Machining method of high-precision thin-wall double-row angular contact ball bearing

Abstract

The invention discloses a machining method for a high-precision thin-wall double-row angular contact ball bearing, belongs to the technical field of machining, and particularly relates to the machining method for the high-precision thin-wall double-row angular contact ball bearing. The invention aims to solve the problems of low precision and surface vibration marks in double-groove processing of the bearing outer ring made of high-temperature heat-resistant steel. The method comprises the following steps: 1, turning; 2, heat treatment; 3, coarse grinding circulation; 4, supplementary tempering; 5, final grinding circulation; sixthly, outer grooves are ground in sequence; 7, finely grinding and processing; 8, detecting and calibrating; and 9, post-processing. The method is used for machining the outer ring of the stainless steel rod end knuckle bearing. By the adoption of the machining method, the position of the double grooves meets 0.015 mm, grinding vibration marks on the surfaces of the grooves are eliminated, and the precision of the product meets the requirements of users.

Description

Technical Field

[0001] This invention belongs to the field of machining technology, specifically relating to a machining method for a high-precision thin-walled double-row angular contact ball bearing. Background Technology

[0002] Double-row angular contact ball bearings, as a key mechanical component with high load-bearing capacity and excellent rotational accuracy, have become core support elements in critical fields such as high-end machine tool spindles, aerospace transmission systems, and precision instruments due to their core advantage of being able to simultaneously withstand radial and bidirectional axial loads. Their machining quality directly determines the operating accuracy, stability, and service life of the end-use equipment. Among them, P4-grade double-row angular contact ball bearings, as high-precision products, have even more stringent requirements for machining accuracy. Their outer ring structure design is particularly unique, employing a symmetrical double-groove layout and integrating flange and notch structures. This complex structure not only requires extremely high standards of dimensional accuracy and geometric tolerances in the raceways but also ensures low surface roughness and a defect-free state on the raceway surface, which is the core key to achieving the overall performance of the bearing.

[0003] The P4-grade double-row angular contact ball bearing uses high-temperature heat-resistant steel as the base material for its outer ring. While this material meets the high-temperature resistance and wear resistance requirements of high-end applications, it also possesses high toughness and strong grinding resistance, posing significant challenges to precision machining. In existing traditional machining processes, the industry commonly employs a method of grinding both grooves simultaneously in a single positioning operation. This aims to simplify the process and improve machining efficiency by reducing the number of positioning operations. However, in practical applications, this method has revealed many intractable defects, severely restricting the improvement of product precision and surface quality.

[0004] Firstly, when grinding the inner surface of the double-groove outer ring of a bearing, the grinding wheel connector must be designed as a slender structure due to the strict limitation of the internal machining space of the outer ring. However, the slender connector has inherently insufficient rigidity and is prone to elastic deformation under the grinding force generated during the grinding process. At the same time, it will cause micro-vibrations under high-speed rotation conditions. This vibration is directly transmitted to the contact interface between the grinding wheel and the workpiece, resulting in an unstable cutting trajectory during the groove grinding process. This not only fails to guarantee the dimensional accuracy and form and position tolerance of the groove, but also forms obvious vibration marks on the groove surface, significantly reducing the surface quality and affecting the lubrication effect and contact stability of the bearing during operation.

[0005] Secondly, the high toughness of high-temperature heat-resistant steel requires a greater grinding force to achieve effective cutting during the grinding process, which further exacerbates the radial load on the grinding wheel shaft and the connecting rod. The increase in radial force not only intensifies the deformation of the connecting rod, but also leads to an increase in the vibration amplitude of the grinding wheel shaft, forming a vicious cycle of increased load, intensified vibration, and decreased accuracy. This seriously affects the stability of the machining process, resulting in poor product accuracy consistency and difficulty in improving the pass rate during mass production.

[0006] Finally, the machining method of grinding two grooves simultaneously in one positioning has inherent limitations in precision control. Since the two grooves are symmetrically distributed in space, it is difficult to accurately control the depth, angle and relative position of the two grooves at the same time during a single positioning process. As a result, the positional tolerances such as coaxiality and parallelism between the two grooves cannot meet the requirements of P4-level high-precision bearings. Exceeding the positional tolerance will cause uneven contact force between the rolling elements and the two grooves after the bearing is assembled, which will lead to problems such as increased operating noise and accelerated wear. This cannot meet the core requirements of high precision and high reliability of bearings in high-end machine tools, aerospace and other fields.

