 8 This is a diagram for explaining the polishing process.

[0035] [ Figure 9 ] Figure 9 It is a figure for demonstrating the manufacturing method as a comparative example.

[0036] [ Figure 10 ] Figure 10 It is a diagram for explaining a manufacturing method as another example for comparison.

[0037] [ Figure 11 ] Figure 11 This is a diagram showing a schematic configuration of a high-speed wear testing machine.

[0038] [ Figure 12 ] Figure 12 This is a table summarizing the compositions and the like of sliding members according to Examples 1 to 4 and Comparative Examples.

[0039] [ Figure 13 ] Figure 13 This is a graph showing changes in the amount of wear relative to the shaft rotation speed, measured in a high rotation speed wear test, for sliding members according to Examples 1 and 5 and Comparative Example.

[0040] [ Figure 14 ] Figure 14 This is a graph showing changes in the bearing back surface temperature increase rate relative to the shaft rotation speed measured in a high rotation speed wear test for sliding members according to Example 1 and Comparative Example.

[0041] [ Figure 15 ] Figure 15 This is a graph showing the temporal changes in the back surface temperature of the sliding members according to Example 1 and the comparative example, measured in a high rotation speed wear test.

[0042] [ Figure 16 ] Figure 16 This is a graph showing temporal changes in power consumption measured in a high-speed wear test for sliding members according to Examples 1 and 5 and the comparative example.

[0043] [ Figure 17 ] Figure 17 This is a graph showing changes in the amount of wear relative to the shaft rotation speed, measured in a high rotation speed wear test, for the sliding members according to Examples 1 and 2.

[0044] [ Figure 18 ] Figure 18 This is a graph showing changes in the bearing back surface temperature increase rate relative to the shaft rotation speed measured in a high rotation speed wear test for the sliding members according to Examples 1 and 2.

[0045] [ Figure 19 ] Figure 19This is a graph showing changes in the amount of wear relative to the shaft rotation speed, measured in a high rotation speed wear test, for the sliding members according to Examples 3 and 4.

[0046] [ Figure 20 ] Figure 20 This is a graph showing changes in the bearing back surface temperature increase rate relative to the shaft rotation speed measured in a high rotation speed wear test for the sliding members according to Examples 3 and 4.

[0047] [ Figure 21 ] Figure 21 It is a graph showing the inner diameter roundness of the sliding members according to Example 1 and Example 2.

[0048] [ Figure 22 ] Figure 22 It is a graph showing the inner diameter roundness of the sliding members according to Example 3 and Example 4. DETAILED DESCRIPTION

[0049] A sliding member according to a first aspect of the embodiment includes:

[0050] Cylindrical metal substrate,

[0051] A seamless porous layer formed on the inner peripheral surface of the metal substrate, and

[0052] a sliding layer covering the porous layer,

[0053] The porous layer is formed of a metal element or an alloy composition,

[0054] The sliding layer is formed of a resin composition.

[0055] This approach eliminates seams in the porous layer, and consequently, in the sliding layer covering it. This reduces friction at the seams and reduces heat generation due to friction. This improves wear resistance and seizure resistance in high-speed ranges, and also enhances bearing performance.

[0056] Furthermore, since the porous layer lacks joints, the sliding layer covering it also lacks joints, reducing the torque generated by friction at the joints. This helps reduce power consumption and energy losses, thus contributing to carbon neutrality.

[0057] Furthermore, bearings used in high-speed environments such as EV motors and electric compressors can be replaced with the sliding member according to this embodiment from conventional rolling bearings, thereby achieving size reduction and weight reduction.

[0058] Furthermore, when conventional sliding components with joints in the sliding surface are applied to motors and compressors, an inner diameter cutting process (i.e., matching the inner surface at the joint) is required. However, in the sliding component according to this embodiment, since there are no joints in the porous layer, there are no joints in the sliding layer covering the porous layer, which can eliminate the inner diameter cutting process. Furthermore, by eliminating this process, the generation of industrial waste (carbon contained in the resin composition) generated during cutting can be suppressed, thereby contributing to carbon neutrality.

[0059] A sliding member according to a second aspect of the embodiment is the sliding member according to the first aspect, wherein the sliding layer has an inner diameter roundness of 50 μm or less.

[0060] According to this aspect, the friction at the inner peripheral surface of the sliding layer is further reduced, and thus it is possible to further reduce wear and heat generation.

[0061] A sliding member according to a third aspect of the embodiment is the sliding member according to the first or second aspect, wherein hard particle powder including a Laves phase composed of Co, Mo, and Si is dispersed in the sliding layer.

[0062] The sliding member according to a fourth aspect of the embodiment is the sliding member according to the third aspect, wherein at least one of MoS 2 powder and bronze powder not containing a Laves phase is further dispersed in the sliding layer.

[0063] A sliding member according to a fifth aspect of the embodiment is the sliding member according to the first or second aspect, wherein the resin composition comprises copper sulfide, a thermoplastic resin, molybdenum disulfide, graphite, aramid fiber, and a fluororesin as the balance, and contains greater than 3% by mass and less than 40% by mass of the copper sulfide, 0% by mass or more and less than 4% by mass of the thermoplastic resin, 0% by mass or more and 36% by mass or less of the molybdenum disulfide, 0% by mass or more and less than 10% by mass of the graphite, and 0% by mass or more and less than 10% by mass of the aramid fiber, with the balance being the fluororesin.

[0064] A sliding member according to a sixth aspect of the embodiment is the sliding member according to any one of the first to fifth aspects, wherein:

[0065] The porous layer has:

[0066] a matrix phase comprising Cu and Sn, and

[0067] Hard particles are dispersed in the matrix phase and include a Laves phase composed of Co, Mo, and Si.

[0068] A sliding member according to a seventh aspect of the embodiment is the sliding member according to the sixth aspect, wherein

[0069] The porous layer also has a compound phase dispersed in the matrix phase and containing Co, Fe, Ni, Si, and Cr.

[0070] A sliding member according to an eighth aspect of the embodiment is the sliding member according to any one of the first to seventh aspects, wherein a ratio of a thickness of the porous layer to a thickness of the sliding layer is 6:4 to 8:2.

[0071] A sliding member according to a ninth aspect of the embodiment is the sliding member according to any one of the first to eighth aspects, wherein the metal base material also has no joints.

[0072] A sliding member according to a tenth aspect of the embodiment is the sliding member according to any one of the first to eighth aspects, wherein the metal base material has a joint.

[0073] According to this aspect, the manufacturing cost can be reduced compared to the case of using a metal base material without joints.

[0074] A bearing according to an eleventh aspect of the embodiment includes:

[0075] Cylindrical metal substrate,

[0076] A porous layer formed on the inner peripheral surface of the metal substrate, and

[0077] a sliding layer covering the porous layer,

[0078] The porous layer is formed of a metal element or an alloy composition,

[0079] The sliding layer is formed of a resin composition.

