CN2888445Y - Multi-pole excitation field generator for non-destructive testing of sample by scanning - Google Patents

Abstract

The utility model discloses a nondestructive testing samples scanning multi-polar inspiration field device, the core of inspiration coil is made in docking condition by four high magnetic conductivity of Po Mo alloy(1 J85) leaves, each leave is U-shaped, angle 90 degree, the referred leaves include a bottom, a vertical and a horizontal edge ,the vertical edge and bottom edge is mutual vertical, the angle of horizontal and vertical side edge is 120 degree to 160 degree, the top end of four cross edges has proper spacing distance; the insulation works among the above referred leaves, a winding enameled wire is on the vertical leaf edge and the bottom leaf edge , the enameled wire winding is opposite direction on the two adjacent leaves, the utility model is inspired by quadruple inspiration coil instead of double D-type coil, and has the ability to measure flawed deeply, and also has the following advantages:(1) field attenuation happens faster with space, little noise;(2) the more balance is at the SQUID device;(3) a magnetometer is the only need(omit the gradiometer), so that the device technology can be greatly simplified.

Description

Scanning samples Non-Destructive Testing multiple encourage field generating means

Technical field

The utility model relates to a kind of SCANNING SQUID or forms the technical field of multipole nondestructive detection system by other magnetic sensitive element, comprising the sensitive element balance, reduces neighbourhood noise and to the technical matterss such as resolution of defective in the sample.

Background technology

In superconductor technology research, the SCANNING SQUID Non-Destructive Testing has a wide range of applications, and is to have development potentiality.Non-Destructive Testing is the widely used a kind of the methods whether tested article of destructive discriminating exist defective of not having in fields such as material, machinery, aviation, though the method for Non-Destructive Testing at present is a lot, for example ultrasound examination, X ray detection, thermal wave detection, EDDY CURRENT etc., but each method all has limitation, along with the continuous development of industrial technology, new detection means is also being brought in constant renewal in.The SQUID Non-Destructive Testing is the representative of this novel detection technique just, because its high spatial resolution (200 μ m) and to the high sensitivity that deep zone defect detects makes it may become a kind of detection method that has potentiality.Therefore this detection method is utilized the SQUID sensing element, and the identification to defective is to be based upon on the corresponding relation in defective and magnetic field, has usually that two kinds of situations are suitable uses this detection method, and a kind of is detection to static magnetic field, and a kind of is detection to the vortex field.The local damage of some material is as after scratch, fatigue, depression damage or being subjected to external force effect generation strain, can produce the residual magnetic field, generally be subjected to stress big more, the residual magnetic field of generation is also big more, therefore just can judge the degree that damage of material is hindered by measuring this DISTRIBUTION OF MAGNETIC FIELD.EDDY CURRENT is a kind of important means in the conventional Non-Destructive Testing.But SQUID has higher sensitivity and detects the degree of depth than conventional EDDY CURRENT the detection of vortex field, and for example to surpassing the defective of the 26mm degree of depth, conventional Non-Destructive Testing is helpless.Use SQUID and detect the vortex field imaging, this method can be widely used in surface imperfection or the deep zone defect that detects in the no magnetic conductor material.When electromagnetic wave is propagated in conductor, according to distracted law, to produce eddy current in the conductor, the distribution of eddy current and size are relevant with the conductive characteristic of conductor, if there is defective in the conductor, this defective will have a strong impact on the electric conductivity of conductor, if for example have the crack in the conductor block, can walk around the crack when eddy current flows and redistribute in conductor, therefore, just can obtain the information of relevant defective by detecting the magnetic field that eddy current produced of redistribution.In experiment, the electromagnetism excitation coil of coiling is two D molded lines circles, i.e. gradient coil, it by symmetry and around constituting (coil that also can select other types for use), for example circular coil or quadrupole coil etc. to two opposite semicircular ring.When sample is scanned in the middle of SQUID and solenoid, the border of sample and exist the position of defective, the distribution of vortex flow to change to some extent, the Distribution of Magnetic Field that SQUID detects also is vicissitudinous, and the signal that does not have other positions of defective in these signals and the sample is differentiated.Because electromagnetic wave is propagated in material and is had skin effect, and electric current is exponential damping to conductor inside: J=j _se ^{-d/ δ}, wherein δ is a skin depth, and its physical meaning is an electromagnetic wave when material surface enters into the conductor degree of depth and is δ, and the electromagnetic wave amplitude is reduced to and is originally 1/e, its phase change π.Because the square root of skin depth δ and frequency f is inversely proportional to, $\mathrm{\δ}=503/\sqrt{\mathrm{f\μ\σ}},$ Wherein μ and σ are respectively the magnetic permeability and the conductivity of conductor material, therefore if the darker defective of detection must use the lower frequency that excites, yet gradient coil is difficult to satisfy such requirement.

The utility model content

At the problem of above-mentioned existence, the purpose of this utility model is to provide a kind of scanning samples Non-Destructive Testing multiple encourage field generating means, and this device can be surveyed darker defective.

