A cage type aluminum rotor defect detection device and method

Abstract

The application discloses a cage type cast aluminum rotor defect detection device and method, and belongs to the cast aluminum rotor defect detection field, including a test table, a magnetic field generating unit, a rotor clamp unit, a defect monitoring device and a constant temperature control system are arranged on the test table; the principle of locked-rotor experiment is used to detect the cast aluminum rotor bar defects, the stator winding temperature is monitored in real time through the constant temperature control unit temperature sensor, when the temperature exceeds the preset threshold value, the cooling assembly is started, the temperature is stabilized in the target range, the winding resistance is maintained constant, the current change is ensured to be caused by the rotor defect, not the temperature fluctuation, thereby the detection accuracy is improved, in the batch detection of the rotor assembly line, if the temperature is not controlled, continuous detection of multiple rotors can cause the winding temperature to gradually increase, the resistance change accumulates, and finally the current reference deviates from the initial value. The constant temperature control unit itself ensures that the detection environment of each rotor is consistent through real-time cooling, and accumulation error is avoided.

Description

A cage-type cast aluminum rotor defect detection device and method Technical Field

[0001] This application belongs to the field of defect detection of cast aluminum rotors, and particularly relates to a cage-type cast aluminum rotor defect detection device and method. Background Technology

[0002] The cast aluminum rotor of an AC asynchronous motor is generally a squirrel-cage type. The common casting method typically includes the following steps: Thin silicon steel sheets are stacked and pressed into a cylindrical iron core. Numerous slots are formed on the iron core, and a temporary shaft (dummy shaft) is inserted in the middle to fix its position. The stacked iron core is placed in a heating furnace, and aluminum blocks (ingots) are placed in the furnace and heated. The molten aluminum is then "pressed" into the iron core slots using pressure. After pouring the molten aluminum, the rotor is allowed to cool slowly in the mold before being removed. Defects often occur in the cast aluminum rotor, such as broken strips, thin strips, cracks, shrinkage cavities, air holes, and incomplete casting (including voids in the end rings, and uneven fan blades or balance columns). These defects reduce motor performance, increase temperature, and increase slip. Therefore, it is essential to inspect the cast aluminum rotor for defects.

[0003] One existing method for detecting defects in cast aluminum rotors is motor stall detection. This method involves keeping the rotor stationary while applying a rotating magnetic field to detect defects. When the rotor is stationary but a rotating magnetic field is applied, the stator windings will generate current, attempting to drive the rotor to rotate. If the rotor is intact: the conductor bars (the conductive strips in the rotor) will uniformly cut the magnetic lines of force, forming a stable induced current. The motor current will briefly increase and then stabilize at a certain value (because the back electromotive force is zero, the current is larger than during normal operation, but it will not increase indefinitely). If the rotor has defects (such as broken conductor bars or pores): broken conductor bars will cause the current path to be interrupted, and some areas will not be able to form an induced current. The motor will need a larger current to maintain the magnetic field, resulting in an abnormally high total current. Pores or shrinkage cavities will reduce the effective conductive area of ​​the conductor bars, also requiring a larger current to compensate, and may cause localized overheating.

[0004] However, during stall testing, the motor windings generate a large amount of heat due to the high current. The increased temperature changes the resistance of the motor windings, causing it to increase. With the voltage remaining constant, the current will decrease, which may lead to a misjudgment that the rotor is defect-free, resulting in errors.

[0005] Locked rotor detection assesses rotor quality based on current magnitude and three-phase balance. However, end ring defects (such as cracks and unevenness) have a relatively small direct impact on conductor current, making them undetectable by the detection equipment. Therefore, there is an urgent need to develop a dynamic rotor defect compensation device and method that balances detection efficiency and accuracy to solve the problem of consistent detection for cast aluminum rotors. This demonstrates that existing technologies require further improvement and enhancement. Summary of the Invention

[0006] The present invention provides a cage-type cast aluminum rotor defect detection device and method to at least solve or alleviate one or more technical problems in the prior art, or at least provide a beneficial alternative.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A cage-type cast aluminum rotor defect detection device includes a test bench, on which a magnetic field generating unit, a rotor clamping unit, a defect monitoring device, and a constant temperature control system are provided.

[0009] The magnetic field generating unit includes a stator winding and a constant voltage power supply, which is used to generate a rotation detection magnetic field. The center of the stator winding is provided with a cavity for placing the rotor.

[0010] The rotor clamping unit is located above and below the detection area of ​​the magnetic field generating unit. It includes an axial clamping mechanism to fix the rotor to be inspected and ensure that the rotor axis coincides with the stator winding axis.

[0011] The defect monitoring device is electrically connected to the magnetic field generating unit to collect electrical parameters and identify the defect characteristics of the rotor bars;

[0012] The constant temperature control unit includes a temperature sensor and a cooling component. The temperature sensor monitors the operating temperature of the magnetic field generating unit in real time. When the temperature exceeds a preset threshold, the cooling component is triggered to maintain the magnetic field generating unit within the target detection temperature range to ensure test consistency.

[0013] In a preferred embodiment, the cooling assembly includes a cooling shroud disposed on the outer periphery of the stator winding. The cooling shroud has an inlet and an outlet, as well as a spiral flow channel connecting the inlet and the outlet. The inlet is connected to the outlet of the heat exchanger through a first pipe, and the outlet is connected to the inlet of the heat exchanger through a second pipe.

