A vertical rotating tester test rotor crack on-line monitoring device and method

Abstract

The application discloses a vertical rotary tester test rotor crack online monitoring device and method. The device comprises a vibration sensor, a key phase sensor, an online monitoring system signal processing module and a crack monitoring and analyzing module. The vibration sensor installed on the main shaft system is used to obtain the vibration original signal of the main shaft system, the key phase sensor installed on the main shaft system is used to obtain the pulse signal generated by the rotor rotation in one round, the signal transmitted by the vibration sensor and the key phase sensor is processed through the online monitoring system signal processing module, the rotor vibration amplitude and the rotor rotating speed are obtained, and are transmitted to the crack monitoring and analyzing software, then the maximum amplitude of the rotor and the rotating speed value when the maximum amplitude is generated are monitored and analyzed to determine the initiation and expansion of the rotor crack. The abnormal alarm prompt of the crack online monitoring system is helpful to prevent the rotor rupture caused by the initiation and expansion of the test rotor crack, so that the advance shutdown inspection is realized.

Description

Technical Field

[0001] This invention relates to an online monitoring device and method for rotor cracks in a vertical rotating tester, and more particularly to an online monitoring and testing device and method for determining the initiation and propagation of rotor cracks during low-cycle fatigue testing based on the variation law of the rotor's maximum amplitude and the rotational speed at which the maximum amplitude is generated with the number of cycles. This invention belongs to the field of low-cycle fatigue testing of aero-engine rotors. Background Technology

[0002] Modern aero-engines place increasingly higher demands on high thrust-to-weight ratios and long service life, forcing engine rotor components to develop towards high strength, long service life, and low weight. Aero-engine high-speed rotating components operate under extreme loads and harsh environments of high temperature, high pressure, and high centrifugal force for extended periods. Prolonged operation and frequent start-stop cycles can easily cause the stress on the rotor to reach the low-cycle fatigue limit of the material, leading to the initiation of low-cycle fatigue cracks. If these cracks propagate further, they can cause rotor failure. The rotor is a critical component of an aero-engine, and its failure seriously jeopardizes flight safety. Therefore, major aviation powers attach great importance to the low-cycle fatigue problem of aero-engine rotor components, and rigorously examine their low-cycle fatigue performance in design and operation management. During the testing of the low-cycle fatigue performance of rotor components, particular attention must be paid to monitoring the crack initiation and propagation processes.

[0003] Currently, the main experimental methods and principles for rotor crack monitoring are as follows: vibration sensors are installed to acquire the raw vibration signal of the spindle system, and key phase sensors are installed to acquire the zero-position reference signal of the rotor rotation and the rotor speed. When a crack or other abnormality occurs in the rotor, it causes changes in the magnitude and phase of the rotor system's imbalance, resulting in corresponding changes in the peak amplitude and phase of the rotor system's vibration. Therefore, by monitoring the changes in the peak amplitude and phase of the rotor system's vibration, it is possible to determine whether the rotor system has cracks or other abnormalities. However, this method, which relies on the changes in the magnitude and phase of the rotor system's imbalance leading to changes in the peak amplitude and phase of the rotor system at its maximum speed, is more suitable for rigid rotor systems. For flexible rotors, after exceeding the critical speed, the changes in imbalance caused by the rotor's self-alignment have a smaller impact on the maximum vibration amplitude, and in many cases, it is impossible to form an accurate judgment characteristic pattern.

[0004] Therefore, there is an urgent need for a testing device and method that can intuitively and accurately monitor cracks in experimental rotors online. This device should be able to obtain a curve showing the maximum rotor amplitude and the rotational speed at which the maximum amplitude occurs, based on the rotor vibration and pulse signals generated per revolution measured by sensors, as well as the curves showing the change in the number of revolutions. Based on these changing patterns, the device can infer the initiation and propagation of cracks, thereby determining whether cracks have initiated and propagated during rotor rotation cycles. When the online crack monitoring and analysis module detects an abnormal signal—that is, the vibration peak value gradually increases with the number of revolutions, and the location of the maximum vibration amplitude changes from the critical speed to the highest speed and the amplitude exceeds the limit—the online crack monitoring and analysis module issues a rotor abnormality alarm, stopping the machine for a thorough inspection of the location and length of crack initiation and propagation in the experimental rotor. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by creatively implementing an online crack monitoring system to achieve online monitoring of cracks in the test rotor of a vertical rotating tester. It provides an online monitoring and testing device and method for determining the initiation and propagation of cracks in the rotor during low-cycle fatigue testing based on the law of change of the rotor's maximum amplitude and the rotational speed at which the maximum amplitude is generated with the number of cycles.