[0080] A method for manufacturing a sliding member according to a twelfth aspect of the embodiment is a method for manufacturing a sliding member having no joints on a sliding surface, comprising:

[0081] The step of disposing a cylindrical or cylindrical jig inside a cylindrical metal substrate and filling a gap between the inner peripheral surface of the metal substrate and the outer peripheral surface of the jig with raw material powder for the porous layer;

[0082] a step of sintering the raw material powder to form a seamless porous layer composed of a metal element or an alloy composition on the inner peripheral surface of the metal substrate;

[0083] a step of impregnating the surface of the porous layer with a raw material resin of the sliding layer; and

[0084] A step of baking the raw resin to form a sliding layer comprising a resin composition covering the porous layer.

[0085] The method involved in the 13th embodiment is the method involved in the 12th embodiment, which further includes a step of pressing a cylindrical core rod into the inner side of the sliding layer while constraining the outer peripheral surface of the metal substrate with a mold, thereby polishing (burnishing) the inner peripheral surface of the sliding layer so that the inner diameter roundness is less than 50 μm.

[0086] The method involved in the 14th embodiment is the method involved in the 12th or 13th embodiment, wherein, in the process of filling the raw material powder, the raw material powder is filled into the gap while rotating the clamp and / or while applying ultrasonic vibration to the clamp.

[0087] The method according to the fifteenth embodiment is the method according to any one of the twelfth to fourteenth embodiments, wherein, in the step of sintering the raw material powder, the metal substrate is placed in a heating furnace together with the jig to sinter the raw material powder.

[0088] Hereinafter, the specific examples of the embodiments will be described in detail with reference to the accompanying drawings. It should be noted that, in this specification, unless otherwise specified, the "%" related to the composition refers to "mass %". In addition, in this specification, unless otherwise specified, "○○~△△" (○○, △△ are both numbers) refers to "above ○○ and below △△". In addition, in this specification, "main component" refers to a component that is 50% by mass or more relative to the overall content of the composition. In addition, in this specification, "hard particle powder" refers to the powder in the mixed powder before sintering or the powder dispersed in the resin composition of the sliding layer, and "hard particles" refer to the particles in the porous layer after sintering. As described later, the Cu and Sn contained in the hard particle powder move to a certain extent into the matrix phase during sintering. Therefore, the content of the hard particles in the porous layer changes from the amount of the hard particle powder in the mixed powder, and the content of each constituent element in the hard particles is different from the content of each constituent element in the hard particle powder (the hard particles are particles of a composition in which the content of Sn and Cu in the chemical composition is reduced to a certain extent compared to the hard particle powder).

[0089] <Sliding member configuration>

[0090] Figure 1 1 is a perspective view showing a schematic configuration of a sliding member 10 according to one embodiment. Figure 2 is a photographic image showing the appearance of the sliding member 10, Figure 3 This is a backscattered electron composition image of the cross-sectional structure of the sliding member 10 . Figure 3In FIG, the upper side of the paper corresponds to the inner peripheral side of the sliding member 10 , and the lower side of the paper corresponds to the outer peripheral side of the sliding member 10 .

[0091] like Figures 1 to 3 As shown, the sliding component 10 is, for example, a sliding bearing, comprising a cylindrical metal substrate 11, a seamless porous layer 12 formed of a metal element or an alloy composition formed on the inner peripheral surface of the metal substrate 11, and a sliding layer 13 formed of a resin composition covering the porous layer 12.

[0092] like Figure 1 As shown, a sliding member 10 serving as a sliding bearing supports a shaft 20, serving as a sliding object, via a sliding layer 13 having a cylindrical inner circumference. The inner diameter roundness of sliding layer 13 can be 50 μm or less, or 20 μm or less. In this case, friction on the inner circumference of sliding layer 13 is reduced, further reducing wear and heat generation.

[0093] The sliding member 10 can be used in either a rotational or linear motion configuration for the shaft 20. For example, the sliding member 10 can be used in sliding parts that utilize oil for linear motion, such as shock absorbers in automobiles. Furthermore, the sliding member 10 can also be used in sliding parts that utilize oil for rotational motion, such as gear pumps that deliver oil through the rotation of a gear-shaped member. The components of the sliding member 10 are described in detail below.

[0094] like Figure 1 and Figure 2 As shown, the metal substrate 11 has a cylindrical shape. As an example, Figure 2 As shown in FIG. 1 , the metal substrate 11 may also be free of seams. The metal substrate 11 having a cylindrical shape without seams is known per se and can be manufactured by conventional methods such as lathe processing. As another example, Figure 6B As shown, the metal substrate 11 may also have a seam that is disconnected in the circumferential direction. In this case, the manufacturing cost of the sliding member 10 can be reduced compared to the case of using a metal substrate 11 without a seam. The cylindrical metal substrate 11 with a seam can be manufactured, for example, by winding a metal sheet into a ring shape. The material of the metal substrate 11 is not particularly limited as long as it has the strength and shape stability to the extent that it can be used as a backing metal base material of a bearing. For example, it can be low carbon steel (SPCC, SS400, etc.) or a copper-plated steel plate in which Cu is plated on an Fe-based plate.

[0095] The porous layer 12 has a seamless cylindrical shape and is formed by sintering metal powder (a mixed powder described later, or an alloy powder formed by alloying the mixed powder during spraying) on ​​the surface of the metal substrate 11. The thickness of the porous layer 12 can be such that at least two metal powders can overlap and sinter, for example, 0.5 mm or less.

[0096] The sliding layer 13 is formed by impregnating the porous layer 12 with a resin composition to a predetermined thickness and then firing the resin composition impregnated into the porous layer 12. Since there are no seams in the porous layer 12, the sliding layer 13 covering the porous layer 12 also does not have seams. The thickness of the sliding layer 13 (the thickness from the surface of the metal substrate 11) can be set to be thicker than the thickness of the porous layer 12 on average, so that the porous layer 12 is not exposed. The ratio of the thickness of the porous layer 12 to the thickness of the sliding layer 13 can be 6:4 to 8:2, for example, 7:3.

[0097] The resin composition of the sliding layer 13 contains a fluororesin as a main component. Examples of the fluororesin serving as the matrix resin of the resin composition include PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxyalkane), FEP (perfluoroethylene propylene copolymer), and EFFE (ethylene tetrafluoroethylene copolymer).

[0098] The resin composition may contain PTFE as a main component of the fluororesin and may contain other fluororesins such as PFA in addition to PTFE as optional additives. The content of the other fluororesins contained as optional components in the resin composition may be 0% by volume or more and 20% by volume or less.

[0099] Commercially available products of PTFE resin include Polyflon (registered trademark) D-210C and F-201 (manufactured by Daikin Industries, Ltd.), Fluon (registered trademark) AD911D (manufactured by Asahi Glass Co., Ltd.), and Teflon (registered trademark) 31JR and 6C-J (manufactured by Mitsui & DuPont Fluorochemicals).

