A hydraulic cylinder support ring and a preparation method thereof

Abstract

The invention relates to a hydraulic cylinder support ring, comprising an inner ring and an outer ring which are coaxially sleeved; the inner ring is a first powder sintered body; the first powder sintered body is formed by hot pressing and sintering a first powder composition, the first powder composition comprising: 100 parts of iron powder, 20-23 parts of electrolytic copper powder, 0.5-1 parts of graphite powder, 2-3 parts of tungsten carbide powder, 3-4 parts of transition metal disulfide powder, and 2-3 parts of zinc stearate; the outer ring is a second powder sintered body; the first powder sintered body is formed by hot pressing and sintering the first powder composition, the second powder composition comprising: 100 parts of polytetrafluoroethylene powder, 1-1.5 parts of carbon fiber powder, 1-2 parts of transition metal disulfide, and 10-15 parts of bronze powder.

Description

Technical Field

[0001] The invention belongs to the field of engineering machinery, and in particular relates to a hydraulic cylinder support ring and a preparation method thereof. Background Art

[0002] Hydraulic cylinder is an energy conversion device that converts hydraulic energy into mechanical energy and is an actuator of hydraulic transmission system. It is widely used in engineering machinery due to its simple structure, high working reliability and stable transmission.

[0003] Support rings, also known as support rings and guide belts, are usually installed at the piston seals and piston rod seals of hydraulic cylinders. Their main function is to guide the piston and piston rod to make linear motion, to prevent the piston and piston rod from being over-extruded due to eccentric loading, resulting in rapid failure of the seal and causing hydraulic oil leakage.

[0004] Figure 1 A schematic diagram of a hydraulic cylinder is shown. The support ring 1 can be installed on the cylinder piston 2 to prevent contact friction and wear between the piston 2 and the cylinder barrel 3 during movement. The support ring 1 can be installed on the guide sleeve 4 to prevent contact friction and wear between the piston rod 5 and the guide sleeve 4 during movement. The support ring 1 can also absorb the radial load force F acting on the hydraulic cylinder to ensure the movement accuracy of the hydraulic cylinder. When the cylinder is operating, the support ring 1 and the cylinder barrel 3 and the piston rod 5 produce sliding friction and wear. Under the action of the radial load force F, the support ring 1 is subjected to increased force and the sliding friction force becomes larger, which can easily cause the cylinder to shake and creep, affecting the movement accuracy of the cylinder.

[0005] Polytetrafluoroethylene is a polymer made from tetrafluoroethylene as a monomer, referred to as PTFE. Polytetrafluoroethylene material has excellent acid and alkali resistance, oil resistance, aging resistance, high and low temperature resistance and extremely low friction coefficient, making it an ideal material for sealing. However, due to the low hardness and mechanical strength of pure polytetrafluoroethylene, it will produce large viscoelastic deformation under the action of external forces, and is prone to creep, etc., which limits the application of polytetrafluoroethylene under high load conditions. Summary of the invention

[0006] The inventor found that in order to make up for the shortcomings of PTFE's mechanical properties, the existing technology mostly uses fillers for modification. The invention patent "High-load and low-friction coefficient polytetrafluoroethylene friction material and its manufacturing process" with application number 201110142142.8 uses polyphenyl parahydroxybenzoate, expanded graphite, basalt fiber, etc. to modify polytetrafluoroethylene, and obtains a high-load and low-friction coefficient polytetrafluoroethylene material, which has obvious improvements in tensile strength, ball indentation hardness, wear resistance, etc., and can meet the demanding application requirements in industrial and transportation fields such as railway freight car bogies and sliding slewing bearings. The content of polytetrafluoroethylene in this invention patent is 64.95%-93.99%, which is a continuous phase in the material. Although the basalt fiber, expanded graphite and other materials used in the formula have a certain anti-creep effect, long-term high-load conditions will accelerate the creep process of the material and cause material failure.

[0007] The invention patent with application number 200510095700.4, "High wear-resistant polytetrafluoroethylene composite material and its preparation method", uses polyacrylonitrile powder, non-metallic oxides, metal oxides and other fillers to fill polytetrafluoroethylene to obtain a modified material with good wear resistance, low friction coefficient and high temperature resistance. Although the powder filler used in this patent can effectively improve the wear resistance of polytetrafluoroethylene, it does not improve the mechanical strength and load-bearing performance of polytetrafluoroethylene and is not suitable for high-load working conditions.

