A wind turbine main shaft bearing ring and its hot working method

Abstract

This invention relates to the field of alloy heat treatment and bearing manufacturing technology, specifically a wind turbine main shaft bearing raceway and its heat treatment method. The heat treatment method includes smelting, forging, quenching and tempering, precision machining, and raceway surface quenching. The quenching structure includes two sets of heaters on the left and right sides, and two sets of water spray boxes on the left and right sides. This invention uses eight heating heads and four independent cooling water boxes to quench the raceway surface of the bearing raceway after smelting, forging, quenching and tempering, and precision machining. By strictly controlling the distance between each component, the heating power and quenching speed in different areas are coordinated and adjusted. After heat treatment, the annular raceway of the bearing raceway achieves high surface hardness, uniform hardened layer depth, fine microstructure, and grain size, solving the problems of soft bands and areas, and unqualified microstructure and grain size on the raceway surface of bearing raceways after traditional surface quenching techniques.

Description

Technical Field

[0001] This invention relates to the fields of alloy heat treatment and bearing manufacturing technology, specifically a wind turbine main shaft bearing ring and its heat treatment method. Background Technology

[0002] Wind turbines convert wind energy into mechanical work, which drives a rotor to rotate and ultimately outputs alternating current (AC). In recent years, as wind turbines have developed towards higher power outputs, the structural dimensions of wind turbine main shaft bearings have continuously increased. Due to limitations in material costs and heat treatment equipment, induction hardening has replaced deep carburizing heat treatment and overall quenching of high-carbon chromium bearing steel with the development trend of large-size bearings. However, wind turbine main shaft bearings operate in harsh environments, requiring the entire annular raceway surface of the bearing raceways to have high surface hardness, uniform hardened layer depth, fine microstructure, and grain size. Traditional induction hardening creates low-hardness, shallow-depth soft zones at the joints at the beginning and end of the bearing raceways, known as soft bands. During bearing use, these soft band areas are prone to wear, becoming weak points for crack formation and propagation, failing to meet the requirements of wind turbine main shaft bearings. Summary of the Invention

[0003] To address the above problems, this invention provides a wind turbine main shaft bearing race and its hot processing method. After hot processing, the annular raceway of the bearing race can obtain high surface hardness (hardness ≥ 58HRC), uniform hardened layer depth, fine microstructure and grain size, which solves the problems of soft bands and soft areas on the surface of the bearing raceway after quenching by traditional surface hardening technology, as well as unqualified microstructure and grain size.

[0004] This invention is specifically achieved through the following technical solution: a hot working method for wind turbine main shaft bearing rings proposed by this invention includes the following steps: S1. Material smelting: According to the designed composition ratio, the raw materials are taken and smelted into continuous casting billets of the required specifications through electric furnace / converter primary smelting, LF refining, VD / RH vacuum degassing, continuous casting, and slow cooling annealing. S2. The continuously cast billet obtained in step S1 is forged. The forging process includes billet preparation, punching, and rolling. After forging, a ring forging is obtained. S3. The ring forging obtained in step S2 is subjected to quenching and tempering treatment, which includes quenching and tempering. S4. Perform precision machining on the tempered bearing rings; S5. The bearing rings obtained in step S4 are subjected to raceway surface quenching. The quenching structure includes two sets of heaters on the left and right sides, and two sets of water spray boxes on the left and right sides. The left heater includes left heating head I, left heating head II, left heating head III, and left heating head IV arranged in sequence. The two water spray boxes on the left side include a left main water spray box and a left auxiliary water spray box, with the left main water spray box located between the left heating head IV and the left auxiliary water spray box. The right heater includes right heating head I, right heating head II, right heating head III, and right heating head IV arranged in sequence. The two water spray boxes on the right side include a right main water spray box and a right auxiliary water spray box, with the right main water spray box... The box is located between the right heating head IV and the right auxiliary water spray box; in the initial state, the eight heating heads and two main water spray boxes on the left and right sides are symmetrically arranged around the raceway of the bearing ring to be heated. The left heating head I, left heating head II, left heating head III, left heating head IV, and left main water spray box are respectively positioned and symmetrically arranged with the right heating head I, right heating head II, right heating head III, right heating head IV, and right main water spray box. The left auxiliary water spray box and the right auxiliary water spray box are stacked and staggered behind the left and right main water spray boxes; the steps for surface quenching the bearing ring raceway using the above quenching structure include: S5.1, First Stage: At the beginning of quenching, only the left heating head III, left heating head IV, right heating head III, and right heating head IV are used to heat the bearing raceway. The left and right sets of heaters and the left and right sets of water spray boxes remain stationary. The bearing raceway rotates alternately left and right around the left heating head III, left heating head IV, right heating head III, and right heating head IV. The rotation distance on each side is 80-120mm, and the number of rotations is 3-6. After the rotation heating reaches the temperature of the heated part of the bearing raceway at 870-890℃, the bearing raceway returns to the starting position and stops rotating. Then, the second stage begins. S5.2, Second Stage: With the bearing ring stationary, the four heating heads and two water spray boxes on the left and the four heating heads and two water spray boxes on the right simultaneously rotate in opposite directions along the circumference of the bearing ring from their initial positions. The four heating heads on the left and four on the right simultaneously activate heating, and at the same time, the left and right main water spray boxes begin spray cooling. When the left and right auxiliary water spray boxes move between the left and right main water spray boxes and the distance between the left and right auxiliary water spray boxes is 30-50mm, the left and right auxiliary water spray boxes begin spray cooling. The two side spray water boxes and the two right side spray water boxes cover the entire quenching surface and prevent water backflow. The rotation speed of the eight heating heads on the left and right sides and the four spray water boxes on the left and right sides is 60-90 mm / min. The heating power of the left heating head I and the left heating head II is always higher than that of the left heating head III and the left heating head IV. The heating power of the right heating head I and the right heating head II is always higher than that of the right heating head III and the right heating head IV. When the left and right sets of heaters rotate to a distance of 2-5 mm between the left heating head I and the right heating head I, the left heating head I and the left heating head II stop heating and exit the raceway position. The raceway surface quenching enters the third stage. S5.3, Third Stage: After the left heating heads I and II stop heating and exit the raceway position, the left heating heads III, IV, I, II, III, and IV continue to rotate and heat in the direction of rotation of the second stage. Simultaneously, the two water spray boxes on the left and two on the right continue to rotate and spray water in the direction of rotation of the second stage. The rotation speed of the left heating heads III, IV, I, II, III, and IV, the two water spray boxes on the left, and the two water spray boxes on the right all decrease to 35-50. While maintaining the same rotation speed, the heating power of the left heating head III, left heating head IV, right heating head III, and right heating head IV is reduced by 4-8% compared to the corresponding heating head in the second stage, while the heating power of the right heating head I and right heating head II is increased by 8-12% compared to the corresponding heating head in the second stage. This process continues until the distance between the right heating head I and the left heating head III is 4-6mm. Then, the right heating head I and right heating head II stop heating and exit the raceway position. The raceway surface quenching then enters the fourth stage. S5.4, Fourth Stage: After the right heating heads I and II stop heating and exit the raceway position, the left heating heads III, IV, III, and IV continue to rotate and heat in the direction of rotation of the second stage. At the same time, the two water spray boxes on the left and two on the right continue to rotate and spray water in the direction of rotation of the second stage. The rotation speed of the remaining four heating heads and the two water spray boxes on the left and right is reduced to 20-30 mm / min and they are kept at the same rotation speed. The heating power of the left heating heads III, IV, III, and IV is reduced by 3-5% compared with the corresponding heating heads in the third stage. Heating stops when the distance between the left heating head III and the right heating head III is 1-3 mm. All heating heads exit the raceway position within 2 seconds. At the same time, the tail water spray box is turned on for direct spray cooling. The spray surface of the tail water spray box is large enough to cover all uncooled parts of the final heating area. S5.5 After cooling, the workpiece is tempered within 8 hours at a temperature of 170±10℃ and a holding time of 4-6 hours. After holding, the workpiece is removed from the furnace and air-cooled to room temperature to obtain the wind turbine main shaft bearing ring.

