CN116448873A - Eddy current flaw detector and method capable of detecting conductor ultrafine wire cracks - Google Patents
Eddy current flaw detector and method capable of detecting conductor ultrafine wire cracks Download PDFInfo
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Abstract
The invention discloses an eddy current flaw detector and method capable of detecting conductor ultrafine wire cracks, comprising the following steps: the output end of the resonance generator is connected to the transmitting end of the detection probe to form a 1-40MHz resonance frequency detection source, and the detection source generates induced current on the surface of the material to be detected when approaching the material to be detected; the receiving end of the detection probe is connected to the input end of the signal conversion module and is used for receiving a resonant frequency signal returned by the material to be detected, and the detection probe changes according to the induced current of the material to be detected so as to generate resonant frequency change; the signal conversion module converts the resonance frequency signal generated by the detection probe into a voltage signal, and the output end of the signal conversion module is connected to the recording analysis module and is used for recording and analyzing the voltage signal in real time to realize flaw detection of the material to be detected. The detection of the very fine broken wire cracks can be realized.
Description
Technical Field
The invention relates to the technical field of eddy current flaw detection, in particular to an eddy current flaw detector and an eddy current flaw detection method capable of detecting conductor ultrafine wire flaws.
Background
The eddy current flaw detector is a device for detecting whether the defects of cracks, air holes and the like exist in steel bars and plates based on an eddy current detection principle, has the functions of inhibiting interference signals and picking up useful information, and consists of an oscillation generator, a detection probe, a signal conversion module, a recording analysis module and the like, and is mainly used for nondestructive flaw detection of metal materials.
The eddy current inspection principle uses the principle of electromagnetic induction. When alternating current is passed into a coil, if the voltage and frequency are unchanged, the current through the coil will also be unchanged. If there is a conductor near the coil, an induced current is generated at the surface of the conductor, which is called an eddy current because the induced current is a whirlpool generated by the rotating coil, particularly like water. The eddy current magnetic field is opposite to the applied current, so that the impedance of the coil and the phase of the passing current are changed. If other factors are kept unchanged, when defects exist on the surface or the subsurface of the conductor, parameters such as current, impedance and the like of the coil are affected. The signal output of the change caused by the defect is amplified, so that the purpose of flaw detection can be achieved.
The detection probe contains a coil inside that functions as a sensing element, and any defect modulates the high frequency carrier (excitation) signal when the sensor probe is used to scan and detect a workpiece. Eventually, any characteristic (e.g., material conductivity or permeability) or any defect present that would affect the detection of the eddy current state inside the metal workpiece will be displayed on the eddy current signal curve. For example, as shown in fig. 1, when a crack occurs, the magnitude of the ac voltage across the detection probe coil temporarily increases.
The traditional flaw detector is obtained by outputting a certain excitation frequency signal and analyzing the impedance change of the signal, and the frequency is limited to be not more than 10MH, so that the detection of the extremely fine wire cracks is not attractive.
Disclosure of Invention
In view of the above, an object of the present invention is to provide an eddy current flaw detector and a method capable of detecting a crack in a conductor microfilament, which can solve the above-mentioned problems.
In one aspect, the present invention provides an eddy current flaw detector for detecting a crack in a conductor microfilament, comprising: the device comprises a resonance generator, a detection probe, a signal conversion module and a recording analysis module;
the output end of the resonance generator is connected to the transmitting end of the detection probe to form a 1-40MHz resonance frequency detection source, and the detection source generates induced current on the surface of the material to be detected when approaching the material to be detected;
the receiving end of the detection probe is connected to the input end of the signal conversion module and is used for receiving a resonant frequency signal returned by the material to be detected, and the detection probe changes according to the induced current of the material to be detected so as to generate resonant frequency change; the detection probe includes: flaw detection signal acquisition coil, interference signal compensation coil and comparator I1; the flaw detection signal acquisition coil is connected to the positive electrode of the comparator I1 and is used for transmitting and acquiring resonance frequency; the interference signal compensation coil is connected to the negative electrode of the comparator I1 and is used for generating a differential compensation signal so as to counteract external interference signals when receiving resonance frequency signals; the output end of the comparator I1 is connected to the input end of the signal conversion module;
the signal conversion module converts a resonance frequency signal generated by the detection probe into a voltage signal, and the signal conversion module comprises: a frequency dividing circuit and a frequency-voltage converting circuit; the input end of the frequency dividing circuit is connected to the receiving end of the detection probe and is used for dividing the frequency of the resonant frequency signal; the output end of the frequency dividing circuit is connected to the input end of the frequency-voltage conversion circuit and is used for converting the resonance frequency signal into a voltage signal; the output end of the signal conversion module is connected to the recording analysis module and is used for recording and analyzing the voltage signal in real time to realize flaw detection of the material to be detected.
