Intermediate-frequency heating integral surface quenching method for TRB main shaft bearing of wind driven generator

Abstract

The invention provides a medium-frequency heating integral surface quenching method for a TRB main shaft bearing of a wind driven generator, which comprises the following steps: placing a workpiece made of medium-carbon alloy steel on induction heating equipment, and enabling a plurality of induction heaters to be close to a working raceway surface of the workpiece; the method comprises the following steps: heating a working raceway surface of a workpiece by using an induction heater in a high-speed rotating process of the workpiece, stopping heating by using the induction heater when the temperature of the working raceway surface of the workpiece reaches a threshold value, stopping rotating the workpiece, and then immersing the workpiece into a cooling liquid for overall surface quenching; the medium-carbon alloy steel medium-frequency heating surface quenching mode is adopted, a traditional hardenability steel overall quenching mode can be replaced, the working surface of the ferrule has high abrasion resistance and fatigue resistance, the toughness of the center position of the ferrule can be improved, and therefore the impact resistance of the center of the ferrule is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of heat treatment of a TRB main shaft bearing of a wind turbine generator, and in particular relates to a medium-frequency heating integral surface quenching method for a TRB main shaft bearing of a wind turbine generator. Background Art

[0002] Wind turbine TRB main shaft bearings (i.e. tapered roller bearings) are the core components of wind turbines. They are mainly responsible for absorbing the aerodynamic load of the impeller and transmitting power, and are known as the "heart" of wind turbines. They are used to support the rotation of wind turbines to generate electricity, especially in wind turbines with main shafts and gearboxes, where they play a key role as the main support.

[0003] At present, the existing TRB spindle bearing rings with a diameter of more than 1.5 meters are generally made of high-carbon chromium bearing steel or carburized steel. High-carbon chromium bearing steel (such as GCr15, GCr15SiMn, etc.) is heat treated by integral quenching for the rings; carburized steel (such as 20Cr2Ni4A, 20Cr2Mn2Mo, etc.) is first carburized and then integrally quenched during heat treatment. High-carbon chromium bearing steel has unique advantages in wear resistance and fatigue resistance and is widely used. However, for large impact loads, the working surface of the bearing is required to have sufficient strength, wear resistance and fatigue resistance, and the core position of the ring is also required to have strong impact resistance and toughness. At this time, high-carbon chromium bearing steel cannot meet the above requirements, and the carburizing and quenching of carburized steel is adopted.

[0004] However, the carburizing and quenching scheme of carburizing steel involves a carburizing process and subsequent quenching and tempering treatments in actual operation. The diffusion of carbon needs to be controlled during the carburizing process, as well as the subsequent quenching and tempering temperature and time to ensure that the required surface hardness and core toughness are obtained. The heat treatment process is relatively complicated and has the problem of long process time.

[0005] The bearing rings in the prior art use medium carbon alloy steel to solve the above-mentioned problems of high carbon chromium bearing steel and carburized steel, and have the advantage of a simple quenching process. However, after heat treatment, soft band areas are easily formed at the starting and ending positions of the rings, which limits the use of the rings.

[0006] In summary, there is an urgent need for a quenching method that can make the workpiece have high surface wear resistance, fatigue resistance, core impact resistance after quenching, no pollution to the environment, short production cycle, low cost, uniform heating during quenching, uniform heat treatment structure, uniform hardness, uniform hardened layer, no soft zone, small parts heat treatment deformation, high reliability, and is applied to the TRB main shaft bearing of wind turbines to solve the above problems. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a medium frequency heating overall surface quenching method for the TRB main shaft bearing of a wind turbine. Multiple induction heaters are used to heat the working surface of the workpiece during the high-speed rotation of the workpiece, so that the quenching surface of the workpiece can be medium-frequency heated under the same state, and then the overall quenching is performed. The surface of the ring can have high wear resistance and fatigue resistance, and the core of the workpiece has impact resistance. The quenching surface structure is uniform and the deformation is small. The processing is simple and the cost is low, thereby improving the overall comprehensive performance of the ring after quenching.

[0008] The technical solution adopted by the present invention is: a medium-frequency heating overall surface quenching method for a TRB main shaft bearing of a wind turbine, a workpiece made of medium-carbon alloy steel is placed on an induction heating device, and a plurality of induction heaters are placed close to the working raceway surface of the workpiece so that the working raceway surface of the workpiece is heated by the induction heater during high-speed rotation of the workpiece. When the temperature of the working raceway surface of the workpiece reaches a threshold value, the induction heater stops heating, the workpiece stops rotating, and then the workpiece is immersed in a coolant for overall surface quenching.

[0009] There are four induction heaters, which are evenly distributed around the central axis of the workpiece.

