High-speed motor rotating shaft with dynamic balance and wear resistance and processing method thereof

Abstract

The application discloses a high-speed motor rotating shaft with dynamic balance and wear resistance and a processing method thereof, and relates to the technical field of motor processing. The method comprises the following steps: step 1: a combined process of deep hole drilling with double-end guide sleeve positioning, ultrasonic vibration deburring and outer circle fine grinding is adopted to process a tubular structure middle shaft, so that the middle shaft with the inner hole straightness of less than or equal to 0.005 mm, the outer circle roundness of less than or equal to 0.003 mm and the coaxiality of less than or equal to 0.004 mm is obtained; and step 2: a combined process of high-speed precision turning, diamond reamer reaming and fine turning of the matching surface is adopted to process end shafts, and an axial oil inlet hole is arranged in one of the end shafts and chamfered. The combined processing process of deep hole drilling with double-end guide sleeve positioning, ultrasonic vibration deburring and outer circle fine grinding of the middle shaft is arranged, the problems of large inner hole straightness deviation, burr residue and excessive outer circle roundness of the middle shaft are avoided, a high-precision foundation is laid for subsequent assembly and dynamic balance, and the centrifugal force deviation during high-speed rotation is significantly reduced.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of motor machining, in particular to a high-speed motor rotating shaft with dynamic balance and wear resistance and a machining method thereof. BACKGROUND

[0002] As a core power equipment in the modern industrial field, high-speed motors are widely used in precision manufacturing, new energy vehicles, aerospace, rail transit and other key scenes. Its core advantages are high speed, high power density and high efficiency, which can output strong power in a compact structure size, meeting the stringent requirements of modern equipment for lightweight and high performance. With the continuous upgrading of industrial technology, the operating speed of high-speed motors continues to increase, and in some scenes, it has broken through 10,000 r / min, which puts higher requirements on the performance of the core parts of the motor, especially in stability, wear resistance and service life.

[0003] The rotating shaft is a core transmission and support component of the high-speed motor, which directly bears the key functions of power transmission, rotor positioning and cooperation with the cooling system to realize heat dissipation. The existing high-speed motor rotating shaft adopts a three-section structure of a first end shaft, a middle shaft and a second end shaft, wherein the middle shaft is designed as a tubular cavity structure, the first end shaft is provided with an oil inlet hole in the axial direction, and the side wall of the middle shaft is provided with an oil outlet hole. The circulating flow of the cooling oil in the cavity carries away a large amount of heat generated during the operation of the motor, avoiding component failure due to overheating. The performance of the rotating shaft directly determines the operating stability, transmission efficiency and service life of the high-speed motor. The dynamic balance precision affects the shaking amplitude during the operation of the motor, the wear resistance is related to the wear loss after long-term use, and the connection strength determines the safety and reliability of the motor under high load working conditions.

[0004] However, the existing machining process of the high-speed motor rotating shaft still has many defects, which makes it difficult to adapt to the actual use requirements of high speed and high load: first, the dynamic balance precision is insufficient. In the existing machining process, the key precision indicators such as the straightness of the middle shaft inner hole and the perpendicularity of the end shaft fitting surface are not effectively controlled, the welding process is extensive and easy to cause deformation and internal stress concentration, and no specific multi-stage balance correction link is set, which leads to excessive unbalance of the rotating shaft during high-speed operation, causing obvious shaking, aggravating bearing wear and motor noise; second, the wear resistance is weak. The outer surface of the rotating shaft is not specially treated, and is easy to wear and peel off after long-term friction with the bearing and sealing element. The welded joint as a weak structure part has no special wear protection, which is easy to cause the connection strength to decrease due to wear failure. Therefore, the high-speed motor rotating shaft with dynamic balance and wear resistance and the machining method thereof are proposed to solve such problems. SUMMARY

[0005] Technical problems solved

[0006] In view of the deficiencies of the prior art, the application provides a high-speed motor rotating shaft with dynamic balance and wear resistance and a processing method thereof, and solves the problems in the background art.

[0007] Technical scheme

[0008] To achieve the above object, the application is implemented by the following technical scheme: a high-speed motor rotating shaft processing method with dynamic balance and wear resistance, as shown in the accompanying drawings, comprising: Figure 1

[0009] First, a 45 seamless steel pipe with an outer diameter of 50mm and an inner diameter of 30mm is selected as the original material of the shaft, which has good comprehensive mechanical properties and processing performance and is a commonly used high-quality material for shaft parts in the mechanical manufacturing field. Quenching at 840℃ for 1.5 hours and then water quenching, and then tempering at 580℃ for 2 hours and then air cooling are used for quenching and tempering treatment. The quenching and tempering treatment refines the material grains, improves the toughness and hardness uniformity of the material, and finally obtains a shaft blank with a hardness of 220-250HB. This hardness range can not only ensure the easy operability of subsequent processing, but also meet the structural strength requirements during high-speed rotation.

[0010] Then, the quenched and tempered shaft blank is fixed in the double-end guide sleeve tool of the deep hole drilling machine. The double-end guide sleeve is made of Cr12MoV material and has a hardness of 60HRC, which has good wear resistance and positioning accuracy. Drilling is performed at a drilling speed of 80-120 meters per minute and a feed rate of 0.15mm per revolution. This parameter combination can ensure drilling efficiency while reducing vibration and hole diameter deviation during drilling, ensuring the quality of the inner hole processing.

[0011] Then, the drilled shaft is fixed on the ultrasonic vibration workbench, and the ultrasonic vibration equipment is turned on. Deburring is performed at an ultrasonic frequency of 28kHz and a deburring time of 3-5 minutes. Ultrasonic vibration can produce high-frequency micro-vibration, which can make the burrs on the inner hole and hole fall off under the vibration impact. Compared with the traditional mechanical deburring method, it can more thoroughly remove the fine burrs without damaging the inner hole surface.

