Surface hardening method for universal joint of screw drill and related universal joint

Abstract

The invention discloses a surface hardening method for a universal joint of a screw drill and the related universal joint. The method comprises the following steps: carrying out thermal refining and finish machining on a universal joint blank subjected to rough turning to obtain a universal joint body; after the universal joint body is preheated, spot welding is conducted on the tungsten-cobalt alloy block wrapped by the nickel-based brazing filler metal to the wear-resisting contact face at one end of the universal joint body; spraying and welding nickel tungsten carbide powder and nickel-coated boron carbide composite powder on the wear-resistant contact surface to form a hardened layer on the wear-resistant contact surface; after cooling, the spray welding working face is ground to the designed size; checking pores of the spray welding working surface after grinding, filling the pores with composite powder of nickel tungsten carbide powder and nickel-coated boron carbide, and heating and melting to seal and fill the pores; and after cooling, the universal joint is finely ground to the designed size. The wear resistance and the impact fracture resistance of the universal joint are greatly improved, so that the universal joint can be matched with other screw drilling tool parts resistant to the high temperature of 350 DEG C to jointly form a screw drilling tool resistant to the high temperature of 350 DEG C.

Description

Technical Field

[0001] The invention relates to the technical field of drilling engineering equipment, and in particular to a surface hardening method for a screw drill universal joint and a related universal joint. Background Art

[0002] The universal joint of the screw drill is a key part of the screw drill transmission. The current manufacturing process usually adopts a heat treatment process of carburizing steel after long-term carburization and quenching and tempering to improve wear resistance. The long-term high-temperature heating of this heat treatment process causes the material structure to have coarse grains and poor impact resistance. The universal joint parts are prone to breakage, the corrosion and wear resistance is insufficient, and the service life is generally short, which is the shortcoming of the overall service life of the screw drill.

[0003] Universal joints manufactured with current technology cannot meet the needs of high-temperature drilling. The surface wear-resistant layer of universal joint parts treated by heat treatment process is carburized structure. When the carburized structure is exposed to an environment above 200℃ for more than a few hours, the carburized structure will undergo a structural transformation and the hardness of the carburized layer will begin to decrease. When the temperature exceeds 250℃, the hardness of the carburized layer will drop sharply, causing the wear resistance of the carburized layer to drop sharply, resulting in the universal joint being non-wear-resistant and breaking. Therefore, the universal joint parts currently produced by carburizing quenching and tempering surface hardening process cannot be used for a long time in a working environment above 200℃.

[0004] As drilling develops into deep and ultra-deep layers, well temperatures will mostly exceed 200°C, especially in geothermal drilling, which places higher demands on the temperature and wear resistance of downhole tools and screw drill bits. For example, it is generally required that universal joint parts still have sufficient strength, impact resistance, and wear resistance under long-term working conditions at well temperatures below 350°C, ensuring a sufficiently high service life and reliability. Summary of the invention

[0005] The inventors of the present invention have found that the universal joints currently produced on the market using existing manufacturing processes are generally unable to meet the high-temperature well conditions with a temperature exceeding 350°C.

[0006] In view of the above problems, the present invention is proposed to provide a surface hardening method for a screw drill universal joint and a related universal joint that overcomes the above problems or at least partially solves the above problems.

[0007] In a first aspect, an embodiment of the present invention provides a surface hardening method for a screw drill universal joint, comprising:

[0008] The rough-turned universal joint blank is subjected to quenching and tempering treatment and fine machining to obtain the universal joint body;

[0009] After preheating the universal joint body, spot welding a tungsten-cobalt alloy block wrapped with a nickel-based brazing filler metal to a wear-resistant contact surface at one end of the universal joint body;

[0010] The wear-resistant contact surface of the universal joint body after spot welding is spray-welded with nickel tungsten carbide powder and nickel-coated boron carbide composite powder to form a hardened layer on the wear-resistant contact surface;

[0011] After cooling, the spray-welded working surface is ground to the designed size;

[0012] Check the pores of the spray-welded working surface after grinding, fill the pores with nickel tungsten carbide powder and nickel-coated boron carbide composite powder, and heat and melt to seal the pores;

[0013] After cooling, the universal joint is finely ground to the designed size.

[0014] In one embodiment, the spot welding of the tungsten-cobalt alloy block wrapped with nickel-based brazing filler metal to the wear-resistant contact surface at one end of the universal joint body comprises:

[0015] A plurality of tungsten-cobalt alloy blocks wrapped with nickel-based brazing filler metals are spot welded one by one to the wear-resistant contact surface at one end of the universal joint, so that the tungsten-cobalt alloy blocks are fixed on the wear-resistant contact surface in a uniformly distributed tooth manner.

[0016] In one embodiment, the arrangement density of the plurality of tungsten-cobalt alloy blocks wrapped with nickel-based brazing fillers does not exceed 50%, and the arrangement density is the ratio of the total arrangement area of ​​the tungsten-cobalt alloy blocks wrapped with nickel-based brazing fillers to the wear-resistant contact surface area.

[0017] In one embodiment, the tungsten-cobalt alloy block wrapped with a nickel-based brazing filler metal is made of a YG8 alloy block wrapped with a nickel-based brazing filler metal;

[0018] The tungsten-cobalt alloy block wrapped with nickel-based brazing filler metal is spot welded to melt the bottom of the nickel-based brazing filler metal so as to be welded with the universal joint body, and the YG8 alloy block wrapped with nickel-based brazing filler metal is fixed on the wear-resistant contact surface of the universal joint.

