A sliding bearing with a high molecular coating and a method for producing the same

Abstract

The application relates to a sliding bearing with a high-molecular coating and a preparation method thereof, and belongs to the technical field of sliding members. The sliding bearing comprises a shaft base body, a sliding metal layer and a high-molecular material layer. The sliding metal layer is attached to the circumferential surface of the shaft base body. The surface of the sliding metal layer is in a shaped curved surface shape to adapt to the deformation under the load in the use state. The high-molecular material layer is attached to the surface of the sliding metal layer. The high-molecular material layer comprises a first material layer and a second material layer. The wear resistance of the first material layer is higher than that of the second material layer. The surface of the sliding metal layer is shaped to adapt to the deformation under the load in the use state. Meanwhile, the high-molecular material layer is arranged on the sliding metal layer. The whole high-molecular material layer can realize good self-adaptive shaping, can make up for the problem that the shaping precision of the surface of the sliding metal layer is not enough, can further reduce the friction between the sliding bearing and the corresponding sliding pair, can improve the maximum load that can be borne, and can further reduce the possibility of temperature rise failure.

Description

Technical Field

[0001] This application relates to the field of sliding component technology, and more specifically, to a sliding bearing with a polymer coating and a method for preparing the same. Background Technology

[0002] Clean and environmentally friendly wind power utilizes wind energy to rotate large blades, which in turn rotate the main shaft of the wind turbine, thereby driving the generator to convert kinetic energy into electrical energy. Between the blades and the generator, a speed-increasing transmission device, such as a gearbox, is usually needed to increase the rotational speed. Therefore, bearings are required between the relatively moving planetary gears and planetary shafts in the gearbox to provide support, reduce friction, and reduce wear, thereby ensuring the long-term operation of the gearbox.

[0003] Existing wind turbines mostly use rolling bearings between the planetary gears and the planetary shaft. However, because the blades of wind turbines are subjected to winds of varying sizes and directions, these rolling bearings are usually expensive to manufacture and maintain, and replacement costs are high in order to ensure the long-term reliable operation of the wind turbine.

[0004] Some have proposed using sliding bearings to replace the rolling bearings in current wind turbine gearboxes to improve the above problems, but sliding bearings are more prone to temperature rise failure. Summary of the Invention

[0005] This application provides a sliding bearing with a polymer coating and its preparation method, which can improve the problem of temperature rise failure when the sliding bearing is used as the sliding component of the wind turbine gearbox.

[0006] The inventors discovered that current sliding bearings generally consist of a shaft base and a sliding metal layer. Under load, the pin of the sliding bearing will deform. To accommodate this deformation, the copper alloy surface of the sliding bearing can be modified to withstand a larger maximum operating load. However, even after very high-precision modification, the sliding bearing still cannot adapt to the huge load caused by the frequent start-stop of wind power generation and still has the problem of easy temperature rise failure. The inventors believe that the reason may be that there are certain differences between the theoretical design of the modification, the actual working conditions, and the actual machining accuracy, so it is difficult to achieve the ideal state of modification.

[0007] In a first aspect, embodiments of this application provide a sliding bearing with a polymer coating, the sliding bearing comprising:

[0008] Shaft base;

[0009] The sliding metal layer is attached to the circumferential surface of the shaft base. The surface of the sliding metal layer is a modified curved surface to adapt to deformation under the load of the service condition.

[0010] A polymer material layer is attached to the surface of the sliding metal layer. The polymer material layer includes a first material layer and a second material layer. Along the extension direction of the shaft matrix, the first material layer is attached to the middle of the sliding metal layer, and the second material layer is attached to both ends of the sliding metal layer. The wear resistance of the first material layer is higher than that of the second material layer.

[0011] In the above implementation process, by modifying the surface of the sliding metal layer to adapt to deformation under operating loads, the friction between the sliding bearing and the corresponding sliding pair caused by deformation can be reduced, thereby increasing the maximum operating load that can be withstood and reducing the possibility of temperature rise failure when applied to wind turbine gearboxes. Simultaneously, a polymer material layer is set on the sliding metal layer. This polymer material layer includes a first material layer and a second material layer with different wear resistance. The second material layer with lower wear resistance is set at the end with larger deformation, while the first material layer with higher wear resistance is set at the middle part with smaller deformation. This allows the entire polymer material layer to achieve better self-adaptive modification, compensating for the insufficient modification accuracy of the sliding metal layer surface, further reducing friction between the sliding bearing and the corresponding sliding pair, increasing the maximum operating load that can be withstood, and further reducing the possibility of temperature rise failure.

[0012] As an alternative implementation, the wear resistance of the first material layer is 3 to 6 times that of the second material layer.