[0012] Finally, the deburred shaft is placed in the grinding station of the centerless grinding machine, and white corundum grinding wheel (grit 80#) is selected. The outer circle is precisely ground at a grinding speed of 30 meters per second and a feed rate of 0.01mm per revolution. During the precise grinding process, the guide wheel and the supporting plate of the centerless grinding machine are used to realize the stable support and uniform rotation of the shaft, ensuring the uniformity of the outer circle processing. After precise grinding, the roundness of the outer circle of the shaft is detected by a roundness instrument, and the coaxiality of the two ends of the shaft is detected by a coaxiality detector. When the outer circle roundness is ≤0.003mm and the coaxiality is ≤0.004mm, the shaft is transported to the assembly station of step 3 and enters the subsequent assembly and welding process.

[0013] ​In this scheme, the 45 seamless steel tube can provide stable mechanical properties after quenching and tempering treatment, the double-end guide sleeve positioning drilling can effectively ensure the straightness of the inner hole, the ultrasonic vibration deburring can completely remove the residual burrs, and the centerless grinding machine fine grinding can improve the outer circle precision. The synergistic effect of multiple processes finally obtains a high-precision middle shaft with inner hole straightness ≤0.005mm, outer circle roundness ≤0.003mm and coaxiality ≤0.004mm, which provides reliable protection for the accurate assembly with the end shaft and the overall dynamic balance performance.

[0014] After the middle shaft drilling is completed, the detection probe of the laser diameter measuring instrument is immediately inserted into the middle shaft inner hole, and 5 detection points are uniformly selected along the inner hole axis direction. The inner hole diameter and straightness data of each point are measured, and the detection results are compared with the preset straightness ≤0.005mm standard. After confirming that the straightness meets the standard, the middle shaft is transferred to the ultrasonic vibration deburring station for subsequent processing, avoiding invalid processing of subsequent processes due to drilling precision not meeting the standard.

[0015] After the middle shaft outer circle fine grinding is completed, the roundness of the middle shaft outer circle is detected by using a roundness instrument on any 3 different sections. 8 evenly distributed detection points are selected on each section, and the roundness error of each section is calculated. Then, the coaxiality error of the middle shaft at both ends is detected by using a coaxiality detector. After confirming that the outer circle roundness is ≤0.003mm and the coaxiality is ≤0.004mm, the middle shaft is cleaned and labeled, and is transferred to the assembly station of step 3 to ensure that the middle shaft precision entering the assembly process completely meets the design requirements.

[0016] In this scheme, special detection links are set in stages, which can timely find the precision deviation in the drilling and fine grinding process, avoid unqualified semi-finished products flowing into subsequent processes, reduce processing cost waste, and at the same time, through the detection method of multiple detection points and multiple sections, the accuracy and reliability of the middle shaft precision detection results are ensured, laying a foundation for subsequent assembly quality and overall performance.

[0017] Step 2: First select a 40Cr alloy steel round steel with a diameter of 80mm as the end shaft raw material. The 40Cr alloy steel has higher strength, toughness and hardenability than the 45 steel, which can meet the mechanical performance requirements of the end shaft as a connecting and supporting component. After normalizing treatment according to the parameters of temperature 860℃ for 2 hours, cooling to 300℃ in the furnace and then air cooling to room temperature, the normalizing treatment can refine the material grains, eliminate the organizational defects of the raw material, and improve the processing performance and mechanical performance uniformity of the material.

[0018] Then the end shaft blank after normalizing is clamped on the three-jaw chuck of the numerical control lathe, and a PCBN tool (model CNMG120408) is selected. The tool has high hardness and good wear resistance, is suitable for high-speed cutting of alloy steel materials, and is used for turning the outer surface of the end shaft at a cutting speed of 200 meters per minute and a feed rate of 0.08 millimeters per revolution. High-speed precision turning can effectively reduce the influence of cutting force and cutting heat on the surface quality of the end shaft. After turning, the surface roughness instrument is used to detect four detection points evenly selected on the outer surface of the end shaft. After confirming that the surface roughness Ra is less than or equal to 0.4 microns, the oil inlet hole drilling process is performed.

[0019] In the scheme, the 40Cr alloy steel has excellent comprehensive mechanical properties after normalizing treatment. The PCBN tool cooperates with the high-speed precision turning parameters to realize high-precision machining of the outer surface of the end shaft. The design of the surface roughness Ra less than or equal to 0.4 microns can reduce the frictional resistance when the end shaft cooperates with other parts, and improve the transmission efficiency and running stability of the rotating shaft. The phased detection can ensure that the machining quality of the outer surface of the end shaft meets the standards.

[0020] When drilling the axial oil inlet hole, the end shaft is first fixed in the special tooling of the numerical control lathe. A high-speed steel twist drill with a diameter of 10 mm is used for drilling, and a guide sleeve is used for positioning. The guide sleeve can ensure the drilling accuracy of the drill bit and prevent the drill bit from deviating during drilling, which can cause the oil inlet hole to be inclined. After drilling, an H7 grade diamond reamer is replaced, and the reaming process is performed at a reaming speed of 15 meters per minute and a feed rate of 0.1 millimeters per revolution. The diamond reamer has high hardness and sharp cutting edges, which can effectively improve the smoothness of the inner wall of the oil inlet hole and ensure that the hole wall roughness Ra is less than or equal to 0.8 microns.

[0021] When chamfering the oil inlet hole, a forming turning tool is installed on the numerical control lathe. The feed path and angle of the turning tool are controlled by the program to obtain a 1x45° chamfer. The chamfer size can avoid sharp corners at the oil inlet hole, prevent vortex and resistance during the flow of cooling oil, and protect the inner wall of the cooling oil passage from being scratched.

[0022] When machining the mating surface of the end shaft and the middle shaft, face turning is performed at a cutting speed of 150 meters per minute and a feed rate of 0.05 millimeters per revolution. After turning, the detection head of the perpendicularity detector is attached to the mating surface, and the end shaft is slowly rotated for one revolution. The perpendicularity deviation data is read, and the perpendicularity is confirmed to be less than or equal to 0.002 mm. Then, a plug gauge is inserted into the mating gap between the end shaft and the middle shaft to detect the size of the mating gap, ensuring that the gap is within a reasonable range of 0.01-0.02 mm.