[0007] In summary, traditional machining methods face significant challenges when processing the double-groove outer ring of high-precision thin-walled double-row angular contact ball bearings made of high-temperature heat-resistant steel. These challenges include difficulties in precision control, surface vibration elimination, and poor machining stability. There is an urgent need to develop a new machining method to fundamentally solve these technical problems and meet the pressing demand for high-precision bearings from the high-end equipment manufacturing industry. Summary of the Invention

[0008] The purpose of this invention is to solve the problems of low precision and surface vibration marks in the machining of double grooves on the outer ring of high-temperature heat-resistant steel bearings, and to provide a machining method for high-precision thin-walled double-row angular contact ball bearings.

[0009] The specific steps of the processing method for a high-precision thin-walled double-row angular contact ball bearing of the present invention are as follows:

[0010] 1. Turning: The bearing outer ring blank is turned to form the preliminary outer circle, plane A, plane B and inner circle structure;

[0011] II. Heat treatment: Heat treatment is performed on the machined workpiece;

[0012] III. Rough Grinding Cycle: Rough grinding is performed on the outer circle, plane A, and plane B of the workpiece.

[0013] IV. Supplementary Tempering: Supplementary tempering treatment is performed on the workpiece after rough grinding;

[0014] V. Final Grinding Cycle: Using a high-precision CNC double-end face grinder, process plane A and plane B according to the process of rough grinding plane → fine grinding plane → final grinding plane. Dress the grinding wheel before fine grinding and final grinding. After dressing, grind twice with a small feed rate. After the grinding wheel is stable, grind normally. Control the difference in width and height between products in the same batch to ≤0.003mm.

[0015] VI. Grinding the outer groove in sequence: First, using plane A and the outer circle as positioning references, grind the outer groove I, controlling the deviation of groove position I to be ≤0.01mm; then, using plane B and the outer circle as positioning references, grind the outer groove II.

[0016] VII. Fine grinding process: The fine grinding process is carried out in sequence as follows: rough grinding outer groove I → rough grinding outer groove II → fine grinding outer groove I → fine grinding outer groove II;

[0017] 8. Testing and Calibration: Use a profilometer to test the actual spacing of the channels and adjust the channel position;

[0018] 9. Post-processing: Demagnetize and clean the workpiece to complete the processing.

[0019] The beneficial effects of this invention are:

[0020] This invention employs a two-stage positioning grinding method for the outer groove, coupled with optimized stress distribution using a slender connecting rod, completely eliminating vibration issues inherent in traditional single-stage positioning machining. This completely eliminates surface chatter marks and significantly improves surface quality. Through optimized planar machining processes and control of the difference between the width and height, the problem of out-of-tolerance groove center diameter caused by the two-stage positioning is resolved. The positional tolerance of the two grooves is precisely controlled within 0.015mm, meeting P4-level accuracy requirements. The supplementary tempering process and precise matching of grinding parameters effectively remove machining stress, improving machining stability and product consistency, increasing the batch yield to over 98%. Optimized testing methods ensure real-time monitoring and precise adjustment of the machining process, further guaranteeing product accuracy and making it suitable for large-scale industrial production. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the bearing outer ring structure. Detailed Implementation

[0022] Specific Implementation Method 1: This implementation method for processing a high-precision thin-walled double-row angular contact ball bearing specifically includes the following steps:

[0023] 1. Turning: The bearing outer ring blank is turned to form the preliminary outer circle, plane A, plane B and inner circle structure;

[0024] II. Heat treatment: Heat treatment is performed on the machined workpiece;

[0025] III. Rough Grinding Cycle: Rough grinding is performed on the outer circle, plane A, and plane B of the workpiece.

[0026] IV. Supplementary Tempering: Supplementary tempering treatment is performed on the workpiece after rough grinding;

[0027] V. Final Grinding Cycle: Using a high-precision CNC double-end face grinder, process plane A and plane B according to the process of rough grinding plane → fine grinding plane → final grinding plane. Dress the grinding wheel before fine grinding and final grinding. After dressing, grind twice with a small feed rate. After the grinding wheel is stable, grind normally. Control the difference in width and height between products in the same batch to ≤0.003mm.

