RU2589486C2 - Method to detect and control defects of products from metal - Google Patents

Abstract

FIELD: testing equipment.

SUBSTANCE: metal item is scanned with a probing signal, generated by a transmission device, and a signal arising in a defect metal item is received with the help of a receiving device, at the same time the probing signal is generated in the form of the 1st harmonic of the signal, and as the one reflected from the metal item, they receive the 3rd harmonic of this signal arising in the defect.

EFFECT: increased reliability of defect detection.

3 cl, 5 dwg

Description

The invention relates to measuring equipment, namely to monitoring the condition of metal products and can be used in various branches of engineering and instrumentation, in particular, and the Russian railways (JSC Russian Railways) in the study of the side frames (BR) of freight carriages.

The most common method for detecting CR cracks is visual inspection.

The disadvantages of this method is the omission of cracks due to:

- cracks in invisible areas for inspection;

- Features of the adaptation of a person’s vision when translating a view from light to shadow and back, which is several minutes. Repeated dark and light eye re-adaptation significantly reduces the visual acuity of examiners;

- the absence in the arsenal of inspectors of technical means of remote objective control of the integrity of the BR.

The ultrasonic, flux-gate, and acoustic-emission methods of defectoscopy widely used at the Russian Railways JSC are laborious and expensive, require thorough cleaning of the surface of the examined frame from various contaminants (ice, dirt, oil products ...) to ensure high-quality contact with sensors and equipment and are most suitable ( taking into account the requirements for user qualifications) for use in stationary conditions. The acoustic “intelligent hammer” being tested by the Clean Technologies company (St. Petersburg) has the same drawback.

As a prototype, a method and device for identifying objects, active radio wave detection and non-destructive testing of natural, industrial and operational defects and inclusions of systems and objects of natural and technogenic nature, described in the application RU 2006103112, where an electromagnetic field is excited in a controlled product by external electromagnetic radiation, is adopted radiated electromagnetic signals, measure their parameters and determine the presence of defects according to the measurement results.

However, in this technical solution, the received electromagnetic signals are created due to the occurrence of macrocurrents and bias currents characteristic of capacitive elements, for which the controlled product is irradiated using metal plates and shells through dielectric plates and shells that play the role of a kind of capacitor system between which establish a controlled product, and these plates are laid out in a certain way along the contour of the test product, As a result, the field emitted by the product, and hence the spectral characteristics, becomes object-oriented, that is, the product itself becomes an antenna and begins to emit electromagnetic waves, the spectrum of which identifies the object of study, which is complex, not accurate enough and limited in application .

The problem to which the invention is directed, is to increase the safety of operation of metal products that have various defects during operation, in particular cracks.

The task is achieved using the technical result obtained from the use of the invention, which consists in increasing the accuracy and reliability of the integrity control of metal objects by creating a method for remote non-destructive testing of cracks that occur in areas invisible to inspection, and creating a device that implements this method.

The problem is achieved in that the surface of the metal product is scanned by a probe signal forming a transmitting device, and the signal converted by the nonlinearities of this metal product is received using a receiving device. In this case, the probe signal is formed in the form of the 1st harmonic of the signal, and the 3rd harmonic of this signal arising in the defect is taken as the metal product transformed by contact inhomogeneities.

To increase the signal-to-noise ratio, together with the probing signal, the metal product is subjected to simultaneous mechanical action (shock, vibration, etc.) or the amplitude-modulated 1st harmonic of the probe signal is used as the acting signal on the metal product.

This method can be implemented using the devices shown in FIG. 1, 2, 3, where:

1 - master oscillator

2 - Frequency Doubler

3 - Sound signal amplifier

4 - Harmonic Filter

5 - Antenna of the probing signal

6 - Receiver Antenna

7 - Input filter

8 - Input Amplifier

9 - Synchronous phase detector

10 - Frequency triple

11 - Adjustable local oscillator voltage phase shifter

12 - Filter and amplifier output signal SFD

13 - Processing device

14 - Receiver indicator

15 - Low-frequency generator

16 - Low Frequency Power Amplifier

17 - Source of mechanical stress

18 - Amplitude modulator

19 - Modulating generator.

In FIG. 1 shows a device in which: a transmitting device is a generator of the 1st harmonic of a probe signal (ZS), and a receiving device is a device for receiving the 3rd harmonic of a ZS. In the device, the AP generator is built according to the classical scheme and contains a serially connected master oscillator 1, a frequency doubler 2, an amplifier of the probing signal 3, a harmonics filter 4 and an antenna of the probing signal 5. Receiving - a device for receiving the 3rd harmonic of the AP, consists of a receiver antenna 6, the output of which through the input filter 7 and the input signal amplifier 8 is connected to one of the inputs of the synchronous phase detector (SFD) 9, which must have two nonlinear elements inside which are connected in parallel. Another input SFD 9 is supplied with voltage from the master oscillator 1 through a frequency tripler 10 and an adjustable phase shifter 11, and the output SFD 9 is connected through a filter and amplifier 12 of the output signal SFD to the processing device 13 and indicator 14.

In FIG. 2 shows the transmitting and receiving device shown in FIG. 1, in which the output of the low-frequency generator 15 is connected to the processing device 13 (Fig. 1), the output of which is also connected to a low-frequency power amplifier 16, the output of which is connected to the source of mechanical impact 17.

In FIG. 3 shows the transmitting and receiving device shown in FIG. 1, where an amplitude modulator 18 is connected between the frequency doubler 2 and the probe signal amplifier 3, the second input of which is connected to the output of the modulating generator 19, and the output of the modulating generator 19 is connected to the processing unit 13.

A device for detecting and controlling defects in metal products works as follows.

