Motor shaft double-groove indexing machining method for high coaxiality requirement

Abstract

The application relates to the technical field of precision machining of motor shafts, and discloses a double-groove indexing machining method for a motor shaft with high coaxiality requirements, which is used for solving the problems of unstable rotor positioning, uneven force on the connecting piece, increased operation noise and increased heating in the traditional method; the method firstly obtains the radial runout state of each shaft section of the segmented motor shaft, establishes a unified reference axis penetrating through the motor shaft, and takes the unified reference axis as a machining reference to sequentially perform axial positioning, circumferential reference position calibration, first-groove compensation machining, second-groove correction indexing machining and double-groove final inspection and finishing; the application can improve the angular position consistency of the double grooves, the position consistency of the groove center planes and the operation stability after the motor shaft is assembled.

Description

Technical Field

[0001] This invention relates to the field of precision machining technology for motor shafts, specifically a double-groove indexing machining method for motor shafts with high coaxiality requirements. Background Technology

[0002] Segmented motor shafts are typically formed by connecting a front shaft, an intermediate mating section, and a rear shaft. Double grooves are machined at the shaft extension end, the core mating section, or the connecting section to meet the requirements of torque transmission, rotor positioning, and assembly phase control. In the prior art, CN104439456B discloses a method for machining double keyways distributed at 180° on the shaft extension end of a large motor, which ensures the circumferential symmetry of the two keyways through the same adjusting tooling plane. CN115070436B discloses a machining method suitable for motor rotor shafts, which completes the machining of the outer diameter and positioning keyways using a milling and turning composite equipment and two center drives.

[0003] The above-mentioned solutions can improve the keyway machining accuracy of integral motor shafts or rotor shafts to a certain extent. However, for segmented motor shafts, the front section, intermediate mating section, and rear section are prone to axial misalignment during rough turning, finish turning, heat treatment, assembly, and secondary clamping. Moreover, double-slot machining requires angular indexing. Existing machining methods mostly use a single shaft diameter, V-shaped support, or local alignment datum as positioning references, which cannot simultaneously reflect the actual coaxiality of each shaft segment and the angular positional relationship between the double slots. This results in the double slots meeting the positional requirements under the machining datum, but the center plane of the slot bottom may still be offset relative to the actual rotation axis in the assembly state. This leads to unstable rotor positioning, uneven stress on connecting parts, increased operating noise, and increased heat generation. Therefore, it is urgent to propose a double-slot indexing machining method for motor shafts with high coaxiality requirements. This method should establish a unified axial datum for segmented motor shafts and identify and compensate for coaxiality and angular indexing errors during double-slot indexing machining, thereby improving the consistency of double slot positions and the assembly and operation stability of the motor shaft. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a double-groove indexing machining method for motor shafts with high coaxiality requirements, thus solving the problems mentioned in the background section.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A double-groove indexing machining method for motor shafts with high coaxiality requirements includes: S1, obtain the radial runout states of the front section, middle mating section and rear section of the segmented motor shaft respectively, and determine the unified reference axis through the motor shaft based on the alignment state of each shaft segment; S2, using a unified reference axis as the machining reference, performs axial positioning and circumferential reference position calibration of the motor shaft, and establishes the angular correspondence between the double groove to be machined and the circumferential reference position; S3, adjust the machining position of the first groove according to the offset state of each shaft segment relative to the unified reference axis, and perform milling machining on the first groove; S4, detect the offset of the center plane of the first groove relative to the unified reference axis, and correct the angular indexing reference of the second groove according to the detection result; S5, drive the motor shaft to rotate according to the corrected angular indexing reference, and perform milling on the second groove; S6 detects the position status of the first and second slots relative to the unified reference axis, and compensates and corrects the slot deviation based on the detection results.

[0007] Preferably, S1 includes: When obtaining the radial runout state, the motor shaft is mounted on a two-center support structure or a clamp-and-center support structure, and the motor shaft is driven to rotate at low speed. Multiple detection sections are arranged along the axial direction of each shaft segment, and circumferential equal-angle sampling is performed at each detection section; The sampled data underwent outlier retesting and validity verification. The unified reference axis is determined based on the equivalent rotation center and functional weight of each test section.

[0008] Preferably, S2 includes: When axial positioning and circumferential reference calibration, read the double groove process data table, and use a trigger probe to repeatedly test the bearing mounting end face, step end face or process end face to stabilize the trigger position as the axial zero point. Determine the circumferential reference position based on the angular reference of the drawing, assembly marks, or the predetermined feed direction of the first groove, and read the circumferential angle using the same-direction approximation method. Use the circumferential reference position as the starting point to determine the angular position of the first groove and the initial angle of the second groove.

[0009] Preferably, S3 includes: During the first slot milling process, the axial positioning record, circumferential reference position record, and double slot process data table are called.

[0010] Determine the radial compensation amount, lateral compensation amount, and segmented compensation nodes based on the location of the shaft segment and span of the first groove;

[0011] Select the milling tool, layer cutting depth, and feed parameters according to the width of the first slot and the material condition of the motor shaft;

[0012] Monitor spindle load, vibration status, and cutting noise during machining.

[0013] Preferably, S4 includes:

[0014] After the first groove is processed, a detection section is set along the length of the first groove while keeping it clamped.

[0015] Collect position data of the left tank wall, right tank wall and tank bottom, and determine the offset of the tank center plane based on the fitted position of the left tank wall and right tank wall;

[0016] The offset of the center plane of the groove is converted into an angular deviation value according to the radius of the groove;

[0017] The second groove's overall angular compensation data or segmented angular compensation data are generated based on the angular deviation direction of each detection section.

[0018] Preferably, S5 includes:

[0019] During the machining of the second groove, the target angle of the second groove is determined based on the correction data of the second groove. The motor shaft is driven to rotate in the same direction and the angle is locked and checked.

[0020] The overall compensation path is generated based on the angular deviation value represented by the first groove, or the segmented compensation path is generated based on the angular gradient compensation data, and rough milling, semi-finish milling and finish milling are performed in sequence, while monitoring angular drift, spindle load and vibration status.

[0021] Preferably, S6 includes:

[0022] After the double-groove machining is completed, the first groove detection record is called and the second groove detection record is generated under the current clamping state. The angular angle, groove center plane offset, groove width difference and groove depth difference of the first and second grooves are compared according to the same axial coordinate. The trimming path is formed according to the groove level and deviation type, and trimming is performed in the order of angular deviation, lateral deviation and depth deviation.

[0023] Compared with the prior art, the present invention provides a double-groove indexing machining method for motor shafts with high coaxiality requirements, which has the following advantages: 1. This invention, by collecting radial runout data from the front, middle, and rear sections of a segmented motor shaft, and establishing a unified reference axis running through the entire shaft based on the equivalent rotation center of each section, reduces the dependence of double-groove machining on a single shaft diameter, local alignment reference, or nominal outer circle center. Simultaneously, under the unified reference axis, axial positioning, circumferential reference calibration, first groove compensation machining, first groove center plane verification, second groove angular indexing correction, and final inspection and finishing of both grooves are completed. This ensures that coaxiality error, angular indexing error, and groove position deviation are continuously transmitted and corrected within the same machining session, avoiding the problem of positional deviation between the two grooves and the actual rotation axis caused by multiple clamping, cross-section axis offset, or indexing errors in the segmented motor shaft. This improves the consistency of the angular position of the two grooves, the consistency between the groove center plane and the actual rotation axis, and the operational stability of the motor shaft after assembly. 2. This invention, by writing radial runout data, axial positioning records, circumferential reference position records, first groove inspection records, second groove process data, and double groove final inspection data into the same machining session, enables the establishment of references, tool compensation, indexing verification, anomaly judgment, and compensation adjustment in double groove indexing machining to form a continuous machining data chain. For angular drift, groove width deviation, groove depth deviation, tool wear, or changes in clamping state that occur during machining, the source of deviation can be distinguished based on the machining data, and corresponding re-alignment, local adjustment, or termination of machining can be selected. This avoids blind rework based solely on the final inspection dimensions, thereby improving the process controllability, anomaly handling accuracy, and quality traceability of segmented motor shaft double groove machining. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the process for the double-groove indexing machining method of motor shafts with high coaxiality requirements according to the present invention. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some 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.