[0006] The basic principle of this technique is to use vibration sensors installed on the spindle system to acquire the raw vibration signals during the spindle's acceleration and deceleration process, and to use key phase sensors installed on the spindle system to acquire the pulse signals of one rotor rotation. The online monitoring system's signal processing module acquires the rotor vibration amplitude and rotor speed. After signal identification and processing, the presence and propagation of cracks are determined by monitoring and analyzing the maximum rotor amplitude and the rotational speed at which the maximum amplitude occurs, as a function of the number of cycles. When conducting low-cycle fatigue tests on the test rotor, a flexible rotor is typically used. Generally, the maximum vibration peak generated during rotor acceleration and deceleration occurs at the critical speed. After the acceleration exceeds the critical speed, the rotor automatically centers, and the vibration decreases. If the rotor imbalance does not change, the maximum vibration amplitude is stable. Therefore, two regular straight lines can be obtained for each cycle's vibration peak and corresponding rotational speed. When a crack develops in the rotor, the vibration peak gradually increases with the number of cycles and crack propagation. Since the opening of the rotor crack at the peak speed leads to an increase in the overall rotor imbalance, the location of the maximum vibration amplitude shifts from the critical speed to the highest speed. During the transition, the location of the maximum vibration amplitude can be observed to fluctuate between the critical speed and the maximum speed, eventually stabilizing at the maximum speed. As the crack continues to propagate, the peak vibration and corresponding speed curves change with the increase of the number of cycles. When the vibration amplitude exceeds the set limit at the maximum speed, the machine is stopped for inspection.

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

[0008] On one hand, the present invention provides an online monitoring device for cracks in a test rotor of a vertical rotary testing machine, comprising a vibration sensor, a key phase sensor, an online monitoring system signal processing module, and an online crack monitoring and analysis module. The vibration sensor is installed on the spindle system of the vertical rotary testing machine to acquire the original vibration signal of the spindle system. The key phase sensor is installed on the spindle system of the vertical rotary testing machine to acquire one or more pulse signals generated by one revolution of the test rotor. The online monitoring system signal processing module processes the signals from the vibration sensor and the key phase sensor to acquire the rotor vibration amplitude and rotor speed, and transmits them to the online crack monitoring and analysis module. The online crack monitoring and analysis module monitors and analyzes the change of the maximum rotor amplitude and the rotational speed value at which the maximum amplitude is generated with the increase of the rotor speed cycle number, thereby determining whether cracks initiate and propagate during the rotor speed cycle.

[0009] On the other hand, the present invention provides a test method based on the online monitoring device for rotor cracks in the vertical rotating tester, which includes the following steps:

[0010] 1) The vibration sensor is mounted on one side of the rotating spindle via a sensor bracket, and the key phase sensor is mounted on the same side via the same sensor bracket. The vibration sensor determines the distance between the sensor probe and the object being measured by measuring the strength of the eddy current signal. By adjusting the radial clearance between the vibration sensor and the outer cylindrical surface of the rotating spindle, the vibration sensor can acquire a stable eddy current induced signal. The key phase sensor determines whether the sensor probe passes through or not through the notch set on the rotating spindle by measuring the presence and disappearance of the electromagnetic induction signal. By adjusting the clearance between the key phase sensor and the outer cylindrical surface of the rotating spindle, the key phase sensor can acquire a stable electromagnetic induction signal. The spindle is rotated slowly. When the notch on the spindle passes through the key phase sensor, the electromagnetic induction signal of the key phase sensor disappears.