[0100] like Figure 3As shown, the resin composition of the sliding layer 13 may contain dispersed hard particle powder 13a containing a Laves phase composed of Co, Mo, and Si. The Laves phase is an AB2-type intermetallic compound composed of an A element and a B element with an atomic radius ratio of approximately 1.2:1. There are three types of structures: MgZn2 (C14), MgCu2 (C15), and MgNi2 (C36). The Laves phase composed of Co, Mo, and Si (more specifically, Co3Mo2Si) is a Laves phase with Mo as the A element, Co as the B element, and Si replacing 25 atomic percent of the Co. This Laves phase is a hexagonal MgZn2-type Laves phase. The Vickers hardness of the Co3Mo2Si Laves phase is Hv 1000-1200. It is believed that the hard particle powder 13a dispersed in the sliding layer 13 is subjected to a higher load than the resin composition forming the sliding layer 13, but the load is supported by the precipitation of a hard Laves phase composed of Co, Mo and Si on the friction surface, which can advantageously reduce the wear of the sliding layer 13.

[0101] Furthermore, the Mo in the Laves phase and the S in the lubricating oil form a sulfide film of MoS2 on the friction surface. MoS2 is a sulfide known as a solid lubricant alternative to lead, contributing to improved friction properties. Since the bonds between sulfur are weaker than those between molybdenum and molybdenum and sulfur, the bonds between sulfur are selectively severed during friction, resulting in lubrication and effectively suppressing wear. Furthermore, the Mo oxides produced on the friction surface by oxidation of the Mo in the Laves phase during sliding also exert a lubricating effect, effectively suppressing wear.

[0102] At least one of molybdenum disulfide (MoS2) powder and bronze powder free of Laves phase may be further dispersed in the resin composition of the sliding layer 13. As described above, MoS2 is a sulfide known as a solid lubricant alternative to lead, contributing to improved friction properties. Since the bonds between sulfurs are weaker than those between molybdenum and between molybdenum and sulfur, the bonds between sulfurs are selectively severed during friction, resulting in lubrication and effectively suppressing wear.

[0103] As a modified example, the resin composition of the sliding layer 13 may be composed of copper sulfide (CuS), a thermoplastic resin, molybdenum disulfide (MoS2), graphite, aramid fiber, and a fluororesin as the balance (the resin composition does not contain lithium phosphate). In this case, the resin composition may contain greater than 3% and less than 40% by mass of copper sulfide, 0% and less than 4% by mass of thermoplastic resin, 0% and less than 36% by mass of molybdenum disulfide, 0% and less than 10% by mass of graphite, and 0% and less than 10% by mass of aramid fiber, with the balance being fluororesin.

[0104] The inclusion of copper sulfide as a metal sulfide in the resin composition forming the sliding layer 13 improves the heat dissipation characteristics of the sliding layer 5. This suppresses the temperature rise of the sliding layer 5 caused by the sliding of the sliding object and suppresses deformation of the sliding layer 5 associated with the temperature rise.

[0105] Furthermore, the inclusion of copper sulfide in the resin composition forming sliding layer 13 improves the strength of sliding layer 13. It is known that the inclusion of carbon fiber fillers in the resin composition forming the sliding layer improves the strength of the resin layer. In contrast, the inclusion of copper sulfide in the resin composition improves the strength to the same degree as when carbon fiber fillers are included, even without the inclusion of carbon fiber fillers. This increased strength of sliding layer 13 also suppresses deformation of sliding layer 5 caused by sliding of the sliding object.

[0106] If the deformation of the sliding layer 13 increases, the wear increases compared to when the deformation is small. Therefore, by suppressing the deformation of the sliding layer 13, the wear of the sliding layer 13 is suppressed, and the wear resistance is improved. In addition, by increasing the strength of the sliding layer 13, the wear is also suppressed. Furthermore, by suppressing the wear of the sliding layer 13, the exposure of the porous layer 12 can be suppressed. This can prevent the porous layer 12 from directly contacting the sliding surface, which can cause dry contact and other causes of galling, thereby improving galling resistance.

[0107] Known copper sulfides include cuprous sulfide (Cu2S) and copper sulfide (CuS). Cuprous sulfide (Cu2S) is stable even at temperatures above 1000°C. In contrast, copper sulfide (CuS) transforms into cuprous sulfide (Cu2S) at around 200°C. When polytetrafluoroethylene is used as the resin, the resin composition 4 is heated at a temperature exceeding 327°C during the calcination step of the sliding layer 13. Therefore, when the resin composition contains copper sulfide (CuS), the copper sulfide (CuS) transforms into cuprous sulfide (Cu2S) during the calcination step of the sliding layer 13.

[0108] Thus, cuprous sulfide (Cu2S) is contained in the sliding layer 13 of the sliding member 10 as a manufactured product. However, cuprous sulfide (Cu2S) or copper sulfide (CuS) can be used as the raw material of copper sulfide, but copper sulfide (CuS) is preferably used from the perspective of workability.

[0109] By further including molybdenum disulfide as a metal sulfide in the resin composition forming the sliding layer 13, the sliding properties relative to the sliding object that slides in contact with the sliding layer 5 are improved. Furthermore, by including graphite in the resin composition 4, the sliding properties are also improved. This allows a structure that does not contain lead (Pb) to achieve sliding properties comparable to those of a sliding member containing Pb. The following details the resin composition of the sliding layer 13 according to a modified example.

[0110] [Copper sulfide: more than 3% by mass and less than 40% by mass]

[0111] To improve heat dissipation and strength, the resin composition forming the sliding layer 13 preferably contains copper sulfide at a concentration of greater than 8% by mass and less than 40% by mass. If the amount of copper sulfide added is less than 3% by mass and greater than 40% by mass, heat dissipation characteristics deteriorate, impairing wear resistance. Commercially available products include copper sulfide (CuS) manufactured by Terada Yakusen Kogyo Co., Ltd., copper sulfide (CuS) manufactured by Kanto Chemical Co., Ltd., and cuprous sulfide (Cu2S) manufactured by Kojundo Chemical Research Institute Co., Ltd.

[0112] [Plastic resin: 0 mass % or more and 4 mass % or less]

[0113] In the resin composition of the sliding layer 13 according to one modification, the thermoplastic resin is not an essential additive, but when added, it can improve the wear resistance and creep resistance that are disadvantages of fluororesins, and therefore is preferably added.

[0114] When a thermoplastic resin is added, if the content exceeds 4% by mass, the low friction properties of the fluororesin may be impaired. Examples of commercially available thermoplastic PPS resins include PQ-208 manufactured by DIC Corporation and Fortron (registered trademark) KPS manufactured by KUREHA Corporation.

[0115] [Graphite: 0 mass % or more and 10 mass % or less]

[0116] In the resin combination of the sliding layer 13 that a modification relates to, graphite is not an essential additive, but can be expected to contribute to low friction characteristics and wear resistance. In addition, cavitation resistance is excellent, can be expected to prevent the erosion of the resin coating caused by the cavitation under the presence of lubricating oil. When adding graphite, when exceeding 10 mass %, low friction characteristics can be hindered. It should be noted that, as commercially available product, the AT series etc. that UCP, CPB, ORIENTAL Industrial Co., Ltd. that can be enumerated manufacture by Nippon Graphite Industries, Ltd.

[0117] [Molybdenum sulfide: 0 mass % or more and 36 mass % or less]

[0118] In the resin composition of the sliding layer 13 according to one modification, molybdenum disulfide (MoS 2 ) is not an essential additive, but can reduce frictional resistance by adding it.