[0026] Example 1: Figure 1 A method for double-groove indexing machining of motor shafts with high coaxiality requirements is presented, including:

[0027] S1, obtain the radial runout states of the front section, middle mating section, and rear section of the segmented motor shaft respectively, and determine the unified reference axis through the motor shaft based on the alignment state of each shaft segment. The specific implementation is as follows:

[0028] Before performing double-groove indexing machining on the segmented motor shaft, the motor shaft is installed in a two-center support structure or a clamp-and-center support structure, enabling the motor shaft to rotate at low speed around the current support center. A machining session number for the current motor shaft is established, and information such as part number, material grade, heat treatment status, total axial length, diameter of the front section shaft, diameter of the intermediate mating section, diameter of the rear section shaft, shaft section where the double groove is located, design coaxiality tolerance, and design pitch angle are written in, serving as the data basis for subsequent alignment, calibration, machining, and verification.

[0029] For motor shafts made of 40Cr, 42CrMo, or 20CrMnTi materials, the alignment speed is between 5 r / min and 20 r / min. When the total axial length is less than 300 mm, the alignment speed can be selected from 10 r / min to 15 r / min. When the total axial length is not less than 300 mm, the alignment speed can be selected from 5 r / min to 10 r / min. 300 mm serves as the process boundary for the alignment stability of short and long shafts, mainly considering that longer motor shafts are more prone to support deflection and slight swaying during low-speed rotation measurement. The above speed range can reduce centrifugal sway and sensor following error, and meet the requirements for stable acquisition of radial runout data.

[0030] Multiple detection sections are set along the motor shaft axis, covering the front section, intermediate mating section, and rear section of the shaft. At least two detection sections are set for the front section, at least one for the intermediate mating section, and at least two for the rear section. When the front or rear section of the shaft has a bearing mounting section, the detection sections are preferentially placed near the bearing mounting section. When the intermediate mating section has steps, press-fit surfaces, or spline connection areas, the detection sections are preferentially placed in that mating area and its adjacent transition area. When the total axial length of the motor shaft is greater than 500mm, the number of detection sections is 7 to 11, and the spacing between adjacent detection sections is 50mm to 120mm. Segmented motor shafts longer than 500mm are more prone to mid-section deflection and cross-section axial offset when supported at both ends; increasing the number of detection sections can reflect changes in the axial direction. A spacing of 50mm to 120mm can cover common shaft segment steps and connection areas, avoiding situations where excessive spacing leads to undetected local offsets, and also avoiding excessively long measurement times due to insufficient spacing.

[0031] Radial runout data is collected at equal angles along the circumference of each detection section, with the number of sampling points ranging from 12 to 36, preferably 24. 12-point sampling meets the basic runout recognition requirements in the circumferential direction, while 36 points or more offer limited improvement in axis determination accuracy and increase sampling time. 24-point sampling corresponds to data collection every 15° in the circumferential direction, balancing circumferential coverage integrity and processing preparation efficiency. Radial runout data can be collected using contact probes, lever gauges, laser displacement sensors, or inductive micrometers, with a detection resolution of no less than 0.001 mm. When the shaft surface roughness Ra is greater than 1.6 μm, contact probes or lever gauges are preferred for detection. When the shaft surface has been precision ground and surface scratches need to be avoided, laser displacement sensors or inductive micrometers are preferred for detection.

[0032] Each detection section forms a radial runout record, which includes at least the following fields: machining session number, section number, axial coordinate, nominal diameter, circumferential angle sequence, radial displacement sequence, maximum runout value, minimum runout value, peak runout angle, data validity marker, and retest marker. The radial displacement sequence of the same detection section is validated. If the difference between a single sampling point and the mean of two adjacent sampling points exceeds 0.015 mm, and adjacent sampling points do not show continuous changes in the same direction, then the sampling point is marked as an isolated anomaly, and the corresponding circumferential angle is retested. 0.015 mm is more than 10 times the detection resolution of 0.001 mm, which can avoid sensor resolution noise, and is also below the control limit of residual deviation of the reference axis in high coaxiality double-groove machining. It is suitable for distinguishing between local anomalies caused by burrs, oil stains, or instantaneous sensor jitter and true axis offset.

[0033] If the number of invalid sampling points in the same detection section exceeds 10% of the total number of sampling points, the data of that detection section will be suspended from participating in the determination of the unified reference axis, and the data of that detection section will be re-acquired after cleaning the detection surface; the 10% ratio is used to judge whether the detection section data is still representative; when the invalid points exceed this ratio, it means that the surface condition or sampling stability of the section is not sufficient to support the determination of the section center, and continued use will cause the subsequent reference axis to deviate from the true rotation state;

[0034] After the validity verification of each detection section is completed, the equivalent rotation center point of the detection section is determined based on the circumferential angle sequence and radial displacement sequence within the same detection section. Specifically, the radial displacement corresponding to each circumferential angle is converted into a radial offset point relative to the nominal center, and the center position of the section that minimizes the overall radial deviation of each sampling point of the detection section is determined as the equivalent rotation center point of the detection section. Through this process, the radial runout data of a single detection section can be converted into spatial center data for determining the axis.

[0035] The equivalent rotation center points of each detection section are arranged according to the axial coordinate, and the segment weights are set in combination with the function of the shaft segment. The weight of the bearing mounting section is 1.0, the weight of the intermediate mating section is 0.7 to 0.9, and the weight of the non-mating outer circle or temporary clamping outer circle is 0.4 to 0.6. For example, the weights of the bearing mounting section, the intermediate mating section and the non-mating outer circle can be 1.0, 0.8 and 0.5 respectively. The above weight settings mainly consider that the bearing mounting section directly affects the rotation reference after the motor shaft is assembled, the intermediate mating section affects the assembly position of the rotor or connecting parts, and the non-mating outer circle has a relatively small impact on the actual running axis.

[0036] Based on the equivalent rotation center point, axial coordinates, and segment weights of each detection section, a unified reference axis is determined that runs through the front section, the intermediate mating section, and the rear section of the shaft. The data of the unified reference axis includes at least the reference axis number, axis start coordinates, axis direction vector, center offset of each detection section, residual deviation of each shaft segment, maximum residual deviation section, and effective state of the axis. The residual deviation of each shaft segment is used to characterize the degree of deviation of the equivalent rotation center point of the corresponding shaft segment from the unified reference axis, and the maximum residual deviation section is used to locate the axial position that has the greatest impact on the double-groove machining reference in the current clamping or shaft segment state.

[0037] After the unified reference axis is generated, the validity of the bearing mounting section and intermediate mating section is judged. If the maximum radial runout of any bearing mounting section is greater than 0.04 mm, it is determined that the current support or clamping state does not meet the alignment requirements for high coaxiality double groove machining, and the support pressure, center clamping force, or clamping position is readjusted. If the maximum radial runout is between 0.02 mm and 0.04 mm, the corresponding bearing mounting section is re-measured and fine-tuned. 0.04 mm is used as the re-clamping trigger threshold to identify obvious clamping eccentricity, poor center contact, or abnormal surface of the bearing mounting section. 0.02 mm to 0.04 mm is used as the fine-tuning range to handle slight runouts that can be eliminated by support adjustment.