[0019] In one embodiment, the wear-resistant contact surface of the universal joint body after spot welding is spray-welded with nickel tungsten carbide powder and nickel-coated boron carbide composite powder, including:

[0020] Heat the YG8 alloy block wrapped with nickel-based brazing filler metal to about 350°C;

[0021] A NiWC35 tungsten carbide dispersion spray welding powder with a thickness of about 0.12-0.15 mm is sprayed on the surface and surrounding of the YG8 alloy block wrapped with nickel-based brazing filler metal as a pre-protective layer;

[0022] Starting from one end of the spray-welding surface, the universal joint body is heated to 650° C.-700° C.;

[0023] Starting from one end of the spray welding surface, spray NiWC35 tungsten carbide dispersion spray welding powder and nickel-coated boron carbide composite powder in the gap of the YG8 alloy block wrapped by the nickel-based brazing filler metal to the height of the YG8 alloy block wrapped by the nickel-based brazing filler metal, and melt it to a molten mirror state, and repeat until reaching the end of the spray welding surface;

[0024] During the spray welding process, the YG8 alloy block is not exposed to the air, and the overall temperature of the universal joint body does not exceed 620°C.

[0025] In one embodiment, during spray welding, the powder feeding switch of the spray gun used is intermittently turned on to feed powder, the angle between the nozzle of the spray gun and the spray welding surface is 80-90°, the oxygen pressure used is 0.45-0.50MPa, and the acetylene pressure used is about 0.04MPa; the straight-line distance between the nozzle and the spray welding surface is about 20-25mm, and the nozzle movement speed is 5-8 meters / minute.

[0026] In one embodiment, the nickel tungsten carbide powder and the nickel-coated boron carbide composite powder are heated and melted by laser radiation to fill the pores, and the universal joint after filling the pores is placed in a box-type resistance furnace or lime wool at about 200°C for slow cooling until the universal joint is slowly cooled to room temperature and then taken out of the furnace.

[0027] In one embodiment, preheating the universal joint body includes:

[0028] The universal joint body is preheated in a box-type resistance furnace with an inert protective atmosphere. The inert protective gas is first introduced to exhaust the air in the furnace, and then the temperature is raised to 250-300°C and kept warm for 2 hours.

[0029] In one embodiment, the rough-turned universal joint blank is subjected to quenching and tempering treatment, including:

[0030] The universal joint body is heated to 860°C±5°C in a heating furnace, and then subjected to a heat preservation process at 860°C±5°C for 1.5 hours. After heat preservation, the universal joint body is transferred to a rapid quenching oil or water-based quenching medium for a rapid cooling process, so that the universal joint body is quickly cooled to room temperature;

[0031] Within 2 hours, the universal joint body is transferred back into the heating furnace and heated to 630℃±5℃ again. After being kept at 630℃±5℃ for 2 hours, it is quickly transferred into a cooling water tank with a water temperature below 30℃ to be cooled to room temperature.

[0032] In a second aspect, an embodiment of the present invention provides a universal joint for a screw drill, wherein the universal joint is made by the surface hardening method of the screw drill universal joint as described above.

[0033] The beneficial effects of the above technical solution provided by the embodiment of the present invention include at least:

[0034] The surface hardening method of the screw drill universal joint and the related universal joint provided by the embodiment of the present invention abandon the traditional method of improving wear resistance by carburizing carburized steel, spot weld the tungsten-cobalt alloy block wrapped with nickel-based brazing filler metal to the wear-resistant contact surface, and then spray weld the nickel tungsten carbide powder and the composite powder of nickel-coated boron carbide to form a hardened layer on the wear-resistant contact surface, which has high temperature resistance, corrosion resistance and strength. The screw drill universal joint treated by the surface hardening method provided by the embodiment of the present invention can avoid the problem of rapid softening of the surface hardened layer when the working condition exceeds 250°C, and overcome the problem of coarse grains and easy fracture of the traditional universal joint matrix material after long-term high-temperature carburizing treatment. It can be matched with other screw drill parts that are resistant to 350°C, and can form a 350°C resistant screw drill together, which greatly improves the wear resistance and impact fracture resistance of the universal joint in the screw drill.

[0035] The embodiments of the present invention provide a universal joint with a higher wear resistance and a longer service life for screw drill tools in high-temperature and ultra-high-temperature well exploration and development, and have broad application prospects in the field of ultra-deep well exploration and development.

[0036] It can be further promoted and applied to long-life screw drilling tools, which can greatly increase the service life of the long-life screw and greatly improve the efficiency of drilling operations.

[0037] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.