[0119] When the addition amount of molybdenum disulfide exceeds 36% by mass, the impregnation property in the impregnation step into the porous layer deteriorates. It should be noted that commercially available products include H / GMoS2 manufactured by Taiyo Mining Co., Ltd. and molybdenum disulfide powder series manufactured by Daizo Co., Ltd.

[0120] [Aramid fiber: 0% by mass or more and 10% by mass or less]

[0121] In the resin composition of the sliding layer 13 of one modification, aramid fiber is not an essential additive, but is added to obtain mechanical strength. When aramid fiber is added, if the amount is 10% by mass or more, uniform dispersion is hindered, resulting in reduced wear resistance. It should be noted that commercially available products include Kevlar (registered trademark) manufactured by Toray DuPont and Teijin's Twaron (registered trademark).

[0122] As another modified example, the resin composition of the sliding layer 13 may contain any one or two or more of zinc compounds (ZnS (zinc sulfide), ZnO (zinc oxide), ZnSO4 (zinc sulfate, etc.), carbon fibers, iron oxides, barium sulfate, aramid fibers, graphite, calcium compounds (CaCO3 (calcium carbonate), CaSO4 (calcium sulfate), Ca(OH)2 (calcium hydroxide), etc.), zinc, and zinc alloys as optional additives. By including the zinc compound in the resin composition, deformation of the sliding layer 13 can be suppressed by increasing the elastic modulus, and the increase or decrease in the contact area of ​​the sliding layer 13 due to deformation caused by external force can be suppressed. In addition, by including the zinc compound in the resin composition, the deformation of the sliding layer 13 due to external force can be suppressed. Carbon fibers can improve the value of dynamic friction and the variation between static and dynamic friction, thereby improving sliding properties. The inclusion of iron oxides in the resin composition can improve the elastic modulus in addition to improving wear resistance. The inclusion of barium sulfate or aramid fibers in the resin composition can improve wear resistance without hindering the improvement in elastic modulus achieved by adding a zinc compound. The inclusion of graphite in the resin composition can reduce frictional resistance without hindering the improvement in elastic modulus achieved by adding a zinc compound. The inclusion of calcium compounds, zinc, or zinc alloys in the resin composition can improve wear resistance without hindering the improvement in elastic modulus achieved by adding a zinc compound.

[0123] As a variation, the porous layer 12 may include a matrix phase containing Cu and Sn and hard particles dispersed in the matrix phase. The porous layer 12 may be formed by sintering an alloy powder formed by alloying a mixed powder during spraying. By forming the alloy powder, the sintering of the powder is promoted to form a neck, and the powders can be fully bonded to each other. In addition, by forming the alloy powder, the hard particles are miniaturized and evenly dispersed in the matrix phase. It should be noted that, when the hard particle powder 13a is dispersed in the sliding layer 13, the porous layer 13 may not include hard particles.

[0124] The matrix phase is a bronze-based alloy containing Cu as a main component and further containing Sn. The matrix phase may be composed of a solid solution of Cu, Sn, and Ni.

[0125] Bi particles can be distributed at the grain boundaries of the matrix phase. In this case, when the sliding layer 4 wears away and a portion of the porous layer 3 is exposed, Bi exhibits the same self-lubricating effect as Pb in conventional lead bronze, acting as a lubricant between the two friction surfaces, thereby reducing friction.

[0126] The hard particles may include a Lavers phase composed of a composition of Co, Mo, and Si. When the sliding layer 13 wears away and a portion of the porous layer 12 is exposed, it is believed that the hard particles dispersed in the matrix phase can bear a higher load than the soft bronze that forms the matrix phase. However, the hard Lavers phase composed of a composition of Co, Mo, and Si precipitates on the friction surface and supports the load, which can advantageously reduce the wear of the porous layer 12. In addition, the Mo in the Lavers phase and the S in the lubricating oil can form a sulfide film of MoS2 on the friction surface. MoS2 is a material known as a sulfide that helps improve friction properties as a solid lubricant instead of lead. Compared to the combination between molybdenum and molybdenum and sulfur, the combination between sulfur is weaker. Therefore, when friction occurs, the combination between sulfur is selectively cut off, thereby generating lubrication, which can effectively suppress wear. In addition, the Mo oxide produced on the friction surface by oxidation of the Mo in the Lavers phase during sliding can also play a lubricating effect and effectively suppress wear.

[0127] When the porous layer 12 contains hard particles, when the porous layer 12 is set to 100% by mass as a whole, the content of hard particles can be, for example, 40% by mass or less. When the porous layer 12 is set to 100% by mass as a whole, the content of hard particles can be, for example, 0.1% by mass or more. If the content of hard particles is 0.1% by mass or more, the effect of reducing the wear of the porous layer 12 as described above can be obtained. In addition, when the porous layer 12 is set to 100% by mass as a whole, the content of the Laves phase composed of Co, Mo and Si can be, for example, 0.1 to 20% by mass. When the hard particle powder 13a is dispersed in the sliding layer 13 and the porous layer 12 does not contain hard particles, when the porous layer 12 is set to 100% by mass as a whole, the total content of Cu and Sn can be 99.9% or more.

[0128] The porous layer 3 may also include a compound phase dispersed in a matrix phase. The compound phase may include Co, Fe, Ni, Si, and Cr. By forming the compound phase in the matrix phase, the hardness of the matrix phase can be increased, which can advantageously contribute to improving seizure resistance.

[0129] The sliding member 10 according to the present embodiment includes four types of sliding members: (1) a configuration in which hard particles are contained in the porous layer 12 but no hard particle powder 13a is contained in the sliding layer 13; (2) a configuration in which no hard particles are contained in the porous layer 12 but the hard particle powder 13a is contained in the sliding layer 13; (3) a configuration in which hard particles are contained in the porous layer 12 and the hard particle powder 13a is contained in the sliding layer 13; and (4) a configuration in which no hard particles are contained in the porous layer 12 and no hard particle powder 13a is contained in the sliding layer 13. In any of the configurations (1) to (3), when the total of the porous layer 12 and the sliding layer 13 (i.e., the portion obtained by excluding the metal substrate 11 from the entire sliding member 10) is taken as 100% by mass, the total content of the hard particles and the content of the hard particle powder 13a may be 1 to 20% by mass, for example, 15% by mass.

[0130] According to this embodiment, since the porous layer 12 of the sliding member 10 has no joints, the sliding layer 13 covering the porous layer 12 also has no joints. This reduces friction at the joints and reduces heat generation caused by friction. This improves wear resistance and seizure resistance in the high-speed range, and also enhances the performance of the bearing itself.

[0131] Furthermore, according to this embodiment, since the porous layer 12 has no joints, the sliding layer 13 covering the porous layer 12 also has no joints. This reduces the torque generated by friction at the joints. This helps reduce power consumption and energy losses, thus contributing to carbon neutrality.

[0132] Furthermore, bearings used in high-speed environments such as EV motors and electric compressors can be replaced with the sliding member 10 according to this embodiment from conventional rolling bearings, thereby achieving size reduction and weight reduction.

