Bearing surface hardening method and bearing

Abstract

The invention discloses a bearing surface hardening method and a bearing. The method comprises the following steps: quenching and tempering a steel base body, and processing a plurality of tooth distribution grooves in the quenched and tempered steel base body; welding and fixing the polycrystalline diamond compact coated with the nickel-based brazing filler metal in the tooth distribution groove; filling powder with the thickness not exceeding the specified thickness is subjected to hot spray welding on the surface of the steel base body fixed with the polycrystalline diamond compact; grinding the steel substrate subjected to hot spray welding and powder filling to a design size; welding air holes are filled with the filling powder in a laser cladding mode for hole sealing treatment; and grinding the steel substrate subjected to hole sealing treatment to a designed size. The damage of high-temperature sintering to a steel matrix structure and the wear-resistant alloy blocks can be avoided and reduced, the high strength of a matrix material can be kept, and the wear resistance, impact resistance and erosion resistance of the bearing are greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploration and development, and particularly relates to a bearing surface hardening and a bearing. Background Art

[0002] Conventional radial bearings of positive displacement motors usually adopt traditional TC bearings. The manufacturing process of traditional TC bearings mainly includes the following steps: 1) bonding carbide blocks on the surface of a steel matrix with an adhesive; 2) sleeving another steel sleeve on the surface of the carbide blocks to form a container space on the tube wall; 3) filling the container space formed between the carbide blocks and the steel sleeve with cast tungsten carbide powder by vibration, and adding infiltrating alloys such as copper and tin on it; 4) putting it into a heating furnace and heating to about 1100°C for metallurgical melting and welding; 5) after cooling, machining the steel sleeve and the carbide blocks (including turning the steel sleeve and grinding the carbide) to obtain the finished TC bearing.

[0003] Problems existing in the manufacturing process of traditional TC bearings: 1) The efficiency of bonding carbide blocks is low, and the decomposition of the adhesive during the melting and welding process will also affect the bonding between the carbide and the steel matrix; 2) The heating process is overall heating, with a long heating time, and it is difficult to guarantee the hardness and strength of the steel matrix. During use, the carbide chips are likely to fall off and the matrix is likely to break; 3) The steel sleeve needs to be welded on the steel matrix and then removed after sintering, which is laborious and material-consuming; 4) After the steel sleeve is welded on, there is no way to observe the filling situation of the cast tungsten carbide powder, and only after sintering and removal can defects be found, and it is difficult to repair.

[0004] Due to the above defects of traditional TC bearings, there are problems such as poor wear resistance, easy fracture of the steel matrix, easy fragmentation of the carbide blocks, and falling off of the filler slag and blocks during use. It is easy to cause seizure of the mating surfaces of the inner and outer TC bearings, with a relatively short overall service life and unstable quality.

[0005] At present, Technical Solution 1 for the radial bearing technology of positive displacement motors is to perform quenching and tempering heat treatment after sintering of TC bearings to adjust the matrix structure, reduce the coarsening of the matrix structure grains, and thus avoid the problem of reducing the matrix strength. Solution 2 is a hardening surface preparation method that uses surface welding to disperse carbide chips and plasma surfacing to fill tungsten carbide particles. Summary of the Invention

[0006] The disadvantages of the above Solution 1 are that the cemented carbide blocks are prone to cracking, chipping and overall dimensional changes during the heat treatment process, making subsequent finish machining difficult and resulting in poor reliability and short lifespan of the TC bearings. The disadvantages of the above Solution 2 are that surfacing requires continuous operation and is not conducive to heat dissipation, and the temperature of plasma surfacing is too high with the heat being too concentrated, easily causing too large a temperature difference between the surface and the core of the cemented carbide blocks, leading to cracking of the cemented carbide. It is difficult to control the temperature rise of the surfacing layer. A molten pool needs to be formed on the surface of the steel matrix for surfacing, which easily causes the steel matrix to overheat and reduces the matrix strength. It is difficult to control the interlayer heat preservation during surfacing and cracking is likely to occur. Repeated high-temperature thermal cycling of the surfacing layer easily causes coarsening and non-uniformity of the bonding phase structure of the surfacing layer, affecting the wear resistance and corrosion resistance of the overall hardened surface. Moreover, the operation is relatively complicated and not suitable for small parts and small plane operations with dense arrangement of cemented carbide blocks. With the reduction of cemented carbide blocks, the wear resistance of the overall hardened surface will inevitably decrease, and the reliability and service life cannot be guaranteed either.

[0007] In summary, for the TC bearings prepared by the current TC bearing solutions, there are still problems such as poor reliability and short service life. This further affects the service life and reliability of the drive shaft assembly, resulting in a low overall service life of the downhole motor power system, affecting the drilling efficiency, and also increasing the accident rate of the downhole motor.

[0008] In view of the above problems, the present invention is proposed to provide a bearing surface hardening method and a bearing that overcome or at least partially solve the above problems.

[0009] In a first aspect, an embodiment of the present invention provides a bearing surface hardening method, including:

[0010] Performing quenching and tempering treatment on a steel matrix, and machining a number of tooth-arranging grooves on the steel matrix after the quenching and tempering treatment;

[0011] Welding and fixing a polycrystalline diamond composite sheet wrapped with a nickel-based filler metal in the tooth-arranging grooves;

[0012] Thermal spraying and welding a filling powder with a thickness not exceeding a specified thickness on the surface of the steel matrix fixed with the polycrystalline diamond composite sheet; the filling powder includes Ni60 alloy powder and nickel-coated polycrystalline diamond composite alloy powder;

[0013] Grinding the steel matrix after thermal spraying and welding the filling powder to the designed dimensions;

[0014] Adopting a laser cladding method to fill the filling powder in the welding pores for hole sealing treatment;

[0015] Grinding the steel matrix after the hole sealing treatment to the designed dimensions.

[0016] In some optional embodiments, performing quenching and tempering treatment on the steel matrix includes:

[0017] Heat the steel substrate to a first temperature and hold for a first duration until the internal structure of the steel body transforms into austenite structure;

[0018] After the transformation is completed, transfer the steel substrate to quenching oil for cooling until the austenite structure inside the steel substrate transforms into martensite structure;

[0019] Transfer the steel substrate to a tempering furnace within a preset time, heat it to a second temperature and hold for a second duration, and then transfer the steel substrate to a cooling water tank to cool it to room temperature.

[0020] In some alternative embodiments, machining tooth grooves on the steel substrate includes:

[0021] Machine multiple rows of circumferentially evenly distributed tooth grooves on the steel substrate, and the tooth grooves in adjacent rows are mutually offset and complemented.

