Sliding member and method of manufacturing a sliding member

Abstract

A sliding member includes a cylindrical metal base material, a porous layer formed on an inner peripheral surface of the metal base material, and a sliding layer covering the porous layer. The porous layer is formed of a metal simple substance or an alloy composition. The sliding layer is formed of a resin composition. The sliding member has a region in which the resin composition is not present and in which a non-porous layer formed of the metal simple substance or the alloy composition is exposed on a part of the inner peripheral surface.

Description

Technical Field

[0001] This disclosure relates to sliding members and methods for manufacturing sliding members. Background Technology

[0002] Currently, from the perspective of energy efficiency and CO2 emissions, there is a growing trend of replacing traditional engine-powered vehicles with electric vehicles (EVs) powered by batteries and electric motors. The output of an electric motor depends on its speed and torque; increasing the speed can suppress torque and reduce size. Therefore, high-speed rotation of the electric motor is indispensable for miniaturization, weight reduction, and power efficiency. Furthermore, for automotive air conditioning systems that support vehicle comfort, the demand for miniaturization and weight reduction of the electric compressor with its built-in drive motor is becoming increasingly strong.

[0003] The Association for Research on Automotive Power Transmission Technology (TRAMI), a group of Japanese automakers and other stakeholders, announced that it will shift its research focus from internal combustion engines to electric vehicle (EV) motors and related technologies. Currently, EV motors operate at around 13,000 rpm, but it is predicted that they will reach over 20,000 rpm in the near future, and research is underway towards ultra-high-speed rotation of 30,000–50,000 rpm. Specifically, for EV drive motors and electric compressors, the need for high-speed rotation is being addressed to balance miniaturization, lightweight design, and high output.

[0004] In rotating machinery that supports the main shafts of motors, compressors, and other similar components, bearings, seals, and other elements supporting the rotating parts play a crucial role. Over time, the sliding surfaces of these mechanical components deteriorate, leading to increased friction and wear. This results in a temperature rise due to heat generation, causing various parts of the rotating machinery to deteriorate and eventually fail to meet their functional requirements and reach the end of their lifespan. Furthermore, if the friction and heat generated by the high-speed rotation of the motor cause oil to leak from the bearings supporting the rotating shaft, or if foreign matter gets into the gaps, the temperature and vibration of the sliding surfaces become abnormally high, and the surface of the sliding material melts, leading to seizing. Thus, the performance of mechanical components deteriorates, and most failures are primarily caused by friction and wear. 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, ranging from conditions with only liquefied refrigerant to near-dry conditions.

[0005] Therefore, in boundary lubrication environments where boundary lubrication is difficult to achieve due to high-speed rotation of the drive system and shaft eccentricity, sliding bearings with excellent wear resistance and seizing resistance are required. Furthermore, since the dimensional accuracy of the bearing, such as the clearance between the shaft and the bearing, the shape of the bearing's inner diameter surface in contact with the shaft, and the presence or absence of protrusions caused by the mating seam, greatly affects the machine's lifespan, high-precision assembly is also required for sliding bearings.

[0006] In addition, for sliding bearings used in compressors, the operating environment around the bearings has become more stringent due to the switch to new refrigerants accompanying Freon restrictions and global warming countermeasures, thus requiring bearings with higher performance.

[0007] Japanese Patent Application Publication No. 2018-179049 proposes the use of rolling bearings in automotive parts and other components requiring high-speed rotation. However, rolling bearings have a shorter lifespan compared to sliding bearings, therefore, sliding bearings with a longer lifespan that can be used even at high speeds are desired.

[0008] As a sliding component with excellent wear resistance and anti-seize properties in high-speed rotation areas, the applicant of this application has proposed a sliding component without joints on the sliding surface and a method for manufacturing the same (Japanese Patent Application No. 2023-026107). Summary of the Invention

[0009] A sliding member and a method for manufacturing the sliding member that are expected to suppress temperature rise in the high-speed rotation region compared with the sliding member proposed in Japanese Patent Application No. 2023-026107.

[0010] One embodiment of the sliding member includes:

[0011] Cylindrical metal substrate,

[0012] A porous layer formed on the inner peripheral surface of the metal substrate, and

[0013] A sliding layer covering the porous layer,

[0014] The porous layer is formed from a metallic element or an alloy composition.

[0015] The sliding layer is formed of a resin composition.

[0016] The sliding member has a region on its inner circumferential surface where the resin composition is absent and a non-porous layer formed of the elemental metal or alloy composition is exposed.

[0017] One embodiment of the bearing includes:

[0018] Cylindrical metal substrate,

[0019] A porous layer formed on the inner peripheral surface of the metal substrate, and

[0020] A sliding layer covering the porous layer,

[0021] The porous layer is formed from a metallic element or an alloy composition.

[0022] The sliding layer is formed of a resin composition.

[0023] The bearing has a region on its inner circumferential surface where the resin composition is absent and a non-porous layer formed of the elemental metal or alloy composition is exposed.

[0024] One embodiment of a method for manufacturing a sliding member includes:

[0025] The step of forming a porous layer composed of a metallic element or alloy composition on one side of a metal substrate;

[0026] The step of rolling up the metal substrate with the porous layer as the inside to form a cylindrical shape;

[0027] The step of welding the joint portion from the outer diameter side of the metal substrate, wherein the porous layer on the joint portion melts to form a non-porous layer formed of the elemental metal or alloy composition; and,

[0028] The step of impregnating the surface of the porous layer with the raw resin of the sliding layer and calcining the raw resin to form a sliding layer composed of a resin composition covering the porous layer, wherein, since the surface of the non-porous layer is not impregnated with the raw resin, a region is formed on a portion of the inner circumferential surface of the sliding member where the resin composition is absent and the non-porous layer is exposed.

[0029] One embodiment of a method for manufacturing a sliding member includes:

[0030] The step of forming a porous layer composed of a metallic element or alloy composition on one side of a metal substrate;

[0031] The step of impregnating the surface of the porous layer with the raw material resin of the sliding layer and calcining the raw material resin to form a sliding layer composed of a resin composition covering the porous layer;

[0032] The steps of rolling up the metal substrate with the sliding layer inside to form a cylindrical shape; and,

[0033] The step of welding the joint portion from the outer diameter side of the metal substrate, wherein the porous layer on the joint portion melts to form a non-porous layer formed of the metal element or alloy composition, and the sliding layer on the joint portion peels off, thereby forming a region on a portion of the inner circumferential surface of the sliding member where the resin composition is absent and the non-porous layer is exposed. Attached Figure Description

[0034] Figure 1 This is a perspective view showing a simplified structure of a sliding member in one embodiment.

[0035] Figure 2 This is a photographic image obtained by taking a picture of the welded part of a sliding member in one embodiment from the outer peripheral side.

[0036] Figure 3 It is a photographic image obtained by taking a picture of the area corresponding to the welded part of the sliding member of one embodiment from the inner peripheral side.

[0037] Figure 4 It is an optical microscope photograph of the cross-sectional structure of the area corresponding to the weld before the formation of the sliding layer (resin impregnation and calcination).

[0038] Figure 5 This is a backscattered electron composition image of the cross-sectional structure of a sliding member in one embodiment, excluding the welded portion.

[0039] Figure 6 This is a flowchart illustrating an example of a method for manufacturing a sliding member according to one embodiment.

[0040] Figure 7 This is a flowchart illustrating another example of a method for manufacturing a sliding member according to one embodiment.

[0041] Figure 8 This diagram illustrates the raw material powder distribution process and the porous layer sintering process.

[0042] Figure 9 This is a diagram used to illustrate the resin impregnation process.

[0043] Figure 10 This is a diagram used to illustrate the polishing process.

[0044] Figure 11 This is a diagram showing the simplified structure of a high-speed rotating wear testing machine.

[0045] Figure 12 This is a diagram illustrating the location of the load point (load area A) during measurement in a high-speed rotational wear test for the sliding member in an embodiment.

[0046] Figure 13This is a table summarizing the composition of the sliding members in the embodiments and comparative examples 1 to 3.

[0047] Figure 14 The graph shows the time variation of bearing temperature measured at a shaft speed of N=15000 rpm for the sliding member of the embodiment and comparative examples 1 to 3.

[0048] Figure 15 The graph shows the time variation of bearing temperature measured at a shaft speed of N=20000 rpm for the sliding member of the embodiment and comparative examples 1 to 3.

[0049] Figure 16 The graph shows the time variation of bearing temperature measured at a shaft speed of N=25000 rpm for the sliding member of the embodiment and comparative examples 1-3.

[0050] Figure 17 The graph shows the time variation of bearing temperature measured at a shaft speed of N=30000 rpm for the sliding member of the embodiment and comparative examples 1 to 3.

[0051] Figure 18 The graph shows the time variation of bearing temperature measured at a shaft speed of N = 35000 rpm for the sliding member of the embodiment and Comparative Example 1.