[0133] Furthermore, when conventional sliding components with joints on the sliding surface are applied to motors and compressors, an inner diameter cutting process (i.e., matching the inner surface at the joint) is required. However, the sliding component 10 according to this embodiment has no joints in the porous layer 12, and thus no joints are formed in the sliding layer 13 covering the porous layer 12, thereby eliminating the inner diameter cutting process. Furthermore, by eliminating this process, the generation of industrial waste (carbon contained in the resin composition) generated during cutting can be suppressed, thereby contributing to carbon neutrality.

[0134] <Method for Manufacturing Sliding Member>

[0135] Next, refer to Figure 4 , a method for manufacturing the sliding member 10 will be described. Figure 4 1 is a flowchart showing an example of a method for manufacturing the sliding member 10 . Figure 5 This is a diagram for explaining the filling process of raw material powder. Figure 6A This is a diagram for explaining the shape of a jig 31 used in the raw material powder filling step.

[0136] like Figures 4 to 6A As shown, first, a cylindrical or columnar jig 31 is placed inside a cylindrical metal substrate 11, and the raw material powder of the porous layer 12 is filled into the gap between the inner peripheral surface of the metal substrate 11 and the outer peripheral surface of the jig 31 (step S10).

[0137] exist Figure 6A In the example shown, the jig 31 includes a cylindrical or columnar main body 31a and a step 31b provided at an axial end of the main body. Alternatively, a radially outwardly projecting step 31c may be provided at the end of the main body 31a on the side of the step 31b. In this case, when the main body 31a of the jig 31 is positioned inside the metal substrate 11, the top of the step 31a abuts the inner circumferential surface of the metal substrate 11, making it easier to coaxially position the metal substrate 11 with the main body 31a of the jig 31.

[0138] Figure 6B 1 is a diagram for explaining the filling process of raw material powder when the metal substrate 11 has a joint. Figure 6B As shown, when the metal substrate 11 has a seam, the metal substrate 11 is first pressed into the inner side of the cylindrical shell 34, thereby making the seam (joint) close. Next, the clamp 31 is coaxially arranged inside the metal substrate 11 pressed into the shell 34, and the raw material powder of the porous layer 12 is filled into the annular gap between the inner circumference of the metal substrate 11 and the outer circumference of the clamp 31. By filling the raw material powder into the annular gap while the seam (joint) of the metal substrate 11 is closed, no seam such as height difference is generated on the inner circumference of the sintered porous layer 12.

[0139] like Figure 5 and Figure 6A As shown, a rotating shaft 32 may be connected to the table 31b of the jig 31, and while the jig 31 is rotated by a motor connected to the rotating shaft 32, raw material powder is sprinkled from above the jig 31, so that the raw material powder of the porous layer 12 falls and fills the gap between the inner peripheral surface of the metal substrate 11 and the outer peripheral surface of the jig 31. In this way, the fluidity of the raw material powder filled in the gap can be improved, and the filling density can be increased.

[0140] like Figure 5As shown, an excitation terminal of an ultrasonic transmitter can be connected to the workpiece 33 supporting the jig 31. While ultrasonic vibrations are being applied to the jig 31 via the workpiece 33, raw material powder can be sprinkled from above the jig 31, causing the raw material powder of the porous layer 12 to fall and fill the gap between the inner circumferential surface of the metal substrate 11 and the outer circumferential surface of the jig 31. This can also improve the fluidity of the raw material powder filling the gap, thereby increasing the filling density.

[0141] The raw material powder can be a first powder containing Cu and Sn, a mixed powder obtained by mixing the first powder with a hard particle powder containing a Laves phase composed of Co, Mo and Si, or a mixed powder obtained by mixing the first powder and the hard particle powder with a second powder containing Cu, Co, Fe, Ni, Si and Cr.

[0142] Here, the first powder is a bronze alloy powder containing Cu as a main component and further containing Sn. The first powder may also contain Bi or P. When the first powder contains Bi, Bi particles precipitate in the matrix phase 10 during the sintering of the raw material powder described later (i.e., step S11), and Bi exhibits the same self-lubricating effect as Pb in conventional lead bronze, thereby achieving low friction. In addition, when the first powder contains P, oxygen mixed in the copper can be removed (deoxidation) to suppress hydrogen embrittlement. The content of each constituent element of the first powder can be Sn: 10-11% by mass, Cu: the balance. When Bi is also contained, Bi: 7-9% by mass is preferred, and when P is contained, P: 0.02% by mass or less is preferred. The amount of the first powder in the raw material powder is the balance obtained by subtracting the total amount of powders other than the first powder from the total amount of the raw material powder.

[0143] The hard particle powder is an alloy powder containing a Laves phase composed of Co, Mo and Si and Cu, and is a hard particle powder containing Cu, Si, Fe, Mo, Co and Cr. The hard particle powder may further contain Sn, for example, more than 1% by mass of Sn. The solidus temperature of the hard particle powder without Sn reaches close to 1450°C, but by containing Sn, the solidus temperature of the hard particle powder can be lowered, and the hard particle powder can be solid-phase sintered to the backing metal matrix at around 800°C. In addition, the Sn contained in the hard particle powder dissolves and diffuses into the Cu-Sn matrix phase side generated by the first powder during sintering. Sintering is carried out by shrinking the Sn powder, thereby showing solid solution strengthening brought about by the Sn in the matrix phase and the Sn contained in the hard particle powder. When the total mass of the hard particle powder is taken as 100 mass%, the content of each constituent element in the hard particle powder can be Co: 14-20 mass%, Mo: 24-28 mass%, Si: 3-7 mass%, Fe: 2-16 mass%, Cr: 1-10 mass%, and Cu: the balance. When Sn is included, when the total mass of the hard particle powder is taken as 100 mass%, the content of each constituent element in the hard particle powder can be Co: 14-20 mass%, Mo: 24-28 mass%, Si: 3-7 mass%, Fe: 2-16 mass%, Cr: 1-10 mass%, Sn: 1-15 mass%, and Cu: the balance. When the total mass of the raw material powder is taken as 100 mass% (i.e., when the total mass of the sliding layer 12 is taken as 100 mass%), the amount of hard particle powder added can be 1-40 mass%, preferably 1-3 mass%. Since Cu and Sn are dissolved from the hard particle powder during sintering, the content of the hard particles in the sliding layer 12 varies depending on the blending amount of the hard particle powder in the raw material powder.

[0144] The second powder is an alloy powder containing Cu as a main component and further containing Co, Fe, Ni, Si, and Cr. The second powder may also contain Sn, for example, 1% by mass or more of Sn. The solidus temperature of the second powder without Sn reaches approximately 1240°C, but the inclusion of Sn can lower the solidus temperature of the second powder, allowing solid-phase sintering of the second powder onto the backing metal matrix at around 800°C. When Sn is included, the contents of the constituent elements in the second powder, based on 100% by mass of the second powder, can be Co: 0.6-4.6% by mass, Fe: 1.6-5.6% by mass, Ni: 10-14% by mass, Si: 0.5-4.5% by mass, Cr: 0.5-1.5% by mass, Sn: 1-15% by mass, and Cu: the remainder. When the second powder is included in the raw material powder, based on 100% by mass of the raw material powder, the amount of the second powder can be 2-38% by mass, preferably 10-38% by mass, and more preferably 17-19% by mass.

