US3122661A

US3122661A - Liquid trough for ultrasonic coupling to rail

Info

Publication number: US3122661A
Application number: US79921A
Authority: US
Inventors: Ivan L Joy
Original assignee: Chemetron Corp
Current assignee: Chemetron Corp
Priority date: 1957-04-24
Filing date: 1960-12-30
Publication date: 1964-02-25
Anticipated expiration: 1981-02-25

Description

Feb. 25, 1964 l. JOY

LIQUID TROUGH FOR ULTRASONIC COUPLING TO RAIL Original Filed April 24, 195'? INVENTOR.

W YWZcQ/Z/a'm United States Patent 3,122,661 LIQUID TRQUGH FOR ULTRASUNIC COUPLING T0 RAIL Ivan L. Joy, Topeka, Kans., assignor to Chemetron Corporation, Chicago, 111., a corporation of Delaware Original application Apr. 24, 1957, Ser. No. 654,941, new Patent No. 2992553, dated July 18, 1%1. Divided and this application Dec. 30, 1960, Ser. No. 79,921

4 Claims. (Cl. 316-457) This application is filed as a division of application Serial No. 654,941, filed April 24, 1957, which issued July 18, 1961 as US. Patent No. 2,992,553. This invention relates to a trough for application to track rail for maintaining a coupling liquid between an emitter of ultrasonic elastic wave energy and the rail, and more particularly, is concerned with a trough for application in the continuous progressive ultrasonic inspection of track rail.

The prior art is replete with ultrasonic coupling arrangements for the stationary testing of objects, but none of these may practicably be employed in the continuous progressive testing of rail. Similarly a number of coupling arrangements for continuous progressive testing with ultrasonics are known; but they, too, are subject to one or more of the exacting practical difficulties that experience indicates are inherent in the continuous progressive testing of rail. These difficulties must be overcome in order to realize an effective ultrasonic rail testing system.

Some of the more important problems are pointed up briefly in order to provide a firm appreciation of the importance of the advances represented by the present invention.

The rail surface or surfaces through which the ultrasonic energy must pass not infrequently are rough, or even rusty, and of varying contour; hence, to avoid damage to the piezoelectric crystal that is usually employed as the emitter of the ultrasound, and to allow for necessary crystal movement, the crystal and rail surface must be appropriately spaced apart. The provision of an adequate liquid path between the facing surfaces of the emitter and the rail which are undergoing continuous relative movement is a difficult task.

One approach is the use of a confined static column of liquid that is progressed with the crystal, but, due to heat and turbulence, the liquids used in prior art arrangements of this nature have a pronounced tendency to release gas bubbles which interfere with the transmission of the ultrasound. Also, rough and ragged rail portions trap air bubbles which are carried into contact with and released into the coupling liquid. This effect is aggravated in the instances where the arrangement is such that the gas bubbles are permitted to collect on the face of the crystal. In the continuous progressive testing of rail, the emitter and associated confining chamber for the coupling liquid may reach temperatures on the order of 150 F.; and this, of course, results in a severe gas bubble problem. Addi tionally, vibration and shock effects which are practically unavoidable in this type of rail testing, agitate the coupling liquid and also cause gas bubbles.

Another approach is to flow a stream of coupling liquid between the facing surfaces of the emitter and the rail. Any turbulence of the flow stream, however, impairs its coupling effectiveness and induces the generation and release of gas bubbles. In rail testing, the ragged and rusty 3,122,661 Patented Feb. 25, 1964 condition of the rail surfaces, in combination with the movement of the car along the rail, has a disturbing influence on the flow stream of the coupling liquid. Furthermore, the present-day difiiculties of storing and transporting large quantities of coupling liquid on a detector car make it imperative to reclaim and recirculate the coupling liquid; but in this process, many additional gas bubbles and impurities are introduced; and the liquid must be cleaned quickly and efficiently before it can be reused.

In locations where the rail surfaces are very rough and uneven, it is extremely difficult to confine the coupling liquid in a pool on the rail; but the development of an adequate pooling of the coupling liquid is vital if an effective reclaiming system is to be achieved.

