Self-lubricating retainer with functional structure and preparation method thereof and bearing

Abstract

The application provides a self-lubricating retainer with a functional structure, a preparation method of the self-lubricating retainer and a bearing. The self-lubricating retainer comprises, in sequence from outside to inside along a radial direction, an outer functional zone, a copper ring and an inner functional zone. Raw materials of the outer functional zone and the inner functional zone comprise polytetrafluoroethylene and copper powder. On any radial section of the retainer, the outer functional zone and the inner functional zone satisfy any one of the following two conditions: (1) the outer functional zone and the inner functional zone each only comprise one layer, and the components of the raw materials of the outer functional zone and the inner functional zone are the same; (2) the outer functional zone and the inner functional zone each comprise n layers of functional layers combined in the radial direction, n is greater than or equal to 2, the components of the raw materials of the outer functional zone and the inner functional zone are symmetrically distributed with the copper ring as a central layer, and the content of the copper powder gradually decreases from the central layer to the surface, and the content of the polytetrafluoroethylene gradually increases from the central layer to the surface. The retainer prepared by the application has high strength, good heat conduction performance and good wear resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of bearing manufacturing, in particular to a self-lubricating retainer with functional structure and a preparation method thereof and a bearing. BACKGROUND

[0002] Solid lubricated bearings are mainly applied in the field of space mechanism with low speed or intermittent operation due to their self-lubrication, long service life, no pollution and radiation resistance. At present, the retainer with polytetrafluoroethylene as base material is mainly used in the field of aerospace solid lubricated bearings. Through the operation of the bearing, the retainer material with lubricating properties is transferred to the steel ball and raceway to form a solid lubricating film, so as to realize the friction reduction property and ensure the service life of the bearing.

[0003] With the development of space technology, higher requirements are put forward for the high-speed performance of solid lubricated bearings. With the increase of bearing speed, the impact and collision of steel ball on the retainer will be increased due to high-speed effect. When the stress on the retainer exceeds the yield strength of polytetrafluoroethylene base material, the retainer will be broken. Some bearings are provided with two metal reinforcing rings at both ends of the retainer, and the retainer and the reinforcing ring are riveted together through rivets to improve the overall strength of the retainer. However, the riveting process is complex, the requirement for labor is high, and the qualified rate of finished products is low. In addition, the thermal conductivity of non-metallic retainer is poor. For high-speed bearings without cooling system, the increase of heat generation will cause the temperature rise of the bearing, which will seriously affect the operation performance and reliability of the bearing. At the same time, the high-speed effect will aggravate the friction and wear of the retainer pocket, which is easy to cause the accumulation of abrasive dust, resulting in bearing jamming and sticking phenomenon, and even cause the main shaft to stop or even cause accidents.

[0004] Therefore, it is necessary to design a new self-lubricating retainer and a preparation method thereof, which can improve the thermal conductivity and wear resistance of the retainer while improving the strength of the retainer. SUMMARY

[0005] In order to solve the problems in the prior art, the present application provides a self-lubricating retainer with functional structure and a preparation method thereof and a bearing. The retainer prepared by the method of the present application not only has high strength, but also has good thermal conductivity and wear resistance.

[0006] In order to achieve the above purpose, the specific scheme adopted by the present application is as follows:

[0007] On the one hand, the present application discloses a self-lubricating retainer with functional structure, which comprises an outer functional zone, a copper ring and an inner functional zone in sequence along the radial direction from the outer surface to the inner surface of the retainer. The raw material of the outer functional zone and the inner functional zone comprises polytetrafluoroethylene and copper powder. In any radial section of the retainer, the outer functional zone and the inner functional zone satisfy any one of the following two conditions:

[0008] (1), the outer functional area and the inner functional area only contain one layer, and the components of the raw materials of the outer functional area and the inner functional area are the same;

[0009] (2), the outer functional area and the inner functional area contain n layers of functional layers combined in the radial direction, n≥2, the components of the raw materials of the outer functional area and the inner functional area are symmetrically distributed with the copper ring as the center layer, and the content of copper powder gradually decreases from the center layer to the surface, while the content of polytetrafluoroethylene gradually increases from the center layer to the surface.

