Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
  • G01N29/04—Analysing solids
  • G01N29/041—Analysing solids on the surface of the material, e.g. using Lamb, Rayleigh or shear waves
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
  • G01N29/04—Analysing solids
  • G01N29/043—Analysing solids in the interior, e.g. by shear waves
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
  • G01N29/22—Details, e.g. general constructional or apparatus details
  • G01N29/223—Supports, positioning or alignment in fixed situation
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
  • G01N29/22—Details, e.g. general constructional or apparatus details
  • G01N29/24—Probes
  • G01N29/2412—Probes using the magnetostrictive properties of the material to be examined, e.g. electromagnetic acoustic transducers [EMAT]
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
  • G01N29/22—Details, e.g. general constructional or apparatus details
  • G01N29/26—Arrangements for orientation or scanning by relative movement of the head and the sensor
  • G01N29/265—Arrangements for orientation or scanning by relative movement of the head and the sensor by moving the sensor relative to a stationary material
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
  • G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
  • G01N29/4409—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by comparison
  • G01N29/4436—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by comparison with a reference signal
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N2291/00—Indexing codes associated with group G01N29/00
  • G01N2291/02—Indexing codes associated with the analysed material
  • G01N2291/023—Solids
  • G01N2291/0234—Metals, e.g. steel
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N2291/00—Indexing codes associated with group G01N29/00
  • G01N2291/04—Wave modes and trajectories
  • G01N2291/042—Wave modes
  • G01N2291/0423—Surface waves, e.g. Rayleigh waves, Love waves
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N2291/00—Indexing codes associated with group G01N29/00
  • G01N2291/10—Number of transducers
  • G01N2291/102—Number of transducers one emitter, one receiver
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N2291/00—Indexing codes associated with group G01N29/00
  • G01N2291/26—Scanned objects
  • G01N2291/263—Surfaces
  • G01N2291/2632—Surfaces flat
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N2291/00—Indexing codes associated with group G01N29/00
  • G01N2291/26—Scanned objects
  • G01N2291/263—Surfaces
  • G01N2291/2634—Surfaces cylindrical from outside

Definitions

• the invention relates to the field of non-destructive testing, and in particular to means for ultrasonic (US) flaw inspection.
• the main field of application of the technical solution is the industrial production of continuously cast billets, including slab and bloom (objects of inspection), intended for the manufacture of widely used metal rolling groups.
• Inspection of the quality of billets for the manufacture of rolled metal at metallurgical enterprises is usually carried out on the basis of a statistical analysis of the influence of technological processes and the design parameters of continuous casting machines on the performance of rolled metal, or they use visual measuring control (VIC).
• VIC visual measuring control
• mathematical modeling and VIC do not always have acceptable reliability, which can lead to the receipt of defective billets in the production of high-quality, sheet or pipe metal products. 16 000005
• the known method consists in the fact that the metal surface is irradiated with laser pulses to generate Rayleigh waves and sounding by these discontinuity waves.
• a magnetic field is applied to the test object and the magnetic flux modulated by the ultrasound wave is recorded by the discontinuity.
• the depth, orientation and opening of the discontinuity are judged by the amplitude, polarization of the transformed ultrasonic wave and the variable component of the scattered magnetic flux. Diagnostics of surface defects of any configuration are carried out by changing the relative position of the electro-acoustic transducers and optical fibers, through which laser radiation pulses are sent to the metal surface.
• the device comprises electro-acoustic transducers, a pulsed laser generator, at least one optical fiber and a unit for measuring informative parameters.
• the disadvantages of the known technical solution include its applicability only for ultrasonic testing of metal, which is characterized by a fine-grained structure with uniform properties in thickness. Therefore, the use of this technical solution for ultrasonic testing of inspection objects will lead to low reliability and reliability of the results of ultrasonic inspection, which does not meet the existing needs of metallurgical enterprises.
• Another disadvantage of the known technical solution is the susceptibility to inspection errors due to changes in the speed of propagation of ultrasonic waves during cooling of the inspection objects, the limitation on the surface temperature of the inspection objects, which is of great importance in industrial production.
