A high-precision machining method for a thin-wall sleeve ring of a wind power planetary carrier tapered roller bearing

Abstract

A kind of high-precision machining method for thin-wall sleeve ring of wind power planetary carrier tapered roller bearing belongs to bearing machining technical field, the big end face of forging is changed from traditional inner side back-to-back to external orientation, the workpiece clamping stiffness is improved, which is beneficial to cutting processing and avoids cutting processing defects;A new turning reference procedure is added, first, the outer diameter of one end is finished as a positioning reference, and the other end is clamped and machined after the outer diameter surface is machined, eliminating the clamping eccentricity and machining error caused by blank deviation from the source;Three-petal and six-petal soft jaw differential grading clamping structure is adopted to eliminate workpiece ovality and roundness error. The invention effectively solves the key problem of thin-wall bearing sleeve ring machining deformation, significantly improves the product machining precision, forming quality and batch production qualification rate, and the method has strong applicability and stability.

Description

Technical Field

[0001] This invention belongs to the field of precision machining technology for bearing machinery, specifically relating to a high-precision machining method for thin-walled rings of wind turbine planetary carrier tapered roller bearings. It is applicable to the batch high-precision machining of thin-walled rings of wind turbine planetary carrier tapered roller bearings, and is particularly suitable for machining scenarios where precise control of ellipticity and roundness errors of thin-walled rings is required. Background Technology

[0002] Planetary bearings for wind turbines are core transmission and load-bearing components of wind turbine generator sets. These bearings are mostly ultra-thin-walled structures, characterized by large outer diameters, thin walls, and extremely poor radial rigidity, making them extremely difficult to machine. Tapered roller bearings have very low radial rigidity ratios in their thin-walled rings, making them highly susceptible to deformation during machining due to clamping forces, cutting forces, cutting heat, and residual stress, leading to severe errors in contour accuracy.

[0003] Traditional machining methods have several core defects: First, traditional composite forgings use a back-to-back clamping method with large end faces, resulting in insufficient workpiece clamping rigidity. This makes the workpiece prone to loosening and vibration during machining, severely affecting cutting accuracy and easily causing machining defects such as uneven end faces and cutting deviations. Second, traditional machining uses ordinary rigid three-jaw chucks, which have a small clamping contact area and concentrated force, making the workpiece prone to triangular round contour deformation and causing serious roundness errors. Third, traditional machining methods lack a dedicated benchmark correction process and rely directly on the blank shape for clamping. However, the blank itself has dimensional and shape deviations, which easily cause clamping eccentricity, leading to non-compliance with workpiece coaxiality and roundness standards, and prominent problems such as elliptic errors and edge roundness deformation.

[0004] Patent CN202310254732 discloses a method for machining the outer ring of a thin-walled tapered roller bearing. By optimizing the machining process, it solves the technical problem of low machining accuracy due to large deformation during machining. This solution first integrates two outer rings into a single forging for rough machining, then optimizes the finish machining process by using a secondary clamping reference to control the geometric accuracy of the product's outer diameter. However, this solution only adds a secondary clamping reference; it still uses ordinary rigid clamps. Even with increased clamping width, it cannot solve the problem of achieving high geometric accuracy for the outer diameter of extra-large thin-walled products.

[0005] In summary, for thin-walled raceways of wind turbine planetary carrier tapered roller bearings, there is an urgent need to develop a high-precision machining method that can eliminate elliptic and roundness errors in layers. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a high-precision machining method for thin-walled rings of wind turbine planetary carrier tapered roller bearings. Through a comprehensive approach involving differentiated fixture combinations, process reconfiguration, and stress grading release, various contour errors of thin-walled workpieces are eliminated layer by layer, significantly improving bearing machining accuracy and batch production stability.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a high-precision machining method for thin-walled rings of wind turbine planetary carrier tapered roller bearings, comprising the following machining steps: S1. Rough machining of composite forgings: Rough turning is performed on the end face, outer diameter and raceway of the two-in-one composite forgings to remove the oxide scale and most of the machining allowance, and to trim the basic shape of the workpiece. S2. Stress-relief annealing: Stress-relief annealing is performed on the rough-machined workpiece to eliminate residual stress in the forging and cutting stress during rough machining, and to avoid deformation caused by stress release during subsequent finishing. S3, First semi-finish turning: Use a three-lobed soft jaw chuck to hold the outer diameter of the workpiece, turn half of the outer diameter of the workpiece and simultaneously machine the large end face; S4. Second semi-finish turning: Keep the three-lobed soft jaw chuck tooling unchanged, clamp the already machined half of the outer diameter, unify the positioning datum, and turn the remaining half of the outer diameter. S5. First precision turning: The workpiece outer diameter is clamped by a precision-repaired six-lobed soft jaw chuck, with multiple points of uniform force, and half of the outer diameter is turned, while the large end face and chamfer are simultaneously finished. S6. Second precision turning: Use a six-lobed soft jaw to hold the already precision-turned half of the outer diameter, and turn the remaining half of the outer diameter to eliminate the odd wave error and roundness deviation of the workpiece's triangular circle, and ensure the overall contour accuracy and coaxiality of the outer diameter. S7. Cutting process: The finished two-in-one forging is cut and separated to obtain a single bearing workpiece; S8. Finishing and finishing: Perform precision machining on the small end face, raceway, and inner and outer chamfers of a single workpiece to remove burrs and complete the precision preparation of the finished product.