[0052] Figure 19 The graph shows the change in temperature rise rate relative to shaft speed within the range of 10,000 to 50,000 rpm for the sliding member of the embodiments and comparative examples 1 to 3.

[0053] Figure 20 The graph shows the change in power consumption relative to shaft speed in the range of 10,000 to 50,000 rpm for the sliding member of the embodiments and comparative examples 1 to 3.

[0054] Figure 21 The graph shows the change of the rate of temperature rise relative to the shaft speed in a range near the shaft speed where a sharp increase in the rate of temperature rise and power consumption occurs, for the sliding member of the embodiments and comparative examples 1 to 3.

[0055] Figure 22 The graph shows the change in power consumption relative to the shaft speed in the vicinity of the shaft speed where the rate of temperature rise increases sharply, for the sliding member of the embodiments and comparative examples 1 to 3.

[0056] Figure 23 This is a diagram illustrating the location of the load point (load area B) during measurement in a high-speed rotational wear test for the sliding member in an embodiment.

[0057] Figure 24 The graph shows the change in temperature rise rate relative to shaft rotation speed, measured in load regions A and B, respectively, for the sliding member of the embodiment.

[0058] Figure 25 The graph shows the change in power consumption relative to shaft speed measured in load regions A and B, respectively, for the sliding member of the embodiment.

[0059] Figure 26 This is a graph showing the accuracy of the inner diameter of the sliding member in the embodiment.

[0060] Figure 27 This is a graph showing the accuracy of the inner diameter of the sliding member in Comparative Example 1. Detailed Implementation

[0061] The sliding member of the first embodiment includes:

[0062] Cylindrical metal substrate,

[0063] A porous layer formed on the inner peripheral surface of the metal substrate, and

[0064] A sliding layer covering the porous layer,

[0065] The porous layer is formed from a metallic element or an alloy composition.

[0066] The sliding layer is formed of a resin composition.

[0067] The sliding member has a region on its inner circumferential surface where the resin composition is absent and a non-porous layer formed of the elemental metal or alloy composition is exposed.

[0068] Based on this configuration, a region is provided on a portion of the inner circumferential surface of the sliding member that is devoid of resin composition and exposes a non-porous layer formed of elemental metal or alloy composition. As a result, since the surrounding resin composition is absent and the non-porous layer does not contain the multiple voids found in porous layers, this region has a recessed shape compared to the surrounding area, functioning as a groove. When using the sliding member, the inner surface of this groove does not contact the shaft, which is the object being slid, thus helping to reduce heat generation caused by friction. This suppresses temperature rise in high-speed rotating areas, improving the bearing's performance. Especially in the presence of lubricating oil or grease, an oil film is formed on the sliding surface due to the groove, further reducing heat generation compared to use in a dry environment.

[0069] Furthermore, because a region without resin composition and exposing a non-porous layer formed of elemental metal or alloy composition is provided on a portion of the inner circumferential surface of the sliding member, no protrusions caused by the joint appear on the sliding surface, thus reducing the torque generated at the joint during friction. This contributes to reduced power consumption and energy loss. Therefore, it can contribute to carbon neutrality.

[0070] In addition, bearings used in high-speed rotation environments, such as EV motors and electric compressors, can be replaced with sliding components as described in this embodiment, thereby contributing to miniaturization and weight reduction.

[0071] Furthermore, when conventional sliding members with seams on the sliding surface are applied to motors and compressors, an inner diameter cutting process (i.e., surface matching of the inner surface at the seam portion) is required. However, with the sliding member of this embodiment, since a region without resin composition and exposing a non-porous layer formed of elemental metal or alloy composition is provided on a portion of the inner circumferential surface of the sliding member, no protrusion caused by the seam appears on the sliding surface, thus reducing the inner diameter cutting process.

[0072] The sliding member of the second embodiment is based on the sliding member of the first embodiment, wherein,

[0073] The region is configured to extend from one end of the sliding member along its axial direction to the other end.

[0074] Based on this configuration, the heat generated by friction can be continuously reduced from one end of the axis to the other, thus further suppressing the temperature rise in the high-speed rotating region.

[0075] The sliding member of the third embodiment is a sliding member according to the first or second embodiment, wherein,

[0076] Hard particle powder is dispersed in the sliding layer, the hard particle powder comprising a Laffers phase composed of Co, Mo and Si.

[0077] The sliding member of the fourth embodiment is based on the sliding member of the third embodiment, wherein,

[0078] The sliding layer further disperses at least one of MoS2 powder and bronze powder without Laffers phase.

[0079] The sliding member of the fifth embodiment is a sliding member according to the first or second embodiment, wherein,

[0080] The resin composition comprises copper sulfide, thermoplastic resin, molybdenum disulfide, graphite, and aromatic polyamide fiber, with the balance being fluororesin. The resin composition comprises more than 3% by mass and less than 40% by mass of the copper sulfide, more than 0% by mass and less than 4% by mass of the thermoplastic resin, more than 0% by mass and less than 36% by mass of the molybdenum disulfide, more than 0% by mass and less than 10% by mass of the graphite, more than 0% by mass and less than 10% by mass of the aromatic polyamide fiber, with the balance being the fluororesin.

[0081] The sliding member of the sixth embodiment is a sliding member according to any one of the first to fifth embodiments, wherein,

[0082] The porous layer has the following characteristics:

[0083] The matrix phase, comprising Cu and Sn; and

[0084] Hard particles, dispersed in the matrix phase, comprising a Lafferse phase consisting of Co, Mo and Si.

[0085] The sliding member of the seventh embodiment is based on the sliding member of the sixth embodiment, wherein,

[0086] The porous layer further has:

[0087] The compound phase, which is dispersed in the matrix phase, comprises Co, Fe, Ni, Si and Cr.

[0088] The sliding member of the eighth embodiment is a sliding member according to any one of the first to seventh embodiments, wherein,

[0089] The ratio of the thickness of the porous layer to the thickness of the sliding layer is 6:4 to 8:2.

[0090] The bearing of the ninth embodiment includes:

[0091] Cylindrical metal substrate,

[0092] A porous layer formed on the inner peripheral surface of the metal substrate, and

[0093] A sliding layer covering the porous layer,

[0094] The porous layer is formed from a metallic element or an alloy composition.

[0095] The sliding layer is formed of a resin composition.

[0096] The bearing has a region on its inner circumferential surface where the resin composition is absent and a non-porous layer formed of the elemental metal or alloy composition is exposed.

[0097] The method for manufacturing a sliding member according to the tenth embodiment includes:

[0098] The step of forming a porous layer composed of a metallic element or alloy composition on one side of a metal substrate;

[0099] The step of rolling up the metal substrate with the porous layer as the inside to form a cylindrical shape;

[0100] The step of welding the joint portion from the outer diameter side of the metal substrate, wherein the porous layer on the joint portion melts to form a non-porous layer formed of the elemental metal or alloy composition; and,

[0101] The step of impregnating the surface of the porous layer with the raw resin of the sliding layer and calcining the raw resin to form a sliding layer composed of a resin composition covering the porous layer, wherein, since the surface of the non-porous layer is not impregnated with the raw resin, a region is formed on a portion of the inner circumferential surface of the sliding member where the resin composition is absent and the non-porous layer is exposed.

[0102] The method for manufacturing a sliding member according to the 11th embodiment includes:

[0103] The step of forming a porous layer composed of a metallic element or alloy composition on one side of a metal substrate;

[0104] The steps include impregnating the surface of the porous layer with the raw material resin of the sliding layer and calcining the raw material resin to form a sliding layer composed of a resin composition covering the porous layer;

[0105] The steps of rolling up the metal substrate with the sliding layer inside to form a cylindrical shape; and,

[0106] The step of welding the joint portion from the outer diameter side of the metal substrate, wherein the porous layer on the joint portion melts to form a non-porous layer formed of the metal element or alloy composition, and the sliding layer on the joint portion peels off, thereby forming a region on a portion of the inner circumferential surface of the sliding member where the resin composition is absent and the non-porous layer is exposed.

[0107] The method of the 12th embodiment is the method of the 10th or 11th embodiment, wherein,

[0108] The method further includes the following steps:

[0109] The outer peripheral surface of the metal substrate is constrained by a mold, and a cylindrical mandrel is pressed into the inner side of the sliding layer, thereby polishing (burnishing) the inner peripheral surface of the sliding layer.