[0038] If the maximum residual deviation of the unified reference axis is greater than 0.02mm, it is determined that the current unified reference axis is not suitable as the reference for double-slot indexing machining, and the sampling of the inspection section and the support adjustment process are returned. For motor shafts with high coaxiality, the maximum residual deviation of the unified reference axis is preferably controlled between 0.005mm and 0.015mm. This range is lower than the common coaxiality control requirement of 0.01mm to 0.03mm for precision motor bearings and rotor mating sections, and can be used as the reference error control range before subsequent double-slot indexing machining, so as to avoid the clamping deviation or segment axis offset being brought into the slot positioning during double-slot machining.

[0039] The alignment process is executed according to the following states: pending filing, sampling, data verification, axis generation, anomaly retesting, and axis locking. In the pending filing state, the part's process data is read. In the sampling state, radial runout data of each detection section is collected sequentially. In the data verification state, isolated anomalies and invalid detection sections are identified. In the axis generation state, a unified reference axis is formed. In the anomaly retesting state, abnormal detection sections are re-collected. In the axis locking state, the unified reference axis is written into the subsequent axial positioning, circumferential reference calibration, and double-groove machining process. Through the above process, the front section shaft, the intermediate mating section, and the rear section shaft form a unified machining reference under the same machining session, providing traceable reference data for subsequent double-groove angular indexing, groove correction, and post-machining verification.

[0040] S2, using a unified reference axis as the machining reference, performs axial positioning and circumferential reference calibration of the motor shaft, and establishes the angular correspondence between the double groove to be machined and the circumferential reference. The specific implementation is as follows:

[0041] After the unified reference axis is locked, the unified reference axis is called as the machining reference for axial positioning and circumferential reference position calibration, and the double groove machining data in the process drawing or machining process file is read to form a double groove process data table. The double groove process data table includes at least the following fields: machining session number, groove number, shaft segment where the groove is located, groove start axial coordinate, groove end axial coordinate, groove width, groove depth, groove bottom fillet, groove center plane design angle, double groove design angle, groove width tolerance, groove depth tolerance, groove center plane position tolerance, and angular indexing tolerance.

[0042] For example, for conventional motor shaft keyways, the slot width can be selected from 3mm to 16mm, and the slot depth can be selected from 1.5mm to 8mm; for flat slots, positioning slots, or transmission slots, the slot width and slot depth are written according to the design values ​​in the process drawings; 3mm to 16mm covers the commonly used transmission keyway width range in small to medium-sized motor shafts, and 1.5mm to 8mm matches the common keyway depth and positioning slot depth under the above slot width range. The specific dimensions are determined in conjunction with the motor shaft diameter, key connection specifications, and drawing annotations; the included angle of the double slot design can be selected as 180°, 120°, or other assembly phase angles specified in the drawings, where 180° is suitable for opposing double keyways, and non-180° is suitable for staggered positioning slots or connection structures with specific phase requirements;

[0043] When axially positioning, the bearing mounting end face, stepped end face, or the process end face specified in the drawing should be selected as the axial zero point. When using a trigger-type probe for end face inspection, the probe triggering force should be between 0.3N and 1.5N, preferably 0.8N. If the triggering force is less than 0.3N, the probe is easily affected by the cutting fluid film, oil stains, or small burrs on the end face and triggers prematurely. If the triggering force exceeds 1.5N, it is easy to create indentations on the finished end face or introduce elastic deformation of the probe, affecting the repeatability of the axial zero point.

[0044] During axial zero-point detection, the same end face position should be triggered at least three times, and the stable value among the multiple trigger results should be used as the end face coordinates. The axial positioning record should include at least the following fields: axial zero-point source, end face coordinates, repeated trigger deviation, axial compensation amount, and effective positioning mark. If the axial repeated trigger deviation is no greater than 0.005mm, the end face coordinates are confirmed as the axial zero point. If the axial repeated trigger deviation is greater than 0.005mm but no greater than 0.015mm, the end face should be re-triggered for detection, and the stable trigger value should be taken. If the axial repeated trigger deviation is greater than 0.015mm, it is determined that there are burrs, scratches, oil accumulation, or loose clamping on the end face, and the end face should be cleaned or repositioned before re-detection. 0.005mm is close to the stable repeatability requirement of precision end face trigger detection and can be used as the effective judgment limit for axial zero point. 0.015mm significantly exceeds the conventional end face trigger fluctuation range and can be used as the trigger limit for re-cleaning or repositioning.

[0045] When calibrating the circumferential reference position, read the existing process reference structure of the motor shaft; when there are marking holes, process planes, machined positioning holes or assembly marks on the end face of the motor shaft, record the circumferential angle corresponding to the structure and use it as the circumferential reference position angle; if the drawing clearly gives the angular reference, the angular reference marked on the drawing shall be the priority reference; if the drawing does not clearly give the angular reference but there are assembly marks, the assembly marks shall be used as the circumferential reference; if neither the angular reference nor the assembly marks exist on the drawing, the circumferential position corresponding to the predetermined feed direction of the first groove under the unified reference axis coordinate system shall be used as the temporary circumferential reference position, and the generation method of the circumferential reference position shall be marked in the machining record;

[0046] Circumferential angles are read via CNC indexing axis, C-axis encoder, or high-precision turntable, with an angle resolution of no less than 0.001°. Based on a common motor shaft radius of 20mm, 0.001° corresponds to a circumferential displacement of approximately 0.00035mm, which is less than the allowable deviation for conventional double-slot positions and meets the angle reading requirements before high coaxiality double-slot indexing. For motor shafts with a double-slot angular indexing tolerance of less than 0.05°, angle calibration uses a same-direction approximation method, ensuring the workpiece approaches the target angle from the same rotation direction each time to reduce the impact of gear backlash, worm gear backlash, or turntable backlash on angle calibration. Based on a radius of 20mm, 0.05° corresponds to a circumferential displacement of approximately 0.017mm, which is close to the high-precision slot control range. Therefore, under this indexing accuracy requirement, a same-direction approximation method is used for calibration.

[0047] When the turntable return backlash is greater than 0.003°, a pre-rotation angle is set, with a value ranging from 0.02° to 0.1°. 0.003° is used to determine whether the return backlash will affect high-precision indexing. 0.02° is several times this backlash value, which can cover the backlash elimination requirement. Within 0.1°, it will not significantly increase the indexing time, nor will it cause unnecessary large-scale rotation of the motor shaft. When using the pre-rotation angle, the turntable first passes the target angle and then returns to the target angle along the set direction, so that the circumferential reference position and subsequent slot indexing are completed under the condition of approximation in the same direction.

[0048] After the circumferential reference position is calibrated, an angular correspondence between the two grooves to be processed and the circumferential reference position is established. The angular position of the first groove is obtained by superimposing the circumferential reference position angle and the relative design angle of the first groove. The initial angular position of the second groove is obtained by superimposing the angular position of the first groove and the design angle between the two grooves. The superimposed angle is normalized to the range of 0° to 360° and recorded. The angular relationship table of the two grooves includes at least the following fields: circumferential reference position angle, design angle of the first groove, angular position of the first groove, design angle between the two grooves, initial angle of the second groove, indexing direction, indexing compensation status, angle reading time, angle locking status, and angle valid mark.

[0049] When there is a difference between the angle corresponding to the assembly mark and the angle designed on the drawing, check whether the angular datum on the drawing, the part assembly mark, and the machining session number correspond to the same part; if the angle difference between the assembly mark and the design on the drawing exceeds 0.5°, stop machining and record the process abnormality; 0.5° is used to identify obvious conflicts between the drawing datum, assembly mark, or manual mark, and is not used as a machining compensation threshold; calculated with a radius of 20mm, the circumferential displacement corresponding to 0.5° is about 0.175mm, which is significantly greater than the allowable range of the angular indexing error of the conventional keyway, and continuing machining is likely to cause assembly phase errors;

[0050] After axial positioning and circumferential reference position calibration are completed, an axial positioning record, a circumferential reference position record, and a double-groove angular relationship table are generated. The axial positioning record is used to determine the axial machining position of the first and second grooves, the circumferential reference position record is used to determine the starting angle of the double-groove indexing, and the double-groove angular relationship table is used to record the angular position of the first and second grooves relative to the circumferential reference position. The above data, together with the unified reference axis determined in S1, are written into the same machining session as input data for subsequent machining of the first groove, verification of the first groove, and correction of the angular indexing of the second groove.