[0013] In the above implementation process, by controlling the ratio of the wear resistance of the first material layer to the wear resistance of the second material layer, the entire polymer material layer can adapt to the shape better and faster, so that it can withstand greater operating loads when used as a wind turbine gearbox.

[0014] As an optional implementation, wear resistance is tested using a load rotation test. The test conditions for the load rotation test include: oil lubrication with a viscosity of 320 Pa·s, a unit load of 14 MPa, and a rotational linear speed of 1.2 m / s.

[0015] As an optional implementation, the length of the first material layer is 20% to 40% of the length of the second material layer along the extension direction of the shaft base.

[0016] In the above implementation process, by controlling the length ratio of the first material layer and the second material layer, it is equivalent to controlling the coating position of the first material layer and the second material layer, which can better match the shaping surface of the sliding metal layer. The second material layer with lower wear resistance is filled in the concave area of ​​the shaping to achieve faster and better adaptive shaping.

[0017] As an optional implementation, the thickness of the polymer material layer is 10–30 μm.

[0018] In the above implementation process, by controlling the thickness of the polymer material layer to 10-30 μm, the thickness wear requirements of self-repairing can be met, while also taking into account the curing effect of the polymer material layer, so that the performance of the polymer material layer can be repeatedly exerted.

[0019] As an optional implementation, the polymer material layer comprises at least one of the following: polyimide polymer, polyamide-imide polymer, polyimide, polysuccinimide, polybismaleimide, polybenzimidazole, polyoxadiazole-benzimidazole, polyimide sulfone, polyurethane, polyester, polyphenylene sulfide, fluoropolymer, polyetheretherketone, alkyd resin, polyacrylate, epoxy resin, phenolic resin, and silicone resin.

[0020] As an alternative implementation, the polymer material layer may also include at least one of graphite, carbon nanotubes, polytetrafluoroethylene, polyethylene, and molybdenum disulfide.

[0021] As an optional implementation, the first material layer comprises, by mass fraction, 30-60% polyimide, 10-40% polytetrafluoroethylene, and 5-15% molybdenum disulfide; and / or

[0022] The second material layer comprises, by mass fraction, 10-40% polyimide, 30-60% polytetrafluoroethylene, and 5-15% molybdenum disulfide.

[0023] Secondly, embodiments of this application provide a method for preparing a sliding bearing with a polymer coating, the method comprising:

[0024] A sliding metal layer is prepared on the circumferential surface of the shaft base, and then the surface of the sliding metal layer is modified to make the surface of the sliding metal layer into a modified curved surface to adapt to the deformation under load.

[0025] A polymer material layer is prepared on the surface of the sliding metal layer. The polymer material layer includes a first material layer and a second material layer. Along the extension direction of the shaft matrix, the first material layer is attached to the middle of the sliding metal layer, and the second material layer is attached to both ends of the sliding metal layer. The wear resistance of the first material layer is higher than that of the second material layer.

[0026] As an optional implementation, preparing a polymer material layer on the surface of the sliding metal layer includes:

[0027] A polymer material slurry is coated onto the surface of the sliding metal layer and then cured to form a polymer material layer.

[0028] Optionally, the coating method includes one of spraying, scraping, and screen printing;

[0029] Optionally, the curing temperature is 150–350℃, and the curing time is 3–8 hours.

[0030] As an optional implementation, preparing a sliding metal layer on the circumferential surface of the shaft substrate includes: using laser cladding to clad metal powder onto the shaft substrate to form a sliding metal layer.

[0031] As an optional implementation, the metal powder includes copper alloy powder, wherein the median particle size Dv50 of the copper alloy powder is greater than 10 μm, and the mass specific surface area of ​​the copper alloy powder is 100–300 m². 2 / kg.

[0032] In the above implementation process, the specific surface area of ​​the copper alloy powder is controlled to be 100-300 m². 2 / kg, meaning that the copper alloy powder is not a smooth sphere, but has a relatively rough surface, which can reduce the reflectivity of the laser, so that the laser energy can be better absorbed. This allows for a more complete melting effect at a lower laser energy, reducing the possibility of bubble formation. Consequently, the metal powder has a better cladding effect, and the resulting sliding bearing can withstand a larger load, meeting the requirements of wind power.

[0033] As an optional implementation method, the specific surface area of ​​the copper alloy powder is 150–250 m². 2 / kg.

[0034] During the above implementation process, the specific surface area of ​​the copper alloy powder is controlled to be 150–250 m². 2 The / kg ratio ensures both effective melting of the laser cladding process and good cladding performance. It also maintains good powder feeding, reducing blockages and ensuring smooth cladding operation.

[0035] As an optional implementation, the particle size range of the copper alloy powder does not exceed 50 μm.

