RU2137120C1 - Method of ultrasonic inspection and gear for its realization - Google Patents

Abstract

FIELD: study of materials with use of ultrasonic waves, detection of flaws in solids. SUBSTANCE: invention makes it feasible to conduct inspection with automatic decoding of measurement results that can authentically determine coordinates of flaw, its height, type and extent thanks to discreteness of measurement processing. Units of acoustic converters are placed on both sides of inspected weld, are moved along weld, entire section of weld is insonified with ultrasonic waves, these waves are received and signals are processed to detect flaws. Discreteness of processing of received signals is set by signal from path-control transducer. Inspection of acoustic contact is conducted at each step of processing, normalization of amplitudes of signals received from flaws with reference to level of corresponding signals of acoustic contact is carried out. By measured amplitudes there are determined height and type of flaw in agreement with given algorithm, path covered and coordinates of flaw. Gear for realization of method has cases which carry units of acoustic converters, aids for translation of cases along weld and flaw detector electrically connected to units of acoustic converters. Gear is fitted with path-control transducer and indicator of acoustic contact. Flaw detector has microprocessor connected to storage, control unit and interface for connection with external devices to which inputs path-control transducer and keyboard are linked and to which outputs former of gate pulse, screen and indicator of acoustic contact are connected. EFFECT: authentic detection of coordinates of flaw, its height, type and extent. 5 cl, 6 dwg

Description

 The invention relates to the study of materials using ultrasonic waves and is intended to detect defects (discontinuities) in solids, in particular for quality control of welds.

 Known methods and devices for ultrasonic testing (application GB, 2292610, class G 01 N 29/16, 1996; application PCT, WO 94/19686, class G 01 N 29/04; patent US, 5511425, class G 01 N 29/04, 1996; French patent N 2594550, CL G 01 N 29/04, publ. 1987).

 A known method (French patent N 2594550, class G 01 N 29/04, 1987), which includes installing blocks of acoustic transducers from different sides from a controlled weld, moving them along the seam, irradiating ultrasonic waves throughout the weld zone, receiving Ultrasound waves, automatic processing of received signals and receiving at each stage a direct image of the defect. A device that implements the specified method contains a housing, in each of which a block of acoustic transducers is installed. The acoustic transducer blocks are connected to a processing system associated with a visualization system. Processing system and visualization system - flaw detector. The bodies are equipped with means for moving them along the weld.

 The disadvantages of the known method and device is the inaccuracy of control, due to the introduction in the measurement of errors associated with the violation of acoustic contact, the lack of determination of the type of defect. In addition, products of only one thickness are monitored, as acoustic blocks are rigidly fixed relative to each other.

 The objective of the proposed solution is to create a control method and device with automatic decoding of measurement results that can reliably determine the coordinates of the defect, its height, type and extent due to the discreteness of the measurement processing specified by the path sensor, and the adjustment of sensitivity at each processing step in accordance with the level of acoustic contact. In addition, one of the tasks is to create a device for the control of welded joints (butt, lap), which allows you to rebuild the device during control from one thickness to another.

 The problem is achieved in that in the method of ultrasonic testing, which includes installing blocks of acoustic transducers on both sides of the controlled welded joint, moving them along the welded joint, sounding by ultrasonic waves the entire cross section of the welded joint, receiving ultrasonic waves and processing signals to detect defects , the processing resolution of the received signals is set by the signal from the path sensor, and at each processing step, the acoustic contact, and carry out the normalization of the received amplitudes of the signals from the defect relative to the level of the corresponding signals of the acoustic contact, the measured amplitudes determine the height and type of defect in accordance with a given algorithm, measure the distance traveled and determine the coordinates of the defect. Acoustic contact control is carried out by re-emitting ultrasonic waves to a controlled object from one transducer to another inside each acoustic unit.

 In the device, the task is achieved in that it contains cases on which the acoustic transducer blocks are mounted, means for moving the bodies along the controlled connection, and a flaw detector electrically connected to the acoustic transducer blocks is additionally equipped with a sensor for measuring the distance traveled and an indicator of the presence of acoustic contact, and the flaw detector contains a microprocessor connected to a memory node, a control node and a node for interfacing with external devices and to the inputs of which the sensor for measuring the distance traveled, a keyboard are connected, and a strobe forming unit, a screen and an indicator of the presence of acoustic contact are connected to the outputs, the strobe forming unit through the serially connected control unit and the excitation and amplification unit connected to the acoustic units.

 The ability to control products of different thicknesses is achieved by the fact that the housings are interconnected with the possibility of changing the distance between them and fixing them in different positions, the acoustic transducer blocks are spring-loaded relative to the housings, and on one of the housings there is a spring-loaded sensor for measuring the distance traveled, electrically connected to the flaw detector, while the blocks of ultrasonic piezoelectric transducers are installed in housings with the possibility of removal.

