LOW MAINTENANCE RAIL MONITORING PROBE

Abstract

An ultrasonic probe for non-destructive testing of a rail, said probe comprising a housing; an insert comprising an ultrasonic transducer and a polycarbonate shoe having a face for contacting a rail; and a compressed spring for exerting a downward force on said insert; the system further comprising a plate with a restraining flange around an aperture to prevent the polycarbonate shoe from extending more than a preset fixed amount through the aperture.

Claims

1. An ultrasonic probe for non-destructive testing of a rail, said probe comprising a housing; an insert comprising an ultrasonic transducer and a polycarbonate shoe having a face for contacting a rail; and a compressed spring for exerting a downward force on said insert; the insert being configured such that an upward force on the face of the polycarbonate shoe greater than the downward force exerted by the compressed spring forces the insert up into the housing, the system further comprising a modified plate 30′ with flanges of the modified plate 30′ restraining the probe 10 and preventing the shoe 20 from being forced further out of the housing such that an equilibrium is reached wherein the face of the shoe 20 is worn away to conform to the profile of the track 1 around an aperture for preventing the polycarbonate shoe from extending more than a preset fixed amount through the aperture thereby reducing the number of shoe replacements and increasing the distance traveled between shoe replacements than was previously possible, thereby reducing number of shoes required, downtime and maintenance costs.

2. The ultrasonic probe of claim 1, wherein the polycarbonate shoe is several millimeters thick and the preset amount is less than 1 mm.

3. A system for ultrasonic inspection of a railway track comprising the ultrasonic probe of claim 1 and further comprising a water reservoir for providing a film of water between said face of the shoe and a surface of the rail being inspected.

4. The system of claim 3 further comprising a suction system for sucking water from the rail after the probe to recycle said water back to said reservoir.

Description

BRIEF DESCRIPTION OF FIGURES

[0029] For a better understanding of the invention and to show how it may be carried into effect, reference will now be made, purely by way of example, to the accompanying Figures, wherewith it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention.

[0030] In the drawings, like components are generally designated by like reference numerals, wherein:

[0031] FIG. 1 is a photograph of a Scamnaster sled attached to the axles of a pair of bogey wheels of a wagon.

[0032] FIG. 2 is a schematic isometric view sled over a rail, showing an array of ultrasonic probes positioned over the rail, with magnetic alignment means upstream and downstream of the array for holding the sled over the rail in correct alignment therewith.

[0033] FIG. 3 is a schematic close-up view of a section of the sled showing a probe in a socket, a spring for forcing the probe down into the socket, and a plate with flange that prevents the probe from being forced downwards more than a present amount;

[0034] FIG. 4a shows a prior art probe with a polycarbonate shoe in contact with a rail;

[0035] FIG. 4b shoes the prior art probe of FIG. 4a with the polycarbonate shoe largely worn away;

[0036] FIG. 5 shows a modification of the mounting of the probe that includes a cover plate with flange, that enables the probe to be raises against helical springs if debris on the rail is encountered, but which prevents the springs forcing the probe against the track once a preset amount of wear has occurred;

[0037] FIG. 6 is an enlarged isometric projection of a previously used plate;

[0038] FIG. 7 is an enlarged isometric projection of a novel plate disclosed herein;

[0039] FIG. 8 shows a probe, plate and mounting cables in the laboratory, and

[0040] FIG. 9 shows the probe, plate and ends of cables disconnected from the sled (not shown) and suspended by the cables above the gravel surrounding a rail.

DESCRIPTION OF EMBODIMENTS

[0041] Ultrasonic testing transducers in sled type systems are protected with a special solid material also called a “shoe” to protect the transducer from any damage that might be caused by hard debris such as stones and the like on the rail surface. The show is made of a polymer that is partially transparent to ultrasonic signals. It does, however, attenuate the signal somewhat.

[0042] In the Scanmaster system described in PCT/IL2016/05065 titled “Improved Rail Testing System” incorporated herein by reference, the ultrasonic probe comprises an ultrasonic transducer and a protective shoe made of a polycarbonate that has a high ultrasonic transmissivity. The probe is mounted within a housing and a compressed spring, typically a helical spring forces the probe against the rail. An opposing pressure beyond that of the spring forces the probe into the housing, so the probe is retracted as it traverses debris on the rail and the like. Such shoes have very high wear rare due to constant contact with the rail surface during testing and require frequent replacement. As a standard maintenance procedure, the protecting shoe is typically replaced every 50-70 km depends on the line condition. When monitoring older lines with a lot of corrosion or tracks in sandy areas, the surface wear on the show is even higher and replacement is required more frequently. The frequent replacement of the polycarbonate shoe is costly. This is not only due to the inherent cost of the material, but also since the testing has to be stopped whilst the shoes are replaced, so the overall costs include labor and downtime which is typically about an hour, since recalibration is required. With reference to FIG. 1 a photograph of Scanmaster's prior art sledge attached to a pair of axles of a wagon is shown. The sledge is configured to slide along the rail.