[0038] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying 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 of the present invention. In the accompanying drawings:

[0040] Figure 1A It is a schematic diagram of the overall structure of the universal joint in an embodiment of the present invention;

[0041] Figure 1B is a schematic diagram of the AA section of the universal joint in an embodiment of the present invention;

[0042] Figure 2 It is a schematic diagram of tooth arrangement of the AA cross-section in an embodiment of the present invention;

[0043] Figure 3 It is a development diagram of uniformly distributed teeth of a YG8 alloy block wrapped with a nickel-based brazing filler metal in an embodiment of the present invention;

[0044] Figure 4 A structural diagram of a YG8 alloy block wrapped with a nickel-based brazing filler metal in an embodiment of the present invention;

[0045] Figure 5 is a schematic cross-sectional view of a universal joint blank in an embodiment of the present invention;

[0046] Figure 6 It is a temperature curve diagram of the tempering process of the universal joint body in the embodiment of the present invention;

[0047] Figure 7 It is a partial schematic diagram of the spray welding of the YG8 alloy block wrapped with nickel-based brazing filler metal in an embodiment of the present invention. DETAILED DESCRIPTION

[0048] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying 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 to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0049] An embodiment of the present invention provides a surface hardening method for a universal joint of a screw drill, the method comprising the following steps:

[0050] S1, performing quenching and tempering treatment and fine machining on the rough-turned universal joint blank to obtain the universal joint body;

[0051] S2, after preheating the universal joint body, spot welding a tungsten-cobalt alloy block wrapped with a nickel-based brazing filler metal to a wear-resistant contact surface at one end of the universal joint body;

[0052] S3, spraying nickel tungsten carbide powder and nickel-coated boron carbide composite powder on the wear-resistant contact surface of the universal joint body after spot welding to form a hardened layer on the wear-resistant contact surface;

[0053] S4. After cooling, grind the spray-welded working surface to the designed size;

[0054] S5, check the pores of the spray-welded working surface after grinding, fill the pores with nickel tungsten carbide powder and nickel-coated boron carbide composite powder, and heat and melt to fill the pores;

[0055] S6. After cooling, grind the entire universal joint to the designed size.

[0056] In the above step S2, the tungsten-cobalt alloy block wrapped with nickel-based brazing filler metal is spot-welded to the wear-resistant contact surface at one end of the universal joint body. For example, a plurality of tungsten-cobalt alloy blocks wrapped with nickel-based brazing filler metal are spot-welded one by one to the wear-resistant contact surface at one end of the universal joint, so that the tungsten-cobalt alloy blocks are fixed on the wear-resistant contact surface in a uniformly distributed manner.

[0057] In one embodiment, the arrangement density of the plurality of tungsten-cobalt alloy blocks wrapped with nickel-based brazing filler metals does not exceed 50%, and the arrangement density is the ratio of the total arrangement area of ​​the tungsten-cobalt alloy blocks wrapped with nickel-based brazing filler metals to the wear-resistant contact surface area.

[0058] In one embodiment, the tungsten-cobalt alloy block wrapped with nickel-based brazing filler metal is made by a YG8 alloy block wrapped with nickel-based brazing filler metal;

[0059] The tungsten-cobalt alloy block wrapped with nickel-based brazing filler metal is spot welded to melt the bottom of the nickel-based brazing filler metal so as to be welded with the universal joint body, and the YG8 alloy block wrapped with nickel-based brazing filler metal is fixed on the wear-resistant contact surface of the universal joint.

[0060] Reference Figure 1A As shown, for example, the universal joint includes a wear-resistant contact surface 1-1, a universal joint body 1-2, and a tapered thread 1-3. Figure 1B yes Figure 1A In the cross-sectional view along the AA direction, the wear-resistant contact surface 1-1 is the welding surface of the spray-hardened layer, that is, the wear-resistant contact surface formed on the universal joint body 1-2. The wear-resistant contact surface 1-1 is composed of a YG8 alloy block 4-1 wrapped with a nickel-based brazing filler metal and a composite powder 2-3 of molten NiWC35 tungsten carbide dispersion spray-welding powder and trace nickel-coated boron carbide, and is the wear-resistant working surface of the universal joint.

[0061] Figure 2 for Figure 1A The tooth arrangement schematic diagram of the AA section view is composed of a YG8 alloy block 4-1 wrapped with a uniform nickel-based brazing filler metal, a body contact surface 4-2, and a universal joint body 1-2. That is, the YG8 alloy block 4-1 wrapped with a nickel-based brazing filler metal is spot-welded to the surface of the body contact surface 4-2 to form a distributed tooth arrangement.

[0062] Figure 3 for Figure 2 The nickel-based brazing filler metal-wrapped YG8 alloy block 4-1 is uniformly distributed and expanded. It is composed of a nickel-based brazing filler metal-wrapped YG8 alloy block 4-1 and a body contact surface 4-2. The nickel-based brazing filler metal-wrapped YG8 alloy block 4-1 is uniformly fixed on the surface of the body contact surface 4-2 by spot welding.

[0063] Figure 4 The structure diagram of the YG8 alloy block 4-1 wrapped with nickel-based brazing filler metal is shown in FIG. It is composed of a YG8 alloy block 5-2 and a nickel-based brazing filler metal 5-1. The YG8 alloy block 4-1 wrapped with nickel-based brazing filler metal is Figure 3 During the spot welding of the tooth pattern, the bottom part of the nickel-based solder 5-1 is melted and welded to the body contact surface 4-2, so that the YG8 alloy block 4-1 wrapped by the nickel-based solder is fixed on the surface of the body contact surface 4-2.

