Method and device for grinding the inner circle of a bearing ring with a large width-to-diameter ratio
By combining a three-stage grinding method with a positioning mechanism, the problems of low precision and flared mouth defects in the grinding process of bearing rings with large width-to-diameter ratios were solved, achieving efficient and precise inner circle machining of the rings and improving product qualification rate and dimensional consistency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- LUOYANG LYC BEARING
- Filing Date
- 2026-07-07
- Publication Date
- 2026-08-04
AI Technical Summary
Large width-to-diameter ratio bearing rings are easily affected by the cantilever length of the grinding wheel during the grinding process, resulting in lower machining accuracy, flared mouth defects, and low product qualification rate.
A three-stage grinding method is adopted, using short grinding wheel cantilever and long grinding wheel cantilever for segmented grinding. The short grinding wheel cantilever first enters the grinding from one end of the ring, and the grinding width is not less than half the width of the ring. After changing the direction, it enters from the other end. The long grinding wheel cantilever finally covers the full width. It is combined with electromagnetic chuck and positioning support for positioning to ensure that the positioning reference at both ends of the ring is consistent.
While ensuring processing efficiency, reduce flared mouth defects, improve product processing qualification rate, ensure the consistency and accuracy of the inner diameter of both ends of the ring, and enhance processing stability.
Smart Images
Figure CN122500573A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the technical field of apparatus for grinding the rotating surfaces of workpieces, and specifically to a method and apparatus for grinding the inner diameter of bearing rings with a large width-to-diameter ratio. Background Technology
[0002] High width-to-diameter ratio bearings (typically defined as bearings with a ring width B to an inner diameter d, where B / d ≥ 1) have become key components in high-end equipment such as aerospace engine spindles, precision CNC machine tools, and new energy vehicle drive motors due to their core characteristics including high axial stiffness, large load-bearing contact area, and excellent positioning accuracy. The inner circle of the bearing ring serves as the mating reference surface with the shaft, directly determining the bearing's assembly accuracy, rotational stability, and overall service life. Industry standards impose stringent requirements on its machining accuracy.
[0003] Precision bearing parts are machined by grinding. The basic structure of a conventional internal grinding machine can be found in a high-precision ball bearing internal grinding machine disclosed in Chinese utility model patent with authorization announcement number CN218533808U. The bearing is fixed by a corresponding clamping fixture, and the grinding wheel is mounted on the rotating shaft. The rotating shaft and the grinding wheel are driven to rotate by a servo motor, so that the grinding wheel grinds the inner circle of the bearing.
[0004] For bearing rings with a large width-to-diameter ratio, due to their "slender and thin-walled" structural characteristics, their torsional and bending rigidity is only 30% to 50% of that of conventional bearing rings. To accommodate their larger width and ensure that the grinding wheel can cover the entire inner circle, the grinding wheel needs a large overhang length. This allows the grinding wheel to be fixed at one end of the ring and then extend into the ring from the other end for grinding. During grinding, the grinding wheel abuts against the inner circle of the ring and has a set radial feed rate, bearing a certain radial force. The larger the overhang length of the grinding wheel, the greater the circular runout at the overhang end. This results in problems such as a long grinding wheel overhang, insufficient rigidity, and poor grinding stability during inner circle grinding. The grinding amount at the overhang end of the grinding wheel differs significantly from that at the other end. This large difference in grinding amount at both ends of the ring leads to a noticeable flared mouth defect after machining, meaning a large difference in the inner diameter at both ends of the ring, which does not meet the requirements and results in a low product qualification rate. Summary of the Invention
[0005] The purpose of this invention is to provide a method for grinding the inner diameter of bearing rings with a large width-to-diameter ratio, so as to solve the problem that the existing grinding methods are easily affected by the length of the grinding wheel overhang, resulting in low machining accuracy; the purpose of this invention is also to provide a device for grinding the inner diameter of bearing rings with a large width-to-diameter ratio, so as to solve the above problems.
[0006] The technical solution of the method for grinding the inner circle of bearing rings with a large width-to-diameter ratio according to the present invention is as follows: A method for grinding the inner diameter of a bearing ring with a large width-to-diameter ratio includes: defining the grinding wheel and the overhanging portion of the grinding wheel mounting shaft as a grinding wheel cantilever; configuring a long grinding wheel cantilever and a short grinding wheel cantilever, wherein the axial length of the short grinding wheel cantilever is less than the axial length of the long grinding wheel cantilever and less than the axial width of the ring; first, positioning end B of the ring, and using the short grinding wheel cantilever to enter the grinding from end A of the ring; then reversing the direction of the two ends of the ring, positioning end A of the ring, and using the short grinding wheel cantilever to enter the grinding from end B; then switching to the long grinding wheel cantilever to enter the grinding of the ring; the grinding width of the short grinding wheel cantilever is not less than half the width of the ring, and the grinding width of the long grinding wheel cantilever covers the width of the ring; the radial feed rate of the long grinding wheel cantilever during grinding is less than the radial feed rate of the short grinding wheel cantilever during grinding, and the grinding allowance of the long grinding wheel cantilever is less than the grinding allowance of the short grinding wheel cantilever.