Further, the method comprises the steps of: zero compensation circuit and digital display DC voltmeter;
the zero compensation module is connected to the output end of the signal conversion module and used for adjusting the output voltage and the calibration reference voltage; the input end of the digital display direct current voltmeter is connected to the output end of the signal conversion module and used for displaying the current output voltage and matching with the zero compensation circuit to calibrate the reference voltage.
Further, the method comprises the steps of: a DC amplifying circuit;
the output end of the zero compensation circuit is connected to the input end of the direct current amplifying circuit and used for amplifying voltage signals.
Further, the method comprises the steps of: a voltage follower circuit;
the input end of the voltage follower circuit is connected to the output end of the direct current amplifying circuit, and the output end of the voltage follower circuit is connected to the input end of the recording analysis module and used for buffering and isolating the input voltage of the direct current amplifying circuit.
Further, the method comprises the steps of: roller type meter counter;
the output end of the roller type meter counting counter is connected to the input end of the recording analysis module and used for calculating the length of the material to be measured and sending the length to the recording analysis module and the voltage signal to synchronously record.
In another aspect, the present invention provides an eddy current flaw detection method for detecting cracks in a conductor microfilament, comprising:
generating the resonance frequency signal through the resonance generator and sending the resonance frequency signal to the material to be detected through the detection probe;
the detection probe generates a change according to the induced current of the material to be detected so as to generate a resonance frequency change, and the resonance frequency signal is obtained;
converting all the resonant frequency signals into the voltage signals by the signal conversion module;
correspondingly recording the voltage signal according to the length of the material to be measured through the recording analysis module;
and analyzing and calculating the voltage signal through the record analysis module to obtain crack depths of different positions of the material to be tested.
Further, the converting, by the signal conversion module, all of the resonant frequency signals into the voltage signals includes:
performing frequency division processing on all the resonant frequency signals for 6 times through the frequency division circuit to obtain frequency division signals;
the frequency-divided signal is converted into the voltage signal by the frequency-voltage conversion circuit.
Further, the recording, by the recording analysis module, the voltage signal according to the length of the material to be measured includes:
the roller type meter counter moves along with the detection probe;
synchronously transmitting the moving meter number to the record analysis module through the roller meter counter;
and synchronously transmitting the voltage signal to the record analysis module through the signal conversion module.
Further, the step of analyzing and calculating the voltage signal by the recording and analyzing module to obtain crack depths L of different positions of the material to be measured includes:
acquiring the diameter D, full-range voltage U and amplified voltage signal Uo of the material to be measured;
and calculating the crack depth L according to the diameter D of the material to be detected, the full-range voltage U and the amplified voltage signal Uo, wherein the crack depth L=DxU0/U is satisfied.
Further, the generating the resonance frequency signal by the resonance generator before the sending the resonance frequency signal through the detection probe comprises:
and carrying out zero setting calibration on the voltage signal output by the signal conversion module through the zero point compensation circuit.
The invention has the beneficial effects that:
firstly, a sine wave with the frequency of 1-40MHz is generated by a resonance generator, and then the frequency division circuit, the frequency-voltage conversion module and the direct current amplification circuit are matched, so that the frequency division conversion processing is carried out on resonance frequency signals with the frequency of 1-40MHz and above, weak signals are amplified, the detection sensitivity is further improved, and cracks below 10 microns can be detected.