[0064] In one embodiment, the step S3 of spraying the nickel tungsten carbide powder and the nickel-coated boron carbide composite powder on the wear-resistant contact surface of the universal joint body after spot welding is specifically implemented by the following process:

[0065] Heat the YG8 alloy block wrapped with nickel-based brazing filler metal to about 350°C;

[0066] A NiWC35 tungsten carbide dispersion spray welding powder with a thickness of about 0.12-0.15 mm is sprayed on the surface and surrounding of the YG8 alloy block wrapped with nickel-based brazing filler metal as a pre-protective layer;

[0067] Starting from one end of the spray-welding surface, the universal joint body is heated to 650° C.-700° C.;

[0068] Starting from one end of the spray welding surface, spray NiWC35 tungsten carbide dispersion spray welding powder and nickel-coated boron carbide composite powder in the gap of the YG8 alloy block wrapped by the nickel-based brazing filler metal to the height of the YG8 alloy block wrapped by the nickel-based brazing filler metal, and melt it to a molten mirror state, and repeat until reaching the end of the spray welding surface;

[0069] During the spray welding process, the YG8 alloy block is not exposed to the air, and the overall temperature of the universal joint body does not exceed 620°C.

[0070] Figure 4 The structure diagram of the YG8 alloy block 4-1 wrapped with nickel-based brazing filler metal is shown in FIG. It is composed of a YG8 alloy block 5-2 and a nickel-based brazing filler metal 5-1. The YG8 alloy block 4-1 wrapped with nickel-based brazing filler metal is Figure 3 During the spot welding of the tooth pattern, the bottom part of the nickel-based solder 5-1 is melted and welded to the body contact surface 4-2, so that the YG8 alloy block 4-1 wrapped by the nickel-based solder is fixed on the surface of the body contact surface 4-2.

[0071] In one embodiment, during spray welding, the powder feeding switch of the spray gun used is intermittently turned on to feed powder, the angle between the nozzle of the spray gun and the spray welding surface is 80-90°, the oxygen pressure used is 0.45-0.50MPa, and the acetylene pressure used is about 0.04MPa; the straight-line distance between the nozzle and the spray welding surface is about 20-25mm, and the nozzle movement speed is 5-8 meters / minute.

[0072] In one embodiment, in the above step S5, the nickel tungsten carbide powder and the nickel-coated boron carbide composite powder are heated and melted by laser radiation to fill the pores, and the universal joint after filling the pores is placed in a box-type resistance furnace or lime wool at about 200°C for slow cooling until the universal joint is slowly cooled to room temperature and then taken out of the furnace.

[0073] In one embodiment, in the above step S1, preheating the universal joint body can be achieved in the following manner:

[0074] The universal joint body is preheated in a box-type resistance furnace with an inert protective atmosphere. The inert protective gas is first introduced to exhaust the air in the furnace, and then the temperature is raised to 250-300°C and kept warm for 2 hours.

[0075] In one embodiment, the rough-turned universal joint blank is subjected to quenching and tempering treatment, which can be specifically achieved in the following manner:

[0076] The universal joint body is heated to 860°C±5°C in a heating furnace, and then subjected to a heat preservation process at 860°C±5°C for 1.5 hours. After heat preservation, the universal joint body is transferred to a rapid quenching oil or water-based quenching medium for a rapid cooling process, so that the universal joint body is quickly cooled to room temperature;

[0077] Within 2 hours, the universal joint body is transferred back into the heating furnace and heated to 630℃±5℃ again. After being kept at 630℃±5℃ for 2 hours, it is quickly transferred into a cooling water tank with a water temperature below 30℃ to be cooled to room temperature.

[0078] For example, the substrate is made of high-strength steel containing alloys such as chromium, nickel, and molybdenum, and is subjected to quenching and tempering treatment to obtain sufficient mechanical properties and strength of the substrate. A YG8 alloy block wrapped with a nickel-based brazing filler metal with a side length of 10mm×10mm and a thickness of about 1.6mm is evenly distributed on the surface of the friction working surface, which accounts for about 50% of the total area. NiWC35 tungsten carbide dispersion spray welding powder and a trace amount of nickel-coated boron carbide composite powder are sprayed around the gaps of the YG8 alloy block wrapped with nickel-based brazing filler metal to harden the gaps around the YG8 alloy block wrapped with nickel-based brazing filler metal. During the process, the overall temperature of the substrate is strictly controlled not to exceed the tempering temperature during the quenching and tempering treatment of the substrate, so as to ensure that the mechanical properties and strength of the substrate are not reduced while obtaining a wear-resistant and corrosion-resistant wear-resistant hardened surface. It is suitable for 350℃ screw drill tools, and greatly improves the wear resistance of the universal joint without reducing the overall impact resistance of the steel substrate. The purpose of the embodiments of the present invention is to significantly increase the service life of the universal joint of the screw drill, thereby significantly increasing the overall service life of the screw drill, and improving the working efficiency of the screw drill used in high-temperature and complex working conditions.

[0079] Embodiment 1:

[0080] The process flow of universal joint processing provided by the first embodiment of the invention is as follows:

[0081] 5.1. Rough turning of the main body: Rough turning of the universal joint blank Figure 5 Shape shown.

[0082] 5.2. Body quenching and tempering treatment.

[0083] Description of the quenching and tempering process of the universal joint body 1-2 blank:

[0084] High strength universal joint body containing chromium, nickel, molybdenum and other alloys 1-2 Figure 6The high temperature heating furnace shown in the figure is heated to 860℃±5℃ through the process (3-1), and the internal structure of the universal joint body 1-2 is fully austenitized through the process (3-2) of 860℃±5℃ and 1.5 hours of heat preservation. After that, it is quickly transferred to the rapid quenching oil or water-based quenching medium for rapid cooling process (3-3), so that the universal joint body 1-2 is quickly cooled to room temperature, so that the internal structure of the steel is transformed from austenite to martensite to the greatest extent. Thereafter, it is transferred to the tempering furnace within a maximum of 2 hours, heated to 630℃±5℃ through process (3-4), and after the heat preservation process (3-5) of 630℃±5℃ for 2 hours, the martensite structure is transformed as completely as possible into the troostite structure, and then it is quickly transferred to the cooling water tank with a water temperature below 30℃ for process (3-6) to cool to room temperature, so as to reduce the segregation of impurities in the alloy at the grain boundary and better improve the impact toughness and strength of the workpiece.