The voltage from the master oscillator 1 is supplied to the frequency doubler 2 and the frequency of the 1st harmonic of the probe signal (ZS) is obtained, which is amplified by the amplifier 3, filtered by the harmonics filter 4, radiated to the diagnostic object using the transmitter antenna 5. The emitted signal is passed through the harmonics filter 4 to reduce the 3rd harmonic of the transmitting device. When irradiating metal products having a crack-shaped defect, the 3rd harmonic of the surroundings is generated, which enters the antenna of the receiver 6, and through a filter 7 that suppresses the 1st harmonic of the surroundings to prevent overloading of the input stages of the receiver, at which 3- I am the harmonic of the surroundings in these receiving stages, and through the amplifier 8 it enters the second input of the SFD 9, the first input of which supplies the voltage of the local oscillator of the SFD formed (circled in Fig. 1, 2, 3 by a dashed line) connected in series by a master oscillator 1, a triple hour The notes of the generator 10 and the variable phase shifter 11. The frequency of the voltage supplied to the first input of a local oscillator 9 SFD half the frequency of the input voltage (3rd harmonic AP) input to the other input of SFD 9.

At the output of the SFD 9, a signal appears that is proportional to the amplitude of the received 3rd harmonic of the surroundings that arose in a defect in a metal product. This is possible only with synchronous-phase processing of the input and heterodyne voltages. The signal at the output of the SFD 9, which is pulsed, enters through the filter and amplifier 12 to the device for processing this signal 13 and the indicator 14. The need to pass the output signal of the SFD 9 through the filter 12 is associated with the need to reduce the influence of network and industrial noise and spurious modulation effects on this signal product details.

To increase the signal-to-noise ratio of the received signal at the same time as the ES, the diagnostic object is exposed to the sound source using the inputs to the device of FIG. 1 of the low-frequency generator 15, the low-frequency power amplifier 16, the source of mechanical impact 17 (see Fig. 2), and the output of the low-frequency generator 15, the voltage is supplied to the processing device 13 to synchronize and correlate the additional mechanical effect on the metal product.

To increase the likelihood of detecting the location of a defect in a metal product, an improvement of the device of FIG. 1 by introducing the blocks of amplitude modulation ES, shown in FIG. 3, including a modulator 18 and a modulating generator 19. Using these blocks, amplitude modulation of the CS is performed, thereby increasing the coefficient of nonlinear transformation of the CS on the nonlinearities of the crack of the metal product, which increases the signal-to-noise ratio of the received 3rd harmonic signal and increases the likelihood of correct detection .

The master oscillator 1 is common for the probe signal generator and for the SFD local oscillator signal with the required frequency ratio of 2 to 1 for the normal operation of the SFD 9. This provides in-phase processing of the received 3rd harmonic signal of the probe signal and the SFD local oscillator signal (with a frequency of half that frequency of the received 3rd harmonic of the probe signal from the defective object).

The use of SFD 9 in systems where the receiving and transmitting devices are located next to each other greatly simplifies the synchronous receiver, since the local oscillator frequency is formed as the frequency of the transmitter master oscillator multiplied by the required number of times. A synchronous receiver, as is known, has increased noise immunity and can be considered as a superheterodyne with zero intermediate frequency.

To confirm the operability of the method and the device that implements this method, a device model was created. Key layout features:

- frequency of the probing signal (ZS) - 300 MHz,

- ZS output power - 5 W,

- the accepted harmonic is the third,

- receiver sensitivity - -120 dB / W,

- polarization of the antennas is linear.

A simplified layout diagram indicating the operating frequencies is shown in FIG. 4, where the frequency of the input voltage SFD 9 from the local oscillator SFD F ₃ = 150 MHz × 3 = 450 MHz, and the frequency of the received signal of the 3rd harmonic of the surroundings F ₄ = 150 MHz × 2 × 3 = 900 MHz.

As the objects of study, parts of the defective side frames of freight cars with an external crack and an injection crack were used.

The transmitting antenna 5 and the antenna of the receiving device 6 were made of combined square vibrators with corresponding reflectors. Antenna polarization - variable linear.

When the side frames were irradiated with a signal from the antenna of the generator 6 (with variable linear polarization), a periodic blow was made with a wooden or rubber sledgehammer on the frame. On the indicator of the receiver 14 after the processing device 13 (in which digital processing was used for synchronization and correlation processing), along with the light and sound signals, a graph was obtained (see Fig. 5) of the envelope of the accepted 3rd harmonic of the ES that arose in the defect during impacts with a wooden mallet on a defective side frame of a freight railroad car.

An analogue of the method of using periodic blows with a wooden or rubber sledgehammer on the frame can be the use of vibration effects from irregularities of the wheel, railroad tracks and rail joints that occurs when the car moves.

The authors studied the influence of the amplitude modulation of the pollutant on the effectiveness of the proposed method for the diagnosis of defective metal products. As a result, it was found that the use of amplitude modulation of the ES makes it possible to carry out diagnostics remotely during the movement of a railway car, since it does not require mechanical contact with the diagnostic object. Remote diagnostics of wagons can be carried out using a stationary diagnostic point located next to the tracks, with instant transmission of the received data to the dispatcher or the driver.

Claims (3)

1. A method for detecting and controlling defects in metal products, in which the metal product is scanned with a probe signal generated by the transmitting device, and the signal that appears in the defective metal product is received using the receiving device, characterized in that the probe signal is formed in the form of a 1st harmonic signal , and the 3rd harmonic of this signal arising in the defect is taken as reflected from the metal product. 2. The method according to p. 1, characterized in that, together with a probing signal, the metal product carries out simultaneous mechanical action (shock, vibration, etc.). 3. The method according to p. 1, characterized in that the amplitude-modulated 1st harmonic of the probe signal is used as the acting signal on the metal product.

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