Secondly, a self-excited oscillation signal is generated through a feedback type LC oscillator of the common base transformer, the excitation frequency of the original signal is broken through, an impedance change signal is analyzed to obtain a flaw detection signal, and the flaw detection signal is obtained through the frequency change signal caused by the impedance change by using a resonant circuit principle.
Thirdly, setting a flaw detection signal acquisition coil and an interference signal compensation coil in the detection probe; the flaw detection signals are collected in the same detection coil, so that errors caused by difference of two probes in standard comparison are avoided. Meanwhile, the two coils are placed in the same probe, the obtained interference signals are certainly consistent, and the two coils form differential compensation type, so that the interference signals are counteracted in real time, and the anti-interference performance is obviously enhanced.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a flaw detector in the background of the invention.
FIG. 2 is a schematic diagram showing the constitution of a flaw detector according to the present invention.
Fig. 3 is a diagram of an LC parallel resonant circuit in the present invention.
Fig. 4 is a diagram of a feedback LC tank circuit of the common base transformer in the present invention.
Fig. 5 is a schematic diagram of a standard comparative test probe structure in the present invention.
Fig. 6 is a schematic structural diagram of a conventional absolute type detection probe in the present invention.
FIG. 7 is a schematic view of the structure of the improved inspection probe of the present invention.
Fig. 8 is a circuit diagram of frequency-to-voltage conversion in the present invention.
Fig. 9 is a zero point compensation circuit diagram in the present invention.
Fig. 10 is a dc amplifying circuit diagram in the present invention.
Fig. 11 is a voltage follower circuit diagram in the present invention.
FIG. 12 is a voltage chart of the flaw detection result in the present invention.
FIG. 13 is a comparison of the flaw detection results of the flaw detector and the metallographic examination in the case of a flaw in the present invention.
FIG. 14 is a comparison of the flaw detection results of the flaw detector and the metallographic examination in the case of no flaw in the present invention.
Detailed Description
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
As shown in fig. 2, an embodiment of the present invention provides an eddy current flaw detector capable of detecting a crack of a conductor microfilament, comprising: the device comprises a resonance generator, a detection probe, a signal conversion module and a recording analysis module;
the output end of the resonance generator is connected to the transmitting end of the detection probe to form a 1-40MHz resonance frequency detection source, and the detection source generates induced current on the surface of the material to be detected when approaching the material to be detected;
in this embodiment, there are four schemes for designing the signal source:
1. directly generating by using a special DDS chip; the scheme has the advantages that: the high-stability and high-precision signal can be output, the sine wave with the frequency ranging from 0Hz to 10MHz can be easily generated, and the frequency can be easily changed; the disadvantage of this solution is: it is difficult to generate a sine wave of a frequency of 10MHz or more.
2. The integrated chips such as FPGA and the like are synthesized by DDS technology; the scheme has the advantages that: the frequency source with high stability and high precision can be output, the sine wave can be easily output, and the frequency can be easily changed; the disadvantage of this solution is: it is difficult to generate a sine wave of a frequency of 100kHz or more;
3. generating by using a resonant circuit; the scheme has the advantages that: the circuit has a simple structure and is easy to generate sine waves with the frequency ranging from 0Hz to 50 MHz; the disadvantage of this solution is: it is difficult to change the frequency.
4. Generating a square wave with required frequency by using a crystal oscillator and a frequency divider, and converting the square wave into a sine wave by a filter; the scheme has the advantages that: sine waves with the frequency ranging from 0Hz to 10MHz are easy to generate; the disadvantage of this solution is: it is difficult to generate a sine wave having a frequency of 10MHz or more and to change the frequency.
Because the frequency value of the signal source is required to be higher in the design, the scheme 3 is easier to realize the frequency of 40MHz, so that the scheme 3 is selected, and the signal source is realized by adopting a resonance generator.
