GB2617883A - An on-line monitoring system and a method of crack arresting via pulse current and crack state detecting using the same - Google Patents
An on-line monitoring system and a method of crack arresting via pulse current and crack state detecting using the same Download PDFInfo
- Publication number
- GB2617883A GB2617883A GB2216595.5A GB202216595A GB2617883A GB 2617883 A GB2617883 A GB 2617883A GB 202216595 A GB202216595 A GB 202216595A GB 2617883 A GB2617883 A GB 2617883A
- Authority
- GB
- United Kingdom
- Prior art keywords
- crack
- signal
- wired
- computer system
- impedance
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000012544 monitoring process Methods 0.000 title claims abstract description 27
- 238000000034 method Methods 0.000 title claims description 23
- 238000001514 detection method Methods 0.000 claims abstract description 89
- 239000002184 metal Substances 0.000 claims abstract description 69
- 230000008859 change Effects 0.000 claims abstract description 14
- 238000002847 impedance measurement Methods 0.000 claims description 46
- 239000003990 capacitor Substances 0.000 claims description 45
- 230000005284 excitation Effects 0.000 claims description 42
- 230000003321 amplification Effects 0.000 claims description 40
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 40
- 239000000523 sample Substances 0.000 claims description 32
- 230000007423 decrease Effects 0.000 claims description 14
- 230000005291 magnetic effect Effects 0.000 claims description 14
- 230000005292 diamagnetic effect Effects 0.000 claims description 6
- 238000007599 discharging Methods 0.000 claims description 3
- 238000002844 melting Methods 0.000 claims description 3
- 230000008018 melting Effects 0.000 claims description 3
- 230000004044 response Effects 0.000 claims description 3
- 238000005516 engineering process Methods 0.000 description 12
- 230000000694 effects Effects 0.000 description 11
- 238000010586 diagram Methods 0.000 description 8
- 230000008569 process Effects 0.000 description 7
- 238000013016 damping Methods 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 238000004146 energy storage Methods 0.000 description 3
- 238000009659 non-destructive testing Methods 0.000 description 3
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000012937 correction Methods 0.000 description 2
- 230000001939 inductive effect Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000010355 oscillation Effects 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 101150052370 fol1 gene Proteins 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
- G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws
- G01N27/90—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P6/00—Restoring or reconditioning objects
- B23P6/04—Repairing fractures or cracked metal parts or products, e.g. castings
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
Abstract
A system for real time monitoring of crack arresting via pulse current using an eddy current flaw detection module which comprises a lower computer system, a pulse current generation module and an eddy current flaw detection module. Crack arresting via pulse current is monitored using the system by using the pulse current generation module to output a pulse current to arrest the crack; the eddy current flaw detection module monitors the impedance change information in real time; the host computer system monitors the crack state of the metal workpiece according to the impedance results.
Description
An On-line Monitoring System and a Method of Crack Arresting via Pulse Current and Crack State Detecting Using the Same
Field of Invention
The present invention relates to the field of crack treatment and detection technology, and relates in particular to an on-line monitoring system and a method of crack arresting via pulse current and crack state detecting using the system.
Background Art
Due to the existence of cracks on a metal workpiece, the pulse current will generate a high Joule heat at the crack tip when the pulse current is input to the metal workpiece, causing the crack tip to melt instantly, thereby preventing the crack from continuing to expand. in order to achieve the purpose of the crack arrest via the pulse current, it is necessary to inject a suitable pulse current. It will be difficult to achieve the expected crack arrest effect if the selected pulse current parameters are unreasonable. At present, offline technology is a commonly used crack state detection technology in engineering. That is, the metal workpiece is processed first, and then the metal flaw detection technology is used to detect the internal crack state of the processed metal workpiece. It needs to be processed again if the processing effect is unsatisfactory, so that the whole process is complicated, and the waste of resources cannot be ignored. Therefore, if there is a system that can monitor the crack state in real time while performing the crack arrest by the pulse current on the metal workpiece, the efficiency and effect of the crack arrest by the pulse current can be greatly improved.
In order to improve the efficiency and effect of the crack arrest via the pulse current, the present invention discloses an on-line monitoring system and a method of crack arresting via pulse current and crack state detecting using the system. That is, the crack state of the metal workpiece is monitored in real time by using the eddy current non-destructive testing technology while the pulse current is used to arrest the crack. In this way, the state information of the crack can be obtained in real time while the pulse current is arresting the crack, thereby improving the efficiency and effect of the crack arrest via the pulse current.
Summary of the Invention
In order to improve the efficiency and effect of the crack arrest via the pulse current, the present invention discloses an on-line monitoring system and a method of crack arresting via pulse current and crack state detecting using the system. That is, the eddy current non-destructive testing technology is used to monitor the crack state of the metal workpiece in real time while the pulse current is used for the crack arrest. In this way, the state of the crack can be monitored in real time while the pulse current is arresting the crack, thereby improving the efficiency and effect of the crack arrest.
