A multi-frequency incremental eddy current image detection method for gear mechanical performance

Abstract

The application discloses a kind of multi-frequency increment eddy current image detection methods of gear mechanical properties, first, using the furnace sample of gear, prepare a batch of flat plate test pieces with different mechanical properties, using sensor provides mutually orthogonal low-frequency sinusoidal magnetic field (basic magnetic field) and stepped frequency modulation magnetic field (incremental magnetic field) to magnetize flat plate test piece, measure the multi-frequency increment eddy current image of all flat plate test pieces;Second, extract multiple characteristic parameters from multi-frequency increment eddy current image, establish their relationship equation with mechanical performance index;Finally, using sensor in gear body measured the characteristic parameter value of multi-frequency increment eddy current image, substitute into relationship equation to obtain the value of mechanical performance index.Based on the method, in-situ, on-line nondestructive testing of gear mechanical properties can be realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of non-destructive testing, and particularly relates to a multi-frequency incremental eddy current image detection method for gear mechanical properties, which can be extended to non-destructive testing of surface mechanical properties of ferromagnetic components. TECHNICAL BACKGROUND

[0002] Gear transmission mechanism is widely used in important fields such as automobiles, airplanes, aviation, etc., and the single product price is high, and the quality requirement is strict. At present, the material mechanical properties are mainly tested by furnace sample, which cannot accurately represent the actual mechanical properties of the gear. Therefore, it is urgent to develop a non-destructive testing method for the mechanical properties of the gear.

[0003] The microstructure of ferromagnetic material not only determines the mechanical properties of the material, but also determines the magnetic properties of the material. Many studies (for example, Ding S, Tian G, Sutthawe Ek Ul R. Non-destructive hardness prediction for 18CrNiMo7-6 steel based on feature selection and fusion of Magnetic Barkhausen Noise [J]. NDT&E international, 2019, 107 (Oct.): 102138.1-102138.8. Hiroaki, Kikuchi, Katsuyuki, et al. Characteristics of Barkhausen Noise Properties and Hysteresis Loop on Tensile Stressed Rolled Steels [J]. Journal of Magnetics, 2011.) show that the magnetic properties of the material can indirectly reflect the mechanical properties of the material. The measurement of the magnetic properties of the material can be carried out under non-contact and non-destructive conditions, and can be directly tested on the gear body. If the relationship between the magnetic properties and the mechanical properties can be calibrated by the furnace sample, the mechanical properties of the gear body can be non-destructively tested based on the magnetic property measurement method.

[0004] Based on this principle, a variety of mechanical performance nondestructive testing methods based on magnetic Barkhausen noise, tangential magnetic field strength, multi-frequency eddy current and incremental magnetic permeability have been developed. By proposing new magnetic property measurement methods, extracting new magnetic parameters sensitive to mechanical properties is the key direction in this field. The invention discloses a new magnetic property sensitive to mechanical properties-multiple frequency incremental eddy current image, and provides the corresponding detection method (including sensor form, magnetic field excitation and detection method) and feature parameter extraction method. The detection method of multi-frequency incremental eddy current image can be directly applied to the nondestructive testing of mechanical properties of gears and other ferromagnetic components. SUMMARY

[0005] The invention discloses a multi-frequency incremental eddy current image detection method for gear mechanical properties, which calibrates the relationship between multi-frequency incremental eddy current image and mechanical property index in advance, uses a micro-magnetic sensor to perform micro-magnetic nondestructive testing on a sample taken from the gear body, and converts the measured multi-frequency incremental eddy current image to obtain the mechanical property index value, wherein the feature parameter detection step of the multi-frequency incremental eddy current image is as follows:

[0006] Firstly, a low-frequency sinusoidal magnetic field and a step frequency magnetic field orthogonal to each other are used to magnetize the sample, wherein the frequency range and the intensity peak value range of the basic magnetic field are 10-500Hz and 10-50kA / m respectively, the frequency of the incremental magnetic field increases in a step form on the time axis, and the frequency range and the intensity peak value range are 10-500kHz and 2-100A / m respectively; secondly, the signal output by the sensor detection coil is subjected to time domain segmentation processing, and the real part and the imaginary part curves can be obtained after the signal is demodulated, and the center of gravity of each incremental eddy current ring is taken as a calibration point, and the calibration point is translated and rotated to form a cluster of "water drop-shaped" incremental eddy current rings; finally, the feature parameters of the multi-frequency incremental eddy current image are extracted, including: the geometric size W of the incremental eddy current ring, the maximum gradient D along the imaginary part and real part directions in the spatial gradient field of the multi-frequency incremental eddy current image, and the area Q under the curve of the change of the incremental eddy current ring surrounding area S with the incremental magnetic field frequency. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 : Low-frequency sinusoidal magnetic field (basic magnetic field) schematic diagram.

[0008] Figure 2 : Step frequency magnetic field (incremental magnetic field) schematic diagram.

[0009] Figure 3 : Step frequency mode schematic diagram.

[0010] Figure 4 : Detection sensor schematic diagram of multi-frequency incremental eddy current image.

[0011] Figure 5: Schematic diagram of multi-frequency incremental eddy current ring.

[0012] Figure 6 : Schematic diagram of spatial gradient of multi-frequency incremental eddy current image.

[0013] Figure 7 : Schematic diagram of curve of incremental eddy current ring surrounding area changing with incremental magnetic field frequency.

[0014] Figure 8 : Flow of incremental eddy current image detection method for gear mechanical performance. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical scheme and beneficial effects of the present application clearer, the embodiments of the present application are described in further detail below with reference to the drawings.