As shown in fig. 3, the LC parallel resonant circuit is an oscillating circuit formed by connecting an inductance coil L, a capacitor C and an external signal source in parallel. Under the signal excitation of different working frequencies, the LC parallel resonant circuit shows different impedance amplitude-frequency characteristics and phase-frequency characteristics. Wherein r represents the equivalent loss resistance of the coil L, and the equivalent impedance is a pure resistance according to the resonance of the loop, so as to obtain the resonanceFrom this, the resonance frequency +.>Or->
Further, as shown in fig. 4, the present invention adopts a common base transformer feedback LC oscillator as a resonance generator, and in such a feedback oscillator circuit, a feedback voltage is used as an input voltage, and an LC parallel resonant loop is mainly used as a frequency-selective feedback network. The signal of the output end is fed back to the input end, and the feedback signal and the input signal have the same phase to form a closed loop positive feedback, so that the output signal can be generated without external signal excitation, and self-oscillation is generated.
The receiving end of the detection probe is connected to the input end of the signal conversion module and is used for receiving a resonant frequency signal returned by the material to be detected, and the detection probe changes according to the induced current of the material to be detected so as to generate resonant frequency change; the detection probe includes: flaw detection signal acquisition coil, interference signal compensation coil and comparator I1; the flaw detection signal acquisition coil is connected to the positive electrode of the comparator I1 and is used for transmitting and acquiring resonance frequency; the interference signal compensation coil is connected to the negative electrode of the comparator I1 and is used for generating a differential compensation signal so as to counteract external interference signals when receiving resonance frequency signals; the output end of the comparator I1 is connected to the input end of the signal conversion module;
in the present embodiment, in the eddy current flaw detection, an alternating magnetic field is established by a detection probe (detection coil) to transfer energy to a conductor to be inspected; meanwhile, the quality information in the detected conductor is obtained through the alternating magnetic field established by the eddy current. Thus, the detection coil is effectively a transducer.
The standard comparative type (shown in fig. 5) can identify continuous cracks and penetrating cracks, but has poor tamper resistance. Analysis reasons show that since the two probes are independent, when one probe obtains an interference signal and the other probe does not obtain the interference signal, the bridge is out of balance, so that inspection errors are caused. The scheme has high requirements on consistency of two probes and consistency and shielding performance of probe wires, and is difficult in the actual operation process.
Conventional absolute (as shown in fig. 6) probes have only one coil, and although they can identify continuity cracks and penetration cracks, they have poor interference resistance. The analysis causes that, since it has only one probe, when it gets an interference signal, the bridge is out of balance, causing an inspection error. This solution is particularly demanding in terms of shielding, which is also difficult during practical operation.
Thus, the invention improves the absolute type of combination, two coils are placed in the same probe, one for flaw detection signal acquisition and one for interference signal compensation (as shown in figure 7). Such probes have two characteristics:
1. the flaw detection signals are collected in the same detection coil, so that errors caused by difference of two probes in standard comparison are avoided.
2. The two coils are placed in the same probe, the obtained interference signals are certainly consistent, and the two coils form differential compensation type, so that the interference signals are counteracted in real time, and the anti-interference performance is obviously enhanced.
The signal conversion module converts a resonance frequency signal generated by the detection probe into a voltage signal, and the signal conversion module comprises: a frequency dividing circuit and a frequency-voltage converting circuit; the input end of the frequency dividing circuit is connected to the receiving end of the detection probe and is used for dividing the frequency of the resonant frequency signal; the output end of the frequency dividing circuit is connected to the input end of the frequency-voltage conversion circuit and is used for converting the resonance frequency signal into a voltage signal; the output end of the signal conversion module is connected to the recording analysis module and is used for recording and analyzing the voltage signal in real time to realize flaw detection of the material to be detected.
