Method and device capable of non-destructively evaluating electromagnetic strengthening effectiveness of bearing

Abstract

The invention discloses a method and a device capable of non-destructively evaluating bearing electromagnetic strengthening effectiveness, and belongs to the field of bearing electromagnetic strengthening. Respectively and coaxially placing independent parts of the bearing outer ferrule and the bearing inner ferrule outside and inside the detection coil, introducing sine wave current, and detecting a real part and an imaginary part of the impedance of the coil; and meanwhile, respectively comparing the impedance real part and imaginary part of the bearing component which is detected by the same method and is not subjected to electromagnetic strengthening completely and the impedance real part and imaginary part of the bearing component which is subjected to electromagnetic strengthening. By detecting the change of the impedance of the coil, whether the coil is subjected to electromagnetic strengthening treatment or not is distinguished, all bearing parts in the same batch can be detected, and the method has the advantages of no contact, high efficiency, easiness in implementation and low cost.

Description

Technical Field

[0001] The invention belongs to the field of electromagnetic strengthening of bearings, and in particular relates to a method and a device for non-destructively evaluating the effectiveness of electromagnetic strengthening of bearings. Background Art

[0002] Bearings are indispensable parts in aircraft engines. With the improvement of the thrust-to-weight ratio of aircraft engines, the service environment of bearings has become more demanding, and the requirements for their service performance have become higher and higher. Electromagnetic strengthening technology has been proven to improve the wear resistance and fatigue life of bearings, but the effectiveness of strengthening is currently mainly evaluated through mechanical property tests at the material level and random sampling simulated working condition bench tests. Both methods are destructive and inefficient, and there is a lack of non-destructive and efficient evaluation methods for aircraft engine bearings.

[0003] At present, there are two main ways to evaluate the effectiveness of electromagnetic strengthening of bearings: one is microstructure characterization represented by electron backscatter diffraction, and the other is mechanical property testing represented by friction and wear tests. Both of the above methods are destructive to a certain extent, so they are only applicable to the material level. There is a lack of efficient and non-destructive evaluation methods for aircraft engine bearings with strict reliability requirements.

[0004] Electromagnetic strengthening technology regulates the microstructure of bearing materials through "magnetic phase transition" and "magnetic plasticity" to achieve the purpose of improving its mechanical properties. The electrical conductivity of metal materials is extremely sensitive to changes in their composition and microstructure. Therefore, changes in the electrical conductivity of materials can be used to analyze changes in the internal structure of the material and infer changes in its mechanical properties.

[0005] There are two main ways to test the electrical conductivity of existing metal materials:

[0006] (1) DC four-probe method

[0007] The DC four-probe method is mainly composed of metal probes, current source and potential difference meter. During measurement, the four probes can be arranged in a row with unequal spacing, with the outer side being the current probe and the inner side being the voltage probe. A small current is input by the current source to generate a voltage drop inside the sample. At the same time, a high-impedance electrometer, electronic millivoltmeter or digital voltmeter is used to measure the voltage between the voltage probes. The resistivity of the material is calculated based on the voltage, current, and probe spacing.

[0008] (2) Ultrasonic testing method

[0009] The material resistivity measuring device based on ultrasonic testing technology is mainly composed of a low-frequency signal generator, an oscilloscope, an ultrasonic transducer, and a material fixing device. The transmitting end of the ultrasonic transducer converts the sine wave signal of the low-frequency signal generator into an ultrasonic signal, and the receiving end converts the ultrasonic signal into an electrical signal and inputs it into the oscilloscope to display the Lissajous figure of the material. The change in the material's conductive properties is calculated based on the periodic changes in the Lissajous figure.

[0010] The existing technology has shortcomings and problems:

[0011] 1. The probe of the DC four-probe method needs to contact the sample surface, which is greatly affected by the contact force and the probe tip diameter, and the measurement repeatability is poor.

[0012] 2. Measuring high-resistance materials requires passing a large current, which can easily cause the sample to heat up and introduce measurement errors.

[0013] 3. The ultrasonic detection system is relatively complex and expensive, inconvenient to operate and inefficient.