[0145] When the entire raw material powder is taken as 100 mass %, the blending amount of the hard particle powder can be 1 to 40 mass %, and the blending amount of the second powder can be 15 to 18 mass %. In this case, excellent shear workability can be achieved.

[0146] The first powder, hard particle powder, and second powder can be produced by spraying, for example, using a gas atomization method. In the gas atomization method, the heat source for melting can be high frequency, and the crucible (with a nozzle at the bottom) can be made of zirconia.

[0147] The particle size of the first powder can be, for example, 45 μm to 180 μm. The particle size of the hard particle powder can be a fine powder of 53 μm or less. The particle size of the second powder can be 53 μm to 150 μm. Here, "particle size" refers to the particle size distribution measured by the laser diffraction scattering method using the particle size distribution measuring device MT3300EXII manufactured by MicrotracBEL. This measurement method is based on the test procedure after the step of extracting the powder from the paste in "Laser Diffraction Particle Size Distribution Measurement Test 4.2.3" of JIS Z3284-2.

[0148] The alloy powder obtained by alloying the mixed powder by atomization during spraying can be sprinkled from above the jig 31 to fill the gap between the inner peripheral surface of the metal substrate 11 and the outer peripheral surface of the jig 31 .

[0149] Next, the metal substrate 11 is placed in a heating furnace and the raw material powder is sintered at 800-900°C, thereby forming a seamless porous layer 12 composed of a single metal or alloy composition on the inner circumference of the metal substrate 11 (step S20). In step S20, after the fixture 31 is separated from the rotating shaft 32, the metal substrate 11 and the fixture 31 can be placed in the heating furnace together to sinter the raw material powder. When using a metal substrate 11 with a joint, the metal substrate 11, the fixture 31, and the housing 34 can be placed in the heating furnace together to sinter the raw material powder.

[0150] As described above, the solidus temperatures of the hard particle powder and the second powder without Sn reach approximately 1450°C and 1240°C, respectively. However, the inclusion of Sn lowers the solidus temperatures of the hard particle powder and the second powder, allowing them to be solid-phase sintered onto the metal substrate 11 (backing metal matrix) at approximately 800°C. Furthermore, during sintering, the Sn encapsulated within the hard particle powder dissolves and diffuses into the Cu-Sn matrix phase generated by the first powder. Sintering proceeds through Sn powder shrinkage, resulting in solid-solution strengthening due to the Sn in the matrix phase and the Sn encapsulated within the hard particle powder, ultimately forming a high-strength alloy.

[0151] Next, the raw material resin of the sliding layer 13 is impregnated into the surface of the porous layer 12 (step S30). Specifically, for example, Figure 7 As shown, a predetermined amount of resin composition is supplied to the porous layer 12 formed on the inner circumference of the metal substrate 11, and the resin composition is pressed onto the porous layer 12 by the rotational pressure of the impregnation roller, so that the resin composition is impregnated into the porous layer 12. In the resin composition supplied to the porous layer 3, at least one of a hard particle powder 13a comprising a Lavers phase composed of Co, Mo and Si and a molybdenum disulfide (MoS2) powder can be dispersed. As a modified example, the resin composition includes copper sulfide as an additive, may also include molybdenum disulfide, and may also include graphite and aramid fiber as other additives. The amount of the resin composition supplied to the porous layer 12 is the amount of the porous layer 12 that is covered with a thickness that does not expose the porous layer 12 from the surface of the sliding layer 13 after the resin composition is sintered, which will be described later.

[0152] Next, the resin composition is heated at a temperature exceeding the melting point of the resin contained in the resin composition, the resin is melted, and after the organic solvent is volatilized, the resin is solidified to form a sliding layer 13 composed of the resin composition covering the porous layer 12 (step S40). Heating the resin composition at a predetermined temperature to form the sliding layer 13 is called firing. It should be noted that the melting point of polytetrafluoroethylene used as the resin is 327°C. The sliding layer 13 can be fired by heating the resin composition at a temperature exceeding the melting point of polytetrafluoroethylene (e.g., 400-500°C) using a firing furnace.

[0153] Next, refer to Figure 8 By pressing the cylindrical core rod 42 into the inner side of the sliding layer 13 while constraining the outer peripheral surface of the metal substrate 11 by the die 41, the inner peripheral surface of the sliding layer 13 is burnished to make the inner diameter roundness less than 50 μm (step S50). Figures 1 to 3 ).

[0154] It should be noted that as an example for comparing the method of manufacturing the sliding member 10, the following method is considered: Figure 9As shown, a composite blank composed of the porous sintered layer and the resin composition is produced by impregnating the inner circumference of a porous sintered layer formed into a cylindrical shape with a resin composition. The composite blank is then pressed into the inner side of a seamless cylindrical metal substrate, and then heat-treated to bond the composite blank and the metal substrate together. However, in order to impregnate the resin composition into a thin porous sintered layer having a thickness of less than 1 mm, a strong backing metal matrix is ​​required. Without a backing metal matrix, the composite blank composed of the porous sintered layer and the resin composition will immediately break or deform. Therefore, with this method, a composite blank composed of the porous sintered layer and the resin composition cannot be obtained, and therefore, the sliding member 10 having the above-mentioned structure cannot be obtained.

[0155] In addition, as another example for comparing the method of manufacturing the sliding member 10, the following method is also considered: Figure 10 As shown, a bearing plate is produced by sintering a porous layer on one side of a flat metal substrate (backing metal), then sintering a sliding layer (bearing layer) from a resin composition on the porous layer. The bearing plate is then formed into a cylindrical shape by deep drawing, and the ends are cut. However, this method causes cracks in the sliding layer made of the resin composition during deep drawing, causing it to peel off from the porous layer, thus preventing the production of a sliding member 10 having the above-described structure.

[0156] <Example>

[0157] Next, specific examples according to this embodiment will be described.

[0158] (Manufacturing of sliding components)

[0159] First, as Examples 1 to 4, a carbon steel round bar was lathe-machined to an outer diameter of 22 mm, an inner diameter of 20.62 mm, and an overall length of 10.35 mm, yielding a seamless, thin-walled, cylindrical metal substrate 11. Furthermore, as Example 5, a carbon steel plate having a length of 67 mm, a width of 11 mm, and a thickness of 0.75 mm was rolled into a sleeve-like shape to yield a (seam-type) cylindrical metal substrate 11 having a seam width of 2 mm or less. It should be noted that a hollow (tube-like) welded steel pipe, etc., may be used as the carbon steel round bar.

[0160] Next, a powder obtained by removing coarse powder having a particle size of 150 μm or more from bronze powder (amorphous, brand: CP-301) manufactured by Fukuda Metal Foil Powder Co., Ltd. was prepared as raw material powder for the porous layer 12. The chemical composition of the bronze powder was Cu-10Sn.