[0007] Beneficial Effects: This invention pioneers a three-stage grinding method for the inner diameter grinding of bearing rings with large width-to-diameter ratios, reducing flared mouth defects while ensuring processing efficiency. The first stage involves positioning and fixing end B of the ring, then using a short grinding wheel cantilever to enter the grinding process from end A, with a grinding width not less than half the ring width. The second stage involves reversing the directions at both ends of the ring and positioning end A, then using a short grinding wheel cantilever to enter the grinding process from end B, with a grinding width not less than half the ring width. Finally, a long grinding wheel cantilever is used to enter the grinding process from end B, with a grinding width equal to the ring width. The short grinding wheel cantilever has a shorter overhang length. The overhanging end is less prone to large circular runout and belongs to the preliminary rough grinding stage, where the grinding speed can be relatively fast, achieving a high feed rate and bearing most of the grinding allowance, ensuring processing efficiency. The long grinding wheel overhang has a longer overhang length and belongs to the subsequent fine grinding stage. In this stage, the grinding speed is slow and the grinding amount is small, which can reduce the circular runout at the overhanging end and reduce the impact of the long overhang on the machining accuracy, ensuring the dimensional accuracy after final grinding. The cooperation of the three stages can ensure processing efficiency while not being easily affected by the length of the grinding wheel overhang, thus reducing the problem of flared mouth defects and improving the product processing qualification rate.
[0008] Furthermore, the grinding wheel length of the long grinding wheel cantilever is greater than that of the short grinding wheel cantilever, the grinding wheel length of the long grinding wheel cantilever is not less than the width of the collar, and the grinding wheel length of the short grinding wheel cantilever is less than the width of the collar but not less than half the width of the collar; the length of the overhanging portion of the grinding wheel mounting shaft is equal for both the long and short grinding wheel cantilever.
[0009] Beneficial effects: The grinding wheel width is not less than the required grinding width, and axial feed is not required during grinding, thus improving processing efficiency.
[0010] Furthermore, the electromagnetic chuck of the positioning mechanism adsorbs the end face of the ring for axial positioning, and the positioning support of the positioning mechanism cooperates with the outer circle of the ring to achieve radial positioning of the ring. The positioning support is axially positioned with the middle part of the outer circle of the ring.
[0011] Beneficial effects: The positioning references at both ends of the ring are the same, ensuring that the position of the ring remains unchanged after the direction of the ring is changed, ensuring the clamping accuracy of the ring and not affecting the machining accuracy.
[0012] Furthermore, the sum of the short grinding wheel cantilever grinding allowance and the long grinding wheel cantilever grinding allowance is the total allowance, with the short grinding wheel cantilever grinding allowance accounting for 60% to 75% of the total allowance; the radial feed rate during long grinding wheel cantilever grinding is 1 / 4 to 1 / 3 of the radial feed rate during short grinding wheel cantilever grinding.
[0013] Furthermore, the coolant used in grinding is an emulsion. The concentration of the emulsion used in long wheel cantilever grinding is greater than that used in short wheel cantilever grinding, and the flow rate of the emulsion in long wheel cantilever grinding is greater than that in short wheel cantilever grinding.
[0014] Furthermore, the grinding wheel grit number of the long grinding wheel cantilever is greater than that of the short grinding wheel cantilever; the grinding wheel hardness grade of the long grinding wheel cantilever is greater than that of the short grinding wheel cantilever.
[0015] Furthermore, half the width of the ferrule plus 2mm is less than the cantilever grinding width of the short grinding wheel.
[0016] Beneficial effect: It allows for a 2mm overlap in the two grinding widths of the short grinding wheel cantilever at both ends of the raceway, ensuring that the sum of the two grinding widths is not less than the overall axial width of the raceway, thus compatibility with errors.
[0017] The technical solution of the large width-to-diameter ratio bearing ring inner grinding device of the present invention is as follows: A grinding device for the inner diameter of a bearing ring with a large width-to-diameter ratio includes a positioning mechanism for positioning one end of the ring and positioning the other end after the two ends of the ring are reversed. It also includes a long grinding wheel cantilever and a short grinding wheel cantilever. The axial length of the short grinding wheel cantilever is less than the axial length of the long grinding wheel cantilever and is also less than the axial width of the ring. The short grinding wheel cantilever is used to enter the grinding process from the other end after positioning at one end of the ring. The long grinding wheel cantilever is used to grind the ring after the short grinding wheel cantilever has ground the ring. The grinding width of the short grinding wheel cantilever is not less than half the width of the ring, and the grinding width of the long grinding wheel cantilever covers the width of the ring. The radial feed rate of the long grinding wheel cantilever during grinding is less than that of the short grinding wheel cantilever, and the grinding allowance of the long grinding wheel cantilever is less than that of the short grinding wheel cantilever.
[0018] Beneficial effects: This invention provides a pioneering staged grinding device for the inner diameter grinding of bearing rings with large width-to-diameter ratios. This device reduces flared mouth defects while ensuring processing efficiency. The first stage involves positioning and fixing end B of the ring, then using a short grinding wheel cantilever to enter the grinding area from end A, with a grinding width not less than half the ring width. The second stage involves reversing the directions at both ends of the ring and positioning end A again, then using a short grinding wheel cantilever to enter the grinding area from end B, with a grinding width not less than half the ring width. Finally, a long grinding wheel cantilever is used to enter the grinding area from end B, with a grinding width equal to the ring width. The short grinding wheel cantilever has a shorter overhang length. The overhanging end is less prone to large circular runout and belongs to the preliminary rough grinding stage, where the grinding speed can be relatively fast, achieving a high feed rate and bearing most of the grinding allowance, ensuring processing efficiency. The long grinding wheel overhang has a longer overhang length and belongs to the subsequent fine grinding stage. In this stage, the grinding speed is slow and the grinding amount is small, which can reduce the circular runout at the overhanging end and reduce the impact of the long overhang on the machining accuracy, ensuring the dimensional accuracy after final grinding. The cooperation of the three stages can ensure processing efficiency while not being easily affected by the length of the grinding wheel overhang, thus reducing the problem of flared mouth defects and improving the product processing qualification rate.