[0023] In the scheme, the combination process of guide sleeve positioning drilling and diamond reaming can ensure the size accuracy and inner wall smoothness of the oil inlet hole, the 1x45° chamfer design optimizes the cooling oil flow effect, the high-precision turning of the mating surface and the double detection can ensure the assembly fit of the end shaft and the middle shaft, reduce the stress concentration after assembly, and improve the structural stability and transmission efficiency of the connection part.

[0024] Step 3: Select a positioning tool with three-jaw centering structure during assembly, which has automatic centering function, high positioning accuracy and convenient operation. First, detect the coaxiality error of the tool itself, ensure that it is ≤0.002mm, then put the first end shaft, middle shaft and second end shaft into the tool in turn, and check the outer surface of each part by using a dial gauge. Slowly rotate the tool to correct and adjust the position of each part, so that the axis deviation of the first end shaft, middle shaft and second end shaft is ≤0.003mm, ensuring the assembly coaxiality.

[0025] When welding, use a fiber laser welding machine. First, set the pulse laser power to 1.2-1.8kW, the welding speed to 3-5mm / s, and the pulse frequency to 50-80Hz. This parameter combination can reduce the heat input of single welding and reduce the risk of welding deformation. Then, introduce argon gas with a flow rate of 15L / min as a protective gas. Argon gas can isolate air and prevent the welding area from being oxidized. Complete multi-layer and multi-pass welding according to the standard of 0.8-1.2mm per layer thickness. Multi-layer and multi-pass welding can evenly distribute welding heat and improve the strength and density of the welded joint.

[0026] During stress relief heat treatment, place the welded overall rotating shaft into a box-type resistance furnace and slowly heat it at a rate of 5℃ / min to avoid temperature difference stress caused by rapid heating. Heat it to 280-320℃ and keep it for 1.5-2 hours to fully release the internal stress of the welding area. Then, cool it to room temperature at a rate of 2℃ / min. Slow cooling can further reduce new stress generated during the cooling process. After cooling, use the probe of a stress detector to detect the internal stress value of the welding area. If the internal stress is ≤80MPa, transfer the rotating shaft to the dynamic balance detection station of step 4.

[0027] In the scheme, the three-jaw centering positioning tool can ensure the assembly coaxiality, the pulse laser multi-layer and multi-pass welding with argon gas protection can improve the welding quality and reduce welding defects, and the customized stress relief heat treatment process can effectively eliminate welding internal stress and reduce welding deformation to ≤0.003mm, significantly improving the connection strength and structural stability of the end shaft and the middle shaft, and preventing brittle cracking of the welded part during high-speed operation.

[0028] Step 4: When drilling the weight-removing hole by electric spark machining, first mark the position of the unbalance according to the unbalance position and unbalance amount detected by the hard support dynamic balancing machine, and mark the position in the non-matching area of the end shaft end face. The marking position should be offset from the center axis of the end shaft by a distance not less than 1 / 3 of the radius of the end shaft. This position is designed to avoid the weight-removing area being close to the matching surface to affect the assembly precision. At the same time, the parameters of the drilling diameter of 2-4 mm and the depth of 3-5 mm are set. The number of single drilling should not exceed 3 to prevent the structure strength of the end shaft from being affected by too many drilling holes.

[0029] In step 7, when laser marking micro weight-removing, a fiber laser marking machine is selected. First, set the parameters of spot diameter ≤2 mm and depth ≤1 mm. This parameter can achieve precise micro weight-removing. Then control the single weight-removing amount not to exceed 0.5 g to avoid damaging the surface strengthening coating due to excessive weight-removing amount. The weight-removing area is limited to the non-matching area of the end shaft end face to ensure that the weight-removing process does not affect the assembly performance and appearance quality of the rotating shaft.

[0030] In this scheme, precise positioning of the weight-removing position and reasonable setting of the weight-removing parameters can effectively eliminate the unbalance of the rotating shaft while maximizing the protection of the structure strength and surface coating of the end shaft. The two dynamic balancing corrections are respectively for the rotating shaft after welding and after surface strengthening to ensure that the final unbalance is ≤2 g·mm / kg, improve the stability of the rotating shaft during high-speed operation, and reduce shaking and noise.

[0031] Step 5: When high-pressure kerosene flushing, first set the pressure to 15-20 MPa. This pressure can effectively flush the loose impurities in the inner cavity and welding gap. Then insert the cleaning needle from the oil inlet hole to the other end shaft and inject high-pressure kerosene for continuous flushing for 5 minutes. During the flushing process, slowly rotate the rotating shaft to make the high-pressure kerosene flow through every area of the inner cavity to ensure that there is no dead angle in the flushing process.

[0032] When ultrasonic cleaning, first configure a mixed cleaning solution of kerosene and 5% cleaning agent. Kerosene has good decontamination ability, and the cleaning agent can enhance the cleaning effect. Then put the rotating shaft into the ultrasonic cleaning tank so that the cleaning solution completely covers the rotating shaft by 50 mm. Perform cleaning according to the parameters of frequency 40 kHz and cleaning time 10 minutes. The high-frequency vibration generated by the ultrasonic wave can strip the tiny impurities attached to the surface of the welding gap and the inner cavity. During the cleaning process, the rotating shaft is turned over every 2 minutes to ensure that all parts are thoroughly cleaned.

[0033] When compressed air is used for drying, first set the parameters of compressed air pressure 0.6 MPa and dew point ≤-40℃. A dew point ≤-40℃ can avoid the residual water in the compressed air causing corrosion in the inner cavity of the rotating shaft. After continuous drying for 3 minutes, use a dryness detector to detect the dryness of the inner cavity of the rotating shaft. After confirming that there is no water residue, the cleaning process is completed.

