Treatment process for check ring of main shaft structural part of wind driven generator

Abstract

The invention provides a treatment process for a check ring of a main shaft structural part of a wind driven generator, relates to the field of heat treatment processes, and aims to solve the problems of over-high hardness and deformation of the check ring with larger radial thickness after heat treatment at present by controlling the temperature change speed and the temperature duration in the heat treatment process. It is ensured that the processed workpiece can achieve the expected hardness range, control over the highest and lowest temperature difference in the heating area in the heat preservation period is beneficial to reduction of deformation caused by the temperature gradient, and the workpiece subjected to heat treatment can meet the requirements for hardness and precision.

Description

Technical Field

[0001] The invention relates to the field of heat treatment technology, and in particular to a treatment technology for a retaining ring of a main shaft structure of a wind turbine generator. Background Art

[0002] The retaining ring is an important structural component of the main shaft inside the nacelle of the wind turbine. The main shaft and its components are a key link in the wind turbine transmission chain. The main shaft is connected to the wind wheel in front and the gearbox in the back to transmit low-speed, high-torque mechanical energy. The shaft end retaining ring is installed between the shaft end and the bearing to prevent the bearing from coming out, stabilize the shaft end position, protect the bearing and the bearing seat, and ensure the safe and stable operation of the wind turbine bearing.

[0003] The commonly used retaining ring is an annular structural part, which is made of 45 steel and has a thickness T of 130mm to 150mm. In its manufacturing process, it needs to be subjected to overall quenching and tempering heat treatment (quenching and tempering) after rough turning to eliminate the stress of rough turning and soften the material, thereby improving the structural stability and facilitating subsequent fine processing. During the quenching and tempering heat treatment, due to its large thickness, the workpiece structure is easy to deform, the workpiece hardness is easy to exceed the standard, and the workpiece after heat treatment is easy to rust, resulting in the scrapping of the workpiece or increasing the difficulty of subsequent fine processing. A quenching and tempering heat treatment method for bearing sleeve processing is disclosed in a Chinese patent (publication number CN 107385187 A), which reduces the temperature drop rate during quenching, reduces the temperature difference between the inside and outside of the bearing sleeve, avoids surface fracture during quenching, improves the quenching quality, improves the bearing sleeve hardness and surface wear resistance of the bearing sleeve, and increases the adaptability of the bearing sleeve. For the retaining ring of the main shaft of a wind turbine generator, the excessive temperature gradient during the insulation period will cause the deformation of the thicker retaining ring, and the excessive hardness will also affect the difficulty of subsequent processing, resulting in the difficulty of processing accuracy to meet the requirements. Summary of the invention

[0004] The purpose of the present invention is to address the defects of the prior art and provide a wind turbine main shaft structural member retaining ring processing process. By controlling the temperature change rate and temperature duration during the heat treatment process, it is ensured that the treated workpiece can reach the expected hardness range. The control of the maximum and minimum temperature difference in the heating zone during the insulation period helps to reduce the deformation caused by the temperature gradient, so that the workpiece after heat treatment can meet the hardness and precision requirements.

[0005] In order to solve the above problems, the following solutions are adopted:

[0006] A wind turbine main shaft structural member retaining ring processing process, comprising:

[0007] Place the workpiece in the heating zone so that there is a gap between the workpiece and the inner wall of the heating zone;

[0008] Heat the workpiece and control the heating rate and temperature in stages;

[0009] After the temperature reaches the set value, the workpiece is quenched and kept warm;

[0010] The workpiece after quenching and holding is quenched, and then tempered, and the tempering holding time is controlled based on the quenching holding time;

[0011] After tempering and insulation, cool to room temperature in air and apply anti-rust oil.

[0012] Furthermore, a plurality of equal-height pads are evenly arranged on the bottom surface of the heating zone, and the end of the workpiece with a larger axial diameter faces the bottom surface of the heating zone and is placed on a plurality of equal-height pads to keep the workpiece stable.

[0013] Furthermore, the equal-height pads maintain stable support for the workpiece after being heated, and after the workpiece is placed in the heating zone, the heating zone is sealed.

[0014] Furthermore, the stepwise control of the heating rate and temperature during the heating process includes:

[0015] Before the temperature of the heating zone reaches the first set temperature, the temperature of the heating zone is increased to the first set temperature at a first heating rate;

[0016] The heating zone is raised to a second set temperature at a second heating rate and enters a quenching and heat preservation stage;

[0017] The second set temperature is higher than the first set temperature.