[0011] 2) Connect the vibration sensor and key phase sensor to the signal processing module of the online monitoring system, and connect the signal processing module of the online monitoring system to the online crack monitoring and analysis module; while the tester is rotating, connect and debug the sensor and signal transmission line until the sensor and signal transmission line can operate normally, and the online crack monitoring and analysis module can complete data recording and analysis and display the curve of vibration amplitude changing with rotation speed normally.

[0012] 3) Install the test rotor to the lower end of the drive shaft of the vertical rotary tester, turn on the main power of the vertical rotary tester, set the rotor outer diameter, axial height, weight, and moment of inertia, set the target test speed and holding time, and then drive the test rotor from zero speed to accelerate to the target test speed and stabilize for 30 seconds before decelerating back to zero speed. This is to check whether the vibration sensor and key phase sensor are affected and fall off during the test rotor speed-up process, check and determine the critical speed and the maximum vibration amplitude when passing the critical speed, and record them.

[0013] 4) Conduct online crack monitoring during the low-cycle fatigue test of the test rotor of the vertical rotary tester. Specifically, turn on the online crack monitoring and analysis module of the test rotor of the vertical rotary tester, input the rotor outer diameter, axial height, weight, and moment of inertia, set the upper limit speed, lower limit speed, holding time, and target total number of cycles, then drive the test rotor to increase the speed to the upper limit speed and hold time, then decrease the speed to the lower limit speed and hold time, and then continue to increase the speed to start the cycle with the same speed waveform until the target total number of cycles is reached and then stop the machine.

[0014] When the online crack monitoring and analysis module detects that the location of the vibration peak fluctuates between the critical speed and the maximum speed, and eventually changes to the maximum speed, the online crack monitoring and analysis module determines that crack initiation has occurred in the rotor.

[0015] After the crack initiation, the online crack monitoring and analysis module found that as the number of cycles increased, the vibration peak value of the rotor at the highest speed during each cycle of acceleration continuously increased. Therefore, the online crack monitoring and analysis module determined that the initiated crack had expanded.

[0016] When the peak value of rotor vibration exceeds the first-level amplitude limit set by the tester, the online crack monitoring and analysis module issues a rotor abnormality alarm; when the peak value of rotor vibration exceeds the second-level amplitude limit set by the tester, the online crack monitoring and analysis module triggers the test machine to stop for inspection.

[0017] Furthermore, after the test is completed, the machine is stopped to inspect the location and length of crack initiation in the test rotor.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The testing device and method provided by this invention use the variation of rotor vibration amplitude and the rotational speed corresponding to the maximum vibration amplitude with the low number of rotor cycles as the judgment basis. This can provide fault characteristic reference signals more simply and accurately, which helps to prevent rotor breakage caused by crack initiation and crack propagation in the test rotor. This allows for early shutdown for inspection, effectively determining the occurrence of rotor crack faults, and greatly reducing the number of shutdowns for inspections caused by misjudged faults. This speeds up the test cycle and reduces test costs.

[0020] 2. This invention uses the most common sensors and develops a special online monitoring module for cracks in the test rotor of a vertical rotating tester, which ensures that the device structure is simple while improving the online monitoring capability for crack initiation and crack propagation in the test rotor. Attached Figure Description

[0021] Figure 1 Structural diagram of an online monitoring and testing device for rotor cracks in a vertical rotary tester;

[0022] Figure 2 for Figure 1 Block diagram of the signal processing module of the online monitoring system;

[0023] Figure 3 The graph shows the variation of the maximum vibration amplitude of the test rotor and the corresponding test rotor speed with the number of cycles.

[0024] In the diagram: 1. Rotating spindle, 2. Vibration sensor, 3. Signal processing module of online monitoring system, 4. Online crack monitoring and analysis module, 5. Test rotor, 6. Key phase sensor. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] like Figure 1 and Figure 2 As shown, the online monitoring and testing device for cracks in the test rotor of the vertical rotating tester of the present invention includes an eddy current vibration displacement sensor 2, an eddy current key phase sensor 6, an online monitoring system signal processing module 3, and an online crack monitoring and analysis module 4.