[0051] S3, adjust the machining position of the first groove according to the offset state of each shaft segment relative to the unified reference axis, and perform milling machining on the first groove, specifically as follows:

[0052] Before machining the first groove, the unified reference axis, axial positioning record, circumferential reference position record, and double groove process data table in the same machining session are called to determine the axial machining range, angular machining position, and feed direction of the first groove; the center offset of the corresponding shaft segment relative to the unified reference axis is read according to the shaft segment where the first groove is located; when the first groove crosses the front shaft segment and the middle mating segment, or crosses the middle mating segment and the rear shaft segment, the residual deviation of the shaft segment on both sides of the cross segment position is read synchronously, and the groove start axial coordinate, groove end axial coordinate, and cross segment position are written into the first groove machining path record;

[0053] The first groove machining path record includes at least the following fields: groove number, tool number, groove start coordinates, groove end coordinates, groove width compensation, groove depth compensation, radial compensation, lateral compensation, feed direction, layered cutting depth, finishing allowance, and valid path marker. The radial compensation is used to correct the radial feed position of the tool relative to the unified reference axis, the lateral compensation is used to correct the lateral position of the tool relative to the center plane of the first groove, the groove width compensation is used to correct the machining allowance of the groove wall, and the groove depth compensation is used to correct the machining allowance of the groove bottom.

[0054] The machining position of the first groove is not based solely on the nominal outer circle center, but rather on coordinate correction by combining the offset of each shaft segment relative to a unified reference axis. When the first groove is entirely located on a single shaft segment, radial and lateral compensation amounts are generated based on the center offset of that shaft segment near the groove midpoint. When the first groove spans two shaft segments, corresponding axis points are obtained on the unified reference axis based on the axial coordinates of the groove start point, midpoint, and end point, and the offset of the equivalent rotation center point of the corresponding axial position relative to that axis point is converted into toolpath compensation amounts.

[0055] When the first groove spans different shaft segments or the groove length is long, segmented compensation nodes are set in the groove length direction. The segmented compensation nodes should include at least the node axial coordinate, node radial compensation amount, node lateral compensation amount, and node valid mark. The spacing between adjacent segmented compensation nodes should be 10mm to 30mm, preferably 20mm. A spacing of less than 10mm will result in too many CNC path segments and increase the interpolation burden. A spacing of more than 30mm may not be able to reflect the change of cross-segment axis offset in the groove length direction. 20mm is suitable for path compensation of most keyways with lengths of 30mm to 150mm.

[0056] If the lateral compensation change of adjacent segmented compensation nodes exceeds 0.01mm, an intermediate compensation node is added between the two compensation nodes; if the lateral compensation change of adjacent segmented compensation nodes is less than 0.003mm, the adjacent compensation nodes are merged; 0.01mm is close to the sensitive range of groove center plane control in high coaxiality double groove machining, adding nodes when it exceeds this value can avoid abrupt changes in tool path compensation; 0.003mm is close to the small fluctuation range in precision milling and in-machine measurement, merging nodes when it is below this value will not significantly affect the groove compensation accuracy;

[0057] The cutting tool is selected according to the width of the first groove and the material condition. When the groove width is less than 6mm, a milling cutter with a diameter 0.2mm to 0.5mm smaller than the groove width is used for rough milling, followed by finishing on both sides to form the final groove width. 6mm is used as the process boundary for machining small groove widths. This is mainly because when the groove width is small, the tool diameter is small and the tool rigidity is relatively weak. Using a milling cutter smaller than the groove width can leave a finishing allowance for both sides of the groove wall. The difference of 0.2mm to 0.5mm can form a finishing allowance of about 0.1mm to 0.25mm on each side, which is convenient for correcting tool runout and rough milling deflection. When the groove width is 6mm to 16mm, a keyway cutter or a milling cutter can be used for layered machining.

[0058] For motor shafts made of 40Cr, 42CrMo, or 20CrMnTi with a temper hardness of HRC28 to HRC35, when machining with carbide end mills or keyway cutters, the roughing depth of cut is 0.3mm to 1.0mm, the finishing allowance is 0.03mm to 0.12mm, the spindle speed is 800r / min to 2500r / min, and the feed rate is 60mm / min to 250mm / min. HRC28 to HRC35 is a common hardness range for motor shafts after tempering. A depth of cut of 0.3mm to 1.0mm can balance material removal efficiency and tool stress stability, while a finishing allowance of 0.03mm to 0.12mm can be used to correct tool deflection, elastic deformation of the groove wall, and residual steps at the bottom of the groove during the roughing stage.

[0059] For motor shafts with only a small amount of material remaining after carburizing and quenching, the first groove machining can be treated as a light finishing process, with a single-layer cutting depth of 0.05mm to 0.2mm and a reduced feed rate. This range is suitable for finishing scenarios with small allowances and high surface hardness, which can reduce the risk of tool impact and groove center plane offset. If the allowance to be machined exceeds the light finishing range, a trial cut should be performed using tools and process parameters with appropriate hardness to confirm before proceeding to formal machining.

[0060] The first slot machining process follows a sequence of states: awaiting machining, rough milling, semi-finish milling, finish milling, process inspection, and machining pause. In the awaiting machining state, the machining path record for the first slot is read, and the tool diameter, tool extension length, clamping status, and cooling status are checked. In the rough milling state, the main allowance is removed using layered cutting depths. In the semi-finish milling state, the finishing allowance is retained. In the finish milling state, the side walls and bottom of the slot are trimmed according to the compensated toolpath. In the process inspection state, the slot width, slot depth, and initial deviation of the slot center plane are checked using an in-machine probe, contact probe, or slot width detection tool. The machining pause state is used to handle cutting abnormalities, clamping abnormalities, or tool abnormalities.

[0061] During machining, the spindle load, vibration status, and cutting noise are monitored. If the spindle load exceeds 150% of the average load for stable cutting and lasts for more than 2 seconds, the feed is paused and the tool is retracted by 0.5mm to 2mm. The 150% load level can identify tool wear, poor chip removal, or sudden increase in local cutting resistance, and the 2-second duration can eliminate instantaneous cutting fluctuations. The 0.5mm to 2mm retraction amount can remove the tool from the current cutting contact area without causing excessive idle travel.

[0062] If the vibration amplitude exceeds twice the stable machining baseline of the same tool and lasts for more than 1 second, the feed rate should be reduced by 20% to 40%. The vibration amplitude of twice the baseline is used to identify continuous cutting chatter, and the duration of 1 second can eliminate short-term noise interference. Reducing the feed rate by 20% to 40% can reduce the cutting force and maintain machining continuity. If the vibration does not recover to near the stable machining baseline after two consecutive speed reductions, the machining is paused, and the clamping status, tool wear status, and the effectiveness of the compensation path are checked.

[0063] After the first groove is machined, do not release the motor shaft clamping state; only retract the tool to a safe height. The safe height is 5mm to 20mm above the maximum radius of the workpiece. 5mm is sufficient to meet the safe distance for tools of ordinary small shafts to leave the workpiece surface, and less than 20mm will not significantly increase the idle travel time. When the fixture, probe, or cooling nozzle occupies a large space, the safe height can be appropriately increased according to the machine tool's anti-collision requirements. Maintaining the original clamping state ensures that the subsequent verification of the center plane of the first groove is still based on the same unified reference axis.

[0064] After the first groove is machined, the first groove process data is generated. The first groove process data includes at least the actual tool number, actual number of cutting layers, depth of cut for each layer, feed rate for each layer, peak spindle load, final groove width measurement, final groove depth measurement, initial deviation of groove center plane, and status to be verified. The first groove process data is written into the current machining session as input data for subsequent verification of the first groove center plane and correction of the second groove angular indexing reference.