 When implementing these decisions, the reliability and efficiency of control is increased, and information is also displayed in a form convenient for the operator. In addition, the range of controlled compounds is expanding.

 In FIG. 1 shows a functional diagram of a device that implements the inventive method; in FIG. 2 - a device for ultrasonic testing implementing the proposed method; in FIG. 3 - flaw detector operation algorithm in control mode; in FIG. 4 is a kinematic diagram of a device that implements the inventive method; in FIG. 5 is a section A-A in FIG. 4; in FIG. 6 is a functional diagram of a microprocessor.

 A device for implementing the method comprises (Fig. 1) blocks 1 and 2 of acoustic transducers connected to a flaw detector 3, a sensor 4 for measuring the distance traveled, and an indicator 5 for acoustic contact. The flaw detector 3 contains a microprocessor 6 connected to the inputs and outputs of the memory unit 7, the control unit 8, and the interface unit 9 with external devices, and the inputs are connected to the outputs of the measured path sensor 4 and the keyboard 10, and the outputs are connected to the inputs of the gate forming unit 11 pulses, the screen 12 and the indicator 5 of the presence of acoustic contact, and the node 11 of the formation of strobe pulses through serially connected node 8 of the control unit 13 of excitation and amplification is connected to the acoustic transducers 14 ... 21 of blocks 1 and 2 (Fig. 2). Blocks 1 and 2 are a multi-element speaker system, for example, as in FIG. 2. They contain 6 ... 16 pieces of piezoelectric transducers installed in the corresponding frame of a closed profile, designed to emit ultrasonic waves with a frequency of 2.5 ... 5 MHz into the product by contact and to receive reflected and transformed waves from defects (cracks, lack of penetration, slag inclusions , then, etc.) welded joint. The thickness range during the control of one set of blocks is up to 25 mm.

 As control elements, various types of acoustic blocks can be used, differing among themselves in the different arrangement of the probe in the blocks, and thereby various well-known control schemes and techniques are implemented, such as echo, echo-mirror, mirror-shadow; combined, separately-combined ("tandem", "delta") control schemes, which, along with the use of probes with wide radiation patterns and with large input angles, makes it possible to identify defects of all types throughout the welded joint section.

 Blocks 1 and 2 (Fig. 4) are installed respectively in the housings 22 and 23, which are equipped with a means of movement 24 made in the form of bearings mounted on the end walls of the housings and moving blocks 1 and 2. The housings 22 and 23 are connected, for example, to each other with the ability to change the distance between them, for example, according to the type of telescopic connection, for quick adjustment of the device to control a different thickness and are equipped with an adjusting and fixing mechanism 25.

 The blocks of ultrasonic piezoelectric transducers (PES) 1 and 2 are spring-loaded with a spring 26 relative to the corresponding housing. Block 1 is installed on the housing 22, and block 2 on the housing 23 using the suspension 27. The sensor for measuring the distance traveled 4 is mounted on one of the buildings, for example, 22. The acoustic contact indicator 5 is mounted on the outer surface of the housing 22 (Fig. 2).

 Cases 22 and 23 are made according to the type of box-section construction (Fig. 4).

 The adjusting and fixing mechanism 25, containing a spring-loaded ball mounted on the housing 23 and located between the housings 22 and 23, provides a fixation of the relative position of the housings by fixing the ball in the recesses made in the calculated places of the housing 22. The suspension 27 includes springs 26 and fixing screws 28 (Fig. 5). Using screws 28, block 1 is fixed to the suspension 27, which in turn is connected to the housing 22 by means of springs 26. The attachment unit of block 2 is similarly designed. The spring clamp 26 provides reliable acoustic contact between the probes 1 and 2 with the controlled surface.

 The type of connection of the enclosures described in the invention, the implementation of the adjusting and fixing mechanism 25 and the installation unit — the suspension unit 27 of the acoustic transducer blocks are some examples of their implementation that illustrate the invention but do not limit its scope.

 The microprocessor 6 (Fig. 6) includes an input device 29, an input-output device 30, an analog-to-digital converter 31, an arithmetic logic device 32, a register device 33, a controller 34, and an output device 35 that are connected to a common bus 36. To the inputs of the input device 29 are connected a path sensor 4 and a keyboard 10. The input / output device 30 is connected to the node 9 of the interface with external devices. The output of the control unit 8 is connected to the analog-to-digital converter 31. The controller 34 is connected to the memory unit 7. The output device 35 is connected to the inputs of the indicator 5 of the presence of acoustic contact, the control unit 8, the gate-forming unit 11 and the screen 12.

 The proposed method is as follows.

 The blocks 1 and 2 of the acoustic transducers (Fig. 2) are installed on both sides of the controlled welded joint and then move them along the seam.