[0010] Further, the raw materials of the outer functional area and the inner functional area include polytetrafluoroethylene 50-80%, copper powder 10-50%, and polyimide fiber 0-10% by weight percentage, and the length of the polyimide fiber is 0.1-3mm.

[0011] On the other hand, the application discloses a preparation method of a self-lubricating retainer with a functional structure, mainly including the following steps:

[0012] Step S1, processing copper ring

[0013] The copper ring is processed by using copper bar, and a plurality of pre-catch holes are processed equidistantly on the side wall of the copper ring;

[0014] Step S2, preparing mixed material

[0015] Take polytetrafluoroethylene 50-80%, copper powder 10-50%, and polyimide fiber 0-10% by weight percentage, respectively, and place the polytetrafluoroethylene in a low-temperature environment below 5℃ for 12h, then put it into a high-speed mixer together with other raw materials, control the water cooling flow rate of the high-speed mixer so that the temperature in the high-speed mixer is below 10℃, mix uniformly to obtain the mixed material;

[0016] If the outer functional layer and the inner functional area only contain one layer, only one kind of mixed material can be prepared; if the outer functional area and the inner functional area contain n layers of functional layers combined in the radial direction, n kinds of mixed materials are prepared;

[0017] Step S3, preparing finished product retainer

[0018] Put the copper ring in the barrel-shaped mold, make sure the copper ring is in the middle of the mold cavity, and fill the mixed material prepared in step S2 into the mold cavity; Put the mold into the spark plasma sintering furnace, keep the pressure at 3-10 MPa for 3-5 min at a temperature of 30 DEG C, then quickly heat to 250-280 DEG C at a heating rate of 60-150 DEG C / min, the sintering pressure is 15-50 MPa, the holding time is 2-7 min, then heat down to 330-360 DEG C at the same heating rate, the sintering pressure is 3-10 MPa, the holding time is 3-8 min, finally water cooling to below 100 DEG C in 3-5 min, and the green body is prepared; Anneal the green body at 150-200 DEG C for 2-4 h, then scan the green body using industrial CT to determine the position of the copper ring and the pre-boss hole, use a high-speed precision lathe to process the green body to the target size and process the boss hole, and obtain the processed body;

[0019] If the outer functional layer and the inner functional area each contain only one layer, the preparation is completed, and the finished product retainer is obtained; if the outer functional area and the inner functional area each contain n layers of functional layers combined in the radial direction, the processed body obtained in the previous step is placed back into the mold, different mixed materials are filled into the mold, and step S3 is repeated n-1 times, and the finished product retainer is obtained.

[0020] Further, in step S1, the height of the copper ring = the height of the finished product retainer - (1-3) mm, the diameter of the pre-boss hole = the diameter of the boss hole of the finished product retainer + (1-2) mm, and the wall thickness of the copper ring = the wall thickness of the finished product retainer / (1.5-2); the middle diameter of the copper ring is related to the bearing guide mode, wherein when the bearing guide mode is outer guide, the middle diameter of the copper ring = the middle diameter of the finished product retainer + (0.5-1.0) mm; when the bearing guide mode is inner guide, the middle diameter of the copper ring = the middle diameter of the finished product retainer - (0.5-1.0) mm.

[0021] Further, in step S3, if the outer functional area and the inner functional area each contain n layers of functional layers combined in the radial direction, when the Mth layer is processed, 1

[0022] Further, in step S3, the mold is prepared from carbon microsphere-based fine particle isostatic pressing graphite, the graphite has a bending strength of 70-100 MPa, a thermal conductivity of 70-100 W / m·K, and a density of 1.75-1.90 g / cm 3 .

[0023] Further, the height of the mold = 3 x the height of the copper ring, the inner diameter of the mold = the outer diameter of the copper ring + (5-8) mm, and the outer diameter of the mold = (1.5-2) x the inner diameter of the mold.

[0024] Further, the roughness of the inner and outer surfaces of the copper ring is not less than 45 μm.