[0036] In the above implementation process, controlling the particle size distribution of copper alloy powder within a narrow range can make the melting degree of copper alloy powder more uniform, which is beneficial to the cladding effect of laser cladding. This results in the sliding metal layer having better performance, and the sliding bearing containing this sliding metal layer can withstand a larger load, meeting the requirements of wind power.

[0037] As an optional implementation, the median particle size Dv50 of the copper alloy powder is 10–70 μm.

[0038] In the above implementation process, the smaller the particle size of the copper alloy powder, the larger its specific surface area, and the more fully it can be melted at a lower laser cladding energy. On the other hand, the larger the particle size of the copper alloy powder, the better its flowability, and the smoother the cladding process. Therefore, controlling the particle size of the copper alloy powder to 10-70 μm can balance the melting effect and flowability of the copper alloy powder in the laser cladding process.

[0039] As an alternative implementation method, copper alloy powder is prepared by water atomization.

[0040] In the above implementation process, the method of preparing copper alloy powder by water atomization can more easily achieve surface roughening, which helps to simplify the operation process.

[0041] As an optional implementation, the flowability of the copper alloy powder is 15-20 s / 50g.

[0042] As an optional implementation, the copper alloy powder includes ferrous metals; the ferrous metals account for 0.1% to 0.5% of the mass of the copper alloy powder; the ferrous metals include Fe and / or Ni.

[0043] In the above implementation process, since copper is a non-ferrous metal with high reflectivity, its absorption of laser light is not good. By adding ferrous metals, the absorption of laser light by the entire powder is increased, which is conducive to achieving more complete melting of copper alloy powder under the specified laser energy.

[0044] As an optional implementation, the laser beam spot density of laser cladding is 80–120 W / cm². 2 .

[0045] In the above implementation process, the laser beam spot density of the laser cladding is controlled to be 80–120 W / cm². 2 This allows the metal powder to melt more fully, while reducing the possibility of overheating, thereby reducing the loss of alloying elements and improving the performance of the sliding metal layer.

[0046] As an optional implementation, the method further includes: roughening the shaft base to make the surface roughness of the shaft base Ra1.6 to Ra6.3.

[0047] In the above implementation process, by roughening the surface of the shaft base, a larger contact area can be formed between the sliding metal layer and the shaft base, which is beneficial to increasing the bonding force between the sliding metal layer and the shaft base.

[0048] As an optional implementation, the method further includes: heating the sliding metal layer to cause gas to escape from the sliding metal layer, followed by cooling to relieve stress.

[0049] In the above implementation process, by heating and cooling the sliding metal layer, the bubbles and stress are removed, which is beneficial to the performance of the sliding metal layer. Attached Figure Description

[0050] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0051] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0052] Figure 1 This is a schematic diagram of a sliding bearing structure provided in an embodiment of this application;

[0053] Figure 2 A flowchart illustrating the method provided in the embodiments of this application;

[0054] Figure 3 Morphology diagram of copper alloy powder provided in the embodiments of this application;

[0055] Figure 4 Morphology diagram of copper alloy powder provided by existing technology.

[0056] Icons: 1-Axis substrate; 2-Sliding metal layer; 3-Polymer material layer; 31-First material layer; 32-Second material layer. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0058] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0059] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0060] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, terms such as "comprising" and "including" mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0061] Rolling bearings are commonly used between planetary gears and planetary shafts in wind turbines. However, because the blades of wind turbines are subjected to winds of varying magnitudes and directions, the sliding bearings are subjected to loads of varying magnitudes and directions. To ensure the long-term and reliable operation of wind turbines, these rolling bearings are typically expensive to manufacture, and subsequent maintenance and replacement costs are also high.

[0062] Some have proposed using sliding bearings to replace the rolling bearings in current wind turbine gearboxes to improve the above problems. However, sliding bearings are more prone to temperature rise failure. Current sliding bearings generally consist of a shaft base 1 and a sliding metal layer 2. Under load, the pin of this sliding bearing will deform. To accommodate this deformation, the copper alloy surface of the sliding bearing can be modified to withstand a larger maximum operating load. However, even after very high-precision modification, sliding bearings still cannot adapt to the huge loads caused by the frequent start-stop of wind power generation, and the problem of being prone to temperature rise failure still exists.

[0063] The inventor intends to invent a sliding bearing that achieves better adaptive shaping by setting a polymer material layer 3 on the surface of the sliding metal layer 2, thereby compensating for the problem of insufficient shaping accuracy of the surface of the sliding metal layer 2, reducing the shaping difficulty of the sliding bearing, increasing the maximum operating load that the sliding bearing can withstand, and further reducing the possibility of temperature rise failure.

[0064] like Figure 1 As shown, this application provides a sliding bearing with a polymer coating. The sliding bearing includes a shaft base 1, a sliding metal layer 2, and a polymer material layer 3.