[0018] Furthermore, the first set temperature is 400° C., the second set temperature is 840° C., and the second heating rate is less than or equal to 220° C. / h.

[0019] Furthermore, the quenching and heat preservation of the workpiece includes: controlling the quenching and heat preservation temperature to be a third set temperature, and during quenching and heat preservation, the difference between the highest temperature and the lowest temperature in the heating zone is less than or equal to 80°C.

[0020] Furthermore, the tempering temperature is a fourth set temperature, and during tempering and heat preservation, the difference between the highest temperature and the lowest temperature in the heating zone is less than or equal to 50°C.

[0021] Furthermore, the tempering holding time is 1.5 times the quenching holding time.

[0022] Furthermore, the quenching medium is water, and a box-type quenching furnace is used.

[0023] Furthermore, when the workpiece is heated, the temperature difference within any set length in the heating zone is controlled to be less than or equal to 100°C.

[0024] Compared with the prior art, the present invention has the following advantages and positive effects:

[0025] (1) In view of the problems of excessive hardness and deformation of retaining rings with larger radial thickness after heat treatment, the temperature change rate and temperature duration during the heat treatment process are controlled to ensure that the treated workpiece can reach the expected hardness range. The control of the maximum and minimum temperature difference in the heating zone during the insulation period helps to reduce the deformation caused by the temperature gradient, so that the workpiece after heat treatment can meet the hardness and precision requirements.

[0026] (2) Multiple equal-height pads are evenly arranged on the bottom surface of the heating zone to provide stable support for the workpiece, with the end with the larger diameter facing downward to prevent deformation during heating and insulation in the heating zone.

[0027] (3) The process parameters and procedures are designed and optimized to ensure the quality of heat treatment, the deformation is within the reserved tolerance for processing, the hardness meets the standard, and the short-term corrosion protection facilitates subsequent fine processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0029] Figure 1 Schematic diagram of the wind turbine main shaft structural member retaining ring processing process in Example 1 of the present invention.

[0030] Figure 2 Schematic diagram of the retaining ring in Example 1 of the present invention. DETAILED DESCRIPTION

[0031] Example 1

[0032] In a typical embodiment of the present invention, Figure 1-Figure 2 As shown, a wind turbine main shaft structural member retaining ring processing process is provided.

[0033] like Figure 1 As shown, the wind turbine main shaft structural member retaining ring processing process includes:

[0034] Place the workpiece in the heating zone so that there is a gap between the workpiece and the inner wall of the heating zone;

[0035] Heat the workpiece and control the heating rate and temperature in stages;

[0036] After the temperature reaches the set value, the workpiece is quenched and kept warm;

[0037] The workpiece after quenching and holding is quenched, and then tempered, and the tempering holding time is controlled based on the quenching holding time;

[0038] After tempering and insulation, cool to room temperature in air and apply anti-rust oil.

[0039] In this embodiment, the workpiece is a super thick retaining ring made of 45 steel with a radial thickness of 130mm to 150mm. The furnace bottom is leveled with equal height pads, and the retaining ring workpiece is placed on the equal height pads with the large end face facing downwards and evenly placed. It is first quenched at 840℃ and water-cooled in a box-type quenching furnace, and then tempered at 600℃ in a hot air circulation tempering furnace, and rust-proof oil is applied for short-term corrosion protection. After the above treatment process, the hardness reaches HB220-260, and the above process flow is more convenient to operate, and subsequent fine turning is convenient.

[0040] Combination Figure 1 and Figure 2 , the wind turbine main shaft structural parts retaining ring processing process includes:

[0041] (1) Preparation: Arrange multiple equal-height pads evenly on the bottom surface of the heating zone. The end with the larger diameter of the workpiece in the axial direction faces the bottom surface of the heating zone and is placed on multiple equal-height pads to keep the workpiece stable.

[0042] In addition, the equal height pads maintain stable support for the workpiece after being heated, and after the workpiece is placed in the heating zone, the heating zone is closed.

[0043] Specifically, the workpiece support surface is leveled, the distance between the workpiece and the furnace bottom, furnace wall and the workpiece is ≥100mm, it remains stable and does not deform when heated; the temperature entering the furnace is not higher than 300℃, and after the workpiece enters the furnace, the furnace door and other places are sealed with thermal insulation cotton to prevent affecting the furnace temperature, which also helps to shorten the heating time and improve the heat treatment efficiency.