[0022] In some alternative embodiments, welding and fixing a polycrystalline diamond composite sheet wrapped with a nickel-based filler metal in the tooth grooves includes:

[0023] Pre-treat the surface of the steel substrate to remove impurities;

[0024] After pre-treatment, preheat the entire steel substrate to a third temperature and hold for a third duration;

[0025] Use a welding method to fix the polycrystalline diamond composite sheet in the tooth grooves on the surface of the steel body. The polycrystalline diamond composite sheet is wrapped with a nickel-based filler metal outside.

[0026] In some alternative embodiments, thermally spray welding a filling powder with a thickness not exceeding a specified thickness on the surface of the steel substrate fixed with a polycrystalline diamond composite sheet includes:

[0027] Heat the steel substrate fixed with a polycrystalline diamond composite sheet to a fourth temperature, and spray a layer of Ni60 self-fluxing alloy powder with a first thickness on the surface of the polycrystalline diamond composite sheet and the gaps between the polycrystalline diamond composite sheets;

[0028] Thermally spray weld 55 - 60wt% Ni60 spray welding powder and 40 - 45wt% nickel-coated polycrystalline diamond composite alloy powder into the gaps between the polycrystalline diamond composite sheets after spraying the Ni60 self-fluxing alloy powder.

[0029] In some alternative embodiments, heat the steel substrate fixed with a polycrystalline diamond composite sheet to a third temperature, and spray a layer of Ni60 self-fluxing alloy powder with a first thickness on the surface of the polycrystalline diamond composite sheet and the gaps between the polycrystalline diamond composite sheets, including:

[0030] Add Ni60 self-fluxing alloy powder to the powder tank of the flame spray gun, adjust the flame type, heat the nickel-based filler metal and preheat the steel substrate to the fourth temperature; the powder tank of the flame spray gun has a device for controlling the powder addition amount;

[0031] Spray and weld Ni60 self - fluxing alloy powder with a first thickness evenly onto the surface of the polycrystalline diamond compact and the gaps between polycrystalline diamond compacts at a preset spray - welding angle, spray - welding distance, and spray - welding moving speed.

[0032] In some alternative embodiments, after spraying Ni60 self - fluxing alloy powder, hot spray - weld 55 - 60 wt% Ni60 spray - welding powder and 40 - 45 wt% nickel - coated polycrystalline diamond composite alloy powder into the gaps between polycrystalline diamond compacts, including:

[0033] Add 55 - 60 wt% Ni60 spray - welding powder and 40 - 45 wt% nickel - coated polycrystalline diamond composite alloy powder into the powder tank of the flame spray gun, adjust the flame type, start from one end of the spray - welding surface, fill the 55 - 60 wt% Ni60 spray - welding powder and 40 - 45 wt% nickel - coated polycrystalline diamond composite alloy powder into the gaps between polycrystalline diamond compacts, and heat the surface of the steel substrate to a fifth temperature with the flame to melt the filled powder into a molten mirror surface;

[0034] Move the flame to the next part and continue the operation of filling the powder and melting it until the end of the spray - welding surface is reached.

[0035] In some alternative embodiments, the above - mentioned method further includes:

[0036] After hot spray - welding is completed and before the grinding operation, put the hot - spray - welded steel substrate into a box - type resistance furnace and slowly cool it to a sixth temperature, then take it out of the resistance furnace for air cooling; the sixth temperature is ≤200°C.

[0037] In some alternative embodiments, adopt laser cladding to fill the filling powder in the welding pores for hole - sealing treatment, including:

[0038] Check the pores on the spray - welded surface of the steel substrate after hot spray - welding and filling the powder;

[0039] Pre - place 55 - 60 wt% Ni60 spray - welding powder and 40 - 45 wt% nickel - coated polycrystalline diamond composite alloy powder at the pore sites;

[0040] Adopt a laser cladding method with a laser power of 1500 - 1800 W and a beam diameter of 2 mm ± 1 mm to melt the filling powder pre - placed at the pore sites for pore plugging and filling.

[0041] In some alternative embodiments, the above - mentioned method further includes:

[0042] Put the hole - sealed steel substrate into a box - type resistance furnace and slowly cool it to room temperature, then take it out of the resistance furnace for air cooling.

[0043] In a second aspect, an embodiment of the present invention provides a polycrystalline diamond radial bearing, comprising: a substrate, a polycrystalline diamond composite sheet, and a filling powder;

[0044] Tooth grooves are provided on the surface of the substrate, and the polycrystalline diamond composite sheets are welded and fixed in the tooth grooves;

[0045] The gaps between the polycrystalline diamond composite sheets are spray-welded and filled with the filling powder; the filling powder includes Ni60 alloy powder and nickel-coated polycrystalline diamond composite alloy powder.

[0046] In some optional embodiments, the filling powder of the above polycrystalline diamond radial bearing includes 55-60 wt% Ni60 spray-welding powder and 40-45 wt% nickel-coated polycrystalline diamond composite alloy powder.

[0047] In some optional embodiments, multiple rows of circumferentially evenly distributed tooth grooves are provided on the steel substrate of the above polycrystalline diamond radial bearing, and the tooth grooves in adjacent rows are mutually offset and compensated.

[0048] In some optional embodiments, the polycrystalline diamond composite sheet of the above polycrystalline diamond radial bearing includes a polycrystalline diamond sheet and a nickel-based filler metal wrapped outside the polycrystalline diamond sheet.

[0049] In some optional embodiments, a polycrystalline diamond radial bearing is manufactured using the above bearing surface hardening method.

[0050] The beneficial effects of the above technical solutions provided by the embodiments of the present invention at least include:

[0051] By performing quenching and tempering treatment on a steel matrix, a number of tooth grooves are machined on the steel matrix after quenching and tempering treatment; a polycrystalline diamond composite sheet wrapped with a nickel-based brazing filler metal is welded and fixed in the tooth grooves; the diamond composite sheet is welded in the tooth grooves by welding, which makes up for the problem of poor bonding between the cemented carbide and the steel matrix caused by the bonding method. A filling powder with a thickness not exceeding a specified thickness is thermally sprayed and welded on the surface of the steel matrix fixed with the polycrystalline diamond composite sheet; the filling powder includes Ni60 alloy powder and nickel-coated polycrystalline diamond composite alloy powder; compared with the traditional method, there is no need to remove the steel sleeve on the steel matrix, saving materials and labor, and because this method does not require a steel sleeve to be put on, the filling situation of the filling powder can be observed on the surface of the steel matrix, defects can be found and repaired in time. The steel matrix after thermal spraying and welding the filling powder is ground to the designed size; the filling powder is filled in the welding pores by laser cladding for hole sealing treatment; the steel matrix after hole sealing treatment is ground to the designed size. This method can weld and fill the polycrystalline diamond composite sheet on the surface of the steel matrix by thermal spraying and welding, making the combination of the steel matrix and the composite sheet more firm. During the thermal spraying and welding process, there is no need to continuously heat the steel matrix, the heat will not be concentrated, it is not easy to damage the hardness of the steel matrix, it has strong wear resistance, improves the service life of the bearing, and at the same time can visually observe the filling effect on the surface of the steel matrix, repair in time, and has high reliability.