[0008] The invention patent "A Steel-lined Polytetrafluoroethylene Sealing Body" with application number 201721371332.6 proposes a sealing body composed of a metal shell and polytetrafluoroethylene on the inner side, wherein the polytetrafluoroethylene is composed of a metal mesh layer, a polytetrafluoroethylene outer layer, a metal wire winding layer, a polytetrafluoroethylene film layer, etc., and the difference in thermal expansion coefficients between polytetrafluoroethylene and metal is avoided through various means, thereby improving its ability to withstand negative pressure. The patent uses a metal mesh layer, a winding layer, a film layer and other multi-layer materials to composite, which can improve its compressive strength to a certain extent, but the preparation process of this method is complicated, and there are multiple interfaces where dissimilar materials interact with each other, and the interface bonding effect is difficult to guarantee.

[0009] In the above cases, although the load-bearing performance of PTFE has been improved through formula modification or steel wire reinforcement, the nature of PTFE itself that is prone to creep has not changed. After a long time, it will still creep under high load, leading to extrusion failure and reducing its service life.

[0010] In order to solve the problems of low mechanical strength, poor bearing capacity, easy creep, and complex preparation process of polytetrafluoroethylene in the prior art, the present invention provides a high-load polytetrafluoroethylene oil cylinder support ring with an inner layer, which improves the mechanical strength, bearing strength and creep resistance of the polytetrafluoroethylene support ring through material component design and overall structural design, optimizes the preparation process by using integrated sintering technology, solves the problem of poor interface bonding effect between the inner layer and the outer grinding layer, and finally achieves an increase in service life. The technical solution is as follows:

[0011] In a first aspect, the present application provides a hydraulic cylinder support ring, comprising an inner ring and an outer ring coaxially sleeved

[0012] The inner ring is a first powder sintered body;

[0013] The first powder sintered body is formed by hot pressing and sintering a first powder composition, wherein the first powder composition comprises: 100 parts of iron powder, 20-23 parts of electrolytic copper powder, 0.5-1 parts of graphite powder, 2-3 parts of tungsten carbide powder, 3-4 parts of transition metal disulfide powder, and 2-3 parts of zinc stearate;

[0014] The outer ring is a second powder sintered body;

[0015] The second powder sintered body is formed by hot pressing and sintering a second powder composition, wherein the second powder composition comprises: 100 parts of polytetrafluoroethylene powder, 1-1.5 parts of carbon fiber powder, 1-2 parts of transition metal disulfide, and 10-15 parts of bronze powder.

[0016] In the above embodiment, the hydraulic cylinder support ring has an innovative multilayer structure. The inner layer of the specific composition has improved compressive strength, the outer layer of the specific composition has improved wear resistance, and the innovative multilayer structure has the advantages of high mechanical strength, large load-bearing capacity, low creep, and simple preparation process.

[0017] In the above scheme, the role of iron powder includes improving the strength of the material and enhancing the compression resistance of the support ring; the role of graphite powder includes strengthening the mechanical properties of the metal and improving the self-lubricating effect of the support ring; the role of copper powder includes optimizing the thermal conductivity, promoting the sintering process, and improving the friction performance; the role of tungsten carbide powder includes forming a hard and wear-resistant material during the sintering process and improving the strength and rigidity of the support ring; the role of transition metal tungsten disulfide powder includes providing friction reduction and anti-wear effects; the role of zinc stearate includes reducing the friction between powder particles and between powder particles and the mold, and improving the fluidity of the powder.

[0018] In some embodiments, the first powder composition includes: 100 parts of iron powder, 20-23 parts of electrolytic copper powder, 0.7-0.8 parts of graphite powder, 2.0-2.3 parts of tungsten carbide powder, 3.0-3.5 parts of transition metal disulfide powder, and 2-3 parts (e.g., 2.5 parts) of zinc stearate;

[0019] In some embodiments, the first powder sintered body is formed by hot pressing and sintering a first powder composition, and the second powder composition includes: 100 parts of polytetrafluoroethylene powder, 1-1.5 parts of carbon fiber powder, 1.5-2 parts of transition metal disulfide, and 10-15 parts of bronze powder.

[0020] In some embodiments, the transition metal disulfide powder is selected from one or more of molybdenum disulfide powder and tungsten disulfide powder.