[0065] S4, detect the offset of the center plane of the first groove relative to the unified reference axis, and correct the angular indexing reference of the second groove based on the detection results. The specific implementation is as follows:

[0066] After the first groove is machined, without releasing the current clamping state, the position of the center plane of the first groove relative to the unified reference axis is checked; before checking, the process data of the first groove, the unified reference axis, the axial positioning record and the double groove angular relationship table in the same machining session are called up so that the first groove check and the second groove indexing correction use the same machining reference.

[0067] Multiple detection sections are set along the length of the first groove. When the groove length is less than 30mm, three detection sections are set, corresponding to the groove start area, the groove middle area, and the groove end area, respectively. When the groove length is 30mm to 100mm, five detection sections are set. When the groove length is greater than 100mm, seven to nine detection sections are set. For short grooves less than 30mm, the overall offset of the groove center plane can be reflected by the three positions of the start, middle, and end. For medium-length grooves of 30mm to 100mm, five detection sections are set to balance the identification and measurement efficiency of groove length skew. For long grooves of more than 100mm, they are more susceptible to tool deflection, shaft offset, and clamping elastic deformation. Setting seven to nine detection sections can identify the torsional trend of the groove center plane along the length direction.

[0068] For each detection section, position data of the left tank wall, right tank wall, and tank bottom are collected separately; no less than 3 detection points are collected on the left and right tank walls, and no less than 2 detection points are collected on the tank bottom; no less than 3 detection points on the tank wall can fit the tank wall position and reduce the influence of single-point burrs or local scratches on the detection results, and no less than 2 detection points on the tank bottom can determine the tank depth and the tank bottom tilt state; when using an in-machine probe or a contact probe for detection, the probe feed speed is between 30 mm / min and 120 mm / min, preferably 60 mm / min; below 30 mm / min will prolong the in-machine verification time, above 120 mm / min will easily increase probe impact and trigger lag, and 60 mm / min can balance detection stability and measurement cycle time;

[0069] The first groove inspection record should include at least the following fields: inspection section number, axial coordinates, left groove wall point list, right groove wall point list, groove bottom point list, measured groove width, measured groove depth, groove center plane offset, groove center plane angular offset, valid inspection mark, and deviation level. Within the same inspection section, the left groove wall position is fitted based on the left groove wall point list, and the right groove wall position is fitted based on the right groove wall point list. The groove center plane position of the inspection section is determined by the midpoint of the two groove wall positions. This position is then converted to a unified reference axis coordinate system to obtain the groove center plane offset.

[0070] When the fitted position deviation of a single detection point on the tank wall relative to other detection points on the same tank wall is greater than 0.01 mm, and there is no unidirectional offset between adjacent detection points, the detection point is marked as a local anomaly and re-acquired; 0.01 mm is close to the sensitive range of high coaxiality tank position control and can be used to identify the influence of burrs, debris, or probe triggering anomalies on the tank wall position judgment; if there are fewer than 3 effective detection points on the left or right tank wall in the same detection section, the detection section will not participate in the second tank indexing correction and will be re-verified after cleaning the tank wall;

[0071] If the measured value of the groove width at any test section exceeds the design groove width tolerance, but the absolute value of the groove center plane offset is not greater than 0.008mm, then the test section is recorded as a groove width machining deviation and is not used as the input for the second groove angular indexing compensation. If the measured value of the groove width is within the design groove width tolerance range, and the absolute value of the groove center plane offset is greater than 0.008mm, then this offset is used as the data source for the second groove angular indexing correction. If the measured value of the groove width exceeds the design groove width tolerance and the absolute value of the groove center plane offset is greater than 0.008mm, then it is first determined whether the first groove needs local trimming, and then it is decided whether to enter the second groove angular indexing correction. 0.008mm is used as the starting value for the second groove angular indexing compensation. This value is lower than half of the common lower limit of 0.02mm for high-precision motor shaft groove tolerance, which can correct the second groove indexing reference before the deviation enters the tolerance sensitive area. At the same time, this value is higher than the small fluctuation range in the in-machine measurement, which can avoid over-compensation caused by measurement noise.

[0072] The first angular deviation value of the first groove is generated based on the offset of the groove center plane of each detection section. Specifically, the radial distance from the groove center to the unified reference axis at the detection section is used as the conversion radius. Under small angle conditions, the offset of the groove center plane is divided by the conversion radius to obtain the radian value, which is then converted into an angle value as the angular offset of the groove center plane of the corresponding detection section. If the signs of the groove center plane offsets of each detection section are consistent, it is determined that the first groove has a unidirectional offset along the groove length direction. If the signs of the groove center plane offsets of the groove start area and the groove end area are opposite, it is determined that the groove center plane of the first groove has a torsional trend.

[0073] For cases of unidirectional offset, the angular offset of the center plane of the groove at each detection section is weighted according to the position of the detection section to obtain the angular deviation value of the first groove. The weight of the detection section near the bearing mounting section, the assembly stress area, or the double groove working fit area can be selected from 0.8 to 1.0, and the weight of the detection section far from the above areas can be selected from 0.6 to 0.8. The above weight settings mainly consider that the bearing mounting section and the working fit area have a greater impact on the coaxiality of the motor shaft and the stress state of the double groove. For cases with torsional tendency, the angular deviation at the starting point and the angular deviation at the ending point of the first groove are recorded respectively, and angular gradual compensation data is formed. The angular gradual compensation data includes at least the fields of starting angular deviation, ending angular deviation, compensation direction, and axial coordinate of the compensation node.

[0074] If the absolute value of the maximum center plane offset of the first groove is greater than 0.03mm, the second groove will not be processed temporarily. Instead, the finishing allowance and compensation nodes in the processing path record of the first groove will be used to locally trim the groove wall. 0.03mm is close to or exceeds the upper limit of the common range of high-precision groove tolerances. If this deviation is directly used for the indexing correction of the second groove, it is easy to transfer the processing error of the first groove to the second groove. If the absolute value of the maximum center plane offset of the first groove is greater than 0.008mm but not greater than 0.03mm, the angular indexing reference correction data for the second groove will be generated. If the absolute value of the maximum center plane offset of the first groove is not greater than 0.008mm, the initial angular position of the second groove will be used.

[0075] The second groove angular indexing datum is based on the included angle of the double groove design, and is superimposed with the angular correction amount obtained from the verification of the first groove. The angular correction amount is calculated from the offset of the groove center plane of the first groove. Under small angle conditions, the angular correction amount is equal to the offset of the groove center plane divided by the conversion radius and then converted into an angle value. For example, when the conversion radius is 15mm and the offset of the groove center plane is 0.01mm, the angular correction amount is approximately 0.038°. For same-direction offset, the angular deviation value represented by the first groove is used as the angular correction amount of the second groove. For torsional offset, the segmented angular correction amount of the second groove is generated using angular gradient compensation data.

[0076] When the absolute value of the angular correction is less than 0.005°, no actual indexing compensation is performed, and the angular correction is recorded as a minor deviation. 0.005° is greater than the previous angle reading resolution of 0.001°, but still less than one-tenth of the high-precision indexing tolerance of 0.05°, and can usually be regarded as a minor angle difference that does not require actual indexing compensation. When the absolute value of the angular correction is greater than 0.08°, the machining of the second slot is paused, and the machining status, clamping status, and effective status of the unified reference axis of the first slot are checked. 0.08° is greater than the high-precision indexing tolerance requirement of 0.05°. Calculated with a radius of 15mm, 0.08° corresponds to a circumferential displacement of about 0.021mm, which is close to the upper limit of the allowable deviation for high coaxiality double slot machining. Continuing to directly compensate may misjudge clamping changes or abnormal machining of the first slot as normal indexing deviation.