[0027] The eddy current vibration displacement sensor 2 is used to acquire the raw signal of the vibration displacement of the spindle system. It is mounted on one side of the rotating spindle 1 via a sensor bracket. The eddy current key phase sensor 6 is used to acquire the raw pulse signal generated by one revolution of the rotor. It is also mounted on one side of the rotating spindle 1 via a sensor bracket. The vibration sensor 2 determines the distance between the sensor probe and the object being measured by measuring the strength of the eddy current signal. By adjusting the radial clearance between the vibration sensor 2 and the outer cylindrical surface of the rotating spindle 1, the vibration sensor can acquire a stable eddy current induced signal. The key phase sensor determines whether the sensor probe passes through or not through a notch on the rotating spindle by measuring the presence and disappearance of the electromagnetic induction signal. By adjusting the clearance between the key phase sensor 6 and the outer cylindrical surface of the rotating spindle 1, the key phase sensor can acquire a stable electromagnetic induction signal. When the spindle is rotated slowly, the electromagnetic induction signal of the key phase sensor disappears when the notch on the spindle passes through the key phase sensor.

[0028] like Figure 2The diagram shows the composition and principle of the signal processing module of the online monitoring system. The signal processing module 3 processes the raw signals from the eddy current vibration displacement sensor and the eddy current key phase sensor to obtain the rotor vibration amplitude and rotor speed, and then sends them to the online crack monitoring and analysis module. In a specific embodiment of the invention, the raw vibration signal from the vibration displacement sensor is similar to a sine wave, and the rotor vibration amplitude is calculated by taking the peak-to-peak value; the pulse signal from the eddy current key phase sensor is similar to a square wave, and the number of square waves is counted within a certain time period to convert it into the number of pulses per minute, i.e., the rotor speed r / min.

[0029] The online crack monitoring and analysis module 4 is used to monitor and analyze the maximum vibration amplitude during the acceleration and deceleration process of the test rotor in the low-cycle fatigue test, as well as the variation of the rotational speed value with the number of cycles when the maximum vibration amplitude is generated, so as to determine whether cracks have started and expanded.

[0030] Specifically, the principle upon which the online crack monitoring and analysis module 4 of the present invention judges crack initiation is as follows: When the test rotor is subjected to a low-cycle fatigue test, a flexible rotor is used. The maximum vibration peak generated during the rotor speed increase and decrease occurs at the critical speed position. After the speed increase exceeds the critical speed, the rotor automatically centers and the vibration decreases. If the rotor imbalance does not change, the maximum vibration amplitude value is stable. Therefore, two regular straight lines can be obtained for each cycle vibration peak and the corresponding speed.

[0031] When a crack develops in the rotor, the crack will open under centrifugal load, causing the overall rotor imbalance to increase with the increase of rotational speed. The imbalance is greatest at the highest rotational speed, and the location of the maximum vibration amplitude changes from the critical speed to the highest rotational speed. During the transition, the location of the maximum vibration amplitude can be observed to jump back and forth between the critical speed and the highest rotational speed, eventually stabilizing at the highest rotational speed.

[0032] Therefore, when the online crack monitoring and analysis module detects that the location of the vibration peak fluctuates between the critical speed and the maximum speed, and eventually shifts to the maximum speed, the module determines that a crack has initiated in the rotor. After crack initiation, the module further detects that with the increase in the number of cycles, the vibration peak of the rotor at the maximum speed continuously increases during each cycle's acceleration, indicating that the initiated crack has propagated.

[0033] For the safety of the test, the online crack monitoring and analysis module 4 is also equipped with a test safety module. When the peak value of the rotor vibration exceeds the first-level amplitude limit set by the tester, the online crack monitoring and analysis module issues a rotor abnormality alarm; when the peak value of the rotor vibration exceeds the second-level amplitude limit set by the tester, the online crack monitoring and analysis module triggers the test machine to stop for inspection.

