Wind power bearing ring forge piece and heat treatment process

Abstract

The invention provides a wind power bearing ring forge piece and a heat treatment process, and relates to the technical field of forge piece heat treatment, the wind power bearing ring forge piece comprises an inner ring, an outer ring, a raceway area and a non-raceway area; the raceway area is continuously arranged in the circumferential direction of the bearing ring, and an integrally-formed stress diffusion structure is arranged below the raceway area; the mechanical property of the bearing ring is optimized through the design of a stress diffusion structure, a variable cross-section transition area and an annular reinforcing rib, uniform stress dispersion, quenching uniformity improvement and construction of a high-hardness wear-resistant layer on the surface of a raceway are achieved by combining hot rotary swaging shaping, bainite isothermal quenching and a double-stage induction quenching process, the anti-fatigue life is remarkably prolonged, and the comprehensive performance of the material is remarkably improved; the problem of fatigue failure caused by stress concentration, non-uniform quenching hardness and insufficient surface wear resistance of the wind power bearing ring under the action of alternating load is solved.

Description

Technical Field

[0001] This invention relates to the field of heat treatment technology for forgings, and particularly to a wind turbine bearing ring forging and its heat treatment process. Background Technology

[0002] During the finishing stage of bearing products, milling and drilling alter the product's structure and release residual internal stress, leading to elliptical deformation of the finished bearing. There are two main reasons for elliptical deformation of bearing ring forgings during forging and heat treatment. One is that uneven heating, unreasonable heating rates, and uneven cooling processes during heat treatment generate significant internal stress within the forging, causing elliptical deformation after heat treatment. The other reason is that unreasonable or improperly executed process parameters during heat treatment generate significant internal stress within the forging, but the product itself does not deform initially. During finishing, the change in product structure leads to a significant release of this internal stress, resulting in deformation.

[0003] Currently, the existing forging and heat treatment processes for wind turbine bearing rings present challenges such as stress concentration, uneven quenching hardness, and fatigue failure due to insufficient surface wear resistance under alternating loads. Summary of the Invention

[0004] This invention relates to a wind turbine bearing ring forging and its heat treatment process. By optimizing the mechanical properties of the bearing ring through stress diffusion structure, variable cross-section transition zone and annular reinforcing rib design, and combining hot rotary forging, bainitic isothermal quenching and two-stage induction hardening processes, it achieves uniform stress dispersion, improved quenching uniformity and construction of a high-hardness wear-resistant layer on the raceway surface, significantly enhancing fatigue life and overall material performance.

[0005] In a first aspect, the present invention provides a wind turbine bearing ring forging and a heat treatment process, specifically including: an inner ring, an outer ring, a raceway area, and a non-raceway area; The raceway area is continuously arranged along the circumference of the bearing ring, and an integrally formed stress diffusion structure is provided below the raceway area.

[0006] Furthermore, the inner wall of the inner ring is provided with concentric annular reinforcing ribs, which divide the inner cavity of the ring into multiple chambers, and the reinforcing ribs are provided with flow guide holes.

[0007] Furthermore, the non-raceway region is provided with a variable cross-section transition zone extending axially or radially, so that the bearing ring forms a thickness gradient distribution in the axial or radial direction to reduce the stress concentration of alternating loads generated during wind power operation and improve the fatigue life of the bearing ring.

[0008] A wind turbine bearing ring forging and its heat treatment process, comprising the following steps; Forging billet preparation and heating: The alloy steel forging billet is heated to 1150℃~1260℃ and held at that temperature; Forging and ring rolling: The forging billet is upset, drawn, punched and enlarged, and then rolled into a ring. Hot rotary forging shaping: During or after ring rolling, a cemented carbide hot rotary forging head with multiple degrees of freedom is used to rotate and forge the inner and outer walls of the ring forging to refine the grains and form an irregular cross section. Heat treatment: The shaped ring forgings are quenched and tempered. Furthermore, the quenching in the heat treatment step is induction quenching for the bearing raceway, which includes: first induction heating the raceway to 890℃~920℃, then performing a second induction heating to 860℃~890℃ after an interval of 15~20 minutes, and starting cooling treatment within 50~100 seconds after the second heating ends; the cooling treatment is carried out using compressed air at a pressure of 1.5~2MPa or segmented spray coolant.

