CN102818838A - Electromagnetic torque change based method for nondestructive detection of defect in conductor - Google Patents
Electromagnetic torque change based method for nondestructive detection of defect in conductor Download PDFInfo
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- CN102818838A CN102818838A CN2012102912012A CN201210291201A CN102818838A CN 102818838 A CN102818838 A CN 102818838A CN 2012102912012 A CN2012102912012 A CN 2012102912012A CN 201210291201 A CN201210291201 A CN 201210291201A CN 102818838 A CN102818838 A CN 102818838A
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Abstract
The invention relates to an electromagnetic torque change based method for nondestructive detection of defects in a conductor, and belongs to the technical fields of power, electronic industry, metallurgical industry, semiconductor material and oil energy. This method is as below: first a torque sensor is set at one side of a cylindrical permanent magnet to drive the cylindrical permanent magnet to rotate, and conductors having no defects approach the rotating cylindrical permanent magnet, so as to measure a reference curve of change of rotating angular velocity of the cylindrical permanent magnet with time; and then a plurality of calibration curves of change of rotating angular velocity of permanent magnet with defects with time are measured; the permanent magnet approaches the conductor to be measured, so as to obtain a measurement curve; and the measurement curve is compared with the calibration curves, so as to obtain defect size of the conductor to be measured. The method is suitable for conductors such as wire, tubing and sheet metal; and the conductor to be measured does not need to move, thereby simplifying measurement conditions, measurement process, measurement cost and measurement equipment; besides, the method can easily realize automation and miniaturization, and can be applied to more fields and environment.
Description
Technical field
The present invention relates to a kind of lossless detection method based on defective in the conductor of electromagnetic torque variation; Relate in particular to the detection method of defective in a kind of thin plate class, wire rod, the pipe fitting conductor, belong to electric power, electronics industry, metallurgical industry, semiconductor material, petroleum-based energy technical field.
Background technology
Metal materials such as pipe, wire rod and thin plate class possibly contain defectives such as impurity (like oxide, sulfide grain etc.) hole, crackle owing to starting material and preparation technology's reason, and this will have a strong impact on the usage performance of material.For example in electric power, electronics industry; When containing the second non-conductive phase impurity particle in the materials such as plain conductor, sheet metal, circuit board, then will reduce its electric property greatly; And reduce its physical strength; Also possibly produce extra Joule heat during work, make device overheated, be out of shape even burn circuit and electronic equipment.In metallurgical and manufacturing industry industry; Thin plate class material can be used for the housing or the encapsulating material of automobile, household electrical appliance, packaging for foodstuff, electronic product; 1 millimeter of the thickness of the thin plate class material that has even less than; To become serious mass defect if wherein contain bigger impurity, therefore be necessary very much in the thin plate production run, to carry out Quantitative Monitoring.In oil, chemical field; The pipeline of transfer oil or other chemical liquid is owing to be on active service under strong acid, highly basic or humidity mal-conditions such as (like the submarine oil pipelines) for a long time; Improper or extend service in the army as easy as rolling off a log generation galvanic corrosion or formation fatigue crack like material protection; Because required maintenance condition is inconvenience very, if fault or material failure then possibly cause catastrophic effect.Therefore develop effectively easy detection method ten minutes necessity and have national economy and science and techniques of defence meaning important, reality.For convenient the description is approximately zero impurity, hole, crackle etc. with above-mentioned conductivity and is referred to as defective.
The main method of the Non-Destructive Testing that utilizes electromagnetic principle to carry out at present has high-density electric (direct current), transient electromagnetic method, frequency domain electromagnetic methods, induced polarization method (applying frequency scope: 10
2-10
4Hz) etc.High-density electric is a kind of contact method, exists electrode contact problems application scenario less.Above-mentioned all the other methods all are to utilize alternating electric field or electromagnetic detection method, and the electromagnetism field source need be provided, and in testee, inspire secondary electrical field and magnetic field, detect according to frequency domain character or electromagnetic field characteristic.In general, equipment is more complicated all, and the volume of measuring instrument is bigger, and the ability of suitable environment is very limited.
Summary of the invention
The objective of the invention is to propose the lossless detection method of defective in a kind of conductor that changes based on electromagnetic torque, utilize the difference of conductivity between defective and the conductor, quantitatively, non-ly directly detect the defective in the conductor contiguously, and make test process simple and reliable.
