RU2248566C2 - Method for ultrasonic testing of cylindrical articles - Google Patents

Abstract

FIELD: non-destruction testing processes, possibly ultrasonic testing of cylindrical articles such as railway road wheels, bands, drums, pulleys and other products.

SUBSTANCE: method comprises steps of irradiating surface ultrasonic waves across cylindrical surface of article and receiving echo-signals caused by flaws; extracting signal passing around article n times; regulating amplification degree of received signals while sustaining constant amplitude of extracted signal; setting threshold levels for time intervals between probing signal and signal that passes around article one time, at time intervals between one time passing and two times passing signals, between two times and three times passing signals; evaluating flaw occurrence according to echo-signal exceeding threshold levels. Said threshold levels are set while taking into account features of distributing ultrasonic oscillations at their circulation in material of article. Number of n extracted signal is selected according to construction of cylindrical article and conditions of propagation of ultrasonic oscillation in it.

EFFECT: enhanced reliability and efficiency of testing articles.

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Description

The invention relates to the field of non-destructive testing and can be used for ultrasonic testing of cylindrical products, such as railway wheels, bandages, as well as drums, pulleys and other products.

In the national economy there is a large class of critical objects with cylindrical surfaces, subjected to ultrasonic testing both during manufacture and during periodic inspection.

Ultrasonic control of such products is mainly performed by installing a transducer (PEP) on the lateral cylindrical surface of the controlled object and performing circular scanning. Circular scanning is carried out either by moving the probe on the circumference of the end face or side surface of the product when the product is stationary, or when the probe is stationary by rotating the controlled product relative to its longitudinal axis [1, 2].

Ultrasonic testing of such products is very time-consuming and complicated. During the scanning process, the operator is required to sequentially review all the frames of the “A” scan [2] at each scanning point and, based on the change in the characteristic display (series of successive echo signals of different amplitudes) at individual scanning points, decide on the defectiveness of the controlled product. Naturally, such control has low reliability and low productivity.

Known methods of ultrasonic testing of cylindrical products based on the emission and reception of ultrasonic vibrations from the flat surface of the end or from the cylindrical side surface of the product and the analysis of the received echo signals.

So, for example, in the technical solution protected by US patent No. 4899590, in order to reduce the time for circular scanning and increase the performance of the control, an array of piezoelectric transducers is installed at the end of the controlled shaft. Such a technique does increase the control performance, however, the analysis of echo signals from various reflectors along the length of the monitored product (shaft) is still difficult and the reliability of the control remains low. In addition, controlling a system from a piezoelectric transducer array requires the use of rather sophisticated special flaw detection equipment, which generally makes the control process more expensive.

According to the technical solution, protected by author. testimonial. No. 1208209, long products (construction supports, shafts, axles, etc.) are controlled by analyzing the frequency spectrum of vibrations specially excited in the product by short-term strokes. This method of product quality control allows only approximately to estimate the presence of defects in the controlled product, requires laborious preliminary studies to compare the frequency spectra of natural vibrations of defective and defect-free products. In addition, the method has low reliability, since the desired parameter depends not only on the presence or absence of internal defects in the product, but also on the contamination of the external surface and other production reasons.

The method of ultrasonic testing of cylindrical products, protected by patent No. 2029300, is based on the registration of signals that repeatedly circulate the cylindrical surface along a generatrix, and measuring the amplitude or energy of the received oscillations in a certain time interval. The method allows to evaluate the quality of a certain zone (disk) of the product (layer-by-layer control), however, it is very time-consuming and has low reliability of control.

Known methods and devices for ultrasonic testing of cylindrical products protected by author. testimonial. No. 1408357, 1413517, 1415177, 1493945, 1486917, 1546901, 1566280, 1490625, 1515101, 1514252, as well as UK patent No. 866457 (CL H 4 D), providing for the emission of ultrasonic vibrations into the product, receiving a series of echo pulses from the product, scanning over the surface of the product by rotating the product or moving the probe and analyzing the echo signals displayed on the screen of the flaw detector (see, for example, [3]). The known methods have low performance and reliability, since they require the observation of echo signals of various amplitudes at a time scan proportional to the ultrasound path in the product at each transducer moving point.

A known method of ultrasonic testing of cylindrical products, allowing the registration of signals obtained during circular scanning on a scan of type B and thereby significantly increasing the performance and reliability of the control [4, 5]. However, this method is not effective when sounding products with pulses of surface waves from one (two) points of a cylindrical product.