[0085] 5.3. Finishing: The universal joint body is machined into Figure 1A Shape shown.

[0086] 5.4. Surface hardening processing.

[0087] 5.4.1. Degreasing and degreasing before welding: The surface of the universal joint body 1-2 is strictly degreased and degreased before spray welding. 5.4.2. Preheating before welding: Use a box-type resistance furnace with an inert protective atmosphere to preheat the universal joint body 1-2. During operation, first introduce inert protective gas to exhaust the air in the furnace, then raise the temperature to 250-300℃ and keep it warm for 2 hours.

[0088] 5.4.3. Spot welding of cemented carbide: After the heat preservation, take out the universal joint body 1-2 from the box-type resistance furnace with inert protective atmosphere, and quickly transfer it to the welding operation station. Figure 3 The spot welding is performed in a uniformly distributed tooth manner as shown. The spot welding current is 750-850A, and the YG8 alloy blocks 4-1 wrapped with nickel-based brazing filler metal are spot welded one by one on the body contact surface 4-2.

[0089] 5.4.4、Complete as Figure 2 and Figure 3 After spot welding the teeth, spray welding of NiWC35 tungsten carbide dispersion type spray welding powder is carried out.

[0090] 5.4.4.1. Spray pre-protective layer.

[0091] Add NiWC35 tungsten carbide dispersion type spray welding powder 6-1 into the powder tank of an oxygen-acetylene flame spray gun with an alloyed powder tank structure, and adjust the flame to a neutral flame.

[0092] The substrate surrounding the YG8 alloy block 4-1 wrapped with nickel-based brazing filler metal is preheated to about 350°C.

[0093] Oxygen pressure is 0.55-0.60MPa, acetylene pressure is 0.05-0.06MPa, the angle between the spray gun nozzle and the spray welding surface is 80-90°, the straight-line distance between the nozzle and the spray welding surface is about 170-180mm, and the nozzle moving speed is 6-8 meters / minute. A layer of NiWC35 tungsten carbide dispersion spray welding powder 6-1 with a thickness of 0.12-0.15mm is sprayed on the surface and surrounding of the YG8 alloy block 4-1 wrapped with nickel-based brazing filler metal, and the YG8 alloy block 4-1 wrapped with nickel-based brazing filler metal is tightly wrapped and firmly welded to the body contact surface 4-2.

[0094] Figure 7 It is a partial schematic diagram of the spray welding of the YG8 alloy block 4-1 wrapped with nickel-based brazing filler metal, which includes the universal joint body 1-2, the YG8 alloy block 4-1 wrapped with nickel-based brazing filler metal, the body contact surface 4-2, and the NiWC35 tungsten carbide dispersion type spray welding powder 6-1.

[0095] In the above embodiment:

[0096] 1) During the spraying process, the YG8 alloy block 4-1 wrapped with the nickel-based brazing filler metal must be tightly wrapped to avoid oxidation.

[0097] 2) During the spray welding process, the flame center position needs to be constantly moved to prevent the wrapped YG8 alloy block 5-2 from being exposed to the air and the universal joint body 1-2 from being locally overheated.

[0098] 3) During the operation, strictly control the overall temperature rise of the YG8 alloy block 5-2 and the universal joint body 1-2. The overall temperature of the universal joint body 1-2 shall not exceed 620°C, and strictly control the heating and cooling speed of the cemented carbide block to avoid excessive temperature difference between the inside and outside of the YG8 alloy block 5-2, which may cause cracks in the YG8 alloy block 5-2.

[0099] 5.4.4.2 Spray welding hardening layer;

[0100] The powder tank of the flame spray gun is replaced with NiWC35 tungsten carbide dispersion spray welding powder and a trace amount of nickel-coated boron carbide composite powder 2-3.

[0101] Starting from one end of the spray welding surface, heat the workpiece to about 650℃-700℃.

[0102] After that, adjust the flame to a softer neutral flame, intermittently open the powder feeding switch to feed powder, the distance between the nozzle and the spray welding surface is 20-30mm, and the gap of the alloy block is sprayed with NiWC35 tungsten carbide dispersion spray welding powder and a trace of nickel-coated boron carbide composite powder 2-3. Spray the NiWC35 tungsten carbide dispersion spray welding powder and a trace of nickel-coated boron carbide composite powder 2-3 to the height of the YG8 alloy block 4-1 wrapped with nickel-based brazing filler metal, and melt it to a molten mirror surface. At this time, the flame core should be immediately moved to the next part to continue spraying powder and melting powder, and repeat until the end of the spray welding surface is reached.

[0103] In the above embodiment:

[0104] 1) Ensure that the YG8 alloy block 5-2 is wrapped and sealed to avoid direct contact with air and oxidation.