For achieving the above object, the magnetic core of a kind of scanning samples Non-Destructive Testing of the utility model multiple encourage field generating means drive coil adopts 4 permalloy (1J85) blade butt joints with high magnetic permeability to make, every blade is the U type, angle is 90 °, described blade comprises base, vertical edge and horizontal edge, the base is vertical mutually with vertical edge, and the angle of horizontal edge and vertical edge is 120 °～160 °, at interval suitable distance between the top of 4 horizontal edges; Mutually insulated between the described blade is wound with enameled wire on the base of blade and the vertical edge, and the enameled wire winding direction on adjacent two blades is opposite.

Further, described blade comprises one deck at least.

The utility model adopts four utmost point excitation variable windings to replace two D molded lines circles, and can measure darker defective, and have following advantage: 1. the field is faster with spatial attenuation, so noise is little; 2. in the easier balance in SQUID device place; 3. only need a magnetometer (having saved gradiometer) to get final product, device technology is simplified greatly.

Description of drawings

Fig. 1 is the structural representation of the utility model magnetic core.

Fig. 2 is the shape of each mounted blade of the utility model magnetic core.

Fig. 3 is the direction synoptic diagram in the magnetic field that direction of current and electric current produce in the coil in the exciting field.

Fig. 4 is a SCANNING SQUID non-destructive testing experimental device theory diagram.

Embodiment

Core of the present utility model is the drive coil that replaces circular or two D types commonly used with multiple encourage coil (four pole excitation coils), is used for the Non-Destructive Testing experiment of high temperature DC SQUID.

As shown in Figure 1, the magnetic core of the utility model drive coil adopts 4 permalloy (1J85) blade 1 butt joints with high magnetic permeability to make, every blade 1 is the U type, angle is 90 °, blade 1 comprises base 2, vertical edge 3 and horizontal edge 4, base 2 is vertical mutually with vertical edge 3, and horizontal edge 4 is 120 °～160 ° with the angle of vertical edge 3, at interval suitable distance between the top of 4 horizontal edges 4; Mutually insulated between the blade 1 is wound with the enameled wire (not shown) on the base 2 of blade 1, the vertical edge 3, and the enameled wire winding direction on adjacent two blades 1 is opposite, thereby the pole orientation that forms adjacent two blades is opposite.The concrete practice is as follows:

Fig. 2 is the shape behind the magnetic core mounted blade of four pole excitation coils, and material is the permalloy (1J85) with high magnetic permeability, designs three different coils respectively, and the size of its blade is respectively 2 * 2.4 * 0.4mm ³, 14 * 13 * 1.6mm ³, 25 * 22 * 1.6mm ³(a * b * h, h are the thickness of magnetic core) three kinds, wherein first is the individual layer magnetic core, latter two is 4 layers of magnetic core.

After carrying out stereo magnetic core support, coiling enameled wire on four blades according to a certain direction, direction of winding on adjacent two blades is opposite, and to make wire resistor big as far as possible, so that and the oscillator output resistance of lock-in amplifier coupling, four pole excitation coils of our development be that the No1. diameter is that 0.13mm is around being of a size of 2 * 2.4 * 0.4mm ³Magnetic core on, the number of turn of each blade is 40 circles; No2. be that the enameled wire of 0.06mm is wound on and is of a size of 14 * 13 * 1.6mm with diameter ³Magnetic core on, the number of turn of each blade is 700 circles; No3. be that the enameled wire of 0.06mm is wound on and is of a size of 25 * 22 * 1.6mm with diameter ³Magnetic core on, each blade 800 circle; In this process, to guarantee blade and around the insulation between the top enameled wire, and the coiling multiturn of will trying one's best makes its resistance big as far as possible, certain resistance of connecting is connected with coaxial cable, substantially accomplish to be complementary with the output resistance of lock-in amplifier oscillator, to solidify with epoxy sealing at last, and with packaged drive coil surface finish polishing, in order to using.Fig. 3 is the direction synoptic diagram in the magnetic field that direction of current and electric current produce in the coil in the exciting field.

Fig. 4 is a SCANNING SQUID non-destructive testing experimental device theory diagram.It comprises computer control and data handling system 10, XY scans micro-step motor 14, four pole excitation coils 15, fixing and the adjusting platform 16 of drive coil 15, SQUID measuring sonde 18, lock-in amplifier 11, low temperature liquid nitrogen Dewar 13, sample 17 to be scanned and print feeler lever and high temperature SQUID electronic system 12; Record in the computing machine 10 behind signal process SQUID electronic system 12 that SQUID18 detects and the lock-in amplifier 11,14 drives of simultaneous computer 10 control step motors are scanned sample 17 and do two dimensional motion, so just can write down the Distribution of Magnetic Field in the certain limit.

Claims (2)

1, a kind of scanning samples Non-Destructive Testing multiple encourage field generating means, it is characterized in that, the magnetic core of drive coil adopts 4 permalloy blade butt joints with high magnetic permeability to make, every blade is the U type, angle is 90 °, and described blade comprises base, vertical edge and horizontal edge, and the base is vertical mutually with vertical edge, the angle of horizontal edge and vertical edge is 120 °～160 °, at interval suitable distance between the top of 4 horizontal edges; Mutually insulated between the described blade is wound with enameled wire on the base of blade and the vertical edge, and the enameled wire winding direction on adjacent two blades is opposite.

2, a kind of scanning samples Non-Destructive Testing multiple encourage according to claim 1 field generating means is characterized in that described blade comprises one deck at least.

Images