[0005] In the aforementioned hot working method for wind turbine main shaft bearing rings, in step S1, the chemical composition of the wind turbine main shaft bearing ring material, by weight percentage, includes: C: 0.43-0.55%, Si: 0.15-0.45%, Mn: 0.50-0.90%, Cr: 0.90-1.30%, Mo: 0.15-0.40%, Ni: 0.35-0.65%, V: 0.03-0.09%, Al: 0.010-0.050%, O≤15ppm, Ca≤12ppm, Ti≤25ppm, H≤2ppm, with the balance being Fe and unavoidable impurities.

[0006] The aforementioned hot working method for the bearing ring of the wind turbine main shaft includes the following forging process: the continuously cast billet obtained in step S1 is placed in a heating furnace and heated to 800°C at a rate of ≤100°C / h, held for 2 hours, then heated to 1150-1200°C at a rate of ≤120°C / h, held for 3-5 hours, and the heated billet is subjected to three upsettings and two drawings; then punching is performed, the punched material is returned to the furnace, and heated again to 1150-1180°C at a rate of ≤120°C / h, and then subjected to initial rolling and final rolling on a ring rolling mill. After the final rolling is completed, the material temperature is cooled to 300°C in a box-type slow cooling device before it drops to 800°C, and then it is removed from the box and air-cooled to room temperature to obtain the ring forging.

[0007] In the aforementioned hot working method for the bearing rings of the wind turbine main shaft, the punching is formed by a hollow guide punch with a conical inner hole and a cutting edge in one punching process. The end with the larger diameter of the conical inner hole of the hollow guide punch is defined as the tail of the punch. The wall thickness d of the hollow guide punch is 0.2-0.3 times the outer diameter D of the tail of the punch. The angle between the inclined surface of the conical inner hole and the vertical direction is 2-5°, and the angle between the outer inclined surface of the cutting edge and the vertical direction is 4-8°.

[0008] The aforementioned hot working method for the bearing rings of the wind turbine main shaft includes the following specific heat treatment process: heating the forged ring to 830-880℃, holding it at 1.2-1.5 min / mm according to the maximum wall thickness of the ring, removing the ring after holding, immersing it in water for cooling within ≤2 min, cooling it to 100-120℃, removing it from the water and air cooling it to room temperature, then heating the ring to 610-650℃, holding it at 2.5-3.0 min / mm according to the maximum wall thickness of the ring, removing it from the furnace and air cooling it to room temperature.

[0009] In the aforementioned hot working method for the bearing rings of the wind turbine main shaft, the widths of the left heating head I, left heating head II, left heating head III, right heating head I, right heating head II, and right heating head III are all 20-26mm, and the widths of the left heating head IV and right heating head IV are all 15-19mm.

[0010] In the aforementioned hot working method for the bearing rings of the wind turbine main shaft, the distances between left heating head I and left heating head II, left heating head III and left heating head IV, right heating head I and right heating head II, and right heating head III and right heating head IV are all 5-10mm, and the distances between left heating head II and left heating head III, and right heating head II and right heating head III are all 25-45mm; the distances between the left main water spray box and left heating head IV, and between the right main water spray box and right heating head IV are all 15-35mm. In the initial state, the distance between the left main water spray box and the right main water spray box is ≤35mm, and the left auxiliary water spray box and the right auxiliary water spray box are stacked and staggered behind the left main water spray box and the right main water spray box.

[0011] In the aforementioned hot working method for the bearing rings of the wind turbine main shaft, the heating power of the left heating head I and the left heating head II is 1.1-1.2 times that of the left heating head III and the left heating head IV, and the heating power of the right heating head I and the right heating head II is 1.1-1.2 times that of the right heating head III and the right heating head IV.

[0012] The aforementioned hot working method for wind turbine main shaft bearing raceways results in a final surface hardness of HRC 58-63 for the raceway.

[0013] The present invention also proposes a wind turbine main shaft bearing ring obtained by the above-mentioned hot working method. The chemical composition of the wind turbine main shaft bearing ring material by weight percentage includes: C: 0.43-0.55%, Si: 0.15-0.45%, Mn: 0.50-0.90%, Cr: 0.90-1.30%, Mo: 0.15-0.40%, Ni: 0.35-0.65%, V: 0.03-0.09%, Al: 0.010-0.050%, O≤15ppm, Ca≤12ppm, Ti≤25ppm, H≤2ppm, with the balance being Fe and unavoidable impurities.

[0014] Compared with the prior art, the present invention has at least the following advantages: (1) This invention significantly improves the stability of austenite in bearing materials through a multi-element synergistic alloying design of "Cr-Mo-Ni-Mn-V", strongly inhibits the transformation of pearlite and bainite, and makes the supercooled austenite more stable. The addition of trace amounts of V can form fine carbonitrides, pinning grain boundaries and preventing austenite grain growth. While improving hardenability, it can also effectively improve the toughness of the material. The slow cooling annealing process at ≥600℃ effectively avoids the generation of hydrogen-induced cracks and white spots in the continuously cast billet, providing defect-free billets for subsequent hot working.

[0015] (2) This invention uses a hollow guide punch with a tapered inner hole and a cutting edge to punch and form a hole in one step. Compared with the prior art, it achieves the comprehensive effects of reduced punching force, smooth chip removal, excellent cross-sectional quality, and long die life, solving the problem of one-time punching and forming of thick plates and high-strength materials. After the final rolling, the material is placed in a box-type slow cooling device before the temperature drops to 800℃ to prevent the formation of coarse or non-equilibrium structures that are harmful to toughness, and to uniformly refine the forging structure. During subsequent quenching and heating, austenitization is more uniform and the grains are easier to control, thereby obtaining an excellent quenched structure and improving the comprehensive mechanical properties of the final heat treatment. The water immersion time after quenching and heating is strictly controlled to be ≤2min, ensuring that the austenite is rapidly cooled to below the martensitic transformation temperature (Ms point), avoiding high-temperature and medium-temperature transformation, and ensuring that a high-hardness martensitic structure is obtained after quenching, so that the wind turbine main shaft bearing ring material obtains the required strength and wear resistance. The water temperature of the water inlet cooling system is precisely controlled at 100-120℃, which effectively controls thermal stress and deformation. At the same time, the residual heat accumulated inside the workpiece is used to give the brittle martensite that has been formed a slight "self-tempering", which reduces the brittleness and internal stress of the martensite and greatly reduces the risk of workpiece cracking.