[0021] In some embodiments, the radially outward surface of the inner ring has a first concave-convex structure, and the radially inward surface of the outer ring has a second concave-convex structure, and the first concave-convex structure and the second concave-convex structure are interlocked. The above concave-convex structure further improves the bonding strength between the inner layer and the outer layer.

[0022] In some embodiments, the first concavo-convex structure includes a protrusion or a groove extending in the axial direction of the hydraulic cylinder support ring.

[0023] In some embodiments, the second concavo-convex structure includes a protrusion or a groove extending in the axial direction of the hydraulic cylinder support ring.

[0024] In some embodiments, the height of the protrusion on the inner ring is 1 / 3-2 / 3 of the total wall thickness of the inner ring.

[0025] In some embodiments, the depth of the groove on the inner ring is 1 / 3-2 / 3 of the total wall thickness of the inner ring.

[0026] In some embodiments, the height of the protrusion on the outer ring is 1 / 3-2 / 3 of the total wall thickness of the inner ring.

[0027] In some embodiments, the depth of the groove on the outer ring is 1 / 3-2 / 3 of the total wall thickness of the inner ring.

[0028] In some embodiments, a silicone resin bonding layer is provided between the inner ring and the outer ring.

[0029] In some embodiments, the hydraulic cylinder support ring is composed of a plurality of arc-shaped bodies.

[0030] In some embodiments, the wall thickness of the inner ring is 1.0-1.5 mm.

[0031] In some embodiments, the wall thickness of the outer ring is 1.5-2.0 mm.

[0032] In some embodiments, the wall thickness ratio of the inner ring to the outer ring is 0.5-1:1.

[0033] In some embodiments, the total thickness of the hydraulic cylinder support ring is 2.5-3.5 mm.

[0034] In some embodiments, the inner diameter of the hydraulic cylinder support ring is 50-500 mm.

[0035] In a second aspect, the present application provides a method for preparing the hydraulic cylinder support ring, comprising:

[0036] (1) 100 parts of iron powder, 20-23 parts of electrolytic copper powder, 0.5-1 parts of graphite powder, 2-3 parts of tungsten carbide powder, 3-4 parts of transition metal disulfide powder, and 2-3 parts of zinc stearate;

[0037] (2) placing the first powder composition in a first mold and performing a first hot pressing sintering to form an inner ring;

[0038] (3) providing a second powder composition comprising: the first powder sintered body is formed by hot pressing and sintering the first powder composition, and the second powder composition comprises: 100 parts of polytetrafluoroethylene powder, 1-1.5 parts of carbon fiber powder, 1-2 parts of transition metal disulfide, and 10-15 parts of bronze powder;

[0039] (4) placing the inner ring obtained in step (2) and the second powder composition in a second mold for a second hot pressing sintering to form an outer ring on the outer side of the inner ring to be sleeved with the inner ring.

[0040] In some embodiments, step (2) further comprises applying a silicone resin adhesive to the radially outward surface of the inner ring.

[0041] In some embodiments, the temperature of the first sintering is 1080-1180°C;

[0042] In some embodiments, the first sintering time is 1-2 hours.

[0043] In some embodiments, the temperature of the second sintering is 350-400°C;

[0044] In some embodiments, the second sintering time is 2-5 hours.

[0045] In some embodiments, the hydraulic cylinder is a hydraulic ram or a hydraulic air cylinder.

[0046] Terminology

[0047] The term "support ring" refers to a part used on the piston or guide sleeve of a hydraulic cylinder or air cylinder to support the movement of the piston or piston rod. It can prevent the piston or piston rod from direct contact and friction with the cylinder body during movement, thereby protecting the cylinder body and the piston or piston rod from damage.

[0048] The term "powder sintering" refers to the process of heating a powder compact to a specified temperature and keeping it at that temperature for a period of time, so that physical and chemical reactions such as atomic diffusion, solid solution, chemical combination and welding occur between the powder particles, so that the compact shrinks, densifies and strengthens, and finally obtains certain physical and mechanical properties. The product obtained by powder sintering is a powder sintered body.

[0049] The raw materials for powder sintering can be selected from one or more of metal powder, ceramic powder and polymer powder.

[0050] Unless otherwise specified, % refers to mass %.