A known method of ultrasonic control of cylindrical railway wheels, which consists in the fact that the controlled product is sounding with ultrasonic shear waves introduced from the side surface of the rim (band), register the echo signals and decide on the presence of discontinuities when registering an echo signal of sufficient amplitude [6] .

The disadvantages of this method are the low productivity of the control, due to the need to scan the entire product from the side surface, as well as the low reliability of the control, due to the inability to monitor the quality of the acoustic contact and, therefore, the sensitivity in the control process.

In the USA and Australia, attempts have been made to detect cracks by surface ultrasonic waves of a sufficiently low frequency (100-400 kHz) circling the rolling surface of a railway wheel [7, 8]. In experimental studies conducted in Germany, piezoelectric transducers were replaced by electrodynamic transducers built directly into the rail head (German patent No. 3218453) [9]. At the same time, it becomes possible to control the bandages of railway wheels directly during the movement of the rolling stock, without dismantling the wheels for diagnosis. However, the reliability of these control methods is insufficient, since the signals from dangerous internal (lying on the rolling surface 3 mm and deeper) defects are masked by signals from surface defects that are not dangerous for the operation of the wheels.

There is also known a method of ultrasonic control of wheels by surface waves running around a rim (bandage) along the rolling surface (US patent No. 3812708) [10]. The known method allows you to control the product by installing the Converter at one point on the surface of the surface and sounding by pulses of surface waves in the direction perpendicular to the generatrix, thereby significantly increasing the performance of the control.

The disadvantages of this method are the low sensitivity to subsurface defects, as well as low reliability due to the instability of the acoustic contact on the results of the control of the entire product.

Closest to the claimed technical solution and adopted for the prototype is the method (according to the patent of the Russian Federation No. 2032171 [11]) of ultrasonic inspection of cylindrical products, for example railway wheels, which consists in the fact that the product is heard by surface waves across its cylindrical surface and they are received and echoed signals from defects, measure the amplitude of the signal that has twice passed along the surface of the product, as well as the echo signal having the maximum amplitude, calculate the ratio of the measured amplitudes and the value obtained with DYT of defective products.

The advantage of the indicated technical solution is the compensation of the influence of the quality of the acoustic contact of the ultrasonic (ultrasonic) transducer with the product and the exclusion of the dependence of the control results on the parameters (amplitude) of the probe pulse emitted by the flaw detector.

Indeed, the quality of the acoustic contact and the magnitude of the amplitude of the probe pulses have a direct effect on the values of the amplitudes of the echo signals from potential defects and signals that run around the controlled product along its generatrix. At the same time, their ratio (the ratio of signal amplitudes) practically does not depend on these factors, but depends only on the magnitude of the echo reflected from the defect.

The disadvantages of the known method adopted for the prototype are:

1. Low control performance, due to the need to perform in the process of determining the defectiveness of the product sequential operations associated with:

1.1) the selection of the signal that has twice passed along the surface of the product, by measuring and storing its amplitude U ₀₂ ;

1.2) the allocation of echo signals from potential defects in time intervals (zones) between the probing and once running around, once and twice running around, twice and triple running around signals;

1.3) selection (determination) of all possible echo signals in the signal zones indicated in clause 1.2, having a maximum amplitude of U ^m ;

1.4) by measuring the amplitude U ^m determined in accordance with clause 1.3 of the echo signal and storing it;

1.5) by calculating the ratios K _{d of the} values of the two measured and stored in amplitudes of the signals (U ₀₂ and U ^m );

1.6) by comparing the magnitude of the ratio of amplitudes obtained in Section 1.5 with the value of K ₀ obtained previously on the basis of theoretical or experimental studies for this type of product.

2. The complexity of the automation of these operations, which means low reliability and control performance due to manual operations and the preservation of the subjectivity of the decision on the defectiveness of the product. When trying to automate control processes, significant computing power and unjustified hardware complications are required, which also reduces the reliability of the control.