[0019] Furthermore, both the long grinding wheel cantilever and the short grinding wheel cantilever include a grinding wheel and a grinding wheel mounting shaft cantilever portion. The grinding wheel is mounted on the grinding wheel mounting shaft cantilever portion. The grinding wheel length of the long grinding wheel cantilever is greater than that of the short grinding wheel cantilever. The grinding wheel length of the long grinding wheel cantilever is not less than the width of the collar, while the grinding wheel length of the short grinding wheel cantilever is less than the width of the collar but not less than half the width of the collar. The lengths of the grinding wheel mounting shaft cantilever portions of the long grinding wheel cantilever and the short grinding wheel cantilever are equal.
[0020] Beneficial effects: The grinding wheel width is not less than the required grinding width, and axial feed is not required during grinding, thus improving processing efficiency.
[0021] Furthermore, the positioning mechanism includes an electromagnetic chuck and a positioning support. The electromagnetic chuck of the positioning mechanism is used to adsorb the end face of the ring for axial positioning of the ring. The positioning support of the positioning mechanism is used to cooperate with the outer circle of the ring to achieve radial positioning of the ring. The positioning support is used to cooperate with the middle part of the outer circle of the ring for axial positioning.
[0022] Beneficial effects: The positioning references at both ends of the ring are the same, ensuring that the position of the ring remains unchanged after the direction of the ring is changed, ensuring the clamping accuracy of the ring and not affecting the machining accuracy. Attached Figure Description
[0023] Figure 1 This is a schematic diagram of the staged grinding process in an embodiment of the large width-to-diameter ratio bearing ring inner circle grinding method of the present invention.
[0024] In the diagram: 1. Grinding ring; 21. Short grinding wheel; 22. Long grinding wheel; 3. Grinding wheel mounting shaft; 4. Support base. Detailed Implementation
[0025] The basic concept of the bearing ring inner grinding method of the present invention is to first use a short grinding wheel to perform two segmented rough grindings from both ends of the ring, which has a fast grinding speed and removes most of the grinding allowance. Then, a long grinding wheel is used to perform full-section grinding, which has a small grinding allowance and is less affected by the circular runout at the end of the long cantilever. In this way, by using a short grinding wheel for large-allowance segmented rough grinding and a long grinding wheel for small-allowance full-section fine grinding, the defects of the flared mouth are reduced while meeting certain processing efficiency. The yield of the bearing ring has been improved in actual processing using this method.
[0026] The following is a detailed description with reference to specific embodiments.
[0027] An embodiment of the method for grinding the inner diameter of bearing rings with a large width-to-diameter ratio according to the present invention: The grinding method for the inner diameter of bearing rings with a large width-to-diameter ratio is implemented using a grinding device for the inner diameter of bearing rings with a large width-to-diameter ratio, such as... Figure 1 As shown, this method is used to grind the inner circle, i.e., the inner circumferential surface, of the collar 1, where the axial width of the collar 1 is greater than its inner diameter. The method includes: The system is equipped with a long grinding wheel cantilever and a short grinding wheel cantilever. The axial length of the short grinding wheel cantilever is L1, and the axial length of the long grinding wheel cantilever is L2. The short grinding wheel cantilever includes the portion of the short grinding wheel 21 and the grinding wheel mounting shaft 3 that extends out of the support seat 4, while the long grinding wheel cantilever includes the portion of the long grinding wheel 22 and the grinding wheel mounting shaft 3 that extends out of the support seat 4. The axial length of the short grinding wheel cantilever is less than the axial length of the long grinding wheel cantilever and less than the axial width of the collar 1; the two ends of the collar 1 are end A and end B, respectively; first, end B of the collar 1 is positioned, and the short grinding wheel cantilever is used to enter the inner hole of the collar 1 from end A to grind a section of its inner circle near end A; then the two ends of the collar 1 are reversed, end A of the collar 1 is positioned, and the short grinding wheel cantilever is used to enter the inner hole of the collar 1 from end B to grind a section of its inner circle near end B; then the long grinding wheel cantilever is used to enter the inner hole of the collar 1 from end B to grind the entire section of its inner circle; the grinding width of the short grinding wheel cantilever is not less than half the width of the collar 1, and the grinding width of the long grinding wheel cantilever covers the width of the collar 1, and the grinding width is the axial dimension of the part being ground in the corresponding stage; the radial feed rate of the long grinding wheel cantilever is less than the radial feed rate of the short grinding wheel cantilever, and the grinding allowance of the long grinding wheel cantilever is less than the grinding allowance of the short grinding wheel cantilever.