[0010] The workpiece is an inner ring or an outer ring of a TRB main shaft bearing of a wind turbine, and the workpiece is made of medium carbon alloy steel; the workpiece is horizontally placed on the induction heating device, and its central axis is perpendicular to the horizontal plane.

[0011] The working raceway surface of the workpiece includes a raceway surface in contact with the outer diameter of the rolling element.

[0012] The working raceway surface of the workpiece also includes a rib surface in contact with the end surface of the rolling element.

[0013] The working raceway surface of the workpiece is located at the inner wall or outer wall of the workpiece.

[0014] During the high-speed rotation of the workpiece, a thermometer is used to monitor the heating temperature of the working raceway surface in real time.

[0015] The diameter of the workpiece is greater than 1500 mm.

[0016] The induction heating equipment includes a cooling pool capable of accommodating coolant, wherein the interior of the cooling pool is provided with a workbench capable of being raised and lowered, and the surface of the workbench is provided with four movable seats, which are evenly distributed around the center of the workbench, and the movable seats can move toward the center of the workbench or away from the center of the workbench, and each movable seat is provided with a horizontally arranged and rotatable supporting roller and a vertically arranged and rotatable limiting roller, wherein the end of one of the supporting rollers is connected to a motor.

[0017] A stirring rod for stirring the coolant is also provided inside the cooling pool, and a liquid inlet and a liquid outlet are provided on the side wall of the cooling pool.

[0018] The beneficial effects of the present invention are: (1) The present invention adopts the medium-frequency heating surface quenching method of medium-carbon alloy steel, which can replace the overall quenching method of traditional hardenable steel, so that the working surface of the ring not only has strong wear resistance and fatigue resistance, but also can improve the toughness of the core of the ring, thereby improving the impact resistance of the core of the ring; (2) The present invention adopts the method of medium-frequency heating surface quenching of medium-carbon alloy steel, which can replace the traditional method of overall quenching after carburizing, can reduce the pollution problem in the heat treatment process, and has the advantages of short cycle, low cost and low processing difficulty; (3) The present invention adopts the method of high-speed rotation of the ferrule and static heating of the induction heater, which can solve the problem of quenching soft band on the workpiece during traditional medium-frequency quenching, and solve the problem that the ferrule cannot be operated at high speed and the soft band is prone to fatigue damage caused by the traditional quenching method with soft band; (4) The heat treatment method of the present invention using the highly rotating heating of the ferrule can make the workpiece heated evenly, and the heat treatment structure, hardness and hardened layer of each part of the workpiece are uniform, so that the workpiece has the advantages of small deformation, high reliability and good overall comprehensive performance after heat treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a diagram of the installation structure of the workpiece during heat treatment of the present invention; Figure 2 It is a partial structural diagram of the induction heating device of the present invention; Figure 3 It is a structural diagram of the outer ring of the bearing of the present invention; Figure 4 It is a structural diagram of the inner ring of the bearing of the present invention.

[0020] Markings in the figure: 1. Cooling pool; 2. Workbench; 3. Induction heater; 4. Thermometer; 5. Moving seat; 6. Support roller; 7. Limiting roller. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] As shown in the figure, a method for medium-frequency heating overall surface quenching of a TRB main shaft bearing of a wind turbine is provided. A workpiece made of medium-carbon alloy steel is placed on an induction heating device. By placing a plurality of induction heaters 3 close to the working raceway surface of the workpiece, the working raceway surface of the workpiece is heated by the induction heaters 3 during high-speed rotation of the workpiece. When the temperature of the working raceway surface of the workpiece reaches a threshold value, the induction heaters 3 stop heating, the workpiece stops rotating, and then the workpiece is immersed in a coolant for overall surface quenching.

[0023] Among them, the diameter of the workpiece is greater than 1500mm, and the induction heating equipment mainly includes a cooling pool 1 that can accommodate coolant. The interior of the cooling pool 1 is provided with a workbench 2 that can be raised and lowered. Four movable seats 5 are provided on the surface of the workbench 2. The four movable seats 5 are evenly distributed around the center of the workbench 2. The movable seats 5 can move toward the center of the workbench 2 or away from the center of the workbench 2 so as to be suitable for rings of different sizes. Each movable seat 5 is equipped with a horizontally arranged and rotatable support roller 6 and a vertically arranged and rotatable limiting roller 7. The support roller 6 is used to contact the lower end surface of the workpiece to support the workpiece. The limiting roller 7 is used to fit with the inner wall or outer wall of the workpiece, thereby limiting the horizontal movement of the workpiece without affecting the rotation of the workpiece, so that the workpiece has only the degree of freedom to rotate around its central axis under the action of its own gravity. Furthermore, in order to drive the rotation of the workpiece, a motor is connected to the end of one of the support rollers 6. Driven by the motor, the support roller 6 rotates, thereby driving the workpiece above to rotate.