[0077] The verification of the center plane of the first slot is performed according to the following process states: pending verification, measurement, deviation classification, indexing correction, first slot finishing, and allowable indexing. In the pending verification state, the process data of the first slot and the unified reference axis are read. In the measurement state, the position data of the slot wall and the slot bottom are collected. In the deviation classification state, the source of the slot width deviation, slot depth deviation, and slot center plane offset is determined. In the indexing correction state, the angular indexing reference correction data of the second slot is generated. In the first slot finishing state, the local deviation of the first slot is corrected. In the allowable indexing state, the second slot correction data is generated. The second slot correction data includes at least the fields of second slot correction angle, correction direction, correction effective mark, and compensation node table, and is written into the current processing session as input data for subsequent second slot indexing processing.

[0078] S5, drive the motor shaft to rotate according to the corrected angular indexing reference, and perform milling on the second groove, specifically as follows:

[0079] Before machining the second groove, the second groove correction data, unified reference axis, axial positioning record, circumferential reference position record and first groove detection record in the same machining session are called; the second groove correction data includes at least the fields of second groove correction angle, correction direction, correction effective mark and compensation node table; the target angle of the second groove is determined by the initial angle of the second groove, the second groove correction angle and the correction direction, and the determined angle is normalized to the range of 0° to 360° and recorded.

[0080] When the drive motor shaft is indexed, a same-direction approximation method is adopted. When the shortest rotation direction from the current position to the target angle of the second slot is opposite to the predetermined same-direction approximation direction, the turntable first crosses the target angle of the second slot by 0.02° to 0.1°, and then returns to the target angle of the second slot along the same-direction approximation direction. The pre-rotation angle range of 0.02° to 0.1° matches the backlash elimination rule in the circumferential reference position calibration, which can cover the backlash of common precision indexing mechanisms, without significantly increasing the indexing time or causing unnecessary large-scale rotation of the motor shaft.

[0081] The indexing speed is determined based on the total axial length of the motor shaft and the clamping rigidity. When the total axial length is less than 300mm, the indexing speed is 1° / s to 5° / s; when the total axial length is 300mm to 800mm, the indexing speed is 0.5° / s to 2° / s; when the total axial length is greater than 800mm, the indexing speed is 0.2° / s to 1° / s. Short shafts within 300mm have better rigidity and can use a higher indexing speed. Motor shafts between 300mm and 800mm have a certain inertia and support deflection, so the indexing speed needs to be reduced. Long shafts over 800mm are more prone to torsional springback, support sway, or slight slippage during indexing, so using a lower indexing speed is beneficial to improving the angular stability after locking.

[0082] After the motor shaft reaches the target angle of the second slot, angle locking and indexing verification are performed. The angle locking holding time is 2s to 8s, preferably 3s to 5s. Less than 2s may not be enough to eliminate the springback of the indexing mechanism and clamping structure after indexing. More than 8s has limited improvement on stability and will prolong the machining cycle. 3s to 5s is suitable for the locking and stabilization process of common CNC indexing shafts, rotary tables and clamping mechanisms.

[0083] After locking, check sections are selected near the first groove and the corresponding shaft segments at the machining positions of the second groove, respectively, and radial runout data and circumferential angle data are collected. The check section near the first groove is used to confirm that the positional relationship of the first groove relative to the unified reference axis has not drifted after the indexing. The check section at the machining position of the second groove is used to confirm the radial state and angular position of the shaft segment to be machined.

[0084] If the absolute value of the actual angle deviation after locking is not greater than 0.005°, proceed to the second slot for processing; if the absolute value of the actual angle deviation is greater than 0.005° but not greater than 0.02°, perform a micro-angle compensation; if the absolute value of the actual angle deviation is greater than 0.02°, release the lock and re-index; 0.005° is greater than the angle reading resolution of 0.001°, but significantly lower than the high-precision indexing tolerance of 0.05°; calculated with a radius of 20mm, the circumferential displacement corresponding to 0.02° is approximately 0.007mm, which may already affect the position of the center plane of the slot, therefore, if this value is exceeded, re-indexing is required;

[0085] The second groove machining path, based on the first groove compensation path, introduces the second groove angular indexing reference correction amount and the first groove position deviation correlation data; the first groove position deviation correlation data includes at least the first groove representative angular deviation value, starting angular deviation, ending angular deviation, and angular gradient compensation data; the second groove machining path record includes at least the second groove target angle, angular correction amount, radial compensation amount, lateral compensation amount, axial compensation amount, compensation node number, compensation node axial coordinate, compensation node angle, tool path segment number, tool radius compensation value, and machining status;

[0086] When the first groove detection record shows that the center plane of the first groove is offset in the same direction along the axial direction, the second groove adopts overall angular compensation, and the angular deviation value represented by the first groove is used as the angular correction amount of the second groove; when the first groove detection record shows that the center plane of the first groove is torsional offset along the axial direction, the second groove adopts segmented angular compensation, and the corresponding node angular correction amount is read at each compensation node, and the node angular correction amount is converted into the circumferential direction compensation amount at the corresponding radius position, which is used as the lateral compensation amount of the tool path of the second groove; thus, the tool path of the second groove can be corrected along the groove length direction according to the actual groove position offset state of the first groove.

[0087] The second slot milling process employs rough milling, semi-finish milling, and finish milling. The single-layer depth of cut for rough milling of the second slot can be selected as 80% to 100% of the stable single-layer depth of cut for rough milling of the first slot. The second slot has already undergone angular indexing correction. Excessive rough milling cutting force can easily cause micro-movement of the indexing locking mechanism. Therefore, the rough milling depth of cut for the second slot is usually not higher than the stable depth of cut for the first slot. When abnormal vibration or abnormal spindle load is recorded during the machining of the first slot, the single-layer depth of cut for rough milling of the second slot is set to 60% to 80% of the stable depth of cut for the first slot to reduce cutting force and improve machining stability after indexing and locking.

[0088] The feed rate for the second groove can be selected as 80% to 110% of the stable feed rate for the first groove. This range is adjusted around the stable feed rate for the first groove to maintain consistency in the machining conditions of the first and second grooves and to accommodate the rigidity differences of the shaft segment where the second groove is located. If the rigidity of the shaft segment where the second groove is located is lower than that of the shaft segment where the first groove is located, or if the second groove is located near the cross-section connection area, the feed rate is taken at the lower limit of the above range to reduce the risk of tool deflection, vibration, and groove center plane offset.

[0089] Before machining the second groove, the current clamping state is not changed; if the clamping force or clamping force needs to be adjusted due to the stability of the workpiece, the unified reference axis is rechecked after the adjustment, and machining continues when the unified reference axis still meets the effective state; this process can avoid the motor shaft axis from shifting again due to changes in clamping force or clamping force, which would cause the machining reference of the second groove to be inconsistent with the verification reference of the first groove.

[0090] The second slot machining is performed according to the following process states: pending indexing, indexing in progress, locking verification, path generation, rough milling of the second slot, semi-finish milling of the second slot, finish milling of the second slot, and abnormal retraction. In the pending indexing state, the second slot correction data is read. In the indexing in progress state, the drive motor shaft reaches the target angle of the second slot. In the locking verification state, the actual angle deviation and radial status are judged. In the path generation state, the tool path of the second slot is formed according to the compensation node table. The second slot rough milling, second slot semi-finish milling, and second slot finish milling states complete the slot machining in sequence. The abnormal retraction state is used to handle locking failure, angle drift, cutting vibration, and tool wear.

[0091] During the second slot machining process, continue to monitor angle drift, spindle load, and vibration status. If an angle drift exceeding 0.01° is detected, pause the feed and retract the tool, relock, and verify the angular position. 0.01° is twice the 0.005° threshold for direct machining after locking, which can identify angle drift caused by cutting force. At the same time, it is below the 0.02° threshold for re-indexing, making it suitable as a trigger value for pausing and verifying during machining. If the angle drift accumulates to twice within the same machining session, mark the indexing and clamping status as abnormal and pause the second slot finishing process to verify the indexing and locking mechanism, clamping status, and tool cutting status.