An on-line monitoring system comprises a host computer system, a lower computer system, a pulse current generation module and an eddy current flaw detection module; the lower computer system comprises a single-chip microcomputer and an impedance measurement chip; the pulse current generation module comprises a charging switch, a discharge switch, a rectifier circuit, a power supply and a capacitor bank; the eddy current flaw detection module comprises a signal amplification circuit, a voltage-controlled current source, a detection probe, a relay and an amplification circuit; the detection probe comprises a coil frame, a plastic insulating shell, an excitation coil, a toroidal core and a detection coil; the host computer system is wired with the single-chip microcomputer and the impedance measurement chip; the single-chip microcomputer is wired with the impedance measurement chip; the single-chip microcomputer is wired with the charging switch and the discharge switch; the impedance measurement chip is wired with the signal amplification circuit; the power supply is wired with the rectifier circuit; the rectifier circuit is wired with the charging switch; the charging switch is wired with the capacitor bank; the capacitor bank is wired with the power supply; the capacitor bank is wired with the discharge switch; the signal amplification circuit is wired with the voltage-controlled current source; the voltage-controlled current source is wired with the excitation coil in the detection probe; the detection coil in the detection probe is wired with the relay; the relay is wired with the amplifier circuit; the amplifier circuit is wired with the impedance measurement chip.
Further, the power supply is a 110V or a 220V AC power supply.
Further, the impedance measurement chip integrates a digital frequency generator, an analog-to-digital converter and a DSP engine, the digital frequency generator generates a sinusoidal voltage signal of a specific frequency for excitation of the detection probe, a response signal obtained CM the detection probe is sampled by the analog-to-digital converter, and the DSP engine performs discrete Fourier transform to obtain the impedance value to be measured.
Further, the excitation coil is wound on the toroidal core, the detection coil is wound on the coil frame and placed inside the toroidal core, and the plastic insulating shell is installed on the outer layer of the excitation coil to protect the detection probe from external current.
The invention discloses a method of crack arresting via pulse current and crack state detecting using the on-line monitoring system comprises the following steps: step (1): installing the detection probe on one side of the metal workpiece to be processed; connecting the signal connection between the host computer system and the single-chip microcomputer; connecting the signal connection between the host computer system and the impedance measurement chip; connecting the signal connection between the single-chip microcomputer and the impedance measurement chip; connecting the signal connection among the single-chip microcomputer, the charging switch and the discharging switch; connecting the signal connection between the impedance measurement chip and the signal amplification circuit; wiring the power supply with the rectifier circuit; wiring the rectifier circuit with the charging switch; wiring the charging switch with the capacitor bank; wiring the capacitor bank with the power supply; wiring the capacitor bank with the discharge switch; wiring the discharge switch with the metal workpiece; wiring the capacitor bank with the metal workpiece; connecting the signal connection between the impedance measurement chip and the signal amplification circuit; connecting the signal connection between the signal amplification circuit and the voltage-controlled current source; wiring the voltage-controlled current with the excitation coil in the detection probe; connecting the signal connection between the detection coil in the detection probe and the relay; connecting the signal connection between the relay and the amplification circuit; connecting the signal connection between the amplification circuit and the impedance measurement chip; turning on the power source of the host computer system and the voltage-controlled current source; turning on the start switch of the power supply; step (2): sending a working signal to the lower computer system via the host computer system, then controlling the charging switch to close and the discharge switch to open via the single-chip microcomputer, charging the capacitor bank via the power supply; controlling the discharge switch to close and the charging switch to open via the single-chip microcomputer at full charge capacity of the capacitor bank, generating a pulse current with high energy density and inputting it into the metal workpiece via the capacitor bank; generating a high Joule heat at the crack tip via the pulse current, thereby melting the crack tip instantaneously, preventing the crack from continuing to expand; step (3): transmitting, simultaneous to crack arresting, a control command generated by the host computer system to the impedance measurement chip via the single-chip microcomputer. outputting a sinusoidal voltage signal of the set frequency to the signal amplification circuit via the impedance measurement chip, and amplifying the sinusoidal voltage signal via the signal amplification circuit; generating an alternating current signal that can directly drive the excitation coil via the voltage-controlled current source; inputting the alternating current signal into the excitation coil via the voltage-controlled current source, and generating an alternating excitation magnetic field in the measured space via the excitation coil; generating an eddy current inside the metal workpiece via the excitation magnetic field, at the same time, producing a diamagnetic field with the same frequency as the excitation magnetic field via the eddy current; the crack affecting the flow of the eddy current inside the metal workpiece, thereby changing the strength of the diamagnetic field and the excitation magnetic field, in turn, causing the change of the impedance in the detection coil; step (4): isolating and transmitting the impedance change information to the amplification circuit via the relay; then inputting the amplified signal to the impedance measurement chip via the amplification circuit; performing demodulation operation on the detected signal via the impedance measurement chip, and transmitting the impedance results to the host computer system via the single-chip microcomputer; step (5). judging the crack changes of the metal workpiece according to the change of the impedance via the host computer system, the sharp ends of the crack are gradually passivated after the functions of the pulse current, and the impedance results obtained in the host computer system gradually decrease; stopping the input of the pulse current when the impedance result decreases to the critical value, indicating that the crack on the metal Further, the detection coil and the metal workpiece can be simplified as a transformer model in the process of the eddy current flaw detection, the detection coil can be regarded as a primary coil, and the metal workpiece can be regarded as a secondary coil. where k and I, are the equivalent resistance and equivalent inductance in the detection coil, 1-?". and 1." are the equivalent resistance and equivalent inductance in the metal workpiece, (fey is the excitation voltage, and M is the mutual inductance between the detection coil and the metal workpiece; when the alternating current is applied to the detection coil, according to the Kirchhoff's Law: RdI + joLdI -7 (DAS H. =1-I, IV? + -joik/ d =0 solving the system of equations can obtain that: CO2M2 02M 2 R, + +.jco(L, c Lu) SAP al AI' Z -LI = R, ++ ja)(L 1,") 1 + co2,, 1,2 + ro2 among them, Z, is the impedance value of the primary coil; therefore, the equivalent resistance R, and the equivalent inductive reactance X, of the detection coil can be obtained: (02Al2 (2,1j2 d 2 2+ 2 Lit, L" it can be seen that the impedance of the detection coil is affected by R,, L and M, that is, the impedance of the detection coil is affected by the crack state of the metal workpiece; when the crack tip in the metal workpiece is passivated by the pulse current, the equivalent resistance R of the metal workpiece decreases, and the equivalent resistance R, of the detection coil decreases, which results in a decrease in the impedance value Z of the detection coil; therefore, the eddy current generated in the tested metal workpiece under the action of the alternating magnetic field can cause the impedance of the detection coil to change, and the crack arrest effect of the pulse current can be determined by observing the impedance change value in the host computer.
Further, the capacitor energy storage and discharge circuit can be explained by the equivalent circuit diagram in the process of the crack arrest via the pulse current; where S is the discharge closing switch, C is the ideal capacitor, U f is the voltage value after the capacitor is fully charged, R is the total resistance of the discharge circuit, and L is the total inductance of the discharge circuit; according to the Kirchhoff Current Law (KCL), the Kirchhoff Voltage Law (K11,) and the Volt Ampere Characteristics (VAR) of each circuit element, the following circuit equations can be obtained: di 1 r Ri + L-+-/di =CI di C differentiating the above formula for time t can get: d2i LC-+RC-di i =0 6112 di the initial conditions in this circuit are: t =0, 1=0, and the voltage of the R C: capacitor is (If; when the damping coefficient C = (under the 2 L condition of under-damping), the discharge circuit will generate a pulse current with oscillation attenuation, and its value is: U.C C2 i) Aine. i(0=
L
the peak value and the arrival time ax of the first current of the pulse current are: -ct IfinaLI = f e473 x j L C iiim --11-X7 arctan
C
the period of the pulse current is: T= 2;z-
_ R
LC 41:2 according to the above formulas, it can be seen that the characteristic parameters of the pulse current are affected by the parameters of the discharge circuit, that is, the total capacity of the capacitor C, the charging voltage U1, the total resistance of the discharge circuit R and the total inductance of the discharge circuit L, the parameters of the discharge circuit can be adjusted according to the above fomntlas in the process of the crack arrest via the pulse current, so as to obtain suitable parameter values of the pulse current characteristics.
Further, the crack in the metal workpiece has a critical crack length 1, ; when the crack length 1, on the metal workpiece is smaller than /, , it means that the crack does not affect the normal use of the metal workpiece; if 4, it means that the crack will exhibit unstable crack propagation when it is subjected to external force, which will affect the actual performance and the life of the metal workpiece; and the critical crack length Ic is expressed as follows: = 1 (0-ma, -0-1 where 47 is the fatigue fracture toughness of the metal workpiece material, affax is the maximum first main stress at the crack, o-, is the minimum first main stress at the crack, f is the correction factor (take 1-1.12); the impedance results obtained in the host computer system gradually decrease when the crack tip is gradually passivated, and it indicates that the crack on the metal workpiece is effectively arrested when the impedance value is less than the critical impedance value corresponding to the critical crack length k.
The beneficial effects of the present invention are as follows: 1, The on-line monitoring system and a method of crack arresting via pulse current and crack state detecting using the system proposed by the present invention has the advantages of strong reliability and high practical value, and is beneficial to promoting the popularization and application of the crack-arrest technology and the eddy current flaw detection technology.
2, The on-line monitoring system and a method of crack arresting via pulse current and crack state detecting using the system proposed by the present invention uses the pulse current to arrest the crack on the metal workpiece, and uses the eddy current flaw detection to monitor the changes of the crack state of the metal workpiece in real time, thereby greatly improving the work efficiency.