[0025] In still another aspect, the application discloses a bearing comprising a cage, which is the self-lubricating cage with the functional structure.

[0026] Advantages:

[0027] (1) The self-lubricating cage designed in the application can realize the compatibility of multiple parameters such as strength, heat conduction, wear resistance and lubrication, the copper ring is used as the support layer of the cage, the strength of the cage is effectively enhanced, the heat conduction performance of the cage is improved, and the risk of fracture, heating and poor wear resistance of the cage under high speed is reduced.

[0028] (2) The application adopts discharge plasma sintering, compared with traditional polytetrafluoroethylene cold pressing and sintering, the sintering time is effectively shortened from 4-6 hours to within 20 minutes, the problems such as deformation of the copper ring at high temperature caused by the traditional sintering process are avoided, and the internal stress is further released by combining annealing treatment, so that the machining precision of the finished cage is ensured.

[0029] (3) The application effectively solves the problem of poor adhesion between polytetrafluoroethylene and metal materials by designing a formula and controlling a processing technology, and avoids the separation of layers during the processing process. In addition, the application realizes the functionalization of the pocket structure by prefabricating the pocket, and controls the stress points of the steel ball and the pocket at the copper ring, so that the problem of poor wear resistance of the cage during high-speed operation is solved.

[0030] (4) The application uses carbon microsphere-based fine particle isostatic pressing graphite as a graphite mold, the graphite mold has high mechanical strength and good heat conductivity, the material of the large-size cage produced by sintering is uniform, the core is not opaque, and the service life is long.

[0031] (5) The application uses high-strength and high-modulus polyimide short fiber modified polytetrafluoroethylene, which effectively improves the wear resistance of polytetrafluoroethylene, and unlike common glass fibers, polyimide has certain self-lubricating properties, so that under high-speed operation of the bearing, the abrasive dust can also act as a lubricant, and the abrasion of the raceway will not occur. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 CT detection diagram of the blank in Example 1. DETAILED DESCRIPTION

[0033] The technical solutions of the present application will be clearly and completely described below in combination with specific embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the protection scope of the present application.

[0034] The present application provides a self-lubricating retainer and a preparation method thereof and a bearing, which improves the strength while effectively improving the thermal conductivity and wear resistance of the material.

[0035] The self-lubricating retainer in the present application comprises, in sequence along the radial direction from the outer surface to the inner surface, an outer functional zone, a copper ring and an inner functional zone, and the raw materials of the outer functional zone and the inner functional zone comprise polytetrafluoroethylene and copper powder; on any radial section of the retainer, the outer functional zone and the inner functional zone satisfy any one of the following two conditions:

[0036] (1) the outer functional zone and the inner functional zone each comprise only one layer, and the components of the raw materials of the outer functional zone and the inner functional zone are the same;

[0037] (2) the outer functional zone and the inner functional zone each comprise n layers of functional layers combined in the radial direction, n≥2, the components of the raw materials of the outer functional zone and the inner functional zone are symmetrically distributed with the copper ring as the central layer, and the content of the copper powder gradually decreases from the central layer to the surface, while the content of the polytetrafluoroethylene gradually increases from the central layer to the surface.

[0038] Among them, the raw materials of the outer functional zone and the inner functional zone comprise, in percentage by weight, polytetrafluoroethylene 50-80%, copper powder 10-50%, and polyimide fiber 0-10%, and the length of the polyimide fiber is 0.1-3 mm.