[0105] 2) When spraying powder, the angle between the spray gun nozzle and the spray welding surface is 80-90°, the flame is adjusted to a softer neutral flame, the oxygen pressure is 0.45-0.50MPa, the acetylene pressure is about 0.04MPa, and the gas flow rate is slightly increased. The straight-line distance between the nozzle and the spray welding surface is about 20-25mm, and the nozzle moves at a speed of 5-8 meters / minute.

[0106] 3) It is necessary to strictly control the powder feeding amount of the spray gun and the thickness of the spray welding.

[0107] 4) During remelting, the straight-line distance between the nozzle and the spray-welding surface is 7-10mm. The remelting time should be as short as possible. After the molten mirror surface appears, move to the next part immediately and continue powder spraying and remelting.

[0108] 5) Reduce the temperature rise of the YG8 alloy block 5-2 and the substrate as much as possible.

[0109] 6) During the spray welding process, the flame center position is continuously moved to prevent local overheating of the YG8 alloy block 5-2 and the universal joint body 1-2, and the molten surface is continuously stirred to remove slag and gas.

[0110] 7) During the spraying process, the overall temperature of the universal joint body 1-2 shall not exceed 620°C.

[0111] 8) During the operation, the heating and cooling speed of the cemented carbide should be strictly controlled to avoid cracks caused by excessive temperature difference between the inside and outside of the YG8 alloy block 5-2.

[0112] 9) Pay attention to wind protection during operation.

[0113] 5.5. After spray welding is completed, quickly put it into a 200℃ box-type resistance furnace or lime wool for slow cooling.

[0114] 5.6. Slowly cool the workpiece until the temperature is below 200℃ and then take it out of the furnace for air cooling.

[0115] 5.7. Use a diamond grinding wheel to grind the spray-welded working surface of the workpiece to the designed size.

[0116] 5.8. Check the pores on the spray-welded surface after grinding.

[0117] 5.9. Fill the pores on the spray welding surface with 2-3% NiWC35 tungsten carbide dispersion spray welding powder and a trace amount of nickel-coated boron carbide composite powder.

[0118] 5.10. Heat and melt NiWC35 tungsten carbide dispersion spray welding powder and 2-3% of nickel-coated boron carbide composite powder by laser radiation to fill the pores, and quickly put the sealed workpiece into a 200°C box-type resistance furnace for slow cooling, and then take it out of the furnace after slow cooling to room temperature.

[0119] 5.11. Use a diamond grinding wheel to grind the sealing area of ​​the workpiece and the entire working surface to the designed size.

[0120] Embodiment 2:

[0121] The material of the universal joint body is 30CrNi2MoV, and the material composition is as follows (weight ratio): 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.

[0122] The universal joint processing process provided in the second embodiment of the invention is as follows:

[0123] 8.1. Rough turning of the body: Rough turning of the universal joint blank into Figure 5 Shape shown.

[0124] 8.2. Body quenching and tempering treatment:

[0125] After 860℃ insulation for 1.5 hours, the 50℃ water-based quenching medium is cooled to room temperature, and then immediately heated at 630℃ for 2 hours, and then quickly cooled to room temperature in water. The surface hardness of the universal joint body after 1-2 tempering is: 37-39HRC.

[0126] 8.3. Finishing: The universal joint body is machined into Figure 1A Shape shown.

[0127] 8.4. Surface hardening processing.

[0128] 8.4.1. Degreasing before welding: Clean the universal joint body with 1-290℃ alkaline water for 30 minutes and then dry it for 15 minutes.

[0129] 8.4.2 Preheating before welding: Use a box-type resistance furnace with nitrogen protective atmosphere to preheat the universal joint body 1-2. During operation, first introduce nitrogen to evacuate the air in the furnace, then raise the temperature to 300℃ and keep it warm for 2 hours.

[0130] 8.4.3. Spot welding of cemented carbide: After the heat preservation, take out the universal joint body 1-2 from the nitrogen atmosphere protection box-type resistance furnace and quickly transfer it to the welding operation station. Figure 3The spot welding is performed in a uniformly distributed tooth manner as shown. The spot welding current is 800A, and the YG8 alloy blocks 4-1 wrapped with nickel-based brazing filler metal are spot welded one by one on the contact surface 4-2 of the body, and the tooth distribution occupies about 40% of the surface area of ​​the hardened surface.

[0131] 8.4.4. Implement spray welding of NiWC35 tungsten carbide dispersion type spray welding powder.

[0132] 8.4.4.1. Spray pre-protective layer.

[0133] Add NiWC35 tungsten carbide dispersion type spray welding powder 6-1 into the powder tank of an oxygen-acetylene flame spray gun with an alloyed powder tank structure, and adjust the flame to a neutral flame.

[0134] The substrate surrounding the YG8 alloy block 4-1 wrapped with nickel-based brazing filler metal is preheated to about 350°C.

[0135] The oxygen pressure is 0.60MPa, the acetylene pressure is 0.05MPa, the angle between the spray gun nozzle and the spray welding surface is 85°, the straight-line distance between the nozzle and the spray welding surface is about 175mm, and the nozzle moving speed is 6-8 meters / minute. A layer of NiWC35 tungsten carbide dispersion spray welding powder 6-1 with a thickness of about 0.15mm is sprayed on the surface and surroundings of the YG8 alloy block 4-1 wrapped with nickel-based brazing filler metal, and the YG8 alloy block 4-1 wrapped with nickel-based brazing filler metal is tightly wrapped and firmly welded to the body contact surface 4-2.