[0110] Hereinafter, specific examples of embodiments will be described in detail with reference to the accompanying drawings. Furthermore, in this specification, unless otherwise specified, "%" related to composition refers to "mass %". Additionally, in this specification, unless otherwise specified, "A~B" (A and B are both numbers) means "A or more and B or less". Furthermore, in this specification, "main component" refers to a component that contains 50% or more by mass relative to the entire composition. Furthermore, in this specification, "hard particle powder" refers to powder in the mixed powder before sintering or powder dispersed in the resin composition of the sliding layer, and "hard particles" refers to particles in the porous layer after sintering. As described later, during sintering, Cu and Sn contained in the hard particle powder migrate to the matrix phase to a certain extent. Therefore, the content of hard particles in the porous layer varies depending on the amount of hard particle powder in the mixed powder, and the content of each constituent element in the hard particles differs from the content of each constituent element in the hard particle powder (hard particles are particles whose Sn and Cu content in the chemical composition is reduced to a certain extent compared to hard particle powder). Furthermore, in this specification, "joint" refers to the portion that connects two objects (or the two ends of an object) in a continuous manner, encompassing both welded and unwelded cases. In the unwelded case, "joint" refers to both the contact portion of the two objects (or the two ends of an object) and the portion separated by a small gap. Here, regarding "small gap," its specific width is not particularly limited as long as it is a gap that can be considered continuously connected when viewed as a whole; for example, it can be less than one-tenth, one-fiftieth, or one-hundredth of the overall length. Additionally, in this specification, the "joint" in the unwelded case is sometimes referred to as a "seam."

[0111] <Structure of sliding components>

[0112] Figure 1 This is a perspective view showing a simplified structure of the sliding member 10 in one embodiment. Figure 2 The photographic image is obtained by taking pictures of the welded part of the sliding member 10 from the outer peripheral side. Figure 3 The photographic image is obtained by taking pictures of the area of ​​the sliding member 10 corresponding to the welded part from the inner peripheral side. Figure 4 It is an optical microscope photograph of the cross-sectional structure of the area corresponding to the weld before the formation of the sliding layer (resin impregnation and calcination). Figure 5 This is a backscattered electron composition image of the cross-sectional structure of a sliding member, excluding the welded portion, according to one embodiment. Figure 4 and Figure 5 In the middle, the upper side of the paper corresponds to the inner circumference of the sliding member 10, and the lower side of the paper corresponds to the outer circumference of the sliding member 10.

[0113] like Figures 1-5 As shown, the sliding member 10 is, for example, a sliding bearing, comprising: a cylindrical metal substrate 11, a porous layer 12 formed on the inner circumferential surface of the metal substrate 11, and a sliding layer 13 covering the porous layer 12. The porous layer 12 is formed of a metallic element or an alloy composition, and the sliding layer 13 is formed of a resin composition.

[0114] like Figure 1 As shown, the sliding member 10, which serves as a sliding bearing, is supported by a shaft 20, which is the object being slidable, by a sliding layer 13 forming a cylindrical inner circumferential surface. The roundness of the inner diameter of the sliding layer 13 can be less than 50 μm or less than 20 μm. In this case, the friction at the inner circumferential surface of the sliding layer 13 is reduced, thus further reducing wear and heat generation.

[0115] The sliding member 10 can be applied to either the shaft 20 in a rotary motion or in a linear motion. For example, the sliding member 10 can also be used as a sliding part for oil in a linear motion, such as in a shock absorber of an automobile. Alternatively, the sliding member 10 can also be used as a sliding part for oil in a rotary motion, such as in a gear pump that delivers oil by rotating a gear-shaped component. The constituent elements of the sliding member 10 will be described in detail below.

[0116] like Figures 1-3 As shown, the metal substrate 11 has a cylindrical shape. The metal substrate 11 can be shaped into a cylindrical shape, for example, by rolling up a metal sheet, and then joining the seam portion 11a (see reference). Figure 2 The metal substrate 11 is manufactured by welding. The material of the metal substrate 11 is not particularly limited as long as it has the strength and shape stability to be used as a backing metal base material for bearings. For example, it can be low carbon steel (SPCC, SS400, etc.) or copper-plated steel plate with Cu plated on Fe-based plate.

[0117] The porous layer 12 has a 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 the thickness obtained by sintering at least two overlapping metal powders, for example, it can be less than 0.5 mm.

[0118] The sliding layer 13 is formed by impregnating a resin composition into the porous layer 12 to a predetermined thickness and then calcining the resin composition impregnated into the porous layer 12. The thickness of the sliding layer 13 (the thickness from the surface of the metal substrate 11) can be set to be on average thicker than the thickness of the porous layer 12 without exposing the porous layer 12. 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.

[0119] The resin composition of the sliding layer 13 contains a fluororesin as a main component. The fluororesin used as the base resin for the resin composition can be, for example, PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxyalkane), FEP (perfluoroethylene-propylene copolymer), EFFE (ethylene-tetrafluoroethylene copolymer), etc.

[0120] The resin composition may contain PTFE as a fluoropolymer as the main component, and other fluoropolymers such as PFA as optional additives. The content of other fluoropolymers included as optional components in the resin composition may be more than 0% by volume and less than 20% by volume.

[0121] Commercially available PTFE resins include Polyflon (registered trademark) D-210C, F-201 (manufactured by Daikinindustries, Ltd.), Fluon (registered trademark) AD911D (manufactured by Asahi Glass Co., Ltd.), Teflon (registered trademark) 31JR, 6C-J (manufactured by Du Pont-Mitsui Fluorochemicals Co. Ltd.), etc.

[0122] like Figure 5 As shown, in the resin composition of the sliding layer 13, hard particulate powder 13a containing a Laffers phase composed of Co, Mo, and Si can be dispersed. Here, the Laffers phase is an intermetallic compound based on the AB2 type, composed of elements A and B with an atomic radius ratio of approximately 1.2:1, and exists in three structures: MgZn2 (C14), MgCu2 (C15), and MgNi2 (C36). The Laffers phase composed of Co, Mo, and Si (more specifically, Co3Mo2Si) is a Laffers phase where element A is Mo, element B is Co, and 25% of Co is replaced by Si; it is a MgZn2 type with a hexagonal crystal structure. The Vickers hardness of the Laffers phase composed of Co3Mo2Si 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 hard Laffers phase composed of Co, Mo and Si precipitates on the friction surface and bears the load, thereby advantageously acting to reduce the wear of the sliding layer 13.

[0123] Furthermore, the Mo in the Laffers phase and the S in the lubricating oil can form a MoS2 sulfide coating on the friction surface. MoS2 is a known solid lubricant that can replace lead and improve frictional properties. Compared to the bonds between molybdenum and between molybdenum and sulfur, the bonds between sulfur are weaker. Therefore, when friction occurs, the bonds between sulfur selectively break, resulting in lubrication and effectively inhibiting wear. In addition, the Mo oxide formed on the friction surface due to the oxidation of Mo in the Laffers phase during sliding also plays a lubricating role and effectively inhibits wear.

[0124] In the resin composition of the sliding layer 13, at least one of molybdenum disulfide (MoS2) powder and bronze powder without the Lafferse phase may be further dispersed. As mentioned above, MoS2 is a known solid lubricant that can replace lead and improve frictional properties. Compared to the bonds between molybdenum and between molybdenum and sulfur, the bonds between sulfur are weaker. Therefore, when friction occurs, the bonds between sulfur selectively break, resulting in lubrication and effectively inhibiting wear.

[0125] As a variation, the resin composition of the sliding layer 13 may comprise copper sulfide (CuS), thermoplastic resin, molybdenum disulfide (MoS2), graphite, and aromatic polyamide fibers, with the balance being fluororesin (wherein the resin composition does not contain lithium phosphate). In this case, the resin composition may comprise more than 3% by mass and less than 40% by mass of copper sulfide, more than 0% by mass and less than 4% by mass of thermoplastic resin, more than 0% by mass and less than 36% by mass of molybdenum disulfide, more than 0% by mass and less than 10% by mass of graphite, more than 0% by mass and less than 10% by mass of aromatic polyamide fibers, with the balance being fluororesin.

[0126] By including copper sulfide as a metal sulfide in the resin composition forming the sliding layer 13, the heat dissipation characteristics of the sliding layer 13 are improved. This suppresses the temperature rise of the sliding layer 13 caused by the sliding of the object being slidable, and suppresses the deformation of the sliding layer 13 that accompanies the temperature rise.

[0127] Furthermore, by including copper sulfide in the resin composition forming the sliding layer 13, the strength of the sliding layer 13 is improved. It is known that by including carbon fiber filler in the resin composition forming the sliding layer, the strength of the resin layer is improved. Conversely, by including copper sulfide in the resin composition, the strength is improved in the same way as in the case where carbon fiber filler is included, even without it. By improving the strength of the sliding layer 13, deformation of the sliding layer 5 caused by the sliding of the object being slidable can also be suppressed.

[0128] When the deformation of the sliding layer 13 increases, the wear increases compared to when the deformation is smaller. Therefore, by suppressing the deformation of the sliding layer 13, the wear of the sliding layer 13 can be suppressed, and the wear resistance can be improved. In addition, by increasing the strength of the sliding layer 13, wear can also be suppressed. Moreover, by suppressing the wear of the sliding layer 13, the exposure of the porous layer 12 can be suppressed, and the dry contact between the porous layer 12 and the animal being slipped on, which is the main cause of biting and killing, can be suppressed, thus improving the bite resistance.