[0009] Furthermore, the temperature of the hot rotary forging and shaping step is controlled within the range of 800℃ to 930℃, and then the residual heat of the ring forging is used to directly perform quenching treatment to achieve residual heat quenching.

[0010] Furthermore, the quenching in the heat treatment step is bainitic isothermal quenching, the specific process of which is as follows: after heating the ring forging to 850℃~870℃ for austenitization, it is placed in a nitrate bath at 220℃~240℃ for isothermal treatment for 25~30 hours.

[0011] Furthermore, in the heat treatment step, the ring forging is fixed by limiting fixtures during austenitization and isothermal quenching, and the nitrate bath is in a top-down circulating flow state.

[0012] Furthermore, the hot forging head rotates at a speed of not less than 60 rpm and moves radially and axially along the ring forging in a stepping manner, with a single-turn reduction of not less than 5%.

[0013] This invention provides a wind turbine bearing ring forging and its heat treatment process, which has the following beneficial effects: In this invention, the stress diffusion structure is integrally molded to achieve uniform stress distribution in the raceway region. Combined with the thickness gradient distribution formed by the variable cross-section transition zone, the stress concentration caused by wind power alternating loads is effectively reduced, thus improving the fatigue life of the bearing ring. The annular reinforcing ribs and guide holes work together to enhance the radial stiffness of the ring body and guide the flow of cooling medium in a directional manner, optimizing the quenching uniformity and hardness gradient control. In terms of heat treatment process, hot rotary forging with a speed of ≥60 rpm and a reduction of ≥5% is used to refine the grains and accurately form the irregular cross-section in the range of 800℃~930℃. Combined with isothermal quenching of bainitic material in a 220℃~240℃ nitrate bath, the quenching uniformity is ensured. Finally, a high-hardness wear-resistant layer is constructed on the raceway surface through two-stage heating (890℃~920℃→860℃~890℃) and rapid cooling of 1.5~2MPa, which comprehensively improves the mechanical properties and wear resistance of the material.

[0014] In addition, the stress diffusion structure achieves uniform stress distribution in the raceway area through an integral molding, thereby improving the fatigue life of the bearing ring; the variable cross-section transition zone extends along the axial / radial direction to form a thickness gradient distribution, effectively reducing stress concentration caused by alternating loads during wind power operation; the annular reinforcing ribs and the guide holes work together to enhance the radial stiffness of the ring body and promote the directional flow of the cooling medium during heat treatment, optimizing the quenching uniformity and hardness gradient control.

[0015] Furthermore, the hot rotary forging process employs a rotation speed of ≥60 rpm and a single-turn reduction of ≥5%, achieving grain refinement and precise forming of irregular cross-sections within a temperature range of 800℃~930℃, thereby improving the mechanical properties of the material. Bainitic isothermal quenching is achieved through a 220℃~240℃ nitrate bath circulation flow, ensuring quenching uniformity and improving hardness and toughness. Induction hardening utilizes dual-stage heating (890℃~920℃→860℃~890℃) and rapid cooling with 1.5~2MPa compressed air / segmented coolant, achieving the construction of a high-hardness wear-resistant layer on the raceway surface. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below.

[0017] The accompanying drawings described below are only related to some embodiments of the invention and are not intended to limit the invention.

[0018] In the attached diagram: Figure 1 This is a schematic diagram of the wind turbine bearing ring forging of the present invention.

[0019] Figure 2 This is a schematic diagram of the heat treatment process for the wind turbine bearing ring forging of the present invention.

[0020] Figure 3This is a schematic diagram of the heat treatment process steps for the wind turbine bearing ring forging of the present invention.

[0021] Figure 4 This is a schematic diagram of the isothermal quenching process for the heat treatment of the wind turbine bearing ring forging of the present invention.