The lossless detection method based on defective in the conductor of electromagnetic torque variation that the present invention proposes may further comprise the steps:
(1) side that radially magnetize at, thickness is the cylindrical permanent magnet of w is provided with a torque sensor;
(2) drive the cylindrical permanent magnet rotation, when cylindrical permanent magnet reaches an initial velocity, remove driving force, cylindrical permanent magnet is rotated further under inertia effect;
(3) cylindrical permanent magnet that makes the conductor that do not contain defective and rotation near, spacing distance is d, records the time dependent reference curve of angular velocity of rotation of cylindrical permanent magnet through torque sensor;
(4) on conductor, bore diameter do not wait and spacing distance greater than a plurality of apertures of cylindrical magnet body thickness w; With the aperture that the rotational circle cylindricality permanent magnet of step (2) does not wait near a plurality of diameters on the conductor successively, obtain the time dependent a plurality of calibration curves of angular velocity of rotation of cylindrical permanent magnet;
(5) with the rotational circle cylindricality permanent magnet of step (2) near measured conductor, obtain the time dependent measurement curve of angular velocity of rotation of a cylindrical permanent magnet;
(6) the measurement curve of step (5) and the calibration curve of step (4) are compared; If measuring curve and a calibration curve coincides; Then the flaw size of measured conductor equals and the corresponding orifice size of this calibration curve; If measure curve between adjacent two calibration curves, then the flaw size of measured conductor is between adjacent two corresponding orifice sizes of calibration curve with this.
The lossless detection method based on defective in the conductor of electromagnetic torque variation that the present invention proposes has following characteristics and advantage:
1, the inventive method is applicable to the conductor of wire rod, tubing and thin plate class, and measured conductor need not move, and has simplified measuring condition, measuring process and measurement cost, therefore simplified measurement equipment greatly;
2, the inventive method is in measuring process, and measured conductor does not directly contact with surveying instrument, is a kind of lossless detection method, and only need measure the angular velocity of rotation variation, need not measure corresponding power, so measuring process is convenient and simple;
3, the inventive method is compared with the existing lossless detection method that utilizes electromagnetic principle to carry out, and the inventive method is simple, and the detection instrument according to the inventive method design easily is automated and miniaturization, can be applied in more field and the environment.
Description of drawings
Fig. 1 is to use the synoptic diagram of the embodiment that the inventive method measures.
Fig. 2 is to use the inventive method calibration process synoptic diagram, and wherein reference curve is for containing impurity hour angle velocity varies with time curve, curve 1,2 ..., the demarcation aperture that n is corresponding is of a size of d
1, d
2..., d
n, the magnitude relationship of aperture is d
1＜d
2＜...＜d
n
Fig. 3 is to use the measuring principle synoptic diagram of the inventive method.
Among Fig. 1～Fig. 3, the 1st, cylindrical permanent magnet, the 2nd, the thin axle of the stainless steel of band taper, the 3rd, glass ceramics bracing frame, the 4th, copper post, the 5th, coupling shaft, the 6th, motor, the 7th, measured conductor, the 8th, the defective in the conductor, the 9th, faradic sensitizing range.
Embodiment
The lossless detection method that the present invention proposes based on defective in the conductor of electromagnetic torque variation, the principle schematic of embodiment is as shown in Figure 1, may further comprise the steps:
(1) side that radially magnetize at, thickness is w cylindrical permanent magnet 1 is provided with a torque sensor (not shown);
(2) drive cylindrical permanent magnet 1 rotation, when cylindrical permanent magnet 1 reaches an initial velocity, remove driving force, cylindrical permanent magnet 1 is rotated further under inertia effect; In one embodiment of the invention, adopt the method for electromagnetic induction to drive cylindrical permanent magnet 1 rotation, as shown in Figure 1, realized driving through drive the copper post 4 that rotates down at motor 6 based on the method for electromagnetic induction to cylindrical permanent magnet 1;
(3) cylindrical magnet 1 body that makes the conductor that do not contain defective and rotation near, spacing distance is d, records the time dependent reference curve of angular velocity of rotation of cylindrical permanent magnet through torque sensor, and is as shown in Figure 2;
(4), make following calibration experiment in advance for the quantitative measurment flaw size: on conductor, bore diameter do not wait and spacing distance greater than a plurality of apertures of cylindrical magnet body thickness w, to simulate the not defective of equidimension.The aperture that respectively the rotational circle cylindricality permanent magnet 1 of step (2) is not waited near a plurality of diameters on the conductor successively obtains the time dependent a plurality of calibration curves of angular velocity of rotation of cylindrical permanent magnet; Because aperture is big more, the electromagnetic force of being responded to is more little, and the suffered moment of torsion of magnet is more little.Angular velocity of rotation is decayed slack-off in time.For example hole diameter is d
1＜d
2＜...＜d
n, then measured curve will be respectively 1,2 ..., n;
(5) with the rotational circle cylindricality permanent magnet 1 of step (2) near measured conductor 7, obtain the time dependent measurement curve of angular velocity of rotation of a cylindrical permanent magnet;
(6) the measurement curve of step (5) and the calibration curve of step (4) are compared; If measuring curve and a calibration curve coincides; Then the flaw size of measured conductor equals and the corresponding orifice size of this calibration curve; If measure curve between adjacent two calibration curves, then the flaw size of measured conductor is between adjacent two corresponding orifice sizes of calibration curve with this.