[0136] 8.4.4.2 Spray-welded hardened layer.

[0137] The powder tank of the flame spray gun is replaced with NiWC35 tungsten carbide dispersion spray welding powder and a trace amount of nickel-coated boron carbide composite powder 2-3.

[0138] The workpiece is heated from one end of the spray welding surface to about 700°C.

[0139] The angle between the spray gun nozzle and the spray welding surface is about 85°, the flame is adjusted to a softer neutral flame, the oxygen pressure is 0.50MPa, the acetylene pressure is about 0.04MPa, and the gas flow rate is slightly increased. The straight-line distance between the nozzle and the spray welding surface is about 20mm, and the nozzle moving speed is about 8 meters / minute.

[0140] Intermittently open the powder feeding switch to feed powder, and spray-weld the gap of the alloy block with NiWC35 tungsten carbide dispersion spray-welding powder and a trace of nickel-coated boron carbide composite powder 2-3. Spray-weld NiWC35 tungsten carbide dispersion spray-welding powder and a trace of nickel-coated boron carbide composite powder 2-3 to the height of the YG8 alloy block 4-1 wrapped with nickel-based brazing filler metal, and melt it to a molten mirror surface. At this time, the flame core should be immediately moved to the next part to continue spraying powder, and continue to melt the powder, and repeat until the end of the spray-welding surface. During the spray-welding process, the overall temperature of the universal joint body 1-2 is strictly controlled not to exceed 620°C, and the YG8 alloy block 5-2 must not be directly exposed to the air.

[0141] 8.5. After spray welding is completed, quickly put it into a 200℃ box-type resistance furnace or lime wool for slow cooling.

[0142] 8.6. Slowly cool the workpiece until the temperature is below 200℃ and then take it out of the furnace and air cool it.

[0143] 8.7. Use a diamond grinding wheel to grind the spray-welded working surface of the workpiece to the designed size.

[0144] 8.8. Check the pores on the spray-welded surface after grinding.

[0145] 8.9. Fill 2-3 of NiWC35 tungsten carbide dispersion spray welding powder and trace nickel-coated boron carbide composite powder into the pores on the spray welding surface.

[0146] 8.10. Use 1800W laser power and 2mm beam diameter laser radiation to heat NiWC35 tungsten carbide dispersion spray welding powder and trace nickel-coated boron carbide composite powder 2-3 until it melts and fills the pores, and then quickly put the sealed workpiece into a 200℃ box-type resistance furnace for slow cooling, and then take it out of the furnace after slow cooling to room temperature.

[0147] 8.11. Use a diamond grinding wheel to grind the sealing area of ​​the workpiece and the entire working surface to the designed size.

[0148] In the above embodiment:

[0149] 1. Under the premise of meeting the wear resistance requirements, the tungsten carbide spray-welded layer should be as thin as possible to reduce the thermal impact of the thermal spray-welding process on the universal joint body. Generally, the final spray-welded layer of 1.8mm can meet the wear resistance requirements.

[0150] 2. During the spray welding process, ensure that the YG8 alloy block 5-2 is not exposed to the air. Once the YG8 alloy block 5-2 is exposed to the air, it will cause surface decarburization or fragmentation.

[0151] 3. The arrangement density of the YG8 alloy block 4-1 wrapped with nickel-based brazing filler metal should not exceed 50%. If it exceeds 50%, the heat affected zone of the universal joint body 1-2 is likely to expand, which will reduce the strength of the universal joint body 1-2, reduce the impact resistance of the universal joint body 1-2, and increase the risk of fragmentation of the YG8 alloy block 5-2.

[0152] 4. The remelting time of the hardened layer should be as short as possible. After the molten mirror surface appears, it is necessary to move to the next part immediately and continue powder spraying and remelting. Otherwise, the remelting part will be overheated, reducing the strength of the universal joint body 1-2 and the impact resistance of the universal joint body 1-2, while increasing the risk of fragmentation of the YG8 alloy block 5-2.

[0153] The surface hardening method of the screw drill universal joint and the related universal joint provided by the embodiment of the present invention abandon the traditional method of improving wear resistance by carburizing steel, spot weld the tungsten-cobalt alloy block wrapped with nickel-based brazing filler metal to the wear-resistant contact surface, and then spray weld the nickel tungsten carbide powder and the composite powder of nickel-coated boron carbide to form a hardened layer on the wear-resistant contact surface, which has high temperature resistance, corrosion resistance and strength. The screw drill universal joint treated by the surface hardening method provided by the embodiment of the present invention can avoid the problem of rapid softening of the surface hardened layer when the working condition exceeds 250°C, and overcome the problem of coarse grains and easy fracture of the traditional universal joint matrix material after long-term high-temperature carburizing treatment. It can be matched with other screw drill parts that are resistant to 350°C, and can form a screw drill that is resistant to 350°C, which greatly improves the wear resistance and impact fracture resistance of the universal joint.

[0154] The embodiments of the present invention provide a universal joint with a higher wear resistance and a longer service life for screw drill tools in high-temperature and ultra-high-temperature well exploration and development, and have broad application prospects in the field of ultra-deep well exploration and development.

[0155] It can be further promoted and applied to long-life screw drilling tools, which can greatly increase the service life of the long-life screw and greatly improve the efficiency of drilling operations.

[0156] The trial product was tempered at 620℃. Theoretically, the overall strength of the universal joint body will not decrease below 630℃. The tungsten carbide spray-welded layer will not fail or soften below 350℃, which fully meets the requirements of screw drilling tools in high-temperature well conditions below 350℃.