[0028] This grinding method is a three-stage grinding method, which can reduce the impact of flared mouth defects while ensuring processing efficiency. Combined with... Figure 1The diagram illustrates the three-stage grinding process. The first and second stages use a short grinding wheel cantilever, while the third stage uses a long grinding wheel cantilever. The axial length of the grinding wheel in the short grinding wheel cantilever is less than that in the long grinding wheel cantilever; that is, the length of the short grinding wheel 21 is less than the length of the long grinding wheel 22, while the grinding wheel diameters can be the same, and the grinding wheel diameter is less than the inner diameter of the collar 1. In the first stage, after fixing the B end of the collar 1, the short grinding wheel cantilever enters the grinding process from the A end of the collar 1, with a grinding width not less than half the width of the collar 1. In the second stage, after changing the direction at both ends of the collar 1 and fixing the A end of the collar 1, the short grinding wheel cantilever enters the grinding process from the B end of the collar 1, with a grinding width not less than half the width of the collar 1. Then, the long grinding wheel cantilever is used to enter the grinding process from the B end of the collar 1, with a grinding width equal to the width of the collar 1. The set grinding amount is achieved through the reciprocating axial movement of the grinding wheel.
[0029] Because the short grinding wheel cantilever has a shorter overhang length, it is less prone to large circular runout at the end of the overhang. Furthermore, it belongs to the rough grinding stage, allowing for a relatively high grinding speed and feed rate, and it handles most of the grinding allowance, ensuring processing efficiency. The long grinding wheel cantilever, with its longer overhang length, belongs to the subsequent finish grinding stage. This stage features a slower grinding speed and smaller grinding depth, reducing circular runout at the end of the overhang. The smaller grinding allowance also minimizes the impact of the long cantilever on machining accuracy, ensuring the final dimensional accuracy. By coordinating the long and short grinding wheels with the three grinding stages, overall processing efficiency can be maintained while minimizing the impact of grinding wheel cantilever length on machining accuracy, reducing flared mouth defects, and improving product yield.
[0030] The grinding wheel and the overhanging portion of the grinding wheel mounting shaft 3 are defined as a grinding wheel cantilever. The grinding wheel is used for internal grinding of the inner ring 1 of a bearing with a large width-to-diameter ratio. In this embodiment, the ring 1 is the inner ring of the bearing. The grinding wheel and the grinding wheel mounting shaft 3 are coaxially arranged, and the grinding wheel is fixedly mounted on the overhanging end of the grinding wheel mounting shaft 3. The grinding wheel mounting shaft 3 is connected to the corresponding drive mechanism of the grinding device. The worktable of the grinding device is provided with a support seat 4 to support the rotation of the grinding wheel mounting shaft 3. The overhanging portion of the grinding wheel mounting shaft 3 is the cantilevered portion that protrudes from the support seat 4 and is not supported. The overall overhanging length of the grinding wheel and the overhanging portion of the grinding wheel mounting shaft 3 relative to the support seat 4 after installation is the axial length of the grinding wheel cantilever. This length is related to the grinding width and determines the depth to which the grinding wheel can extend into the inner hole of the ring 1, that is, it is related to the axial width of the ring 1. The worktable of the grinding device is movable, and the drive mechanism is set on the worktable. When the worktable moves, the grinding wheel can move, and feed motion and retraction relative to the inner hole of the ring 1 can be realized. The drive mechanism can drive the grinding wheel to rotate via the grinding wheel mounting shaft 3 to grind the inner circle of the collar 1.
[0031] The grinding device positions the collar 1 using a positioning mechanism, providing axial and radial positioning. The positioning mechanism includes an electromagnetic chuck and a positioning support. The electromagnetic chuck is used to attract the end face of the collar 1 for axial positioning, while the positioning support engages with the outer circle of the collar 1 for radial positioning. The positioning support can be a V-shaped seat, with the collar 1 placed in the positioning groove of the V-shaped seat to ensure its radial position and counteract radial load. The positioning support can be located below the collar 1, and it is rotatable and movable, allowing it to reverse the direction of the collar 1 and change the orientation of its two ends. Positioning supports can be installed on both radial sides of the collar 1, clamping and positioning it, and using the degrees of freedom of the positioning supports to reverse the direction of the collar 1. The positioning support contacts but does not press against the outer circle of the collar 1, allowing the electromagnetic chuck to slowly rotate the collar 1. Since the outer circle of the collar 1 has not yet undergone finishing, the minor friction between the positioning support and the outer circle of the collar 1 does not affect subsequent processing.
[0032] The grinding wheel and the collar 1 are aligned on the same axis. The orientation of the grinding wheel relative to the collar 1 during grinding can be set according to requirements. The grinding device uses a precision machine tool or an ultra-precision CNC machine tool, and the workpiece positioning accuracy meets the requirements. The machining accuracy can reach the micron to sub-micron level. The operation of changing the direction of both ends of the collar 1 and changing the length of the grinding wheel can be automatically completed by the machine tool control program and the actuator. The long grinding wheel cantilever and the short grinding wheel cantilever can be installed on the same turntable of the machine tool. The turntable is used to form a support base 4. By rotating the turntable, different grinding wheels can be switched for processing, which can meet the requirements of grinding wheel movement.
[0033] In some application scenarios, the operation of changing the direction of both ends of the ring 1 and changing the length of the grinding wheel can also be done manually. Since the clamping and positioning reference is the same, the clamping accuracy can be guaranteed. Although the processing efficiency is affected to some extent, the grinding amount of the long grinding wheel cantilever can be greatly reduced. Therefore, in actual operation, the problem of the flared mouth defect is still improved and the yield is increased.