[0065] Regarding the shaft base 1, the shaft base 1 is made of steel material, and optionally, it can be made of 45# steel, 20CrMnMo, 20CrMnTi, 40Cr, 42CrMoA, 18CrNiMo7-6 or 34CrNiMo6.

[0066] Regarding the sliding metal layer 2, the sliding metal layer 2 is an alloy layer made of a material different from steel. The alloy layer is a copper-based alloy, an aluminum-based alloy, or a tin-based alloy. More specifically, it is a copper-tin alloy, a copper-aluminum alloy, an aluminum-tin alloy, an aluminum-silicon alloy, or an aluminum-zinc alloy. Furthermore, one or more of the following are added to the metal layer: tin, lead, bismuth, aluminum, graphite, molybdenum disulfide, tungsten disulfide, zinc sulfide, calcium fluoride, and boron nitride. The sliding metal layer 2 is attached to the circumferential surface of the shaft base 1. The surface of the sliding metal layer 2 is a modified curved surface to accommodate deformation under operating loads.

[0067] It should be noted that, in order to form the sliding metal layer 2 on the shaft base 1, the material for forming the sliding metal layer 2 can be applied by welding, sintering, casting, rolling, laser cladding, or other suitable methods. The thickness of the sliding metal layer 2 is 0.4–1.5 mm. The thickness of the sliding metal layer 2 ensures its performance in terms of fatigue strength, friction properties, embeddability, and load-bearing capacity, while also being cost-effective.

[0068] The surface of the sliding metal layer 2 is a modified curved surface, which refers to the curved surface generated by modifying the sliding metal layer 2 to adapt to the deformation after load. This modification is generally to cut the two ends and the middle of the sliding metal layer 2. The degree of cutting is not large, generally a few micrometers. The degree and shape of cutting are obtained by simulation calculation based on the application scenario of the bearing.

[0069] Regarding the polymer material layer 3, the polymer material layer 3 is attached to the surface of the sliding metal layer 2. The polymer material layer 3 includes a first material layer 31 and a second material layer 32. Along the extension direction of the shaft matrix 1, the first material layer 31 is attached to the middle of the sliding metal layer 2, and the second material layer 32 is attached to the two ends of the sliding metal layer 2. The wear resistance of the first material layer 31 is higher than that of the second material layer 32.

[0070] The first material layer 31 is attached to the middle of the sliding metal layer 2, meaning that along the extension direction of the axial substrate 1, the axis of symmetry of the first material layer 31 coincides with the axis of symmetry of the sliding metal layer 2. The second material layer 32 is attached to both ends of the sliding metal layer 2, meaning that the second material layer 32 is attached to areas other than the area where the first material layer 31 is attached.

[0071] Wear resistance, also known as abrasion resistance, refers to the wear resistance of a material, expressed as wear loss or wear index. This wear resistance is obtained through a load rotation test. The test conditions for the load rotation test include: oil lubrication with a viscosity of 320 Pa·s, a unit load of 14 MPa, and a rotational linear speed of 1.2 m / s.

[0072] To apply the polymer layer 3, the raw materials for forming the polymer layer 3 can be prepared into a slurry and coated onto the sliding metal layer 2. If necessary, the raw materials can be cured to form the polymer layer 3. Specifically, the preparation of the first material layer 31 and the second material layer 32 involves preparing the raw materials for the first material layer 31 and the second material layer 32 into slurries, respectively, and coating them onto their corresponding areas, followed by curing. Those skilled in the art should understand that the curing of the first material layer 31 and the second material layer 32 does not need to be completed in one step; they can be completed separately. For example, the slurry of the first material layer 31 can be coated onto the corresponding area first, cured once, and then the slurry of the second material layer 32 can be coated and cured again. Conversely, the slurry of the second material layer 32 can be coated onto the corresponding area first, cured once, and then the slurry of the first material layer 31 can be coated and cured again.

[0073] In some embodiments, the wear resistance of the first material layer 31 is 3 to 6 times that of the second material layer 32. By controlling the ratio of the wear resistance of the first material layer 31 to the wear resistance of the second material layer 32, the entire polymer material layer 3 can adapt to shaping better and faster, so as to withstand greater operating loads when used as a wind turbine gearbox.

[0074] In some embodiments, along the extension direction of the shaft substrate 1, the length of the first material layer 31 is 20% to 40% of the length of the second material layer 32. By controlling the length ratio of the first material layer 31 and the second material layer 32, the coating positions of the first material layer 31 and the second material layer 32 are controlled, which can better match the shaping surface of the sliding metal layer 2. The second material layer 32, which has lower wear resistance, is filled in the shaping recessed area to achieve faster and better adaptive shaping.