[0039] The preparation method thereof will be described in detail below. The preparation method of the self-lubricating retainer mainly comprises the following steps:

[0040] Step S1, processing a copper ring

[0041] The copper ring is processed by using a copper bar, and a plurality of pre-catch holes are processed equidistantly on the side wall of the copper ring; wherein the height of the copper ring = the height of the finished retainer - (1-3) mm, the diameter of the pre-catch hole = the diameter of the catch hole of the finished retainer + (1-2) mm, and the wall thickness of the copper ring = the wall thickness of the finished retainer / (1.5-2); the middle diameter of the copper ring is related to the guiding mode of the bearing, wherein when the guiding mode of the bearing is external guiding, the middle diameter of the copper ring = the middle diameter of the finished retainer + (0.5-1.0) mm; when the guiding mode of the bearing is internal guiding, the middle diameter of the copper ring = the middle diameter of the finished retainer - (0.5-1.0) mm;

[0042] Step S2, preparing a mixture

[0043] Take polytetrafluoroethylene 50~80%, copper powder 10~50%, polyimide fiber 0~10% by weight percentage, respectively, put polytetrafluoroethylene in low temperature environment below 5℃ for 12h, then put it into the high speed mixer with other raw materials, control the water cooling flow rate of high speed mixer to make the temperature in high speed mixer below 10℃, mix evenly to get the mixture;

[0044] If the outer functional layer and the inner functional area each contain only one layer, only one kind of mixture can be prepared; if the outer functional area and the inner functional area each contain n layers of functional layers combined in the radial direction, n kinds of mixtures are prepared;

[0045] Step S3, preparing the finished product holder

[0046] Prepare the mold, which is made of carbon microsphere-based fine particle isostatic pressed graphite, the graphite has a bending strength of 70~100MPa, a thermal conductivity of 70~100W / m·K, and a density of 1.75~1.90g / cm 3 ; Place the copper ring in the barrel-shaped mold, ensuring that the copper ring is in the middle of the mold cavity, and fill the mixture prepared in step S2 into the mold cavity; Place the mold in a spark plasma sintering furnace, and press at a temperature of 30℃ under a pressure of 3~10MPa for 3~5min, then rapidly heat to 250~280℃ at a heating rate of 60~150℃ / min, the sintering pressure is 15~50MPa, the holding time is 2~7min, then heat down at the same heating rate to 330~360℃, the sintering pressure is 3~10MPa, the holding time is 3~8min, finally water cooling to below 100℃ in 3~5min to obtain the blank; Anneal the blank at 150~200℃ for 2~4h, then scan the blank using industrial CT to determine the position of the copper ring and the pre-pockets, use a high-speed precision lathe to machine the blank to the target size and process the pockets to obtain the machined body;

[0047] If the outer functional layer and the inner functional area each contain only one layer, the preparation is completed to obtain the finished product holder; if the outer functional area and the inner functional area each contain n layers of functional layers combined in the radial direction, the machined body obtained in the previous step is placed back into the mold, different mixtures are filled into the mold, and step S3 is repeated n-1 times to obtain the finished product holder.

[0048] Wherein, the mold height = 3 x copper ring height, the mold inner diameter = copper ring outer diameter + (5~8) mm, the mold outer diameter = (1.5~2) x mold inner diameter.

[0049] In step S3, if the outer functional zone and the inner functional zone both comprise n layers of functional layers combined in the radial direction, when the Mth layer is processed, 1 < M ≤ n, the diameter of the hole = the diameter of the pre-hole - ((1-2) / n)*M, so that the area around the hole also has n circles of functional layers in the axial direction, and the nth circle is closest to the center of the hole, and the first circle is farthest from the center of the hole.

[0050] Embodiment 1

[0051] The inner diameter of the retainer is set to d = 29.0 mm, the outer diameter is set to D = 35.0 mm, the height is set to H = 11.0 mm, and the hole diameter Db is set to = 7.5 mm. Under the above parameter settings, the five-step process of the present application is described as follows:

[0052] S1, processing of the copper ring

[0053] The copper bar is roughly processed into a copper ring, the height of the copper ring = the height of the finished retainer - 1 = 10.0 mm, the pre-hole is processed at equal intervals, the pre-hole diameter = the finished retainer hole diameter + 1 = 8.5 mm, the copper ring wall thickness = the finished retainer wall thickness / 1.5 = ((35.0-29.0) / 2) / 1.5 = 2 mm, the copper ring outer diameter = 33.5 mm, and a large cutting edge tool is used during processing to make the surface of the copper ring rougher, thereby improving the bonding force between different materials and avoiding delamination;