[0024] In this example, there are four induction heaters 3, which are evenly distributed around the central axis of the workpiece, and each induction heater 3 can move in the front, back, up, down, left and right directions. The heating surface of the induction heater 3 can be consistent with the shape of the working surface of the workpiece, and the position of the induction heater 3 can be quickly adjusted through the PLC controller.

[0025] More specifically, a stirring rod for stirring the coolant is provided inside the cooling pool 1, and a liquid inlet and a liquid outlet are provided on the side wall of the cooling pool 1, so as to achieve the stirring and circulation effect of the coolant. When the local temperature of the coolant changes, the stirring rod works to keep the overall temperature of the coolant consistent. When the coolant temperature is too high or the coolant is highly contaminated, the coolant is circulated from the liquid inlet and the liquid outlet.

[0026] The lifting function of the above-mentioned workbench 2, the installation structure and working principle of the induction heater 3, the stirring rod structure and principle inside the cooling pool 1, and the coolant circulation structure and principle are all conventional technologies in the prior art and will not be elaborated on here.

[0027] The workpiece is an inner ring or an outer ring of a TRB main shaft bearing of a wind turbine, and the workpiece is made of medium carbon alloy steel; the workpiece is horizontally placed on the induction heating device, and its central axis is perpendicular to the horizontal plane.

[0028] The working raceway surface of the workpiece includes a raceway surface in contact with the outer diameter of the rolling element. More specifically, the working raceway surface of the workpiece also includes a rib surface in contact with the end surface of the rolling element.

[0029] The working raceway surface of the workpiece is located at the inner wall or outer wall of the workpiece.

[0030] During the high-speed rotation of the workpiece, the heating temperature of the working raceway surface is monitored in real time by using the thermometer 4 , wherein the thermometer 4 may be an infrared thermometer.

[0031] The medium frequency heating overall surface quenching method for the TRB main shaft bearing of a wind turbine in this embodiment specifically includes the following steps: Step 1: Figure 1 As shown, the workpiece is placed flat on the induction heating device. The workpiece can be the outer ring of the TRB main shaft bearing of the wind turbine generator (such as Figure 3 as shown) or inner ferrule (as shown Figure 4 As shown in the figure), adjust the position of the workpiece so that the workpiece can perform horizontal rotational motion around its own central axis under the driving action of the induction heating equipment.

[0032] Step 2: Adjust the position of the induction heaters, place the four induction heaters close to the working raceway surface of the workpiece, and evenly distribute the four induction heaters around the center of the workpiece.

[0033] The working raceway surface of the workpiece is located at the inner wall or outer wall of the workpiece, that is, when the workpiece is an outer ring, such as Figure 3 As shown, since the working surface of the outer ring is located in the inner wall direction, the induction heater 3 moves to the inner position of the outer ring, and the specific workpiece raceway surface is Figure 3 The position of surface a shown in the figure; when the workpiece is an inner ring, Figure 4 As shown, since the working surface of the inner ring is located in the direction of the outer wall, the induction heater 3 moves to the outer position of the inner ring, and the specific workpiece raceway surface is Figure 4 The positions of surfaces b and c are shown, where surface c is the rib area that contacts the end surface of the rolling element.

[0034] Step 3: Start the induction heating equipment, that is, use the motor to drive the support roller 6 to rotate, and then drive the workpiece above the support roller 6 to rotate, so that the workpiece rotates at high speed around its own central axis. During the rotation of the workpiece, start the induction heater 3, and use the induction heater 3 to heat the working raceway surface of the workpiece. When the workpiece rotates, the real-time temperature of the working raceway surface is monitored by the thermometer 4. Since the workpiece is in a rotating state and four groups of induction heaters 3 are used to heat the working surface, different positions of the working raceway surface of the workpiece can be heated evenly and heated at the same time, avoiding the problem of local temperature being too high or too low, and then preventing the problem of soft band area and excessive deformation after quenching.

[0035] Step 4: When the temperature of the working raceway surface reaches a certain value, the induction heater 3 stops heating, and the workpiece stops rotating. The induction heater 3 moves to a position that does not affect the up and down movement of the workpiece, that is, stops heating the workpiece.

[0036] Step 5: After the workpiece stops rotating, control the induction heating equipment to make the workpiece move vertically downward, so that it is immersed in the coolant in the cooling pool 1 below, and use the coolant to cool the heated workpiece as a whole. Among them, the workbench 2 can be lifted and lowered under the action of power equipment such as hydraulic cylinders. When the workpiece is heated, the workbench 2 moves down, thereby driving the upper workpiece to descend, so that the workpiece is completely immersed in the coolant. This cooling method can replace the traditional method of heating and cooling during medium-frequency induction heating, and can achieve simultaneous cooling of the working surfaces of various parts of the workpiece, realize the overall quenching process of the workpiece, and further prevent the workpiece from deformation due to uneven cooling.