[0016] As shown in Figure 1 , it is a schematic diagram of low-frequency sinusoidal magnetic field (basic magnetic field). The frequency range and intensity peak value range of the basic magnetic field are 10-500 Hz and 10-50 kA / m, respectively.

[0017] As shown in Figure 2 , it is a schematic diagram of stepped frequency modulation magnetic field (incremental magnetic field). The frequency of the incremental magnetic field increases in a stepped form on the time axis, and the intensity peak value range is 2-100 A / m.

[0018] As shown in Figure 3 , it is a schematic diagram of stepped frequency modulation mode. Taking three periods of sinusoidal wave as one step, the frequency of the sinusoidal wave is sequentially and equally increased, and the frequency range is 10-500 kHz.

[0019] As shown in Figure 4 , it is a schematic diagram of detection sensor of multi-frequency incremental eddy current image. First, the host computer controls the signal generator and power amplifier circuit to output frequency and phase adjustable sinusoidal wave, and the excitation coil is connected to the alternating current signal to provide an external magnetic field to magnetize the measured component; second, the detection coil inputs the detected signal to the data acquisition card and displays it on the host computer; finally, the signal is processed to obtain the multi-frequency incremental eddy current ring signal.

[0020] As shown in Figure 5 , it is a schematic diagram of multi-frequency incremental eddy current ring. According to the frequency change step of the incremental magnetic field, the output signal of the sensor induction coil is processed in time domain, the real part and imaginary part curves of the signal are obtained by demodulation, and the center of gravity of each incremental eddy current ring is taken as the calibration point, which is translated and rotated to form a cluster of "water drop-shaped" incremental eddy current rings. By analyzing the change of the maximum value W of the real part and imaginary part of each incremental eddy current ring, the detection of the mechanical performance of the cast steel gear is realized.

[0021] As shown in Figure 6As shown in the figure, it is a schematic diagram of spatial gradient of multi-frequency incremental eddy current image. The maximum gradient D along the imaginary and real part directions in the spatial gradient field of multi-frequency incremental eddy current image changes with the change of the incremental magnetic field frequency. By analyzing the maximum gradient D along the imaginary and real part directions in the spatial gradient field, the detection of the mechanical properties of the cast steel gear is realized.

[0022] As shown in the figure, it is a schematic diagram of spatial gradient of multi-frequency incremental eddy current image. The maximum gradient D along the imaginary and real part directions in the spatial gradient field of multi-frequency incremental eddy current image changes with the change of the incremental magnetic field frequency. By analyzing the maximum gradient D along the imaginary and real part directions in the spatial gradient field, the detection of the mechanical properties of the cast steel gear is realized. Figure 7 As shown in the figure, it is a schematic diagram of the change curve of the incremental eddy current ring surrounding area with the change of the incremental magnetic field frequency. By analyzing the area Q under the change curve of the incremental eddy current ring surrounding area S with the change of the incremental magnetic field frequency, the detection of the mechanical properties of the cast steel gear is realized.

[0023] As shown in the figure, it is a schematic diagram of the change curve of the incremental eddy current ring surrounding area with the change of the incremental magnetic field frequency. By analyzing the area Q under the change curve of the incremental eddy current ring surrounding area S with the change of the incremental magnetic field frequency, the detection of the mechanical properties of the cast steel gear is realized. Figure 8 As shown in the figure, it is a flow chart of the incremental eddy current image detection method of gear mechanical properties. First, a batch of flat test pieces with different mechanical properties are prepared by using the furnace test sample of the gear. Second, the multi-frequency incremental eddy current images of all flat test pieces are measured by using the sensor. Third, a plurality of characteristic parameters are extracted from the multi-frequency incremental eddy current images, and a relationship equation between them and the mechanical performance index is established. Finally, the characteristic parameter values of the multi-frequency incremental eddy current image measured by the sensor in the gear body are substituted into the relationship equation to calculate the value of the mechanical performance index.

Claims

1. A method for detecting gear mechanical properties using multi-frequency incremental eddy current images, characterized in that, The sensitivity of multi-frequency incremental eddy current images of ferromagnetic materials to changes in mechanical properties is utilized. By pre-calibrating the relationship between multi-frequency incremental eddy current images and mechanical performance indicators, the mechanical performance indicator values ​​are obtained by converting multi-frequency incremental eddy current images directly measured from the gear body in a non-destructive manner. The feature parameter detection steps of the multi-frequency incremental eddy current images are as follows: 1) The material is magnetized by a low-frequency sinusoidal magnetic field and a stepped frequency-modulated magnetic field that are orthogonal to each other in space. The directions of the basic magnetic field and the incremental magnetic field are parallel to and perpendicular to the surface of the specimen, respectively. The frequency range and peak intensity range of the basic magnetic field are 10-500 Hz and 10-50 kA / m, respectively. The frequency of the incremental magnetic field increases in a stepwise manner on the time axis, with a frequency range of 10-500 kHz and a peak intensity range of 2-100 A / m, respectively. 2) Based on the frequency change step of the incremental magnetic field, the output signal of the sensor induction coil is processed in the time domain. The real and imaginary part curves of the signal are obtained by demodulation. The centroid of each incremental eddy current ring is used as the calibration point and translated and rotated to form a cluster of "teardrop-shaped" incremental eddy current rings, which is the multi-frequency incremental eddy current image. 3) The feature parameters extracted from the multi-frequency incremental eddy current image include: the geometric dimensions W of the "teardrop-shaped" incremental eddy current ring along the imaginary and real directions, the maximum gradient D along the imaginary and real directions in the spatial gradient field of the multi-frequency incremental eddy current image, and the area Q below the curve of the area S enclosed by the incremental eddy current ring as a function of the frequency of the incremental magnetic field.

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