[0129] For copper sulfides, cuprous sulfide (Cu₂S) and copper(II) sulfide (CuS) are known. Cuprous sulfide (Cu₂S) is also stable above 1000°C. In contrast, copper(II) sulfide (CuS) transforms into cuprous sulfide (Cu₂S) around 200°C. When polytetrafluoroethylene (PTFE) is used as the resin, the resin composition 4 is heated to a temperature exceeding 327°C during the calcination of the sliding layer 13. Therefore, when the resin composition contains copper(II) sulfide (CuS), copper(II) sulfide (CuS) transforms into cuprous sulfide (Cu₂S) during the calcination of the sliding layer 13.

[0130] Therefore, the sliding layer 13 of the sliding member 10, which is the manufactured product, contains cuprous sulfide (Cu2S). However, cuprous sulfide (Cu2S) or copper sulfide (II) (CuS) can be used as raw materials for copper sulfide, but copper sulfide (II) (CuS) is preferred from the perspective of processability.

[0131] By further including molybdenum disulfide as a metal sulfide in the resin composition forming the sliding layer 13, the sliding characteristics relative to the object sliding in contact with the sliding layer 13 are improved. Furthermore, by including graphite in the resin composition forming the sliding layer 13, the sliding characteristics are also improved. Thus, it is possible to obtain sliding characteristics of the same degree as those of a sliding member containing Pb with a lead-free (Pb) composition. Hereinafter, a modified example of the resin composition of the sliding layer 13 will be described in detail.

[0132] [Copper sulfide: more than 3% by mass and less than 40% by mass]

[0133] To improve heat dissipation characteristics and strength, the resin composition forming the sliding layer 13 preferably contains more than 8% by mass and less than 40% by mass of copper sulfide. If the amount of copper sulfide added is less than 3% by mass and more than 40% by mass, the heat dissipation characteristics deteriorate, hindering the wear resistance characteristics. In addition, commercially available products include copper(II) (CuS) sulfide manufactured by Terada Yakusen Kogyo Co., Ltd., copper(II) (CuS) sulfide manufactured by Kanto Chemical Co., Ltd., and cuprous sulfide (Cu2S) manufactured by High Purity Chemical Research Institute Co., Ltd.

[0134] [Plastic resin: 0% to 4% by mass]

[0135] In a modified example of the resin composition of the sliding layer 13, the thermoplastic resin is not an essential additive, but its addition can improve the wear resistance and creep resistance, which are disadvantages of fluoropolymers, and is therefore preferred.

[0136] When thermoplastic resin is added, if the content exceeds 4% by mass, it will hinder the low-friction properties of the fluoropolymer. Furthermore, commercially available PPS resins, which are thermoplastic resins, include DIC Corporation's PQ-208 and KUREHA Corporation's Fortron (registered trademark) KPS.

[0137] [Graphite: 0% to 10% by mass]

[0138] In the resin composition of the sliding layer 13 in a modified example, graphite is not an essential additive, but it is expected to contribute to improved self-lubrication and heat resistance, low-friction properties, and wear resistance. However, if the addition of graphite exceeds 10% by mass, it will hinder the low-friction properties. Furthermore, commercially available products include UCP and CPB manufactured by Nippon Graphite Industries, Ltd., and the AT series manufactured by Oriental Industries, Ltd.

[0139] [Molybdenum sulfide: ≥0% by mass and ≤36% by mass]

[0140] In a modified example of the resin composition of the sliding layer 13, molybdenum disulfide (MoS2) is not an essential additive, but its addition can reduce frictional resistance.

[0141] When the amount of molybdenum disulfide added exceeds 36% by mass, the impregnation performance deteriorates during the impregnation process into porous layers. Furthermore, commercially available products include H / GMoS2 manufactured by Taiyo Mining Co., Ltd., and the molybdenum disulfide powder series manufactured by DAIZO CORPORATION.

[0142] [Aromatic polyamide fiber: 0% to 10% by mass]

[0143] In the resin composition of the sliding layer 13 in a modified example, the aramid fiber is not an essential additive, but is added to obtain mechanical strength. When aramid fibers are added, if the addition exceeds 10% by mass, uniform dispersion is hindered, resulting in reduced wear resistance. Furthermore, commercially available products include Kevlar (registered trademark) manufactured by DuPont-Toray Co., Ltd., and Twaron (registered trademark) from TEIJIN LIMITED.

[0144] As another variation, the resin composition of the sliding layer 13 may contain one or more of the following as additives: zinc compounds (ZnS (zinc sulfide), ZnO (zinc oxide), ZnSO4 (zinc sulfate, etc.), carbon fibers, iron oxide, barium sulfate, aromatic polyamide fibers, graphite, calcium compounds (CaCO3 (calcium carbonate), CaSO4 (calcium sulfate), Ca(OH)2 (calcium hydroxide), etc.), zinc, and zinc alloys. By including zinc compounds in the resin composition, deformation of the sliding layer 13 can be suppressed by increasing the elastic modulus, thus suppressing the increase or decrease in contact area due to deformation of the sliding layer 13 caused by external forces. Furthermore, by including zinc compounds in the resin composition... Carbon fibers can improve the value of dynamic friction, as well as the changes in static and dynamic friction, thus improving sliding characteristics. Including iron oxide in the resin composition can improve both wear resistance and elastic modulus. Including barium sulfate or aramid fibers in the resin composition can improve wear resistance without hindering the improvement of elastic modulus through the addition of zinc compounds. Including graphite in the resin composition can reduce frictional resistance without hindering the improvement of elastic modulus through the addition of zinc compounds. Including calcium compounds, zinc, or zinc alloys in the resin composition can improve wear resistance without hindering the improvement of elastic modulus through the addition of zinc compounds.

[0145] As a variation, the porous layer 12 may comprise a matrix phase containing Cu and Sn, and hard particles dispersed within the matrix phase. The porous layer 12 can be formed by sintering alloy powder, which is alloyed from mixed powders during spraying. By producing alloy powder, sintering of the powder promotes the formation of a neck, allowing the powder particles to bond sufficiently together. Furthermore, by producing alloy powder, the hard particles are refined and uniformly dispersed in the matrix phase. Additionally, if the hard particle powder 13a is dispersed in the aforementioned sliding layer 13, the porous layer 13 may not contain hard particles.

[0146] The matrix phase is a bronze alloy containing Cu as the main component and also Sn. The matrix phase can be composed of a solid solution of Cu, Sn, and Ni.

[0147] Bi particles can also be distributed at the grain boundaries of the matrix phase. In this case, on the friction surface where a portion of the porous layer 3 is exposed due to wear of the sliding layer 4, Bi exhibits the same self-lubricating effect as Pb in conventional lead bronze, acting as a lubricant between the two friction surfaces, thereby achieving friction reduction.

[0148] The hard particles may contain a Laffers phase composed of Co, Mo, and Si. It is believed that when the sliding layer 13 wears and a portion of the porous layer 12 is exposed, the hard particles dispersed in the matrix phase will experience a higher load than the soft bronze that forms the matrix phase. However, the hard Laffers phase, composed of Co, Mo, and Si, precipitates on the friction surface and bears the load, thus advantageously reducing the wear of the porous layer 12. Furthermore, Mo in the Laffers phase and S in the lubricating oil can form a MoS2 sulfide coating on the friction surface. MoS2 is a known solid lubricant material that helps improve frictional properties as a substitute for lead. Compared to the bonds between molybdenum and between molybdenum and sulfur, the bonds between sulfur are weaker. Therefore, when friction occurs, the sulfur bonds selectively break, resulting in lubrication and effectively suppressing wear. Additionally, the Mo oxide formed on the friction surface through the oxidation of Mo in the Laffers phase during sliding also contributes to lubrication and effectively suppresses wear.

[0149] When the porous layer 12 contains hard particles, the content of hard particles can be, for example, 40% by mass or less when the porous layer 12 as a whole is 100% by mass. When the porous layer 12 as a whole is 100% by mass, 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 wear reduction effect of the porous layer 12 as described above can be obtained. Furthermore, when the porous layer 12 as a whole is 100% by mass, the content of the Laffers phase composed of Co, Mo, and Si can be, for example, 0.1 to 20% by mass. When the sliding layer 13 contains hard particle powder 13a and the porous layer 12 does not contain hard particles, when the porous layer 12 as a whole is 100% by mass, the combined content of Cu and Sn can be 99.9% or more.

[0150] The porous layer 3 may further contain a compound phase dispersed in the matrix phase. The compound phase may include Co, Fe, Ni, Si, and Cr. Forming the compound phase in the matrix phase increases the hardness of the matrix phase, which advantageously contributes to improved resistance to biting.