3, The on-line monitoring system and a method of crack arresting via pulse current and crack state detecting using the system proposed by the present invention can not only monitor the changes of the crack state in real time during the use of the metal workpiece, but also start from the beginning of the use of the metal workpiece to give an early warning of the bad state of the equipment.
Brief Description of the Drawings
Fig. 1 is a schematic diagram of the module connection of the on-line monitoring system of the present invention.
Fig. 2 is a schematic diagram of the device connection of the on-line monitoring system of the present invention.
Fig. 3 is a schematic diagram of the pulse current generation module of the on-line monitoring system of the present invention.
Fig. 4 is a schematic diagram of the eddy current flaw detection module of the on-line monitoring system of the present invention.
Fig. 5 is a sectional view of the detection probe of the on-line monitoring system of the present invention.
Fig. 6 is a flow chat of the method of crack arresting via pulse current and crack state detecting using the on-line monitoring system of the present invention.
Fig. 7 is a transformer model diagram of the method of crack arresting via pulse current and crack state detecting using the on-line monitoring system of the present invention.
Fig. 8 is an equivalent circuit diagram of the capacitor energy storage and discharge circuit of the method of crack arresting via pulse current and crack state detecting using the on-line monitoring system of the present invention.
The reference numerals of the present invention are described in detail as follows: 1 is the upper computer system; 2 is the lower computer system, 21 is the single-chip microcomputer, 22 is the impedance measurement chip; 3 is the pulse current generation module, 31 is the charging switch, 32 is the discharge switch, 33 is the rectifier circuit, 34 is the power supply, and 35 is the capacitor bank; 4 is the eddy current flaw detection module, 41 is the signal amplification circuit, 42 is the voltage-controlled current source, 43 is the detection probe, 44 is the relay, 45 is the amplifier circuit: 431 is the coil frame, 432 is the plastic insulating shell, 433 is the excitation coil, 434 is the toroidal core, 435 is the detection coil; 5 is the metal workpiece; 6 is the crack.
Embodiments The present invention will be further described with reference to the accompanying drawings: As shown in Fig.1 the on-line monitoring system comprises a host computer system 1, a lower computer system 2, a pulse current generation module 3 and an eddy current flaw detection module 4; as shown in Fig), the lower computer system 2 comprises a single-chip microcomputer 21 and an impedance measurement chip 22; as shown in Fiu.3, the pulse current generation module 3 comprises a charging switch 31, a discharge switch 32, a rectifier circuit 33, a power supply 34 and a capacitor bank 35; as shown in Fig4, the eddy current flaw detection module 4 comprises a signal amplification circuit 41, a voltage-controlled current source 42, a detection probe 43, a relay 44, and an amplification circuit 45; as shown in Fig.5, the detection probe 43 comprises a coil frame 431, a plastic insulating shell 432, an excitation coil 433, a toroidal core 434 and a detection coil 435; as shown in Fig.2, the host computer system 1 is wired with the single-chip microcomputer 21 and the impedance measurement chip 22; the single-chip microcomputer 21 is wired with the impedance measurement chip 22; the single-chip microcomputer 21 is wired with the charging switch 31 and the discharge switch 32; the impedance measurement chip 22 is wired with the signal amplification circuit 41; the power supply 34 is wired with the rectifier circuit 33; the rectifier circuit 33 is wired with the charging switch 31; the charging switch 31 is wired with the capacitor bank 35; the capacitor bank 35 is wired with the power supply 34; the capacitor bank 35 is wired with the discharge switch 32; the signal amplification circuit 41 is wired with the voltage-controlled current source 42; the voltage-controlled current source 42 is wired with the excitation coil 433 in the detection probe 43; the detection coil 435 in the detection probe 43 is wired with the relay 44; the relay 44 is wired with the amplifier circuit 45; the amplifier circuit 45 is wired with the impedance measurement chip 22.
Further, the power supply 34 is a 110V or a 220V AC power supply.
Further, the impedance measurement chip 22 integrates a digital frequency generator, an analog-to-digital converter and a DSP engine, the digital frequency generator generates a sinusoidal voltage signal of a specific frequency for excitation of the detection probe 43, a response signal obtained on the detection probe 43 is sampled by the analog-to-digital converter, and the DSP performs discrete Fourier transform to obtain the impedance value to be measured.
Further, as shown in Fig.5, the excitation coil 433 is wound on the toroidal core 434, the detection coil 435 is wound on the coil frame 431 and placed inside the toroidal core 434, and the plastic insulating shell 432 is installed on the outer layer of the excitation coil 433 to protect the detection probe 43 from external current.