[0075] In some embodiments, the thickness of the polymer material layer 3 is 10–30 μm. By controlling the thickness of the polymer material layer 3 to 10–30 μm, the thickness wear requirements for self-healing can be met, while also taking into account the curing effect of the polymer material layer 3, so that the performance of the polymer material layer 3 can be repeatedly utilized.

[0076] In some embodiments, the polymer material layer 3 comprises a resin; in some specific applications, the polymer material layer 3 may also include additives. The resin may be selected from at least one of polyimide polymers, polyamide-imide polymers, polyimide, polysuccinimide, polybismaleimide, polybenzimidazole, polyoxadiazole-benzimidazole, polyimide sulfone, polyurethane, polyester, polyphenylene sulfide, fluoropolymers, polyetheretherketone, alkyd resins, polyacrylates, epoxy resins, phenolic resins, and silicone resins. The additives include at least one of graphite, carbon nanotubes, polytetrafluoroethylene, polyethylene, and molybdenum disulfide.

[0077] For example, the first material layer 31 comprises, by mass fraction, 30-60% polyimide, 10-40% polytetrafluoroethylene, and 5-15% molybdenum disulfide; the second material layer 32 comprises, by mass fraction, 10-40% polyimide, 30-60% polytetrafluoroethylene, and 5-15% molybdenum disulfide. The above is merely an example illustrating the implementation of this solution and is not intended to limit the invention. In other embodiments, those skilled in the art can adjust the composition and ratio of the first and second polymer layers according to actual conditions to satisfy the ratio of wear resistance between the first and second polymer layers.

[0078] like Figure 2 As shown in the embodiment of this application, a method for preparing a sliding bearing with a polymer coating is provided, the method comprising:

[0079] S1. A sliding metal layer 2 is prepared on the circumferential surface of the shaft base 1, and then the surface of the sliding metal layer 2 is modified so that the surface of the sliding metal layer 2 is a parabola to adapt to the deformation under load.

[0080] The aforementioned sliding metal layer 2 can be prepared by welding, sintering, casting, rolling, laser cladding, or other suitable methods. The following example illustrates laser cladding: The shaft substrate 1 is placed horizontally and rotated around its central axis. Then, metal powder and a laser beam are simultaneously sprayed onto the shaft substrate 1. The metal powder and laser beam intersect before reaching the surface of the shaft substrate 1, forming a cladding layer at the circumferential position where the sliding metal layer 2 needs to be attached. During the cladding process, the shaft substrate 1 continuously moves along its axial direction to form a cladding layer at the axial position where the sliding metal layer 2 needs to be attached. The cladding layer is the uncured sliding metal layer 2.

[0081] To increase the bonding force between the sliding metal layer 2 and the shaft substrate 1, in some embodiments, the method further includes roughening the shaft substrate 1 to achieve a surface roughness of Ra1.6 to Ra6.3. Roughening the surface of the shaft substrate 1 allows for a larger contact area between the sliding metal layer 2 and the shaft substrate 1, which is beneficial for increasing the bonding force between them. The inventors believe that a roughness of Ra0.8 to Ra6.3 is suitable. Within this range, the reflectivity and adhesion of the shaft substrate 1 surface can be increased to a certain extent without causing severe surface unevenness, which could lead to uneven cladding. Furthermore, it can reduce the diffusion of elements from the shaft substrate 1 into the sliding metal layer 2, thus reducing the degradation of the sliding metal layer 2's performance. Further, after the roughening treatment, a cleaning process is usually performed to remove impurities such as rust, oil, scale, and iron filings from the surface of the shaft substrate 1 during cladding, improving the reliability and effectiveness of the cladding process.

[0082] In some embodiments, the metal powder includes copper alloy powder, wherein the median particle size Dv50 of the copper alloy powder is greater than 10 μm, and the mass specific surface area of ​​the copper alloy powder is 100–300 m². 2 / kg. The copper alloy powder can be specifically selected from CuNiSn alloy powder, with the mass specific surface area of ​​the copper alloy powder controlled to be 100–300 m². 2 / kg, meaning the copper alloy powder is not a smooth sphere (morphology as follows) Figure 3 As shown), compared to the copper alloy powder used in existing technologies (morphology as shown), Figure 4As shown in the figure, its surface is relatively rough, which can reduce the reflectivity of the laser, so that the laser energy can be better absorbed. It can achieve a more complete melting effect at a lower laser energy, reduce the possibility of generating bubbles, and thus make the metal powder cladding effect better. The resulting sliding bearing can withstand a large load and meet the requirements of wind power.

[0083] In some embodiments, the specific surface area of ​​the copper alloy powder is 150–250 m². 2 / kg. The specific surface area of ​​the copper alloy powder should be controlled to be 150–250 m² / kg. 2 The / kg ratio ensures both effective melting of the laser cladding process and good cladding performance. It also maintains good powder feeding, reducing blockages and ensuring smooth cladding operation.