[0022] List of reference numerals 1. Inner ring; 2. Outer ring; 3. Raceway area; 4. Non-raceway area. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the described 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.

[0024] Please refer to Figures 1 to 4 As shown: Example 1: The present invention provides a wind turbine bearing ring forging, including an inner ring (1), an outer ring (2), a raceway area (3) and a non-raceway area (4). The raceway area (3) is continuously arranged along the circumferential direction of the bearing ring, and an integrally formed stress diffusion structure is provided below the raceway area (3).

[0025] The non-raceway region (4) is provided with a variable cross-section transition zone extending axially or radially, so that the bearing ring forms a thickness gradient distribution in the axial or radial direction to reduce the stress concentration of alternating loads generated during wind power operation and improve the fatigue life of the bearing ring. The inner wall of the inner ring (1) is provided with concentric annular reinforcing ribs, which divide the inner cavity of the ring into multiple chambers, and the reinforcing ribs are provided with guide holes. Specifically, the stress diffusion structure achieves uniform dispersion of stress in the raceway region through integral molding, thereby improving the fatigue life of the bearing ring. The variable cross-section transition zone extends axially / radially to form a thickness gradient distribution, which effectively reduces the stress concentration caused by alternating loads during wind power operation. The annular reinforcing ribs and guide holes work together to enhance the radial stiffness of the ring and promote the directional flow of the cooling medium during heat treatment, thereby optimizing the quenching uniformity and hardness gradient control.

[0026] One of the wind turbine bearing ring forgings and heat treatment processes includes the following steps; Forging billet preparation and heating: The alloy steel forging billet is heated to 1150℃~1260℃ and held at that temperature; Forging and ring rolling: The forging billet is upset, drawn, punched and enlarged, and then rolled into a ring. Hot rotary forging shaping: During or after ring rolling, a cemented carbide hot rotary forging head with multiple degrees of freedom is used to rotate and forge the inner and outer walls of the ring forging to refine the grains and form an irregular cross section. Heat treatment: The shaped ring forgings are quenched and tempered.

[0027] The hot forging head rotates at a speed of not less than 60 rpm and moves radially and axially along the ring forging in a stepping manner. The single-turn reduction is not less than 5%. The temperature of the hot forging forming step is controlled within the range of 800℃~930℃. Then, the residual heat of the ring forging is used to directly perform quenching treatment to achieve residual heat quenching.

[0028] In this embodiment of the invention, the quenching in the heat treatment step is bainitic isothermal quenching. The specific process is as follows: after heating the ring forging to 850℃~870℃ for austenitization, it is placed in a nitrate bath at 220℃~240℃ for isothermal treatment for 25~30 hours. During the heat treatment step, the ring forging is fixed by limiting fixtures during austenitization and isothermal quenching, and the nitrate bath is in a top-down circulating state.

[0029] Example 2: Based on Example 1, the quenching in the heat treatment step is induction quenching for the bearing raceway, which includes: first induction heating of the raceway to 890℃~920℃, followed by a second induction heating to 860℃~890℃ after an interval of 15~20 minutes, and starting cooling within 50~100 seconds after the second heating; the cooling is performed using compressed air at a pressure of 1.5~2MPa or segmented spray coolant; specifically, the hot rotary forging process uses... With a rotation speed of ≥60 rpm and a single-turn reduction of ≥5%, grain refinement and precise shaping of irregular cross sections are achieved in the temperature range of 800℃~930℃, improving the mechanical properties of the material; bainitic isothermal quenching is achieved through a 220℃~240℃ nitrate bath circulation flow to ensure quenching uniformity and improve hardness and toughness; induction hardening adopts a two-stage heating (890℃~920℃→860℃~890℃) and rapid cooling with 1.5~2MPa compressed air / segmented coolant to achieve the construction of a high-hardness wear-resistant layer on the raceway surface.