As shown in Fig.6, the invention discloses a method of crack arresting via pulse current and crack state detecting using the on-line monitoring system comprises the following steps: step (1): installing the detection probe 43 on one side of the metal workpiece 5 to be processed; connecting the signal connection between the host computer system 1 and the single-chip microcomputer 21; connecting the signal connection between the host computer system 1 and the impedance measurement chip 22; connecting the signal connection between the single-chip microcomputer 21 and the impedance measurement chip 22; connecting the signal connection among the single-chip microcomputer 21, the charging switch 31 and the discharging switch 32; connecting the signal connection between the impedance measurement chip 22 and the signal amplification circuit 41; wiring the power supply 34 with the rectifier circuit 33; wiring the rectifier circuit 33 with the charging switch 31; wiring the charging switch 31 with the capacitor bank 35; wiring the capacitor bank 35 with the power supply 34; wiring the capacitor bank 35 with the discharge switch 32; wiring the discharge switch 32 with the metal workpiece 5; wiring the capacitor bank 35 with the metal workpiece 5. connecting the signal connection between the impedance measurement chip 22 and the signal amplification circuit 41; connecting the signal connection between the signal amplification circuit 41 and the voltage-controlled current source 42; wiring the voltage-controlled current 43 with the excitation coil 433 in the detection probe 43; connecting the signal connection between the detection coil 435 in the detection probe 43 and the relay 44; connecting the signal connection between the relay 44 and the amplification circuit 45; connecting the signal connection between the amplification circuit 45 and the impedance measurement chip 22; turning on the power source of the host computer system 1 and the voltage-controlled current source 42; turning on the start switch of the power supply 34; step (2): sending a working signal to the lower computer system 2 via the host computer system 1, then controlling the charging switch 31 to close and the discharge switch 32 to open via the single-chip microcomputer 21, charging the capacitor bank 35 via the power supply 34; controlling the discharge switch 32 to close and the charging switch 31 to open via the single-chip microcomputer 21 at full charge capacity of the capacitor bank 35, generating a pulse current with high energy density and inputting it into the metal workpiece 5 via the capacitor bank 35; generating a high Joule heat at the crack 6 tip via the pulse current, thereby melting the crack 6 tip instantaneously, preventing the crack 6 from continuing to expand; step (3) transmitting, simultaneous to crack arresting, a control command generated by the host computer system 1 to the impedance measurement chip 22 via the single-chip microcomputer 21; outputting a sinusoidal voltage signal of the set frequency to the signal amplification circuit 41 via the impedance measurement chip 22, and amplifying the sinusoidal voltage signal via the signal amplification circuit 41; generating an alternating current signal that can directly drive the excitation coil 433 via the voltage-controlled current source 42; inputting the alternating current signal into the excitation coil 433 via the voltage-controlled current source 42, and generating an alternating excitation magnetic field in the measured space via the excitation coil 433; generating an eddy current inside the metal workpiece 5 via the excitation magnetic field, at the same time, producing a diamagnetic field with the same frequency as the excitation magnetic field via the eddy current; the crack 6 affecting the flow of the eddy current inside the metal workpiece 5, thereby changing the strength of the diamagnetic field and the excitation magnetic field, in turn, causing the change of the impedance in the detection coil 435; step (4): isolating and transmitting the impedance change information to the amplification circuit 45 via the relay 44; then inputting the amplified signal to the impedance measurement chip 22 via the amplification circuit 45; performing demodulation operation on the detected signal via the impedance measurement chip 22, and transmitting the impedance results to the host computer system 1 via the single-chip microcomputer 21; step (5): judging the crack 6 changes of the metal workpiece 5 according to the change of the impedance via the host computer system 1, the sharp ends of the crack 6 are gradually passivated after the functions of the pulse current, and the impedance results obtained in the host computer system 1 gradually decrease; stopping the input of the pulse current when the impedance result decreases to the critical value, indicating that the crack 6 on the metal workpiece 5 is effectively arrested.
The principle of the present invention is as follows: when a pulse current is input to a metal workpiece containing cracks, the contact interface is formed at the crack, resulting in a large impedance. Under the action of the pulse current, a high joule heat will be generated, which makes the crack tip melt instantaneously and produces metallurgical bonding, the further propagation of the crack is prevented and the impedance is reduced. In order to select reasonable pulse current parameters and achieve the expected crack arrest effect, the offline technology currently used in the project is not only cumbersome to detect the internal crack state of the processed metal workpiece, but also easily wastes resources. Therefore, the present invention proposes an on-line monitoring system and a method of crack arresting via pulse current and crack state detecting using the system according to the above phenomenon, that is, the eddy current nondestructive testing technology is used to monitor the crack state of the metal workpiece in real time while the pulse current is used for the crack arrest. In this way, the state of the crack can be monitored in real time while the pulse current is arresting the crack, thereby improving the efficiency and effect of the crack arrest, promoting the popularization and application of the crack-arrest technology and the eddy current flaw detection technology.