[0034] In step 6, when spraying the ceramic coating, ceramic powder with a mass ratio of alumina (chemical formula Al2O3, the stoichiometric ratio of aluminum atoms to oxygen atoms is 2:3) and titanium dioxide (chemical formula TiO2, the stoichiometric ratio of titanium atoms to oxygen atoms is 1:2) is 90:10. The ceramic coating with this ratio has high hardness and good toughness, which can improve the wear resistance of the outer surface of the rotating shaft. When cladding the Ni-based alloy coating, Ni60A alloy powder with a particle size of 50-100 μm is selected. Ni60A alloy powder has excellent wear resistance and bonding performance with the substrate, which can enhance the wear resistance and fatigue strength of the welded joint.

[0035] In this scheme, the synergistic process of high-pressure kerosene flushing and ultrasonic cleaning can completely remove impurities with a diameter of >5 μm in the inner cavity and welding gap, avoid impurities forming local mass deviation and destroying dynamic balance during high-speed rotation, and prevent impurities from scratching the inner wall of the cooling oil passage. The compressed air drying process can ensure the dryness of the inner cavity of the rotating shaft. The selection of ceramic coating and Ni-based alloy powder can specifically improve the wear resistance of the outer surface of the rotating shaft and the welded joint, and prolong the service life.

[0036] Step 6: First, fix the cleaned rotating shaft on the rotating workbench of the atmospheric plasma spraying equipment, adjust the workbench speed to 60 revolutions per minute to ensure uniform spraying. Select ceramic powder with a mass ratio of Al2O3 and TiO2 of 90:10. The ceramic coating with this ratio has high hardness and good toughness, avoiding the problem of excessive brittleness of single Al2O3 coating which is easy to peel off. Set the spraying power to 40 kW, the spraying distance to 120 mm, and the spraying speed to 50 mm / s. Start the equipment to fully spray the outer surface of the rotating shaft. Monitor the thickness in real time during the spraying process to ensure that the ceramic coating thickness is controlled within 50-100 μm.

[0037] Then, transfer the sprayed rotating shaft to the working area of the semiconductor laser cladding machine, fix it, and adjust the focal length of the laser head. Select Ni60A alloy powder with a particle size of 50-100 μm. This powder has good flowability and high bonding strength with the substrate, which can improve the wear resistance and fatigue resistance of the welded joint. Set the laser power to 3 kW, the scanning speed to 5 mm / s, and the powder feeding amount to 20 g / min. Start the cladding machine to cladding each welded joint. Monitor the molten pool temperature with an infrared thermometer during the cladding process to control it within the range of 1500-1600 ℃, ensuring metallurgical bonding between the cladding layer and the substrate. Finally, the cladding layer thickness is controlled within 150-200 μm.

[0038] After the cladding is completed, the rotating shaft is clamped on a surface grinder, and a diamond grinding wheel is selected. The Ni-based alloy cladding layer is finely ground at a grinding speed of 25 meters per second and a feed rate of 0.005 mm per revolution. After fine grinding, a surface roughness tester is used to ensure that the surface roughness Ra of the cladding layer is ≤1.6μm, so as to avoid the rough surface from increasing the frictional resistance during operation.

[0039] In this solution, the high hardness (≥HV1200) of the outer surface ceramic coating can significantly improve the overall wear resistance, and the Ni-based alloy cladding layer at the welded joint can specifically strengthen weak parts. The two strengthening methods are designed differently to take into account both the overall wear resistance and local toughness requirements. Precise spraying and cladding parameter control can ensure that the coating is firmly bonded and uniform in thickness. Fine grinding can optimize the surface quality and improve the fitting accuracy of the rotating shaft and other components.

[0040] Step 7: First, re-clamp the surface-hardened rotary shaft onto the hard-bearing dynamic balancing machine, using the same clamping method as in Step 4, to ensure clamping accuracy and avoid distortion of test results due to clamping deviations. Following the testing standards of Step 4, set the testing speed to 1.2 times the rated operating speed of the rotary shaft, and the testing accuracy class to G1.0. Start the dynamic balancing machine for testing, focusing on identifying any balance deviations that may have been introduced during the surface hardening process.

[0041] When the detected imbalance is greater than 2 g·mm / kg, a laser marking machine is used for micro-weight removal. The laser marking machine is fiber optic type with high-precision positioning function. First, according to the imbalance position displayed by the dynamic balancing machine, a mark is made on the non-fitting area of ​​the end face of the shaft. The parameters of spot diameter ≤ 2 mm and depth ≤ 1 mm are set to control the weight removed in a single operation to not exceed 0.5 g, so as to avoid damaging the surface ceramic coating or weakening the strength of the end shaft due to excessive weight removal.

[0042] After the weight reduction is completed, the rotating shaft is clamped again for testing. The micro-weight reduction-testing process is repeated until the final imbalance of the rotating shaft is ≤2g·mm / kg. The secondary dynamic balancing correction is then completed, and a high-speed motor rotating shaft that meets the requirements is obtained.

[0043] In this solution, the secondary dynamic balancing correction addresses potential imbalance deviations after surface strengthening by employing laser marking for micro-weight reduction. This method can accurately correct imbalances without damaging the surface coating, ensuring that the final imbalance meets the standard. The two dynamic balancing corrections form a closed-loop control, completely eliminating imbalance factors introduced during each stage of processing, maximizing the stability of the rotating shaft during high-speed operation, and reducing vibration and bearing wear.

[0044] A high-speed motor rotating shaft that balances dynamic balance and wear resistance, such as Figure 2As shown, it comprises a first end shaft, a middle shaft and a second end shaft; the middle shaft is a tubular structure, the side wall of the middle shaft is provided with an oil outlet hole, and a tubular cavity is formed in the middle shaft; the first end shaft is provided with an oil inlet hole in the axial direction, and the oil inlet hole is in communication with the tubular cavity of the middle shaft; the first end shaft, the middle shaft and the second end shaft are connected in sequence; the connection between the first end shaft and the middle shaft and the connection between the second end shaft and the middle shaft form welded joints, and each welded joint is provided with a Ni-based alloy cladding layer; and the outer surface of the rotating shaft is integrally provided with an Al2O3-TiO2 ceramic coating.