• the known solution has a limit on the volume of ultrasonic testing and is limited by the ability to inspect objects only with a flat surface, is able to provide insufficiently high inspection performance due to the low limit repetition rate of laser pulse emission, limited in practice to 500 Hz, compared with a high repetition rate, up to 8000 Hz, ultrasonic pulses of conventional electro-acoustic transducers and the need to change the relative positions of electro-acoustic transducers and optical fibers in process of scanning, periodic adjustment of optical equipment.
• the known technical solution is not able to provide an acceptable level of reliability of the inspection due to false signals occurring at the receiving transducers due to the presence of regular irregularities on the surface of the inspection object that have arisen as a result of the technological process, which leads to unreasonable rejection of the inspection object.
• the technical task is to increase the reliability and reliability of ultrasonic inspection of continuously cast billets, including slab and bloom, for the presence of RPD in production conditions.
• the provided positive effect consists, in relation to the technical solution in accordance with RU 2262689 C1, in providing the practical possibility of ultrasonic testing of the inspection object, while:
• the method of ultrasonic inspection of the object of inspection for the presence of DFD includes acoustic scanning the metal object of inspection and comparing the level of the received echo signal with the rejection level, while surface ultrasound waves of the Rayleigh type are emitted and received according to a separate switching circuit of the generator and receiver by the echo-pulse method with the frequency of ultrasonic vibrations sufficient to detect the RPD.
• the distance between the generator and the receiver is selected from condition (1).
• d is the distance between the transducers.
• the reference signal is periodically formed, which is a surface ultrasonic wave of the Rayleigh type propagating directly from the generator to the receiver along the shortest path between them.
• the rejection level is set based on the current amplitude value of the specified reference signal.
• the rejection level is set equal to the difference between the current value of the amplitude of the reference signal and the proportionality coefficient between the amplitudes of the reference signal and the echo signal from the SPD.
• the reference signal is used as a test signal.
• direct or inverse or residual reverse ultrasonic radiation of the generator is recorded as a reference signal in the same cycle as the echo signal from the RPD.
• a reference signal is generated by radiating or receiving ultrasound in the opposite direction in a clock cycle, which is complementary to the beat in which the echo from the opposition is recorded.
• the generator-receiver pair is placed from conditions (2) and (3) on a narrow or wide face of the inspected object, depending on the design the performance of the rolling table.
• S is the distance between the edge of the object of inspection and the center of the nearest transducer along the axis of the generator-receiver.
• the device for ultrasonic inspection of inspection objects for the presence of DFD contains at least one pair of EMAT, a functional unit for ultrasonic inspection by an echo-pulse method with a frequency of ultrasonic vibrations sufficient to detect the DFD of the inspection objects, a functional unit for forming a reference signal, a technical means for controlling and processing measurement information.
• the transducers are configured to function as a generator and receiver of surface ultrasonic waves of the Rayleigh type and are electrically connected to the technical means for controlling and processing the measurement information through these functional units.
• the converters are included in a separate control circuit.
• the functional unit for generating the reference signal and the technical means for controlling and processing the measurement information are configured to generate the reference signal in the same cycle in which the echo signal from the RPM is recorded.
• the generator is made with one active element (Fig. 8) or the receiver is made with one active element (Fig. 6).
• the functional unit for generating the reference signal and the technical means for controlling and processing the measurement information are configured to generate the reference signal in an additional clock cycle, in which the echo signal from the RPM is recorded.
• the generator is made with two active elements (Fig. 10) or the receiver is made with two active elements (Fig. 3).
• the technical means for controlling and processing the measurement information is configured to set the rejection level as the difference between the current value of the amplitude of the reference signal and the proportionality coefficient between the amplitudes of the reference signal and the echo signal from the defect.
• EMAT was used as each of the converters.
• the distance between the transducers is selected from condition (1).
• FIG. 1 flaw detector for ultrasonic inspection in the process of scanning the upper surface of the inspection object.
• FIG. 2 simplified structural and functional diagram of a device for ultrasound inspection.
• FIG. 3 the first control circuit, multi-cycle, the reference signal is formed in an additional cycle, receiving radiation in the opposite direction, while the receiver with two active elements, plan view.
• FIG. 4 A-scan of the useful signal for the first control circuit.
• FIG. 5 A-scan of the reference signal for the first control circuit.
• FIG. 6 second control circuit, single-cycle, as a reference signal, the residual direct radiation is recorded by a receiver with one active element, plan view.