Further, as shown in Fig.7, the detection coil 435 and the metal workpiece 5 can be simplified as a transformer model in the process of the eddy current flaw detection, the detection coil 435 can be regarded as a primary coil, and the metal workpiece 5 can be regarded as a secondary coil; where Rd and L are the equivalent resistance and equivalent inductance in the detection coil 435, R and L, are the equivalent resistance and equivalent inductance in the metal workpiece 5, U" is the excitation voltage, and A4 is the mutual inductance between the detection coil 435 and the metal workpiece 5; when the alternating current is applied to the detection coil 435, according to the Kirchhoffs Law: + jo41 -1691141 = + fol1," -,/(011, = 0 solving the system of equations can obtain that: LIG" dM c +o2m2 R,2, + I It+ c o ce; c°2A/12 R + fro(L + d + aE Ic I" among them, Z, is the impedance value of the primary coil; therefore, the equivalent resistance R., and the equivalent inductive reactance X" of the detection coil 435 can be obtained: co2A/1 R R,7+ coW (02A/12 d 12 ± ( 02 1,2 it can be seen that the impedance of the detection coil 435 is affected by R L " and M, that is, the impedance of the detection coil 435 is affected by the crack 6 state of the metal workpiece 5; when the crack 6 tip in the metal workpiece 5 is passivated by the pulse current, the equivalent resistance I?", of the metal workpiece 5 decreases, and the equivalent resistance R of the detection coil 435 decreases, which results in a decrease in the impedance value Z, of the detection coil 435; therefore, the eddy current generated in the tested metal workpiece 5 under the action of the alternating magnetic field can cause the impedance of the detection coil 435 to change, and the crack arrest effect of the pulse current can be determined by observing the impedance change value in the host computer 1.
Further, as shown in Fig.8, the capacitor energy storage and discharge circuit can be explained by the equivalent circuit diagram in the process of the crack arrest via the pulse current; where S is the discharge closing switch, C is the ideal capacitor, (I is the voltage value after the capacitor is fully charged, R is the total resistance of the discharge circuit, and L is the total inductance of the discharge circuit; according to the Kirchhoff Current Law (KCL), the Kirchhoff Voltage Law (Ki7L) and the Volt Ampere Characteristics ( R) of each circuit element, the following circuit equations can be obtained: di 1 Ri + + idt =
C
differentiating the above formula for time t can get: LC-RC+i = 0 dt2 dt the initial conditions in this circuit are: t =0, i =0, and the voltage of the
R
capacitor is U _ f; when the damping coefficient T<1 (under the condition of under-damping), the discharge circuit will generate a pulse current with oscillation attenuation, and its value is: i(t) - U1 c
C S
j1_c2 L the peak value I., and the arrival time t." of the first current of the pulse current are: c amtan = f,Ite:177
-C
tlnax arc an the period of the pulse current is:
T -
1 R2 LC 41! according to the above formulas, it can be seen that the characteristic parameters of the pulse current are affected by the parameters of the discharge circuit, that is, the total capacity of the capacitor C, the charging voltage U1 the total resistance of the discharge circuit R and the total inductance of the discharge circuit L, the parameters of the discharge circuit can be adjusted according to the above formulas in the process of the crack arrest via the pulse current, so as to obtain suitable parameter values of the pulse current characteristics.
Further, the crack 6 in the metal workpiece 5 has a critical crack length when the crack 6 length 1" on the metal workpiece 5 is smaller than I, it means that the crack 6 does not affect the normal use of the metal workpiece 5; if 1,1" it means that the crack 6 will exhibit unstable crack propagation when it is subjected to external force, which will affect the actual performance and the life of the metal workpiece 5; and the critical crack length lc is expressed as follows: where K". is the fatigue fracture toughness of the metal workpiece 5 material, is the maximum first main stress at the crack 6, o is the minimum first main stress at the crack 6, f is the correction factor (take 1-1.12); the impedance results obtained in the host computer system 1 gradually decrease when the crack 6 tip is gradually passivated, and it indicates that the crack 6 on the metal workpiece 5 is effectively arrested when the impedance value is less than the critical impedance value corresponding to the critical crack length I. Description of the embodiments of the present specification is merely an enumeration of the implementation fonns of the inventive concept of the present invention, which shall not be construed as limiting the scope of the present invention to the specific forms expressed in the embodiments. Equivalent technical solutions that a skilled person of the art may construct from the conception of the present invention shall fall under the scope of the present invention.
Claims (5)
- Claims 1 An on-line monitoring system, comprising a host computer system, a lower computer system, a pulse current generation module and an eddy current flaw detection module; the lower computer system comprises a single-chip microcomputer and an impedance measurement chip; the pulse current generation module comprises a charging switch, a discharge switch, a rectifier circuit, a power supply and a capacitor bank; the eddy current flaw detection module comprises a signal amplification circuit, a voltage-controlled current source, a detection probe, a relay and an amplification circuit; the detection probe comprises a coil frame, a plastic insulating shell, an excitation coil, a toroidal core and a detection coil; characterized in that: the host computer system is wired with the single-chip microcomputer and the impedance measurement chip; the single-chip microcomputer is wired with the impedance measurement chip; the single-chip microcomputer is wired with the charging switch and the discharge switch; the impedance measurement chip is wired with the signal amplification circuit; the power supply is wired with the rectifier circuit; the rectifier circuit is wired with the charging switch; the charging switch is wired with the capacitor bank; the capacitor bank is wired with the power supply; the capacitor bank is wired with the discharge switch; the signal amplification circuit is wired with the voltage-controlled current source; the voltage-controlled current source is wired with the excitation coil in the detection probe; the detection coil in the detection probe is wired with the relay the relay is wired with the amplifier circuit; the amplifier circuit is wired with the impedance measurement chip.