[0051] Beneficial Effects of the Invention

[0052] One or more embodiments of the present invention have one or more of the following beneficial effects:

[0053] (1) The hydraulic cylinder support ring has an innovative structure;

[0054] (2) The hydraulic cylinder support ring has improved hardness;

[0055] (3) The hydraulic cylinder support ring has improved compressive strength;

[0056] (4) The hydraulic cylinder support ring has an improved cycle life; BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute a limitation of the present invention. In the drawings:

[0058] Figure 1 is a schematic diagram of a hydraulic cylinder of some embodiments;

[0059] Figure 2 Schematic diagram of a hydraulic cylinder support ring of some embodiments;

[0060] Figure 3 It is a partial schematic diagram of a hydraulic cylinder support ring of some embodiments;

[0061] Figure 4 Schematic diagrams of hydraulic cylinder support rings according to some further embodiments.

[0062] Figure 5 Schematic diagrams of hydraulic cylinder support rings according to some further embodiments. DETAILED DESCRIPTION

[0063] Specific embodiments of the present invention will now be mentioned in detail. Examples of specific embodiments are illustrated in the accompanying drawings. Although the present invention is described in conjunction with these specific embodiments, it should be appreciated that it is not intended to limit the present invention to these specific embodiments. On the contrary, these embodiments are intended to cover substitutions, changes or equivalent embodiments that may be included in the spirit and scope of the invention defined by the claims. In the following description, a large number of specific details are set forth in order to provide a comprehensive understanding of the present invention. The present invention may be implemented without some or all of these specific details. In other cases, in order not to make the present invention unnecessarily obscure, well-known process operations are not described in detail.

[0064] To further illustrate the present invention, a hydraulic cylinder support ring provided by the present invention is described in detail below in conjunction with the accompanying drawings and embodiments, but it should not be understood as limiting the protection scope of the present invention.

[0065] The following examples and comparative examples are used to prepare support ring products with dimensions of 1.5 mm inner diameter, 1.5 mm outer diameter, and 25 mm axial length.

[0066] In the following examples and comparative examples, the first powder composition formula is 22 parts of electrolytic copper powder, 0.8 parts of graphite, 2.0 parts of tungsten carbide, 2.5 parts of molybdenum disulfide, 0.5 parts of tungsten disulfide, and 100 parts of iron powder.

[0067] In the following examples and comparative examples, there are 100 parts of tetrafluoroethylene powder, 1.5 parts of carbon fiber powder, 1.3 parts of molybdenum disulfide, 0.2 parts of tungsten disulfide, and 13 parts of bronze powder.

[0068] Example 1

[0069] This embodiment provides a hydraulic cylinder support ring. Figure 2 Figure 1 is a schematic diagram of the hydraulic cylinder support ring. Figure 2 As shown, the supporting ring comprises an inner layer 10 and an outer layer 20, and the inner layer 10 and the outer layer 20 are coaxially sleeved together.

[0070] Figure 3 A partial schematic diagram of the support ring is shown. As shown in the figure, a first concave-convex structure 11 is provided on the radially outward surface of the inner layer 10, and a second concave-convex structure 21 is provided on the radially inward surface of the outer layer 20, and the first concave-convex structure 11 and the second concave-convex structure 21 are embedded with each other. The thickness D1 of the inner layer 10 is equal to the thickness D2 of the outer layer 20, both of which are 0.75 mm.

[0071] The preparation method of the support ring is as follows:

[0072] (1) placing the first powder composition in a mold and hot pressing and sintering at 1130° C. for 1.5 h to obtain an inner layer;

[0073] (2) Five grooves are machined on the radially outward surface of the inner layer, and the depth of the grooves is 1 / 2 of the thickness of the inner layer;

[0074] (3) Apply 0.5 mm thick silicone resin adhesive in the groove;

[0075] (4) using the inner layer as a core mold and a cylinder coaxial with the core mold as an outer mold, filling a second powder composition between the inner mold and the outer mold, compacting the powder, and removing the outer mold to obtain a preform;

[0076] (5) The prefabricated blank is placed in a sintering furnace, heated at 380°C for 3 hours, and cooled out of the furnace to obtain a support ring product.

[0077] Example 2

[0078] This embodiment provides a support ring. Figure 4 As shown, the support ring includes a first arc-shaped body 51 and a second arc-shaped body 52. ​​The first arc-shaped body 51 and the second arc-shaped body 52 are semicircular arc-shaped bodies respectively, and the two are embedded with each other to form a complete support ring.