[0052] Other features and advantages of the present invention will be described in the following specification, and, in part, will be obvious from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained by the structures specifically pointed out in the written specification, claims, and drawings.

[0053] The technical solutions of the present invention will be further described in detail below through the drawings and embodiments. Description of the Drawings

[0054] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention. In the drawings:

[0055] Figure 1 is a flow chart of the method for hardening the surface of the bearing in the first embodiment of the present invention;

[0056] Figure 2 is a flow chart of the quenching and tempering process of the steel matrix of the radial bearing in the first embodiment of the present invention;

[0057] Figure 3 is for the first embodiment of the present invention Figure 3 is a cross-sectional view of the tooth groove of the radial bearing;

[0058] Figure 4Expansion diagram of tooth grooves arranged on the outer surface of the steel matrix in Embodiment 1 of the present invention;

[0059] Figure 5 Partial schematic diagram of the polycrystalline diamond composite sheet and the tooth grooves arranged in Embodiment 1 of the present invention;

[0060] Figure 6 Cross-sectional view of the bearing after spot welding in Embodiment 1 of the present invention;

[0061] Figure 7 Schematic diagram of flame spray welding in Embodiment 1 of the present invention;

[0062] Figure 8 Circumferential expansion diagram of the filled steel matrix in Embodiment 1 of the present invention;

[0063] Figure 9 Structural diagram of the polycrystalline diamond radial bearing in Embodiment 2 of the present invention. Detailed implementation manners

[0064] Hereinafter, exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art.

[0065] To solve the problems existing in the prior art, an embodiment of the present invention provides a method for hardening the surface of a bearing, which overcomes the problems faced by TC bearings through a polycrystalline diamond bearing surface composite hardening process, and improves the use reliability and service life of downhole tools.

[0066] Embodiment 1

[0067] An embodiment 1 of the present invention provides a method for hardening the surface of a bearing, and its process is as Figure 1 shown, including the following steps:

[0068] Step S101: Perform quenching and tempering treatment on the steel matrix, and process a plurality of tooth grooves on the steel matrix after quenching and tempering treatment;

[0069] Step S102: Weld and fix the polycrystalline diamond composite sheet wrapped with nickel-based brazing filler metal in the tooth grooves;

[0070] Step S103: Thermally spray weld a filling powder with a thickness not exceeding a specified thickness on the surface of the steel matrix fixed with the polycrystalline diamond composite sheet; the filling powder includes Ni60 alloy powder and nickel-coated polycrystalline diamond composite alloy powder;

[0071] Step S104: Grind the steel matrix after thermally spray welding the filling powder to the designed dimensions;

[0072] Step S105: Perform hole sealing treatment by filling the welding pores with the filling powder in a laser cladding manner;

[0073] Step S106: Grind the steel matrix after hole sealing treatment to the designed dimensions.

[0074] Preferably, in the above step S101, the quenching and tempering treatment of the steel matrix includes:

[0075] Heat the steel matrix to the first temperature and keep it warm for the first duration until the internal structure of the steel body is transformed into austenite structure;

[0076] After the transformation is completed, transfer the steel matrix into quenching oil for cooling until the austenite structure inside the steel matrix is transformed into martensite structure;

[0077] Transfer the steel matrix into a tempering furnace and heat it to the second temperature and keep it warm for the second duration within a preset time, and then transfer the steel matrix into a cooling water tank to cool it to room temperature.

[0078] Preferably, the first temperature is 860±10°C, and the first duration is 2 - 2.5 hours; the second temperature is 630±10°C, and the second duration is 2.5 - 3 hours.

[0079] Generally, the quenching heating temperature range of ultra-high strength steel for quenching and tempering is 820 - 900°C. In this embodiment, the selected steel material is 30CrNi2MoV, and the quenching heating and holding temperature range of this steel is 830 - 900°C. Generally, considering the equipment and workpiece shape to avoid cracking and low quenching hardness, 840 - 880°C is selected, and 860°C is an optimized choice according to the equipment situation and production practice. The holding time is a value calculated based on the effective heating size and furnace loading of the workpiece matrix, that is, the larger the workpiece size and the furnace loading, the longer the time. Different effective heating sizes and furnace loadings of the workpiece matrix result in different values. Even for the same size cylinder furnace loading, extending the time by within 30 minutes has limited adverse effects on the quality.

[0080] The steel matrix of the radial bearing produced by the method of the present invention is made of ultra-high strength steel containing chromium, nickel, molybdenum, vanadium and other alloys with excellent tempering resistance. After quenching and tempering treatment, the comprehensive mechanical properties such as strength and toughness of the steel matrix are improved as much as possible. The wall thickness of the steel matrix should be as thick as possible, that is, the outer diameter size and inner diameter size of the matrix should maintain a large size difference, which can avoid the steel matrix from heating up too fast during the spray welding process and also avoid serious deformation of the steel matrix.

[0081] Figure 2It is a flow chart of the quenching and tempering process for the steel matrix of a radial bearing. The ultra-high-strength steel matrix 1-1 containing alloys such as chromium, nickel, molybdenum, and vanadium is heated in a high-temperature heating furnace. During the heating-up process 4-1, it is heated to 860 ± 10 °C. During the heat preservation process 4-2 at 860 ± 10 °C, the heat preservation time is 2 - 2.5 hours to fully complete the austenitization transformation of the internal structure of the steel matrix 1-1. After completing the austenitization transformation of the internal structure of the steel matrix 1-1, the steel matrix is quickly transferred into rapid quenching oil for the rapid cooling process 4-3. The temperature of the steel matrix 1-1 is quickly cooled to room temperature, maximizing the transformation of the internal structure of the steel from austenite structure to martensite structure. Then, within no more than 2 hours, the steel matrix is transferred into a tempering furnace and heated to 630 ± 10 °C, that is, process 4-4. After the process 4-5 of heat preservation at 630 ± 10 °C for 2.5 - 3 hours, the steel matrix is quickly transferred into a cooling water tank and cooled to room temperature in the process 4-6. Rapid cooling with water at room temperature here can better improve the impact toughness of the steel matrix.

[0082] Preferably, in the above step S101, machining tooth grooves on the steel matrix includes:

[0083] Machining multiple rows of circumferentially evenly distributed tooth grooves on the steel matrix, and the tooth grooves in adjacent rows are mutually offset and complementary.

[0084] Figure 3 It is a sectional view of the tooth grooves of a radial bearing. Regular milling machining of tooth grooves 1-2 is carried out on the circumferential surface of the steel matrix 1-1, and the bottom of the tooth grooves 1-2 is machined into an R arc. Figure 4 It is a developed view of the tooth grooves on the outer surface of the steel matrix. There are multiple rows of circumferentially evenly distributed tooth grooves 1-2 on the steel matrix 1-1, and the tooth grooves in adjacent rows are mutually offset and complementary. The tooth grooves 1-2 account for about 45 - 50% of the working surface. It is necessary to ensure both the hardness of the friction surface with high wear resistance and the sufficient strength of the steel matrix 1-1 to meet the overall mechanical properties of the downhole radial bearing without overall fracture.