3. The presence of unnecessary operations to extract and measure the amplitudes of the signals and calculate their amplitudes, which subsequently basically do not satisfy the specified criterion. For example, the sequences of operations 1.1-1.6 indicated in clause 1 must be performed for any appearance of echo signals in the specified time zones. In the practical control of a particular product (for example, wheels of railway wagons) on the surface of the product there are minor surface damage (dents on the wheel forming, traces of slipping, burrs on the edges of the wheels, etc.) that are not dangerous from the point of view of safety of its further operation. However, when controlling surface waves, these small damages cause the appearance of echo signals, which necessitates the measurement of their amplitudes by the operator (or the flaw detector processing device) and the subsequent calculation of the signal ratios U ^m and U ₀₂ with a further comparison of the obtained value with a threshold value. As a result, the operator spends considerable time on the control of each product or ignores the received signals, violating the established control technology and further reducing the reliability and reliability of the control of products.

Thus, the known method of ultrasonic testing of cylindrical products, adopted as a prototype, has low productivity, low reliability and reliability of control, complicates the automation of the process.

The technical problem solved by the claimed invention is to increase the reliability of ultrasonic testing of cylindrical products while simplifying the technology and increasing the performance of the control.

The problem is achieved in that the cylindrical product is heard by surface waves across its cylindrical surface, receive them and echo signals from defects, emit a signal that has passed n the surface of the product n times, further control the amplification of the received signals, maintaining the amplitude of the selected pass-through signal at a constant level, in the time intervals between the probing and once running around, once and twice running around, twice and three times running around through signals, I establish thresholds, and the defectiveness of the product is judged by the echoes exceed the established thresholds. Moreover, the threshold levels in time intervals between probing and once running around, once and twice running around, twice and triple running around through signals are set taking into account the propagation of ultrasonic vibrations during circulation in the product material, and the number n of the selected through signal is selected based on the design features of the cylindrical product and propagation conditions of ultrasonic vibrations in it.

The ultrasonic method for controlling cylindrical products, considered further on the example of the bandage (rim) control of the wheels of railway rolling units (cars, locomotives, car trips, etc.), is based on the use of an echo-pulse method of ultrasonic control by surface waves. In this case, the properties of cylindrical waves are used to circulate along the cylindrical surface, partially reflecting from inhomogeneities in the surface layer, forming echo signals, and partially passing them, forming a series of gradually decaying through signals that have passed (circled) the product 1, 2, 3 or more times. Obviously, the time intervals between the through signals are constant, determined by the diameter of the controlled cylindrical product and the speed of propagation of ultrasonic vibrations in the material of the product.

With the surface sounding of a cylindrical product perpendicular to the generator in the intervals between circulation pulses (through pulses), a sequence of echo signals from one defect is formed, in which the second and subsequent echo signals are caused by the interaction of pulses reflected from the defect and passed the defect on the way to the receiving electro-acoustic transducer.

When implementing the method on a bandage (rim) of the wheel, a fixedly inclined electro-acoustic transducer is installed, operating in separate or combined mode. Sounding is performed by pulses of surface waves in the direction perpendicular to the generatrix of the cylindrical surface, and signals are circulated that circled the product (through - circulating) and, in the presence of defects, also echo signals from them. Through temporary gating, there are isolated through signals that run around the product n times, where depending on the diameter of the controlled product and on the degree of attenuation of ultrasonic vibrations n = 1, 2, 3, 4 ... for the considered example of control of railway wheels, as practice shows, it is advisable to select the second (n = 2) pass-through signal. By adjusting the overall gain of the receiving path of the flaw detector, the second end-to-end signal is maintained at a constant reference level. In the time intervals between the pass-through signals, a certain amplitude threshold level is set.

If the amplitude of the echo signals of a given threshold is exceeded, a decision is made about the defectiveness of the controlled product. Moreover, the threshold levels in the time intervals between the probing and once running around, once and twice running around, double and triple running around signals due to the propagation of ultrasonic vibrations during circulation in the product material, in general, can differ from each other.

It should be noted that in the considered example of the implementation of the proposed method, the choice as a reference signal, twice (n = 2) running around the wheel rim (second through) signal, due to the design features (diameter, geometric dimensions and material) of the controlled product. Obviously, for other cylindrical products with different structural parameters, the most informative (reference) signal that runs around the product will be not the second, but the first (with large diameters), third, fourth (with smaller diameters) or (n-th) through signal . Therefore, for a particular product, the choice of a reference signal that most clearly responds to changes in the parameters of emitted pulses and changes in the quality of acoustic contact should be based on theoretical or experimental studies.

The main operations that distinguish the proposed method from the prototype are to maintain the amplitude of the nth (for the considered example n = 2) pass-through signal at a constant level by adjusting the overall gain of the received signals and setting amplitude thresholds between individual pairs of pass-through signals (at the same or different levels ) The implementation of this sequence of basic operations of the method can be carried out manually by the operator or in semi-automatic mode using circuitry solutions incorporated into the flaw detector [12].