[0014] In a preferred embodiment, the axial clamping mechanism includes a bearing component and a clamping component. The bearing component is located directly below the cavity and has a lifting function. The clamping component is located on one side of the magnetic field generating unit, can rotate to the upper side of the cavity, and also has a lifting function. Both the bearing component and the clamping component are provided with a shaft-shaped structure that adapts to the rotor's central hole, and a limiting part is provided below the shaft-shaped structure. The shaft-shaped structure can pass into the rotor shaft hole, and the limiting part abuts against the flat end face of the rotor.

[0015] In a preferred embodiment, the bearing assembly includes a support frame, which is fixed to the lower side of the test bench. A bearing seat is provided on the upper side of the support frame. The end face of the bearing seat is provided with a shaft-like structure and a limiting part. The diameter of the bearing seat is adapted to the diameter of the rotor. A first lifting cylinder is provided on the lower side of the support frame. The piston rod of the first lifting cylinder passes through the support frame and connects to the bearing seat.

[0016] The clamping assembly includes a rotating motor disposed below the test bench. The output shaft of the rotating motor passes through the test bench surface and is connected to a rotating arm. The rotating arm is equipped with a second lifting cylinder, which is connected to a clamping seat. The end face of the clamping seat is provided with the shaft-shaped structure and the limiting part.

[0017] In a preferred embodiment, the rotating arm includes a vertical beam connected to a rotating motor, and a first and second horizontal beam with a designed angle between their ends. The second lifting cylinder is mounted on the first horizontal beam, and a third lifting cylinder is mounted on the second horizontal beam. The piston rod end of the third lifting cylinder is rotatably connected to a conductive component. One side of the conductive component can contact the end ring of the rotor, and the other side is provided with a stationary brush. The bearing seat is rotatably connected to the end of the piston rod of the first lifting cylinder. When the rotor rotates, it drives the bearing seat and the conductive component to rotate synchronously. The brush contacts different parts of the conductive component. The brush is connected to a current detection device to collect current parameters to determine end ring defects.

[0018] In a preferred embodiment, the shape of the contact surface of the conductive element is adapted to the surface profile of the rotor end ring; the contact surface is provided with a clearance structure to accommodate the balance column or fan blade on the surface of the end ring, so that the conductive element is in close contact with the end ring.

[0019] In a preferred embodiment, the conductive component is a copper plate ring, and an insulating bearing is provided on the outer side of the piston rod end of the third lifting cylinder, with the copper plate ring rotatably connected to the insulating bearing.

[0020] In a preferred embodiment, the brush is fixed to the piston rod of the third lifting cylinder by a bracket and is located on the upper side of the conductive element.

[0021] In a preferred implementation, a control system is also included, which is electrically connected to the magnetic field generating unit, the rotor clamping unit, and the constant temperature control unit to intelligently control the operation of each unit.

[0022] The detection method of the cage-type cast aluminum rotor defect detection device includes the following steps:

[0023] S1: Deshelling treatment of cast aluminum rotor

[0024] The rotors on the cast aluminum rotor production line are transferred from the conveyor belt to the rotor outer circle cleaning machine by the first robot arm. Utilizing the residual heat of the cast aluminum rotor, the outer circle of the rotor is cleaned by a flexible scraper or wire wheel to remove aluminum chips and impurities. During the chip removal process, heat is generated by the friction between the scraper / wire wheel and the outer circle of the rotor, which raises the surface temperature of the rotor to the aluminum strip descaling process temperature. The second robot arm quickly immerses the rotor in the coolant for rapid cooling. Utilizing the difference in thermal expansion coefficients between aluminum and silicon steel sheets, a gap is created between the aluminum strips and silicon steel sheets to complete the descaling process.

[0025] S2: Rotor positioning

[0026] The support seat is lifted up, the piston rod of the first lifting cylinder on the test platform is lifted up, the support seat enters the cavity and protrudes from the upper surface, the end face shaft structure and the limiting part are exposed, the third robot arm aligns the center hole of the deshelled rotor with the shaft structure of the support seat to complete the mating connection, the piston rod of the first lifting cylinder descends, and the rotor is transferred to the designed position of the cavity.

[0027] S3: Rotor clamping and fixing

[0028] The rotating motor drives the second lifting cylinder to the top of the cavity. The shaft-shaped structure on the end face of the clamping seat is aligned with the center hole of the rotor. The second lifting cylinder descends, and the clamping seat and the center hole of the rotor are inserted into each other. Axial pressure is applied to ensure that the rotor does not rotate.

[0029] S4: Guide bar defect detection

[0030] The magnetic field generating unit is activated to generate a rotating magnetic field. The defect monitoring device collects the three-phase stall current of the stator winding and analyzes the three-phase balance and harmonic content. The temperature sensor monitors the temperature of the magnetic field generating unit in real time. When the temperature exceeds the limit, the cooling component is triggered to maintain the temperature range of the stator winding and prevent changes in its resistance from causing measurement errors.

[0031] S5: End-ring defect detection

[0032] If the conductor bar passes the test, first turn off the third lifting cylinder of the magnetic field generating unit and rotate it to the top of the cavity. The piston rod descends to make the conductive part make close contact with the rotor end ring. Then restart the magnetic field generating unit. The rotor rotates in the rotating magnetic field. The brush contacts the end ring and collects multiple current values ​​around one revolution. If the deviation of the multiple current values ​​is greater than the design parameters, the end ring is judged to be unqualified.

[0033] S6: Sorting and Circulation

[0034] Handling of defects: When the guide bar or end ring fails the test, the magnetic field generating unit is shut down, the second lifting cylinder rises and rotates away from the cavity, the first lifting cylinder lifts the rotor, and the robot arm transfers it to the defective work station;

[0035] Qualified transfer: When both the guide bar and the end ring pass the inspection, the rotor is lifted by the first lifting cylinder and transferred to the qualified work station by the robot.