[0085] Preferably, in the above step S102, welding and fixing the polycrystalline diamond composite sheet wrapped with nickel-based brazing filler metal in the tooth grooves includes:

[0086] Pre-treating the surface of the steel matrix to remove impurities;

[0087] After pre-treatment, preheating the whole steel matrix to a third temperature and keeping it for a third duration;

[0088] Using a welding method to fix the polycrystalline diamond composite sheet in the tooth grooves on the surface of the steel body. The polycrystalline diamond machine composite sheet is wrapped with nickel-based brazing filler metal.

[0089] Preferably, the third temperature is 300 ± 10 °C, and the third duration is 2 - 3 hours; the welding method is spot welding, the spot welding current is 700 - 850 A, and the pretreatment includes degreasing and defatting. The holding duration and the electric welding current vary depending on the size of the workpiece substrate, the calculated value based on the furnace loading, and the size and furnace loading.

[0090] Figure 5 It is a partial schematic diagram of a polycrystalline diamond compact and a tooth - setting groove, including a steel matrix 1 - 1, a tooth - setting groove 1 - 2, a nickel - based filler metal 2 - 1 wrapped around, and a polycrystalline diamond compact 2 - 2. The bottom of the tooth - setting groove is flat. The bottom surface of the nickel - based filler metal 2 - 1 wrapped around is in full contact with the surface of the tooth - setting groove 1 - 2 of the steel matrix 1 - 1. The polycrystalline diamond compact 2 - 2 wrapped with nickel - based filler metal is spot - welded into the tooth - setting groove 1 - 2 by electric welding, so that the polycrystalline diamond compact 2 - 2 wrapped with nickel - based filler metal is fixed in the tooth - setting groove 1 - 2 without displacement. The spot - welding current is evenly distributed, avoiding excessive local current. During the spot - welding process, the bottom part of the nickel - based filler metal 2 - 1 wrapped around the polycrystalline diamond compact melts, which is beneficial to avoiding the temperature of the polycrystalline diamond compact not exceeding 700 °C. The nickel - based filler metal 2 - 1 protects the polycrystalline diamond compact from local abnormal temperature rise during spot - welding and the subsequent spray - welding process. At the same time, the polycrystalline diamond compact is uniformly stressed, firmly welded, and can maintain a good stress state. The cross - sectional view of the bearing after final spot - welding is shown in Figure 6 As shown, it includes a steel matrix 1 - 1, a polycrystalline diamond compact 2 - 2 wrapped with nickel - based filler metal, and a gap 5 - 1 between polycrystalline diamond compacts. After the polycrystalline diamond compact 2 - 2 wrapped with nickel - based filler metal is fixed on the surface of the steel matrix 1 - 1, a gap 5 - 1 between polycrystalline diamond compacts is formed.

[0091] Preferably, in the above step S104, spraying a filling powder with a thickness not exceeding a specified thickness on the surface of the steel matrix fixed with polycrystalline diamond compacts includes:

[0092] Heating the steel matrix fixed with polycrystalline diamond compacts to a fourth temperature, and spraying a layer of Ni60 self - fluxing alloy powder with a first thickness on the surface of the polycrystalline diamond compact and the gap between polycrystalline diamond compacts;

[0093] Thermal spray - welding 55 - 60 wt% Ni60 spray - welding powder and 40 - 45 wt% nickel - coated polycrystalline diamond composite alloy powder into the gap between polycrystalline diamond compacts after spraying the Ni60 self - fluxing alloy powder.

[0094] During the trial production process, it was found that if the Ni60 spray-welding powder exceeded 60% and the content of nickel-coated polycrystalline diamond composite alloy powder exceeded 45%, the spray-welding effect deteriorated, easily causing uneven spray-welded layers and cracking; while the lower the content of Ni60 spray-welding powder and nickel-coated polycrystalline diamond composite alloy powder, the lower the hardness of the spray-welded layer, reducing the wear resistance of the workpiece's spray-welded layer. Therefore, choosing 55 - 60wt% Ni60 spray-welding powder and 40 - 45wt% nickel-coated polycrystalline diamond composite alloy powder is a moderate choice that takes into account both the fusion welding performance and the hardened surface hardness.

[0095] During hot spray-welding, 55 - 60wt% Ni60 spray-welding powder and 40 - 45wt% nickel-coated polycrystalline diamond composite alloy powder 6 - 1 with a total thickness not exceeding 3mm are spray-welded into the peripheral gap around the polycrystalline diamond composite sheet 2 - 2 wrapped by nickel-based filler metal to fill the hardening gap. As the thickness of the spray-welded layer increases, the thickness of the heat-affected zone increases, and the degree of reduction in the matrix strength increases. Therefore, the thickness of the spray-welded layer needs to be selected according to the wear resistance requirements and the requirements for the impact resistance of the matrix in the comprehensive practical use conditions; the proportion of nickel-coated polycrystalline diamond composite alloy powder in the spray-welded composite alloy powder should not exceed 45wt%. Exceeding this proportion will reduce the bonding strength of the spray-welded layer and cause difficulties in subsequent grinding processing. During this process, the overall temperature of the steel matrix 1 - 1 should be controlled not to exceed the upper limit of the tempering temperature during its quenching and tempering treatment, which can ensure that the overall strength of the steel matrix is not reduced, and can not only ensure the overall mechanical properties such as the overall impact resistance of the radial bearing, but also greatly improve the reliability, wear resistance, and corrosion resistance of the radial bearing.

[0096] Preferably, the steel matrix fixed with the polycrystalline diamond composite sheet is heated to a third temperature, and a first thickness of Ni60 self-fluxing alloy powder is sprayed onto the surface of the polycrystalline diamond composite sheet and the gap between the polycrystalline diamond composite sheets, including:

[0097] Add Ni60 self-fluxing alloy powder to the powder tank of the flame spray gun, adjust the flame type, heat the nickel-based filler metal, and preheat the steel matrix to a fourth temperature; the powder tank of the flame spray gun has a device for controlling the powder addition amount;

[0098] Spray-weld a first thickness of Ni60 self-fluxing alloy powder onto the surface of the polycrystalline diamond composite sheet and the gap between the polycrystalline diamond composite sheets evenly at a preset spray-welding angle, spray-welding distance, and spray-welding moving speed.