[0054] S2, preparation of the mixture

[0055] Polytetrafluoroethylene 50% and copper powder 50% are taken by weight percentage, respectively. The polytetrafluoroethylene is placed in a low-temperature environment below 5℃ for 12 hours in advance, and then is placed together in a high-speed mixer for stirring. The water cooling flow rate of the high-speed mixer is controlled so that the temperature in the high-speed mixer is below 10℃. The mixture is prepared by mixing;

[0056] S3, mold composition

[0057] The mold is prepared from carbon microsphere-based fine particle isostatic pressing graphite. The graphite has a bending strength of 70 MPa, a thermal conductivity of 100 W / m·K, and a density of 1.75 g / cm 3 . The mold height = 3 × the copper ring height = 30.0 mm, the mold inner diameter = the copper ring outer diameter + 5 = 38.5 mm, and the mold outer diameter = 2 × the mold inner diameter = 77.0 mm.

[0058] S4, discharge plasma sintering forming

[0059] After the copper ring is placed in the middle of the mold, it is ensured that the copper ring is in the middle of the mold cavity, the mixed material prepared in step S2 is filled into the mold cavity, so that the mixed material is filled on both sides of the copper ring and in the pre-hole; then, under the condition of 30 DEG C and 3 MPa, pressure is kept for 4 min, the temperature is rapidly increased to 280 DEG C at a rate of 150 DEG C / min, the sintering pressure is 15 MPa, the holding time is 2 min, the temperature is increased to 350 DEG C at the same rate, the sintering pressure is 3 MPa, the holding time is 3 min, then water cooling is performed to reduce the temperature below 100 DEG C in 3 min, so that the blank is obtained;

[0060] S5, precision machining of the retainer

[0061] The blank is annealed at 150 DEG C for 3 h, then the copper ring position and size, especially the pre-hole position, are determined by scanning the blank using an industrial CT, as shown in the figure, wherein the white part is the copper ring and the gray part is the mixed material, and the blank is machined (including size machining and hole machining) using a high-speed precision lathe, in the process, the machining speed is controlled to ensure the machining precision and further avoid defects such as delamination and edge curling, so that the final product is obtained. Figure 1

[0062] Example 2

[0063] The inner diameter of the retainer is set to d = 68.5 mm, the outer diameter is set to D = 78.5 mm, the height is set to H = 17.0 mm, and the hole diameter Db is set to = 11.5 mm, under the setting of the above parameters, the step process of the present application is described as follows:

[0064] S1, machining of the copper ring

[0065] The copper bar is roughly machined into a copper ring, the copper ring height = the height of the finished retainer - 3 = 14.0 mm, the pre-hole diameter = the diameter of the finished retainer hole + 1 = 12.5 mm, the copper ring wall thickness = the wall thickness of the finished retainer / 2 = ((78.5-68.5) / 2) / 2 = 2.5 mm, the copper ring outer diameter = 74.0 mm, and a large cutting edge tool is used to make the surface of the copper ring rougher to improve the bonding force between different materials and avoid delamination.

[0066] S2, preparation of the mixed material

[0067] ​The polytetrafluoroethylene is 60% and the copper powder is 40% by weight percentage, the polytetrafluoroethylene is placed in a low-temperature environment below 5℃ for 12 hours in advance, and then is placed in a high-speed mixer together for stirring, the water cooling flow rate of the high-speed mixer is controlled so that the temperature in the high-speed mixer is below 10℃, and a first mixed material is prepared by mixing; the polytetrafluoroethylene is 80%, the copper powder is 10%, and the polyimide fiber is 10% by weight percentage, the polytetrafluoroethylene is placed in a low-temperature environment below 5℃ for 12 hours in advance, and then is placed in a high-speed mixer together for stirring, the water cooling flow rate of the high-speed mixer is controlled so that the temperature in the high-speed mixer is below 10℃, and a second mixed material is prepared by mixing; the length of the polyimide short fiber is 0.1mm;