[0030] The specific usage and function of this embodiment are as follows: In this invention, the alloy steel forging billet is heated to 1150℃~1260℃ and held at that temperature; the forging billet is upset, drawn, punched, and expanded, and then rolled into a ring; during or after the ring rolling process, a cemented carbide hot rotary forging head with multiple degrees of freedom is used to rotate and forge the inner and outer walls of the ring forging to refine the grains and form an irregular cross-section; and the shaped ring forging is then quenched and tempered; the quenching in the heat treatment step is bainitic isothermal quenching, the specific process of which is: heating the ring forging to 85℃... After austenitization at 0℃~870℃, the bearing is subjected to isothermal treatment in a nitrate bath at 220℃~240℃ for 25~30 hours. The quenching in the heat treatment step is induction hardening for the bearing raceway, which includes: first induction heating of the raceway to 890℃~920℃, followed by a second induction heating to 860℃~890℃ after an interval of 15~20 minutes, and cooling treatment starting within 50~100 seconds after the second heating ends; the cooling treatment is carried out using compressed air at a pressure of 1.5~2MPa or segmented spray coolant.

Claims

1. A wind turbine bearing ring forging, characterized in that, It includes the inner ring (1), the outer ring (2), the raceway area (3), and the non-raceway area (4); The raceway area (3) is continuously arranged along the circumferential direction of the bearing ring, and an integrally formed stress diffusion structure is provided below the raceway area (3).

2. The wind turbine bearing ring forging and heat treatment process according to claim 1, characterized in that: The non-rolling track area (4) is provided with a variable cross-section transition area extending along the axial or radial direction, so that the bearing ring forms a thickness gradient distribution in the axial or radial direction to reduce the stress concentration of alternating loads generated during wind power operation and improve the fatigue life of the bearing ring.

3. The wind turbine bearing ring forging and heat treatment process according to claim 1, characterized in that: The inner wall of the inner ring (1) is provided with concentric annular reinforcing ribs, which divide the inner cavity of the ring into multiple chambers, and the reinforcing ribs are provided with flow guide holes.

4. The heat treatment process steps for a wind turbine bearing ring forging as described in any one of claims 1-3 are as follows: Forging billet preparation and heating: The alloy steel forging billet is heated to 1150℃~1260℃ and held at that temperature; Forging and ring rolling: The forging billet is upset, drawn, punched and enlarged, and then rolled into a ring. Hot rotary forging shaping: During or after ring rolling, a cemented carbide hot rotary forging head with multiple degrees of freedom is used to rotate and forge the inner and outer walls of the ring forging to refine the grains and form an irregular cross section. Heat treatment: The shaped ring forgings are quenched and tempered.

5. The wind turbine bearing ring forging and heat treatment process according to claim 4, characterized in that: The hot forging press head in the hot forging process rotates at a speed of not less than 60 rpm and moves in a stepping manner along the radial and axial direction of the ring forging, with a single-turn reduction of not less than 5%.

6. The wind turbine bearing ring forging and heat treatment process according to claim 4, characterized in that: The temperature of the hot rotary forging and shaping step is controlled within the range of 800℃ to 930℃. Subsequently, the residual heat of the ring forging is used to directly perform quenching treatment to achieve residual heat quenching.

7. The wind turbine bearing ring forging and heat treatment process according to claim 4, characterized in that: The quenching in the heat treatment step is bainitic isothermal quenching, and the specific process is as follows: after heating the ring forging to 850℃~870℃ for austenitization, it is placed in a nitrate bath at 220℃~240℃ for isothermal treatment for 25~30 hours.

8. The wind turbine bearing ring forging and heat treatment process according to claim 4, characterized in that: In the heat treatment process, the ring forging is fixed by limiting fixtures during austenitization and isothermal quenching, and the nitrate bath is in a downward circulating state.

9. The wind turbine bearing ring forging and heat treatment process according to claim 4, characterized in that: The quenching in the heat treatment step is induction quenching for the bearing raceway, which includes: first induction heating the raceway to 890℃~920℃, then performing a second induction heating to 860℃~890℃ after an interval of 15~20 minutes, and starting cooling treatment within 50~100 seconds after the second heating ends; the cooling treatment is carried out with compressed air at a pressure of 1.5~2MPa or segmented spray coolant.

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