• FIG. 7 A-scan of the reference and useful signals for the second control circuit.
• FIG. 8 third control circuit, single-cycle, as a reference signal, the residual backward radiation is recorded by a receiver with one active element, plan view.
• FIG. 9 A-scan of the reference and useful signals for the third control circuit.
• FIG. 10 fourth control circuit, multi-cycle, a generator with two active elements, form a reference signal, radiating in the opposite direction in an additional clock cycle, plan view.
• FIG. 11 A-scan of the useful signal for the fourth control circuit.
• FIG. 12 A-scan of the reference signal for the fourth monitoring circuit.
• FIG. 13 Schematic representation of the active elements of EMAT.
• FIG. 14 and 15 Unidirectional direct emission of EMAT.
• FIG. 16 and 17 Unidirectional backward emission from EMAT.
• FIG. 18 Bidirectional EMAT radiation.
• FIG. 19 the location of the scan node on the verge of the object of inspection during the inspection of the ribs and rib zones, plan view.
• FIG. 20 location of the scanning unit during inspection of the rib and rib zone, plan view.
• FIG. 21 location of the scanning unit during inspection of longitudinal defects, plan view.
• FIG. 22 location of the scanning unit for ultrasonic inspection of transverse defects, plan view.
• FIG. 23 preferred ultrasound inspection algorithm for tuning sensitivity by amplitude method.
• FIG. 24 design of a scanning unit for horizontal surfaces.
• FIG. 25 construction of a scanning unit for horizontal surfaces, sectional side view.
• FIG. 26 side view of the scanning unit on the upper face of the inspection object.
• FIG. 27 the scanning unit of vertical surfaces is located on the narrow side of the object of inspection.
• FIG. 28 scanning unit on the side face of the inspection object, side view.
• the implementation of the invention is shown on the example of ultrasonic inspection of the object of inspection of the slab.
• the object of inspection 1 is fed into the control zone in a horizontal position along the rolling table 2 (Fig. 1).
• Automation sets flaw detector for ultrasound inspection to its original position and begins scanning the object of inspection 1 by sounding it with ultrasound waves 3 for ultrasound monitoring and diagnostics. Based on the results, a decision is made on whether the inspection object 1 meets the established quality requirements for the manufacture of rolled products.
• the device for ultrasonic inspection contains a scanning unit 4, coordinate hardware 5 for positioning and moving the scanning unit 4 relative to the object of inspection 1, an electronic unit 6 for digital computing, generation, amplification and other processing of electrical signals.
• the node 4 contains at least one pair of EMAT 7 and 8 (Fig. 2), which are respectively the generator and receiver of surface ultrasonic waves of the Rayleigh type.
• EMAP 7 is made with one or two active elements, depending on the intended mode of operation of the device. One active element provides bidirectional radiation / reception, two active elements provide unidirectional radiation / reception, respectively, EMAT is bidirectional or unidirectional. In this case, simple high-frequency coils can be used (Hirao M. EMATS for science and industry: nincontacting ultrasonic measurements.
• the technical means 5 is made in the form of a beam structure with two guides and electromechanical drives for moving the scanning unit 4 in the immediate vicinity of the upper face of the inspection object 1 (Fig. 1).
• the electronic unit 6 contains a functional unit 9 for ultrasonic testing of the inspection object 1 by an echo-pulse method, functional unit 10 for generating a reference signal, technical means 11 for controlling and processing measurement information, as well as a display 12 for displaying information (Fig. 2) or other visualization means.
• the scanning unit 4 is rigidly connected to the supporting elements of the technical means 5.
• the electronic unit 6 is electrically connected to the scanning unit 4 and the electromechanical drives of the technical means 5.
• EMAT 7 and 8 are acoustically interconnected through the body of the inspection object 1.
• Input EMAT 7 is electrically connected to the output of the functional node 9, and the output of the EMAT 8 is electrically connected to the inputs of the functional nodes 9 and 10.
• the nodes 9, 10 are independently connected with the technical means 11 for controlling and processing the measurement information in parallel electric inclusion.
• EMAT 7 and 8 are separated in space for inclusion according to a separate control scheme from condition (1), while their working surfaces are parallel to the upper face of the inspection object 1. EMAT 7 and 8 are separated from the surface of the inspection object 1 by an air gap to protect EMAT 7, 8 from mechanical and thermal damage.