[0008] In step S2, the stress-relief annealing temperature is 550~650℃, the holding time is 2~4h, and the furnace is slowly cooled to room temperature to completely eliminate the internal stress of metal cutting and the residual stress of forging.

[0009] The three-lobed soft claw chuck in steps S3 and S4 is used for the semi-finishing process. It adopts a flexible buffer clamping structure to adapt to the semi-finishing machining requirements of the workpiece, and is specifically designed to eliminate the elliptical error of the workpiece and avoid the contour stretching deformation caused by the stress of semi-finishing.

[0010] In steps S5 and S6, the six-lobed soft jaw chuck is used for the precision turning process. It adopts a six-point uniform and symmetrical clamping structure, which doubles the number of clamping points and significantly increases the contact area compared to the three-lobed soft jaw. It can evenly distribute the clamping force, effectively correct the roundness error of the workpiece, and improve the overall consistency of outer diameter machining.

[0011] The finishing process employs low-stress cutting parameters and a high-speed cutting, small depth of cut, and small feed rate machining strategy.

[0012] For ultra-thin workpieces with extremely poor rigidity, axial clamping on the end face can be used instead of radial clamping for precision machining, completely avoiding contour deformation caused by radial clamping force and further improving roundness and ellipticity accuracy.

[0013] The beneficial effects of this invention are: Optimize the structure of the forging: Change the orientation of the large end face of the forging from the traditional inner back-to-back to the outer orientation, improve the clamping rigidity of the workpiece, facilitate cutting and avoid cutting defects; Add a turning reference process: use the finished outer diameter of one end as a positioning reference, clamp the already turned outer diameter surface to machine the outer shape of the other end, and eliminate clamping eccentricity and machining error caused by blank deviation from the source. Differentiated graded clamping: The three-lobed soft jaw chuck is used for semi-finishing processes to eliminate workpiece elliptical errors and avoid contour stretching deformation caused by semi-finishing stress; the six-lobed soft jaw chuck is used for finishing processes, adopting a six-point uniform and symmetrical clamping structure, which greatly increases the contact area, can evenly distribute clamping force, effectively correct workpiece roundness errors, and improve the overall consistency of outer diameter machining. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the high-precision machining method of the present invention. Detailed Implementation

[0015] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that the described embodiments are only some embodiments of the present invention, and 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.

[0016] Example 1

[0017] The outer ring of the tapered roller bearing for wind turbine planetary carriers has an outer diameter of φ730mm, a wall thickness of 45mm, and a radial stiffness ratio of 0.023. It is a thin-walled ring that is prone to deformation, requiring high machining accuracy and presenting significant challenges in deformation control. The specific machining steps are as follows: S1. Rough machining of composite forgings: Select two-in-one composite forgings and use ordinary carbide turning tools to rough machine the two end faces, outer circle, and raceway contour of the workpiece. Thoroughly remove oxide scale, forging allowance, and surface defects from the surface of the forging to ensure that the basic shape of the workpiece is flat and to reserve uniform machining allowance for subsequent finishing.

[0018] S2. Graded stress-relief annealing: The workpiece that has completed rough machining and raceway pre-machining is sent into the annealing furnace, the annealing temperature is set to 600℃, the holding temperature is 3h, and the workpiece is naturally cooled to room temperature with the furnace to completely eliminate the forging residual stress and rough machining cutting stress of the forging.

[0019] S3. First semi-finish turning: Use a three-lobed soft jaw chuck to clamp the outer diameter of the workpiece, adjust the chuck pressure to the minimum stable clamping state to avoid excessive extrusion and deformation, turn half of the outer diameter of the workpiece, and simultaneously and accurately adjust the flatness and perpendicularity of the large end face of the workpiece.

[0020] S4. Second semi-finish turning: Keep the three-lobed soft jaw tooling and clamping parameters unchanged, use the already machined half of the outer diameter as the positioning datum, unify the clamping datum, and turn the remaining half of the outer diameter. Through symmetrical step-by-step cutting, completely eliminate the second-order elliptical error of the workpiece caused by the previous machining and blank defects.

[0021] S5. First precision turning: The workpiece outer diameter is evenly clamped by six soft jaws. Relying on the six-point symmetrical pressure equalization structure, the triangular circle deformation caused by the 120° symmetrical force of the three jaws is avoided. High speed, small depth of cut and small feed parameters are used to turn half of the outer diameter, and the high-precision finishing of the large end face and outer peripheral chamfer is completed simultaneously.

[0022] S6. Second precision turning: Using the already precision-turned half of the outer diameter as a precise positioning reference, the six-lobed soft jaws stably hold the workpiece and turn the remaining half of the outer diameter to correct the residual roundness error and high-order ripple error of the workpiece, ensuring that the overall circular contour of the workpiece is uniform and the coaxiality of the outer diameter meets the standard.