The latter option is preferable and can be implemented, for example, on discrete elements (known gate-pulse generators, triggers, automatic gain control circuit (AGC), amplifier, attenuator, and defect detector on transistors and microcircuits) [13, 14]. At the same time, maintaining the selected pass-through signal at a constant level is performed automatically using the automatic gain control (AGC) system built into the flaw detector.

It should be borne in mind that automatic gain control in pulse signal receivers, which are the receiving paths of ultrasonic flaw detectors, is distinguished by some features. Echo and end-to-end signals at the input of the detector detector exist for a relatively short time, depending both on the duration of the pulses and on their duty cycle, determined by the frequency of sending probe pulses. In this regard, the response time of the automatic gain control system (AGC) and the rate of regulation of the gain of the receiver begin to noticeably affect the operation of the receiving path.

Therefore, when implementing the proposed method in a flaw detector, it is necessary to use high-speed pulse (BARS) AGC systems or the so-called instantaneous AGCs (MARU), for example, assembled according to the MARU scheme with a shunt diode (see Fig. 13.30, p. 407 [15]).

In modern ultrasonic flaw detectors (flaw detectors with digital signal processing), nodes that ensure the execution of the sequences of operations of the proposed method are implemented on a programmable logic integrated circuit (FPGA), which operates under the control of an integrated microprocessor [16]. In particular, in the general-purpose ultrasonic flaw detector Peleng UD2-102 manufactured by ALTEK CJSC (St. Petersburg), the sequence of actions provided for by the method is performed automatically using a high-speed AGC [17]. With AGC, the level of the second pass-through signal is kept constant. In this case, the overall gain of the entire receiving path of the flaw detector is accordingly regulated, which leads to compensation for the influence of destabilizing factors (changes in the quality of the acoustic contact of the ultrasonic transducer with the product and the exclusion of the dependence of the monitoring results on the parameters of the probe pulse emitted by the flaw detector).

In order to avoid narrowing the subject of the invention, the application materials do not provide a specific implementation scheme of the proposed control method (manual or automatic using an analog or digital flaw detector with AGC). Regardless of the implementation method, when implementing the proposed method, it is necessary to carry out the above sequence of actions:

- sounding of the product by surface waves across its cylindrical surface;

- reception of end-to-end signals and echo signals from possible defects;

- adjustment of the gain of the received signals, maintaining the amplitude (level) of one of the selected end-to-end signals at a constant (reference) level;

- setting threshold levels in time intervals between the probe and the first run around the product, the first and second and second and third and other pairs of pulses;

- making a decision on the defectiveness of the product by echo signals that exceeded the threshold level.

As can be seen from the comparative analysis of the sequential actions performed during the implementation of the proposed method and the method adopted as a prototype, when controlling cylindrical actions, it is no longer necessary to measure and remember the amplitudes of the signal U ₀₂ and the echo signal having the maximum amplitude U ^{m that} twice passed along the surface of the product . There is also no need to calculate their cd ratio. These time-consuming actions are replaced by automatic regulation of the sensitivity of the flaw detector receiving path according to the level of the second end-to-end signal and fixing the appearance of an echo signal above the established threshold levels in time intervals between the probing and once obzhivshim, once and twice obzhivshim, twice and three times obzhevshim signals.

The choice of amplitude thresholds in each time interval between pairs of through signals is carried out previously on the basis of theoretical or experimental studies for a specific type of control objects. Moreover, the thresholds in each specified time interval can be not only linear (constant throughout the time interval), but also vary according to a certain law (a variable level in time). For example, for solid-rolled wheels of railway passenger cars, an exponentially decaying law of a change in the threshold value level is characteristic, depending on the path traveled during the circulation through the product by ultrasonic waves.

Thus, the technical problem posed by the development of a method for ultrasonic testing of cylindrical products is completely solved. The introduction of gain control of the received signals, maintaining the amplitude of the extracted pass-through signal at a constant level, allows you to compensate for possible fluctuations in the quality of the acoustic contact and the amplitudes of the probe pulses, while maintaining a constant control sensitivity. Setting threshold levels in time intervals between pairs of pass-through signals, taking into account the propagation of ultrasonic vibrations in the product, allows more reliable detection of dangerous defects in cylindrical products without performing additional operations to extract signals with a maximum amplitude and measure the ratio of the amplitudes of the echo signal and the selected pass-through signal. The exclusion of these additional operations increases the reliability and performance of the control.