In this embodiment, the signal output by the resonance generator is detected by flaw detection to cause a small change in resonance frequency, and the frequency signal indicating the change of the signal is corresponding to the flaw as the flaw increases, so the invention only needs to extract the frequency signal. Because the change proportion of the frequency signal is fixed, the change proportion is unchanged after frequency division. The frequency required to be converted in the invention is up to 40MHz, the highest frequency of the frequency-voltage conversion chip in the market is 2MHz of AD652, and the analysis of 40MHz is required and special treatment is also required. Because the change proportion of the frequency signal is fixed and is unchanged after frequency division, the invention divides the frequency of the frequency division chip CD4024 into 0.625MHz after frequency division is carried out for 6 times by frequency division processing on the high-frequency signal, and thus the mature frequency-voltage conversion chip can be directly used for directly converting the signal as shown in figure 8.
Further, the method comprises the steps of: zero compensation circuit and digital display DC voltmeter;
the zero compensation module is connected to the output end of the signal conversion module and used for adjusting the output voltage and the calibration reference voltage; the input end of the digital display direct current voltmeter is connected to the output end of the signal conversion module and used for displaying the current output voltage and matching with the zero compensation circuit to calibrate the reference voltage.
In the embodiment, the invention adopts the small three-position half LCD liquid crystal digital display direct current voltmeter to directly display the voltage value, is more visual and is convenient to directly read the voltage value during calibration. The zero compensation circuit makes the output voltage approach zero through the addition and subtraction circuit. As shown in fig. 9, its output voltage uo=ui1-Ui 2.
Further, the flaw detector is calibrated by using a zero compensation circuit and a digital display direct current voltmeter as follows:
1. firstly, a section of standard sample is selected, the standard sample can be selected from actual materials, and crack-free materials can also be subjected to laser engraving. The standard requires a length of around 200mm, where 100mm is a crack-free segment and the other 100mm is a crack segment. The crack depth of the actual material can be obtained through metallographic observation, and the crack depth engraved by laser can be measured through a microscope.
2. After the depth of the crack segment is confirmed, a corresponding standard voltage value can be calculated, and the calculation formula is as follows:
standard voltage value = 5V x crack depth +.filament diameter;
for example: a wire with a diameter of 0.2mm and a crack depth of 0.04mm, the standard voltage value=5v×0.04++0.2=1v;
3. penetrating a crack-free section of a standard sample into a detection probe, rotating a zero-setting knob to adjust the voltage value to about 0V, penetrating the crack section into the detection probe, reading the voltage value, and if the voltage value is lower than a standard value, rotating the zero-setting knob clockwise to adjust the voltage value to the standard value; if the voltage value is higher than the standard value, rotating the zero-setting knob anticlockwise; and detecting the crack-free section after the voltage value is calibrated, and confirming whether the voltage value is near 0V or not, if so, completing the calibration.
Further, the method comprises the steps of: a DC amplifying circuit;
the output end of the zero compensation circuit is connected to the input end of the direct current amplifying circuit and used for amplifying voltage signals.
In this embodiment, since the defect is small, the converted voltage signal is extremely weak, and the weak signal needs to be amplified, and zero compensation is also required so that the amplified signal does not overrun. The invention directly adopts the AD620 direct current amplifying chip to amplify the direct current signal. The AD620 direct current amplifying chip is developed from a traditional three-operation amplifier (as shown in fig. 10), but some main performances are better than the design of an instrument amplifier formed by the three-operation amplifier, such as a wide power supply range (+ -2.3 to (+ -18V), the design volume is small, the power consumption is very low (the maximum power supply current is only 1.3 mA), and therefore, the AD620 direct current amplifying chip is suitable for low-voltage and low-power consumption application occasions. The monolithic structure of the AD620 DC amplifying chip and the laser crystal adjustment allow the circuit elements to be closely matched and tracked, thereby ensuring the inherent high performance of the circuit. The AD620 direct current amplifying chip is an instrument amplifier structure integrated by three operational amplifiers, simple differential bipolar input is provided for protecting the high precision of gain control, a triode at the input end of the AD620 direct current amplifying chip adopts a beta process to obtain lower input bias current, the collector current of the input triode is kept constant through feedback of the operational amplifier inside the input stage, and the input voltage is added to an external gain variable resistor RG.