• the technical means 5 is configured to position and move the scanning unit 4 relative to the object of inspection 1 from conditions (2) to (5) to ensure full coverage of the working area of the scanning unit 4 of the entire front surface of the object of inspection.
• the functional unit 9 for ultrasound inspection is made with the possibility of sounding the object of inspection 1 with a frequency of ultrasonic vibrations sufficient to detect DFD.
• control and processing of measurement information is configured to clock the operation of the device, control the operation of nodes 9 and 10, calculate the proportionality coefficient between the amplitudes of the reference signal and the echo signal from the defect, set the rejection level equal to the difference between the current value of the amplitude of the reference signal and the specified coefficient, and comparing the received useful echo with a given rejection level.
• the ultrasound inspection Before starting the ultrasound inspection, they test the operability of the acoustic path of the device and adjust its sensitivity. The operability of the acoustic path and the presence of the acoustic contact are checked by displaying the reference signal on the display 12.
• the sensitivity can be adjusted by the amplitude method, relative to the reference signal, taking into account the proportionality coefficient, or using an artificial reflector, the size of which is equivalent in reflectivity to the defect that needs to be detected.
• the scanning unit 4 With the amplitude method, the scanning unit 4 is installed on the upper face of the object of inspection 1, they achieve stability of the reference signal on the display 12 and set the rejection level. Using an artificial reflector, the scanning unit 4 is set so as to obtain the maximum amplitude of the echo signal from the artificial reflector, after which the appropriate rejection level is set.
• the EMATs 7–8 are arranged in series with respect to the RPM 13, the centers of the EMAP 7, 8, and the RPM 13 are on the same line in the plan.
• the receiver 8 is located between the generator 7 and the RPM 13.
• the receiver 8 has two active elements that provide unidirectional reception of radiation. In this case, the formation of the reference signal is carried out in an additional cycle to the cycle in which the echo signal from the RPM 13 is recorded.
• the second control circuit differs from the first circuit in that the receiver 8 has one active element providing bi-directional radiation reception. In this case, the formation of the reference signal is carried out in the same cycle as the registration of the reflected radiation from the OPD 13.
• the generator 7 is located between the receiver 8 and the OPD 13 and has one active element providing bi-directional radiation of the ultrasonic wave, in this case, the generator 7 emits in one cycle the ultrasonic wave to search for RPM 13 and to generate a reference signal.
• the difference of the fourth control circuit (Fig. 10) from the third circuit is the operation of the generator.
• Generator 7 has two active elements providing unidirectional radiation of the ultrasonic wave and the generator 7 emits in one cycle the ultrasonic wave to search for RPM 13 and in an additional cycle for the formation of the reference signal.
• a multi-cycle radiation circuit is used (Fig. 10).
• Direct scanning is carried out in the process of scanning the object of inspection in a cycle to search for RPD 13 (Figs. 14 and 15), while the electrical signal for generating a probe pulse is first supplied to the first active element 14, then to the second active element 15 with a time shift At of the probe pulses 16, 17.
• the emitted pulses in the forward direction from the two active elements 14, 15 are in-phase added and due to interference, the amplitude of the signal 18 increases, while the beginning of the emission of the pulse 17 has a time delay At relative to the probe pulse 16.
• the radiation in the opposite direction is residual and the pulses from the two active elements 14, 15 due to the interference is weakened (signal 19), while the radiation of the pulse has a time delay At relative to the probe pulse.
• the radiation is carried out in the opposite direction (Figs. 16 and 17), while the electrical signal to create a probe pulse is first supplied to the second active element 15, and then to the first active element 14 with such the same time shift At of the probe pulses as in direct radiation. Due to interference, the emitted pulses by the active elements and in the opposite direction are added in phase and the amplitude of the signal 20 increases, and the amplitude of the radiation 21 decreases in the forward direction, while the beginning of the radiation of the pulse 16 has a time delay ⁇ relative to the probe pulse 17.
• the receiver 8 has two active elements (Fig. 3).
• a multi-cycle radiation receiving circuit is used.
• the active elements 14, 15 of the receiver 8 are also shifted in space relative to each other by d / 2 (Fig. 13), and in this case, the receiver 8 in the forward direction receives the reflected radiation from the OPD 13 first to the first active element 14, and then to the second active element 15, while the receiver 8 contains a delay line and an adder of the received signals.