[0036] The above structure has the following beneficial effects:

[0037] 1. The cage-type cast aluminum rotor defect detection device of this application is applied at the end of the automatic rotor cast aluminum production line to monitor the quality of cast aluminum in real time.

[0038] 2. The cage-type cast aluminum rotor defect detection device of this application monitors the stator winding temperature in real time through the temperature sensor of the constant temperature control unit. When the temperature exceeds the preset threshold, the cooling component is activated to stabilize the temperature within the target range, maintain the winding resistance constant, and ensure that the current change is caused only by rotor defects, rather than temperature fluctuations, thereby improving the detection accuracy.

[0039] 3. The cage-type cast aluminum rotor defect detection device of this application has a shaft structure diameter that matches the rotor center hole tolerance of the bearing component and the clamping component. The limiting part adopts a rigid flange design. When the shaft structure is fully inserted, the limiting surface and the rotor end face form a surface contact. The shaft hole fit eliminates tilting and ensures the uniformity of the air gap between the rotor and the stator. The lifting function ensures that the rotor is in the same position in the cavity each time, so that each rotor has a consistent posture repeatability in the cavity, which significantly reduces the electromagnetic performance fluctuation caused by assembly.

[0040] 4. The cage-type cast aluminum rotor defect detection device of this application realizes online detection of the end ring through contact-type electrical signal acquisition. The brush continuously scans the entire circumference of the end ring to avoid missing local defects. There is no need to switch detection equipment, reducing transfer procedures and eliminating the need for rotor repositioning.

[0041] 5. The detection method of the cage-type cast aluminum rotor defect detection device of this application, the solution of this application realizes full quality control of cast aluminum rotor through the process of "shell removal-positioning-pressing-guide bar detection-end ring detection-sorting", with high detection accuracy, and is suitable for efficient automated production lines. Attached Figure Description

[0042] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and, together with their description, serve to explain this application and do not constitute an undue limitation of the invention. In the drawings:

[0043] Figure 1 illustrates a schematic structural diagram of one embodiment of the cage-type cast aluminum rotor defect detection device of this application in the rotor receiving state;

[0044] Figure 2 illustrates a schematic structural diagram of one embodiment of the cage-type cast aluminum rotor defect detection device of this application, in which the rotor is mounted on a bearing seat.

[0045] Figure 3 illustrates a schematic structural diagram of one embodiment of the cage-type cast aluminum rotor defect detection device of this application, in which the rotor is transferred to the cavity;

[0046] Figure 4 illustrates a schematic structural diagram of one embodiment of the clamping assembly of the cage-type cast aluminum rotor defect detection device of this application clamping the rotor;

[0047] Figure 5 illustrates a schematic structural diagram of one embodiment of the cage-type cast aluminum rotor defect detection device of this application, showing the conductive component pressing the rotor end ring.

[0048] Figure 6 illustrates a schematic structural diagram of one embodiment of the cage-type cast aluminum rotor defect detection device of this application, in which the clamping component or conductive element is removed from the cavity after the guide bar detection or end ring detection is completed.

[0049] Figure 7 illustrates a schematic structural diagram of one embodiment of the cage-type cast aluminum rotor defect detection device of this application, in which the rotor is moved out of the cavity;

[0050] Figure 8 illustrates a schematic flow view of one embodiment of the cage-type cast aluminum rotor defect detection device of this application located at the end of the cast aluminum rotor production line;

[0051] Figure 9 illustrates a schematic embodiment of rotor descrambling according to this application;

[0052] Label Explanation:

[0053] 1. Test bench; 20. Stator winding; 21. Cavity; 30. Bearing assembly; 300. Support frame; 301. Bearing seat; 3010. Shaft structure; 3011. Limiting part; 302. First lifting cylinder; 310. Rotating motor; 311. Rotating arm; 312. Second lifting cylinder; 313. Pressing seat; 314. Third lifting cylinder; 315. Conductive component; 316. Brush; 40. Display; 41. Control system; 50. Cooling cover; 501. Spiral flow channel; 51. Heat exchanger; 510. First pipeline; 511. Second pipeline; 6. Rotor; 60. End ring. Detailed Implementation

[0054] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit and scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0055] The present invention will now be described with reference to the accompanying drawings.

[0056] The specific solution adopted is as follows:

[0057] As shown in Figures 1-9, the present invention provides a cage-type cast aluminum rotor defect detection device, including a test bench 1, on which a magnetic field generating unit, a rotor clamping unit, a defect monitoring device and a constant temperature control system are provided.

[0058] The magnetic field generating unit includes a stator winding 20 and a constant voltage power supply, which is used to generate a rotation detection magnetic field. The center of the stator winding 20 is provided with a cavity 21 for placing the rotor 6.

[0059] The rotor clamping unit is located above and below the detection area of ​​the magnetic field generating unit. It includes an axial clamping mechanism for fixing the rotor 6 to be inspected and ensuring that the axis of the rotor 6 coincides with the axis of the stator winding 20.

[0060] The defect monitoring device is electrically connected to the magnetic field generating unit, collects electrical parameters, and identifies defect characteristics of the rotor's six conductor bars;

[0061] The constant temperature control unit includes a temperature sensor and a cooling component. The temperature sensor monitors the operating temperature of the magnetic field generating unit in real time. When the temperature exceeds a preset threshold, the cooling component is triggered to maintain the magnetic field generating unit within the target detection temperature range to ensure test consistency.

[0062] The principle of the locked-rotor test is to apply rated voltage or reduce voltage to the stator winding 20 while the motor rotor 6 is mechanically locked (locked), measure the locked-rotor current, locked-rotor torque, and input power, and plot the locked-rotor characteristic curve (the relationship between locked-rotor current, locked-rotor torque, and input voltage). The relevant parameters or images are displayed on the monitor 40. Its core principle is to indirectly reflect the symmetry and conductivity of the rotor 6 winding by analyzing the balance of locked-rotor current and torque.