Further, the method comprises the steps of: a voltage follower circuit;
the input end of the voltage follower circuit is connected to the output end of the direct current amplifying circuit, and the output end of the voltage follower circuit is connected to the input end of the recording analysis module and used for buffering and isolating the input voltage of the direct current amplifying circuit.
In this embodiment, as shown in fig. 11, the voltage follower circuit plays a role of buffering and isolation. The output impedance of a dc amplifier circuit is generally high, typically in the range of several kilohms to several tens of kilohms, and if the input impedance of the subsequent stage is relatively small, a significant portion of the signal is lost to the output resistance of the preceding stage. At this time, a voltage follower is required to buffer from it. Plays a role in supporting the upward and downward movement. Another advantage of using a voltage follower is that the input impedance is increased, so that the capacity of the input capacitor can be reduced substantially, providing a precondition for applying a high quality capacitor.
Further, the method comprises the steps of: roller type meter counter;
the output end of the roller type meter counting counter is connected to the input end of the recording analysis module and used for calculating the length of the material to be measured and sending the length to the recording analysis module and the amplified voltage signal to synchronously record.
In this embodiment, the recording analysis module is configured to record the detection result. The recording device can be purchased directly with a paper printing recorder, and can also convert analog signals into digital signals through an AD acquisition card and transmit the digital signals to computer software to form a recording analysis module, and the recording analysis module is acquired and stored by the computer software. The invention carries out data conversion through the developed AD acquisition card PCI-1710UL-DE, and then the computer software acquires and stores the signals. The stored voltage patterns are shown in fig. 12, and the amplified voltage waveforms can be recorded, and the corresponding meters can be recorded by using the voltage patterns, specifically, the broken lines in the figures are respectively 0.25V, 0.75V and 1.5V, the reference voltage is 5V, and the corresponding crack depths are 5%, 15% and 30%. The invention uses the roller type meter counter to obtain the corresponding meter data along with the rolling of the detection probe when detecting the flaw, and further uploads the meter data to the record analysis module.
Further, the method comprises the steps of: an audible and visual alarm module;
the input end of the audible and visual alarm module is connected to the detection probe and is used for automatically triggering audible and visual alarm when the fault detector breaks down.
In the embodiment, the audible and visual alarm is used for detecting whether the fault detector has faults, and when the fault detector has faults, the audible and visual alarm is automatically triggered to prompt an operator to stop the machine for maintenance. The design adopts an AD16-16SM electronic buzzer and a 12V high decibel loudspeaker loudspeaking alarm module. Because the detecting probe is a vulnerable part, whether the detecting probe is damaged is mainly monitored, a normal detecting probe has a signal output to the audible and visual alarm module, the damaged probe has no signal output, and when the audible and visual alarm module detects that the probe has no signal, audible and visual alarm is triggered by the relay switch.
The embodiment of the invention provides an eddy current flaw detection method capable of detecting conductor ultrafine wire cracks, which comprises the following steps:
s1, generating the resonance frequency signal through the resonance generator, and sending the resonance frequency signal to the material to be detected through the detection probe;
further, the generating the resonance frequency signal by the resonance generator before the sending the resonance frequency signal through the detection probe comprises:
and carrying out zero setting calibration on the voltage signal output by the signal conversion module through the zero point compensation circuit.
In this embodiment, the zero-setting calibration step can be referred to as the calibration step of the flaw detector by using a zero-point compensation circuit and a digital display direct-current voltmeter.
S2, the detection probe generates change according to the induced current of the material to be detected so as to generate resonance frequency change, and the resonance frequency signal is obtained;
s3, converting all resonant frequency signals into voltage signals through the signal conversion module;
further, the converting, by the signal conversion module, all the resonant frequency signals into the voltage signals and amplifying the voltage signals includes:
s301, performing frequency division processing on all the resonant frequency signals for 6 times through the frequency division circuit to obtain frequency division signals;
s302 converts the frequency-divided signal into the voltage signal by the frequency-voltage conversion circuit.