[0014] The present invention proposes a method and a device for distinguishing whether an aero-engine bearing has undergone a qualified electromagnetic strengthening treatment by using the change of the detection coil impedance as a criterion.

[0015] When an alternating current is passed through the detection coil, an alternating primary magnetic field will be generated around the coil; since the intensity of the magnetic field changes over time, according to Faraday's law of electromagnetic induction, induced eddy currents will be generated in the bearing components in the primary magnetic field, and a secondary magnetic field with a direction opposite to the primary magnetic field will also be generated around the bearing components. When the electrical conductivity of the material used to make the bearing changes, the distribution and intensity of the eddy current will also change, and the intensity of the secondary magnetic field will also change. Changes in the secondary magnetic field will affect the primary magnetic field, thereby causing changes in the current or induced voltage in the detection coil, which is manifested as changes in the impedance of the detection coil. By accurately measuring the changes in the impedance of the detection coil through instruments and analyzing the measurement data, it can be inferred whether the surface or near-surface of the bearing component has been subjected to electromagnetic strengthening treatment. Summary of the invention

[0016] The above principle of the present invention provides a method for non-destructively evaluating the effectiveness of electromagnetic strengthening treatment of aircraft engine bearings, and the specific steps are as follows:

[0017] (1) Select a detection coil of appropriate size according to the structure and geometric dimensions of the bearing component to be tested;

[0018] (2) Clean the bearing components to be tested to ensure that there is no other conductive material on the surface;

[0019] (3) Use a 4-terminal Kelvin clamp to connect the two pins of the detection coil to the four interfaces of the digital bridge tester, with the two high-potential interfaces corresponding to one pin and the two low-potential interfaces connected to another pin;

[0020] (4) Place the bearing component to be tested into the detection coil, keep it coaxial with the detection coil, and fit the lower end surface of the bearing component with the upper end surface of the boss of the detection coil skeleton;

[0021] (5) According to the detection requirements, input a current with a frequency of 1 Hz to 200 kHz, an amplitude of 0.01 mA to 1 A, and a sinusoidal waveform; when the current is passed through the detection coil, record the real and imaginary parts of the detection coil impedance measured by the digital bridge tester;

[0022] (6) After the same bearing component to be tested is subjected to electromagnetic strengthening treatment, the above steps (4) to (5) are repeated to obtain the real part 1 and the imaginary part 1 of the detection coil impedance after electromagnetic strengthening; the above steps (4) to (5) are repeated for the same bearing component that has not been subjected to any electromagnetic strengthening to obtain the real part 2 and the imaginary part 2 of the detection coil impedance after electromagnetic strengthening;

[0023] (7) comparing the real and imaginary parts of the impedance corresponding to the bearing component to be tested obtained in step (5) with the real and imaginary parts 1 and 1 and the real and imaginary parts 2 and 2, respectively, and the one that is closer to the real and imaginary parts corresponds to electromagnetic enhancement or non-electromagnetic enhancement;

[0024] The electromagnetic parameters of the electromagnetic enhancement of the specific pair of coil impedance real part 1 and imaginary part 1 can be set to multiple different quantities as needed to obtain different impedance real parts 1 and imaginary parts 1, and the corresponding closest real and imaginary impedance parts obtained in step (5) are found.

[0025] The device used to implement the above method comprises a signal transmitter (1), a power amplifier (2), a multi-channel system (3), a detection coil (4), an outer bearing ring (5), an inner bearing ring (6), a signal receiver (7), and a computer system (8); the signal transmitter (1) is electrically connected to the multi-channel system (3) via the power amplifier (2), the multi-channel system (3) is electrically connected to the detection coil (4), the multi-channel system (3) is also electrically connected to the signal receiver (7), and the signal receiver (7) is electrically connected to the computer system (8); the functions of the signal transmitter (1), the power amplifier (2), the multi-channel system (3), and the signal receiver (7) are implemented using a digital bridge tester.