[0034] The principle of the online crack monitoring and analysis module for an online monitoring method of cracks in a vertical rotating test rotor, implemented through the aforementioned testing device, is as follows:

[0035] The original vibration signal during the spindle acceleration and deceleration process is acquired using an eddy current vibration displacement sensor installed on the spindle system. The pulse signal of one rotor rotation is acquired using an eddy current key phase sensor installed on the spindle system, thus obtaining the rotor vibration amplitude and rotor speed. After signal identification and processing, the presence and propagation of cracks are determined by monitoring and analyzing the variation of the maximum rotor amplitude and the rotational speed at which the maximum amplitude occurs with the number of cycles. When conducting low-cycle fatigue tests on the test rotor, a flexible rotor is typically used. Generally, the maximum vibration peak value during rotor acceleration and deceleration occurs at the critical speed. After the acceleration exceeds the critical speed, the rotor automatically centers and the vibration decreases. If the rotor imbalance does not change, the maximum vibration amplitude value is stable. Therefore, two regular straight lines can be obtained for the vibration peak value and the corresponding rotational speed for each cycle. When a crack initiates in the rotor, the vibration peak value gradually increases with the number of cycles and crack propagation. Since the opening of the rotor crack at the peak speed leads to an increase in the overall rotor imbalance, the location of the maximum vibration amplitude shifts from the critical speed to the highest speed. During the transformation process, the location of the maximum vibration amplitude can be observed to fluctuate between the critical speed and the maximum speed, eventually stabilizing at the maximum speed. A typical curve showing the change in peak vibration and corresponding speed with increasing cycle number as the crack continues to propagate is attached. Figure 3 As shown. When the vibration amplitude exceeds the set limit at the highest speed, stop the machine for inspection.

[0036] The test method for online monitoring of rotor cracks using a vertical rotating tester of the present invention includes the following steps:

[0037] 1) Sensor Installation and Adjustment. The vibration sensor 2 is mounted on one side of the rotating spindle 1 via a sensor bracket, and the key phase sensor 6 is mounted on the same side of the rotating spindle 1 via the same sensor bracket. The vibration sensor 2 determines the distance between the sensor probe and the object being measured by measuring the strength of the eddy current signal. By adjusting the radial clearance between the vibration sensor 2 and the outer cylindrical surface of the rotating spindle 1, the vibration sensor can acquire a stable eddy current induction signal. The key phase sensor determines whether the sensor probe passes through or not through the notch set on the rotating spindle by measuring the presence and disappearance of the electromagnetic induction signal. The clearance between the key phase sensor 6 and the outer cylindrical surface of the rotating spindle 1 is adjusted to ensure the key phase sensor acquires a stable electromagnetic induction signal. The spindle is rotated slowly; when the notch on the spindle passes through the key phase sensor, the electromagnetic induction signal of the key phase sensor disappears.

[0038] 2) Monitoring System Connection and Debugging. Connect the eddy current vibration displacement sensor 2 and the eddy current key phase sensor 6 to the online monitoring system signal processing module 3, and connect the online monitoring system signal processing module 3 to the crack monitoring and analysis software 4. Perform connection and debugging of the system under low-speed rotation to verify that the system can operate normally and that the crack monitoring and analysis software 4 can complete data recording and analysis and correctly display the curve of vibration amplitude changing with rotational speed.

[0039] 3) Rotor single-cycle test. Install the test rotor to the lower end of the drive shaft of the vertical rotary testing machine, turn on the main power of the vertical rotary testing machine, open the rotor overspeed test software, input parameters such as rotor outer diameter, axial height, weight, and moment of inertia, set the target test speed and holding time, click start, drive the test rotor to accelerate from zero speed to the target test speed, stabilize the speed for 30 seconds, and then decelerate back to zero speed. Check whether the vibration sensor 2 and key phase sensor 6 are affected or fall off during the rotor acceleration process, check and determine the critical speed and the maximum vibration amplitude when passing the critical speed, and record them for reference in subsequent low-cycle fatigue tests.