 When blocks 1 and 2 move with a signal from the sensor 4, the paths determine the discreteness of information processing, i.e. pulses from the sensor 4 paths enter the flaw detector 3, which includes the transducers. The resolution of information processing or the processing step is chosen arbitrarily, for example, 1 mm.

 Each millimeter of the controlled compound is voiced by the number of K cycles. In each step, a certain control scheme is implemented, i.e. ultrasound signals are emitted by a certain probe from a probe and ultrasonic signals are received by a certain probe (Fig. 2), for example, 17 and 21. The location of the signal from the defect is determined experimentally and in the zone of the appearance of this signal, a strobe pulse of a certain duration is set, and the signal amplitude value depends on the magnitude of this defect, by exceeding the signal amplitude of certain threshold values, the height of the defect is determined.

 At the end of the last measure, i.e. at the end of one measurement cycle, the measurement values are saved. The number of cycles until the next pulse from the path sensor 4 is determined by the speed of movement of the acoustic blocks 1 and 2, the duration of the beat and their number, i.e. on each millimeter of the path N cycles of measurements occur, each of which consists of K clock cycles. On each "mm" path, automatic monitoring of the level of acoustic contact in the probe blocks is carried out by alternately emitting ultrasonic waves into the metal of one probe, for example 17 (Fig. 2), and receiving these waves and measuring the signal amplitude by another probe, for example 14 (Fig. 2), according to the mirror-shadow control scheme inside each block. In the case of a change in the sensitivity level, for example, due to a change in roughness in the heat-affected zone on the working or bottom surfaces of the product, the amplitude of the acoustic contact signal will also change. When measuring the amplitudes of signals from defects, sensitivity is adjusted by normalizing the amplitudes of signals from defects relative to the level of the corresponding acoustic contact signals. Then, according to the amplitudes of the received signals, the average values of the height of the defects are determined, according to a certain combination of signals in ticks, the type of defect is determined according to the algorithm for determining the type of defect. Remember the defect parameters. Summing the pulses from the path sensor 4, determine the total length of the inspected portion of the welded joint and the coordinates of the defects (Fig. 3).

 A device that implements the proposed method works as follows.

 Before starting the control, the surfaces of the welded joints are prepared for work: they are cleaned and covered with a uniform layer of contact liquid, for example, transformer oil.

 Based on the specified thickness of the controlled welded joint and the corresponding width of the reinforcement roller, the housings 22 and 23 are pushed apart, fixing them at a certain distance, while the position of the housings is fixed using the adjusting and fixing mechanism 25. After that, select the necessary probe blocks 1, 2 and fix them on the appropriate housing using screws 28 to the suspensions 27.

 Connect the cable from the flaw detector 3 (not shown) to the probes, fix the connection with the appropriate connectors, turn on the flaw detector 3 and set the thickness of the product, the number of the acoustic unit using the flaw detector keypad 10, other traditional flaw detector settings are not required.

 The device is installed on a controlled welded joint, the heat-affected zone of which is prepared for testing. The movement is carried out manually, with a speed of not more than 1 m / min, which is provided by the movement mechanism 24. During control, stops and a smooth increase in speed within 1 m / min, as well as adjustment of the position of blocks 1 and 2 relative to the axis of the welded joint are possible. When moving the device, the sounding of the entire cross section of the welded joint is performed. Acoustic contact, in the case of crossing an obstacle, is ensured by pressing the probe blocks with a spring 26 and the presence of a lubricant layer on the surface of the welded joints.

 From the moment of movement of the acoustic blocks 1 and 2, the path sensor 4 (Fig. 1.4), which is the reference marker with a pitch of, for example, 1 mm, sends a pulse to the microprocessor 6, namely through the input device 29 to the register 33 device, which software downloads the control parameters through the output device 35 to the control unit 8 (Fig. 1) - threshold values of the amplitude of the signals in each cycle, the numbers of amplifiers, generators included in a particular cycle, and sets the gain in each cycle, and in the node forming the strobe impulses 11 sets the beginning of the gates and their duration, after which all the strobe pulses are placed in the control unit 8.