[0063] If the rotor winding 6 is symmetrical (with uniform conductor bar resistance), the locked-rotor current will be balanced across the three phases. However, if there are broken bars, thin bars, or abnormal local resistance in the conductor bars, the current will become unbalanced. For example, a broken bar in rotor 6 will significantly reduce the locked-rotor current, and the difference between the three phase currents will exceed the standard (e.g., >5%). The locked-rotor torque is related to the resistance of rotor 6. If the resistance of rotor 6 increases (e.g., due to thin bars or pores reducing the effective conductive area), the locked-rotor torque will decrease, and the slope of the torque-voltage curve will change.

[0064] During locked-rotor testing, the stator winding 20 generates a large amount of heat due to high current (back electromotive force is zero, current can reach 5-7 times the rated value), causing the winding resistance to increase (the resistance of a copper conductor increases by about 4% when the temperature rises by 10℃). According to Ohm's law I=U / R, the increase in resistance will cause a decrease in current, which may mask the current anomaly caused by defects in rotor 6 (such as current increase caused by broken bars or porosity), leading to misjudgment.

[0065] The constant temperature control unit of this application monitors the temperature of the stator winding 20 in real time by a temperature sensor. When the temperature exceeds a preset threshold (e.g., 80°C), the cooling component is activated to stabilize the temperature within the target range (e.g., 60-70°C), maintaining the winding resistance constant and ensuring that the current change is caused only by defects in the rotor 6, rather than by temperature fluctuations, thereby improving the detection accuracy.

[0066] In batch testing on the rotor 6 production line, if the temperature is not controlled, continuous testing of multiple rotors 6 will cause the winding temperature to rise successively, resulting in accumulated resistance changes and ultimately causing the current reference to deviate from the initial value. However, its own constant temperature control unit ensures a consistent testing environment for each rotor 6 through real-time cooling, avoiding accumulated errors.

[0067] The method for measuring the temperature of the stator winding 20 is to embed a pre-manufactured copper resistance temperature sensor element between the upper and lower wire bars of the generator stator winding 20 during the generator manufacturing process. Then, it is led out from the iron core through a shielded wire and connected to a resistance thermometer for indication. Alternatively, infrared thermal imaging technology (non-contact) or a fiber optic grating temperature measurement system (anti-electromagnetic interference) can be used. Of course, other existing technologies can also be used for direct or indirect temperature measurement, which will not be elaborated here.

[0068] Referring to Figure 1, the cooling assembly adopts a closed-loop liquid cooling circulation system. The core components include a cooling shroud 50, a heat-conducting shell that surrounds the outer periphery of the stator winding 20, and an internal spiral flow channel 501 designed to enhance heat exchange efficiency. The spiral flow covers the axial direction of the stator winding 20, causing the coolant to form vortices during the flow process, breaking the thermal boundary layer and improving the convective heat transfer coefficient. The heat exchanger 51 can be a plate or shell-and-tube heat exchanger, which removes heat through a secondary cooling medium (such as cryogenic liquid or cold air).

[0069] First pipeline 510: connects the outlet of heat exchanger 51 to the inlet of cooling cover 50, and transports low-temperature coolant.

[0070] Second pipe 511: connects the outlet of cooling cover 50 to the inlet of heat exchanger 51, and returns high-temperature coolant.

[0071] Pump body configuration: Provides circulation power and maintains stable flow rate.

[0072] During locked-rotor testing, the current in stator winding 20 can reach 5-7 times the rated value. Joule heating causes the winding temperature to rise over a certain period of time. When the temperature exceeds the over-temperature value, low-temperature coolant (such as a 25°C ethylene glycol aqueous solution) enters the inlet of cooling shroud 50 from the outlet of heat exchanger 51 through the first pipe 510. It absorbs heat through forced convection heat exchange, and the heated coolant flows out from the outlet and enters heat exchanger 51 through the second pipe 511 to exchange heat with the secondary cooling medium. The coolant then cools down and re-enters the circulation to cool stator winding 20.

[0073] The cooling shroud 50 is integrated into the stator housing, requiring no additional installation space. Closed-loop control ensures temperature stability and avoids current detection errors caused by resistance changes. This achieves rapid and stable cooling of the stator winding 20 under testing conditions, providing a reliable environmental guarantee for high-precision rotor defect detection.

[0074] Referring to Figures 1-7, the axial clamping mechanism includes a bearing component 30 and a clamping component. The bearing component 30 is located directly below the cavity 21 and has a lifting function. The clamping component is located on one side of the magnetic field generating unit, can rotate to the upper side of the cavity 21, and also has a lifting function. Both the bearing component 30 and the clamping component are provided with a shaft-shaped structure 3010 that adapts to the rotor's central hole, and a limiting part 3011 is provided below the shaft-shaped structure 3010. The shaft-shaped structure 3010 can pass into the rotor shaft hole, and the limiting part 3011 abuts against the flat end face of the rotor.