[0034] Furthermore, through the process design of symmetrical rough grinding with large allowance at both ends, the elastic deformation and thermal deformation generated by the processing of both ends A and B are symmetrically distributed and cancel each other out, effectively improving the bending and skew problems caused by unidirectional grinding of the ring 1. The small allowance for grinding throughout the entire section can reduce the deviation of the inner diameter of both ends A and B after processing, ensuring the consistency of the dimensions of both ends of the workpiece.
[0035] The grinding wheel length of the long grinding wheel cantilever is greater than that of the short grinding wheel cantilever. The grinding wheel length of the long grinding wheel cantilever is not less than the width of the collar 1, while the grinding wheel length of the short grinding wheel cantilever is less than the width of the collar 1 but not less than half the width of the collar 1. The overhanging lengths of the grinding wheel mounting shaft 3 are equal for both the long and short grinding wheel cantilever arms. The grinding wheel width is not less than the required grinding width, and axial feed is not required during grinding, thus improving processing efficiency. When grinding with the short grinding wheel 21, its axial length is sufficient to cover the corresponding grinding width, without axial movement.
[0036] The electromagnetic chuck of the positioning mechanism adsorbs the end face of the collar 1 for axial positioning. The positioning support of the positioning mechanism cooperates with the outer circle of the collar 1 to achieve radial positioning of the collar 1. The positioning support and the outer circle of the collar 1 are axially positioned at the middle. The positioning references at both ends of the collar 1 are the same, ensuring that the position of the collar 1 remains unchanged after the direction is changed, ensuring the clamping accuracy of the collar 1 and not affecting the machining accuracy.
[0037] Half the width of the collar 1 plus 2mm is less than the grinding width of the short grinding wheel cantilever, so that the two grinding widths of the short grinding wheel cantilever at both ends of the collar 1 have a 2mm overlap area, ensuring that the sum of the two grinding widths is not less than the overall axial width of the collar 1, and to accommodate errors.
[0038] The sum of the short-wheel cantilever grinding allowance and the long-wheel cantilever grinding allowance is the total allowance, which is the amount of grinding material to be removed radially. The short-wheel cantilever grinding allowance accounts for 60% to 75% of the total allowance, and the remainder is the long-wheel cantilever grinding allowance. The radial feed rate during long-wheel cantilever grinding is 1 / 4 to 1 / 3 of that during short-wheel cantilever grinding. The coolant used in the grinding process is an emulsion. The emulsion concentration used in long-wheel cantilever grinding is higher than that used in short-wheel cantilever grinding, and the emulsion flow rate is also higher. The wheel grit size of the long-wheel cantilever grinding is greater than that of the short-wheel cantilever grinding. The wheel hardness grade of the long-wheel cantilever grinding is greater than that of the short-wheel cantilever grinding.
[0039] The specific steps are as follows: Phase 1: A-end directional grinding; An electromagnetic chuck is used to adhere to the B-end face of the collar 1, using the B-end face as the axial positioning reference. Simultaneously, a central positioning support supports the axial center outer circle of the collar 1, offsetting the radial grinding load and improving the overall rigidity of the machining system. In this stage, a short CBN grinding wheel 21 with ceramic bond is selected. The wheel grit size is #80~#100, the hardness grade is H~J, the outer diameter is smaller than the inner diameter of the collar 1, and the effective grinding width is greater than half the width of the collar 1 plus 2mm. The structure of the short grinding wheel 21 effectively shortens the grinding cantilever, structurally suppressing grinding chatter. The machining parameters are set as follows: grinding wheel linear speed 25-35 m / s, grinding wheel linear speed to workpiece linear speed ratio K controlled at 60-90. Grinding width is 1 / 2 width of ring 1 plus 2 mm, total machining allowance 0.15-0.3 mm, removing 60%-75% of the total allowance at end A; table feed speed is controlled at 0.003-0.006 mm / s, i.e. radial feed speed, using 5%-8% emulsion with a flow rate ≥10 L / min for cooling, to complete the stable rough machining of the large allowance at end A of ring 1.
[0040] Second stage: Reverse grinding at end B; After rough grinding of end A, rotate the collar 1 axially 180° and fix it to the same electromagnetic chuck with end A as the axial positioning reference. Keep the original outer circle positioning reference and support position of the collar 1 unchanged, so that the rotation center of the two clamping is coincident and the clamping radial runout is ≤0.003mm, ensuring the consistency of the machining reference. In this stage, the same short grinding wheel 21 of the same specifications as the rough grinding at end A is used to maintain consistent processing parameters. The ratio K of the grinding wheel linear speed to the workpiece linear speed is stably controlled between 60 and 90, and 60% to 75% of the total allowance at end B is removed. Through the process design of symmetrical grinding at both ends, the elastic deformation and thermal deformation generated at ends A and B are symmetrically distributed and cancel each other out, effectively improving the bending and skew problems caused by unidirectional grinding of the ring 1. After processing, the inner diameter deviation at ends A and B is ≤0.005mm, ensuring the consistency of the workpiece dimensions at both ends.