[0044] The workpiece can be placed stably during the heating process, avoiding deformation or stress concentration of the workpiece due to uneven supporting surface, which helps to maintain the shape accuracy and uniformity of the internal structure of the workpiece.

[0045] By controlling the spacing between the workpiece and other structures except equal-height pads and maintaining a sufficient distance, heat conduction between the workpiece and other components in the furnace can be reduced, local overheating or uneven temperature can be avoided, which helps to achieve a more uniform heating effect and improve the performance consistency of the workpiece after quenching.

[0046] (2) Heating: The heating rate and temperature during the heating process are controlled in stages. Before the temperature of the heating zone reaches the first set temperature, the temperature of the heating zone is raised to the first set temperature at a first heating rate; the heating zone is raised to the second set temperature at a second heating rate, and then the quenching and heat preservation process is started; wherein the second set temperature is higher than the first set temperature.

[0047] In this embodiment, the first set temperature is 400°C, the first heating rate is 200°C / h, the corresponding heating time is 2h, the second set temperature is 840°C, and the second heating rate is less than or equal to 220°C / h; taking the second heating rate of 210°C / h as an example, the corresponding second heating time is 2h.

[0048] Specifically, according to the operating requirements, the power is turned on to increase the temperature, and it is ensured that the overall temperature rises evenly; before the temperature reaches 400°C, the heating rate is (200°C / h) and the heating time is (2h). When the temperature in the furnace reaches 400°C, the automatic curve recorder of the heat treatment is turned on to record the temperature and time of the heat treatment process. After the temperature reaches 400°C, the heating rate shall not exceed 220°C / h until the temperature reaches 840°C.

[0049] (3) Insulation: The workpiece is quenched and insulated after being heated, and the quenching and insulation temperature is controlled to be the third set temperature. During quenching and insulation, the difference between the highest temperature and the lowest temperature in the heating zone is less than or equal to 80°C.

[0050] In this embodiment, the third set temperature is 840±10°C.

[0051] Specifically, when the temperature reaches 840℃, it starts to enter the insulation state; the insulation temperature is 840±10℃, the quenching insulation time is 4h, and during the insulation, the difference between the highest and lowest temperatures in the heating zone shall not exceed 80℃. The quenching insulation time is set to 4 hours to ensure that the material can be fully austenitized and provide good conditions for subsequent quenching. In addition, the difference between the highest and lowest temperatures in the heating zone is strictly controlled, which helps to ensure that the material obtains a more uniform organizational structure during the austenitization process.

[0052] (4) Cooling: The furnace temperature is 840℃, and water-cooled quenching is performed in a box-type quenching furnace to ensure rapid cooling and obtain a high-hardness martensitic structure.

[0053] (5) Tempering: The tempering temperature is the fourth set temperature. During tempering and heat preservation, the difference between the highest temperature and the lowest temperature in the heating zone is less than or equal to 50°C.

[0054] Specifically, a hot air circulation tempering furnace is used, the fourth set temperature is the tempering temperature of 600°C±10°C, the holding time is 6 hours, the tempering holding time = 1.5 times the quenching holding time, and the selection of the time ratio is helpful to obtain ideal mechanical properties and organizational structure; it is taken out of the furnace at 600°C and cooled to room temperature in still air.

[0055] (6) Apply anti-rust oil.

[0056] Through precise quenching and tempering processes, the 45 steel retaining ring is ensured to reach the expected hardness range (HB220-260), while obtaining good comprehensive mechanical properties such as strength, toughness and fatigue resistance. Strict control of temperature uniformity and heating and cooling rates effectively reduces deformation and cracking caused by temperature stress and improves the yield rate of workpieces.

[0057] During the operation of the wind turbine generator set, the main shaft and the retaining ring need to bear huge loads and alternating stresses, so the material is required to have high strength and good toughness to ensure the safe and stable operation of the unit. In this embodiment, through reasonable heat treatment and anti-rust measures, the corrosion resistance and fatigue resistance of the retaining ring are improved, and the retaining ring has high strength and good toughness, thereby extending the service life of the main shaft of the wind turbine generator set.

[0058] In step (2), when heating, the temperature difference within any 4500 mm length in the heating zone is ≤100°C.

[0059] In addition, in order to ensure the heat treatment effect and reduce deformation caused by excessive temperature gradient, the maximum and minimum temperature difference in the heating zone during quenching and tempering of the workpiece should be ≤50℃.