[0075] The diameter of the shaft structure 3010 matches the tolerance of the rotor center hole. The limiting part 3011 adopts a rigid flange design. When the shaft structure 3010 is fully inserted, the limiting part surface and the rotor end face form a surface contact. The shaft hole fit eliminates tilting and ensures the uniformity of the air gap between the rotor 6 and the stator. The lifting function ensures that the rotor 6 is in the same position in the cavity 21 each time, so that each rotor 6 has the repeatability of posture in the cavity 21, which significantly reduces the electromagnetic performance fluctuation caused by assembly. The rotor defect detection process can form a closed-loop control chain with the industrial robot: Loading stage: The robot arm carries the rotor 6 and moves it vertically downwards directly above the cavity 21; Receiving stage: The bearing component 30 rises to the pre-receiving position in advance, and the shaft structure 3010 achieves collision-free docking with the center hole of the rotor; Pressing stage: After the pressing component rotates to the position, it descends, and the shaft structure 3010 also achieves collision-free docking with the center hole of the rotor. The limiting part 3011 stops after contacting the flat end face of the rotor 6. The whole process takes less time, greatly improves efficiency compared to manual operation, and eliminates positioning deviations caused by human factors.

[0076] Referring to Figures 1-7, the bearing assembly 30 includes a support frame 300, which is fixed to the lower side of the test bench 1. A bearing seat 301 is provided on the upper side of the support frame 300. The end face of the bearing seat 301 is provided with a shaft-shaped structure 3010 and a limiting part 3011. The diameter of the bearing seat 301 is adapted to the diameter of the rotor 6. A first lifting cylinder 302 is provided on the lower side of the support frame 300. The piston rod of the first lifting cylinder 302 passes through the support frame 300 and connects to the bearing seat 301.

[0077] The clamping assembly includes a rotary motor 310 disposed below the test bench 1. The output shaft of the rotary motor 310 passes through the surface of the test bench 1 and is connected to a rotating arm 311. The rotating arm 311 is provided with a second lifting cylinder 312. The second lifting cylinder 312 is connected to a clamping seat 313. The end face of the clamping seat 313 is provided with a shaft-shaped structure 3010 and a limiting part 3011.

[0078] During the clamping stage, the support seat 301 is raised to the clamping position by the first lifting cylinder 302, and the rotor 6 is placed on the support seat 301. Its bottom plane is in contact with the limiting part 3011 of the support seat 301, and the bottom shaft structure 3010 is inserted into the center hole of the rotor. The rotating motor 310 drives the rotating arm 311 to rotate directly above the rotor 6, and the second lifting cylinder 312 lowers the pressing seat 313, so that the shaft structure 3010 of the pressing seat 313 is inserted into the center hole of the other end of the rotor 6, and the limiting part 3011 is in contact with the end face of the rotor, thus completing the bidirectional positioning and clamping.

[0079] The stall test primarily identifies symmetrical defects in the rotor bars (such as broken bars or thin bars), as these defects directly lead to current imbalance or abnormal torque. However, internal defects in the end ring 60, such as pores, thermal cracks, microcracks, and component segregation, have a relatively small impact on the overall resistance of the rotor 6 and may be unevenly distributed, making them difficult to reflect through three-phase current balance. Therefore, after completing the first-stage stall test, this device can then conduct the second-stage end ring 60 defect test. In this embodiment, referring to Figures 1-7, the rotating arm 311 includes a vertical beam connected to the motor and a first and second horizontal beam with a designed angle at the ends of the vertical beam. The second lifting cylinder 312 is located on the first horizontal beam, and the third lifting cylinder 314 is located on the second horizontal beam. The piston rod end of the third lifting cylinder 314 is rotatably connected to a conductive element 315. One side of the conductive element 315 can contact the end ring 60 of the rotor 6, and the other side is provided with a stationary brush 316. The bearing seat 301 is rotatably connected to the piston rod end of the first lifting cylinder 302. When the rotor 6 rotates, it drives the bearing seat 301 and the conductive element 315 to rotate synchronously. The brush 316 contacts different parts of the conductive element 315. The brush 316 is connected to a current detection device to collect current parameters to determine the end ring 60 defect.

[0080] Its technical principle is based on the fact that the cast aluminum end ring 60, rotor core, and conductor bars form an internal closed conductive circuit. Under the action of a rotating magnetic field, the rotor conductor bars cut the magnetic field lines to generate an induced electromotive force, driving the current to circulate in the end ring-conductor bar-end ring path. Ideally, the current is uniformly distributed across the cross-section of the end ring 60, and the total current is stable.

[0081] In the forming process of the end ring 60 of the cast aluminum rotor, internal pores are generated due to reasons such as excessive gas content in the melt, poor mold venting, or excessively fast cooling rate. Alternatively, uneven cooling after casting (such as a large temperature gradient in the mold) can cause thermal cracks due to the difference in shrinkage rate between the inner and outer layers of the end ring 60. Rough handling during demolding (such as hitting the mold) can also cause micro-cracks inside the end ring 60. Insufficient centrifugal speed during centrifugal casting can lead to uneven composition of the end ring 60 due to differences in the density of the molten aluminum.

[0082] Cracks inside end ring 60 can block local current paths, and bubbles can reduce the effective conductive area of ​​end ring 60. The presence of defects disrupts the uniform distribution of current, leading to an increase in the difference in current density in different areas of end ring 60, and changes in the total current at the local defect location.

[0083] In this application, the stall test requires ensuring the rotor 6 remains stationary; therefore, a second cylinder and its corresponding clamping seat 313 mechanism are provided. For the end ring 60 detection stage, various parts of the end ring 60 need to be tested. Therefore, a third lifting cylinder 314 is designed to drive a conductive element 315, which rotates relative to the piston rod of the third lifting cylinder 314, to abut against the rotor end ring 60, forming temporary electrical contact. The conductive element 315 needs to possess high conductivity (such as copper or copper alloy) and wear resistance to reduce contact resistance and wear. A stationary brush 316 is fixed to the other side of the conductive element 315 and connected to a current detection device (such as a high-precision milliohm meter or oscilloscope). The material of the brush 316 needs to balance conductivity and elasticity (such as silver-graphite composite material) to ensure continuous and stable contact.