[0084] In some embodiments, the particle size range of the copper alloy powder does not exceed 50 μm. Controlling the particle size distribution of the copper alloy powder within a narrow range allows for a more uniform melting degree, which is beneficial to the cladding effect of laser cladding. This results in the sliding metal layer 2 having better performance, and the sliding bearing containing this sliding metal layer 2 can withstand a larger load, meeting the requirements of wind power.

[0085] Smaller copper alloy powder particle size results in a larger specific surface area, enabling more thorough melting at lower laser cladding energies. Conversely, larger particle size promotes better flowability and facilitates smooth cladding. In some embodiments, the median particle size Dv50 of the copper alloy powder is 10–70 μm. Copper alloy powder within this particle size range balances melting efficiency and flowability during laser cladding. The inventors believe that a flowability of 15–20 s / 50g is suitable.

[0086] In some embodiments, copper alloy powder is prepared by water atomization. The specific heat capacity of water is 4.2 kJ / (kg×℃), and the specific heat capacity of air is 1.003 kJ / (kg×℃). Therefore, the cooling rate of water atomization is 4 times that of air atomization. Because of the fast cooling rate, the copper alloy powder does not have time to spheroidize. Therefore, the method of preparing copper alloy powder by water atomization can more easily achieve surface roughening, which helps to simplify the operation process.

[0087] Because copper is a non-ferrous metal with high reflectivity, its absorption of laser light is poor. In some embodiments, the copper alloy powder includes ferrous metals; the ferrous metals account for 0.1% to 0.5% of the mass of the copper alloy powder; the ferrous metals include Fe and / or Ni. By adding ferrous metals, the absorption of laser light by the entire powder is increased, which is beneficial for achieving more complete melting of the copper alloy powder under the specified laser energy.

[0088] In some embodiments, the laser beam spot density of laser cladding is 80–120 W / cm². 2 By controlling the laser beam spot density of laser cladding to 80–120 W / cm² 2 This allows the metal powder to melt more fully, while reducing the possibility of overheating, thereby reducing the loss of alloying elements and improving the performance of the sliding metal layer 2.

[0089] To further improve the performance of the sliding metal layer 2, in some embodiments, the method further includes heating the sliding metal layer 2 to cause the gas in the sliding metal layer 2 to escape, followed by cooling to eliminate stress. By heating and cooling the sliding metal layer 2, the removal of bubbles and the elimination of stress are achieved, which is beneficial to the performance of the sliding metal layer 2.

[0090] S2. A polymer material layer 3 is prepared on the surface of the sliding metal layer 2. The polymer material layer 3 includes a first material layer 31 and a second material layer 32. Along the extension direction of the axial matrix 1, the first material layer 31 is attached to the middle part of the sliding metal layer 2, and the second material layer 32 is attached to the two ends of the sliding metal layer 2. The wear resistance of the first material layer 31 is higher than that of the second material layer 32.

[0091] In some embodiments, preparing a polymer material layer 3 on the surface of the sliding metal layer 2 includes: coating a polymer material slurry onto the surface of the sliding metal layer 2 and then curing it to form a polymer material layer 3; wherein the coating method includes one of spraying, scraping and screen printing, the curing temperature is 150 to 350°C, and the curing time is 3 to 8 hours.

[0092] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0093] Examples 1-11 and Comparative Examples 1-3

[0094] A method for preparing a sliding bearing with a polymer coating, the method comprising:

[0095] The shaft base is horizontally mounted on the machine tool, with the laser cladding nozzle perpendicular to the upper surface of the shaft base and 10mm away from the shaft surface. The motor is started to rotate the shaft base, simultaneously delivering copper alloy powder, laser, and protective argon gas into the laser cladding nozzle. The laser power is 3000W. The copper alloy powder melts into a liquid state under laser heating and is sprayed onto the surface of the base shaft. At the same time, the inert gas protection prevents the alloy from being oxidized. The laser cladding nozzle moves horizontally (i.e., in the axial direction of the base shaft) under the drive of the motor until the entire surface of the shaft base to be clad is completely covered.