- 2 The on-line monitoring system according to claim 1, characterized in that the power supply is a 110V or a 220V AC power supply
- 3 The on-line monitoring system according to claim 1, characterized in that the impedance measurement chip integrates a digital frequency generator, an analog-to-digital converter and a DSP engine, the digital frequency generator generates a sinusoidal voltage signal of a specific frequency for excitation of the detection probe, a response signal obtained on the detection probe is sampled by the analog-to-digital converter, and the DSP engine performs discrete Fourier transform to obtain the impedance value to be measured.
- 4 The on-line monitoring system according to claim 1, characterized in that the excitation coil is wound on the toroidal core, the detection coil is wound on the coil frame and placed inside the toroidal core, and the plastic insulating shell is installed on the outer layer of the excitation coil to protect the detection probe from external current.
- 5. A method of crack arresting via pulse current and crack state detecting using the on-line monitoring system of claim 1, characterized in that the method comprises the following steps: step (1): installing the detection probe on one side of the metal workpiece to be processed; connecting the signal connection between the host computer system and the single-chip microcomputer; connecting the signal connection between the host computer system and the impedance measurement chip; connecting the signal connection between the single-chip microcomputer and the impedance measurement chip; connecting the signal connection among the single-chip microcomputer, the charging switch and the discharging switch; connecting the signal connection between the impedance measurement chip and the signal amplification circuit; wiring the power supply with the rectifier circuit; wiring the rectifier circuit with the charging switch; wiring the charging switch with the capacitor bank; wiring the capacitor bank with the power supply; wiring the capacitor bank with the discharge switch; wiring the discharge switch with the metal workpiece; wiring the capacitor bank with the metal workpiece; connecting the signal connection between the impedance measurement chip and the signal amplification circuit; connecting the signal connection between the signal amplification circuit and the voltage-controlled current source; wiring the voltage-controlled current with the excitation coil in the detection probe; connecting the signal connection between the detection coil in the detection probe and the relay; connecting the signal connection between the relay and the amplification circuit; connecting the signal connection between the amplification circuit and the impedance measurement chip; turning on the power source of the host computer system and the voltage-controlled current source; turning on the start switch of the power supply; step (2): sending a working signal to the lower computer system via the host computer system, then controlling the charging switch to close and the discharge switch to open via the single-chip microcomputer, charging the capacitor bank via the power supply; controlling the discharge switch to close and the charging switch to open via the single-chip microcomputer at full charge capacity of the capacitor bank, generating a pulse current with high energy density and inputting it into the metal workpiece via the capacitor bank; generating a high Joule heat at the crack tip via the pulse current, thereby melting the crack tip instantaneously, preventing the crack from continuing to expand; step (3) transmitting, simultaneous to crack arresting, a control command generated by the host computer system to the impedance measurement chip via the single-chip microcomputer; outputting a sinusoidal voltage signal of the set frequency to the signal amplification circuit via the impedance measurement chip, and amplifying the sinusoidal voltage signal via the signal amplification circuit; generating an alternating current signal that can directly drive the excitation coil via the voltage-controlled current source; inputting the alternating current signal into the excitation coil via the voltage-controlled current source, and generating an alternating excitation magnetic field in the measured space via the excitation coil; generating an eddy current inside the metal workpiece via the excitation magnetic field, at the same time, producing a diamagnetic field with the same frequency as the excitation magnetic field via the eddy current; the crack affecting the flow of the eddy current inside the metal workpiece, thereby changing the strength of the diamagnetic field and the excitation magnetic field, in turn, causing the change of the impedance in the detection coil; step (4): isolating and transmitting the impedance change information to the amplification circuit via the relay; then inputting the amplified signal to the impedance measurement chip via the amplification circuit; performing demodulation operation on the detected signal via the impedance measurement chip, and transmitting the impedance results to the host computer system via the single-chip microcomputer; step (5): judging the crack changes of the metal workpiece according to the change of the impedance via the host computer system, the sharp ends of the crack are gradually passivated after the functions of the pulse current, and the impedance results obtained in the host computer system gradually decrease; stopping the input of the pulse current when the impedance result decreases to the critical value, indicating that the crack on the metal workpiece is effectively arrested.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB2216595.5A GB2617883B (en) | 2022-11-08 | 2022-11-08 | An on-line monitoring system and a method of crack arresting via pulse current and crack state detecting using the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB2216595.5A GB2617883B (en) | 2022-11-08 | 2022-11-08 | An on-line monitoring system and a method of crack arresting via pulse current and crack state detecting using the same |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB202216595D0 GB202216595D0 (en) | 2022-12-21 |