[0043] Referring to FIG. 2, a schematic illustration of the prior art sled is shown. Prior art sled consists of an array of ultrasonic probes suspended above a rail, and a magnetic alignment means for keeping the sled aligned with a rail. In this instance, the array is linear.

[0044] Referring to FIG. 3, each ultrasonic probe 10 sits in a slot within the sled 14 and sprung loaded springs 12 enable the probe to retract if it goes over stones and other debris on the track 16. A flange 18 with an aperture provides as a cap over the transducer slot. The flange 18 is bolted down by spring bolts 12 that enable the probe 10 and flange 18 to rise up in the sled if a force is applied to the face of the probe, such as if the probe is dragged over stones or other debris.

[0045] FIGS. 4a and 4b show the prior art ultrasonic probe 10 coupled to the rail 16 by the polycarbonate shoe 20 and a film of water 22 that both provides good ultrasonic contact and lubricates the face of the polycarbonate shoe 20, to some extend reducing wear thereof.

[0046] As shown schematically in FIG. 4a, in the prior art, a polycarbonate shoe 20 is forced against the track 16 by the helical spring 12 of the spring bolts. The contact of the shoe 20 with the track 16 causes the polycarbonate face 20 of the shoe to be worn away. To some extent, flooding the track with water 22 reduces the wear and maintains good ultrasonic transmission.

[0047] Nevertheless, a shown in FIG. 4b, the polycarbonate shoe 20″ is worn away and needs periodic replacement. Such shoes have very high wear rare due to constant contact with the rail surface during testing and require frequent replacement. Thus, typically, as a standard maintenance procedure, the protecting shoe of the system described in PCT/IL2016/05065 titled “Improved Rail Testing System” is typically replaced every 50-70 km.

[0048] With reference to FIG. 5, the mounting of the probe 10 within the sled 14 by the spring loaded bolts 12 is achieved by means of a plate 30 to which the probe 10 is bolted. Plate 30, which is shown in greater detail in FIG. 6, is restrained by the spring loaded bolts 12 such that the probe 10 and plate 30 may be moved upwards by a force on the shoe of the probe.

[0049] To prevent the show from being totally removed, a modified plate 30′ as shown in FIG. 7 was substituted for the plate 30 of FIG. 6. In modified plate 30′, the flange to which is bolted to the sled 14 with the spring loaded bolts 12 protrudes below the socket for the probe 10. This prevents a preset thickness of the shoe 20, typically 2-3 mm, from being worn away.

[0050] Consequently, after about 0.5 mm to 1 mm of the face of the shoe is worn away and conformed to the surface of the track, the flanges of the plate 30′ restrains the probe 10 and prevents the shoe 20 from being forced further out of the housing.

[0051] Consequently an equilibrium is reached wherein the face of the shoe 20 is worn away to conform to the profile of the track 16 and contact with the track is maintained by a thin film of water 20 from the water system that sprays water on the track upstream of the probe and sucks excess water off the track downstream of the probe. The polycarbonate or similar shoe 20 and the thin film of water 11 provides a medium for ultrasonic contact that allows transmission of the ultrasonic signals from the probe 10 to the rail 16 and reflected back from the rail 16 and flaws therein to the probe 10. The water 22 also lubricates and minimizes further wear.

[0052] FIG. 8 shows a photograph of the modified probe in the laboratory, and FIG. 9 shows the probe in the field, by a rail during testing in Spain during December 2016 where it was surprisingly found that modified probe design including the plate of FIG. 7 resulted in the probe shoes requiring replacement only twice in 5 days of testing during which 1500 km of track was monitored. Thus the number of shoe replacements was one tenth that previously required modified probe design was able to travel ten times the distance between shoe replacements than was previously possible. This saves on shoes, but also on downtime and maintenance costs.

[0053] Persons skilled in the art will appreciate that the present invention is not limited to what has been particularly shown and described hereinabove. Rather the scope of the present invention is defined by the appended claims and includes both combinations and sub combinations of the various features described hereinabove as well as variations and modifications thereof, which would occur to persons skilled in the art upon reading the foregoing description.

[0054] In the claims, the word “comprise”, and variations thereof such as “comprises”, “comprising” and the like indicate that the components listed are included, but not generally to the exclusion of other components.