It is the principal object of the present invention to provide coupling liquid trough arrangements that overcome the above-noted difficulties and that permit a more effective and reliable ultrasonic system for the continuous progressive testing of rail.

Other objects and advantages of the invention will become apparent during the course of the following description.

In the accompanying drawings forming a part of this specification and in which like numerals are employed to designate like parts throughout the same:

FIG. 1 is a fragmentary perspective view, with parts broken away and sectioned, of a composite trough type ultrasonic coupling arrangement suitable for simultaneous side rail and top rail testing; and FIG. 2 is a developed sectional view through the principal parts of the arrangement of FIG. 1.

Referring now to the drawings a composite coupling apparatus capable of simultaneous side rail and top rail coupling may be employed to facilitate complete inspection of the rail. In FIGS. 1 and 2, the rail shoe is shown in the form of a composite trough, one side of which, as indicated at 101, slides along the top surface of the rail adjacent the field edge at a point that is relatively free of rolling and wear difficulties, and the other side of which, as indicated at 102, slides along the gauge edge of the rail at the lower region of the rail head; and the coupling liquid is confined between these points. The composite trough includes an inner set of walls 103 which engage the various portions of the rail to form the liquidconfining chamber 104 and a two-part outer set of walls 1% and 165 spaced from the inner set of walls and defining a two-part liquid-collecting chamber 1% and 106 which substantially surrounds the outer margins of the confining chamber 164 at the points of contact with the rail surface. Actually, the chambers 106 and 106 are completely separate although, if desired, they can be connected across the top surface of the rail at the opposite ends of the trough.

The composite trough may be operated in either of two different ways. According to one arrangement wherein a pool of coupling liquid is maintained within the trough, an air blower (not shown) is connected through lines 108 and 109 (FIG. 1) to blow air into the two-part collecting chamber 106 and 106 and develop a sweeping action that effectively prevents coupling liquid from escaping into chambers 106 and 166 from confining chamber 104. Similarly an air blower (not shown) may be connected to line 110 to force air into a chamber provided at the end of the trough, and the air will flow through a tapered chute 111 into the main confining chamber to develop a similar sweeping action at the end of the trough and prevent coupling liquid leakage at these points. While the entire trough is not shown in the drawings, its opposite ends are preferably identical in construction and arrangement, and it will be understood that a line 119 and chute 111 are provided at each end of the trough. With air jets blowing into the trough through lines 1%, Hi9, and 110, a pool of Water may be effectively established within the trough, the water being introduced in the illustration through the supply lines 129 for the crystal holders 112 and 113.

If it is desired toutilize a static pool of liquid, the arrangement as described thus far is employed with the understanding that a limited flow of liquid will be introduced through the crystal holders to initially establish the pool and to maintain it as desired. If it is desired to circulate the pool of liquid, however, a plate 115 is located along the length of the confining chamber res to form an auxiliary chamber 116, in which the water is collected and pumped through a return line 117 which connects with one or both ends of the auxiliary chamber 116. The plate 115 is apertured as at 118 to permit the pooled liquid to flow from the confining chamber 104 into the auxiliary chamber 116. The principle of operation for the composite trough, as described above, depends upon air jets for sweeping the liquid inwardly and maintaining a pool within the trough and is the most efiective system for minimizing coupling liquid loss. Sweeping with air jets substantially eliminates any residual deposit of coupling liquid film such as can occur with reclaiming arrangements that do not employ air jet sweeping.

An alternative principle of operation for the composite trough of FIGS. 1 and 2 is contemplated wherein the supply pipes lltl at the opposite ends of the trough still blow air into the trough to provide sweeping air jets at the opposite ends, but supply pipes 198 and 1&9 apply suction to the various portions of chamber 1&6 and 196 In this case, return line 117 may or may not be employed, as desired, it having no significant effect upon the operation. With this latter type of operation, the crystal assemblies must provide a suiiiciently strong stream of water to maintain continuous coupling, bearing in mind that the stream is continuously and immediately reclaimed and will have substantially no chance to form a pool of liquid within the trough.