[0099] Preferably, the fourth temperature is 300 - 320°C, the spray-welding angle is the angle between the spray gun nozzle and the spray-welding surface of 85 - 90°, the spray-welding distance is the straight-line distance between the nozzle and the spray-welding surface of 170 - 180mm, and the spray-welding moving speed is the moving speed of the nozzle of 8 - 10 meters per minute;

[0100] The flame spray gun is an oxygen-acetylene powder flame spray gun. During the spray welding process, the flame type is a neutral flame, the oxygen pressure is 0.55 MPa, and the acetylene pressure is 0.06 MPa. The oxygen-acetylene powder flame spray gun is used because it is the most common and the operators are most familiar with it, which can reduce the adverse effects caused by unfamiliar equipment and auxiliary atmosphere.

[0101] Figure 7 It is a schematic diagram of flame spray welding. The spraying surface consists of a steel matrix 1-1, a toothed groove 1-2, a polycrystalline diamond composite sheet 2-2 wrapped with nickel-based filler metal, and molten Ni60 self-fluxing alloy powder. An oxygen-acetylene powder flame spray gun with a powder tank 7-3 having a device for controlling the powder addition amount is used, and the powder tank is filled with Ni60 self-fluxing alloy powder. Turn on the switch 7-4, adjust the flame core 7-1 to a neutral flame, first heat the nickel-based filler metal 2-1 wrapped around it, and preheat the surrounding steel matrix 1-1 to 300 - 320 °C. Spray a layer of Ni60 self-fluxing alloy powder not exceeding 3 mm on the surface of the polycrystalline diamond composite sheet 2-2 wrapped with nickel-based filler metal and the gap 5-1 between the polycrystalline diamond composite sheets, tightly wrap the polycrystalline diamond composite sheet 2-2 and firmly weld it in the toothed groove on the surface of the steel matrix. During spray welding, the oxygen pressure of the spray gun is 0.55 MPa, the acetylene pressure is 0.06 MPa, the angle between the spray gun nozzle 7-2 and the spray welding surface is 85 - 90°, the linear distance between the nozzle and the spray welding surface is 180 mm, and the moving speed of the nozzle is 8 - 10 m / min.

[0102] During hot spray welding, the following control key points should be noted:

[0103] (1) Strictly ensure that the polycrystalline diamond composite sheet 2-2 wrapped with nickel-based filler metal 2-1 is tightly wrapped and sealed with Ni60 self-fluxing alloy powder to avoid oxidation.

[0104] (2) During the hot spray welding process, continuously move the position of the flame core 7-1 to prevent local overheating of the polycrystalline diamond composite sheet 2-2 and the steel matrix 1-1.

[0105] (3) Continuously move the position of the flame core so that the Ni60 self-fluxing alloy powder spray coating evenly covers and wraps the polycrystalline diamond composite sheet wrapped with nickel-based filler metal.

[0106] (4) Strictly control the overall temperature rise of the steel matrix and the temperature rise of the polycrystalline diamond composite sheet. The temperature of the polycrystalline diamond composite sheet shall not exceed 700 °C, and the overall temperature of the steel matrix shall not exceed 630 °C.

[0107] (5) During the operation process, strictly control the heating and cooling rates of the polycrystalline diamond composite sheet to avoid excessive temperature difference inside and outside the polycrystalline diamond composite, which may cause cracks in the polycrystalline diamond composite sheet (2-2).

[0108] Preferably, 55-60 wt% Ni60 spray-welding powder and 40-45 wt% nickel-coated polycrystalline diamond composite alloy powder are thermally spray-welded into the gaps of polycrystalline diamond compacts after spraying Ni60 self-fluxing alloy powder, including:

[0109] Add 55-60 wt% Ni60 spray-welding powder and 40-45 wt% nickel-coated polycrystalline diamond composite alloy powder into the powder tank of the flame spray gun, adjust the flame type, start from one end of the spray-welding surface, fill the gaps of the polycrystalline diamond machine compacts with 55-60 wt% Ni60 spray-welding powder and 40-45 wt% nickel-coated polycrystalline diamond composite alloy powder, and heat the surface of the steel substrate to the fifth temperature with the flame to melt the filling powder into a molten mirror surface;

[0110] Move the flame to the next part and continue to perform the operation of filling the powder and melting it until the end of the spray-welding surface is reached.

[0111] In some alternative embodiments, the fifth temperature is not higher than 700 °C, the spray-welding angle is the angle between the spray gun nozzle and the spray-welding surface of 85-90°, the spray-welding distance is the linear distance between the nozzle and the spray-welding surface of 20-25 mm, and the spray-welding moving speed is the moving speed of the nozzle of 8-10 m / min;

[0112] The flame spray gun is an oxygen-acetylene powder flame spray gun. During the spray-welding process, the flame type is a neutral flame, the oxygen pressure is 0.50 MPa, and the acetylene pressure is 0.05 MPa.

[0113] After the thermal spray-welding of the polycrystalline diamond compact surface is completed, quickly replace the powder in the powder tank 7-3 of the flame spray gun with 55-60 wt% Ni60 spray-welding powder and 40-45 wt% nickel-coated polycrystalline diamond composite alloy powder 6-1. Start heating from one end of the spraying part and gradually increase the surface temperature of the steel substrate to about 700 °C. When the surface of the steel substrate is heated to the point where the Ni60 self-fluxing alloy composite powder starts to wet, a molten mirror surface appears. Adjust the flame to a softer neutral flame, with an oxygen pressure of 0.50 MPa and an acetylene pressure of 0.05 MPa, and slightly increase the gas flow rate. Spray-weld 55-60 wt% Ni60 spray-welding powder and 40-45 wt% nickel-coated polycrystalline diamond composite alloy powder 6-1: intermittently press the powder feeding switch to spray 55-60 wt% Ni60 spray-welding powder and 40-45 wt% nickel-coated polycrystalline diamond composite alloy powder, and spray-weld the gaps 5-1 of the polycrystalline diamond compacts with 55-60 wt% Ni60 spray-welding powder and 40-45 wt% nickel-coated polycrystalline diamond composite alloy powder starting from one end of the spray-welding surface; at the same time, move the flame to 7 mm of the spray-welding surface and melt it into a molten mirror surface, and then immediately move the flame core 7-1 to the next part to continue the operation of spraying and melting the powder. Repeat this process until the end of the spray-welding surface. Figure 6The gap 5-1 of the polycrystalline diamond compact is spray-welded with 55-60 wt% Ni60 spray-welding powder and 40-45 wt% nickel-coated polycrystalline diamond composite alloy powder 6-1 to fill each part of the gap 5-1 of the polycrystalline diamond compact, forming Figure 8 The circumferential development view of the filled steel matrix shown, including the polycrystalline diamond compact 2-2 and 55-60 wt% Ni60 spray-welding powder and 40-45 wt% nickel-coated polycrystalline diamond composite alloy powder 6-1.

[0114] When spray-welding the gap, the following control points should be noted:

[0115] (1) Strictly ensure that the polycrystalline diamond compact (2-2) is tightly wrapped and sealed to avoid oxidation.