[0028] VI. Grinding the outer groove in sequence: First, using plane A and the outer circle as positioning references, grind the outer groove I, controlling the deviation of groove position I to be ≤0.01mm; then, using plane B and the outer circle as positioning references, grind the outer groove II.

[0029] VII. Fine grinding process: The fine grinding process is carried out in sequence as follows: rough grinding outer groove I → rough grinding outer groove II → fine grinding outer groove I → fine grinding outer groove II;

[0030] 8. Testing and Calibration: Use a profilometer to test the actual spacing of the channels and adjust the channel position;

[0031] 9. Post-processing: Demagnetize and clean the workpiece to complete the processing.

[0032] This implementation method employs a sequential machining approach: grinding outer groove I first, then outer groove II. Each grinding operation targets only a single groove, eliminating the need to consider spatial interference from simultaneous machining of two grooves. Compared to traditional single-stage machining, the grinding wheel extension has more space for arrangement, allowing for appropriate increases in diameter or decreases in length while ensuring machining stroke, significantly improving extension stiffness. With increased stiffness, the elastic deformation under grinding force is drastically reduced from the traditional micrometer level to the nanometer level, suppressing vibration at its source.

[0033] In this embodiment, during sequential grinding, the "outer circle + end face" is used as the positioning datum for each step (for grinding outer groove I, plane A + outer circle is used as the datum; for grinding outer groove II, plane B + outer circle is used as the datum), and the accuracy of the positioning datum is strictly controlled (outer circle runout tolerance ≤ 0.002mm, parallelism tolerance between plane A and plane B ≤ 0.001mm). The outer circle serves as the radial datum to ensure the coaxiality of the groove and the outer ring axis; the end face serves as the axial datum to precisely control the axial position of the groove, ensuring that the position deviation of a single groove is ≤ 0.01mm, thus laying the foundation for the position tolerance control of the double groove.

[0034] Optimized control of the relative accuracy of the double grooves in planar machining: Through a three-stage planar machining process of "rough grinding → fine grinding → final grinding," combined with the rigid machining platform of the AC1200F high-precision CNC double-end face grinder, the difference in width and height between products in the same batch is controlled to ≤0.003mm. Width and height is the core related dimension of the double groove spacing. Its accuracy control ensures the consistency of the axial reference during the two positioning grinding operations, avoiding the double groove center diameter deviation caused by end face dimension deviation. Further verification using the formula "groove spacing = width and height - (groove position I + groove position II)" achieves precise control of the double groove position tolerance within 0.015mm, meeting the P4 level accuracy requirements.

[0035] Supplementary tempering eliminates machining stress and ensures precision stability: High-temperature heat-resistant steel is prone to residual stress during machining and rough grinding. If not eliminated in time, stress release during subsequent processing can cause workpiece deformation, affecting precision. This solution adds a 250℃ supplementary tempering process after rough grinding. Through thermal action, the internal stress of the material is released evenly, reducing deformation during subsequent grinding. Simultaneously, the combination of heat treatment and supplementary tempering stabilizes the workpiece's metallographic structure, preventing dimensional drift caused by microstructural changes and ensuring consistent precision during mass production.

[0036] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that a high-quality 89A180KV grinding wheel is used in the processing. Other steps and parameters are the same as in Specific Implementation Method One.

[0037] This implementation method utilizes high-quality 89A180KV grinding wheels, which possess high abrasive hardness and strong wear resistance. Targeting the high toughness of high-temperature heat-resistant steel, it achieves effective cutting with relatively low grinding force, avoiding the surge in grinding force caused by abrasive dulling in traditional grinding wheels. Furthermore, it optimizes the final grinding process parameters (grinding wheel linear speed 20-35 m / s, workpiece shaft speed 150-350 r / min, feed rate 2-4 μm / s), employing a "small feed rate, high speed" grinding strategy to reduce the contact stress between the abrasive grains and the workpiece per unit time, lowering the impact of radial load on the grinding wheel shaft and connecting rod, and preventing exacerbated vibration. During final grinding of the flat surface, the grinding wheel is dressed before fine grinding and final grinding to ensure sharp and uniformly distributed abrasive grains. After dressing, it is ground twice with a small feed rate to allow the grinding wheel to reach a dynamically stable state before normal grinding. This process avoids vibration caused by the initial instability of the grinding wheel, while the stable grinding trajectory ensures uniform cutting of the groove surface, completely eliminating the conditions for vibration marks.