Ultimate principle of the present invention is following:
Shown in Fig. 3 (a), cylindrical rotating permanent magnet 1 forms rotating magnetic field around it, and the conductor of being surveyed 7 is in rotating magnetic field incised magnetic line of force portion's generation within it induction current, and induction current and magnetic field interaction produce Lorentz force in conductor.The cylindrical permanent magnet 1 of 7 pairs of rotations of conductor of being surveyed according to Newton third law (action-reaction law) produces the acting force of opposite sign but equal magnitude; The electromagnetic torque that is produced hinders rotatablely moving of cylindrical permanent magnet 1; Make the decay of cylindrical permanent magnet 1 rotational speed until stopping i.e. electromagnetic braking process.Shown in Fig. 3 (b); The induction current that when above-mentioned conductor 7 contains defective 8 (defective is non-conductive), is produced in the said process reduces; And then the electromagnetic force that produces also reduces; Corresponding electromagnetic torque also reduces, this reducing on the time dependent curve of angular velocity of rotation that process can be reflected to cylindrical permanent magnet 1, and this curve negotiating electromagnetic sensor can be measured.Like this, can release the size and the distributed intelligence of defective 8 in the electric conductor 7 through this curvilinear motion.
The present invention is applicable to the detection of non-conductive impurity in pipe, line, the thin plate class electric conductor or defective, because the thickness of above-mentioned material is less, conductor object to be detected can be easy to satisfy the electromagnetism infiltration condition: measure thickness less than the skin layer thickness that becomes; In addition, the influence of difference also can be very little between aperture that demarcation is adopted and the defective, can ignore.
Ultimate principle according to the invention described above is described further the present invention:
Guaranteeing under the situation safe in utilization more little good more between the cylindrical permanent magnet 1 and measured conductor 7,, and then obtain stronger measuring-signal in the hope of the stronger magnetic field of acquisition in measured conductor 7 apart from d.
Shown in Fig. 3 (a), the induction current that the cylindrical permanent magnet 1 of rotation produces in measured conductor 7 has an areal concentration territory, claims that this zone is faradic sensitizing range 9., defective 8 could obtain its dimension information when being positioned at faradic sensitizing range 9.Shown in Fig. 3 (b), faradic sensitizing range 9 should adapt with flaw size: faradic sensitizing range 9 should be too not big, otherwise the measured angular velocity that contains defective 8 curve and reference curve difference are not obvious over time; Faradic sensitizing range 9 should be too not little yet, otherwise defective 8 has exceeded the scope of faradic sensitizing range 9 when measuring, and measurement will can not get defective dimension information accurately.
Above-mentioned faradic sensitizing range 9 is roughly suitable with the thickness of cylindrical permanent magnet 1, so the thickness of cylindrical permanent magnet 1 has determined by the minimum and maximum resolution of detecting defects 8.The thickness of cylindrical permanent magnet 1 generally elect as be slightly larger than to detect the nominal size of defective; The also relevant relation of diameter of faradic sensitizing range 9 and cylindrical permanent magnet 1.
