Eddy current nondestructive detects the technical new application in iron and steel industry

  • Time:
  • Click:165
  • source:EDON CNC Machining
Eddy current detects as 5 great convention nondestructive detects one of methods, apply in steely industry very extensive, those who include composition of flaw detection of crackle of exhaustion of flaw detection of metallic bar, wire, structural member, material and matter content differentiate, of heat treatment condition differentiate, batch mixing a lot of respect such as the grading, thickness that measures metallic thin plate. In recent years, as detect to eddy current the development of appearance of the development that the technology understands and computer, instrument and technology of digital signal processing, eddy current nondestructive detects the technology obtained certain breakthrough in the application in iron and steel industry, to certain consider as before detect the limit or " impossible " difficult problem, found the way that settle or train of thought. For example, at present somebody raised high temperature of 1100 ℃ above imitate of blemish of surface of base of Lian Zhu board is online detect, will traditional backset detects the temperature of the object raised hundreds of degrees, and development of a company went Sweden to detect the backset of material of steel of 1000 ℃ high temperature and other metal plate, base detects equipment. In addition, the application that eddy current detects is outspread still arrived the capillary, silk material that the diameter is less than 1mm reachs stainless steel crystallizer fluid detect wait for a respect. The generation principle backset of eddy current detects is to use electromagnetism induction principle, through determining to be come to by the change of n/ele be induced by backset inside check workpiece conductor of nondestructive ground assess reachs the certain property of its workpiece, or the nondestructive that discovers flaw detects method. When coil shedding exorbitant frequency is handed in change generation of amid of the meeting when electric current is handed in change magnetic field, if this magnetic field nears metallic workpiece surface, it is in workpiece can the induction gives electric current, abbreviation backset. Dimension of the conductivity of the size of eddy current and metallic stuff, permeability, geometry and among them blemish configuration are concerned. Eddy current itself also can produce magnetic field, its intensity depends on the size of eddy current, its direction and magnetic field of coil electric current are contrary, the communication impedance of coil is formed after it and overlay of coil magnetic field. Change of eddy current magnetic field can cause the change of coil impedance, the amplitude that measures a this impedance change and phasic can measure a workpiece surface and close surface ability secondhand to pledge namely unusual or blemish dimension. Application summarizes what high temperature of 1 1000 ℃ connects blemish of surface of casting board base to detect eddy current detects the limitation of high temperature goods basically depends on probe can susceptive temperature, traditional backset detects the technology detects below high temperature condition temperature can amount to 550 ℃ , if use water-cooling probe to detect, temperature still can rise. Probe of Gu Huiming high temperature backset that uses special material development, wind of have the aid of is cold the idea that combines with water-cooling photograph, make sensor interior temperature maintains from beginning to end it is under 40 ℃ , can bear for long intense high temperature radiate. The experiment makes clear, use probe of this high temperature to be able to be opposite base of casting of 1100 ℃ above is online detect a deepness for 1.

5mm, width is 0.

3mm, grow the exterior blemish that is 10mm. This technique can restrain the noise effect that place of mark of spot of vibration of casting base surface produces effectively, and signal of computer of have the aid of handles a technology, realize surfaces of pair of base of hot condition casting to the fixed position of blemish, ration is analysed and print a record, provided technical basis to realize online to connecting casting semifinished product nondestructive to detect. Occupy data introduction again, sweden foundation of a company eddy current technology, the equipment of the steel that the design makes a kind can check 1000 ℃ to control and other metal plate and blemish of base material surface. This equipment can make sure two of rolled steel surface almost perpendicular direction scan. Use the analyzer that computer place comprises, mix the signal cent of the input for serious flaw, harmless blemish not recognize 3 kinds of main categories, can find out the position of any blemish. This device can determine accurately semifinished product apparently 0.