[0079] Referring to the method of Example 1, the first arc-shaped body 51 and the second arc-shaped body 52 are prepared respectively, and then the first arc-shaped body 51 and the second arc-shaped body 52 are assembled to obtain the support ring of Example 2.

[0080] Example 3

[0081] This embodiment provides a support ring. Figure 5 As shown, the support ring includes an inner layer 10 and an outer layer 20, which are coaxially sleeved together. The radially outward surface of the inner layer 10 is a smooth surface (without concavo-convex structure) and the radially inward surface of the outer layer 20 is a smooth surface (without concavo-convex structure).

[0082] The method for preparing the support ring of this embodiment refers to that of Embodiment 1, except that step (2) is not performed.

[0083] Comparative Example 1

[0084] This embodiment provides a support ring. The support ring is a single-layer structure and is homogeneous as a whole.

[0085] (1) Filling polytetrafluoroethylene powder into a hollow cylindrical mold;

[0086] (2) compacting the mixed powder with a certain pressure to form a support ring preform;

[0087] (3) The blank is placed in a high temperature furnace and kept at 380°C for 3 h to obtain a pure polytetrafluoroethylene support ring product.

[0088] Comparative Example 2

[0089] This embodiment provides a support ring. The support ring is a single-layer structure and is homogeneous as a whole.

[0090] (1) filling a second powder composition into a hollow cylindrical mold;

[0091] (2) compacting the mixed powder with a certain pressure to form a support ring preform;

[0092] (3) The blank is placed in a high-temperature furnace and kept at 380° C. for 3 h to obtain a modified polytetrafluoroethylene support ring product.

[0093] Analysis and testing

[0094] The present invention tests the installation effect, tensile strength, hardness, load-bearing performance, creep resistance and service life of the support rings prepared in the examples and comparative examples. The test results are shown in Table 1.

[0095] Table 1 Performance test results of support rings prepared in the embodiments of the present invention and the comparative examples

[0096]

[0097] The performance of the supporting rings of the embodiments and comparative examples are analyzed below in conjunction with Table 1:

[0098] (1) Installation effect

[0099] The support rings of Examples 1-3 and Comparative Examples 1-2 can be adaptively installed on the hydraulic cylinder, and the installation effects are excellent.

[0100] (2) Tensile strength

[0101] According to GB / T1040-2018, the tensile strength of Comparative Examples 1 and 2 was tested, and the results showed that the strength of Comparative Example 2 after formula optimization was significantly higher than that of the unmodified Comparative Example 1. The tensile strength values ​​of Examples 1, 2 and 3 could not be measured due to the inner lining.

[0102] (3) Hardness

[0103] According to the test of GB / T2411-2008, the support rings of Examples 1-3 contain an inner layer, and the hardness value is higher than that of Comparative Examples 1 and 2.

[0104] (4) Compression strength

[0105] According to GB / T1041-2008, at a strain value of 10%, the compressive strength of Examples 1-3 is much higher than that of Comparative Examples 1 and 2, indicating that the design of the powder metallurgy lining structure can effectively improve the compressive strength of the polytetrafluoroethylene support ring; the compressive strength of Comparative Example 2 is 2.4 times that of Comparative Example 1, indicating that the filling material used in this patent can improve the compressive performance of the polytetrafluoroethylene body.

[0106] (5) Creep resistance and service life

[0107] The above-mentioned support ring was tested using a high-temperature reciprocating accelerated life tester for cylinder seals (self-made). The reciprocating speed was set to 200 mm / s, and the eccentric load force was set to 2000 N, to test the creep resistance and service life of the support ring. The results showed that: Examples 1 and 2 did not fail for more than 5000 hours, and the outer and inner layers of polytetrafluoroethylene were well bonded and there was no delamination; Example 3 failed at 3000 hours. The support ring of Comparative Example 1 failed after 200 hours; the support ring of Comparative Example 2 failed at 1800 hours. In addition, through the analysis of failed samples, it was found that Comparative Examples 1 and 2 were both extrusion failure modes caused by creep of the polytetrafluoroethylene body under high load.