[0040] 4) Conduct online crack monitoring during the low-cycle fatigue test of the vertical rotary testing machine rotor. Open the online crack monitoring and analysis software for the vertical rotary testing machine rotor, locate the low-cycle fatigue test piece for the testing machine rotor, input parameters such as rotor outer diameter, axial height, weight, and moment of inertia, set test parameters such as upper limit speed, lower limit speed, hold time, and target total number of cycles, click start, drive the test rotor to accelerate to the upper limit speed and hold time, then decelerate to the lower limit speed and hold time, then continue accelerating to begin cycling with the same speed waveform until the target total number of cycles is reached, then stop the machine. When the online crack monitoring and analysis module detects that the location of the vibration peak fluctuates between the critical speed and the maximum speed, and eventually shifts to the maximum speed, the online crack monitoring and analysis module determines that a crack has started in the rotor. After crack initiation, the online crack monitoring and analysis module further detects that as the number of cycles increases, the vibration peak of the rotor at the maximum speed during each cycle of acceleration continuously increases, thus determining that the initiated crack has expanded. When the rotor vibration peak exceeds the first-level amplitude limit set by the tester, the online crack monitoring and analysis module issues a rotor abnormality alarm. When the rotor vibration peak exceeds the second-level amplitude limit set by the tester, the online crack monitoring and analysis module triggers the test machine to stop for inspection. Figure 3The diagram shows the variation of the maximum vibration amplitude and corresponding rotor speed with the number of cycles during the specific test process of this invention. Through the above tests, the abnormal alarm prompts from the online crack monitoring system help prevent rotor breakage caused by crack initiation and propagation, thus allowing for earlier shutdown and inspection. Effectively identifying crack initiation and propagation faults significantly reduces the number of shutdowns due to false faults, thereby accelerating the test cycle and reducing test costs.

[0041] The above examples are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of the present invention should be considered within the scope of protection of the present invention.

Claims

1. An online monitoring device for cracks in a vertical rotating test rotor, characterized in that, The system includes a vibration sensor (2), a key phase sensor (6), an online monitoring system signal processing module (3), and an online crack monitoring and analysis module (4). The vibration sensor (2) is installed on the spindle system of the vertical rotating tester to acquire the original vibration signal of the spindle system. The key phase sensor (6) is installed on the spindle system of the vertical rotating tester to acquire one or more pulse signals generated by the test rotor rotating once. The online monitoring system signal processing module (3) is used to process the signals from the vibration sensor and the key phase sensor to acquire the rotor vibration amplitude and rotor speed, and send them to the online crack monitoring and analysis module (4). The online crack monitoring and analysis module (4) is used to monitor and analyze the law of change of the rotor maximum amplitude and the speed value when the maximum amplitude is generated with the increase of the rotor speed cycle number, so as to determine whether there is crack initiation and propagation during the rotor speed cycle. The online crack monitoring and analysis module (4) determines whether cracks have started during rotor speed cycling, specifically as follows: When the test rotor is subjected to low-cycle fatigue test, a flexible rotor is used. The maximum vibration peak generated during the rotor speed increase and decrease occurs at the critical speed position. After the speed increase exceeds the critical speed, the rotor automatically centers and the vibration decreases. If the rotor imbalance does not change, the maximum vibration amplitude value is stable. Therefore, two regular straight lines can be obtained for each cycle vibration peak and the corresponding speed. When a crack develops in the rotor, the crack will open under centrifugal load, causing the overall rotor imbalance to increase with the increase of rotational speed. The imbalance is greatest at the highest rotational speed, and the location of the maximum vibration amplitude changes from the critical speed to the highest rotational speed. During the transition, it can be observed that the location of the maximum vibration amplitude fluctuates between the critical speed and the maximum speed, and finally stabilizes at the maximum speed. When the online crack monitoring and analysis module detects that the location of the vibration peak fluctuates between the critical speed and the maximum speed, and eventually changes to the maximum speed, the online crack monitoring and analysis module determines that crack initiation has occurred in the rotor. The method for determining whether there is crack propagation during the rotor speed cycle in the online crack monitoring and analysis module (4) is as follows: after crack initiation, the online crack monitoring and analysis module finds that as the number of cycles increases, the vibration peak value of the rotor at the highest speed during each cycle speed-up process continuously increases. Then the online crack monitoring and analysis module determines that the initiated crack has propagated.