[0016] (3) The bearing raceway surface quenching uses 8 heating heads and 4 independent cooling water boxes to form two sets of inductors. The distance between each component is strictly controlled, which can realize the coordinated adjustment of heating power and quenching speed in different areas. After the entire bearing raceway is quenched, a uniform hardened layer depth can be achieved. The quenching start only uses left heating head III, left heating head IV, right heating head III, and right heating head IV, which makes the starting action simple and easy to operate and keeps the quenching start fluctuation area to a minimum. During the quenching process, the heating power of left heating head I and left heating head II is strictly controlled to be 1.1-1.2 times that of left heating head III and left heating head IV, and the heating power of right heating head I and right heating head II is 1.1-1.2 times that of right heating head III and right heating head IV. First, the bearing raceway material is heated to above the austenitizing temperature quickly and uniformly by high power heating, and then "heat preservation" or "supplementary heating" is carried out by subsequent lower power heating, so as to ensure that the material austenitizes fully and uniformly. By precisely controlling the high-temperature dwell time and actual peak temperature during preheating with the first heating head (e.g., left heating head I, left heating head II, right heating head I, right heating head II), grain growth is fundamentally suppressed, resulting in an ultrafine grain structure and significantly improving the material's strength and toughness. When the first heating heads are sequentially withdrawn, the workpiece area covered by the remaining heating heads faces the risk of a sudden increase in heat input per unit area, easily leading to overheating and austenite grain coarsening. This invention, through precise "two-stage speed reduction and power reduction" programmed control, ensures that the heat received per unit time and per unit area in the final area of ​​the workpiece remains stable even with reduced heating sources, avoiding microstructure and grain coarsening caused by heat source withdrawal. The first speed reduction at the end (when left heating head I and left heating head II withdraw) is not simply a deceleration, but rather creates a smooth transition platform for subsequent, more precise power adjustments while maintaining production efficiency. It avoids sacrificing the overall quenching speed to preserve the final microstructure and also prevents quality fluctuations that may result from rapid power reduction. The left heating head III and the right heating head III use L-shaped silicon steel sheets instead of U-shaped silicon steel sheets for flow driving, so that the heat effect of the heating head is dispersed into the closing gap when the heating head closes at the end, avoiding the problem of non-martensitic structure due to insufficient heat in the heating gap after the heating head stops heating.

[0017] (4) The wind turbine main shaft bearing race material with the composition designed in this invention, combined with the wind turbine main shaft bearing race obtained by the hot working method of this invention, has high surface hardness (HRC 58-63), deep hardened layer depth, fine microstructure (4-5 grade) and grain size (8-10.5 grade) throughout the raceway. This solves the problem that the bearing raceway surface has soft bands and soft areas, and the microstructure and grain size are not up to standard after quenching by traditional surface hardening technology. Attached Figure Description

[0018] Figure 1This is a three-dimensional structural schematic diagram of the hollow guide punch of the present invention.

[0019] Figure 2 This is a schematic cross-sectional view of the hollow guide punch of the present invention.

[0020] Figure 3 This is a schematic diagram showing the arrangement of the left and right sets of heaters and the left and right sets of water spray boxes used in the quenching process of the bearing raceway surface.

[0021] Figure 4 This is a schematic diagram of the cross-section of the heating head and the structure of the U-shaped silicon steel sheet.

[0022] Figure 5 This is a schematic diagram of the cross-section of the heating head and the structure of the L-shaped silicon steel sheet.

[0023] Figure 6 This is a schematic diagram showing the initial configuration of four heating heads and two water spray boxes on the left and four heating heads and two water spray boxes on the right surrounding the outer raceway of the inner bearing ring.

[0024] Figure 7 This is a schematic diagram showing the symmetrical arrangement of four heating heads and two water spray boxes on the left and four heating heads and two water spray boxes on the right around the outer raceway of the inner ring of the bearing during the second stage of quenching.

[0025] Figure 8 This is a microstructure diagram of the outer raceway of the inner ring of the wind turbine main shaft bearing produced in Example 1.

[0026] Figure 9 This is a grain size diagram of the outer raceway of the inner ring of the wind turbine main shaft bearing produced in Example 1.

[0027] In the diagram, 1-inner bevel of the cone angle, 2-outer bevel of the cutting edge, 3-left heating head I, 4-left heating head II, 5-left heating head III, 6-left heating head IV, 7-left main water spray box, 8-left auxiliary water spray box, 9-right heating head I, 10-right heating head II, 11-right heating head III, 12-right heating head IV, 13-right main water spray box, 14-right auxiliary water spray box, 15-heating tube, 16-U-shaped silicon steel sheet, 17-heating surface, 18-bearing inner ring, 19-L-shaped silicon steel sheet. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] A wind turbine main shaft bearing ring, by weight percentage, comprises the following material composition: C: 0.43-0.55%, Si: 0.15-0.45%, Mn: 0.50-0.90%, Cr: 0.90-1.30%, Mo: 0.15-0.40%, Ni: 0.35-0.65%, V: 0.03-0.09%, Al: 0.010-0.050%, O≤15ppm, Ca≤12ppm, Ti≤25ppm, H≤2ppm, with the balance being Fe and unavoidable impurities.

[0030] The aforementioned wind turbine main shaft bearing rings are manufactured according to the following method: S1. Material Smelting: The chemical composition of the wind turbine main shaft bearing ring material by weight percentage includes: C: 0.43-0.55%, Si: 0.15-0.45%, Mn: 0.50-0.90%, Cr: 0.90-1.30%, Mo: 0.15-0.40%, Ni: 0.35-0.65%, V: 0.03-0.09%, Al: 0.010-0.050%, O≤15ppm, Ca≤12ppm, Ti≤25ppm, H≤2ppm, with the balance being Fe and unavoidable impurities.