[0116] (2) Spray-weld 55-60 wt% Ni60 spray-welding powder and 40-45 wt% nickel-coated polycrystalline diamond composite alloy powder 6-1: The angle between the spray gun nozzle 7-2 and the spray-welding surface is 85-90°, the flame is adjusted to a softer neutral flame, the oxygen pressure is 0.50 MPa, the acetylene pressure is 0.05 MPa, and the gas flow rate is slightly increased. The linear distance between the nozzle and the spray-welding surface is 20-25 mm, and the moving speed of the nozzle is 8-10 m / min.

[0117] (3) Strictly control the powder feeding amount of the spray gun and strictly control the spray-welding thickness.

[0118] (4) Remelting of the spray coating: The angle between the spray gun nozzle and the spray-welding surface is 90°, the linear distance between the nozzle and the spray-welding surface is 7 mm. After the flame melting mirror reflection appears on the spray-welding surface, immediately move the nozzle, and the remelting time should be shortened as much as possible.

[0119] (5) Minimize the overall temperature rise of the polycrystalline diamond compact (2-2) and the steel matrix (1-1) as much as possible.

[0120] (6) During the process, continuously move the position of the flame core 7-1 to prevent local overheating of the polycrystalline diamond compact 2-2 and the steel matrix 1-1, and timely remove the molten slag and gas through the core purge.

[0121] (7) During the spray-welding process, strictly control the temperature of the polycrystalline diamond compact not to exceed 700 °C, and the overall temperature of the steel matrix not to exceed 630 °C.

[0122] (8) During the operation process, strictly control the heating and cooling rates of the polycrystalline diamond compact to avoid cracks in the diamond composite caused by excessive temperature difference inside and outside the polycrystalline diamond compact.

[0123] (9) Pay attention to wind prevention during the operation process.

[0124] Preferably, the above step S103 further includes:

[0125] After hot spraying and welding are completed and before grinding operation, the steel matrix after hot spraying and welding is placed in a box-type resistance furnace and slowly cooled to the sixth temperature, and then taken out of the resistance furnace for air cooling; the sixth temperature is ≤200°C.

[0126] After hot spraying and welding are completed, the whole welded part is quickly placed in a 300°C box-type resistance furnace for slow cooling, and after slow cooling to below 200°C, it is taken out of the furnace for air cooling.

[0127] Preferably, in the above step S105, the filling powder is filled in the welding pores by laser cladding for hole sealing treatment, including:

[0128] Check the pores on the sprayed surface of the steel matrix after filling with hot spraying and welding powder.

[0129] Pre-place 55-60wt% Ni60 spraying powder and 40-45wt% nickel-coated polycrystalline diamond composite alloy powder at the pore gaps.

[0130] Adopt a laser power of 1500-1800W and a laser cladding method with a beam diameter of 2mm ± 1mm to melt the filling powder pre-placed at the pore gaps for pore plugging and filling.

[0131] After pre-placing 55-60wt% Ni60 spraying powder and 40-45wt% nickel-coated polycrystalline diamond composite alloy powder at the pore gaps near the pores on the sprayed surface, adopt a laser power of 1500-1800W and a laser radiation heating method with a beam diameter of 2mm ± 1mm to melt and seal the pore gaps.

[0132] Preferably, the above method further includes:

[0133] Put the steel matrix after hole sealing into a box-type resistance furnace and slowly cool it to room temperature, and then take it out of the resistance furnace for air cooling.

[0134] In the above steps S104 and S106, grinding is carried out using a grinding tool. For example, in step S104, a ceramic grinding wheel is used to grind the sprayed working surface of the workpiece to the designed size; in step S106, a ceramic grinding wheel is used to finely grind the hole-sealing area and the entire working surface of the workpiece to the designed size. It is difficult to carry out the final grinding process with a diamond grinding wheel, and a customized ceramic grinding wheel needs to be used for grinding. Therefore, the thickness of the polycrystalline diamond composite sheet is preferably selected so that the protruding dimension after spot welding is slightly higher than the surface of the final size. If it is too thick, subsequent grinding will be difficult.

[0135] The following is the specific process of trial production using the method of the present invention:

[0136] Select 30CrNi2MoV steel with strong tempering resistance as the workpiece matrix steel. Material composition: C%: 0.28 - 0.33, Si%: 0.15 - 0.35, Mn%: 0.75 - 1.0, Cr%: 0.75 - 1.0, Ni%: 1.65 - 2.0, Mo%: 0.35 - 0.50, V%: 0.05 - 0.10, P%: ≤0.015, S%: ≤0.015.

[0137] The workpiece adopts a straight cylinder with an outer diameter of 130 mm, an inner diameter of 70 mm, and a length of 290 mm.

[0138] Perform quenching and tempering by quenching heating: Heat the steel matrix to 860 °C and hold for 120 minutes, then quickly transfer it to a quenching oil tank with good stirring ability and cool for 25 minutes. The quenching oil tank can be Houghton K type rapid quenching oil. After spraying the oil, quickly transfer it to a tempering furnace at 630 °C. After the tempering furnace temperature returns to 630 °C again, hold for 150 minutes, and then quickly transfer it to a cooling water tank with a cooling cycle at a water temperature of 30 °C and cool to room temperature. Detect the surface tempering hardness of the workpiece matrix to be 38 - 40 HRC.

[0139] The dimensions of the matrix workpiece before spray welding are: a straight cylinder with an outer diameter of 124 mm, an inner diameter of 74 mm, and a length of 284 mm.

[0140] The work-hardened surface area accounts for about 60% of the overall outer diameter surface area of the workpiece. The toothed area of the polycrystalline diamond composite sheet accounts for about 45 - 50% of the hardened surface area. After spot welding, the polycrystalline diamond composite sheet has no cracking or decarburization, and can be combined with the steel collective, without affecting the firmness.

[0141] Spray weld three different proportions of composite spray welding powders, namely 60wt% Ni60 spray welding powder and 40wt% nickel-coated polycrystalline diamond composite alloy powder, 55wt% Ni60 spray welding powder and 45wt% nickel-coated polycrystalline diamond composite alloy powder, 50wt% Ni60 spray welding powder and 50wt% nickel-coated polycrystalline diamond composite alloy powder, according to the above spray welding process. The thickness of the spray weld fusion layer is 2.5 - 3.0 mm. After grinding with a ceramic grinding wheel, the final thickness of the spray weld layer is 1.5 mm. It is found during the trial production that the hardening process of spraying polycrystalline diamond composite alloy powder into the gaps between polycrystalline diamond composite sheets based on polycrystalline diamond composite sheets finally forms a very wear-resistant hardened surface, ensuring the wear resistance of the hardened surface.

[0142] After machining to the final size, detect the surface hardness of the matrix to be 36 - 38 HRC, the thickness of the heat-affected zone is less than 5 mm, and the thickness of the heat-affected zone is less than 6 - 10 mm of the plasma surfacing process method. It can be judged from the change of the matrix hardness that the matrix strength hardly decreases and does not affect the service life of the steel collective.