[0157] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A surface hardening method for a universal joint of a screw drill, characterized in that: include: The rough-turned universal joint blank is subjected to quenching and tempering treatment and fine machining to obtain the universal joint body; After preheating the universal joint body, spot welding a tungsten-cobalt alloy block wrapped with a nickel-based brazing filler metal to a wear-resistant contact surface at one end of the universal joint body; The wear-resistant contact surface of the universal joint body after spot welding is spray-welded with nickel tungsten carbide powder and nickel-coated boron carbide composite powder to form a hardened layer on the wear-resistant contact surface; After cooling, the spray-welded working surface is ground to the designed size; Check the pores of the spray-welded working surface after grinding, fill the pores with nickel tungsten carbide powder and nickel-coated boron carbide composite powder, and heat and melt to seal the pores; After cooling, the universal joint is finely ground to the designed size.

2. The method according to claim 1, characterized in that The step of spot welding the tungsten-cobalt alloy block wrapped with nickel-based brazing filler metal to the wear-resistant contact surface at one end of the universal joint body comprises: A plurality of tungsten-cobalt alloy blocks wrapped with nickel-based brazing filler metals are spot welded one by one to the wear-resistant contact surface at one end of the universal joint, so that the tungsten-cobalt alloy blocks are fixed on the wear-resistant contact surface in a uniformly distributed tooth manner.

3. The method according to claim 2, characterized in that The arrangement density of the plurality of tungsten-cobalt alloy blocks wrapped with nickel-based brazing filler metals does not exceed 50%, and the arrangement density is the ratio of the total arrangement area of ​​the tungsten-cobalt alloy blocks wrapped with nickel-based brazing filler metals to the wear-resistant contact surface area.

4. The method according to claim 2, characterized in that The tungsten-cobalt alloy block wrapped with a nickel-based brazing filler metal is made by a YG8 alloy block wrapped with a nickel-based brazing filler metal; The tungsten-cobalt alloy block wrapped with nickel-based brazing filler metal is spot welded to melt the bottom of the nickel-based brazing filler metal so as to be welded with the universal joint body, and the YG8 alloy block wrapped with nickel-based brazing filler metal is fixed on the wear-resistant contact surface of the universal joint.

5. The method according to claim 4, characterized in that The wear-resistant contact surface of the universal joint body after spot welding is sprayed with nickel tungsten carbide powder and nickel-coated boron carbide composite powder, including: Heat the YG8 alloy block wrapped with nickel-based brazing filler metal to about 350°C; A NiWC35 tungsten carbide dispersion spray welding powder with a thickness of about 0.12-0.15 mm is sprayed on the surface and surrounding of the YG8 alloy block wrapped with nickel-based brazing filler metal as a pre-protective layer; Starting from one end of the spray-welding surface, the universal joint body is heated to 650° C.-700° C.; Starting from one end of the spray welding surface, spray NiWC35 tungsten carbide dispersion spray welding powder and nickel-coated boron carbide composite powder in the gap of the YG8 alloy block wrapped by the nickel-based brazing filler metal to the height of the YG8 alloy block wrapped by the nickel-based brazing filler metal, and melt it to a molten mirror state, and repeat until reaching the end of the spray welding surface; During the spray welding process, the YG8 alloy block is not exposed to the air, and the overall temperature of the universal joint body does not exceed 620°C.

6. The method according to claim 5, characterized in that During spray welding, the powder feeding switch of the spray gun used is intermittently turned on to feed powder. The angle between the nozzle of the spray gun and the spray welding surface is 80-90°, the oxygen pressure used is 0.45-0.50MPa, and the acetylene pressure used is about 0.04MPa; the straight-line distance between the nozzle and the spray welding surface is about 20-25mm, and the nozzle movement speed is 5-8 meters / minute.

7. The method according to claim 1, characterized in that The nickel tungsten carbide powder and the nickel-coated boron carbide composite powder are heated and melted by laser radiation to fill the pores, and the universal joint after filling the pores is placed in a box-type resistance furnace or lime wool at about 200° C. for slow cooling until the universal joint is slowly cooled to room temperature and then taken out of the furnace.

8. The method according to any one of claims 1 to 7, characterized in that: The preheating of the universal joint body comprises: The universal joint body is preheated in a box-type resistance furnace with an inert protective atmosphere. The inert protective gas is first introduced to exhaust the air in the furnace, and then the temperature is raised to 250-300°C and kept warm for 2 hours.

9. The method according to any one of claims 1 to 7, characterized in that: The rough-turned universal joint blank is subjected to quenching and tempering treatment, including: The universal joint body is heated to 860°C±5°C in a heating furnace, and then subjected to a heat preservation process at 860°C±5°C for 1.5 hours. After heat preservation, the universal joint body is transferred to a rapid quenching oil or water-based quenching medium for a rapid cooling process, so that the universal joint body is quickly cooled to room temperature; Within 2 hours, the universal joint body is transferred back into the heating furnace and heated to 630℃±5℃ again. After being kept at 630℃±5℃ for 2 hours, it is quickly transferred into a cooling water tank with a water temperature below 30℃ to be cooled to room temperature.

10. A universal joint for a screw drill, characterized in that: The universal joint is made by the surface hardening method of the screw drill universal joint as described in any one of claims 1-9.

Images