[0031] According to the designed composition ratio, the raw materials are processed through electric furnace / converter primary refining, LF refining, VD / RH vacuum degassing, continuous casting, and slow cooling annealing to produce continuously cast billets of the required specifications; the specific operation is as follows: S1.1 Primary refining process: Primary refining is carried out using an electric furnace or converter. The proportioned raw materials are added to the electric furnace or converter and smelted by oxygen blowing. The carbon content of the tapped steel is controlled (generally controlled to be ≥0.08%) and the tapping temperature is controlled (generally controlled to be ≥1600℃). During the tapping process, slag-forming materials and some alloys are added with the steel stream for preliminary deoxidation and alloying to obtain primary molten steel. S1.2, LF Refining Process: The molten steel from the primary refining process is hoisted to the ladle refining furnace (LF furnace) station. After the ladle is in place, argon gas is turned on for stirring, and slag-forming materials required for the refining process are added to create reducing slag. Electrode heating is used. During the refining process, the composition of the molten steel is fine-tuned according to the test results to achieve the target value. After refining, the argon gas flow rate is adjusted for soft argon blowing treatment to remove inclusions by allowing them to float to the surface. S1.3, VD / RH vacuum degassing process: The molten steel after LF refining is hoisted to the VD furnace or RH furnace for vacuum degassing treatment. The vacuum degree and holding time are controlled. After vacuum treatment, the soft blowing argon process is continued to promote the further floating of inclusions. S1.4 Continuous Casting Process: Qualified molten steel after vacuum degassing is hoisted to the rotary table of the continuous casting machine and poured into the crystallizer via the tundish for fully protected casting to prevent secondary oxidation of the molten steel. The superheat of the molten steel in the tundish is controlled within the qualified range. Electromagnetic stirring, water cooling control and other technologies are used to optimize the internal quality of the billet and cast it into a continuous casting billet of the required specifications. S1.5 Slow Cooling and Annealing Process: Immediately after cutting, the continuously cast billet is either placed in a slow cooling pit or a holding furnace for slow cooling or annealing. The temperature upon entering the pit or furnace is controlled to be ≥600℃, and the slow cooling time is ≥72 hours. After slow cooling or annealing, the continuously cast billet is removed from the pit or furnace and air-cooled to room temperature. Slow cooling or annealing removes hydrogen from the steel, eliminates white spot defects, and softens the microstructure, facilitating subsequent processing.

[0032] The above steps are all mature existing technologies and will not be described in detail.

[0033] S2. Forging: The continuously cast billet obtained in step S1 is forged. Forging includes billet preparation, punching, and rolling processes. After forging, a ring forging is obtained. The specific operations are as follows: S2.1 Billet preparation process: The continuous casting billet obtained in step S1 is placed in a heating furnace and heated to 800℃ at a rate of ≤100℃ / h, held for 2h, and then heated to 1150-1200℃ at a rate of ≤120℃ / h, held for 3-5h; the heated billet is then subjected to three upsetting and two drawing processes, with a forging ratio ≥8; S2.2 Punching Process: A hollow guide punch with a tapered inner hole and a cutting edge is used for one-time punching. The structure of the hollow guide punch is as follows: Figure 1 and Figure 2 As shown, the end with the larger diameter of the inner hole of the cone angle is defined as the tail of the punch. The wall thickness d of the hollow guide punch is 0.2-0.3 times the outer diameter D of the tail of the punch. The angle (cone angle) between the inclined surface 1 of the inner hole of the cone angle and the vertical direction is 2-5°. The outer side of the cutting edge is provided with a punching angle of 4-8°, that is, the angle (punching angle) between the inclined surface 2 of the outer side of the cutting edge and the vertical direction is 4-8°. S2.3 Rolling Process: The punched material is returned to the furnace and reheated to 1150-1180℃ at a rate of ≤120℃ / h. Initial rolling and final rolling are performed on a ring rolling mill, with the time adjusted according to the workpiece dimensions. After final rolling, the material is placed in a box-type slow cooling device to cool to 300℃ before the temperature drops to 800℃, then removed from the box and air-cooled to room temperature to obtain the ring forging.

[0034] S3. Tempering Process: The ring forgings obtained in step S2 are subjected to tempering treatment, which includes quenching and tempering. The specific process is as follows: S3.1 Quenching process: Heat the workpiece (ring forging) rolled in step S2.3 to 830-880℃, and hold it at 1.2-1.5 min / mm according to the maximum wall thickness of the workpiece. After the holding is completed, take out the workpiece and immerse it in water for cooling within ≤2 min. After cooling to 100-120℃, remove it from the water and air cool it to room temperature. S3.2 Tempering process: Heat the quenched ring forging to 610-650℃, and hold it at 2.5-3.0 min / mm according to the maximum wall thickness of the workpiece. After the holding is completed, remove it from the furnace and air cool it to room temperature.

[0035] S4. Finish turning: Perform finish turning on the workpiece after heat treatment to the dimensions required for surface hardening.

[0036] S5. Raceway surface hardening: The precision-machined wind turbine main shaft bearing rings are surface hardened using a continuous scanning medium-frequency induction hardening method at a frequency of 2-3.5 kHz. The hardening structure includes two sets of heaters on the left and right sides, and two sets of water spray boxes on the left and right sides, such as... Figure 3 As shown, the left heater includes left heating heads I3, II4, III5, and IV6 arranged in sequence. The two left-side spray boxes include a left main spray box 7 and a left auxiliary spray box 8, with the left main spray box 7 located between the left heating head IV6 and the left auxiliary spray box 8. The right heater includes right heating heads I9, II10, III11, and IV12 arranged in sequence. The two right-side spray boxes include a right main spray box 13 and a right auxiliary spray box 14, with the right main spray box 13 located between the right heating head IV12 and the right auxiliary spray box 14. The spray hole density of the left main spray box 7 and the right main spray box 13 is equal, and the spray hole density of the left auxiliary spray box 8 and the right auxiliary spray box 14 is equal, with the spray hole density of the left main spray box 7 being greater than that of the left auxiliary spray box 8.

[0037] Furthermore, the left heating head I3, left heating head II4, left heating head IV6, right heating head I9, right heating head II10, and right heating head IV12 all include a heating tube 15 with a square cross-section and a U-shaped silicon steel sheet 16. The heating tube 15 is preferably a heating copper tube. One side of the heating copper tube is the heating surface 17, and the U-shaped silicon steel sheet 16 is disposed on the other three sides of the heating copper tube, such as... Figure 4 As shown. Both the left heating head III5 and the right heating head III11 include a heating copper tube with a square cross-section and an L-shaped silicon steel sheet 19. One side of the heating copper tube is the heating surface 17, and the L-shaped silicon steel sheet 19 is disposed on the other two adjacent sides of the heating copper tube, as shown. Figure 5 As shown. The side adjacent to the left heating head III5 and left heating head II4 does not have a silicon steel sheet, and the side adjacent to the right heating head III11 and right heating head II10 also does not have a silicon steel sheet, as shown. Figure 3 , Figure 6 , Figure 7 As shown.

[0038] Preferably, the widths of left heating head I3, left heating head II4, left heating head III5, right heating head I9, right heating head II10, and right heating head III11 are all 20-26mm, and the widths of left heating head IV6 and right heating head IV12 are all 15-19mm. This width refers to the sum of the width of the heating copper tube and the width of the silicon steel sheet.

[0039] In the initial state, the eight heating heads and two main water spray boxes on the left and right sides are symmetrically arranged around the raceway of the bearing ring to be heated. The left heating head I3, left heating head II4, left heating head III5, left heating head IV6, and left main water spray box 7 are respectively positioned and symmetrically arranged with the right heating head I9, right heating head II10, right heating head III11, right heating head IV12, and right main water spray box 13. The left auxiliary water spray box 8 and the right auxiliary water spray box 14 are stacked and staggered behind the left main water spray box 7 and the right main water spray box 13. Figure 6 As shown. The four heating heads on the left and the four heating heads on the right have the same structure and size. The main water spray box 7 on the left and the main water spray box 13 on the right have the same structure and size. The auxiliary water spray box 8 on the left and the auxiliary water spray box 14 on the right have the same structure and size.