[0151] As the sliding member 10 of this embodiment, there are four types: (1) the porous layer 12 contains hard particles but the sliding layer 13 does not contain hard particle powder 13a; (2) the porous layer 12 does not contain hard particles but the sliding layer 13 contains hard particle powder 13a; (3) the porous layer 12 contains hard particles and the sliding layer 13 contains hard particle powder 13a; and (4) the porous layer 12 does not contain hard particles and the sliding layer 13 does not contain hard particle powder 13a. In any of the types (1) to (3), when the total of the porous layer 12 and the sliding layer 13 (i.e., the portion obtained by removing the metal substrate 11 from the total of the sliding member 10) is set to 100% by mass, the total content of hard particles and the content of hard particle powder 13a can be 1 to 20% by mass, for example, it can be 15% by mass.

[0152] like Figure 3 and Figure 4 As shown, a portion of the inner circumferential surface of the sliding member 10 has a non-porous layer 14 formed of a metallic element or alloy composition, which is free of resin composition (see reference). Figure 4 Area 15. Figure 3 In the example shown, region 15, where no resin composition is present, is only provided once on the inner circumferential surface of the sliding member 10, but multiple regions may also be provided. For example... Figure 3 As shown, the region 15 where no resin composition is present can be provided such that it extends axially from one end of the sliding member 10 to the other end. The region 15 where no resin composition is present can be provided at the joint 11a of the metal substrate 11 (see reference). Figure 2 The non-porous layer 14 can be formed from the same elemental metal or alloy composition as the porous layer 12.

[0153] like Figure 4 As shown, the non-porous layer 14 is formed by melting the metallic element or alloy composition constituting the porous layer 12, and therefore has a shape where the inner diameter surface is recessed compared to the surrounding surface. The depth D of the recessed space of the non-porous layer 14 can be, for example, 0.2 to 0.3 mm. The width (circumferential length) W of the non-porous layer 14 can be 0.1 to 10% of the inner circumferential length of the sliding member 10. For example, when the inner circumferential length of the sliding member 10 is 60 to 70 mm, the width W of the non-porous layer 14 can be 1.0 mm to 3.0 mm.

[0154] <Manufacturing Method of Sliding Components>

[0155] Next, refer to Figure 6 , Figures 8-10 An example of a method for manufacturing a sliding member 10 having such a structure will be described. Figure 6This is a flowchart illustrating an example of a method for manufacturing the sliding member 10. Figure 8 This diagram illustrates the raw material powder distribution process and the porous layer sintering process. Figure 9 This diagram illustrates the resin impregnation process. Figure 10 This is a diagram used to illustrate the polishing process.

[0156] like Figure 6 and Figure 8 As shown, firstly, the raw material powder of the porous layer 12 is dispersed on one side of the plate-shaped metal substrate (step S10).

[0157] The raw material powder can be a first powder containing Cu and Sn, or a mixed powder formed by mixing the first powder with hard particulate powder containing a Laffers phase composed of Co, Mo and Si, or a mixed powder formed by further mixing a second powder containing Cu, Co, Fe, Ni, Si and Cr on the basis of the first powder and hard particulate powder.

[0158] Here, the first powder is a bronze alloy powder containing Cu as the main component and also containing Sn. The first powder may further 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 (i.e., step S20), and Bi exhibits the same self-lubricating effect as Pb in conventional lead bronze, thus achieving low friction. In addition, when the first powder contains P, oxygen mixed in with copper can be removed (deoxidized), thereby suppressing hydrogen embrittlement. The content of each constituent element in the first powder can be Sn: 10-11% by mass, Cu: balance. When Bi is further contained, Bi is preferably 7-9% by mass, and when P is contained, P is preferably 0.02% by mass or less. 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.

[0159] Hard particle powder is an alloy powder containing a Laffers phase composed of Co, Mo, and Si, and Cu, and specifically 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 solid-state temperature of hard particle powder without Sn reaches around 1450°C, but by containing Sn, the solid-state temperature of the hard particle powder can be lowered, allowing solid-state sintering of the hard particle powder to the backing metal substrate to around 800°C. Furthermore, the Sn encapsulated within the hard particle powder dissolves and diffuses into the Cu-Sn matrix phase formed from the first powder during sintering. By advancing sintering through powder shrinkage facilitated by Sn, solid solution strengthening can be achieved through both the Sn in the matrix phase and the Sn encapsulated within the hard particle powder. When the total content of the hard particle powder is 100% by mass, the content of each constituent element in the hard particle powder can be Co: 14-20% by mass, Mo: 24-28% by mass, Si: 3-7% by mass, Fe: 2-16% by mass, Cr: 1-10% by mass, Cu: balance. When Sn is included, when the total content of the hard particle powder is 100% by mass, the content of each constituent element in the hard particle powder can be Co: 14-20% by mass, Mo: 24-28% by mass, Si: 3-7% by mass, Fe: 2-16% by mass, Cr: 1-10% by mass, Sn: 1-15% by mass, Cu: balance. When the total content of the raw material powder is 100% by mass (i.e., when the sliding layer 12 is 100% by mass), the amount of hard particle powder can be 1-40% by mass, preferably 1-3% by mass. Since Cu and Sn dissolve from the hard particle powder during sintering, the content of hard particles in the sliding layer 12 will vary depending on the amount of hard particle powder in the raw material powder.

[0160] The second powder is an alloy powder containing Cu as the main component, and also containing Co, Fe, Ni, Si, and Cr. The second powder may further contain Sn, for example, more than 1% by mass of Sn. The solid-state temperature of the second powder without Sn reaches approximately 1240°C, but by containing Sn, the solid-state temperature of the second powder can be lowered, allowing solid-state sintering of the second powder to the backing metal substrate to approximately 800°C. When Sn is included, and the second powder as a whole is set at 100% by mass, the content of each constituent element in 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, Cu: balance. When the raw material powder contains the second powder, when the total raw material powder is set to 100% by mass, the amount of the second powder can be 2 to 38% by mass, preferably 10 to 38% by mass, and more preferably 17 to 19% by mass.

[0161] When the total amount of raw material powder is set to 100% by mass, the amount of hard particle powder can be 1 to 40% by mass, and the amount of the second powder can be 15 to 18% by mass. Under this condition, excellent shearing processability can be achieved.

[0162] The first powder, the hard particulate powder, and the second powder can be manufactured by spraying, for example, using a gas atomization method. In the gas atomization method, the heat source for melting can be high frequency, and for the crucible (with a nozzle at the bottom), zirconia can be used.

[0163] The particle size of the first powder can be, for example, 45 μm to 180 μm. The particle size of the hard granular powder can be micron powder with a particle size of less than 53 μm. The particle size of the second powder can be 53 μm to 150 μm. Here, "particle size" refers to the particle size distribution determined by laser diffraction scattering using the MicrotracBEL MT3300EXII particle size distribution measuring device. This measurement method is based on the test steps after the process of extracting powder from paste in JIS Z3284-2, "4.2.3 Laser Diffraction Particle Size Distribution Measurement Test".

[0164] Next, the raw material powder dispersed on the metal substrate 11 is sintered at 800~900°C to form a porous layer 12 (step S20). As described above, the solid-state temperatures of the Sn-free hard particle powder and the second powder are around 1450°C and 1240°C, respectively. However, by including Sn, the solid-state temperatures of the hard particle powder and the second powder can be lowered, allowing the hard particle powder and the second powder to undergo solid-state sintering onto the metal substrate (backing metal base material) at around 800°C. Furthermore, the Sn encapsulated in the hard particle powder dissolves and diffuses into the Cu-Sn matrix phase 10 formed by the first powder during sintering. By advancing sintering through powder shrinkage with the aid of Sn, solid solution strengthening from the Sn in the matrix phase 10 and the Sn encapsulated in the hard particle powder is exhibited, ultimately forming a high-strength alloy.

[0165] Next, after the metal substrate 11 is rolled up with the porous layer 12 inside and shaped into a cylindrical shape (step S30), the seam portion 11a is welded from the outer diameter side of the metal substrate 11 (step S40). The welding method can be TIG welding (argon welding) or laser welding (pulse welding). At this time, the porous layer 12 on the seam portion 11a melts due to the heat during welding, thereby causing the multiple voids contained in the porous layer 12 to collapse, forming a non-porous layer 14 formed of a metallic element or alloy composition. No seam appears on the inner diameter surface. At the non-porous layer 14, the apparent volume is reduced by an amount corresponding to the voids contained in the porous layer 12, thus resulting in a shape where the inner diameter surface is concave than the surrounding porous layer 12.

[0166] Although not mandatory, it is permissible to perform welding on the butt joint portion 11a (step S40) by using mold 41 (see reference). Figure 10 The outer peripheral surface of the metal substrate 11 is constrained and a cylindrical mandrel 42 is pressed into the inner side of the porous layer 12, thereby polishing the inner peripheral surface of the porous layer 12.