[0092] After the second groove is machined, the second groove process data is generated. The second groove process data includes at least the following fields: actual target angle of the second groove, actual indexing angle, angle deviation after locking, actual tool number, number of cutting layers, depth of cut of each layer, feed rate of each layer, angle drift record, peak spindle load, vibration anomaly record, final groove width measurement value, final groove depth measurement value, and status pending final inspection. The second groove process data is written into the current machining session as the data basis for subsequent double groove position verification and compensation adjustment.

[0093] S6, detect the position status of the first and second slots relative to the unified reference axis, and compensate and correct the slot position deviation based on the detection results. The specific implementation is as follows:

[0094] After the first and second slots are machined, a final inspection and compensation adjustment of the dual slots are performed under the current clamping state. The final inspection data sources include at least the unified reference axis, the first slot inspection record, the second slot process data, the second slot inspection record, the dual slot process data table, and the dual slot angular relationship table. The second slot inspection record is generated according to the inspection method of the first slot inspection record and includes at least the measured value of the second slot width, the measured value of the second slot depth, the offset of the second slot center plane, the angular offset of the second slot center plane, the valid inspection mark, and the deviation level.

[0095] The final inspection objects include the center plane of the first slot, the center plane of the second slot, the included angle between the two slots, the offset of the center plane of the two slots relative to the unified reference axis, the difference in the depth of the slot bottom, the difference in the width of the slot, and the deviation in the direction of the slot length. The number of inspection sections is the same as the number of inspection sections when checking the center plane of the first slot. Inspection sections are taken at the same axial coordinate position of the first and second slots to form a one-to-one slot position comparison data. If the slot lengths of the first and second slots are different, the corresponding inspection sections are set based on the overlapping axial range of the two slots, and supplementary inspection sections are set separately in the non-overlapping area.

[0096] The dual-slot status table should include at least the following fields: processing session number, inspection section number, axial coordinate, offset of the center plane of the first slot, offset of the center plane of the second slot, measured angle of the dual slots, design angle deviation, depth of the first slot, depth of the second slot, difference in depth, width of the first slot, width of the second slot, difference in width, slot level, trimming suggestion, and final inspection status. The slot level should be judged in the order of not allowing further processing, requiring realignment, qualified, and trimmable to avoid misjudging workpieces whose dimensions have exceeded the limits or whose reference has drifted as being able to continue trimming.

[0097] When the groove width exceeds the design upper limit, the groove depth exceeds the design lower limit, or the absolute value of the offset of any groove center plane is greater than 0.05mm and there is no room for adjustment, the groove grade is marked as not allowing further processing; 0.05mm is close to the upper limit of the common tolerance range of 0.02mm to 0.05mm for high-precision motor shaft grooves. Continuing to expand the groove width through sidewall finishing is likely to cause an increase in the fit clearance, so it is used as a judgment value for not being suitable for further processing;

[0098] When the offset directions of the first and second slots relative to the unified reference axis are consistent, and the absolute value of the angular deviation between the two slots is not greater than 0.02°, the radial runout data of the bearing mounting section or intermediate mating section should be re-acquired; if the maximum radial runout change obtained by re-measurement exceeds 0.01mm, the slot level should be marked as needing to be recalibrated; 0.01mm is close to the sensitive range of high coaxiality slot control and can be used to identify changes in clamping status, changes in top support, or drift of the unified reference axis;

[0099] When the absolute value of the included angle deviation of the two slots is not greater than 0.02°, the absolute value of the offset of the center plane of the first and second slots is not greater than 0.015mm, the difference in slot depth is not greater than 0.02mm, and the slot width is within the design slot width tolerance range, the slot grade is marked as qualified. 0.02° corresponds to a circumferential displacement of approximately 0.007mm with a radius of 20mm, which is lower than the common lower limit of high-precision slot tolerance of 0.02mm, and is suitable as the qualified judgment limit for the included angle of the two slots. 0.015mm is lower than the lower limit of the slot tolerance range of 0.02mm to 0.05mm, and is suitable as the control value for the center plane of the high-precision slot. A slot depth difference of 0.02mm can take into account both the consistency of the mating depth of common keyways and the stability of in-machine measurement.

[0100] If the conditions for qualification are not met and the groove width and depth are still within the adjustable range, if the absolute value of the offset of the groove center plane is no greater than 0.03mm, the groove level is marked as adjustable. 0.03mm is in the middle range of the common tolerance range of high precision grooves. If there is still a machining allowance, it can be adjusted by a small amount of fine finishing on the side wall or a light cutting of the groove bottom. If the absolute value of the offset exceeds 0.03mm, it is first determined whether there is a reference drift or clamping change, and the groove width is not directly increased for compensation.

[0101] Before compensation and adjustment, first determine the type of deviation; if the first and second slots are offset in the same direction relative to the unified reference axis, and the absolute value of the angular deviation between the two slots is not greater than 0.02°, then it is preferentially determined that there is an overall drift between the unified reference axis and the current clamping state, and the unified reference axis is returned for verification; if the absolute value of the offset of the center plane of the first slot is not greater than 0.008mm, the absolute value of the offset of the center plane of the second slot is greater than 0.008mm, and the absolute value of the angular deviation between the two slots exceeds 0.02°, then it is preferentially determined that there is a deviation in the indexing or locking of the second slot, and the adjustment object is the wall of the second slot;

[0102] If the difference in width between the first and second slots exceeds 50% of the design slot width tolerance zone, but the absolute value of the offset of the center plane of both slots is no greater than 0.008mm, it is primarily determined to be tool wear or tool radius compensation setting deviation, and the adjustment targets are the slot width and the slot wall surface; if the difference in bottom depth exceeds 0.02mm, and the absolute value of the offset of the center plane of both slots is no greater than 0.008mm, the adjustment targets are the bottom depth, without changing the position of the center plane of the slot; 0.008mm is consistent with the starting value of the second slot angular indexing compensation, and can be used as the boundary for judging whether the center plane of the slot enters the compensation sensitive zone;

[0103] The compensation and trimming process generates a trimming path in the order of angular deviation, then lateral deviation, and then depth deviation. Angular deviation trimming is completed by micro-milling one side wall of the target groove. The trimming amount for a single side wall is between 0.005mm and 0.02mm. 0.005mm can form a controllable micro-trimming, while 0.02mm is close to the upper limit of a single side wall trimming. Exceeding this value can easily cause excessive changes in groove width and affect the key connection fit.

[0104] Lateral deviation correction is completed by fine finishing on both sides with unequal amounts. The maximum correction amount on one side shall not exceed 60% of the remaining groove width tolerance. This proportion can retain at least 40% of the groove width tolerance as a margin for post-correction re-inspection and secondary correction, avoiding exhausting the groove width tolerance in one correction. Groove bottom depth correction is completed by light cutting at the bottom of the groove, with a single cutting amount of 0.005mm to 0.03mm. 0.005mm is suitable for removing residual steps or slight depth deviations at the bottom of the groove, while 0.03mm or less can control the groove depth change and reduce the risk of groove depth exceeding tolerance in one cutting.

[0105] If the remaining tolerance of the slot width is less than 0.01mm, the sidewall trimming will not be performed, and the current motor shaft will be marked as a process verification part and transferred to manual process verification or rework evaluation. 0.01mm is close to the lower limit of slot width fine trimming and in-machine measurement fluctuation. If the remaining tolerance is less than this value, continuing to trim the sidewall will easily cause the slot width to exceed the design tolerance.