S4, correspondingly recording the voltage signal according to the length of the material to be tested through the recording analysis module;
further, the recording, by the recording analysis module, the voltage signal according to the length of the material to be measured includes:
s401, moving along with the detection probe through the roller type meter counter;
s402, synchronously transmitting the moving meter number to the record analysis module through the roller meter counter;
s403, synchronously transmitting the voltage signals to the record analysis module through the signal conversion module.
S5, analyzing and calculating the voltage signals through the recording and analyzing module to obtain crack depths of different positions of the material to be tested.
Further, the step of analyzing and calculating the voltage signal by the recording and analyzing module to obtain crack depths L of different positions of the material to be measured includes:
s501, acquiring the diameter D, full-range voltage U and amplified voltage signal Uo of the material to be measured;
s502 calculates the crack depth L by the diameter D, the full-range voltage U, and the amplified voltage signal Uo of the material to be measured, where the crack depth satisfies l=d×uo/U.
The detection results of the present invention will be further described in connection with analysis of test results.
The identification of the crack with the depth of 10um is not verified before the identification, so that metallographic analysis is needed for the flaw detection result, and whether the flaw detection result is correct or not is verified by the metallographic analysis result. The tungsten wire with the diameter of 0.1mm is selected for flaw detection and sampling for metallographic analysis, and as shown in fig. 13 and 14, the eddy current flaw detector can detect flaws with the depth of 10um, the upper part of fig. 13 and 14 are voltage maps detected by the flaw detector, and the lower part is a picture of metallographic examination.
It should be noted that: the metallographic examination mainly uses the quantitative metallographic principle and uses the measurement and calculation of the metallographic microstructure of a two-dimensional metallographic specimen grinding surface or film to determine the three-dimensional space morphology of an alloy structure, thereby establishing the quantitative relationship among alloy components, structures and performances. The design mainly analyzes the depth of the crack, so that the cross section of the sample is observed through a metallographic microscope, and the depth of the crack along the radial direction from the surface is measured for evaluation.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
It should be noted that in the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The use of the words first, second, third, etc. do not denote any order. These words may be interpreted as names.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms should not be understood as necessarily being directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
Claims (10)
1. An eddy current flaw detector for detecting cracks in a very fine wire of a conductor, comprising: the device comprises a resonance generator, a detection probe, a signal conversion module and a recording analysis module;
the output end of the resonance generator is connected to the transmitting end of the detection probe to form a 1-40MHz resonance frequency detection source, and the detection source generates induced current on the surface of the material to be detected when approaching the material to be detected;
the receiving end of the detection probe is connected to the input end of the signal conversion module and is used for receiving a resonant frequency signal returned by the material to be detected, and the detection probe changes according to the induced current of the material to be detected so as to generate resonant frequency change; the detection probe includes: flaw detection signal acquisition coil, interference signal compensation coil and comparator I1; the flaw detection signal acquisition coil is connected to the positive electrode of the comparator I1 and is used for transmitting and acquiring resonance frequency; the interference signal compensation coil is connected to the negative electrode of the comparator I1 and is used for generating a differential compensation signal so as to counteract external interference signals when receiving resonance frequency signals; the output end of the comparator I1 is connected to the input end of the signal conversion module;
the signal conversion module converts a resonance frequency signal generated by the detection probe into a voltage signal, and the signal conversion module comprises: a frequency dividing circuit and a frequency-voltage converting circuit; the input end of the frequency dividing circuit is connected to the receiving end of the detection probe and is used for dividing the frequency of the resonant frequency signal; the output end of the frequency dividing circuit is connected to the input end of the frequency-voltage conversion circuit and is used for converting the resonance frequency signal into a voltage signal; the output end of the signal conversion module is connected to the recording analysis module and is used for recording and analyzing the voltage signal in real time to realize flaw detection of the material to be detected.
2. An eddy current flaw detector for detecting cracks in a conductor microfilament as claimed in claim 1 comprising: zero compensation circuit and digital display DC voltmeter;
the zero compensation module is connected to the output end of the signal conversion module and used for adjusting the output voltage and the calibration reference voltage; the input end of the digital display direct current voltmeter is connected to the output end of the signal conversion module and used for displaying the current output voltage and matching with the zero compensation circuit to calibrate the reference voltage.