For making cylindrical permanent magnet 1 obtain an initial angle speed distinct methods can be arranged, as adopting Mechanical Driven, survey is carried out above-mentioned measuring process again except that driving force then.Adopted the electromagnetic induction method of driving in the embodiment in figure 1.Be provided with a cylindrical, copper post 4 that axis is in parallel in the side of cylindrical permanent magnet 1, cylindrical, copper post 4 links to each other with motor 6 through coupling shaft 5.Concrete measurement procedure is following: drive through motor 6 and make 4 rotations of copper post; Be in the copper post 4 acquisition induction currents of the rotation in the magnetic field that cylindrical permanent magnet 1 produces; Cylindrical, copper post 4 receives induction current and the action of a magnetic field produces Lorentz force, and its reacting force drives cylindrical permanent magnet 1 rotation.Treat cylindrical permanent magnet 1 reach certain rotating speed and steadily after, withdraw copper post 4 and the motor 6 that is attached thereto fast, make cylindrical permanent magnet 1 obtain certain initial angle speed, and under inertia effect, keep rotation.
In the embodiment in figure 1, in order to reduce the friction force between cylindrical permanent magnet 1 and the bracing frame 3 as far as possible, bracing frame 1 has adopted glass ceramic material, and thin axle 2 adopts the stainless steel rod structure of double headed roller taper.On bracing frame 3, process the concave shaped duck eye with fixing thin axle 2, above-mentioned measure can be eliminated the influence of friction force to measuring process basically.
Claims (1)
1. the lossless detection method of defective in the conductor that changes based on electromagnetic torque is characterized in that this lossless detection method may further comprise the steps:
(1) side that radially magnetize at, thickness is the cylindrical permanent magnet of w is provided with a torque sensor;
(2) drive the cylindrical permanent magnet rotation, when cylindrical permanent magnet reaches an initial velocity, remove driving force, cylindrical permanent magnet is rotated further under inertia effect;
(3) cylindrical permanent magnet that makes the conductor that do not contain defective and rotation near, spacing distance is d, records the time dependent reference curve of angular velocity of rotation of cylindrical permanent magnet through torque sensor;
(4) on conductor, bore diameter do not wait and spacing distance greater than a plurality of apertures of cylindrical magnet body thickness w; With the aperture that the rotational circle cylindricality permanent magnet of step (2) does not wait near a plurality of diameters on the conductor successively, obtain the time dependent a plurality of calibration curves of angular velocity of rotation of cylindrical permanent magnet;
(5) with the rotational circle cylindricality permanent magnet of step (2) near measured conductor, obtain the time dependent measurement curve of angular velocity of rotation of a cylindrical permanent magnet;
(6) the measurement curve of step (5) and the calibration curve of step (4) are compared; If measuring curve and a calibration curve coincides; Then the flaw size of measured conductor equals and the corresponding orifice size of this calibration curve; If measure curve between adjacent two calibration curves, then the flaw size of measured conductor is between adjacent two corresponding orifice sizes of calibration curve with this.
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|---|---|---|---|
| CN201210291201.2A CN102818838B (en) | 2012-08-15 | 2012-08-15 | Electromagnetic torque change based method for nondestructive detection of defect in conductor |
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| CN201210291201.2A CN102818838B (en) | 2012-08-15 | 2012-08-15 | Electromagnetic torque change based method for nondestructive detection of defect in conductor |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1061698A (en) * | 1996-08-16 | 1998-03-06 | Tokyo Buhin Kogyo Kk | Braking torque detecting device of drum brake |
| WO2000058704A1 (en) * | 1999-03-26 | 2000-10-05 | Fast Technology Ag. | Torque and speed sensor |
| CN202196038U (en) * | 2011-08-12 | 2012-04-18 | 西安思坦仪器股份有限公司 | High-resolution electromagnetic flaw detector and control system |
-
2012
- 2012-08-15 CN CN201210291201.2A patent/CN102818838B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1061698A (en) * | 1996-08-16 | 1998-03-06 | Tokyo Buhin Kogyo Kk | Braking torque detecting device of drum brake |
| WO2000058704A1 (en) * | 1999-03-26 | 2000-10-05 | Fast Technology Ag. | Torque and speed sensor |
| CN202196038U (en) * | 2011-08-12 | 2012-04-18 | 西安思坦仪器股份有限公司 | High-resolution electromagnetic flaw detector and control system |
Non-Patent Citations (2)
| Title |
|---|
| 宋庆红: "《焊缝小角度裂纹缺陷的磁轭法检测》", 《无损检测》 * |
| 闻凤连等: "《新型磁传感器理论及其在钢板缺陷检测的应用》", 《仪表技术与传感器》 * |
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