[0161] Then, regarding Examples 1 to 4, refer to Figure 5 and Figure 6AA carbon steel fixture 31 with an outer diameter of Φ19.96 mm was inserted into a metal substrate 11 with an inner diameter of Φ20.62 mm. Raw material powder was added into the 0.3 mm gap between the inner circumference of the metal substrate 11 and the outer circumference of the fixture 31. Since the inner diameter of the metal substrate 11 is Φ20.6 mm, the outer diameter of the fixture 31 is Φ19.96 mm, and the total length is 10.35 mm, the powder filling volume is 0.21 cm 3 Regarding Example 5, refer to Figure 6B After pressing the metal substrate 11 into the inner side of the housing 34 to close the seam (joint), a carbon steel fixture 31 is coaxially positioned inside the metal substrate 11, which is still pressed into the housing 34. Raw material powder is then introduced into the 0.3 mm annular gap between the inner circumference of the metal substrate 11 and the outer circumference of the fixture 31. In any of Examples 1 to 5, to ensure good fluidity of the powder introduced into the gap, a rotating shaft is connected to the fixture 31, and the fixture is rotated by a motor while the powder is being filled. In this state, sintering is performed in a sintering furnace at a sintering temperature of 880°C and a conveyor speed of 230 mm / min.

[0162] Next, the inside of a cylindrical metal substrate 11 sintered with bronze powder was impregnated with resin. In Examples 1, 2, and 5, the impregnating resin consisted of 2% by volume graphite powder, 15% by volume hard particle powder containing a Laves phase composed of Co, Mo, and Si, and the balance PTFE resin. To enhance self-lubricity, 15% by volume MoS2 powder was added. The chemical composition of the hard particle powder was Cu-4.5Sn-5Si-15Fe-16Co-4Cr-26Mo, with a particle size of less than 53 μm. The graphite powder was manufactured by Nippon Graphite (brand: CPBW-5). In Examples 3 and 4, the impregnating resin consisted of 4.0% by volume graphite, 7.25% by volume MoS2, 10.95% by volume CuS, and the balance PTFE resin.

[0163] As a resin impregnation method, refer to Figure 7 The resin was applied to the inside of a metal substrate 11 with an outer diameter of 22 mm, an inner diameter of 20 mm, and a total length of 10 mm using a doctor blade. While being pressed with a rolling mandrel of 11.7 mm, the rotating pressure of the rolling impregnated the resin into the porous sintered layer 12. The material was then fired in a firing furnace at a temperature of 480°C and a conveyor speed of 1000 mm / min.

[0164] Next, in Examples 1, 3, and 5, referring to Figure 8Using an Amsler testing machine, while using a mold 41 with an inner diameter of Φ14.065mm to constrain the outer peripheral surface of the metal substrate 11, a core rod 42 with an outer diameter of Φ12.160mm is pressed into the inner side of the sliding layer 13, thereby applying a load to the inner peripheral surface of the sliding layer 13 for correction (polishing). Figure 21 : is a diagram showing the inner diameter roundness of the sliding member involved in Example 1 (with polishing) and Example 2 (without polishing). Figure 22 : is a graph showing the inner diameter roundness of the sliding member involved in Example 3 (with polishing) and Example 4 (without polishing). Figure 21 and Figure 22 As shown, it was confirmed that the oval shape disappeared by polishing, and a good roundness of 20 μm or less was ensured.

[0165] As a comparative example, the same bronze powder as in Examples 1 to 5 was sprinkled onto a carbon steel plate (metal substrate) and sintered to form a porous layer. Subsequently, the porous layer was impregnated with the same resin as in Examples 3 and 4 and then sintered to form a sliding layer covering the porous layer. This layer was then rolled. The rolled metal substrate was then formed into a sleeve with the sliding layer facing inward, creating a sliding member in which the metal substrate, porous layer, and sliding layer all had joints (joints).

[0166] Figure 12 This is a table summarizing the compositions and the like of the sliding members according to Examples 1 to 5 and Comparative Example produced by the above-described steps.

[0167] (High speed wear test)

[0168] Next, the performance of the sliding members of Examples 1 to 5 and the comparative example was compared by a high rotation speed wear test. Figure 11 A high-speed wear tester is shown in the figure. This tester measures the temperature of the back of the bearing when the test material is subjected to load and speed through the mating shaft. It is mainly suitable for the evaluation of wear and heat in the high-speed area. An oil bath is set in the test section, and it is designed to be able to perform evaluations in both oil and non-lubricated environments. In addition, in order to achieve high-speed evaluation, the spindle motor (model S262B-SJ03, rated output power 1.2kW, rated voltage 200V, rated current 4.8A) manufactured by Jin Sakura Electric Co., Ltd. is directly connected to the front end of the mating shaft Φ6h7 via a spring chuck. As a result, it is designed to be able to perform evaluations up to 60,000 rpm with an accuracy of less than 0.002mm of shaft runout. The spindle motor is water-cooled via a cooler at a flow rate of 0.7L / min.

[0169] The outer diameter of the mating shaft ranges from 11.957mm to 11.975mm, and the inner diameter of the housing ranges from 14.000mm to 14.018mm. Both are made of SKD-11, with a hardness of HRC58 after full quenching. The bearing backside temperature is measured every second using a data logger, using a thermocouple inserted into a 6mm diameter hole at a position 1.5mm from the bearing backside.

[0170] Next, regarding the test environment, the presence or absence of lubrication of the bearings significantly impacts performance. For example, in air conditioning compression mechanisms such as automotive air conditioning compressors, where the orbiting scroll is pressed firmly against the fixed scroll and undergoes orbiting motion, lubricating oil has difficulty flowing into the bearings. Furthermore, in EV drive motors, high speeds are essential to achieve both compactness and weight reduction while also achieving high output. The bearings supporting the motors utilize oil-lubricated and grease-lubricated bearings, but due to the simplified surrounding structure, oil lubrication of the bearings is virtually impossible. Given these practical constraints, this test was conducted in a non-lubricated environment, measuring frictional heat generation and wear relative to shaft speed. Frictional heat generation was evaluated using the bearing temperature rise rate as an indicator, with regression analysis analyzing the slope of the temperature relative to the time it took for the bearing backside temperature to reach 120°C. Wear was determined by measuring the wall thickness of the sliding member before and after the test using a pipe micrometer and determining the change in wall thickness at the load point.

[0171] The maximum shaft speed for a compressor spindle is 10,000 rpm, while for an EV motor, it reaches approximately 30,000 rpm. Considering this, three speed levels were set: 10,000 rpm, 20,000 rpm, and 30,000 rpm. Considering the operating limits and safety of the spindle motor at high speeds, a radial load of 3 N was applied to the bearing in one direction. The target clearance between the bearing and the shaft was set at 0.1 mm, and the shaft was ground and polished to a surface roughness of Ra 0.17 μm for testing.

[0172] It should be noted that the friction torque caused by the rotational motion can be converted into electric power and thus can be expressed as in the following equation (1).

[0173] E=P=2π·N·T / 60=2π·N·F·R / 60…Equation (1)

[0174] Where R is the rotation radius (m), F is the friction force (N), N is the shaft rotation speed (rpm), T is the torque (N·m), E is the electric power (W), and P is the power (W).

[0175] (Results and Investigation)

[0176] Figure 13The change of the wear amount W with respect to the shaft speed in a non-lubricated environment is shown for the sliding members of Examples 1, 5 and Comparative Example. Figure 14 The change in the bearing back surface temperature increase rate T with respect to the shaft rotation speed in a non-lubricated environment is shown for the sliding members of Example 1 and the comparative example.