[0084] When the rotor 6 rotates under the drive of the rotating magnetic field, it drives the bearing seat 301, which can rotate relative to the piston rod of the first lifting cylinder 302, and the conductive element 315 to rotate synchronously. The brush 316 slides relative to the conductive element 315 because it is stationary, forming a "rotational contact-static acquisition" mode, realizing continuous scanning of the current of the end ring 60 throughout the entire circumference.

[0085] When there are no defects, the contact point of the 316 brush moves uniformly along the circumference of the end ring 60, and the current detection device records a stable current waveform (constant amplitude and frequency).

[0086] Defect conditions: When the 316 brush sweeps across the defect area, a sudden change in contact resistance causes instantaneous current fluctuations (such as spikes, dips, or increased noise). Cracks may cause high-frequency current oscillations, while bubbles cause low-frequency current attenuation.

[0087] Angle-current correlation: By combining the rotor 6 rotation angle encoder, a correspondence between current fluctuations and the physical position of the end ring 60 is established. For example, if the current shows a continuous attenuation at the 270° position, it can be inferred that there are bubbles or other defects in that area.

[0088] The proposed solution does not require disassembling the rotor 6. Online detection is achieved through contact-type electrical signal acquisition. The brush 316 continuously scans the entire circumference of the end ring 60, avoiding missed detection of local defects. The rotation of the rotor 6 is generated by the magnetic field generating unit, eliminating the need for additional drive components.

[0089] Furthermore, the rotor end ring 60 structure is designed for different application scenarios, including planar, single-blade, single-balance column, and composite end ring 60 that integrates both blades and balance column. To ensure efficient electrical contact between the conductive component 315 and the end ring 60, the geometry of the contact surface of the conductive component 315 is customized according to the surface contour characteristics of the end ring 60, so that it can be precisely adapted to the surface of the end ring 60. The contact surface between the conductive component 315 and the brush 316 is planar, which facilitates the consistency of contact data acquisition by the brush 316.

[0090] Specifically, the contact surface of the conductive element 315 is provided with a clearance structure (such as a groove) to accommodate protruding features such as balance pillars and fan blades on the surface of the end ring 60. This structural adaptation design can eliminate gaps between contact surfaces, enabling the conductive element 315 to form a tight physical contact with the end ring 60, thereby reducing contact resistance and improving current transmission efficiency.

[0091] Furthermore, the conductive component 315 is a copper plate ring, and an insulating bearing is provided on the outer side of the piston rod end of the third lifting cylinder 314, with the copper plate ring rotatably connected to the insulating bearing.

[0092] The copper plate ring 315, acting as a conductive component, is designed with a diameter that matches the size of the rotor end ring 60, ensuring that the brush 316 can fully contact the copper plate ring, i.e., fully contact the end ring 60. To prevent the traditional metal bearing from creating an electrical path between the copper plate ring and the mechanical structure (such as a cylinder or frame), causing current shunting and resulting in measurement errors, an insulated bearing is used instead of a metal bearing to cut off the electrical connection path. An integral ceramic bearing can be used. Its core function is to block the current conduction path through the bearing. In a specific implementation, the piston rod end can be machined into a bearing mounting shaft, fitted into the inner ring of the insulated bearing, and the copper plate ring is fixed to the outer ring of the insulated bearing.

[0093] In a preferred embodiment of this application, the brush 316 is fixed to the piston rod of the third lifting cylinder 314 by a bracket and is located on the upper side of the conductive element 315. The bracket can be an L-shaped bracket, with the horizontal arm fixing the brush 316 and the vertical arm connecting the cylinder piston rod. The brush 316 can be detached from the bracket for easy replacement.

[0094] As a preferred embodiment of this application, it also includes a control system 41, which is electrically connected to the magnetic field generating unit, the rotor clamp unit and the constant temperature control unit to intelligently control the operation of each unit.

[0095] The detection method of the cage-type cast aluminum rotor defect detection device includes the following steps:

[0096] S1: Deshelling treatment of cast aluminum rotor

[0097] Rotor transfer: Rotor 6 on the cast aluminum rotor production line is transferred from the conveyor belt to the rotor outer circle cleaning machine by the first robot arm;

[0098] Outer diameter chip removal: Utilizing the residual heat from the cast aluminum rotor, a flexible scraper or wire wheel is used to remove aluminum chips and impurities from the outer diameter of the rotor.

[0099] Friction heating: During the chip removal process, heat is generated by the friction between the scraper / wire wheel and the outer circle of the rotor 6, which raises the surface temperature of the rotor to the aluminum strip descaling process temperature, which is more energy-efficient than heating in a furnace.

[0100] Rapid cooling and descaling: The second robotic arm quickly immerses the rotor 6 in the coolant for rapid cooling. By utilizing the difference in thermal expansion coefficients between aluminum and silicon steel sheets, a gap is created between the aluminum strip and the silicon steel sheet, thus completing the descaling process.

[0101] The descaling process breaks the mechanical bond between the aluminum strip and the silicon steel sheet through a hot-cold rapid change, ensuring that defects in the aluminum strip can be accurately detected in subsequent tests.

[0102] S2: Rotor positioning

[0103] The bearing seat 301 is lifted: The piston rod of the first lifting cylinder 302 on the test bench 1 is lifted, the bearing seat 301 enters the cavity 21 and protrudes from the upper surface, and the end face shaft structure 3010 and the limiting part 3011 are exposed.