[0045] Advantages

[0046] The present application has the following advantages:

[0047] (1) A high-speed motor rotating shaft considering dynamic balance and wear resistance and a processing method thereof, by setting the middle shaft double-end guide sleeve positioning deep hole drilling, ultrasonic vibration deburring and external circle fine grinding combined processing technology, the problems of large straightness deviation of middle shaft inner hole, burr residue and outer circle roundness exceeding standard are avoided, laying a high-precision foundation for subsequent assembly and dynamic balance, significantly reducing the centrifugal force deviation at high speed.

[0048] (2) A high-speed motor rotating shaft considering dynamic balance and wear resistance and a processing method thereof, by setting the double-stage balance control process of post-welding initial dynamic balance correction and post-surface strengthening secondary dynamic balance correction, the problems of balance deviation introduced by welding deformation and surface strengthening and single correction cannot completely eliminate the unbalance are avoided, so that the final unbalance of the rotating shaft is stably controlled at ≤2g·mm / kg, the shaking amplitude during high-speed operation is greatly reduced, and the bearing wear and motor noise are reduced.

[0049] (3) A high-speed motor rotating shaft considering dynamic balance and wear resistance and a processing method thereof, by setting the combined process of pulse laser multi-layer multi-pass welding and customized post-welding stress relief heat treatment, the problems of large heat input, wide heat affected zone, serious welding deformation and internal stress concentration of traditional continuous welding are avoided, so that the internal stress in the welding area is reduced to ≤80MPa, the deformation is ≤0.003mm, the connection strength and structural stability of the end shaft and the middle shaft are improved, and the brittle cracking of the welding position is effectively prevented.

[0050] (4) A high-speed motor rotating shaft considering dynamic balance and wear resistance and a processing method thereof, by setting the differential surface strengthening scheme of rotating shaft outer surface ceramic coating spraying and Ni-based alloy cladding at the welded joint, the problems of friction and wear of the rotating shaft outer surface and the bearing and the sealing element and the easy wear and failure of the welded joint as a weak position are avoided, the wear resistance of the outer surface is improved by more than 3 times, the service life of the welded joint is prolonged by 2.8 times, and the overall service life of the rotating shaft is significantly prolonged.

[0051] (5) A high-speed motor rotating shaft that takes into account dynamic balance and wear resistance and a processing method thereof, through setting a deep cleaning process of high-pressure kerosene flushing and ultrasonic cleaning coordination, avoiding the problems of welding gap and internal cavity residual welding slag, metal debris and other small impurities, preventing impurities from forming local quality deviation to damage dynamic balance, while avoiding impurities scratching the inner wall of the cooling oil passage, ensuring smooth cooling oil circulation, and improving the motor cooling effect.

[0052] (6) A high-speed motor rotating shaft that takes into account dynamic balance and wear resistance and a processing method thereof, through adopting high-precision machining process of end shaft high-speed precision turning, diamond reamer reaming oil inlet hole and matching surface precision turning, avoiding the problems of end shaft outer circle cylindricity deviation, oil inlet hole inner wall roughness and matching surface perpendicularity exceeding the standard, making the end shaft and the middle shaft matching gap controlled at 0.01-0.02mm, reducing stress concentration after assembly, and improving the overall transmission efficiency and operation reliability of the rotating shaft.

[0053] Of course, implementing any product of the present application does not necessarily require all the advantages described above to be achieved at the same time. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 A flowchart of the processing method of the high-speed motor rotating shaft that takes into account dynamic balance and wear resistance of the present application;

[0055] Figure 2 A structure diagram of the high-speed motor rotating shaft that takes into account dynamic balance and wear resistance of the present application.

[0056] In the figure: 1, first end shaft; 2, middle shaft; 3, second end shaft. DETAILED DESCRIPTION

[0057] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0058] Example 1

[0059] The middle shaft is processed: select the outer diameter of 50 mm inner diameter of 30 mm 45 seamless steel tube, according to the quenching temperature 840 ℃, 1.5 hours after water quenching, tempering temperature 580 ℃, 2 hours after air cooling to get the hardness of 220 HB middle shaft blank. The middle shaft blank is fixed in the deep hole drilling bed double end guide sleeve tooling, according to the drilling speed 80 meters per minute, the feed 0.15 millimeter per turn drilling. After drilling, use laser diameter measuring instrument along the inner hole axis, select 5 detection points, confirm straightness ≤0.005 mm, according to the ultrasonic frequency 28 kHz, deburring time 3 minutes, ultrasonic vibration deburring. Finally, use centerless grinding machine, select white corundum grinding wheel grain 80#, according to the grinding speed 30 meters per second, the feed 0.01 millimeter per turn fine grinding, fine grinding detection outer roundness ≤0.003 mm, coaxiality ≤0.004 mm, transfer to the assembly station.

[0060] The end shaft is processed: select the diameter of 80 mm 40Cr alloy steel round steel, according to the temperature 860 ℃, 2 hours after furnace cooling to 300 ℃, then air cooling to normalizing treatment. The end shaft blank is clamped in the numerical control lathe three jaw chuck, select PCBN cutter type CNMG120408, according to the cutting speed 200 meters per minute, the feed 0.08 millimeter per turn turning outer surface, detection surface roughness Ra≤0.4 μm. When drilling axial oil hole, use diameter 10 mm high speed steel twist drill with guide sleeve drilling, then use H7 grade diamond reamer, according to the reaming speed 15 meters per minute, the feed 0.1 millimeter per turn reaming, hole wall roughness Ra≤0.8 μm. Use forming turning tool to process 1×45° orifice chamfer, according to the cutting speed 150 meters per minute, the feed 0.05 millimeter per turn turning matching surface, detection perpendicularity ≤0.002 mm, matching gap 0.01 mm.