[0060] After quenching and tempering heat treatment, apply anti-rust oil for short-term corrosion protection to prevent rust and facilitate subsequent fine processing.

[0061] In the wind turbine main shaft structural member retaining ring processing process, in the heating stage, the second heating rate is controlled to be: 55°C / h≤second heating rate≤220°C / h, after the tempering and insulation is withdrawn from the heating zone at 600°C, the tempering cooling rate is controlled to be: 55°C / h≤tempering cooling rate≤280°C / h, the minimum quenching and insulation time is 1.5h+0.01T, and the tempering and insulation time = 1.5 times the quenching and insulation time; wherein T is the heat treatment thickness of the workpiece; therefore, the wind turbine main shaft structural member retaining ring processing process provided in this embodiment has low energy consumption, low cost and good effect.

[0062] Unnecessary energy consumption is reduced by precisely controlling the heating rate, holding temperature and tempering temperature. A slower heating rate is used in the heating stage before 400°C, which helps to reduce energy consumption. The design of the hot air circulation tempering furnace allows heat energy to circulate more efficiently in the furnace, improving energy utilization.

[0063] In this embodiment, 6 equal-height pads are set at the bottom of the furnace to level it, and the large end of the retaining ring is placed on the equal-height pads with its large end facing downward, which ensures the stability of the workpiece during the heat treatment process and reduces deformation caused by uneven heating. During the heating process, special emphasis is placed on the temperature difference control within any 4500mm length in the heating zone, as well as the control of the highest and lowest temperature differences in the heating zone during the insulation period. These measures are helpful in reducing deformation caused by temperature gradients.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A wind turbine main shaft structural member retaining ring processing process, characterized in that: include: Place the workpiece in the heating zone so that there is a gap between the workpiece and the inner wall of the heating zone; Heat the workpiece and control the heating rate and temperature in stages; After the temperature reaches the set value, the workpiece is quenched and kept warm; The workpiece after quenching and holding is quenched, and then tempered, and the tempering holding time is controlled based on the quenching holding time; After tempering and insulation, cool to room temperature in air and apply anti-rust oil.

2. The wind turbine main shaft structural member retaining ring processing process according to claim 1, characterized in that: Multiple equal-height pads are evenly arranged on the bottom surface of the heating zone. The end of the workpiece with a larger axial diameter faces the bottom surface of the heating zone and is placed on multiple equal-height pads to keep the workpiece stable.

3. The wind turbine main shaft structural member retaining ring processing process according to claim 2, characterized in that: The equal height pads maintain stable support for the workpiece after being heated, and after the workpiece is placed in the heating zone, the heating zone is sealed.

4. The wind turbine main shaft structural member retaining ring processing process according to claim 1, characterized in that: The stepwise control of the heating rate and temperature during the heating process includes: Before the temperature of the heating zone reaches the first set temperature, the temperature of the heating zone is increased to the first set temperature at a first heating rate; The heating zone is raised to a second set temperature at a second heating rate and enters a quenching and heat preservation stage; The second set temperature is higher than the first set temperature.

5. The wind turbine main shaft structural member retaining ring processing process according to claim 4, characterized in that: The first set temperature is 400° C., the second set temperature is 840° C., and the second heating rate is less than or equal to 220° C. / h.

6. The wind turbine main shaft structural member retaining ring processing process according to claim 1, characterized in that: The quenching and heat preservation of the workpiece includes: controlling the quenching and heat preservation temperature to be a third set temperature, and during quenching and heat preservation, the difference between the highest temperature and the lowest temperature in the heating zone is less than or equal to 80°C.

7. The wind turbine main shaft structural member retaining ring processing process according to claim 6, characterized in that: The tempering temperature is the fourth set temperature. During tempering and heat preservation, the difference between the highest temperature and the lowest temperature in the heating zone is less than or equal to 50°C.

8. The wind turbine main shaft structure retaining ring processing process according to claim 6 or 7, characterized in that: The tempering holding time is 1.5 times the quenching holding time.

9. The wind turbine main shaft structural member retaining ring processing process according to claim 1, characterized in that: The quenching medium is water, and a box-type quenching furnace is used.

10. The wind turbine main shaft structure retaining ring processing process according to claim 1, characterized in that: When the workpiece is heated, the temperature difference within any set length in the heating zone is controlled to be less than or equal to 100°C.

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