[0041] Third stage: Full internal circular oscillating grinding: While maintaining the current workpiece clamping state, replace the short grinding wheel 21 with a ceramic bonded CBN long grinding wheel 22. The long grinding wheel 22 has a grit size of #100 to #120 and a hardness grade of J to K. The effective working length of the grinding wheel is greater than or equal to the overall width of the collar 1, which can completely cover the entire inner diameter area of the collar 1 and completely eliminate the connecting steps caused by segmented rough grinding. The machining parameters were set as follows: grinding wheel linear speed 28–32 m / s, and the ratio K of grinding wheel linear speed to workpiece linear speed of ring 1 was controlled within the range of 70–100. The axial oscillation speed of the grinding wheel was set to 0.2–0.3 mm / s to achieve uniform grinding across the entire width; the radial feed speed of the worktable was adjusted to 1 / 4–1 / 3 of that in the rough grinding stage, controlled within the range of 0.001–0.002 mm / s. In this stage, 25%–40% of the total allowable material was removed, and this was only used to correct dimensional and shape errors from previous machining processes. Simultaneously, a 6%–10% concentration emulsion with a flow rate ≥15 L / min was used to enhance cooling, preventing thermal deformation and surface burns on the workpiece. Ultimately, the inner diameter deviation at both ends A and B of ring 1 was guaranteed to be ≤0.003 mm, and the batch processing pass rate was ≥80%.
[0042] The following example illustrates this using a specific workpiece, ring 1: Example 1: Ring 1 has a width-to-diameter ratio B / d=2.33, an axial width of 14mm, an inner diameter of 6mm, and a total machining allowance of 0.2mm; In the rough grinding stage, a ceramic-bonded CBN short grinding wheel 21 with #100 grit, J-grade hardness, and specifications of φ4mm×10mm×1.5mm was selected. The grinding wheel linear speed was 10m / s, the ratio of grinding wheel linear speed to workpiece linear speed was K=64, the feed speed was 0.003mm / s, and the rough grinding allowance was 0.15mm. Symmetrical rough grinding of both ends A and B of the ring 1 was completed, with a dimensional deviation of 0.003mm at both ends. During the fine grinding stage, replace the #120 grit, K-grade hardness, φ4mm×15mm×1.5mm ceramic bond CBN long grinding wheel 22. The grinding wheel linear speed is 12m / s, the ratio of grinding wheel linear speed to workpiece linear speed is K=73, the oscillation speed is 0.2mm / s, the feed speed is 0.001mm / s, and the fine grinding allowance is 0.05mm. After processing, the inner diameter difference between the two ends of the collar 1 is 0.0025mm, the batch processing qualification rate is 86%, and there are no flared mouths, no segmented steps, and no surface burn defects.
[0043] Example 2: Ring 1 has a width-to-diameter ratio B / d=2.25, an axial width of 18mm, an inner diameter of 8mm, and a total machining allowance of 0.25mm; In the rough grinding stage, a ceramic-bonded CBN short grinding wheel 21 with #80 grit, H-grade hardness, and specifications of φ6mm×12mm×2mm is selected. The grinding wheel linear speed is 16m / s, the ratio of grinding wheel linear speed to workpiece linear speed is K=70, and the feed speed is 0.006mm / s. Symmetrical rough grinding is completed at both ends, with a dimensional deviation of 0.004mm at both ends. During the fine grinding stage, replace the #150 grit, K-grade hardness, φ6mm×19mm×2mm ceramic bond CBN long grinding wheel 22. The grinding wheel linear speed is 18m / s, the ratio of grinding wheel linear speed to workpiece linear speed is K=80, the oscillation speed is 0.3mm / s, the feed speed is 0.002mm / s, and the fine grinding allowance is 0.08mm. After processing, the difference in inner diameter between the two ends of the collar 1 is 0.003mm, the batch processing qualification rate is 88%, and the processing accuracy is uniform and stable.
[0044] Example 3: Ring 1 has a width-to-diameter ratio B / d=1.8, an axial width of 20mm, an inner diameter of 11mm, and a total machining allowance of 0.3mm; In the rough grinding stage, a ceramic-bonded CBN short grinding wheel 21 with #100 grit, H-grade hardness, and specifications of φ9mm×13mm×4mm is selected. The grinding wheel linear speed is 21m / s, the ratio of grinding wheel linear speed to workpiece linear speed is K=90, and the feed speed is 0.008mm / s. The rough grinding of the two ends of the ring 1A and B is completed symmetrically in sections. The deviation of the inner diameter of the two ends is controlled within 0.0035mm, and the excess material at both ends is removed evenly. During the fine grinding stage, replace the grinding wheel with a CBN long grinding wheel 22 with a #120 grit size, J grade hardness, and a specification of φ9mm×21mm×4mm. The grinding wheel linear speed is 25m / s, the ratio of grinding wheel linear speed to workpiece linear speed is K=100, the oscillation speed is 0.25mm / s, the feed speed is 0.002mm / s, and the fine grinding allowance is 0.12mm. After processing, the difference in inner diameter between the two ends of the collar 1 is stable at 0.0028mm, the batch processing qualification rate is 83%, which meets the accuracy requirements. The inner circle has no steps, no taper, and no surface burns, and the dimensional consistency is excellent, making it suitable for mass production conditions.
[0045] Compared to the industry-standard one-time full-length grinding process, the processing results show that the inner diameter deviation at both ends of the workpiece is ≥0.008mm, there is an obvious flared mouth defect, the batch processing qualification rate is only 55%, and the processing accuracy and stability are far lower than the process of this invention.