The nick place with dark 5mm. 2 stainless steel detect capillarily if stainless steel is capillary,leave line or online nondestructive flaw detection to diameter of extremely fine canaliculus, use electromagnetism backset to detect although the method is feasible, but must configure ability of special type probe to achieve satisfactory result. Because of capillary extremely petty canal diameter, current craft level still cannot be made inside wear probe, also cannot use the probe that choose form to undertake detecting, type probe is crossed to undertake detecting outside can be being passed only. Xi'an traffic university and Aidesen (Xiamen) electronic limited company wears probe outside the differential form that combines development, the span between the width to coil, ply, two coil, probe and capillary after the many sided such as means of the clearance between, line undertakes computation and actor are chosen, configured tailor-made advanced outside probe of the special type that wear type, when inspection frequency is 666kHz, reach Φ to Φ 1mm 0.

The stainless steel of 45mm is capillary undertake detecting, all achieved better result. 3 steel wire are online detect steel wire is online detect use two kinds of methods commonly: One kind is to rotate exploration type, namely eddy current detector circles steel wire high speed to rotate. This kind of method basically is used detect the crackle with edge fore-and-aft and outspread steel wire, scratch and the nick that pull silk. Relative to the motion at steel wire, the contrail of detector this helix shape. Use many detector paratactic high speed rotates, can achieve the examination of 100% , but the sensitivity of its surface flaw detection is finite. Maintain constant span not easily between detector and steel wire, the sensitivity when clearance increases decreases, if steel wire is prejudicial, clearance can change. Use high speed processor to be able to feel clearance automatically, undertake compensating ceaselessly, make systematic sensitivity gets rising. Another kind is to surround coil type. Steel wire is crossed from inside annular coil, transducer checks eddy current effectively to be in of a section plane distributing, contrast with a section plane, suit the crackle of blemish of test point shape and circumferential direction, have very tall sensitivity to transverse crack, V crackle, field trash, indentation and fold. Detect rate is rapid, detect diametical range is big. Surround the drive electric current of coil type explores type than rotating tall, have better deepness penetrability. Systematic stability is good, do not suffer the effect of temperature change and other factor. Nod in Courier when magnet material when 800 ℃ are the following, the meeting after magnetism is saturated makes signal is restrained, but can through adjusting magnetic field intensity avoids magnetism saturation, enhance keen sense. Use mostly at present surround coil type, also can use band of afore-mentioned two kinds of methods. Eddy current technology is in very good application received in hauling steel wire of product line of silk, oily temper, cold Dui or production of spring steel silk. Water-cooling surrounds the wire rod that coil exceeds 1100 ℃ to temperature undertakes detecting, its detect speed exceeds 500km/h. 4 fluid detect crystallizer fluid detecting accurately is fluid of the implementation in Lianzhu production process the key of automata. Fluid of molten steel of eddy current type plan have response rate fast, measure precision tall, do not need special safety to defend, installation is safeguarded convenient wait for distinct advantage, practical influence evolution very fast. Song Dongfei introduced Pan Gang to transform position control of fluid of the RAM series vortex flow that uses domestic production molten steel the circumstance of appearance. Should measure a system to use sensor of eddy current type to measure molten steel fluid, the primary coil of the sensor of supply of 50kHz high frequency signal that produces by the oscillator (incentive coil) , because suffer inside molten steel the influence of eddy current electric current, by primary coil generation is handed in change magnetic field follows fluid height changes. In secondary coil (slotted line is encircled) inside the V2 of voltage V γ that changes generation and the intensity that traverse coil magnetic field into direct proportion, thereby differential voltage (V1-V2) along with fluid height changes. Reach linearization through undertaking to V1-V2 enlarge, phasic, frequency, amplitude is analysed, those who send 16 is high-powered odd 80C196KC handles a machine, get namely at fluid height measures signal, via controlling apparatus changeover becomes signal of 4 ～ 20mA to send system of crystallizer fluid position control PLC. This control appearance measures limits to be 0 ～ 150mm, defend oneself force is 0.

1mm. Move make clear, performance of system of this fluid position control is stable and reliable, use precision amounts to ± 3mm, not only reduced crackle of casting base surface, improved product quality, and economic benefits is remarkable. CNC Milling CNC Machining