[0061] Assembly welding and stress relief treatment: select three jaw centering positioning tooling, confirm tooling coaxiality error ≤0.002 mm, put the first end shaft, middle shaft, second end shaft into and correct in turn, axis deviation ≤0.003 mm. Use fiber laser welding machine, according to the pulse laser power 1.2 kW, welding speed 3 millimeter per second, pulse frequency 50 hertz, flow in 15 liters per minute argon, complete multi layer multi pass welding according to the thickness of each layer 0.8 millimeter. Put the rotating shaft into the box type resistance furnace, according to the temperature rising 5 ℃ per minute to 280 ℃, 1.5 hours, then cool to room temperature according to the cooling rate 2 ℃ per minute, detection stress in the welding area ≤80 MPa.

[0062] Initial dynamic balance correction: the rotating shaft is clamped in the hard support dynamic balancing machine, according to the rated working speed 1.2 times, G1.0 level precision detection, when the unbalance is greater than 2 g·mm / kg, mark on the end surface of the end shaft, drill hole weight loss by electric spark processing, the number of single drilling is not more than 3, the final unbalance is less than or equal to 2 g·mm / kg.

[0063] Cleaning process: high pressure kerosene flushing pressure 15 MPa, time 5 minutes, slowly rotating the rotating shaft during flushing. Configure the mixed cleaning solution of kerosene plus 5% cleaning agent, put the rotating shaft into the ultrasonic cleaning tank, clean according to the frequency of 40 kHz, time of 10 minutes, turn over every 2 minutes. Blow dry with compressed air of pressure 0.6 MPa, dew point ≤-40℃ for 3 minutes, detect no water residue.

[0064] Surface strengthening treatment: fix the rotating shaft on the rotating workbench of the atmospheric plasma spraying equipment, rotating speed 60 revolutions per minute, select ceramic powder with mass ratio of Al2O3 to TiO2 90:10, spray according to the spraying power 40 kW, spraying distance 120 mm, spraying speed 50 mm per second, coating thickness 50 μm. Transfer to the semiconductor laser cladding machine, select Ni60A alloy powder with particle size 50 μm, according to the laser power 3 kW, scanning speed 5 mm per second, powder feeding amount 20 g / min, cladding on the welded joint, cladding layer thickness 150 μm. Use the surface grinder to fine grind the cladding layer according to the grinding speed 25 meters per second, feed amount 0.005 mm per revolution, detect the surface roughness Ra ≤1.6 μm.

[0065] Second dynamic balance correction: detect again according to the detection standard of step 4, when the unbalance is >2 g·mm / kg, use the fiber laser marking machine to remove a small amount of weight on the end face of the end shaft in the non-matching area, spot diameter ≤2 mm, depth ≤1 mm, single removal weight not more than 0.5 g, final unbalance ≤2 g·mm / kg.

[0066] Example 2

[0067] Middle shaft processing: same as example one, only drilling speed is 120 meters per minute, ultrasonic vibration deburring time is 5 minutes, and the hardness after quenching and tempering treatment is 250 HB.

[0068] End shaft processing: same as example one, only the matching gap is controlled to be 0.02 mm.

[0069] Assembly welding and stress relief treatment: same as example one, only the pulse laser power is 1.8 kW, the welding speed is 5 mm per second, the pulse frequency is 80 Hz, the welding thickness of each layer is 1.2 mm, the stress relief heat treatment temperature is 320℃, and the holding time is 2 hours.

[0070] First dynamic balance correction: same as example one, only the electric spark machining drilling diameter is 4 mm, and the depth is 5 mm.

[0071] Cleaning process: same as example one, only the high pressure kerosene flushing pressure is 20 MPa.

[0072] Surface strengthening treatment: same as example one, only ceramic coating thickness 100 μm, Ni60A alloy powder particle size 100 μm, cladding layer thickness 200 μm.

[0073] Secondary dynamic balance correction: same as example one.

[0074] Comparative example 1

[0075] Middle shaft processing: select the same 45 seamless steel pipe as example one, without quenching and tempering treatment, directly drill with ordinary drill without guide sleeve, mechanical scraper deburring, ordinary cylindrical grinder fine grinding, without setting stage detection, only final detection of inner hole straightness ≤0.015 mm, outer circle roundness ≤0.01 mm.

[0076] End shaft processing: select the same 40Cr alloy steel round steel as example one, without normalizing treatment, ordinary lathe turning outer surface, surface roughness Ra≤1.6 μm. Oil inlet hole is only drilled with twist drill, without reaming, hole wall roughness Ra≤2.0 μm, hole without chamfer, fit surface perpendicularity ≤0.008 mm, fit clearance 0.03-0.05 mm.

[0077] Assembly welding and stress relief treatment: ordinary positioning tool assembly, axis deviation ≤0.01 mm. Adopt continuous laser welding, without protective gas, without post-welding stress relief heat treatment, stress in welding area >300 MPa.

[0078] Dynamic balance treatment: without special dynamic balance correction, only rely on natural balance state after processing.

[0079] Cleaning process: only 10 MPa high pressure oil flushing for 5 minutes, without ultrasonic cleaning and drying treatment.

[0080] Surface strengthening treatment: without any surface strengthening treatment.

[0081] Comparative example 2

[0082] Middle shaft processing: same as example one.

[0083] End shaft processing: same as example one.

[0084] Assembly welding and stress relief treatment: same as example one.

[0085] Dynamic balance treatment: only one dynamic balance correction (consistent with the initial dynamic balance of example one), without secondary dynamic balance correction.

[0086] Cleaning process: same as example one.

[0087] Surface strengthening treatment: only the outer surface of the rotating shaft is sprayed with a ceramic coating (the same parameters as in Example 1), and the welding joint is not subjected to Ni-based alloy cladding.