[0143] After final inspection, it is found that: the porosity of the spray-welded layer of nickel-coated polycrystalline diamond composite alloy powder with a spray-welded content of ≥ 45 wt% increases significantly, and even local microcracks occur.

[0144] Through production trial, it is found that polycrystalline diamond composite sheets are very difficult to grind. Therefore, the outer diameter dimension of the bearing after spot-welding polycrystalline diamond composite sheets (the maximum dimension to ensure that the bearing can be finally ground round) is slightly larger than the outer diameter dimension of the final bearing product, and the final finished product dimension can be processed. Otherwise, the grinding difficulty and machining time will be increased.

[0145] In the above method of this embodiment, the traditional sintering manufacturing technology of TC bearings is abandoned, and polycrystalline diamond is innovatively applied by spray welding to the surface of a steel matrix subjected to quenching and tempering treatment, which greatly avoids and reduces the damage of high-temperature sintering to the steel matrix structure and wear-resistant alloy blocks, can maintain the high strength of the matrix material, and greatly improves the wear resistance, impact resistance and erosion resistance of the bearing, overcomes the problems of large and easy-to-break grains of the traditional bearing matrix material, easy fragmentation and shedding of alloy blocks, poor wear resistance and erosion resistance, and will greatly improve the service life of the radial bearing of the positive displacement motor.

[0146] Compared with the recently emerging plasma surfacing hardening technology, it overcomes the problems that surfacing requires continuous operation and is not conducive to heat dissipation, the surfacing temperature is too high, the heat is too concentrated, the plasma arc inevitably contacts the cemented carbide block, which is easy to cause too large a temperature difference between the surface and the core of the cemented carbide block, resulting in cracking of the cemented carbide. When the surfacing layer is thick, it is difficult to control the temperature rise of the surfacing layer, which is easy to cause overheating of the steel matrix, and there is the same problem of reducing the matrix strength as the traditional TC bearing sintering manufacturing technology. Poor control of interlayer heat preservation during surfacing is easy to cause cracking, and repeated high-temperature thermal cycles of the surfacing layer are easy to cause coarsening and non-uniformity of the bonding phase structure of the surfacing layer, affecting the wear resistance and corrosion resistance of the overall hardened surface. Moreover, the operation is relatively complicated, not suitable for small parts and small plane operations with complex structures and dense arrangements of cemented carbide blocks, and with the reduction of cemented carbide blocks, the wear resistance of the overall hardened surface will inevitably be reduced.

[0147] Embodiment 2

[0148] Based on the bearing surface hardening method, Embodiment 2 of the present invention provides a polycrystalline diamond radial bearing, the structure of which is shown in Figure 9 as shown, including: a matrix 1-1, polycrystalline diamond composite sheets 2-2 and filling powder 6-1;

[0149] Tooth grooves are provided on the surface of the matrix, and polycrystalline diamond composite sheets are welded and fixed in the tooth grooves;

[0150] The gap between the polycrystalline diamond composite sheets is spray-welded and filled with filling powder; the filling powder includes Ni60 alloy powder and nickel-coated polycrystalline diamond composite alloy powder.

[0151] Preferably, the filling powder of the above polycrystalline diamond radial bearing comprises 55-60wt% Ni60 spray-welding powder and 40-45wt% nickel-coated polycrystalline diamond composite alloy powder.

[0152] Preferably, multiple rows of circumferentially evenly distributed tooth grooves are provided on the steel matrix of the above polycrystalline diamond radial bearing, and the tooth grooves in adjacent rows are mutually offset and complemented.

[0153] Preferably, the polycrystalline diamond composite sheet of the above polycrystalline diamond radial bearing comprises a polycrystalline diamond sheet and a nickel-based filler metal wrapped outside the polycrystalline diamond sheet.

[0154] Preferably, a polycrystalline diamond radial bearing is manufactured by using the above bearing surface hardening method.

[0155] The above polycrystalline diamond radial bearing in the embodiment of the present invention has the capabilities of wear resistance, impact resistance, and erosion resistance, has a longer service life, is high in hardness, is not prone to cracking, and has a higher firmness between the steel matrix of the bearing and the diamond composite sheet.

[0156] Unless specifically stated otherwise, terms such as processing, computing, calculating, determining, displaying, etc. may refer to actions and / or processes of one or more processing or computing systems, or similar devices, which operate on and transform data represented as physical (such as electronic) quantities within the registers or memories of the processing system into other data similarly represented as physical quantities within the memories, registers, or other such information storage, transmission, or display devices of the processing system. Information and signals can be represented using any of a variety of different technologies and methods. For example, the data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0157] It should be understood that the specific order or hierarchy of steps in the disclosed processes is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the scope of the present disclosure. The appended method claims present the elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy.

[0158] In the above detailed description, various features are combined in a single embodiment to simplify the present disclosure. This method of disclosure should not be interpreted as reflecting an intention that the embodiments of the claimed subject matter require more features than those expressly recited in each claim. On the contrary, as reflected in the appended claims, the invention lies in less than all of the features of the single disclosed embodiment. Accordingly, the appended claims are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the invention.

[0159] Those skilled in the art should also understand that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments herein can be implemented as electronic hardware, computer software, or combinations thereof. To clearly illustrate the interchangeability of hardware and software, the above various illustrative components, blocks, modules, circuits, and steps have been generally described in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and the design constraints imposed on the overall system. Skilled artisans may implement the described functionality in a flexible manner for each particular application, but such implementation decisions should not be construed as departing from the scope of the present disclosure.

[0160] The steps of a method or algorithm described in connection with the embodiments herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination thereof. The software modules may be located in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium well known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. Of course, the storage medium may also be integral to the processor. The processor and the storage medium may be located in an ASIC. The ASIC may be located in a user terminal. Of course, the processor and the storage medium may also exist as discrete components in a user terminal.

[0161] For a software implementation, the techniques described in this application can be implemented using modules (e.g., procedures, functions, etc.) that perform the functions described in this application. These software codes can be stored in a memory unit and executed by a processor. The memory unit can be implemented within the processor or outside the processor, and in the latter case, it is coupled to the processor in a communication manner by various means, which are well known in the art.

[0162] The foregoing description includes examples of one or more embodiments. Of course, it is not possible to describe all possible combinations of components or methods for the purpose of describing the above embodiments, but those of ordinary skill in the art should recognize that the various embodiments can be further combined and arranged. Accordingly, the embodiments described herein are intended to embrace all such changes, modifications, and variations that fall within the scope of the appended claims. In addition, with respect to the term "comprising" as used in the specification or claims, that term is inclusive in a manner similar to the term "including," as that term is interpreted when used as a transitional word in a claim. Further, any use of the term "or" in a claim of the specification is to mean "non-exclusive or."