[0177] like Figure 13 and Figure 14 As shown, a trend was observed: as the shaft speed increased, the amount of wear increased, and the temperature also rose. The sliding member of the comparative example had W = 0.06-0.07 mm and T = 0.7-1.8°C / second. In contrast, the sliding member of Example 1 had W = 0.02-0.04 mm and T = 0.2-1.4°C / second, confirming less wear and heat generation. Furthermore, the sliding member of Example 5 also had W = 0.02-0.04 mm. The amount of wear due to friction was roughly equivalent in Example 1, where the metal substrate 11 had no joints, and in Example 5, where the metal substrate 11 had joints.

[0178] Figure 15 The temporal changes in the bearing back surface temperature when the sliding members of Example 1 and the comparative example are operated at a shaft speed of 30,000 rpm are shown. Figure 16 The following shows the temporal changes in power consumption of the sliding members of Examples 1 and 5 and the comparative example when the sliding members are operated at a shaft rotation speed of 30,000 rpm.

[0179] like Figure 15 and Figure 16 As shown, the sliding component of the comparative example exhibits a rapid temperature rise from the initial stage of operation, with power consumption due to friction fluctuating dramatically between 400 and 700 W. Meanwhile, the sliding component of Example 1 exhibits a slower temperature rise to 120°C than the sliding component of the comparative example, and power consumption remains stable at approximately 200 W from the initial stage. The lack of an inner diameter-facing projection in the sliding component of Example 1 presumably avoids the effects of localized contact with the mating shaft. Furthermore, while power consumption in the sliding component of Example 5 is higher than that of Example 1 only in the initial stage, it gradually decreases and stabilizes. Power consumption due to friction is roughly equivalent in Example 1, where the metal substrate 11 has no joints, and Example 5, where the metal substrate 11 has joints. It is speculated that the presence of joints in the metal substrate 11 of the sliding component of Example 5 facilitates heat dissipation from the friction surface, leading to a gradual decrease and stabilization of power consumption.

[0180] Figure 17 The change in wear amount relative to shaft speed is shown for the sliding members of Example 1 and Example 2. Figure 18 The change of the bearing backside temperature rise rate is shown. Figure 19The change in wear amount relative to shaft speed is shown for the sliding members of Examples 3 and 4. Figure 20 Shows the change in the temperature rise rate of the bearing back surface.

[0181] As shown in Examples 17 to 20, polishing improved the inner diameter roundness. In the high rotation speed range of 10,000 to 20,000 rpm, the wear of the sliding components in Examples 1 and 3 was suppressed to a low of approximately 0.01 mm, and the temperature rise rate was suppressed to a low of approximately 0.5°C / second. In particular, Example 1, which contained MoS2, showed a significant wear reduction compared to the other products. It is speculated that the addition of Co-Mo-Si and MoS2, which constitute the Laves phase, forms a sulfide film even in a non-lubricated environment, contributing to wear reduction.

[0182] On the other hand, when the shaft speed reaches the 30,000 rpm range, there is virtually no difference in wear or heat generation, regardless of whether or not the shaft is polished. This is believed to be due to shaft vibration. Specifically, as the shaft speed gradually increases from a stationary state, vibrations caused by imbalance occur. Further increases in shaft speed lead to violent self-excited vibrations, where the shaft rotates through whirling while simultaneously orbiting within the bearing clearance. Therefore, the effects of shaft vibration caused by increased rotation and gap changes caused by heat generation can be cited.

[0183] While the embodiments and modifications have been described above by way of example, the scope of the present technology is not limited thereto and changes and modifications may be made according to the purpose within the scope of the claims. Furthermore, the embodiments and modifications may be appropriately combined within the scope of not causing inconsistencies in the processing contents.

Claims

1. A sliding member, characterized in that: have: Cylindrical metal substrate, A seamless porous layer formed on the inner peripheral surface of the metal substrate, and a sliding layer covering the porous layer, The porous layer is formed of a metal element or an alloy composition, The sliding layer is formed of a resin composition.

2. The sliding member according to claim 1, wherein The inner diameter roundness of the sliding layer is 50 μm or less.

3. The sliding member according to claim 1 or 2, characterized in that: Hard particle powder including a Laves phase composed of Co, Mo, and Si is dispersed in the sliding layer.

4. The sliding member according to claim 3, wherein At least one of MoS2 powder and bronze powder not containing a Laves phase is further dispersed in the sliding layer.

5. The sliding member according to claim 1 or 2, characterized in that: The resin composition comprises copper sulfide, a thermoplastic resin, molybdenum disulfide, graphite, aramid fiber, and a fluororesin as the balance, and contains greater than 3% by mass and less than 40% by mass of the copper sulfide, 0% by mass or more and less than 4% by mass of the thermoplastic resin, 0% by mass or more and 36% by mass or less of the molybdenum disulfide, 0% by mass or more and 10% by mass or less of the graphite, 0% by mass or more and 10% by mass or less of the aramid fiber, and the balance being the fluororesin.

6. The sliding member according to claim 1 or 2, characterized in that: The porous layer has: A matrix phase comprising Cu and Sn, and Hard particles are dispersed in the matrix phase and include a Laves phase composed of Co, Mo, and Si.

7. The sliding member according to claim 6, wherein: The porous layer also has a compound phase dispersed in the matrix phase and containing Co, Fe, Ni, Si, and Cr.

8. The sliding member according to claim 1 or 2, characterized in that: The ratio of the thickness of the porous layer to the thickness of the sliding layer is 6:4 to 8:

2.

9. The sliding member according to claim 1 or 2, characterized in that: The metal substrate also has no seams.

10. The sliding member according to claim 1 or 2, characterized in that: The metal substrate has a seam.

11. A bearing, characterized in that: have: Cylindrical metal substrate, A seamless porous layer formed on the inner peripheral surface of the metal substrate, and a sliding layer covering the porous layer, The porous layer is formed of a metal element or an alloy composition, The sliding layer is formed of a resin composition.

12. A method for manufacturing a sliding member having no joints in the sliding surface. It is characterized by: include: The step of disposing a cylindrical or cylindrical jig inside a cylindrical metal substrate and filling a gap between the inner peripheral surface of the metal substrate and the outer peripheral surface of the jig with raw material powder for the porous layer; a step of sintering the raw material powder to form a seamless porous layer composed of a metal element or an alloy composition on the inner peripheral surface of the metal substrate; a step of impregnating the surface of the porous layer with a raw material resin of the sliding layer; and A step of baking the raw resin to form a sliding layer comprising a resin composition covering the porous layer.

13. The method according to claim 12, characterized in that The method further includes pressing a cylindrical core rod into the inner side of the sliding layer while constraining the outer peripheral surface of the metal substrate by a die, thereby polishing the inner peripheral surface of the sliding layer to an inner diameter roundness of 50 μm or less.

14. The method according to claim 12 or 13, characterized in that In the step of filling the raw material powder, the raw material powder is filled into the gap while the jig is rotated and / or while ultrasonic vibration is applied to the jig.

15. The method according to claim 12 or 13, characterized in that In the step of sintering the raw material powder, the metal substrate is placed in a heating furnace together with the jig to sinter the raw material powder.

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