[0167] Next, the raw material resin of the sliding layer 13 is impregnated onto the surface of the porous layer 12 (step S50). Specifically, for example, as... Figure 9As shown, a predetermined amount of resin composition may be supplied to a porous layer 12 formed on the inner peripheral surface of a metal substrate 11, and the resin composition may be pressed onto the porous layer 12 by the rotational pressure of an impregnation roller, thereby impregnating the porous layer 12 with the resin composition. The resin composition supplied to the porous layer 12 may contain at least one of the following: hard particulate powder 13a comprising a Laffers phase composed of Co, Mo, and Si, and molybdenum disulfide (MoS2) powder. As a variation, the resin composition may contain copper sulfide as an additive, and may further contain molybdenum disulfide, or may contain graphite, aromatic polyamide fibers as other additives. The amount of resin composition supplied to the porous layer 12 is the amount that covers the porous layer 12 to a thickness that does not expose the surface of the sliding layer 13 after the resin composition is calcined (described later).

[0168] At this time, since the metal element or alloy composition constituting the porous layer 12 melts, the surface of the non-porous layer 14 will not become a state in which the raw material resin is impregnated between the pores, but rather a state in which the raw material resin is only on the non-porous layer 14.

[0169] Next, the resin composition is heated to a temperature exceeding the melting point of the resin contained in the resin composition, causing the resin to melt and the organic solvent to evaporate, followed by resin curing, thereby forming a sliding layer 13 composed of the resin composition covering the porous layer 12 (step S60). The process of forming the sliding layer 13 by heating the resin composition at a specified temperature is called calcination. Furthermore, the polytetrafluoroethylene used as the resin has a melting point of 327°C. Alternatively, the sliding layer 13 can be calcined by heating the resin composition in a calcination furnace at a temperature exceeding the melting point of polytetrafluoroethylene (e.g., 400~500°C).

[0170] At this point, the surface of the non-porous layer 14 becomes molten due to welding, making it easy for the resin composition to peel off from the non-porous layer 14. The resin composition can be peeled off from the non-porous layer 14 non-contactly by gravity or wind after the sliding layer 13 is formed, or it can be peeled off by sweeping with a brush or the like. As the resin composition peels off from the non-porous layer 14, a region 15 is formed on the inner circumferential surface where the resin composition is absent and the non-porous layer 14 is exposed.

[0171] Next, refer to Figure 10 By using mold 41 to constrain the outer peripheral surface of metal substrate 11 and pressing a cylindrical mandrel 42 into the inner side of sliding layer 13, the inner peripheral surface of sliding layer 13 is polished (burnished) to achieve an inner diameter roundness of 50 μm or less (step S70). Thus, a sliding member 10 having the above structure is manufactured (see...). Figures 1-5 ).

[0172] Next, refer to Figure 7 Other examples of methods for manufacturing sliding member 10 will be described. Figure 7 This is a flowchart illustrating another example of a method for manufacturing the sliding member 10.

[0173] Similar to an example of the manufacturing method described above, firstly, raw material powder of porous layer 12 is dispersed on one surface of a metal substrate (step S10), and then the raw material powder dispersed on the metal substrate 11 is sintered to form porous layer 12 (step S20).

[0174] Next, as Figure 7 As shown, a predetermined amount of resin composition is supplied to the porous layer 12, and the resin composition is pressed onto the porous layer 12, thereby impregnating the porous layer 3 with the resin composition (step S150). The amount of resin composition supplied to the porous layer 12 is the amount that covers the porous layer 12 to a thickness that does not expose the surface of the sliding layer 13 after the resin composition is calcined (described later).

[0175] Next, the resin composition is heated to a temperature exceeding the melting point of the resin contained in the resin composition to melt the resin and evaporate the organic solvent, and then the resin is cured to form a sliding layer 13 composed of the resin composition covering the porous layer 12 (step S160).

[0176] Next, after the metal substrate 11 is rolled up with the sliding layer 13 inside and shaped into a cylindrical shape (step S130), the joint portion 11a is welded from the outer diameter side of the metal substrate 11 (step S140). The welding method can be TIG welding (argon welding) or laser welding (pulse welding). At this time, the porous layer 12 on the joint portion 11a melts due to the heat during welding, thereby causing the multiple voids contained in the porous layer 12 to collapse, forming a non-porous layer 14 made of a metal element or alloy composition, and the resin composition on the joint portion 11a will peel off, thereby forming a region 15 on a part of the inner circumferential surface where there is no resin composition and the non-porous layer 14 is exposed.

[0177] Next, refer to Figure 10 By using mold 41 to constrain the outer peripheral surface of the metal substrate 11 and pressing a cylindrical mandrel 42 into the inner side of the sliding layer 13, the inner peripheral surface of the sliding layer 13 is polished (burnished) to achieve an inner diameter roundness of 50 μm or less (step S70). Thus, a sliding member 10 having the above structure is manufactured (see...). Figures 1-5 ).

[0178] According to the present embodiment described above, a region 15 is provided on a portion of the inner circumferential surface of the sliding member 10, where a non-porous layer 14 formed of a metallic element or alloy composition is exposed, free of resin composition. Since the surrounding resin composition is absent and the non-porous layer does not contain the multiple voids found in porous layers, this region has a recessed shape compared to the surrounding area, functioning as a groove. When using the sliding member 10, the inner surface of this groove does not contact the shaft, which is the object being slid, thus helping to reduce heat generation caused by friction. This suppresses temperature rise in high-speed rotating areas, improving the bearing's performance. Especially in the presence of lubricating oil or grease, an oil film is formed on the sliding surface due to the groove, further reducing heat generation compared to use in a dry environment.

[0179] Furthermore, since a region 15 is provided on a portion of the inner circumferential surface of the sliding member 10, containing a non-porous layer 14 formed of a metallic element or alloy composition and free of resin composition, no protrusions caused by the joint appear on the sliding surface, thus reducing the torque generated at the joint during friction. This helps to reduce power consumption and minimize energy loss. Therefore, it can contribute to carbon neutralization.

[0180] In addition, bearings used in high-speed rotation environments such as EV motors and electric compressors can be replaced with the sliding member 10 of this embodiment instead of conventional rolling bearings, thereby contributing to miniaturization and weight reduction.

[0181] Furthermore, when conventional sliding members with seams on the sliding surface are applied to motors and compressors, an inner diameter cutting process (i.e., surface matching of the inner surface at the seam portion) is required. However, with the sliding member 10 of this embodiment, since a region 15 is provided on a portion of the inner circumferential surface of the sliding member 10, which is free of resin composition and exposes a non-porous layer 14 formed of elemental metal or alloy composition, no protrusions caused by the seam appear on the sliding surface, thus reducing the inner diameter cutting process.

[0182] Furthermore, according to this embodiment, since the region 15 without the resin composition is provided such that it extends from one end of the sliding member 10 in the axial direction to the other end, the effect of reducing heat generation caused by friction can be continuously obtained from one end to the other in the axial direction. As a result, it is possible to further suppress the temperature rise in the high-speed rotating region.

[0183] Furthermore, according to this embodiment, the region 15 where there is no resin composition is recessed compared to the surrounding area, acting as a groove. Since this region 15 is formed simultaneously with the heat during welding of the joint portion 11a of the metal substrate 11, the number of steps can be reduced compared to the case where the sliding layer is processed into an uneven shape after the sliding layer is formed.

[0184] <Example>

[0185] Next, specific embodiments of this implementation will be described.

[0186] (Fabrication of sliding components)

[0187] First, the raw material powder for porous layer 12 is prepared by removing coarse powder with a particle size of 150 μm or larger from bronze powder (amorphous, grade: CP-301) manufactured by Fukuda Metal Foil Powder Industry Co., Ltd. The chemical composition of the bronze powder is Cu-10Sn.

[0188] Next, as an example, after dispersing the raw material powder of the porous layer 12 on the copper-plated steel plate, it was sintered at 880°C to form the porous layer 12. Next, to obtain an inner diameter of Φ20mm, the steel plate with the porous layer 12 was slit with a slit width of 67.6mm. Then, while applying pressure to the slitted steel plate via a side roll, it was shaped into a cylindrical shape in the width direction, and the joint portion of the steel plate was argon-welded from the outer diameter side. After welding, it was water-cooled, deburred, sized, and cut into 10mm length pieces to obtain a cylindrical metal substrate 11 with the porous layer 12 formed on its inner circumferential surface. Then, referring to… Figure 10 Using an Amsler testing machine, the outer peripheral surface of the metal substrate 11 is constrained by the mold 41 and the mandrel 42 is pressed into the inner side of the porous layer 12, thereby applying a load to the inner peripheral surface of the porous layer 12 for correction (polishing).