[0108] Through the test analysis, it can be seen that Examples 1-3 have the advantages of high hardness, high compression strength, excellent creep resistance, and long service life, and can solve the shortcomings of the prior art. Among them, Examples 1-2 are all more than 5000 hours without failure, and the polytetrafluoroethylene outer layer and the inner layer are well bonded and there is no delamination.

[0109] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A hydraulic cylinder support ring, comprising an inner ring and an outer ring coaxially sleeved; The inner ring is a first powder sintered body; The first powder sintered body is formed by hot pressing and sintering a first powder composition, wherein the first powder composition comprises: 100 parts of iron powder, 20-23 parts of electrolytic copper powder, 0.5-1 parts of graphite powder, 2-3 parts of tungsten carbide powder, 3-4 parts of transition metal disulfide powder, 2-3 parts of zinc stearate; The outer ring is a second powder sintered body; The second powder sintered body is formed by hot pressing and sintering a second powder composition, wherein the second powder composition comprises: 100 parts of polytetrafluoroethylene powder, 1-1.5 parts of carbon fiber powder, 1-2 parts of transition metal disulfide, and 10-15 parts of bronze powder. A silicone resin bonding layer is provided between the inner ring and the outer ring.

2. The hydraulic cylinder support ring according to claim 1, wherein: The transition metal disulfide powder is selected from one or more of molybdenum disulfide powder and tungsten disulfide powder.

3. The hydraulic cylinder support ring according to claim 1, wherein: The radially outward surface of the inner ring has a first concave-convex structure, and the radially inward surface of the outer ring has a second concave-convex structure, and the first concave-convex structure and the second concave-convex structure are embedded in each other.

4. The hydraulic cylinder support ring according to claim 3, having one or more of the following features: - the first concavo-convex structure comprises a protrusion or a groove extending in the axial direction of the hydraulic cylinder support ring; The second concavo-convex structure comprises protrusions or grooves extending in the axial direction of the hydraulic cylinder support ring.

5. The hydraulic cylinder support ring according to claim 4, having one or more of the following features: -The height of the protrusion on the inner ring is 1 / 3-2 / 3 of the total wall thickness of the inner ring; -The depth of the groove on the inner ring is 1 / 3-2 / 3 of the total wall thickness of the inner ring; -The height of the protrusion on the outer ring is 1 / 3-2 / 3 of the total wall thickness of the inner ring; -The depth of the groove on the outer ring is 1 / 3-2 / 3 of the total wall thickness of the inner ring.

6. The hydraulic cylinder support ring according to claim 1, wherein: The hydraulic cylinder supporting ring is composed of a plurality of arc-shaped bodies.

7. The hydraulic cylinder support ring according to claim 1, having one or more of the following features: - the wall thickness of the inner ring is 1.0-1.5 mm; - the wall thickness of the outer ring is 1.5-2.0 mm; - The wall thickness ratio of the inner ring to the outer ring is 0.5-1:

1.

8. The hydraulic cylinder support ring according to claim 1, having one or more of the following features: - The total thickness of the hydraulic cylinder support ring is 2.5-3.5 mm; - The inner diameter of the hydraulic cylinder support ring is 50-500 mm.

9. The method for preparing the hydraulic cylinder support ring according to any one of claims 1 to 8, comprising: (1) providing a first powder composition, wherein the first powder composition comprises: 100 parts of iron powder, 20-23 parts of electrolytic copper powder, 0.5-1 parts of graphite powder, 2-3 parts of tungsten carbide powder, 3-4 parts of transition metal disulfide powder, and 2-3 parts of zinc stearate; (2) placing the first powder composition in a first mold and performing a first hot pressing sintering to form an inner ring; (3) providing a second powder composition, wherein the second powder composition comprises: 100 parts of polytetrafluoroethylene powder, 1-1.5 parts of carbon fiber powder, 1-2 parts of transition metal disulfide, and 10-15 parts of bronze powder; (4) placing the inner ring obtained in step (2) and the second powder composition in a second mold for a second hot pressing sintering, and forming an outer ring on the outer side of the inner ring to be sleeved with the inner ring. The step (2) also includes applying a silicone resin adhesive to the radially outward surface of the inner ring.

10. The method according to claim 9, having one or more of the following features: - The temperature of the first sintering is 1080-1180°C; -The first sintering time is 1-2h.

11. The method according to claim 9, having one or more of the following features: - The temperature of the second sintering is 350-400°C; -The second sintering time is 2-5 h.

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