[0068] S3, mold structure

[0069] The mold is made of carbon microsphere-based fine particle isostatic pressing graphite, the bending strength of the graphite is 80MPa, the thermal conductivity is 80W / m·K, and the density is 1.85g / cm 3 ; the mold height = 3 x the copper ring height = 42.0mm, the mold inner diameter = the copper ring outer diameter + 8 = 82.0mm, and the mold outer diameter = 1.5 x the mold inner diameter = 123.0mm;

[0070] S4, primary discharge plasma sintering forming

[0071] After the copper ring is placed in the middle of the mold, it is ensured that the copper ring is in the middle of the mold cavity, the first mixed material prepared in step S2 is filled into the mold cavity, and the two sides of the copper ring and the pre-holes are filled with the first mixed material; then under the condition of 30℃ and 10MPa, pressure is maintained for 5min, the temperature is rapidly increased to 260℃ at a rate of 110℃ / min, the pressure is 38MPa, the temperature is maintained for 6min, the temperature is increased at the same rate to 360℃, the pressure is 10MPa, the temperature is maintained for 5min, and then water cooling is performed to reduce the temperature below 100℃ in 4min, to obtain a first blank;

[0072] S5, precision machining of the first blank

[0073] The blank is annealed at 180℃ for 4h, then the first blank is scanned by industrial CT to determine the position and size of the copper ring, especially the position of the pre-hole, and then the first blank is machined (including size machining and hole machining) by using a high-speed precision lathe, to obtain a first machined body, the outer diameter of the first machined body is 76.0mm, the inner diameter is 67.0mm, the height is 16.0mm, and the hole diameter is 12mm;

[0074] S6, secondary discharge plasma sintering forming

[0075] Put the first processing body in the mold, ensure that the first processing body is in the middle of the mold cavity, fill the second mixture prepared in step S2 into the mold cavity, so that the first processing body is filled with the second mixture on both sides and in the pocket; then under the condition of 30℃ and 10MPa, keep pressure for 5min, rapidly heat to 260℃ at 110℃ / min, the pressure is 38MPa, keep temperature for 6min, heat to 360℃ at the same heating rate, the pressure is 10MPa, keep temperature for 5min, then water cooling to below 100℃ in 4min, to obtain the second blank;

[0076] S7, precisely processing the second blank

[0077] Anneal the second blank at 180℃ for 4h, then use industrial CT to scan the second blank to determine the position and size of the copper ring, especially the position of the pre-pocket, then use a high-speed precision lathe to process the second blank (including size processing and pocket processing), control the processing speed in the process to ensure the processing precision and further avoid defects such as delamination and edge curling, to obtain the final product.

[0078] Example 3

[0079] Set the inner diameter of the retainer as d=45.0mm, the outer diameter as D=51.5mm, the height as H=15.0mm, and the pocket diameter Db as =10.0mm, under the setting of the above parameters, the five-step process of the application is described as follows:

[0080] S1, processing of the copper ring

[0081] Coarsely process the copper bar into a copper ring, the copper ring height = the product retainer height - 2 = 13.0mm, the pre-pocket diameter = the product retainer pocket diameter + 2 = 12.0mm, the copper ring wall thickness = the product retainer wall thickness / 1.8 = (51.5-45.0) / 2 / 1.8 = 1.8mm, the copper ring outer diameter = 49.5mm, use a large cutting edge tool when processing to make the surface of the copper ring rougher, to improve the bonding force between different materials and avoid delamination;

[0082] S2, preparation of the mixture

[0083] Take polytetrafluoroethylene 60%, copper powder 35% and polyimide short fibers 5% by weight percentage respectively, place the polytetrafluoroethylene in a low-temperature environment below 5℃ for 12h in advance, then put them together into a high-speed mixer and stir, control the water cooling flow rate of the high-speed mixer so that the temperature in the high-speed mixer is below 10℃, mix and prepare the mixture, and the length of the polyimide short fibers is 3mm;