 In each cycle, the control unit 8 according to a certain algorithm sends signals to the excitation and amplification unit 13, which in a certain sequence includes amplifiers and generators (not shown). For example, in the first cycle, probes 16 and 20 work, probes 16 emit ultrasonic waves and receive, and probes 20 only receive. All signals that are fed to amplifiers operating in the first cycle with probes 16 and 20 are sent to control unit 8. If the received signals fall into the strobe pulses corresponding to the first cycle, then the amplitudes of these signals are fed to the analog-to-digital converter 31 of the microprocessor 6, where these signals are processed by arithmetic logic 32 and register 33 of the device according to the program, and then the measurements are temporarily sent through the controller 34 to the memory unit 7. In the second clock cycle, for example, probes 19 and 15 work, the signals falling into the strobe pulses corresponding to the second clock pulse are likewise sent to the analog-to-digital converter 31 of the microprocessor 6, and then after processing to the memory unit 7. The probes work in the same way in other measures. The last two measures are connected with the acoustic contact signal. PEP 21 of block 1 sends an ultrasonic wave, and PEP 18 receives it, the amplitude value of this signal is sent to microprocessor 6. Similarly for block 2, PEP 17 sends, and PEP 14 receives an acoustic contact signal, the value of which is also sent to microprocessor 6. Next, microprocessor 6 in the arithmetic-logic device 32, all incoming signals are normalized relative to the acoustic contact signals, i.e., if the acoustic contact signals are less than normal, for example, by 4 dB, then all other signal amplitudes are increased by 4 dB. If the signal of the acoustic contact differs from the norm by no more than, for example, 12 dB, then through the output device 35, a signal is supplied to turn on the indicator 5 of the presence of the acoustic contact. If the acoustic contact signal differs by more than, for example, 12 dB from the norm, then it is considered that the acoustic contact is broken, and the acoustic contact presence indicator 5 is not turned on, and a message about the violation of the acoustic contact after the end of the control is displayed and printed.

 At the end of the last measure, i.e. at the end of the measurement cycle, the values of all amplitudes are processed in the arithmetic-logical 32 device of the microprocessor 6 and the processing results are sent to the memory node 7, where they are temporarily stored. The number of cycles until the next impulse from the path sensor 4 is determined by the speed of movement of blocks 1 and 2, the duration of the beat and their number, i.e. on each millimeter of the path N cycles of measurements occur.

 When the next pulse from the path sensor 4 arithmetic-logical 32 device through the controller 34 calls all the time measurements from the memory node 7, summarizes the measurements of the cycles, determines the average value of the defect height, determines the type of defect from a certain combination of signals in clocks, according to the algorithm for determining the type of defect , and records the parameters: type of defect (plane or volumetric or volumetric-plane), the height of the defect in the memory node 7. Next, the microprocessor 6, reading the pulses from the path sensor 4 and summing them, determines it is the total length of the monitored section of the welded joint; when signals appear in ticks, the microprocessor 6 processes them, writes them to the memory node 7, which makes it possible, after the end of the control, to determine the coordinate of the onset of the defect, its height, type and length. The inspection results are viewed on the screen 12 of the flaw detector 3 and the operator, based on the results of the inspection, decides on the quality of the welded joint, and by connecting the printer to the flaw detector 3, prints the results by pressing the corresponding buttons on the keyboard 10.

 If necessary, the device of ultrasonic quality control of welded joints can be connected to a computer for additional input of control parameters and change of operating algorithms using the interface node with external devices 9.

Claims (5)

 1. The method of ultrasonic testing, which includes installing blocks of acoustic transducers on both sides of the controlled welded joint, moving them along the welded joint, sounding ultrasonic waves of the entire cross section of the welded joint, and ultrasonic waves and signal processing to detect defects, characterized in that the processing resolution of the received signals is set by the signal from the path sensor, and at each processing step, the acoustic contact is monitored and They determine the normalization of the received amplitudes of the signals from the defect relative to the level of the corresponding acoustic contact signals, determine the size and type of the defect in accordance with the specified algorithm from the measured amplitudes, measure the distance traveled and determine the coordinates of the defect.  2. The method according to p. 1, characterized in that the control of the acoustic contact is carried out by re-emission of ultrasonic waves into the controlled object from one ultrasonic transducer to another inside each acoustic unit.  3. Device for ultrasonic testing, comprising housings on which the acoustic transducer blocks are mounted, means for moving the housings along the controlled connection and a flaw detector electrically connected to the acoustic transducer blocks, characterized in that it is additionally equipped with a sensor for measuring the distance traveled and an indicator of the presence of acoustic contact and the flaw detector contains a microprocessor connected to the inputs and outputs of the memory node, the control node and the interface node with external devices with devices and inputs connected to the outputs of the sensor measuring the distance traveled and the keyboard, and outputs to the inputs of the strobe shaping unit, the screen and the indicator of the presence of acoustic contact, the strobe forming unit is connected to the second input of the control unit, which is through the excitation and amplification unit connected to acoustic units.  4. The device according to p. 3, characterized in that the cases are equipped with a spring-loaded sensor for measuring the distance traveled and an indicator of the presence of acoustic contact, the cases are interconnected with the possibility of changing the distance between them and fixing them in different positions, and the blocks of acoustic transducers are spring-loaded relative to the cases .  5. The device according to paragraphs. 3 and 4, characterized in that the blocks of ultrasonic piezoelectric transducers are installed in housings with the possibility of removal.

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