[0040] Preferably, the distances between left heating head I3 and left heating head II4, left heating head III5 and left heating head IV6, right heating head I9 and right heating head II10, and right heating head III11 and right heating head IV12 are all 5-10mm; the distances between left heating head II4 and left heating head III5, and right heating head II10 and right heating head III11 are all 25-45mm; the distances between the left main water spray box 7 and left heating head IV6, and between the right main water spray box 13 and right heating head IV12, are all 15-35mm. Initially, the distance between the left main water spray box 7 and the right main water spray box 13 is ≤35mm, and the left auxiliary water spray box 8 and the right auxiliary water spray box 14 are stacked and staggered behind the left main water spray box 7 and the right main water spray box 13. During water spraying, the water sprayed from the left main water spray box 7 and the left auxiliary water spray box 8 is continuous on the bearing ring raceway surface, without any interruption in spraying. Similarly, the water sprayed from the right main water spray box 13 and the right auxiliary water spray box 14 is connected on the bearing raceway surface, with no interruption in spraying.

[0041] Taking the inner bearing ring 18 as an example, the process of quenching the precision-machined wind turbine main shaft bearing ring (hereinafter referred to as "bearing ring") using the above quenching structure includes: S5.1, First Stage: At the beginning of quenching, only the left heating head Ⅲ5, left heating head Ⅳ6, right heating head Ⅲ11, and right heating head Ⅳ12 are used to heat the bearing raceway. The left and right sets of heaters and the left and right sets of water spray boxes remain stationary. The bearing raceway rotates alternately left and right around the left heating head Ⅲ5, left heating head Ⅳ6, right heating head Ⅲ11, and right heating head Ⅳ12. The rotation distance on each side is 80-120mm, and the number of rotations is 3-6 times. After the temperature of the heated part of the bearing raceway reaches 870-890℃, the bearing raceway returns to the starting position and stops rotating. Then, the second stage begins.

[0042] S5.2, Second Stage: With the bearing ring stationary, the four heating heads and two water spray boxes on the left and the four heating heads and two water spray boxes on the right simultaneously rotate in opposite directions along the circumference of the bearing ring from their initial positions. The four heating heads on the left and four on the right simultaneously activate heating. At the same time, the left main water spray box 7 and the right main water spray box 13 begin spray cooling. When the left auxiliary water spray box 8 and the right auxiliary water spray box 14 move between the left main water spray box 7 and the right main water spray box 13, and the distance between the left auxiliary water spray box 8 and the right auxiliary water spray box 14 is 30-50mm, the left auxiliary water spray box 8 and the right auxiliary water spray box 14 begin spray cooling. Figure 7 As shown, the two water spray boxes on the left and two on the right cover the entire quenching surface and do not cause water backflow. The rotation speed of the eight heating heads on the left and right sides and the four water spray boxes on the left and right sides is 60-90 mm / min. During the quenching process, the gap between the heating head and the raceway remains consistent. The heating power of left heating heads I3 and II4 is always higher than that of left heating heads III5 and IV6, and the heating power of right heating heads I9 and II10 is always higher than that of right heating heads III11 and IV12. The heating power of left heating heads I3 and II4 is 1.1-1.2 times that of left heating heads III5 and IV6, and the heating power of right heating heads I9 and II10 is 1.1-1.2 times that of right heating heads III11 and IV12. When the left and right sets of heaters rotate to a distance of 2-5mm between left heating head I3 and right heating head I9, left heating heads I3 and II4 stop heating and exit the raceway position, and the raceway surface quenching enters the third stage.

[0043] S5.3, Third Stage: After the left heating head I3 and left heating head II4 stop heating and exit the raceway position, the left heating head III5, left heating head IV6, right heating head I9, right heating head II10, right heating head III11, and right heating head IV12 continue to rotate and heat in the direction of rotation of the second stage. At the same time, the two water spray boxes on the left and the two water spray boxes on the right continue to rotate and spray water in the direction of rotation of the second stage. The rotation speeds of the left heating head III5, left heating head IV6, right heating head I9, right heating head II10, right heating head III11, right heating head IV12, the two water spray boxes on the left, and the two water spray boxes on the right are all reduced to 35-50 mm / min and kept at the same rotation speed. The heating power of the left heating head III5, left heating head IV6, right heating head III11, and right heating head IV12 is reduced by 4-8% compared to the corresponding heating head in the second stage, while the heating power of the right heating head I9 and right heating head II10 is increased by 8-12% compared to the corresponding heating head in the second stage. This process continues until the distance between the right heating head I9 and the left heating head III5 is 4-6 mm. Then, the right heating head I9 and right heating head II10 stop heating and exit the raceway position. The raceway surface quenching then enters the fourth stage.

[0044] S5.4, Fourth Stage: After the right heating heads I9 and II10 stop heating and exit the raceway position, the left heating heads III5, IV6, III11, and IV12 continue to rotate and heat in the direction of rotation of the second stage. At the same time, the two water spray boxes on the left and the two water spray boxes on the right continue to rotate and spray water in the direction of rotation of the second stage. The rotation speed of the remaining four heating heads and the two water spray boxes on the left and the two water spray boxes on the right are reduced to 20-30 mm / min and kept at the same rotation speed. The heating power of the left heating heads III5, IV6, III11, and IV12 is reduced by 3-5% compared with the corresponding heating heads in the third stage, until the distance between the left heating head III5 and the right heating head III11 is 1-3 mm and heating stops. All heating heads exit the raceway position within 2 seconds, and the tail water spray box is turned on for direct spray cooling. The position where the distance between the left heating head Ⅲ5 and the right heating head Ⅲ11 is 1-3mm is defined as the end heating area. The position of the tail spray water box corresponds to the position of this end heating area. The spray surface of the tail spray water box is large enough to cover all uncooled parts of the end heating area.

[0045] S5.5 After cooling is completed (300-400 seconds after the tail spray water box sprays water), the workpiece is tempered within 8 hours. The tempering temperature is 170±10℃ and the holding time is 4-6 hours. After the holding time is completed, the workpiece is taken out of the furnace and air-cooled to room temperature to obtain the wind turbine main shaft bearing ring.

[0046] The present invention will now be described in detail with reference to specific embodiments: Example 1

[0047] S1. Material Smelting: The chemical composition of the wind turbine main shaft bearing ring material, by weight percentage, includes: C: 0.47%, Si: 0.32%, Mn: 0.70%, Cr: 1.12%, Mo: 0.26%, Ni: 0.55%, V: 0.06%, Al: 0.026%, O: 9ppm, Ca: 7ppm, Ti: 15ppm, H: 0.8ppm, with the balance being Fe and unavoidable impurities. According to the designed composition ratio, the raw materials are smelted into φ500mm continuous casting billets through electric furnace / converter primary smelting, LF refining, VD / RH vacuum degassing, continuous casting, and slow cooling annealing.