[0189] Next, resin is impregnated onto the inner circumferential surface of the porous layer 12. The impregnated resin consists of graphite powder: 1.1% by mass, hard particle powder containing a Laffers phase composed of Co, Mo, and Si: 15% by mass, and the balance being PTFE resin. To improve self-lubricating properties, MoS2 powder: 15% by mass is added. The chemical composition of the hard particle powder is Cu-4.5Sn-5Si-15Fe-16Co-4Cr-26Mo, with a particle size of less than 53μm. The graphite powder is from Nippon Graphite (brand name: CPBW-5).

[0190] As a resin impregnation method, refer to Figure 9 Resin is applied to the inner circumferential surface of the porous layer 12 using a scraper, while a Φ11.7 rolling mandrel is used to press it down, and the resin is impregnated into the porous layer 12 by the rolling rotation pressure. Then, it is calcined in a calcining furnace at a calcination temperature of 480℃ and a conveyor belt speed of 1000mm / min.

[0191] Next, refer to Figure 10Using an Amsler testing machine, the outer peripheral surface of the metal substrate 11 is constrained by the mold 41 and the mandrel 42 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).

[0192] Through the above manufacturing process, the sliding member of the embodiment is obtained. The sliding member of the embodiment has a weld mark on the outer peripheral surface of the metal substrate 11, extending from one end of the sliding member 10 in the axial direction to the other end. On the inner peripheral surface behind the weld mark, a region 15 is provided that does not contain resin composition and exposes a non-porous layer 14, extending from one end of the sliding member 10 in the axial direction to the other end. Figure 26 This is a graph showing the inner diameter of the sliding member in the embodiment, obtained by measuring at various angles of 90°, 180°, 270°, and 360° in the circumferential direction. For example... Figure 26 As shown, the inner diameter accuracy of the sliding member in the embodiment is less than 0.018 mm.

[0193] Furthermore, the sliding components of Comparative Examples 1 and 2 were manufactured using the manufacturing process described in Japanese Patent Application No. 2023-026107. Specifically, as Comparative Example 1, a carbon steel round bar was machined into a seamless, thin-walled cylindrical metal substrate with an outer diameter of Φ22mm, an inner diameter of Φ20.62mm, and a total length of 10.35mm using a lathe. As Comparative Example 2, a carbon steel sheet with a length of 67mm, a width of 11mm, and a thickness of 0.75mm was machined into a rolled shape to obtain a cylindrical metal substrate with a seam width of 2mm or less (seam-type).

[0194] Next, for Comparative Example 1, refer to Japanese Patent Application No. 2023-026107. Figure 5 and Figure 6 A. A carbon steel clamp with an outer diameter of 19.96 mm is inserted into a metal substrate with an inner diameter of Φ20.62 mm. Bronze powder, the same as in the example, is added into the 0.3 mm gap between the inner circumferential surface of the metal substrate and the outer circumferential surface of the clamp. Since the inner diameter of the metal substrate is Φ20.6 mm, the outer diameter of the clamp is Φ19.96 mm, and the total length is 10.35 mm, the powder filling volume is 0.21 cm³. 3 Regarding Comparative Example 2, refer to Japanese Patent Application No. 2023-026107. Figure 6B. After pressing the metal substrate into the inside of the housing to seal the joint, a carbon steel clamp is coaxially positioned on the inside of the metal substrate while it is pressed into the housing. Bronze powder, as in the previous example, is fed into a 0.3 mm annular gap between the inner circumferential surface of the metal substrate and the outer circumferential surface of the clamp. In either Example 1 or 2, to ensure good flowability of the powder fed into the gap, a rotating shaft is connected to the clamp, and the clamp is rotated using 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 belt speed of 230 mm / min.

[0195] Next, for Comparative Examples 1 and 2, resin was impregnated into the inner side of a cylindrical metal substrate sintered with bronze powder. The impregnated resin consisted of graphite powder: 1.1% by mass, hard particle powder containing a Laffers phase composed of Co, Mo, and Si: 15% by mass, and the balance being PTFE resin. To improve self-lubricating properties, MoS2 powder: 15% by mass 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 from Nippon Graphite (brand name: CPBW-5). The resin impregnation method was the same as in the above examples, and descriptions are omitted.

[0196] Next, similar to the above embodiment, using an Amsler testing machine, the outer peripheral surface of the metal substrate is constrained by the mold 41 and the mandrel 42 is pressed into the inside of the sliding layer, thereby applying a load to the inner peripheral surface of the sliding layer 13 for correction (polishing).

[0197] Through the above manufacturing process, sliding components of Comparative Examples 1 and 2 are obtained. Figure 27 This is a graph showing the inner diameter of the sliding member of Comparative Example 1 measured at various angles of 90°, 180°, 270°, and 360° in the circumferential direction. For example... Figure 27 As shown, the inner diameter accuracy of the sliding member in the embodiment is less than 0.037 mm. It is speculated that in the powder filling method, such as Comparative Examples 1 and 2, where bronze powder is filled one by one and then sintered, the deviation of the inner diameter is larger compared to the method in the embodiment, where bronze powder is sintered and then shaped into a cylindrical shape.

[0198] In addition, as Comparative Example 3, bronze powder, the same as in Examples 1 and 2, was dispersed on a carbon steel plate material (metal substrate) and sintered to form a porous layer. Next, a resin consisting of 4% by mass of graphite powder, 7.25% by mass of MoS2 powder, and the remainder PTFE resin was impregnated into the porous layer, and the resin was calcined to form a sliding layer covering the porous layer. Then, calendering was performed. Next, the calendered metal substrate was processed into a roll shape with the sliding layer as the inner side, thereby producing a sliding member in which the metal substrate, porous layer, and sliding layer all have a seam (joint).

[0199] Figure 13 This is a table summarizing the composition of the sliding members of the embodiments and comparative examples 1 to 3 made according to the above steps.

[0200] (High-speed rotational wear test)

[0201] Next, the performance of the sliding components of Examples 1-3 and Comparative Examples 1-3 was compared by high-speed rotational wear test. Figure 11 This refers to a high-speed rotary wear testing machine. This machine measures the temperature on the back of the bearing when load and speed are applied to the test material via a mating shaft, and is primarily suitable for evaluating wear and heat generation in high-speed areas. An oil bath is provided in the testing section, designed to perform evaluations in both oil-lubricated and unlubricated environments. Furthermore, to achieve high-speed rotary evaluation, a spindle motor (model S262B-SJ03, rated output 1.2kW, rated voltage 200V, rated current 4.8A) manufactured by Shinsakura Electric Co., Ltd. is directly connected to the top end of a Φ6h7 mating shaft via spring collets. This design enables evaluations up to 60,000 rpm with an accuracy of shaft runout less than 0.002mm. The spindle motor is water-cooled via a cooler at a flow rate of 0.7L / min.

[0202] The outer diameter of the mating shaft is Φ11.957mm~11.975mm, and the inner diameter of the housing is Φ14.000mm~14.018mm. All materials are SKD-11, and the hardness after full quenching is HRC58. Regarding the bearing back temperature, a thermocouple is inserted into a Φ6mm hole, and a data logger is used to measure the temperature at a position 1.5mm from the bearing back every second.

[0203] Next, regarding the test environment, the presence or absence of lubrication of the bearing has a significant impact on its performance. For example, in air conditioning compressor mechanisms such as those used in automotive air conditioning systems, where the rotating scroll is pressed forcefully against a fixed scroll during rotational motion, lubricating oil is difficult to flow into the bearing. Furthermore, in EV drive motors, high-speed rotation is indispensable to achieve a balance between miniaturization, lightweight design, and high output. While oil-lubricated or grease-lubricated bearings are used to support the motor, the simplification of the surrounding structure means that oil lubrication of the bearing portion cannot be fully relied upon. Considering these practical constraints, this test was conducted under an unlubricated environment, measuring frictional heat generation and wear relative to the shaft's rotational speed. Frictional heat generation was evaluated using the bearing temperature rise rate as an indicator, and regression analysis was used to analyze the slope of the temperature relative to the time it takes for the bearing back surface temperature to reach 80°C. Wear was determined by measuring the wall thickness of the sliding component before and after the test using a tubular micrometer and calculating the change in wall thickness at the load point.

[0204] Regarding the shaft speed, the maximum speed is approximately 10,000 rpm for the compressor spindle and approximately 30,000 rpm for the EV motor. Taking this into consideration, a range of 10,000~50,000 rpm is set. Considering the operating limits and safety of the spindle motor at high speeds, a radial load of 10 N is applied to the bearing in one direction. The target clearance between the bearing and the shaft is set to 0.1 mm. Grinding and finishing are performed to achieve a shaft surface roughness of Ra 0.17 μm for testing purposes.

[0205] For the sliding member of the embodiment, a region 15 without resin composition is provided on a portion of the inner circumferential surface, and, as... Figure 12 As shown, the position 90° away from region 15 in the circumferential direction is set as the load point (hereinafter, the position of this load point is referred to as load region A).

[0206] Furthermore, the frictional torque caused by rotational motion can be expressed as follows (1) since power can be converted into electricity.