[0038] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One in that the supplementary tempering temperature in step four is 250℃. Other steps and parameters are the same as in Specific Implementation Method One.

[0039] Specific Implementation Method Four: This implementation method differs from Specific Implementation Method One in that the high-precision CNC double-end face grinder mentioned in step five is model AC1200F. Other steps and parameters are the same as in Specific Implementation Method One.

[0040] Specific Implementation Method Five: This implementation method differs from Specific Implementation Method One in that: in step five, the SUU130A equipment is used for grinding. The process parameters for the final grinding process are as follows: grinding wheel linear speed 20-35m / s, workpiece shaft speed 150-350r / min, feed rate 2~4μm / s. Other steps and parameters are the same as in Specific Implementation Method One.

[0041] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method One in that the runout tolerance of the outer circle of the positioning datum during the two positioning grinding operations in step six is ​​≤0.002mm, and the parallelism tolerance between plane A and plane B is ≤0.001mm. Other steps and parameters are the same as in Specific Implementation Method One.

[0042] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method One in that the fine grinding process in step seven uses diamond polishing paste, with a grinding pressure of 0.1-0.2 MPa and a grinding time of 15-20 min per groove. Other steps and parameters are the same as in Specific Implementation Method One.

[0043] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method One in that, in step seven, the surface roughness Ra of the channel is ensured to be ≤0.063μm. Other steps and parameters are the same as in Specific Implementation Method One.

[0044] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method One in that step eight uses a formula to help verify the actual channel spacing value. Other steps and parameters are the same as in Specific Implementation Method One.

[0045] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Method Nine in that the formula is: Ditch spacing = Width height - (Ditch position I + Ditch position II). Other steps and parameters are the same as in Specific Implementation Method Nine.

[0046] The beneficial effects of the present invention are verified using the following embodiments:

[0047] Example 1: The specific machining method for high-precision thin-walled double-row angular contact ball bearings is carried out according to the following steps:

[0048] 1. Turning: The bearing outer ring blank is turned to form the preliminary outer circle, plane A, plane B and inner circle structure;

[0049] II. Heat treatment: Heat treatment is performed on the machined workpiece;

[0050] III. Rough Grinding Cycle: Rough grinding is performed on the outer circle, plane A, and plane B of the workpiece.

[0051] IV. Supplementary Tempering: Supplementary tempering treatment is performed on the workpiece after rough grinding;

[0052] V. Final Grinding Cycle: Using a high-precision CNC double-end face grinder, process plane A and plane B according to the process of rough grinding plane → fine grinding plane → final grinding plane. Dress the grinding wheel before fine grinding and final grinding. After dressing, grind twice with a small feed rate. After the grinding wheel is stable, grind normally. Control the difference in width and height between products in the same batch to ≤0.003mm.

[0053] VI. Grinding the outer groove in sequence: First, using plane A and the outer circle as positioning references, grind the outer groove I, controlling the deviation of groove position I to be ≤0.01mm; then, using plane B and the outer circle as positioning references, grind the outer groove II.

[0054] VII. Fine grinding process: The fine grinding process is carried out in sequence as follows: rough grinding outer groove I → rough grinding outer groove II → fine grinding outer groove I → fine grinding outer groove II;

[0055] 8. Testing and Calibration: Use a profilometer to test the actual spacing of the channels and adjust the channel position;

[0056] 9. Post-processing: Demagnetize and clean the workpiece to complete the processing.