[0048] S2. Forging: The continuously cast billet obtained in step S1 is placed in a heating furnace and heated to 800℃ at a rate of 100℃ / h, held for 2 hours, and then heated to 1200℃ at a rate of 120℃ / h, held for 5 hours; the heated billet is then subjected to three upsetting and two drawing processes to complete the billet preparation, with a forging ratio ≥8; a hollow guide punch with a tapered inner hole, a cutting edge, and a tail outer diameter of 280mm is used for punching. The structure of the hollow guide punch is as follows: Figure 1 and Figure 2 As shown, the punched material is returned to the furnace and reheated to 1180°C at a rate of 120°C / h. It is then subjected to initial rolling and final rolling on a ring rolling mill. After the final rolling is completed, the material temperature is cooled to 300°C in a box-type slow cooling device before it drops to 800°C. After that, it is removed from the box and air-cooled to room temperature to obtain the ring forging.

[0049] S3. Tempering process: Quenching the ring forging obtained in step S2: Heat the ring forging to 880℃, hold for 3 hours, remove it, cool it in water, cool it to 120℃, and then air cool it to room temperature; heat the quenched ring forging to 650℃, hold for 6 hours, and then air cool it to room temperature.

[0050] S4. Precision turning: Perform precision turning on the workpiece after heat treatment to machine it into the inner ring 18 of the wind turbine main shaft bearing with a diameter of φ2027mm.

[0051] S5. Raceway Surface Quenching: Based on the outer raceway dimensions of the inner ring 18 of the wind turbine main shaft bearing obtained in step S4, a contour inductor (including a heating head and a water spray box) is fabricated for surface quenching, ensuring that the heating surface 17 of the heating head matches the shape of the outer raceway surface of the inner ring 18. The quenching structure includes two sets of heaters on the left and right sides, and two sets of water spray boxes on the left and right sides. The left heater includes left heating head I3, left heating head II4, left heating head III5, and left heating head IV6 arranged in sequence. The two water spray boxes on the left side include a left main water spray box 7 and a left auxiliary water spray box 8, with the left main water spray box 7 located between the left heating head IV6 and the left auxiliary water spray box 8. The right heater includes right heating head I9, right heating head II10, right heating head III11, and right heating head IV12 arranged in sequence. The two water spray boxes on the right side include a right main water spray box 13 and a right auxiliary water spray box 14, with the right main water spray box 13 located between the right heating head IV12 and the right auxiliary water spray box 14. The spray hole density of the left main water spray box 7 and the right main water spray box 13 is equal, and the spray hole density of the left auxiliary water spray box 8 and the right auxiliary water spray box 14 is equal, with the spray hole density of the left main water spray box 7 being greater than that of the left auxiliary water spray box 8. In the initial state, the eight heating heads and two main water spray boxes on the left and right sides are symmetrically arranged around the outer raceway of the inner bearing ring 18 to be heated. The left heating head I3, left heating head II4, left heating head III5, left heating head IV6, and left main water spray box 7 are respectively positioned and symmetrically arranged with the right heating head I9, right heating head II10, right heating head III11, right heating head IV12, and right main water spray box 13. The left auxiliary water spray box 8 and the right auxiliary water spray box 14 are stacked and staggered behind the left main water spray box 7 and the right main water spray box 13. The four heating heads on the left and the four heating heads on the right have the same structure and size. The main water spray box 7 on the left and the main water spray box 13 on the right have the same structure and size. The auxiliary water spray box 8 on the left and the auxiliary water spray box 14 on the right have the same structure and size.

[0052] The widths of left heating heads I3, II4, III5, I9, II10, and III11 are all 20mm, while the widths of left heating heads IV6 and IV12 are all 15mm. The distances between left heating head I3 and left heating head II4, left heating head III5 and left heating head IV6, right heating head I9 and right heating head II10, right heating head III11 and right heating head IV12 are all 5mm, and the distances between left heating head II4 and left heating head III5, right heating head II10 and right heating head III11 are all 25mm; the distances between left main water spray box 7 and left heating head IV6, and between right main water spray box 13 and right heating head IV12 are all 15mm. In the initial state, the distance between left main water spray box 7 and right main water spray box 13 is 30mm. Left auxiliary water spray box 8 and right auxiliary water spray box 14 are stacked and staggered behind left main water spray box 7 and right main water spray box 13.

[0053] The quenching process includes: S5.1, First Stage: At the beginning of quenching, only the left heating head Ⅲ5, left heating head Ⅳ6, right heating head Ⅲ11, and right heating head Ⅳ12 are used to heat the outer raceway of the inner bearing ring 18. The two sets of heaters on the left and right sides and the two sets of water spray boxes on the left and right sides remain stationary. The inner bearing ring 18 rotates alternately left and right around the left heating head Ⅲ5, left heating head Ⅳ6, right heating head Ⅲ11, and right heating head Ⅳ12. The rotation distance on each side is 80mm, and the number of rotations is 3. After the rotation heating reaches the temperature of the heated position of the bearing ring raceway at 870℃, the inner bearing ring 18 returns to the starting position and stops rotating, and then enters the second stage.

[0054] S5.2, Second Stage: The inner ring 18 of the bearing remains stationary. The four heating heads and two water spray boxes on the left and right sides simultaneously start rotating in opposite directions along the circumference of the inner ring 18 from their initial positions. The four heating heads on the left and four on the right simultaneously start heating. At the same time, the main water spray box 7 on the left and the main water spray box 13 on the right start spray cooling. When the auxiliary water spray box 8 on the left and the auxiliary water spray box 14 on the right move between the main water spray box 7 on the left and the main water spray box 13 on the right, and the distance between the auxiliary water spray box 8 on the left and the auxiliary water spray box 14 on the right is 35mm, the auxiliary water spray box 8 on the left and the auxiliary water spray box 14 on the right start spray cooling. The spray cooling area of ​​the two water spray boxes on the left and the two water spray boxes on the right covers the entire quenching surface without backflow. The rotation speed of the eight heating heads and the four water spray boxes on the left and right sides is 90mm / min. The gap between the heating head and the raceway remains consistent throughout the quenching process. Left heating heads I3 and II4 have a heating power of 43KW, left heating heads III5 and IV6 have a heating power of 39KW, right heating heads I9 and II10 have a heating power of 42KW, and right heating heads III11 and IV12 have a heating power of 37.3KW. When the left and right sets of heaters rotate to a distance of 3mm between left heating head I3 and right heating head I9, left heating heads I3 and II4 stop heating and exit the raceway position, and the raceway surface quenching enters the third stage.