[0096] The main parameter controls for each embodiment and comparative example are shown in the table below:

[0097]

[0098] The performance of the sliding bearings provided in Examples 1 to 11 and Comparative Examples 1 to 3 was tested, and the results are shown in the table below:

[0099] Porosity Location of stomata Maximum pore diameter Shear bonding force Example 1 0.80％ mating surface 100μm 220MPa Example 2 0.50％ The entire cross section 70μm 240MPa Example 3 1.00％ mating surface 100μm 200MPa Example 4 1.20％ mating surface 120μm 200MPa Example 5 0.20％ The entire cross section 20μm 280MPa Example 6 1.00％ The entire cross section 100μm 220MPa Example 7 0.50％ The entire cross section 70μm 230MPa Example 8 0.80％ mating surface 100μm 220MPa Example 9 1.00％ mating surface 110μm 210MPa Example 10 0.70％ mating surface 100μm 230MPa Example 11 0.50％ The entire cross section 70μm 240MPa Comparative Example 1 1.30％ mating surface 130μm 190MPa Comparative Example 2 0.80％ mating surface 100μm 200MPa Comparative Example 3 1.20％ mating surface 120μm 200MPa

[0100] As can be seen from the table above, the sliding metal layer prepared by the method provided in the embodiments of this application has a small porosity (below 1.2%) and a small pore diameter (below 120 μm), and thus has a large shear bonding force (above 200 MPa).

[0101] Comparison of data from Examples 1, 4, and 5 and Comparative Examples 1 and 2 shows that as the specific surface area of ​​the copper alloy powder gradually increases, the shear bonding force exhibits a trend of first increasing and then decreasing. This indicates that the specific surface area of ​​the copper alloy powder should be controlled between 100 and 300 m². 2 / kg is a good range; furthermore, the specific surface area should be controlled between 175 and 250 m². 2 / kg is a better range, especially for a specific surface area of ​​250m². 2 At approximately 0.2% / kg, the porosity of the entire sliding metal layer is controlled at 0.2%, the maximum pore diameter is controlled at 20 μm, and the pores are not concentrated on the bonding surface, but are distributed relatively evenly throughout the sliding metal layer, further improving the performance of the sliding metal layer.

[0102] By comparing the data from Examples 1, 6 to 8 and Comparative Example 3, it can be seen that as the specific surface area of ​​the copper alloy powder gradually increases, the shear bonding force shows a trend of first increasing and then decreasing. It can be seen that the median particle size Dv50 of the copper alloy powder is controlled in the range of 10 to 70 μm. In particular, when the median particle size Dv50 is about 60 μm, the porosity of the entire sliding metal layer is controlled at 0.5%, the maximum pore diameter is controlled at 70 μm, and the pores are not concentrated on the bonding surface, but are distributed relatively evenly in the entire sliding metal layer, which further improves the performance of the sliding metal layer.

[0103] A comparison of the data from Examples 1 and 9 to 11 shows that as the particle size variation of the copper alloy powder gradually decreases, the performance of the entire sliding metal layer becomes better and better.

[0104] Examples 12-27 and Comparative Examples 4-6

[0105] A polymer material layer was prepared on the sliding metal layer of the sliding bearing provided in Example 1. The main parameters of each example and comparative example are controlled as shown in the table below:

[0106]

[0107] The sliding bearings provided in Examples 12-27 and Comparative Examples 4-6 were tested to determine their maximum operating load capacity. The test procedure was as follows: under lubricated conditions, a gradual loading test was conducted at a rotational speed of 0.5 m / s until the temperature exceeded the limit temperature of 85°C, at which point the maximum operating load capacity was obtained. The lubricating oil used was VG320. The load was increased by 10% at a time, and each load test lasted for 8 hours. If the temperature exceeded the limit temperature of 85°C after 8 hours, further loading was performed. The results are shown in the table below:

[0108] Maximum operating load (MPa) Example 12 28 Example 13 27 Example 14 27 Example 15 26 Example 16 29 Example 17 28 Example 18 26 Example 19 25 Example 20 28 Example 21 28 Example 22 26 Example 23 26 Example 24 28 Example 25 28 Example 26 26 Comparative Example 4 16.2 Comparative Example 5 19.18 Comparative Example 6 17.8

[0109] As shown in the table above, the sliding bearings prepared using the method provided in the embodiments of this application can withstand large operating loads, at least 25 MPa. A comparison of Examples 15-18 and Example 12 shows that as the wear resistance ratio of the first and second material layers increases, the maximum operating load that can be withstood first increases and then decreases. Therefore, controlling the wear resistance ratio of the first and second material layers between 3 and 6 is a preferred range. A comparison of Examples 19-22 and Example 12 shows that as the ratio of the length of the first material layer to the length of the second material layer increases, the maximum operating load that can be withstood first increases and then decreases. Therefore, controlling the ratio of the length of the first material layer to the length of the second material layer between 20% and 40% is a preferred range. A comparison of Examples 23-26 and Example 12 shows that as the thickness of the polymer material layer increases, the maximum operating load that can be withstood first increases and then decreases. Therefore, controlling the thickness of the polymer material layer between 15 and 25 μm is a preferred range.