[0026] The detection coil (4) is an independent coil of a wound spring structure, and the inner and outer sides of the detection coil (4) are encapsulated by an insulating hard material; the inner and outer insulating hard encapsulations are the inner and outer frames of the coil, and the inner frame of the detection coil (4) is provided with a circle of protrusions, which is recorded as the inner protrusion, and the outer frame of the detection coil (4) is provided with a circle of protrusions, which is recorded as the outer protrusion;

[0027] The outer bearing ring (5) and the inner bearing ring (6) are independent components of the bearing. During testing, the outer bearing ring (5) is coaxially located outside the detection coil (4), and the lower end surface of the outer bearing ring (5) is supported by an outer protrusion. The inner bearing ring (6) is coaxially located inside the detection coil (4), and the lower end surface of the inner bearing ring (6) is supported by an inner protrusion, so that the outer bearing ring (5) and the inner bearing ring (6) correspond to each other inside and outside.

[0028] The detection method is implemented through a digital bridge tester and a detection coil, where the detection coil needs to be customized according to the actual specifications and dimensions of the bearing component being tested. By detecting the change in the impedance of the detection coil to distinguish whether it has undergone electromagnetic strengthening treatment, all bearing components in the same batch can be tested. The advantages of this method are non-contact, high efficiency, easy implementation and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the detection device of the present invention;

[0030] Among them, 1-signal transmitter; 2-power amplifier; 3-multi-channel system; 4-annular copper coil (axial section); 5-signal receiver; 6-computer system.

[0031] Figure 2 It is a structural schematic diagram of the positional relationship between the outer bearing ring, the inner bearing ring, and the detection coil;

[0032] Figure 3 This is a diagram of the actual detection device.

[0033] Figure 4 This is an actual diagram of the matching of the outer bearing ring, inner bearing ring and detection coil. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with examples, but the present invention is not limited to the following examples.

[0035] Embodiment 1:

[0036] A detection coil with a height of 40mm and an inner diameter of 11mm was selected, and a sine wave current with a frequency of 10kHz and an amplitude of 1mA was passed through to detect the GCr15 bearing steel cylindrical rollers with a diameter of 10mm×35mm produced in the same batch. When a cylindrical roller that has not been electromagnetically strengthened is placed in the detection coil, the real part of the impedance of the detection coil is 29.3285±0.0718Ω, and the imaginary part of the impedance is 47.3223±0.1236Ω. When a cylindrical roller that has been electromagnetically strengthened with a magnetic field strength of 0.8T, a frequency of 1Hz, and a waveform of a half-sine wave is placed in the detection coil, the real part of the impedance of the detection coil is 29.0547±0.0411Ω, and the imaginary part of the impedance is 46.4467±0.0664Ω. If a cylindrical specimen of unknown state is placed, the impedance measurement result of the detection coil is closer to the real and imaginary impedance of the detection coil when a cylindrical roller that has not been electromagnetically strengthened is placed, which means that the cylindrical roller has not been electromagnetically strengthened or the effect of the electromagnetic strengthening treatment is not good; otherwise, it means that the cylindrical roller has undergone qualified electromagnetic strengthening treatment.

[0037] Embodiment 2:

[0038] A detection coil with a height of 65mm and a center radius of 20.5mm in the coil section was selected, and a sine wave current with a frequency of 200kHz and an amplitude of 0.05mA was passed to detect the inner and outer rings of the same batch of NU1006 bearings made of M50 bearing steel. When the inner and outer rings of the NU1006 bearings that had not been electromagnetically strengthened were placed in the detection coil, the real part of the impedance of the detection coil was 142.5824±0.2632Ω and 135.593±0.3123Ω respectively. When the inner and outer rings of the NU1006 bearings that had been electromagnetically strengthened with a magnetic field strength of 0.8T, a frequency of 1Hz, and a waveform of a half-sine wave were placed in the detection coil, the real part of the impedance of the detection coil was 139.6243±0.137Ω and 132.9299±0.2567Ω respectively. If an unknown state of the NU1006 bearing inner ring and outer ring are placed, the real part of the detection coil impedance is closer to the real part of the detection coil impedance when the NU1006 bearing inner ring and outer ring that have not been electromagnetically strengthened are placed, which means that the cylindrical roller has not been electromagnetically strengthened or the effect of the electromagnetic strengthening treatment is not good; otherwise, it means that the NU1006 bearing inner ring and outer ring have undergone qualified electromagnetic strengthening treatment.