[0055] S5.3, Third Stage: After the left heating heads I3 and II4 stop heating and exit the raceway position, the left heating heads III5, IV6, I9, II10, III11, and IV12 continue to rotate and heat in the direction of rotation of the second stage. At the same time, the two water spray boxes on the left and the two water spray boxes on the right continue to rotate and spray water in the direction of rotation of the second stage. The rotation speed of the left heating heads III5, IV6, I9, II10, III11, and IV12, the two water spray boxes on the left and the two water spray boxes on the right all decrease to 50 mm / min and maintain the same rotation speed among themselves. The heating power of the left heating heads III5 and IV6 decreases to 37.4KW, the heating power of the right heating heads I9 and II10 increases to 46KW, and the heating power of the right heating heads III11 and IV12 decreases to 35.8KW. Continue quenching continuously. When the distance between the right heating head I9 and the left heating head III5 is 4mm, the right heating head I9 and the right heating head II10 stop heating and exit the raceway position. The raceway surface quenching enters the fourth stage.

[0056] S5.4, Fourth Stage: After the right heating heads I9 and II10 stop heating and exit the raceway position, the left heating heads III5, IV6, III11, and IV12 continue to rotate and heat in the direction of rotation of the second stage at a speed of 30 mm / min (maintaining the same rotation speed among them). At the same time, the two water spray boxes on the left and the two on the right continue to rotate and spray water in the direction of rotation of the second stage at a speed of 30 mm / min (maintaining the same rotation speed among them). The heating power of the left heating heads III5 and IV6 decreases to 36KW, and the heating power of the right heating heads III11 and IV12 decreases to 34.5KW. Heating stops when the distance between the left heating heads III5 and III11 is 1mm. All heating heads exit the raceway position within 2 seconds, and the tail water spray box is opened for direct spray cooling. The spray surface of the tail water spray box is large enough to cover all uncooled parts of the final heated area.

[0057] S5.5 After cooling is completed (300 seconds after the tail spray water box sprays water), the workpiece is tempered within 8 hours. The tempering temperature is 170±10℃ and the holding time is 4 hours. After the holding time is completed, the workpiece is taken out of the furnace and air-cooled to room temperature.

[0058] The performance test results of the outer raceway of the inner ring 18 of the wind turbine main shaft bearing obtained by the raceway surface hardening treatment in this embodiment are shown in Table 1: Table 1. Test results of various performance parameters of the outer raceway of the inner ring of the wind turbine main shaft bearing.

[0059] As shown in Table 1, the bearing rings processed by the hot working method of the wind turbine main shaft bearing rings of the present invention have high surface hardness, deep hardened layer depth, and fine microstructure and grain size throughout the raceway.

[0060] Figure 8 The image shows the microstructure of the outer raceway of the inner ring 18 of the wind turbine main shaft bearing produced in Example 1 (photographed with a microscope). It can be seen that its microstructure is grade 5.

[0061] Figure 9 The image shows the grain size of the outer raceway of the inner ring 18 of the wind turbine main shaft bearing manufactured in Example 1 (photographed with a microscope). It can be seen that the grain size is grade 9.

[0062] It should be noted that the above embodiments are only illustrative examples of the inner race 18 of the wind turbine main shaft bearing and are not intended to limit the present invention. The outer race of the wind turbine main shaft bearing can also be manufactured in accordance with the above method. The difference is that when the raceway surface is quenched, the heating head and the water spray box are symmetrically arranged in the outer raceway in the same way, corresponding to the inner raceway of the outer raceway. This will not be described in detail again.

[0063] The above description is merely an embodiment of the present invention and is not intended to limit the present invention in any way. The present invention can also have other embodiments based on the above structure and function, which will not be listed hereafter. Therefore, any simple modifications, equivalent changes, and alterations made by those skilled in the art to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for hot-working bearing rings of a wind turbine main shaft, characterized in that, Includes the following steps: S1. Material smelting: According to the designed composition ratio, the raw materials are taken and smelted into continuous casting billets of the required specifications through electric furnace / converter primary smelting, LF refining, VD / RH vacuum degassing, continuous casting, and slow cooling annealing. S2. The continuously cast billet obtained in step S1 is forged. The forging process includes billet preparation, punching, and rolling. After forging, a ring forging is obtained. S3. The ring forging obtained in step S2 is subjected to quenching and tempering treatment, which includes quenching and tempering. S4. Perform precision machining on the tempered bearing rings; S5. The bearing rings obtained in step S4 are subjected to raceway surface quenching. The quenching structure includes two sets of heaters on the left and right sides and two sets of water spray boxes on the left and right sides. The left heater includes left heating head I (3), left heating head II (4), left heating head III (5), and left heating head IV (6) arranged in sequence. The two water spray boxes on the left side include a left main water spray box (7) and a left auxiliary water spray box (8). The left main water spray box (7) is located between the left heating head IV (6) and the left auxiliary water spray box (8). The right heater includes right heating head I (9), right heating head II (10), right heating head III (11), and right heating head IV (12) arranged in sequence. The two water spray boxes on the right side include a right main water spray box (13) and a right auxiliary water spray box (14). 14), the right main water spray box (13) is located between the right heating head IV (12) and the right auxiliary water spray box (14); in the initial state, the eight heating heads and two main water spray boxes on the left and right sides are symmetrically arranged around the raceway of the bearing ring to be heated. The left heating head I (3), left heating head II (4), left heating head III (5), left heating head IV (6), and left main water spray box (7) correspond to the right heating head I (9), right heating head II (10), right heating head III (11), right heating head IV (12), and right main water spray box (13) respectively and are symmetrically arranged. The left auxiliary water spray box (8) and the right auxiliary water spray box (14) are superimposed and staggered and arranged behind the left main water spray box (7) and the right main water spray box (13); The steps for surface hardening of bearing raceway using the above hardening structure include: S5.1, First stage: At the beginning of quenching, only the left heating head III (5), left heating head IV (6), right heating head III (11), and right heating head IV (12) are used to heat the bearing raceway. The left and right sets of heaters and the left and right sets of water spray boxes remain stationary. The bearing raceway rotates alternately left and right around the left heating head III (5), left heating head IV (6), right heating head III (11), and right heating head IV (12). The rotation distance on one side is 80-120mm. After the rotation heating reaches the temperature of the heated position of the bearing raceway at 870-890℃, the bearing raceway returns to the starting position and stops rotating. Then, the second stage begins. S5.2, Second Stage: The bearing ring remains stationary. The four heating heads on the left and the two water spray boxes on the left and the four heating heads on the right and the two water spray boxes on the right simultaneously start rotating in opposite directions along the circumference of the bearing ring from their initial positions. The four heating heads on the left and the four heating heads on the right start heating simultaneously. At the same time, the left main water spray box (7) and the right main water spray box (13) start spraying for cooling. When the left auxiliary water spray box (8) and the right auxiliary water spray box (14) move to the space between the left main water spray box (7) and the right main water spray box (13) and the distance between the left auxiliary water spray box (8) and the right auxiliary water spray box (14) is 30-50mm, the left auxiliary water spray box (8) and the right auxiliary water spray box (14) start spraying for cooling. The spray cooling area of ​​the spray box and the two spray boxes on the right side covers the entire quenching surface and does not backflow. The rotation speed of the eight heating heads on the left and right sides and the four spray boxes on the left and right sides is 60-90mm / min. The heating power of the left heating head I (3) and the left heating head II (4) is always higher than that of the left heating head III (5) and the left heating head IV (6). The heating power of the right heating head I (9) and the right heating head II (10) is always higher than that of the right heating head III (11) and the right heating head IV (12). When the left and right heaters rotate to the distance between the left heating head I (3) and the right heating head I (9) is 2-5mm, the left heating head I (3) and the left heating head II (4) stop heating and exit the raceway position. The raceway surface quenching enters the third stage. S5.3, Third Stage: After the left heating head I (3) and left heating head II (4) stop heating and exit the raceway position, the left heating head III (5), left heating head IV (6), right heating head I (9), right heating head II (10), right heating head III (11), and right heating head IV (12) continue to rotate and heat in the direction of rotation of the second stage. At the same time, the two water spray boxes on the left and the two water spray boxes on the right continue to rotate and spray water in the direction of rotation of the second stage. The rotation speed of the left heating head III (5), left heating head IV (6), right heating head I (9), right heating head II (10), right heating head III (11), right heating head IV (12), the two water spray boxes on the left, and the two water spray boxes on the right all decrease to 35-50. The heating power of the left heating head III (5), left heating head IV (6), right heating head III (11), and right heating head IV (12) is reduced by 4-8% compared to the corresponding heating head in the second stage, while the heating power of the right heating head I (9) and right heating head II (10) is increased by 8-12% compared to the corresponding heating head in the second stage. The quenching continues in this manner. When the distance between the right heating head I (9) and the left heating head III (5) is 4-6 mm, the right heating head I (9) and right heating head II (10) stop heating and exit the raceway position. The raceway surface quenching enters the fourth stage. S5.4, Fourth Stage: After the right heating head I (9) and right heating head II (10) stop heating and exit the raceway position, the left heating head III (5), left heating head IV (6), right heating head III (11), and right heating head IV (12) continue to rotate and heat in the direction of rotation of the second stage. At the same time, the two water spray boxes on the left and the two water spray boxes on the right continue to rotate and spray water in the direction of rotation of the second stage. The rotation speed of the remaining four heating heads and the two water spray boxes on the left and the two water spray boxes on the right is reduced to 20-30 mm / s. min and keep the rotation speeds of each other the same. The heating power of the left heating head III (5), left heating head IV (6), right heating head III (11), and right heating head IV (12) is reduced by 3-5% compared with the heating power of the corresponding heating head in the third stage. Heating stops when the distance between the left heating head III (5) and the right heating head III (11) is 1-3mm. All heating heads are removed from the raceway position within 2s. At the same time, the tail spray water box is turned on for direct spray cooling. The spray surface of the tail spray water box is large enough to cover all uncooled parts of the end heating area. S5.5 After cooling, the workpiece is tempered within 8 hours at a temperature of 170±10℃ and a holding time of 4-6 hours. After holding, the workpiece is removed from the furnace and air-cooled to room temperature to obtain the wind turbine main shaft bearing ring.