[0084] S3, mold composition

[0085] The mold is made of carbon microsphere-based fine particle isostatic pressing graphite, the bending strength of the graphite is 100 MPa, the thermal conductivity is 70 W / m·K, and the density is 1.75 g / cm 3 The mold height = 3 x the copper ring height = 39.0 mm, the mold inner diameter = the copper ring outer diameter + 6 = 55.5 mm, and the mold outer diameter = 1.6 x the mold inner diameter = 88.8 mm;

[0086] S4, discharging plasma sintering forming

[0087] After the copper ring is placed in the middle of the mold, it is ensured that the copper ring is in the middle of the mold cavity, and the mixture prepared in step S2 is filled into the mold cavity; then, under the condition of 30 DEG C and 4 MPa, pressure is maintained for 3 min, the temperature is rapidly increased to 250 DEG C at a speed of 60 DEG C / min, the pressure is 50 MPa, and the temperature is maintained for 7 min, the temperature is increased to 330 DEG C at the same speed, the pressure is 4 MPa, and the temperature is maintained for 10 min, and then the temperature is reduced to below 100 DEG C in 5 min by water cooling, to obtain a blank;

[0088] S5, precision machining of the retainer

[0089] After the blank is annealed at 200 DEG C for 3 h, the copper ring position and size are determined by scanning the blank using an industrial CT, especially the position of the pre-hole, and then the blank is machined (including size machining and hole machining) using a high-speed precision lathe, and the machining speed is controlled to ensure the machining accuracy and further avoid defects such as delamination and edge curling, to obtain the final product.

[0090] Comparative Example 1

[0091] Comparative Example 1 is a traditional polytetrafluoroethylene composite retainer, ZYS-PTFE02, i.e., a glass fiber modified polytetrafluoroethylene composite retainer.

[0092] The tensile strength and wear performance of the retainers prepared in Examples 1-3 and Comparative Example are tested, and the results are shown in Table 1.

[0093] Table 1 Performance of the retainers prepared in Examples 1-3 and Comparative Example

[0094]

[0095] From the above table, it can be analyzed that the mechanical properties of the self-lubricating retainer prepared by the present application are significantly improved, and there is no delamination at the fracture of the tensile sample, and the interfacial bonding force is good. The self-lubricating retainer prepared by the present application has excellent friction and wear performance.

[0096] The bearing using the self-lubricating retainer has excellent running-in performance under the condition of 6000 rpm high speed, and does not have abnormal performance such as noise screaming, and after disassembling the bearing, the transferred film state of the raceway is good.

[0097] The self-lubricating retainer can be widely applied in space solid lubrication bearings with higher rotating speed and longer service life, meet the future development needs of space solid lubrication bearings in the field of aviation and aerospace of China, and has remarkable economic and social benefits.

[0098] The above merely describes preferred embodiments of the present application, but does not limit the present application in any form. Any equivalent changes or modifications made according to the spirit of the present application should be covered within the protection scope of the present application.

Claims

1. A self-lubricating cage having a functional structure, characterized by, The self-lubricating retainer comprises, in sequence from the outer surface to the inner surface, an outer functional zone, a copper ring, and an inner functional zone; the raw materials of the outer functional zone and the inner functional zone comprise, by weight percentage, 50-80% polytetrafluoroethylene, 10-50% copper powder, and 0-10% polyimide fiber, the length of the polyimide fiber being 0.1-3 mm; in any radial section of the retainer, the outer functional zone and the inner functional zone satisfy any one of the following two conditions: (1) the outer functional zone and the inner functional zone each comprise only one layer, and the compositions of the raw materials of the outer functional zone and the inner functional zone are the same; (2) the outer functional zone and the inner functional zone each comprise n layers of functional layers combined in the radial direction, n≥2, the compositions of the raw materials of the outer functional zone and the inner functional zone are symmetrically distributed with the copper ring as the central layer, and the content of the copper powder gradually decreases from the central layer to the surface, while the content of the polytetrafluoroethylene gradually increases from the central layer to the surface.

