RU2370391C2 - Ultrasonic method for detection of cracks in walls of bolt openings of railway rails that are non-testable from rolling surface - Google Patents

Abstract

FIELD: instrument making.

SUBSTANCE: invention is related to methods of nondestructive check. In ultrasonic method of cracks detection in walls of bolt openings of railway rails, which are non-testable from rolling surface, according to the first version, in controlled rail with the help of direct transmit-receive piezoelectric converter located near opening so that electroacoustic screen lies on conventional line passing through centre of opening, perpendicularly to surface of rail web, pulse ultrasonic radiations are emitted, echo-signals reflected from opposite surface of web are received, converter is displaced along surface of rail web around opening, crack is detected based on disappearance or reduction of echo-signal. According to the second version, two inclined piezoelectric converters are used, which operate in separate mode of transmit-receive, located near opening so that acoustic axes of converters pass along tangent to opening walls and are directed towards each other so that signal reflected from opposite surface of web, arrives to receiver, ultrasonic vibrations are emitted, echo-signals reflected from web surface are received, converters are displaced along surface of rail web around hole, crack is detected based on disappearance or reduction of echo-signal.

EFFECT: improved safety of traffic, higher credibility of cracks detection in walls of bolt openings.

2 cl, 3 dwg

Description

The invention relates to ultrasonic inspection, and more particularly to ultrasonic (ultrasound) inspection of bolt holes (b / o) of railway rails (railways) with surface defects.

Fatigue radial crack emerging from the bolt hole in the neck of the rail (defect 53.1 according to the "Classification of defects of rails NTD / CP-1-93. M .: Transport, 1993, p.10), is one of the reasons for removing the rail from the track. As a result of the development of such a crack, a piece of the rail head is punctured from the end, which can lead to the rolling stock coming off (V. Tyrin et al. Crack resistance of the rail in the area of bolt holes. // Vestnik VNIIZhTa, 1991, N 6, p. 36-40 ) Therefore, the development of methods for the timely detection of these fatigue cracks is the most important task. The invention has no analogues, because all known methods of ultrasonic testing of bolt holes rails are applicable only from the rolling surface and are not suitable for defective rails, which are very numerous in the way (defects 10.1, 17.1, 18.1, 47.1, 49.1 according to the "Classification of rail defects NTD / CP-1-93", p.5, 6, 9 ) These bolt holes for a long time (before the planned replacement of the rails) remain unverified, which is unsafe for the movement of trains.

The first objective of the invention is to improve traffic safety by additionally monitoring bolt holes that are not currently being tested. In addition, all known methods are noise-resistant to violations of drilling technology (double drilling, ovality, rubbing, burrs, not chamfered, extra holes, deep marking marks) and require additional verification (currently visual) to avoid rejection. Given that not every crack can be detected visually, the second objective of the invention is to increase the reliability and simplify the process of detecting cracks in the walls of bolt holes.

This goal is achieved by the fact that pulsed ultrasonic vibrations excite from the surface of the neck of the rail, and not from the rolling surface, which, firstly, eliminates the influence of surface defects, and secondly, allows you to not pay attention to interference due to violation of drilling technology, as It is not the bolt hole itself that is voiced, but the metal of the neck next to it. In addition, the ultrasound method is more reliable than the visual one.

The claimed method uses a mirror shadow method (ZTM) ultrasonic control. The method consists in the fact that in a controlled rail with the help of a direct separate-aligned (PC) probe located near the hole so that the electro-acoustic screen lies on a conditional line passing through the center of the hole, longitudinal ultrasonic vibrations are perpendicular to the surface of the neck of the rail, receive reflected from the opposite neck surface, echoes move the PC probe over the rail neck surface around the hole. If there is no crack on the screen of the flaw detector there is a "bottom" echo signal. At the moment when the radial crack is between the emitting and receiving piezoelectric plates, the “bottom” signal disappears or decreases, which is a sign of crack detection. In the second embodiment, two inclined piezoelectric transducers with an input angle α are used, operating in a separate radiation-reception mode, located next to the hole so that the acoustic axes of the transducers are tangent to the wall of the hole.

The transducers are directed towards each other so that the echo signal reflected from the opposite surface of the neck, fell on the receiver. The distance between the probes depends on the input angle B = tg (α °) H2, where α is the input angle of ultrasonic vibrations;

H is the thickness of the neck.

If there is no crack on the screen of the flaw detector there is a "bottom" echo signal. At the moment when the radial crack is between the transducers, the “bottom” signal disappears or decreases, which is a sign of crack detection.

The drawing shows a sounding scheme of holes with radial cracks.

From the surface of the neck of the rail 1 with the hole 2 and radial cracks 3 and 4, transverse ultrasonic vibrations 6 are radiated with the help of an inclined PI PEP 5 6. Move the PEP 5 fixed on the guide 7 along the surface of the neck 1 around the b / o 2. If there is a crack 3 on the flaw detector screen displays an echo from an angular reflector formed by the surfaces of the crack and the rail neck.

From the surface of the neck of the rail 1 with the hole 2 and radial cracks 3 and 4 using direct PC probe 8 emit longitudinal ultrasonic vibrations 9, receive the echo signals reflected from the opposite surface of the neck 10. Move the PC probe 8, mounted on the guide 7, along the surface of the neck 1 around b / o 2. At the moment when the radial crack 4 is between the radiating 11 and the receiving 12 piezoelectric plates, the “bottom” signal disappears or decreases, which is a sign of crack detection.

In the second embodiment, transverse ultrasonic vibrations 6 are emitted using an inclined PI probe 5. The echo signal 13 reflected from the opposite surface of the neck goes to the receiver 14. The system, consisting of transducers 5 and 14, mounted on the guide 7, is moved along the surface of the neck 1 around b / o 2. At the moment when the radial crack 3 is between the transducers, the "bottom" signal disappears or decreases, which is a sign of crack detection. The claimed method (options) is successfully used when conducting field examinations b / o railway. rails by employees of the combined wagon of flaw detector No. 403 of the Oktyabrskaya railway station Cracks were discovered that are difficult to detect visually in the field. For its implementation, the devices shown in the attached photographs were assembled. In the photo 1 device according to the second variant of the method. In photo 2, the device according to the first embodiment.

Devices are assembled from improvised materials:

a guide with a diameter of 35 mm, a handle of arbitrary length and shape, fastener parts. Used typical probes. To implement the claimed method in practice, ultrasonic testing D. rails without much difficulty can be made more convenient and beautiful devices.

Claims (2)

1. Ultrasonic method for detecting cracks in the walls of the bolt holes of railway rails that are unsuitable from the rolling surface, which consists in the fact that in the controlled rail using a direct separately combined piezoelectric transducer located next to the hole so that the electro-acoustic screen lies on a conditional line passing through the center of the hole, perpendicular to the surface of the neck of the rail emit pulsed ultrasonic vibrations, take reflected from the opposite surface cervical echoes moved converter according neck rail surface around the opening, the presence of cracks is judged by the disappearance or reduction of the echo. 2. An ultrasonic method for detecting cracks in the walls of bolt holes of railway rails that are unsuitable from the rolling surface, which consists in using two inclined piezoelectric transducers operating in a separate radiation-receiving mode, located next to the hole so that the acoustic axes of the transducers pass along tangent to the wall of the hole and directed towards each other so that the signal reflected from the opposite surface of the neck, hit the receiver, emit ltrazvukovye vibrations reflected from the receiving surface of the neck of the echo signals, converters for moving the neck rail surface around the opening, the presence of cracks is judged by the disappearance or reduction of the echo.

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