2. The hot working method for wind turbine main shaft bearing rings as described in claim 1, characterized in that, In step S1, the chemical composition of the wind turbine main shaft bearing ring material, by weight percentage, includes: C: 0.43-0.55%, Si: 0.15-0.45%, Mn: 0.50-0.90%, Cr: 0.90-1.30%, Mo: 0.15-0.40%, Ni: 0.35-0.65%, V: 0.03-0.09%, Al: 0.010-0.050%, O≤15ppm, Ca≤12ppm, Ti≤25ppm, H≤2ppm, with the balance being Fe and unavoidable impurities.

3. The hot working method for wind turbine main shaft bearing rings as described in claim 1, characterized in that, The forging process specifically includes: placing the continuously cast billet obtained in step S1 in a heating furnace and heating it to 800℃ at a rate of ≤100℃ / h, holding it at that temperature for 2 hours, then heating it to 1150-1200℃ at a rate of ≤120℃ / h, holding it at that temperature for 3-5 hours, and then performing three upsettings and two drawings on the heated billet; then punching the billet, returning the punched material to the furnace, and reheating it to 1150-1180℃ at a rate of ≤120℃ / h, performing initial rolling and final rolling on a ring rolling mill, and after the final rolling is completed, cooling the material to 300℃ in a box-type slow cooling device before the temperature drops to 800℃, and then air cooling it to room temperature to obtain the ring forging.

4. The hot working method for wind turbine main shaft bearing rings as described in claim 3, characterized in that, The punching process uses a hollow guide punch with a conical inner hole and a cutting edge to punch holes in one step. The end with the larger diameter of the conical inner hole of the hollow guide punch is defined as the tail of the punch. The wall thickness d of the hollow guide punch is 0.2-0.3 times the outer diameter D of the tail of the punch. The angle between the inclined surface (1) of the conical inner hole and the vertical direction is 2-5°, and the angle between the inclined surface (2) of the outer edge and the vertical direction is 4-8°.

5. The hot working method for wind turbine main shaft bearing rings as described in claim 1, characterized in that, The heat treatment specifically includes: heating the forged ring forging to 830-880℃, holding it at 1.2-1.5 min / mm according to the maximum wall thickness of the ring forging, removing the ring forging after holding, immersing it in water for cooling within ≤2 min, cooling it to 100-120℃, removing it from the water and air cooling it to room temperature, then heating the ring forging to 610-650℃, holding it at 2.5-3.0 min / mm according to the maximum wall thickness of the ring forging, removing it from the furnace and air cooling it to room temperature.

6. The hot working method for wind turbine main shaft bearing rings as described in claim 1, characterized in that, The widths of left heating head I (3), left heating head II (4), left heating head III (5), right heating head I (9), right heating head II (10), and right heating head III (11) are all 20-26mm, and the widths of left heating head IV (6) and right heating head IV (12) are all 15-19mm.

7. The hot working method for wind turbine main shaft bearing rings as described in claim 1 or 5, characterized in that, The distance between left heating head I (3) and left heating head II (4), left heating head III (5) and left heating head IV (6), right heating head I (9) and right heating head II (10), right heating head III (11) and right heating head IV (12) is 5-10mm. The distance between left heating head II (4) and left heating head III (5), right heating head II (10) and right heating head III (11) is 25-45mm. The distance between left main water spray box (7) and left heating head IV (6), right main water spray box (13) and right heating head IV (12) is 15-35mm. In the initial state, the distance between left main water spray box (7) and right main water spray box (13) is ≤35mm. Left auxiliary water spray box (8) and right auxiliary water spray box (14) are stacked and staggered behind the left main water spray box (7) and right main water spray box (13).

8. The hot working method for wind turbine main shaft bearing rings as described in claim 1, characterized in that, The heating power of the left heating head I (3) and the left heating head II (4) is 1.1-1.2 times that of the left heating head III (5) and the left heating head IV (6). The heating power of the right heating head I (9) and the right heating head II (10) is 1.1-1.2 times that of the right heating head III (11) and the right heating head IV (12).

9. The hot working method for wind turbine main shaft bearing rings as described in claim 1, characterized in that, The surface hardness (HRC) of the raceway of the wind turbine main shaft bearing ring is 58-63.

10. The wind turbine main shaft bearing race obtained by the method described in claim 1.

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