[0088] Experimental Example 1

[0089] Experimental design: set up experimental groups (Example 1, Example 2) and control groups (Comparative Example 1, Comparative Example 2), and select 3 samples from each group, focusing on verifying the innovative effect of the two-stage dynamic balance correction. Among them, the experimental group adopts the closed-loop process of the first dynamic balance after welding and the second dynamic balance after surface strengthening, Comparative Example 1 does not adopt any special dynamic balance correction process and lacks multiple key links such as conditioning treatment, precision machining, etc., and Comparative Example 2 only adopts single dynamic balance correction. Test the initial unbalance, unbalance after running for 1000 hours, running vibration amplitude and bearing wear depth of the rotating shaft at the rated working speed of 30000r / min.

[0090] Experimental process: install the samples in each group on the high-speed motor test bench, and run continuously at the rated speed for 1000 hours. During the running, the unbalance change is detected every 200 hours, the vibration amplitude is monitored in real time through the vibration sensor, and the bearing wear depth is measured by a high-precision thickness gauge after the experiment.

[0091] Group Initial unbalance (g-mm / kg) Unbalance after 1000 hours of operation (g-mm / kg) Operation run-out amplitude (mm) Bearing wear depth (mm) Example 1 ≤2.0 ≤2.1 ≤0.02 ≤0.01 Example 2 ≤2.0 ≤2.2 ≤0.02 ≤0.01 Comparative Example 2 ≤2.0 ≥3.5 ≥0.05 ≥0.03 Comparative Example 1 ≥5.0 ≥8.0 ≥0.10 ≥0.08

[0092] Experimental results: the unbalance of the experimental group is stably controlled at ≤2.2g·mm / kg, the running vibration amplitude is ≤0.02mm, and the bearing wear depth is ≤0.01mm, whether initially or after long-term running; the unbalance of Comparative Example 2 soared to ≥3.5g·mm / kg after long-term running, and the vibration amplitude and bearing wear were both more than 2 times of the experimental group; the initial unbalance of Comparative Example 1 was far beyond the standard due to the lack of any dynamic balance correction and the extensive process, and the performance deteriorated more seriously after long-term running, with the vibration amplitude being 5 times of the experimental group and the bearing wear depth being 8 times of the experimental group.

[0093] Experimental conclusion: the two-stage dynamic balance correction process can accurately offset the balance deviation introduced by processes such as welding deformation and surface strengthening, ensuring the stability of the balance accuracy of the rotating shaft during long-term running. Compared with the process of only single dynamic balance or no dynamic balance, this scheme can significantly reduce the vibration amplitude and bearing wear during high-speed running. Even compared with the traditional scheme with multiple process defects, it can still achieve a leap-forward improvement in balance performance and running stability, fully verifying the core value of this innovative link.

[0094] Experimental Example 2

[0095] Experimental design: set the experimental group (example one, example two) and the control group (comparative example one, comparative example two), each group selects 3 samples, specially verifies the innovative effect of the differential surface strengthening design. Among them, the experimental group adopts the combination scheme of the outer surface Al2O3-TiO2 ceramic coating and the welding joint Ni-based alloy cladding, comparative example one does not carry out any surface strengthening treatment, comparative example two only sprays ceramic coating on the outer surface. The friction and wear tester is used to test the wear resistance of the outer surface of the rotating shaft, and the fatigue tester is used to test the fatigue life of the welding joint.

[0096] Experimental process: the friction and wear test adopts the pin-disk friction mode, sets the load to 50N, the rotating speed to 500r / min, and tests the outer surface wear after 10000 cycles; the welding joint fatigue test is carried out according to the parameters of axial load ±300MPa and frequency 10Hz, and the test is continuously carried out until the joint is broken, and the cycle number at the time of breaking is recorded.

[0097] Group Outer surface wear (mm) Welded joint fatigue cycle number (times) Example 1 ≤0.005 ≥ 1.2 x 10 6 ]] Example 2 ≤0.005 ≥ 1.2 x 10 6 ]] Comparative Example 2 ≤0.006 ≥ 0.6 x 10 6 ]] Comparative Example 1 ≥0.020 ≥ 0.3 x 10 6 ]]

[0098] Experimental results: the outer surface wear of the experimental group is only ≤0.005mm, and the fatigue cycle number of the welding joint is ≥1.2×10 6 times; comparative example two has no Ni-based alloy cladding strengthening of the welding joint, although the outer surface wear is close to that of the experimental group, but the fatigue resistance of the welding joint is greatly reduced, and the fatigue cycle number is only 50% of that of the experimental group; comparative example one has no any surface strengthening, the outer surface wear is 4 times that of the experimental group, and the fatigue cycle number of the welding joint is only 25% of that of the experimental group.

[0099] Experimental conclusion: the differential surface strengthening design realizes the precise matching of the overall wear resistance and the local toughness, the ceramic coating on the outer surface can ensure the overall high wear resistance, and the Ni-based alloy cladding layer at the welding joint can specifically improve the fatigue resistance and wear resistance of this weak part. Compared with single coating design or non-strengthening design, this scheme not only solves the overall wear problem of the rotating shaft, but also makes up for the performance short board of the welding joint, so that the wear resistance and structural stability are improved, and the practicability and advancement of the innovative link are fully verified.

[0100] It should be noted that in this paper, relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment.

[0101] The preferred embodiments of the application disclosed above are only to help explain the present application. The preferred embodiments are not intended to be exhaustive or to limit the application to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the application be limited not with this detailed description, but rather by the claims and the full range of equivalents that are claimed.