[0037] Step 6: After cooling is completed, the induction heating equipment is controlled to move the cooled workpiece back to above the coolant in the cooling pool 1 to complete the entire quenching process.

[0038] In this embodiment, since the workpiece material is medium carbon alloy steel (such as 42CrMo, 50Mn, etc.), medium frequency induction surface heating is adopted, specifically, the workpiece is rotated at high speed, and four induction heaters 3 are used to heat the workpiece. On the one hand, it can solve the problem that the core toughness of the workpiece is poor and the impact resistance is weak due to the overall quenching method of traditional hardenable steel (such as GCr15, GCr15SiMn, GCr18Mo, etc.); on the other hand, it can solve the problem that the overall quenching method after carburizing of carburized steel (such as 20Cr2Ni4A, 20Cr2Mn2Mo, etc.) causes serious pollution, long cycle, high cost and great processing difficulty; on the other hand, it solves the problem of soft band after quenching caused by the traditional medium frequency induction surface quenching method; on the other hand, it solves the problem of uneven structure and large heat treatment deformation of the workpiece after quenching caused by the inconsistent working state of the sensor caused by the traditional soft band-free quenching method.

[0039] This method of overall quenching by medium-frequency heating of the slewing bearing enables the final workpiece to have the advantages of good surface wear resistance, high fatigue resistance and core impact resistance after the heat treatment is completed, and the structure, hardness and hardened layer of each part of the workpiece are uniform, so that the workpiece has the advantage of small deformation after heat treatment. In addition, it also has the advantages of low environmental pollution, short production cycle and low cost. After assembly, the overall service life of the slewing bearing is long and the reliability is high.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for medium frequency heating overall surface quenching of a wind turbine TRB main shaft bearing, characterized in that: A workpiece made of medium carbon alloy steel is placed on an induction heating device. By placing several induction heaters close to the working raceway surface of the workpiece, the working raceway surface of the workpiece is heated by the induction heaters during high-speed rotation of the workpiece. When the temperature of the working raceway surface of the workpiece reaches a threshold, the induction heater stops heating and the workpiece stops rotating. The workpiece is then immersed in coolant for overall surface quenching.

2. A method for medium frequency heating overall surface quenching of a wind turbine TRB main shaft bearing according to claim 1, characterized in that: There are four induction heaters, which are evenly distributed around the center axis of the workpiece.

3. The method for medium frequency heating overall surface quenching of a wind turbine TRB main shaft bearing according to claim 1, characterized in that: The workpiece is an inner ring or an outer ring of a TRB main shaft bearing of a wind turbine, and the workpiece material is medium carbon alloy steel; the workpiece is horizontally placed on the induction heating device, and its central axis is perpendicular to the horizontal plane.

4. A method for medium frequency heating overall surface quenching of a wind turbine TRB main shaft bearing according to claim 1, characterized in that: The working raceway surface of the workpiece includes the raceway surface in contact with the outer diameter of the rolling element.

5. A method for medium frequency heating overall surface quenching of a wind turbine TRB main shaft bearing according to claim 4, characterized in that: The working raceway surface of the workpiece also includes a rib surface in contact with the end surface of the rolling element.

6. A method for medium frequency heating overall surface quenching of a wind turbine TRB main shaft bearing according to claim 5, characterized in that: The working raceway surface of the workpiece is located at the inner wall or outer wall of the workpiece.

7. The method for medium frequency heating integral surface quenching of a wind turbine TRB main shaft bearing according to claim 1, characterized in that: When the workpiece is rotating at high speed, the heating temperature of the working raceway surface is monitored in real time using a thermometer.

8. The method for medium frequency heating integral surface quenching of a wind turbine TRB main shaft bearing according to claim 1, characterized in that: The diameter of the workpiece is greater than 1500mm.

9. The method for medium frequency heating integral surface quenching of a wind turbine TRB main shaft bearing according to claim 1, characterized in that: The induction heating equipment includes a cooling pool that can accommodate coolant. The interior of the cooling pool is provided with a workbench that can be raised and lowered. Four movable seats are provided on the surface of the workbench. The four movable seats are evenly distributed around the center of the workbench. The movable seats can move toward the center of the workbench or away from the center of the workbench. Each movable seat is equipped with a horizontally arranged and rotatable supporting roller and a vertically arranged and rotatable limiting roller, and a motor is connected to the end of one of the supporting rollers.

10. A method for medium frequency heating overall surface quenching of a wind turbine TRB main shaft bearing according to claim 9, characterized in that: A stirring rod for stirring the coolant is also provided inside the cooling pool, and a liquid inlet and a liquid outlet are provided on the side wall of the cooling pool.

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