[0110] The above description is merely a specific embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A sliding bearing with a polymer coating, characterized in that, The sliding bearing includes: Shaft base; A sliding metal layer is attached to the circumferential surface of the shaft base, and the surface of the sliding metal layer is a modified curved surface to adapt to deformation under service load. A polymer material layer is attached to the surface of the sliding metal layer. The polymer material layer includes a first material layer and a second material layer, extending along the axial direction of the shaft matrix. The first material layer is attached to the middle part of the sliding metal layer, and the second material layer is attached to other areas of the sliding metal layer outside the area where the first material layer is attached. The wear resistance of the first material layer is higher than that of the second material layer.

2. The sliding bearing with a polymer coating according to claim 1, characterized in that, The relationship between the first material layer and the second material layer satisfies at least one of the following: A) The wear resistance of the first material layer is 3 to 6 times that of the second material layer; wherein the wear resistance is determined by a load rotation test, and the test conditions for the load rotation test include: oil lubrication with a viscosity of 320 Pa·s, a unit load of 14 MPa, and a rotational linear speed of 1.2 m / s; B) Along the axial direction of the shaft base, the length of the first material layer is 20% to 40% of the length of the second material layer.

3. The sliding bearing with a polymer coating according to claim 1, characterized in that, The polymer material layer satisfies at least one of the following: C) The thickness of the polymer material layer is 10~30μm; D) The polymer material layer comprises at least one of the following: polyimide polymer, polyamide-imide polymer, polyimide, polysuccinimide, polybismaleimide, polybenzimidazole, polyoxadiazole-benzimidazole, polyimide sulfone, polyurethane, polyester, polyphenylene sulfide, fluoropolymer, polyetheretherketone, alkyd resin, polyacrylate, epoxy resin, phenolic resin, and silicone resin; E) The composition of the polymer material layer also includes at least one of graphite, carbon nanotubes, polytetrafluoroethylene, polyethylene and molybdenum disulfide.

4. The sliding bearing with a polymer coating according to claim 3, characterized in that, The first material layer comprises, by mass fraction, 30%-60% polyimide, 10%-40% polytetrafluoroethylene, and 5%-15% molybdenum disulfide; and / or The second material layer comprises, by mass fraction, 10%-40% polyimide, 30%-60% polytetrafluoroethylene and 5%-15% molybdenum disulfide.

5. A method for preparing a sliding bearing with a polymer coating, characterized in that, The method includes: A sliding metal layer is prepared on the circumferential surface of the shaft base, and then the surface of the sliding metal layer is modified so that the surface of the sliding metal layer is a modified curved surface to adapt to the deformation under the load of the service state. A polymer material layer is prepared on the surface of the sliding metal layer. The polymer material layer includes a first material layer and a second material layer, extending along the axial direction of the shaft matrix. The first material layer is attached to the middle part of the sliding metal layer, and the second material layer is attached to other areas of the sliding metal layer outside the area where the first material layer is attached. The wear resistance of the first material layer is higher than that of the second material layer.

6. The method for preparing a sliding bearing with a polymer coating according to claim 5, characterized in that, The preparation of the polymer material layer on the surface of the sliding metal layer includes: A polymer slurry is coated onto the surface of the sliding metal layer and then cured to form a polymer layer; and / or The coating method includes one of spraying, scraping, and screen printing; and / or The curing temperature is 150~350℃, and the curing time is 3~8h.

7. The method for preparing a sliding bearing with a polymer coating according to claim 5, characterized in that, The preparation of the sliding metal layer on the circumferential surface of the shaft substrate includes: using laser cladding to clad metal powder onto the shaft substrate to form the sliding metal layer.

8. The method for preparing a sliding bearing with a polymer coating according to claim 7, characterized in that, The metal powder includes copper alloy powder, and the copper alloy powder satisfies at least one of the following: F) The median particle size Dv50 of the copper alloy powder is greater than 10 μm; G) The specific surface area of ​​the copper alloy powder is 100 m². 2 / kg ~300m 2 / kg; H) The particle size range of the copper alloy powder shall not exceed 50 μm; I) The median particle size Dv50 of the copper alloy powder is 10μm ~ 70μm; J) The copper alloy powder is prepared by water atomization; K) The fluidity of the copper alloy powder is 15 s / 50g ~ 20 s / 50g; L) The copper alloy powder includes ferrous metals; the ferrous metals account for 0.1% to 0.5% of the mass of the copper alloy powder; the ferrous metals include Fe and / or Ni.

9. The method for preparing a sliding bearing with a polymer coating according to claim 7, characterized in that, The laser beam spot density of the laser cladding is 80 W / cm²~120 W / cm².

10. The method for preparing a sliding bearing with a polymer coating according to claim 7, characterized in that, The method further includes at least one of the following: M) The shaft base is roughened to make the surface roughness of the shaft base Ra0.6~Ra6.3; N) The sliding metal layer is heated to allow the gas in the sliding metal layer to escape, and then cooled to relieve stress.

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