[0046] A three-stage grinding process is adopted to achieve phased control of "rough grinding to remove excess material and fine grinding to maintain accuracy". The first two stages remove excess material at both ends and correct coaxiality. The third stage is oscillating grinding to eliminate local defects, which fundamentally solves the horn-shaped problem caused by single grinding and keeps the average inner diameter variation within the range required by the product drawing.
[0047] By optimizing the allowance distribution ratio and combining it with the precision machining characteristics of oscillating grinding, the stability and geometric accuracy of the inner diameter are effectively improved, increasing the machining pass rate from less than 60% to over 80%. It is less susceptible to manufacturing and assembly errors. During full-section precision grinding, the allowance is already very small, making it less affected by long cantilever sections. This solves the problems of significant chatter, large thin-wall deformation, easy formation of steps in sections, low machining accuracy, and poor batch pass rate in the existing grinding process of thin-walled bearing rings with large width-to-diameter ratios. It achieves high-precision, high-stability, and high-pass-rate batch machining of thin-walled bearing ring inner diameters. It can effectively control deformation, improve product machining accuracy and consistency, meet the needs of high-end equipment, and has significant engineering application value and industry significance.
[0048] Embodiments of the large width-to-diameter ratio bearing ring inner grinding device of the present invention: The internal grinding device for the high aspect ratio bearing ring in this embodiment is the same as the grinding device described in the above embodiments. The internal grinding device for the high aspect ratio bearing ring includes a positioning mechanism for positioning one end of the ring and positioning the other end after the two ends of the ring are reversed. It also includes a long grinding wheel cantilever and a short grinding wheel cantilever. The axial length of the short grinding wheel cantilever is less than the axial length of the long grinding wheel cantilever and is less than the axial width of the ring. The short grinding wheel cantilever is used to enter the grinding process from the other end after positioning one end of the ring. The long grinding wheel cantilever is used to grind the ring after the short grinding wheel cantilever has ground it. The grinding width of the short grinding wheel cantilever is not less than half the width of the ring, and the grinding width of the long grinding wheel cantilever covers the width of the ring. The radial feed rate of the long grinding wheel cantilever during grinding is less than the radial feed rate of the short grinding wheel cantilever during grinding, and the grinding allowance of the long grinding wheel cantilever is less than the grinding allowance of the short grinding wheel cantilever.
[0049] The first stage involves positioning and fixing end B of the ring, then using a short grinding wheel cantilever to enter the grinding area from end A, with a grinding width no less than half the ring width. The second stage involves reversing the directions at both ends of the ring and positioning end A, then using a short grinding wheel cantilever to enter the grinding area from end B, with a grinding width no less than half the ring width. Then, a long grinding wheel cantilever is used to enter the grinding area from end B, with a grinding width equal to the ring width. The short grinding wheel cantilever has a shorter overhang, making it less prone to large circular runout at the end, and it belongs to the preliminary rough grinding stage. The cutting speed can be relatively fast, achieving a high feed rate and handling most of the grinding allowance, ensuring processing efficiency. The long grinding wheel cantilever has a relatively long overhang length and belongs to the subsequent fine grinding stage. In this stage, the grinding speed is slow and the grinding amount is small, which can reduce the circular runout at the end of the overhang and reduce the impact of the long cantilever on the machining accuracy, ensuring the dimensional accuracy after final grinding. The three stages work together to ensure processing efficiency while not being easily affected by the length of the grinding wheel cantilever, thus reducing the problem of flared mouth defects and improving the product processing qualification rate.
[0050] Both long and short grinding wheel cantilever arms include a grinding wheel and a cantilevered portion of the grinding wheel mounting shaft. The grinding wheel is mounted on this cantilevered portion. The grinding wheel length of the long grinding wheel cantilever arm is greater than that of the short grinding wheel cantilever arm, and the grinding wheel length of the long grinding wheel cantilever arm is not less than the width of the grinding ring. The grinding wheel length of the short grinding wheel cantilever arm is less than the width of the grinding ring but not less than half the width of the grinding ring. The lengths of the cantilevered portions of the grinding wheel mounting shaft are equal in both long and short grinding wheel cantilever arms. The grinding wheel width is not less than the required grinding width, allowing for the elimination of axial feed during grinding, thus improving processing efficiency.
[0051] The positioning mechanism includes an electromagnetic chuck and a positioning support. The electromagnetic chuck is used to adsorb the end face of the race ring for axial positioning. The positioning support engages with the outer circle of the race ring to achieve radial positioning. The positioning support also engages with the center of the outer circle of the race ring for axial positioning. The positioning references at both ends of the race ring are the same, ensuring that the position remains unchanged after the race ring is reversed, guaranteeing the clamping accuracy of the race ring and not affecting the machining accuracy.
[0052] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still make modifications to the technical solutions described in the foregoing embodiments without creative effort, or make equivalent substitutions for some of the technical features. 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.