2. A method of manufacturing a self-lubricating cage having a functional structure according to claim 1, characterized by, The method mainly comprises the following steps: Step S1, processing the copper ring The copper ring is processed using a copper bar, and a plurality of pre-pockets are processed equidistantly on the side wall of the copper ring; Step S2, preparing the mixed material 50-80% polytetrafluoroethylene, 10-50% copper powder, and 0-10% polyimide fiber are taken by weight percentage, the polytetrafluoroethylene is placed in a low-temperature environment below 5℃ for 12 h, and then the polytetrafluoroethylene is put into a high-speed mixer together with other raw materials for stirring, the water cooling flow rate of the high-speed mixer is controlled to make the temperature in the high-speed mixer below 10℃, and the mixed material is obtained after uniform mixing; If the outer functional layer and the inner functional zone each comprise only one layer, only one kind of mixed material is prepared; if the outer functional zone and the inner functional zone each comprise n layers of functional layers combined in the radial direction, n kinds of mixed materials are prepared; Step S3, preparing the finished retainer The copper ring is placed in a barrel-shaped mold, ensuring that the copper ring is in the middle of the mold cavity, the mixed material prepared in step S2 is filled into the mold cavity, so that the copper ring is filled with the mixed material on both sides and in the pre-pockets; the mold is placed in a spark plasma sintering furnace, pressure is maintained at 3-10 MPa for 3-5 min at a temperature of 30℃, then the temperature is rapidly raised to 250-280℃ at a heating rate of 60-150℃ / min, the sintering pressure is 15-50 MPa, the holding time is 2-7 min, then the temperature is lowered at the same heating rate to 330-360℃, the sintering pressure is 3-10 MPa, the holding time is 3-8 min, and finally the temperature is lowered to below 100℃ in 3-5 min by water cooling, to obtain a blank; the blank is annealed at 150-200℃ for 2-4 h, then the blank is scanned using an industrial CT to determine the positions of the copper ring and the pre-pockets, the blank is processed to the target size using a high-speed precision lathe, and the pockets are processed, to obtain a processed body; If the outer functional layer and the inner functional zone each comprise only one layer, the preparation is completed, and the finished retainer is obtained; if the outer functional zone and the inner functional zone each comprise n layers of functional layers combined in the radial direction, the processed body obtained in the previous step is placed back into the mold, different mixed materials are filled into the mold, and step S3 is repeated n-1 times, to obtain the finished retainer.

3. A method of manufacturing a self-lubricating cage having a functional structure according to claim 2, characterized in that, In step S1, the height of the copper ring = the height of the finished holder - (1-3) mm, the diameter of the pre-hole = the diameter of the finished holder hole + (1-2) mm, the wall thickness of the copper ring = the wall thickness of the finished holder / (1.5-2); the middle diameter of the copper ring is related to the guiding mode of the bearing, wherein when the guiding mode of the bearing is external guiding, the middle diameter of the copper ring = the middle diameter of the finished holder + (0.5-1.0) mm; when the guiding mode of the bearing is internal guiding, the middle diameter of the copper ring = the middle diameter of the finished holder - (0.5-1.0) mm.

4. The method of claim 3, wherein the self-lubricating cage having a functional structure is prepared by the steps of: In step S3, if the outer functional area and the inner functional area both contain n layers of functional layers combined in the radial direction, when the Mth layer is machined, 1 5. The method for preparing a self-lubricating cage with a functional structure according to claim 2, characterized in that, In step S3, the mold is made of carbon microsphere-based fine particle isostatic pressing graphite, the bending strength of the graphite is 70-100 MPa, the thermal conductivity is 70-100 W / m·K, and the density is 1.75-1.90 g / cm 3 .

6. The method of claim 2, wherein the self-lubricating cage having a functional structure is prepared by the steps of: The height of the mold = 3 x the height of the copper ring, the inner diameter of the mold = the outer diameter of the copper ring + (5-8) mm, and the outer diameter of the mold = (1.5-2) x the inner diameter of the mold.

7. The method of claim 2, wherein the self-lubricating cage having a functional structure is prepared by the steps of: The roughness of the inner and outer surfaces of the copper ring is not less than 45 μm. ​ 8. Bearing comprising a cage, characterized in that, The holder is the self-lubricating holder with a functional structure according to claim 1.

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