2. The online monitoring device for cracks in a vertical rotating test rotor according to claim 1, characterized in that, The online crack monitoring and analysis module (4) is equipped with a test safety module. When the peak value of the rotor vibration exceeds the first-level amplitude limit set by the tester, the online crack monitoring and analysis module issues a rotor abnormality alarm; when the peak value of the rotor vibration exceeds the second-level amplitude limit set by the tester, the online crack monitoring and analysis module triggers the test machine to stop for inspection.

3. The online monitoring device for cracks in a vertical rotating test rotor according to claim 1, characterized in that, The vibration sensor (2) is mounted on one side of the rotating spindle (1) via a sensor bracket, and the key phase sensor (6) is mounted on one side of the rotating spindle (1) via a sensor bracket.

4. A test method based on the online monitoring device for rotor cracks in a vertical rotating tester according to any one of claims 1-3, characterized in that, Includes the following steps: 1) Install the vibration sensor (2) on one side of the rotating spindle (1) through the sensor bracket, and install the key phase sensor (6) on one side of the rotating spindle (1) through the sensor bracket; the vibration sensor (2) determines the distance between the sensor probe and the object being measured by measuring the strength of the eddy current signal. By adjusting the radial gap between the vibration sensor (2) and the outer cylindrical surface of the rotating spindle (1), the vibration sensor can obtain a stable eddy current induction signal; the key phase sensor determines whether the sensor probe passes through or does not pass through the notch set on the rotating spindle by measuring the presence and disappearance of the electromagnetic induction signal. Adjust the gap between the key phase sensor (6) and the outer cylindrical surface of the rotating spindle (1) so that the key phase sensor can obtain a stable electromagnetic induction signal. Rotate the spindle slowly. When the notch on the spindle passes through the key phase sensor, the electromagnetic induction signal of the key phase sensor disappears. 2) Connect the vibration sensor (2) and the key phase sensor (6) to the signal processing module (3) of the online monitoring system respectively, and connect the signal processing module (3) of the online monitoring system to the online crack monitoring and analysis module (4); while the tester is rotating, connect and debug the sensor and signal transmission line until the sensor and signal transmission line can operate normally, and the online crack monitoring and analysis module (4) can complete the data recording and analysis work and normally display the curve of vibration amplitude changing with rotation speed; 3) Install the test rotor to the lower end of the drive shaft of the vertical rotary tester, turn on the power of the main unit of the vertical rotary tester, set the rotor outer diameter, axial height, weight, moment of inertia, target test speed and holding time, and then drive the test rotor from zero speed to accelerate to the target test speed and stabilize for 30 seconds before decelerating back to zero speed. This is to check whether the vibration sensor (2) and key phase sensor (6) are affected and fall off during the test rotor speed-up process, check and determine the critical speed and the maximum vibration amplitude when passing the critical speed, and record it. 4) Conduct online crack monitoring during the low-cycle fatigue test of the test rotor of the vertical rotary tester. Specifically, turn on the online crack monitoring and analysis module of the test rotor of the vertical rotary tester, input the rotor outer diameter, axial height, weight, and moment of inertia, set the upper limit speed, lower limit speed, holding time, and target total number of cycles, then drive the test rotor to increase the speed to the upper limit speed and hold time, then decrease the speed to the lower limit speed and hold time, and then continue to increase the speed to start the cycle with the same speed waveform until the target total number of cycles is reached and then stop the machine. When the online crack monitoring and analysis module detects that the location of the vibration peak fluctuates between the critical speed and the maximum speed, and eventually changes to the maximum speed, the online crack monitoring and analysis module determines that crack initiation has occurred in the rotor. After the crack initiation, the online crack monitoring and analysis module found that as the number of cycles increased, the vibration peak value of the rotor at the highest speed during each cycle of acceleration continuously increased. Therefore, the online crack monitoring and analysis module determined that the initiated crack had expanded. When the peak value of rotor vibration exceeds the first-level amplitude limit set by the tester, the online crack monitoring and analysis module issues a rotor abnormality alarm; when the peak value of rotor vibration exceeds the second-level amplitude limit set by the tester, the online crack monitoring and analysis module triggers the test machine to stop for inspection. After the test, the machine was stopped to check the location and length of crack initiation in the test rotor.

Images