• the signal is first received from the second element 15, and then from the first element 14, the direction of reception is reversed, delay and summation are realized.
• a single-cycle radiation scheme is implemented (Fig.
• the generator 7 that is, the generator 7 has one active element 14
• bi-directional radiation is carried out in the same clock cycle to search for the RPM 13 and to generate the reference signal.
• the emitted pulses 22, 23 propagate in both directions, that is, in the direction of the SPD 13 and in the direction of the receiver 8 and have the same intensity (Fig. 18).
• a one-cycle receiving circuit is used and bi-directional reception is carried out in the same radiation cycle from the PDD 13 and radiation from the generator 7 to form the reference signal.
• control signals from the technical means 11 are fed to the electromechanical drives of the technical means 5 for positioning the node 4.
• the generator-receiver pair is placed from conditions (2) , (3) according to the circuit shown in FIG. 19 or 20. Both schemes are applicable for inspection without compromising reliability.
• the generator-receiver pair is placed from condition (4), and during control the face of the object of inspection 1 for the presence of an RPD of lateral orientation (Fig. 22), the generator-receiver pair is placed from condition (5).
• circuits with a reverse arrangement of the generator 7 and receiver 8 relative to the face of the object of inspection 1 are also possible.
• a pulsed probe signal is sent by means of a generator 7, which generates a surface ultrasonic wave of Rayleigh type propagating in the scanning direction of the inspection object 1 and towards the receiver 8.
• a reference signal direct or reverse or residual reverse ultrasonic radiation of the generator 7 is recorded in the same the step that the reflected signal from the RPM 13, or in an additional step, form a reference signal, emitting or receiving in the opposite direction.
• the acoustic scanning of the object of inspection 1 is carried out by an echo-pulse method, based on the sounding of the object of inspection by ultrasonic pulses and registration of their reflections from the SPD, while surface ultrasonic waves of the Rayleigh type are reflected from the SPD 13 in the object of inspection 1, and the frequency of the ultrasonic vibrations is selected from the conditions for detecting the SPD given size.
• the reference signal is used as a test signal to check the operability of the device and the presence of acoustic contact, as well as to set the rejection level.
• the rejection threshold is dynamically set equal to the difference between the current value of the amplitude of the reference signal and the proportionality coefficient K between the amplitudes of the reference signal and the echo from the RPM 13
• the coefficient K is found empirically when setting up the device.
• the technical means 11 for controlling and processing the measurement information concludes that the detected discontinuity is valid and continues to scan. Otherwise, the presence of an unacceptable DFD at the inspection site 1 is reported.
• the conditional size of the RPM 13 is judged, and knowing the travel time of the reference signal and the reflected wave, the spatial coordinates of this defect are calculated (Fig. 23).
• the choice of the echo-pulse method for ultrasound inspection in order to detect DFD is due to the high information content and ease of implementation of this method.
• the echo-pulse method requires free access to only one side of the inspection object, which is easier to provide in a production environment than access from two or more sides.
• the echo-pulse method makes it relatively easy to get rid of the reverberation noise from the coarse-grained structure of the object of inspection, as well as from interference due to reverberation from scale on the surface of the object of inspection, accompanying the operation of the device for ultrasonic inspection and interfering with the registration of signals from the SPD.
• the level of reverberation noise from the coarse-grained structure of the object of inspection, the presence of scale and surface irregularities are reduced.
• the decrease in the noise level from the reflected signals is caused by the attenuation of the signals as they pass through the inspection object. Since the re-reflected noise signal is always less intense than the useful echo signal, when passing the same path to the receiver, the re-reflected noise signal completely disappears and only the useful echo signal remains, attenuated, but having sufficient intensity to register it.
• the low level of reverberation noise from the coarse-grained structure is also caused by scanning of the object of inspection by ultrasonic waves of the Rayleigh type, which are surface waves, that is, sounding only the surface layer of the object of inspection, in which the desired RPM can occur, without sounding the inner and bottom parts of the object of inspection and without creating additional acoustic noise.
• the Rayleigh waves due to their propagation along the surface, made it possible to abandon continuous scanning point by point over the entire area of the inspection object, characteristic of the echo-pulse method in its classical version when ultrasonic vibrations are entered at an angle or normal to the surface of the inspection object, which ultimately improved inspection performance.