3. An eddy current flaw detector for detecting cracks in a conductor microfilament as claimed in claim 1 comprising: a DC amplifying circuit;
the output end of the zero compensation circuit is connected to the input end of the direct current amplifying circuit and used for amplifying voltage signals.
4. An eddy current flaw detector for detecting cracks in a conductor microfilament as claimed in claim 1 comprising: a voltage follower circuit;
the input end of the voltage follower circuit is connected to the output end of the direct current amplifying circuit, and the output end of the voltage follower circuit is connected to the input end of the recording analysis module and used for buffering and isolating the input voltage of the direct current amplifying circuit.
5. An eddy current flaw detector for detecting cracks in a conductor microfilament as claimed in claim 1 comprising: roller type meter counter;
the output end of the roller type meter counting counter is connected to the input end of the recording analysis module and used for calculating the length of the material to be measured and sending the length to the recording analysis module and the voltage signal to synchronously record.
6. An eddy current flaw detection method for detecting a crack in a very fine wire of a conductor, characterized in that it comprises, based on the eddy current flaw detector for detecting a crack in a very fine wire as defined in any one of claims 1 to 5:
generating the resonance frequency signal through the resonance generator and sending the resonance frequency signal to the material to be detected through the detection probe;
the detection probe generates a change according to the induced current of the material to be detected so as to generate a resonance frequency change, and the resonance frequency signal is obtained;
converting all the resonant frequency signals into the voltage signals by the signal conversion module;
correspondingly recording the voltage signal according to the length of the material to be measured through the recording analysis module;
and analyzing and calculating the voltage signal through the record analysis module to obtain crack depths of different positions of the material to be tested.
7. The method of eddy current flaw detection for detectable conductor microfilament flaws of claim 6 wherein said converting all of said resonant frequency signals to said voltage signals by said signal conversion module comprises:
performing frequency division processing on all the resonant frequency signals for 6 times through the frequency division circuit to obtain frequency division signals;
the frequency-divided signal is converted into the voltage signal by the frequency-voltage conversion circuit.
8. The method of eddy current flaw detection for detecting ultrafine wire flaws in conductors according to claim 6, wherein the recording of the voltage signal by the recording analysis module according to the length correspondence of the material to be tested comprises:
the roller type meter counter moves along with the detection probe;
synchronously transmitting the moving meter number to the record analysis module through the roller meter counter;
and synchronously transmitting the voltage signal to the record analysis module through the signal conversion module.
9. The eddy current flaw detection method for detecting ultrafine wire flaws of a conductor according to claim 6, wherein the analysis and calculation of the voltage signal by the recording and analyzing module to obtain flaw depths L at different positions of the material to be measured comprises:
acquiring the diameter D, full-range voltage U and amplified voltage signal Uo of the material to be measured;
and calculating the crack depth L according to the diameter D of the material to be detected, the full-range voltage U and the amplified voltage signal Uo, wherein the crack depth L=DxU0/U is satisfied.
10. The method of eddy current inspection for the detection of cracks in very fine wires of a conductor according to claim 6, wherein the generating of the resonant frequency signal by the resonant generator before the sending of the resonant frequency signal to the material under inspection by the inspection probe comprises:
and carrying out zero setting calibration on the voltage signal output by the signal conversion module through the zero point compensation circuit.
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| CN117571039A (en) * | 2024-01-11 | 2024-02-20 | 上海天沐自动化仪表有限公司 | Iron-inserting inductance sensor with output characteristic calibration |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117571039A (en) * | 2024-01-11 | 2024-02-20 | 上海天沐自动化仪表有限公司 | Iron-inserting inductance sensor with output characteristic calibration |
| CN117571039B (en) * | 2024-01-11 | 2024-04-02 | 上海天沐自动化仪表有限公司 | Iron-inserting inductance sensor with output characteristic calibration |
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