[0023] S7. Cutting process: Using special precision cutting tools, the finished two-in-one forging is precisely cut and separated to ensure that the cut surface is flat, without chipping or deformation, and to obtain a single independent bearing workpiece.

[0024] S8. Finishing and finishing: Perform final finishing on the small end face, raceway working surface and inner and outer chamfers of a single bearing workpiece to remove burrs and fine tool marks, optimize the surface quality of the workpiece, and complete the finished product preparation.

[0025] The thin-walled rings of the wind turbine planetary carrier tapered roller bearings processed by this method have a roundness error of ≤0.2mm, an ellipticity error of ≤0.2mm, and the end face flatness, outer diameter accuracy, and raceway accuracy all meet the product requirements. The batch processing qualification rate has been increased from 60% to 90% with the traditional method. The workpieces have no obvious clamping deformation, cutting deformation, or stress deformation, and the processing accuracy and batch stability have been greatly improved.

[0026] 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 principles of the present invention should be included within the protection scope of the present invention.

[0027] The parts of this invention not described in detail are prior art.

Claims

1. A method for high-precision machining of thin-walled rings in a wind turbine planetary carrier tapered roller bearing, characterized in that: The processing steps include the following: S1. Rough machining of composite forgings: Rough turning is performed on the end face, outer diameter and raceway of the two-in-one composite forgings to remove the oxide scale and most of the machining allowance, and to trim the basic shape of the workpiece. S2. Stress-relief annealing: Stress-relief annealing is performed on the rough-machined workpiece to eliminate residual stress in the forging and cutting stress during rough machining, and to avoid deformation caused by stress release during subsequent finishing. S3, First semi-finish turning: Use a three-lobed soft jaw chuck to hold the outer diameter of the workpiece, turn half of the outer diameter of the workpiece and simultaneously machine the large end face; S4. Second semi-finish turning: Keep the three-lobed soft jaw chuck tooling unchanged, clamp the already machined half of the outer diameter, unify the positioning datum, and turn the remaining half of the outer diameter. S5. First precision turning: The workpiece outer diameter is clamped by a precision-repaired six-lobed soft jaw chuck, with multiple points of uniform force, and half of the outer diameter is turned, while the large end face and chamfer are simultaneously finished. S6. Second precision turning: Use a six-lobed soft jaw to hold the already precision-turned half of the outer diameter, and turn the remaining half of the outer diameter to eliminate the odd wave error and roundness deviation of the workpiece's triangular circle, and ensure the overall contour accuracy and coaxiality of the outer diameter. S7. Cutting process: The finished two-in-one forging is cut and separated to obtain a single bearing workpiece; S8. Finishing and finishing: Perform precision machining on the small end face, raceway, and inner and outer chamfers of a single workpiece to remove burrs and complete the precision preparation of the finished product.

2. The method for high-precision machining of thin-walled rings of a wind turbine planetary carrier tapered roller bearing according to claim 1, characterized in that: In step S2, the stress-relief annealing temperature is 550~650℃, the holding time is 2~4h, and the furnace is slowly cooled to room temperature to completely eliminate the internal stress of metal cutting and the residual stress of forging.

3. The high-precision machining method for thin-walled rings of a wind turbine planetary carrier tapered roller bearing according to claim 1, characterized in that: The three-lobed soft claw chuck in steps S3 and S4 is used for the semi-finishing process. It adopts a flexible buffer clamping structure to adapt to the semi-finishing machining requirements of the workpiece, and is specifically designed to eliminate the elliptical error of the workpiece and avoid the contour stretching deformation caused by the stress of semi-finishing.

4. The high-precision machining method for thin-walled rings of a wind turbine planetary carrier tapered roller bearing according to claim 1, characterized in that: In steps S5 and S6, the six-lobed soft jaw chuck is used for the precision turning process. It adopts a six-point uniform and symmetrical clamping structure, which doubles the number of clamping points and significantly increases the contact area compared to the three-lobed soft jaw. It can evenly distribute the clamping force, effectively correct the roundness error of the workpiece, and improve the overall consistency of outer diameter machining.

5. The high-precision machining method for thin-walled rings of a wind turbine planetary carrier tapered roller bearing according to claim 1, characterized in that: In step S6, the soft jaw in-situ finishing process, the clamping force adopts the minimum stable clamping force, which only ensures that the workpiece does not slip or loosen, and avoids excessive clamping that causes extrusion deformation. After finishing, the working surface of the soft jaw is completely in arc-shaped contact with the outer diameter of the workpiece, with no point contact and no gap deviation.

6. The method for high-precision machining of thin-walled rings of a wind turbine planetary carrier tapered roller bearing according to claim 1, characterized in that: The finishing process employs low-stress cutting parameters and a high-speed cutting, small depth of cut, and small feed rate machining strategy.

7. The method for high-precision machining of thin-walled rings of a wind turbine planetary carrier tapered roller bearing according to claim 1, characterized in that: For ultra-thin workpieces with extremely poor rigidity, axial clamping on the end face can be used instead of radial clamping for precision machining, completely avoiding contour deformation caused by radial clamping force and further improving roundness and ellipticity accuracy.

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