[0104] Rotor loading: The third robotic arm aligns the center hole of the deshelled rotor with the shaft-shaped structure of the bearing seat 301 to complete the mating connection;

[0105] Rotor descent: The piston rod of the first lifting cylinder 302 descends, transferring the rotor 6 to the designed position of the cavity 21 (at the same height as the magnetic field generating unit to ensure magnetic field coverage).

[0106] The axial structure and limiting part of the bearing seat end face ensure the axial positioning accuracy of the rotor 6, and avoid current acquisition errors caused by eccentricity during testing;

[0107] S3: Rotor clamping and fixing

[0108] Positioning of the clamping seat: The rotating motor drives the second lifting cylinder 312 to be directly above the cavity 21, and the shaft structure 3010 on the end face of the clamping seat 313 is aligned with the center hole of the rotor 6;

[0109] Insertion and clamping: The second lifting cylinder 312 descends, and the axial structure and limit of the end face of the clamping seat 313 do not achieve insertion and engagement with the center hole of the rotor 6, applying axial pressure to ensure that the rotor 6 does not rotate;

[0110] The clamping force needs to be balanced to test stability and the risk of rotor deformation.

[0111] S4: Guide bar defect detection

[0112] Magnetic field loading: Activate the magnetic field generating unit to produce a rotating magnetic field;

[0113] Locked rotor current acquisition: The defect monitoring device acquires the three-phase locked rotor current of the stator winding 20 to analyze the three-phase balance and harmonic content;

[0114] Temperature control: The temperature sensor monitors the temperature of the magnetic field generating unit in real time. When the temperature exceeds the limit, the cooling components (air cooling / water cooling) are triggered to maintain the target temperature range.

[0115] Guide bar defect types:

[0116] Broken bar: Three-phase locked rotor current deviation >5% (e.g., the current of phase A is more than 10% lower than that of phases B and C), due to magnetic circuit asymmetry caused by broken bar;

[0117] Thin strip: Current deviation of 3%-5% is due to increased resistance caused by insufficient cross-sectional area of ​​aluminum strip.

[0118] Porosity / looseness: Increased current harmonic content, caused by magnetic field distortion due to internal defects in the aluminum strip;

[0119] S5: End-ring defect detection

[0120] Qualified rotor transfer: If the guide bar is qualified, the third lifting cylinder 314 rotates to the top of the cavity 21, and the piston rod descends to make the conductive part 315 in close contact with the rotor end ring 60.

[0121] Rotation test: Restart the magnetic field generating unit, and the rotor 6 rotates in the rotating magnetic field. The current value is collected at multiple points around the contact end ring 60 of the brush 316.

[0122] Defect judgment: If the deviation of multiple current values ​​is >3% (e.g., the difference between the maximum and minimum values ​​exceeds 3% of the average value), the end ring 60 is judged to be unqualified;

[0123] End ring 60 defect type:

[0124] Cracks: Cracks are usually located in specific locations, and the current value fluctuates periodically (the frequency is synchronized with the rotor speed). The contact resistance changes due to the cracks.

[0125] Pores: The distribution of pores within the end ring 60 is mostly random. The presence of pores will disrupt the continuity of the metal in the end ring 60, leading to increased contact resistance and increased resistance non-uniformity. Current will be hindered when passing through the pore area, resulting in irregular fluctuations in current value. The resistance changes caused by pores are usually irregular.

[0126] S6: Sorting and Circulation

[0127] Non-conforming handling: When the guide bar or end ring 60 fails the test, the magnetic field generating unit is shut down, the second lifting cylinder 312 is raised and rotated away from the cavity 21, the first lifting cylinder 302 lifts the rotor 6, and the robot is transferred to the defective work station;

[0128] Qualified transfer: When the inspection is qualified, the rotor 6 is lifted by the first lifting cylinder 302 and transferred by the robot to the qualified station to enter the next process.

[0129] The sorting logic is controlled by a PLC, achieving full automation of detection and sorting. See the table below.

[0130]

[0131] This application's solution achieves full quality control of cast aluminum rotors through a process of "shell removal - positioning - clamping - guide bar detection - end ring detection - sorting," with high detection accuracy, making it suitable for efficient automated production lines.

[0132] For any parts not mentioned in this invention, existing technologies can be used or referenced.

[0133] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in the present invention, and these should all be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A cage-type cast aluminum rotor defect detection device, characterized in that, It includes a test bench, which is equipped with a magnetic field generating unit, a rotor clamping unit, a defect monitoring device, and a constant temperature control system. The magnetic field generating unit includes a stator winding and a constant voltage power supply, which is used to generate a rotating detection magnetic field. The center of the stator winding has a cavity for placing the rotor. The rotor clamping unit is located above and below the detection area of ​​the magnetic field generating unit. It includes an axial clamping mechanism to fix the rotor to be inspected and ensure that the rotor axis coincides with the stator winding axis. The defect monitoring device is electrically connected to the magnetic field generating unit to collect electrical parameters and identify the defect characteristics of the rotor bar. The constant temperature control unit includes a temperature sensor and a cooling component. The temperature sensor monitors the operating temperature of the magnetic field generating unit in real time. When the temperature exceeds a preset threshold, the cooling component is triggered to maintain the magnetic field generating unit within the target detection temperature range to ensure test consistency. The axial clamping mechanism includes a bearing component and a clamping component. The bearing component is located directly below the cavity and has a lifting function. The clamping component is located on one side of the magnetic field generating unit, can rotate to the upper side of the cavity, and has a lifting function. Both the bearing assembly and the clamping assembly are equipped with a shaft-shaped structure adapted to the rotor's central hole, and a limiting part is provided below the shaft-shaped structure. The shaft-shaped structure can pass into the rotor shaft hole, and the limiting part abuts against the rotor's planar end face. The bearing assembly includes a support frame, which is fixed to the lower side of the test bench. A bearing seat is provided on the upper side of the support frame. The end face of the bearing seat is equipped with a shaft-shaped structure and a limiting part. The diameter of the bearing seat is adapted to the diameter of the rotor. A first lifting cylinder is provided on the lower side of the support frame, and the piston rod of the first lifting cylinder passes through the support frame and connects to the bearing seat. The clamping assembly includes a rotating motor located below the test bench. The output shaft of the rotating motor passes through the test bench surface and connects to a rotating arm. A second lifting cylinder is provided on the rotating arm. Two lifting cylinders are connected to a clamping seat. The end face of the clamping seat is provided with the shaft-like structure and the limiting part. The rotating arm includes a vertical beam connected to a rotating motor and a first and second horizontal beam with a designed angle at the ends of the vertical beam. The second lifting cylinder is located on the first horizontal beam, and a third lifting cylinder is located on the second horizontal beam. The piston rod end of the third lifting cylinder is rotatably connected to a conductive component. One side of the conductive component can contact the end ring of the rotor, and the other side is provided with a stationary brush. The bearing seat is rotatably connected to the end of the piston rod of the first lifting cylinder. When the rotor rotates, it drives the bearing seat and the conductive component to rotate synchronously. The brush contacts different parts of the conductive component. The brush is connected to a current detection device to collect current parameters to determine the end ring defect.