[0106] Final inspection and finishing are performed according to the following process states: final inspection preparation, dual-groove measurement, deviation judgment, finishing path generation, compensation finishing, post-finish re-inspection, archiving end, and abnormal termination. In the final inspection preparation state, previous machining and inspection records are read. In the dual-groove measurement state, the first and second groove position data are collected. In the deviation judgment state, the groove position level and deviation type are generated. In the finishing path generation state, the toolpath is formed based on the deviation type, remaining tolerance, and adjustable allowance. In the compensation finishing state, minor grooving is performed. In the post-finish re-inspection state, the finished area is measured again. In the archiving end state, a complete machining record is output. In the abnormal termination state, the reason for the inability to finish is recorded.

[0107] The post-repair re-inspection shall be performed in a maximum of two rounds. The first round of re-inspection is used to confirm the status of the slot after the initial repair, and the second round of re-inspection is used to confirm the status of the slot after the supplementary repair. If the corresponding slot grade requirements are still not met after two rounds of re-inspection, the repair amount shall be stopped and recorded as an abnormal termination status. Two rounds of re-inspection can cover one repair and one supplementary repair. Continuing to increase the number of repair rounds may easily cause the slot width or slot depth to exceed the tolerance.

[0108] The double-groove indexing machining record includes at least the following fields: unified reference axis number, axial positioning record number, circumferential reference position record number, first groove process data number, first groove inspection record number, second groove process data number, second groove inspection record number, double groove position status table number, compensation and adjustment record number, final groove position level, and traceable timestamp. This record is bound to the motor shaft part number and is used for subsequent assembly, quality verification, and machining traceability.

[0109] In one embodiment, a 42CrMo segmented motor shaft for a new energy vehicle drive motor is used as the machining object. This motor shaft is formed by connecting a front shaft, a middle mating section, and a rear shaft, and requires machining 180° opposing double grooves on the shaft extension connection section. Before machining, the motor shaft is installed in a clamp-and-top support structure, allowing it to rotate at low speed. Radial runout data of the front shaft, middle mating section, and rear shaft are collected, and a unified reference axis running through the entire length of the motor shaft is determined based on the equivalent rotation center of each detection section. Subsequently, using the unified reference axis as the machining reference, the bearing mounting end face is selected as the axial zero point, and the circumferential reference position is determined in conjunction with the end face assembly marks. An angular correspondence between the first groove, the second groove, and the circumferential reference position is established. When machining the first groove, the location of the first groove is considered... The tool path is corrected by adjusting the offset of the shaft segment relative to the unified reference axis, so that the machining position of the first groove matches the actual axis state of the segmented motor shaft. After the first groove is machined, the offset of the center plane of the first groove is detected without releasing the current clamping state, and this offset is converted into the angular correction amount of the second groove. Subsequently, the motor shaft is driven to rotate according to the corrected angular indexing reference, and the second groove is machined after angle locking and rotation verification. After both the first and second grooves are machined, the angular included angle, the offset of the center plane of the groove, the groove width difference, and the groove depth difference are detected again under the same clamping state. Based on the detection results, the correctable deviations are finely milled or the groove bottom is lightly cut to form a double groove indexing machining record corresponding to the part number of the motor shaft, which is used for subsequent assembly, quality verification, and machining traceability.

[0110] It should be noted that this invention can be deployed on the device itself to realize embedded applications, or it can run on a PC or other terminal with a user interface, thereby meeting various hardware environments and usage requirements.

[0111] The above embodiments can be implemented in whole or in part by software, hardware, firmware, or any other combination. When implemented in software, the above embodiments can be implemented in whole or in part by a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, the processes or functions of the embodiments of this application are implemented in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted wirelessly or wiredly from one website, computer, server, or data center to another website, computer, server, or data center. Wired methods include optical fiber, twisted pair, coaxial cable, etc. Wireless methods include infrared, microwave, etc. Available media include any available media that can be accessed by a computer or data storage devices such as servers and data centers that contain one or more sets of available media. Available media can be magnetic media (floppy disks, hard disks, magnetic tapes), optical media (DVDs), or semiconductor media. Semiconductor media can be solid-state drives.

[0112] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0113] In conclusion, 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.

Claims

1. A method for double-groove indexing machining of motor shafts with high coaxiality requirements, characterized in that, include: S1, obtain the radial runout states of the front section, middle mating section and rear section of the segmented motor shaft respectively, and determine the unified reference axis through the motor shaft based on the alignment state of each shaft segment; S2, using a unified reference axis as the machining reference, performs axial positioning and circumferential reference position calibration of the motor shaft, and establishes the angular correspondence between the double groove to be machined and the circumferential reference position; S3, adjust the machining position of the first groove according to the offset state of each shaft segment relative to the unified reference axis, and perform milling machining on the first groove; S4, detect the offset of the center plane of the first groove relative to the unified reference axis, and correct the angular indexing reference of the second groove according to the detection result; S5, drive the motor shaft to rotate according to the corrected angular indexing reference, and perform milling on the second groove; S6 detects the position status of the first and second slots relative to the unified reference axis, and compensates and corrects the slot deviation based on the detection results.

2. The method for double-groove indexing machining of motor shafts with high coaxiality requirements according to claim 1, characterized in that, S1 includes: When obtaining the radial runout state, the motor shaft is mounted on a two-center support structure or a clamp-and-center support structure, and the motor shaft is driven to rotate at low speed. Multiple detection sections are arranged along the axial direction of each shaft segment, and circumferential equal-angle sampling is performed at each detection section; The sampled data underwent outlier retesting and validity verification. The unified reference axis is determined based on the equivalent rotation center and functional weight of each test section.

3. The method for double-groove indexing machining of motor shafts with high coaxiality requirements according to claim 1, characterized in that, S2 includes: When axial positioning and circumferential reference calibration, read the double groove process data table, and use a trigger probe to repeatedly test the bearing mounting end face, step end face or process end face to stabilize the trigger position as the axial zero point. Determine the circumferential reference position based on the angular reference of the drawing, assembly marks, or the predetermined feed direction of the first groove, and read the circumferential angle using the same-direction approximation method. Use the circumferential reference position as the starting point to determine the angular position of the first groove and the initial angle of the second groove.

4. The method for double-groove indexing machining of motor shafts with high coaxiality requirements according to claim 1, characterized in that, S3 includes: During the first slot milling process, the axial positioning record, circumferential reference position record, and double slot process data table are called. Determine the radial compensation amount, lateral compensation amount, and segmented compensation nodes based on the location of the shaft segment and span of the first groove; Select the milling tool, layer cutting depth, and feed parameters according to the width of the first slot and the material condition of the motor shaft; Monitor spindle load, vibration status, and cutting noise during machining.

5. The method for double-groove indexing machining of motor shafts with high coaxiality requirements according to claim 1, characterized in that, S4 includes: After the first groove is processed, a detection section is set along the length of the first groove while keeping it clamped. Collect position data of the left tank wall, right tank wall and tank bottom, and determine the offset of the tank center plane based on the fitted position of the left tank wall and right tank wall; The offset of the center plane of the groove is converted into an angular deviation value according to the radius of the groove; The second groove's overall angular compensation data or segmented angular compensation data are generated based on the angular deviation direction of each detection section.

6. The method for double-groove indexing machining of motor shafts with high coaxiality requirements according to claim 1, characterized in that, S5 includes: During the machining of the second groove, the target angle of the second groove is determined based on the correction data of the second groove. The motor shaft is driven to rotate in the same direction and the angle is locked and checked. The overall compensation path is generated based on the angular deviation value represented by the first groove, or the segmented compensation path is generated based on the angular gradient compensation data, and rough milling, semi-finish milling and finish milling are performed in sequence, while monitoring angular drift, spindle load and vibration status.

7. The method for double-groove indexing machining of motor shafts with high coaxiality requirements according to claim 1, characterized in that, S6 includes: After the double-groove machining is completed, the first groove detection record is called and the second groove detection record is generated under the current clamping state. The angular angle, groove center plane offset, groove width difference and groove depth difference of the first and second grooves are compared according to the same axial coordinate. The trimming path is formed according to the groove level and deviation type, and trimming is performed in the order of angular deviation, lateral deviation and depth deviation.

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