Claims
1. A method for grinding the inner diameter of bearing rings with a large width-to-diameter ratio, characterized in that, the following is defined: The grinding wheel and the grinding wheel mounting shaft cantilever are configured as a whole as a grinding wheel cantilever, with a long grinding wheel cantilever and a short grinding wheel cantilever. The axial length of the short grinding wheel cantilever is less than the axial length of the long grinding wheel cantilever and less than the axial width of the raceway. First, position end B of the raceway and use the short grinding wheel cantilever to enter the grinding from end A of the raceway. Then, reverse the direction of the two ends of the raceway, position end A of the raceway, and use the short grinding wheel cantilever to enter the grinding from end B. Then, switch to the long grinding wheel cantilever to enter the grinding of the raceway. The grinding width of the short grinding wheel cantilever is not less than half the width of the raceway, and the grinding width of the long grinding wheel cantilever covers the width of the raceway. The radial feed rate of the long grinding wheel cantilever is less than that of the short grinding wheel cantilever, and the grinding allowance of the long grinding wheel cantilever is less than that of the short grinding wheel cantilever.
2. The method for grinding the inner diameter of bearing rings with a large width-to-diameter ratio according to claim 1, characterized in that, The grinding wheel length of the long grinding wheel cantilever is greater than that of the short grinding wheel cantilever. The grinding wheel length of the long grinding wheel cantilever is not less than the width of the collar, while the grinding wheel length of the short grinding wheel cantilever is less than the width of the collar but not less than half the width of the collar. The lengths of the overhanging portions of the grinding wheel mounting shafts of both the long and short grinding wheel cantilever are equal.
3. The method for grinding the inner diameter of bearing rings with a large width-to-diameter ratio according to claim 1 or 2, characterized in that, The electromagnetic chuck of the positioning mechanism adsorbs the end face of the ferrule for axial positioning. The positioning support of the positioning mechanism cooperates with the outer circle of the ferrule to achieve radial positioning of the ferrule. The positioning support is axially positioned with the middle part of the outer circle of the ferrule.
4. The method for grinding the inner diameter of bearing rings with a large width-to-diameter ratio according to claim 1 or 2, characterized in that, The total allowance is the sum of the short wheel cantilever grinding allowance and the long wheel cantilever grinding allowance. The short wheel cantilever grinding allowance accounts for 60% to 75% of the total allowance. When grinding with a long wheel cantilever, the radial feed rate is 1 / 4 to 1 / 3 of that when grinding with a short wheel cantilever.
5. The method for grinding the inner diameter of bearing rings with a large width-to-diameter ratio according to claim 1 or 2, characterized in that, The coolant used in grinding is an emulsion. The concentration of the emulsion used in long wheel cantilever grinding is greater than that used in short wheel cantilever grinding, and the flow rate of the emulsion in long wheel cantilever grinding is greater than that in short wheel cantilever grinding.
6. The method for grinding the inner diameter of bearing rings with a large width-to-diameter ratio according to claim 1 or 2, characterized in that, The grinding wheel grit size of a long grinding wheel cantilever is greater than that of a short grinding wheel cantilever; the grinding wheel hardness grade of a long grinding wheel cantilever is greater than that of a short grinding wheel cantilever.
7. The method for grinding the inner diameter of bearing rings with a large width-to-diameter ratio according to claim 1 or 2, characterized in that, Half the width of the ring plus 2mm is less than the cantilever grinding width of the short grinding wheel.
8. A grinding device for the inner diameter of bearing rings with a large width-to-diameter ratio, characterized in that, The device includes a positioning mechanism for positioning one end of the race ring and for positioning the other end after the two ends of the race ring are reversed. It also includes a long grinding wheel cantilever and a short grinding wheel cantilever. The axial length of the short grinding wheel cantilever is less than the axial length of the long grinding wheel cantilever and is less than the axial width of the race ring. The short grinding wheel cantilever is used to enter the grinding process from the other end after positioning one end of the race ring. The long grinding wheel cantilever is used to grind the race ring after the short grinding wheel cantilever has ground the race ring. The grinding width of the short grinding wheel cantilever is not less than half the width of the race ring, and the grinding width of the long grinding wheel cantilever is sufficient to cover the width of the race ring. The radial feed rate of the long grinding wheel cantilever during grinding is less than the radial feed rate of the short grinding wheel cantilever during grinding, and the grinding allowance of the long grinding wheel cantilever is less than the grinding allowance of the short grinding wheel cantilever.
9. The grinding device for the inner diameter of bearing rings with a large width-to-diameter ratio according to claim 8, characterized in that, Both the long grinding wheel cantilever and the short grinding wheel cantilever include a grinding wheel and a grinding wheel mounting shaft cantilever. The grinding wheel is mounted on the grinding wheel mounting shaft cantilever. The grinding wheel length of the long grinding wheel cantilever is greater than that of the short grinding wheel cantilever. The grinding wheel length of the long grinding wheel cantilever is not less than the width of the raceway. The grinding wheel length of the short grinding wheel cantilever is less than the width of the raceway but not less than half the width of the raceway. The lengths of the grinding wheel mounting shaft cantilever are equal for both the long and short grinding wheel cantilever.
10. The grinding apparatus for the inner diameter of bearing rings with a large width-to-diameter ratio according to claim 8 or 9, characterized in that, The positioning mechanism includes an electromagnetic chuck and a positioning support. The electromagnetic chuck of the positioning mechanism is used to adsorb the end face of the ring for axial positioning of the ring. The positioning support of the positioning mechanism is used to cooperate with the outer circle of the ring to achieve radial positioning of the ring. The positioning support is used to cooperate with the middle part of the outer circle of the ring for axial positioning.