Claims

1. A method for non-destructively evaluating the effectiveness of electromagnetic strengthening treatment of aircraft engine bearings, characterized in that: The specific steps are as follows: (1) Select a detection coil of appropriate size according to the structure and geometric dimensions of the bearing component to be tested; (2) Clean the bearing components to be tested to ensure that there is no other conductive material on the surface; (3) Use a 4-terminal Kelvin clamp to connect the two pins of the detection coil to the four interfaces of the digital bridge tester, with the two high-potential interfaces corresponding to one pin and the two low-potential interfaces connected to another pin; (4) Place the bearing component to be tested into the detection coil, keep it coaxial with the detection coil, and fit the lower end surface of the bearing component with the upper end surface of the boss of the detection coil skeleton; (5) According to the detection requirements, input a current with a frequency of 1 Hz to 200 kHz, an amplitude of 0.01 mA to 1 A, and a sinusoidal waveform; when the current is passed through the detection coil, record the real and imaginary parts of the detection coil impedance measured by the digital bridge tester; (6) After the same bearing component to be tested is subjected to electromagnetic strengthening treatment, the above steps (4) to (5) are repeated to obtain the real part 1 and the imaginary part 1 of the detection coil impedance after electromagnetic strengthening; the above steps (4) to (5) are repeated for the same bearing component that has not been subjected to any electromagnetic strengthening to obtain the real part 2 and the imaginary part 2 of the detection coil impedance after electromagnetic strengthening; (7) The real and imaginary parts of the impedance corresponding to the bearing component to be tested obtained in step (5) are compared with the real and imaginary parts of the impedance 1 and 1, and the real and imaginary parts of the impedance 2 and 2, respectively. The one that is closer to the real and imaginary parts corresponds to electromagnetic enhancement or non-electromagnetic enhancement.

2. The method according to claim 1, characterized in that The electromagnetic parameters of the electromagnetic enhancement of the specific pair of coil impedance real part 1 and imaginary part 1 can be set to multiple different quantities as needed to obtain different impedance real parts 1 and imaginary parts 1, and the corresponding closest real and imaginary impedance parts obtained in step (5) are found.

3. The method according to claim 1, characterized in that The device used comprises a signal transmitter (1), a power amplifier (2), a multi-channel system (3), a detection coil (4), an outer bearing ring (5), an inner bearing ring (6), a signal receiver (7), and a computer system (8); the signal transmitter (1) is electrically connected to the multi-channel system (3) via the power amplifier (2), the multi-channel system (3) is electrically connected to the detection coil (4), the multi-channel system (3) is also electrically connected to the signal receiver (7), and the signal receiver (7) is electrically connected to the computer system (8); the functions of the signal transmitter (1), the power amplifier (2), the multi-channel system (3), and the signal receiver (7) are realized by using a digital bridge tester.

4. The method according to claim 3, characterized in that The detection coil (4) is an independent coil of a wound spring structure, and the inner and outer sides of the detection coil (4) are encapsulated by an insulating hard material; the inner and outer insulating hard encapsulations are the inner and outer frames of the coil, and the inner frame of the detection coil (4) is provided with a circle of protrusions, which is recorded as the inner protrusion, and the outer frame of the detection coil (4) is provided with a circle of protrusions, which is recorded as the outer protrusion; The outer bearing ring (5) and the inner bearing ring (6) are independent components of the bearing. During testing, the outer bearing ring (5) is coaxially located outside the detection coil (4), and the lower end surface of the outer bearing ring (5) is supported by an outer protrusion. The inner bearing ring (6) is coaxially located inside the detection coil (4), and the lower end surface of the inner bearing ring (6) is supported by an inner protrusion, so that the outer bearing ring (5) and the inner bearing ring (6) correspond to each other inside and outside.

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