2. The cage-type cast aluminum rotor defect detection device according to claim 1, characterized in that, The cooling assembly includes a cooling shroud disposed on the outer periphery of the stator winding. The cooling shroud has an inlet and an outlet, as well as a spiral flow channel connecting the inlet and the outlet. The inlet is connected to the outlet of the heat exchanger through a first pipe, and the outlet is connected to the inlet of the heat exchanger through a second pipe.

3. The cage-type cast aluminum rotor defect detection device according to claim 1, characterized in that, The shape of the contact surface of the conductive component is adapted to the surface contour of the rotor end ring; the contact surface is provided with a clearance structure to accommodate the balance column or fan blade on the surface of the end ring, so that the conductive component is in close contact with the end ring.

4. The cage-type cast aluminum rotor defect detection device according to claim 1, characterized in that, The conductive component is a copper plate ring, and an insulating bearing is provided on the outer side of the piston rod end of the third lifting cylinder. The copper plate ring is rotatably connected to the insulating bearing.

5. The cage-type cast aluminum rotor defect detection device according to claim 1, characterized in that, The brush is fixed to the piston rod of the third lifting cylinder by a bracket and is located on the upper side of the conductive component.

6. The cage-type cast aluminum rotor defect detection device according to claim 1, characterized in that, It also includes a control system, which is electrically connected to the magnetic field generating unit, the rotor clamping unit, and the constant temperature control unit to intelligently control the operation of each unit.

7. A detection method based on the cage-type cast aluminum rotor defect detection device according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1: Descaling of Cast Aluminum Rotors On the cast aluminum rotor production line, the rotors are transferred from the conveyor belt to the rotor outer diameter cleaning machine by the first robotic arm. Utilizing the residual heat from the cast aluminum rotor, the outer diameter of the rotor is cleaned by a flexible scraper or wire wheel to remove aluminum chips and impurities. During the cleaning process, heat is generated due to the friction between the scraper / wire wheel and the outer diameter of the rotor, causing the rotor surface temperature to rise to the aluminum strip descaling process temperature. The second robotic arm quickly immerses the rotor in a cooling liquid for rapid cooling. Utilizing the difference in thermal expansion coefficients between aluminum and silicon steel sheets, a gap is created between the aluminum strips and the silicon steel sheets, completing the descaling process. S2: The rotor positioning support is lifted, the piston rod of the first lifting cylinder on the test platform is lifted, the support enters the cavity and protrudes from the upper surface, the end face shaft structure and limiting part are exposed, the third robot arm aligns the deshelled rotor center hole with the shaft structure of the support to complete the mating connection, the piston rod of the first lifting cylinder descends, and the rotor is transferred to the designed position in the cavity; S3: The rotor clamping and fixing rotation motor drives the second lifting cylinder to directly above the cavity, the end face shaft structure of the clamping seat is aligned with the rotor center hole, the second lifting cylinder descends, the clamping seat and the rotor center hole are plugged in, axial pressure is applied to ensure that the rotor does not rotate; S4: The guide bar defect detection starts the magnetic field generation single The magnetic field generating unit generates a rotating magnetic field. The defect monitoring device collects the three-phase stall current of the stator winding and analyzes the three-phase balance and harmonic content. The temperature sensor monitors the temperature of the magnetic field generating unit in real time. When the temperature exceeds the limit, the cooling component is triggered to maintain the temperature range of the stator winding and prevent the resistance from changing, which would cause measurement errors. S5: End ring defect detection. If the conductor bar is qualified, the third lifting cylinder of the magnetic field generating unit is turned off and rotated to the top of the cavity. The piston rod descends to make the conductive parts make close contact with the rotor end ring. The magnetic field generating unit is restarted. The rotor rotates in the rotating magnetic field. The brush contacts the end ring for one revolution and collects multiple current values. If the deviation of the multiple current values ​​is greater than the design parameters, the end ring is judged to be unqualified. S6: Handling of non-conforming sorting and transfer: When the guide bar or end ring fails the inspection, the magnetic field generating unit is shut down, the second lifting cylinder rises and rotates away from the cavity, the first lifting cylinder lifts the rotor, and the robot transfers it to the defective station; Conforming transfer: When both the guide bar and end ring pass the inspection, the rotor is lifted by the first lifting cylinder and transferred to the conforming station by the robot.

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