[0207] E=P=2π·N·T / 60=2π·N·F·R / 60…Equation (1)

[0208] Here, R is the radius of rotation (m), F is the friction force (N), N is the shaft rotation speed (rpm), T is the torque (N·m), E is the electric current (W), and P is the power (W).

[0209] (Results and Investigation)

[0210] Figure 14 The graph shows the time-varying temperature of the bearing backside measured at a shaft speed N = 15000 rpm for the sliding member of Examples 1-3 and Comparative Examples 1-3. Figure 15 This is a graph showing the time-varying temperature of the bearing backside measured at a shaft speed of N = 20000 rpm. Figure 16 This is a graph showing the time-varying temperature of the bearing backside measured at a shaft speed of N = 25000 rpm. Figure 17 This is a graph showing the time-varying temperature of the bearing backside measured at a shaft speed of N = 30000 rpm. Figure 18 This is a graph showing the time-varying temperature of the bearing backside measured at a shaft speed of N=35000rpm.

[0211] like Figures 14-16 As shown, in the high-speed rotation region of shaft speed N = 15000~30000 rpm, the temperature change of the sliding member of the embodiment exhibits the same behavior as the temperature change of the sliding members of Comparative Examples 1 and 2 over time. Therefore, it has been confirmed that in the high-speed rotation region of shaft speed N = 15000~30000 rpm, the sliding member of the embodiment maintains the same function as the sliding members of Comparative Examples 1 and 2 (i.e., the sliding member proposed in Japanese Patent Application No. 2023-026107).

[0212] Moreover, such as Figure 17 and Figure 18 As shown, in the high-speed rotation region with a shaft speed N = 30,000 rpm or higher, the temperature change of the sliding member in the embodiment is more gradual than that of the sliding members in Comparative Examples 1 and 2. Therefore, especially in the high-speed rotation region with a shaft speed N = 30,000 rpm or higher, it was confirmed that the temperature rise of the sliding member in the embodiment was suppressed compared to the sliding parts of Comparative Examples 1 and 2 (i.e., the sliding member proposed in Japanese Patent Application No. 2023-026107).

[0213] Figure 19 The graph shows the change in temperature rise rate relative to shaft speed within the range of 10,000 to 50,000 rpm for the sliding member of the embodiments and comparative examples 1 to 3. Figure 20 It is a graph showing the change in power consumption relative to shaft speed within this range.

[0214] like Figure 19 and Figure 20 As shown, the shaft speed at which a sharp increase in temperature rise rate and power consumption occurs is 15,000 rpm in the sliding member of Comparative Example 3, 25,000 rpm in the sliding member of Comparative Example 2, and 30,000 rpm in the sliding member of Comparative Example 1. In contrast, it is 35,000 rpm in the sliding member of the embodiment. Therefore, it is confirmed that the permissible limit speed of the sliding member of the embodiment is higher than that of the sliding members of Comparative Examples 1 to 3.

[0215] Furthermore, additional evaluation tests were conducted by subtly altering the rotational speed in the vicinity of the shaft speed where a sharp increase in temperature rise rate and power consumption occurred. Figure 21 The graph shows the change in the rate of temperature rise relative to the shaft speed in a range near the shaft speed where a sharp increase in the rate of temperature rise and power consumption occurs, for the sliding member of Embodiments and Comparative Examples 1-3. Figure 22 It is a graph showing the change in power consumption relative to shaft speed within this range.

[0216] like Figure 21 and Figure 22 As shown, in Comparative Example 3, the sliding member exhibits a relatively constant rate of temperature rise and power consumption within the shaft speed range of 7000~8000 rpm, but rises sharply above 8000 rpm. Therefore, the permissible speed limit can be determined to be 8000±1000 rpm. Similarly, in Comparative Example 2, the sliding member exhibits a relatively constant rate of temperature rise and power consumption within the shaft speed range of 22000~25000 rpm, but rises sharply above 25000 rpm. Therefore, the permissible speed limit can be determined to be 23500±1500 rpm. Furthermore, in Comparative Example 1, the sliding member exhibits a relatively constant rate of temperature rise and power consumption within the shaft speed range of 27000~30000 rpm, but rises sharply above 30000 rpm. Therefore, the permissible speed limit can be determined to be 28500±1500 rpm. In contrast, the sliding component of the embodiment has a relatively constant temperature rise rate and power consumption within the shaft speed range of 30,000 to 33,000 rpm, but rises sharply when it exceeds 33,000 rpm. Therefore, it can be determined that the allowable limit speed is 31,500 ± 1,500 rpm.

[0217] Next, regarding the effect of suppressing temperature rise, in order to investigate the influence of the region 15 on the inner circumferential surface where no resin composition is present, for the sliding member of the embodiment, such as... Figure 23 As shown, an additional evaluation test was conducted with the load point located at the position consistent with the circumferential direction of region 15 (hereinafter, the position of the load point is referred to as load region B).

[0218] Figure 25 This is a graph showing the change in the rate of temperature rise relative to the shaft rotation speed, measured in load region A and load region B respectively for the sliding member in the embodiment. Figure 26 It is a graph showing the change in power consumption relative to shaft speed.

[0219] like Figure 25 and Figure 26As shown, within the shaft speed range of 30,000 to 33,000 rpm, the temperature rise rate and power consumption changes in load region A and load region B are approximately the same. However, in the range above 33,000 rpm, both the temperature rise rate and power consumption in load region A increase compared to load region B. It is speculated that in load region A, the temperature rises due to the accumulation of frictional heat at the contact points. Conversely, in load region B, the frictional heat at the contact points is mitigated by the absence of grooves in region 15 containing the resin composition, making heat dissipation easier and thus suppressing the temperature rise.

[0220] The embodiments and modifications have been described above by way of example, but the scope of this technology is not limited thereto, and modifications and variations can be made according to the purpose within the scope of the claims. In addition, the various embodiments and modifications can be appropriately combined without contradicting the content of the solution.

Claims

1. A sliding member, characterized in that, It possesses: Cylindrical metal substrate A 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 from a metallic element or an alloy composition. The sliding layer is formed of a resin composition. The sliding member has a region on its inner circumferential surface where the resin composition is absent and a non-porous layer formed of the elemental metal or alloy composition is exposed.

2. The sliding member according to claim 1, characterized in that, The region is configured to extend from one end of the sliding member along its axial direction to the other end.

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

4. The sliding member according to claim 3, characterized in that, The sliding layer further disperses at least one of MoS2 powder and bronze powder without Laffers phase.

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

6. The sliding member according to claim 1 or 2, characterized in that, The porous layer has the following characteristics: The matrix phase comprises Cu and Sn; and Hard particles, dispersed in the matrix phase, comprising a Lafferse phase consisting of Co, Mo and Si.

7. The sliding member according to claim 6, characterized in that, The porous layer further has: The compound phase, which is dispersed in the matrix phase, comprises 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. A bearing, characterized in that, It possesses: Cylindrical metal substrate A 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 from a metallic element or an alloy composition. The sliding layer is formed of a resin composition. The bearing has a region on its inner circumferential surface where the resin composition is absent and a non-porous layer formed of the elemental metal or alloy composition is exposed.

10. A method for manufacturing a sliding component, characterized in that, It includes: The step of forming a porous layer composed of a metallic element or alloy composition on one side of a metal substrate; The step of rolling up the metal substrate with the porous layer as the inside to form a cylindrical shape; The step of welding the joint portion from the outer diameter side of the metal substrate, wherein the porous layer on the joint portion melts to form a non-porous layer formed of the elemental metal or alloy composition; and, The step of impregnating the surface of the porous layer with the raw resin of the sliding layer and calcining the raw resin to form a sliding layer composed of a resin composition covering the porous layer, wherein, since the surface of the non-porous layer is not impregnated with the raw resin, a region is formed on a portion of the inner circumferential surface of the sliding member where the resin composition is absent and the non-porous layer is exposed.

11. A method for manufacturing a sliding component, characterized in that, It includes: The step of forming a porous layer composed of a metallic element or alloy composition on one side of a metal substrate; The step of impregnating the surface of the porous layer with the raw material resin of the sliding layer and calcining the raw material resin to form a sliding layer composed of a resin composition covering the porous layer; The step of rolling up the metal substrate with the sliding layer as the inside to form a cylindrical shape; as well as, The step of welding the joint portion from the outer diameter side of the metal substrate, wherein the porous layer on the joint portion melts to form a non-porous layer formed of the metal element or alloy composition, and the sliding layer on the joint portion peels off, thereby forming a region on a portion of the inner circumferential surface of the sliding member where the resin composition is absent and the non-porous layer is exposed.

12. The method according to claim 10 or 11, characterized in that, It further includes the following steps: The outer peripheral surface of the metal substrate is constrained by a mold, and a cylindrical mandrel is pressed into the inner side of the sliding layer, thereby polishing the inner peripheral surface of the sliding layer.

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