The introduction of a flaw detector at the enterprises of the Ministry of Railways of Russia made it possible to significantly increase the reliability and performance of ultrasonic inspection of bandages of solid-rolled wheels of passenger cars, thereby helping to improve the safety of train traffic [18].

Sources of information

1. Instructions for ultrasonic flaw detection of shafts of the main drive of subway escalators. Ts Metro / 4278. Approved General Directorate of Metro 06/13/86. M .: Transport, 1987.

2. Methods of acoustic control of metals. / Ed. N.P. Aleshin. - M.: Mechanical Engineering, 1989 .-- 456 p.

3. Pantyushin A.I. and other Device for ultrasonic testing of tubular products. Auth. testimonial. No. 1415177, Bull. fig. No. 29, 1988.

4. Harutyunyan Yu.K., Babichev V.A. et al. Method for ultrasonic testing of cylindrical products. Patent for invention No. 2149393, 2000.

5. Markov A.A. Alternative presentation of defectoscopic information in portable ultrasonic flaw detectors. - In the world of non-destructive testing. No. 1 (7), 2000 S. 42-44.

6. Flaw detection of parts of rolling stock of railways and subways. / Ed. V.A. Ilyina. M .: Transport, 1984, pp. 40-45.

7. Bray D.E. Dalvi N.G. Finch R.D. Ultrasonic flaw detection in model railway wheels. Ultrasonics 11 (1973) 66-72.

8. Kemeny LG Automated nondestructive testing techniques for computerized inspection of wheels in motion. Proc. 9 ^th World Conf. NDT Melbourne 1979.Rep. 1C-1.

9. Salzburger H J. Repplinger W ... Anordnung und Schaltung zur zerstorungsfreien Prufung der Laufflache von Eisenbahnredern. DE Pat. 3218453 (1983).

10. US patent No. 3812708, G 01 N 29/10, 1976.

11. Dymkin G.Ya., Gurvich A.K., Kostyuk O.M. The method of ultrasonic testing of cylindrical products. Patent for invention No. 2032171. Bull. fig. No. 9, 1995.

12. Ilyin V.A., Batuner A.P., Kasparova A.T. and others. New non-destructive testing devices (UD-11PU, UD 2-12, DI-4 flaw detectors). M .: Transport, 1990.

13. Design of radar receiving devices: Textbook. allowance for radio technology. specialist. universities./ Ed. A.M. Sokolova. - M .: Higher. School, 1984. - 335 p.

14. Goroshkov B.I. Elements of electronic devices: Reference. - M :. Radio and communications, 1989 .-- 176 p.

15. Barkan V.F., Zhdanov V.K. Radio receivers - M .: Owls. Radio, 1978.- 464 p.

16. Kretov E.F. Ultrasonic flaw detectors in the Russian market. / In the world of non-destructive testing, No. 2, 1998, p.6-8.

17. Ultrasonic flaw detector "PELENG" UD2-102. Manual. CJSC Altek. St. Petersburg, 2001.

18. Instructions for ultrasonic testing of solid-rolled wheels of cars with the programmable flaw detector "PELENG" UD2-102. M .: VNIIZHT, 2000. - Approved. Departments of carriage facilities and passenger communications of the Ministry of Railways of Russia.

Claims (3)

1. The ultrasonic method for monitoring cylindrical products, which consists in the fact that the product is emitted by surface waves across its cylindrical surface and receives them and echoes from defects, they emit a through signal that has run around the product n times, characterized in that they control the gain of the received signals, supporting the amplitude of the selected end-to-end signal at a constant level, in time intervals between the probing and once running, once and twice running, twice and three times running through E signals set thresholds, and the defectiveness of the product is judged by the echo signals exceeds the preset thresholds. 2. The ultrasonic method for monitoring cylindrical products according to claim 1, characterized in that the threshold levels in time intervals between the probing and once running, once and twice running, running twice and triple running through signals are set taking into account the propagation of ultrasonic vibrations during circulation in the material of the product . 3. The ultrasonic method for monitoring cylindrical products according to claim 1, characterized in that the number n of the selected end-to-end signal is selected based on the design features of the cylindrical product and the propagation conditions of ultrasonic vibrations in the product.