• Rayleigh surface waves also relieve the echo-pulse method of its inherent dead zone below the surface of the inspection object, where defects cannot be detected when ultrasonic vibrations are entered at an angle or along normal to the surface of the object of inspection, which makes it possible to inspect by echo-pulse method of RPD.
• the level of reverberation noise from the coarse-grained structure of the object of inspection is further reduced with respect to the useful echo signal due to dynamic calibration carried out relative to the reference signal, which helps to isolate the useful signal from the interference background by means of automatic amplification operating according to the level of the reference signal.
• Dynamic calibration also eliminates the dependence of the sensitivity of the inspection on the temperature of the inspected object and removes the limitation on the maximum surface temperature of the inspected object for inspection in terms of the necessary expansion of the dynamic range of reliable measurements.
• the use of a reference signal increases the reliability of the inspection.
• the limitation on the maximum surface temperature of the inspected object due to possible damage to the scanning unit is excluded due to scanning of the inspected object with an air gap between its surface and the EMAT working surface.
• the advantages of using EMAT should also include their undemanding quality of the surface of the objects of inspection.
• the productivity turns out to be maximum if the generator-receiver pair is placed from (2) - (5), providing the optimal geometry for solving the above problems.
• the reference signal as a test signal, it is possible to quickly detect the inoperability of the acoustic path or loss of acoustic contact and to avoid a drop in the performance of the inspection due to the need to re-check the objects of inspection.
• the absence of dependence on the location of the generator and receiver, for example, relative to the edge of the object of inspection allows you to change the direction of scanning without changing the position of the transducers, which ensures the efficiency of control and increases the productivity of the inspection.
• the control circuit according to which a probe pulse is generated that generates an ultrasonic wave propagating in the inspection object, is also simple and the receiver registers the radiation from the generator as a reference signal, and the radiation from the defect in the form of a reflected signal as a useful echo signal. Clocking is also characterized by simplicity, which simplifies the practical implementation of the method and device.
• the scanning unit in the best embodiment of the present invention has a structure (Figs. 24 and 25) containing a measuring module with two EMATs 7, 8, consisting of identical electric magnetizing coils 25 and a common U-shaped magnetic circuit 26, placed in the housing 27 on the base 28
• the scanning unit contains support rollers 29 of carbide and heat-resistant material to provide the necessary clearance between the object of inspection and EMAT.
• support rollers 29 carbide and heat-resistant material to provide the necessary clearance between the object of inspection and EMAT.
• carbide skis or compressed air inlets can be used to create an air cushion.
• the scan node is placed on the upper face of the inspection object 1 (Fig. 26) and is moved along its surface during the inspection.
• the scanning unit is supplemented with gripping rollers 30 (Figs. 27 and 28), which exclude arbitrary vertical displacement of the measuring module when scanning from the side of the side face of the inspection object 1.
• gripping rollers 30 Figs. 27 and 28
• Sufficiency for inspection of only two EMATs with one or two active elements made of identical electric magnetization coils 25 on a common magnetic circuit 26 ensures the simplicity of the design of the device for ultrasonic inspection.
• the most simple construction is characterized by a bi-directional EMAT with one active element, however, the signal from a unidirectional EMAT with two active elements exceeds the signal from a bi-directional EMAT by at least two times due to the interference of signals from two active elements, which increases the amplitude of the resulting signal, which is of particular importance to achieve high reliability and reliability of ultrasonic inspection during the inspection of objects with a coarse-grained metal structure.
• a unidirectional EMAT makes it relatively easy, unlike a bi-directional EMAT, to determine in which of two possible directions a defect was detected, which makes it possible to ensure simplicity of accurate localization of its position.
• support rollers 29 and gripping rollers 30 made it possible to implement means 5 for positioning and moving the transducers without a complicated mechanism for maintaining a constant air gap.
• this technical solution ensures the reliability and reliability of ultrasonic inspection of continuously cast billets, including slab and bloom, for the presence of real-time RPM in the flow of the production line and can eliminate the assumption of defective billets in the production of metal products.

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• 2016
  • 2016-01-15 WO PCT/RU2016/000005 patent/WO2017123112A1/ru active Application Filing
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