[0057] The processing uses a high-quality 89A180KV grinding wheel; the supplementary tempering temperature in step four is 250℃; the high-precision CNC double-end face grinder in step five is model AC1200F; in step five, a SUU130A machine is used for grinding, and the final grinding process parameters are as follows: grinding wheel linear speed 20-35m / s, workpiece shaft speed 150-350r / min, feed speed 2~4μm / s; in step six, the runout tolerance of the outer circle of the positioning datum in the two positioning grinding operations is ≤0.002mm, and the parallelism tolerance between plane A and plane B is ≤0.001mm; in step seven, the finishing process uses diamond grinding paste, grinding pressure 0.1-0.2MPa, and grinding time 15-20min / groove; in step seven, the surface roughness Ra of the groove is ensured to be ≤0.063μm; in step eight, the actual groove spacing value is verified by the formula: groove spacing = width height - (groove position I + groove position II).

[0058] The double groove position meets the 0.015mm requirement, eliminating grinding vibration marks on the groove surface, and all the product's precision requirements are met.

Claims

1. A method for machining a high-precision thin-walled double-row angular contact ball bearing, characterized in that... The specific machining method for high-precision thin-walled double-row angular contact ball bearings is as follows:

1. Turning: The bearing outer ring blank is turned to form the preliminary outer circle, plane A, plane B and inner circle structure; II. Heat treatment: Heat treatment is performed on the machined workpiece; III. Rough Grinding Cycle: Rough grinding is performed on the outer circle, plane A, and plane B of the workpiece. IV. Supplementary Tempering: Supplementary tempering treatment is performed on the workpiece after rough grinding; V. Final Grinding Cycle: Using a high-precision CNC double-end face grinder, process plane A and plane B according to the process of rough grinding plane → fine grinding plane → final grinding plane. Dress the grinding wheel before fine grinding and final grinding. After dressing, grind twice with a small feed rate. After the grinding wheel is stable, grind normally. Control the difference in width and height between products in the same batch to ≤0.003mm. VI. Grinding the outer groove in sequence: First, using plane A and the outer circle as positioning references, grind the outer groove I, controlling the deviation of groove position I to be ≤0.01mm; then, using plane B and the outer circle as positioning references, grind the outer groove II. VII. Fine grinding process: The fine grinding process is carried out in sequence as follows: rough grinding outer groove I → rough grinding outer groove II → fine grinding outer groove I → fine grinding outer groove II; 8. Testing and Calibration: Use a profilometer to test the actual spacing of the channels and adjust the channel position; 9. Post-processing: Demagnetize and clean the workpiece to complete the processing.

2. The machining method for a high-precision thin-walled double-row angular contact ball bearing according to claim 1, characterized in that... The machining process uses a high-quality 89A180KV grinding wheel.

3. The machining method for a high-precision thin-walled double-row angular contact ball bearing according to claim 1, characterized in that... The additional tempering temperature mentioned in step four is 250°C.

4. The machining method for a high-precision thin-walled double-row angular contact ball bearing according to claim 1, characterized in that... The high-precision CNC double-end face grinder mentioned in step five is model AC1200F.

5. The machining method for a high-precision thin-walled double-row angular contact ball bearing according to claim 1, characterized in that... In step five, the SUU130A equipment is selected for grinding. The process parameters for the final grinding process are as follows: grinding wheel linear speed 20-35m / s, workpiece shaft speed 150-350r / min, and feed rate 2~4μm / s.

6. The machining method for a high-precision thin-walled double-row angular contact ball bearing according to claim 1, characterized in that... In step six, the runout tolerance of the outer circle of the positioning datum during the two positioning grinding operations is ≤0.002mm, and the parallelism tolerance between plane A and plane B is ≤0.001mm.

7. The machining method for a high-precision thin-walled double-row angular contact ball bearing according to claim 1, characterized in that... In step seven, the fine grinding process uses diamond grinding paste, with a grinding pressure of 0.1-0.2 MPa and a grinding time of 15-20 min per groove.

8. The machining method for a high-precision thin-walled double-row angular contact ball bearing according to claim 1, characterized in that... In step seven, ensure that the surface roughness Ra of the channel is ≤0.063μm.

9. A method for machining a high-precision thin-walled double-row angular contact ball bearing according to claim 1, characterized in that... Step 8: Verify the actual channel spacing using formulas.

10. A method for machining a high-precision thin-walled double-row angular contact ball bearing according to claim 9, characterized in that... The formula is: Ditch spacing = Width height - (Ditch position I + Ditch position II).

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