Claims

1. A method for hardening the surface of a bearing, characterized in that, Including: Performing quenching and tempering treatment on a steel substrate, and machining a plurality of tooth grooves on the steel substrate after the quenching and tempering treatment; Welding and fixing a polycrystalline diamond composite sheet wrapped with a nickel-based filler metal in the tooth grooves; Thermal spraying and welding a filling powder with a thickness not exceeding a specified thickness on the surface of the steel substrate fixed with the polycrystalline diamond composite sheet; the filling powder includes Ni60 alloy powder and nickel-coated polycrystalline diamond composite alloy powder; Grinding the steel substrate after thermal spraying and welding the filling powder to a designed size; Adopting a laser cladding method to fill the filling powder in welding pores for hole sealing treatment; Grinding the steel substrate after hole sealing treatment to a designed size.

2. The method according to claim 1, characterized in that, The quenching and tempering treatment of the steel substrate includes: Heating the steel substrate to a first temperature and holding for a first duration until the internal structure of the steel body transforms into austenite structure; After completing the transformation, transferring the steel substrate into quenching oil for cooling until the austenite structure inside the steel substrate transforms into martensite structure; Transferring the steel substrate into a tempering furnace to heat to a second temperature and holding for a second duration within a preset time, and then transferring the steel substrate into a cooling water tank to cool to room temperature.

3. The method according to claim 1, wherein Machining tooth grooves on the steel substrate includes: Machining multiple rows of circumferentially evenly distributed tooth grooves on the steel substrate, and the tooth grooves in adjacent rows are offset and complemented to each other.

4. The method according to claim 1, characterized in that Welding and fixing a polycrystalline diamond composite sheet wrapped with a nickel-based filler metal in the tooth grooves includes: Performing pretreatment on the surface of the steel substrate to remove impurities; After pretreatment, preheating the whole steel substrate to a third temperature and holding for a third duration; Adopting a welding method to fix the polycrystalline diamond composite sheet in the tooth grooves on the surface of the steel body, and the polycrystalline diamond composite sheet is wrapped with a nickel-based filler metal outside.

5. The method according to claim 1, characterized in that, Thermal spraying and welding a filling powder with a thickness not exceeding a specified thickness on the surface of the steel substrate fixed with the polycrystalline diamond composite sheet includes: Heating the steel substrate fixed with the polycrystalline diamond composite sheet to a fourth temperature, and spraying a layer of Ni60 self-fluxing alloy powder with a first thickness on the surface of the polycrystalline diamond composite sheet and the gaps between the polycrystalline diamond composite sheets; Thermal spraying and welding 55-60wt% Ni60 spraying powder and 40-45wt% nickel-coated polycrystalline diamond composite alloy powder into the gaps between the polycrystalline diamond composite sheets after spraying the Ni60 self-fluxing alloy powder.

6. The method according to claim 5, characterized in that, Heating the steel substrate fixed with the polycrystalline diamond composite sheet to a third temperature, and spraying a layer of Ni60 self-fluxing alloy powder with a first thickness on the surface of the polycrystalline diamond composite sheet and the gaps between the polycrystalline diamond composite sheets includes: Adding Ni60 self-fluxing alloy powder into the powder tank of the flame spray gun, adjusting the flame type, heating the nickel-based filler metal and preheating the steel substrate to a fourth temperature; the powder tank of the flame spray gun has a device for controlling the powder addition amount; Spraying and welding a first thickness of Ni60 self-fluxing alloy powder evenly on the surface of the polycrystalline diamond composite sheet and the gaps between the polycrystalline diamond composite sheets at a preset spraying and welding angle, spraying and welding distance and spraying and welding moving speed.

7. The method according to claim 5, characterized in that, Thermal spraying and welding 55-60wt% Ni60 spraying powder and 40-45wt% nickel-coated polycrystalline diamond composite alloy powder into the gaps between the polycrystalline diamond composite sheets after spraying the Ni60 self-fluxing alloy powder includes: Add 55 - 60wt% Ni60 spray welding powder and 40 - 45wt% nickel - coated polycrystalline diamond composite alloy powder into the powder tank of the flame spray gun. Adjust the flame type. Starting from one end of the spray - welding surface, fill the gap of the polycrystalline diamond machine composite sheet with 60wt% Ni60 spray welding powder and 40wt% nickel - coated polycrystalline diamond composite alloy powder, and heat the surface of the steel substrate to the fifth temperature with the flame to melt the filled powder into a molten mirror surface. Move the flame to the next part and continue the operation of filling and melting the powder until the end of the spray - welding surface is reached.

8. The method according to claim 1, wherein It also includes: After the thermal spray - welding is completed and before the grinding operation, put the steel substrate after thermal spray - welding into a box - type resistance furnace and slowly cool it to the sixth temperature, then take it out of the resistance furnace for air cooling; the sixth temperature is ≤200°C.

9. The method according to claim 1, wherein The method of using laser cladding to fill the filling powder in the welding pores for plugging holes includes: Check the pores on the spray - welded surface of the steel substrate after filling with the thermal spray - welding powder. Pre - place 55 - 60wt% Ni60 spray welding powder and 40 - 45wt% nickel - coated polycrystalline diamond composite alloy powder at the pore sites. Adopt a laser cladding method with a laser power of 1500 - 1800W and a beam diameter of 2mm ± 1mm to melt the filling powder pre - placed at the pore sites for pore plugging and filling.

10. The method according to any one of claims 1-9, characterized in that, It also includes: After plugging the holes, put the steel substrate into a box - type resistance furnace and slowly cool it to room temperature, then take it out of the resistance furnace for air cooling.

11. A polycrystalline diamond radial bearing, characterized in that, It includes: Substrate, polycrystalline diamond composite sheet, and filling powder; Tooth - arranging grooves are provided on the surface of the substrate, and the polycrystalline diamond composite sheets are welded and fixed in the tooth - arranging grooves. The gap between the polycrystalline diamond composite sheets is spray - welded and filled with the filling powder; the filling powder includes Ni60 alloy powder and nickel - coated polycrystalline diamond composite alloy powder.

12. The polycrystalline diamond radial bearing according to claim 11, wherein The filling powder includes 55 - 60wt% Ni60 spray welding powder and 40 - 45wt% nickel - coated polycrystalline diamond composite alloy powder.

13. The polycrystalline diamond radial bearing according to claim 11, wherein, Multiple rows of circumferentially evenly - distributed tooth - arranging grooves are provided on the steel substrate, and the tooth - arranging grooves in adjacent rows are offset and complementary to each other.

14. The polycrystalline diamond radial bearing according to any one of claims 11-13, characterized in that, The polycrystalline diamond composite sheet includes a polycrystalline diamond sheet and a nickel - based filler metal wrapped outside the polycrystalline diamond sheet.

15. A polycrystalline diamond radial bearing, characterized in that, Manufactured by using the bearing surface hardening method according to any one of claims 1 - 10.

Images