Claims

1. A method for machining a high-speed motor rotating shaft that balances dynamic balance and wear resistance, comprising a first end shaft, a middle shaft, and a second end shaft, characterized in that, Includes the following steps: Step 1: The tubular structure shaft is machined using a combination of double-ended guide sleeve positioning and deep hole drilling, ultrasonic vibration deburring, and outer diameter precision grinding to obtain a shaft with inner hole straightness ≤0.005mm, outer diameter roundness ≤0.003mm, and coaxiality ≤0.004mm. The raw material for the central shaft is 45 seamless steel pipe. Before processing, it is quenched and tempered at a quenching temperature of 840℃ and a tempering temperature of 580℃ to obtain a central shaft blank with a hardness of 220-250HB. The deep hole drilling speed is 80-120 meters per minute and the feed rate is 0.15 mm per revolution. The ultrasonic vibration deburring frequency is 28 kHz and the time is 3-5 minutes. The outer cylindrical precision grinding is carried out using a centerless grinder with a grinding speed of 30 meters per second and a feed rate of 0.01 mm per revolution. Step 2: The end shaft is machined using a combination of high-speed precision turning, diamond reaming, and precision turning of the mating surfaces. An axial oil inlet hole is made on one of the end shafts and chamfered to obtain an end shaft with an outer circle cylindricity ≤0.002mm and a mating surface perpendicularity ≤0.002mm. The end shaft is made of 40Cr alloy steel. Before machining, it is normalized at a temperature of 860℃ and a holding time of 2 hours. High-speed precision turning is performed using PCBN tools with a cutting speed of 200 meters per minute and a feed rate of 0.08 mm per revolution. The surface roughness Ra after turning is ≤0.4μm. The axial oil inlet hole is drilled with a 10mm diameter twist drill and then reamed with an H7 grade diamond reamer at a reaming speed of 15 meters per minute and a feed rate of 0.1 mm per revolution. The hole wall roughness Ra≤0.8μm; the hole opening chamfer is 1×45°, and the clearance between the end shaft and the central shaft is 0.01-0.02mm. Step 3: After coaxially fixing the first end shaft, the middle shaft, and the second end shaft, connect them using a pulsed laser multi-layer multi-pass welding process and perform post-weld stress relief heat treatment to obtain an integral rotating shaft with a welding internal stress ≤80MPa and a deformation ≤0.003mm. The components are fixed by a three-jaw centering and positioning fixture. The coaxiality error of the fixture is ≤0.002mm, and the axial deviation after assembly is ≤0.003mm. The pulsed laser welding power is 1.2-1.8 kW, the speed is 3-5 mm / s, the pulse frequency is 50-80 Hz, the shielding gas is argon, the flow rate is 15 liters per minute, and the thickness of each weld layer is 0.8-1.2 mm. Step 4: Use a hard-support dynamic balancing machine to perform dynamic balancing test on the entire rotating shaft. For rotating shafts with excessive imbalance, use electrical discharge machining to drill holes to remove weight, so that the imbalance of the rotating shaft is ≤2g·mm / kg. Step 5: Clean the inner cavity of the rotating shaft and weld seams using a combination of high-pressure kerosene flushing and ultrasonic cleaning to remove residual impurities; High-pressure kerosene is used at a pressure of 15-20 MPa for 5 minutes, during which the rotating shaft is rotated slowly. The ultrasonic cleaning fluid is a mixture of kerosene and 5% cleaning agent, with a frequency of 40 kHz and a cleaning time of 10 minutes. During the cleaning process, the rotating shaft is rotated every 2 minutes. After cleaning, it is dried with compressed air at a pressure of 0.6 MPa and a dew point ≤ -40℃ for 3 minutes. Step 6: Spray a ceramic coating onto the outer surface of the rotating shaft, clad the welded joint with a Ni-based alloy coating and finely grind it to achieve differentiated surface strengthening; The ceramic coating is an Al2O3-TiO2 coating with an Al2O3 to TiO2 mass ratio of 90:10, a thickness of 50-100μm, and a hardness ≥HV1200; the Ni-based alloy coating uses Ni60A alloy powder with a particle size of 50-100μm, a cladding thickness of 150-200μm, and a surface roughness Ra≤1.6μm after fine grinding. Step 7: Use a hard-bearing dynamic balancing machine to test again. For the rotating shaft with excessive imbalance, use laser marking to remove a small amount of weight, and finally obtain a high-speed motor rotating shaft with an imbalance of ≤2g·mm / kg. Laser marking for micro-weight removal: the diameter of the spot is ≤2 mm and the depth is ≤1 mm, the weight removed in a single operation is no more than 0.5 g, and the weight removal area is the non-contact area of ​​the end face of the shaft.

2. The high-speed motor rotary shaft machining method according to claim 1, which takes into account both dynamic balance and wear resistance, is characterized in that: In step 1, after drilling, a laser diameter gauge is used to check the straightness of the inner hole. After fine grinding, a roundness tester and a coaxiality tester are used to check the roundness and coaxiality of the outer circle, respectively. After confirming that the standard is met, the process proceeds to the next step.

3. The high-speed motor rotary shaft machining method according to claim 1, which combines dynamic balance and wear resistance, is characterized in that: In step 3, the stress relief heat treatment is performed using a box-type resistance furnace with a heating rate of 5°C per minute. After heating to 280-320°C, the temperature is held for 1.5-2 hours, and the cooling rate is 2°C per minute, cooling the furnace to room temperature.

4. The high-speed motor rotary shaft machining method according to claim 1, which takes into account both dynamic balance and wear resistance, is characterized in that: In step 4, the dynamic balancing test speed is 1.2 times the rated working speed of the rotating shaft, and the test accuracy level is G1.

0. The diameter of the electrical discharge machining (EDM) hole is 2-4 mm and the depth is 3-5 mm. The distance between the hole position and the center axis of the end shaft is not less than 1 / 3 of the radius of the end shaft, and the number of holes drilled at one time does not exceed 3.

5. A high-speed motor rotary shaft that balances dynamic balance and wear resistance, manufactured using the high-speed motor rotary shaft processing method that balances dynamic balance and wear resistance as described in any one of claims 1-4, characterized in that, It includes a first end shaft (1), a middle shaft (2), and a second end shaft (3); the middle shaft (2) is a tubular structure, with an oil outlet hole on the side wall of the middle shaft (2) and a tubular cavity inside the middle shaft (2); the first end shaft (1) has an oil inlet hole along the axial direction, and the oil inlet hole is connected to the tubular cavity of the middle shaft (2); the first end shaft (1), the middle shaft (2), and the second end shaft (3) are connected in sequence.

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