| GB2617883A true GB2617883A (en) | 2023-10-25 |
| GB2617883B GB2617883B (en) | 2024-11-27 |
Family
ID=84839826
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB2216595.5A Active GB2617883B (en) | 2022-11-08 | 2022-11-08 | An on-line monitoring system and a method of crack arresting via pulse current and crack state detecting using the same |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2617883B (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7211767B1 (en) * | 2004-12-27 | 2007-05-01 | Emc Corporation | Techniques for treating a surface crack on a component |
| CN107900507A (en) * | 2017-11-14 | 2018-04-13 | 哈尔滨工业大学 | Pulse current repair device and method for microcracks in metal pipe fittings |
| CN107931948A (en) * | 2017-11-14 | 2018-04-20 | 哈尔滨工业大学 | Device and method for repairing microcracks in non-ferromagnetic metal pipe fittings |
| CN113547281A (en) * | 2021-07-06 | 2021-10-26 | 山西太钢不锈钢股份有限公司 | Method for repairing surface cracks of leveling roller and performing nondestructive testing |
-
2022
- 2022-11-08 GB GB2216595.5A patent/GB2617883B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7211767B1 (en) * | 2004-12-27 | 2007-05-01 | Emc Corporation | Techniques for treating a surface crack on a component |
| CN107900507A (en) * | 2017-11-14 | 2018-04-13 | 哈尔滨工业大学 | Pulse current repair device and method for microcracks in metal pipe fittings |
| CN107931948A (en) * | 2017-11-14 | 2018-04-20 | 哈尔滨工业大学 | Device and method for repairing microcracks in non-ferromagnetic metal pipe fittings |
| CN113547281A (en) * | 2021-07-06 | 2021-10-26 | 山西太钢不锈钢股份有限公司 | Method for repairing surface cracks of leveling roller and performing nondestructive testing |
Also Published As
| Publication number | Publication date |
|---|---|
| GB202216595D0 (en) | 2022-12-21 |
| GB2617883B (en) | 2024-11-27 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN100575967C (en) | Device and method for real-time measurement of dynamic resistance of AC spot welding | |
| CN110146777A (en) | A generator/converter rotor turn-to-turn short circuit fault detection method | |
| CN201681133U (en) | Dry-type reactor interturn insulation detection device | |
| CN110954763B (en) | A non-destructive islanding detection method for microgrid based on harmonic current injection and harmonic impedance measurement | |
| CN108318791B (en) | Insulation Fault Discrimination Method for Inter-turn Insulation of Air-core Reactor Based on Frequency-Domain Characteristic Analysis | |
| WO2011000134A1 (en) | Method for detecting transformer winding state utilizing vibration waveform | |
| CN104156017B (en) | High-power high-frequency transformer bilayer oil temperature monitoring system and method | |
| CN110376454B (en) | Research platform for relevance of radial deformation of winding and oscillatory wave and test method thereof | |
| CN107315198A (en) | induction cooker and cooker detection method | |
| Yi et al. | Expulsion analysis of resistance spot welding on zinc-coated steel by detection of structure-borne acoustic emission signals | |
| CN100525982C (en) | Quality control device and method for resistance spot welding | |
| CN105675933A (en) | Ignition circuit of controllable discharge sphere gap in reactor inter-turn insulation detector | |
| CN107271866B (en) | Test device and method for direct effect of quadruple continuous time sequence lightning stroke | |
| CN106646157A (en) | Series arc fault detection method for distribution line based on current zero-crossing features | |
| CN107290625B (en) | Test device and method for lightning strike effect of optical fiber composite overhead ground wire induced by double exponential current wave | |
| GB2617883A (en) | An on-line monitoring system and a method of crack arresting via pulse current and crack state detecting using the same | |
| JP2017215937A (en) | Reactive power compensation system and method thereof | |
| CN105931823A (en) | Method for automatic tracking adjustment of resonance elimination resistor of voltage transformer | |
| CN110376472B (en) | Photovoltaic grid-connected inverter island detection method based on double-loop current negative feedback control | |
| CN107271846B (en) | Test device and method for lightning strike effect of optical fiber composite overhead ground wire induced by square wave current wave | |
| CN108964080A (en) | TSC operation/cutting method, terminal device and computer readable storage medium | |
| CN108107325A (en) | A kind of method of quick lookup threephase potential transformer failure | |
| Wang et al. | Wide Range Energy Harvesting Technique for Current Transformer Based on Coil Adaptive Switching | |
| CN204761745U (en) | A Servo Heating System | |
| CN211698048U (en) | Long-time voltage tolerance test device for direct current transfer switch lightning arrester |