The flexibility of application of this trough is apparent, and the particular crystal assembly employed is of little importance as the trough itself can provide the desired coupling and reclaiming action. A variety of coupling arrangements could be utilized within the trough, but a special form of coupling device is shown at 112 for testing the top surface of the rail. The device utilizes an elongated vertical tube 120, the closed top end of which carries the crystal 3%). The inlet 129 to the tube is located approximately at the elevation of the face of the crystal to flow a stream of coupling liquid directly across the crystal face and sweep it free of any gas bubbles that may tend to collect. To encourage this sweeping action, the tube 120, according to the present invention, includes a U-shaped tube 121, the upper leg of which communicates with the main passage of the tube 120 approximately at the elevation of the crystal face and the lower leg of which communicates at an intermediate level of the tube 126. The U-tube 121 provides an auxiliary flow path that encourages transverse how of liquid across the crystal face.

Ultimately, the stream of liquid entering through inlet line 129 must flow downwardly through the tube 120 and into the trough, and the rate of flow should be sufiicient to prevent gas bubbles from rising in the tube 120. A flow the exception that the length of the tube is considerably shorter and the U-tube is omitted. The problem of gas bubbles collecting on the crystal face in the case of the holders 113 is substantially avoided by virtue of the fact that the crystal face is arranged in a vertical plane and is spaced laterally from the rail, and any bubbles that may develop at the surface of the rail would rise in the pool within the trough and would not return through the holder tube.

It should be understood that the description of the preferred form of the invention is for the purpose of complying with Section 112, Title 35, of the United States Code, and that the appended claims should be construed as broadly as the prior art will permit.

1 claim:

1. A coupling liquid trough for use with an ultrasonic system in the progressive testing of track rail and comprising continuous liquid confining wall means contacting and cooperating with top and side surface portions of said rail to form a liquid confining chamber, separate electromechanical transducers mounted in said chamber in working relationship with the top surface and the side surface of said rail, additional liquid confining wall means connected in spaced relation to said first-mentioned wall means to provide liquid collecting chamber means along the top and side surface portions of said rail, means for supplying coupling liquid between said transducers and the rail surfaces that are in working relationship therewith, and blower means connected to said collecting chamber means to prevent escape of coupling liquid between the contacting regions of said additional wall means and said rail.

2. A coupling liquid trough for use with an ultrasonic system in the progressive testing of track rail and comprising liquid confining wall means contacting and cooperating with top and side surface portions of said rail to form a liquid confining chamber; separate electromechanical transducers mounted in said chamber in working relationship with the top surface and the side surface of the rail; means for supplying coupling liquid between said transducers and the rail surfaces that are in working relationship therewith; a perforated plate extending substan tially horizontally through the lower part of said chamber to provide a collection compartment therebeneath, liquid pumping means connected to said compartment for reclaiming liquid collected therein; additional liquid confining wall means connected in spaced relation to said first-mentioned wall means to provide liquid-collecting chamber means along the top and side surface portions of said rail; and suction blower means connected to said collecting chamber means and continuously exhausting the same to prevent escape of coupling liquid between the contacting regions of said additional wall means and said rail.

3. A coupling liquid trough for use with an ultrasonic system in the progressive testing of track rail and comprising liquid confining wall means contacting and cooperating with top and side surface portions of said rail to form a liquid confining chamber; separate electromechanical transducers mounted in said chamber in working relationship with the top surface and the side surface of the rail; means for supplying coupling liquid between said transducers and the rail surfaces that are in working relationship therewith; a perforated plate extending substantially horizontally through the lower part of said chamber to provide a collection compartment therebeneath, liquid pumping means connected to said compartment for reclaiming liquid collected therein; additional liquid confining wall means connected in spaced relation to said first-mentioned wall means to provide liquid-collecting chamber means along the top and side surface portions of said rail; and air-jet blower means connected to said collecting chamber means and continuously sweeping the same to prevent escape of coupling liquid between the contacting regions of said additional Wall means and said rail.

4. A coupling liquid trough for use in the progressive testing of rail and comprising an endless retainer wall having an edge configuration matched to the surface of the rail and engageable therewith to provide a liquid confining chamber adjacent to such rail surface, means mounting an ultrasonic transducer in said chamber in working relationship with said rail surface, an outer retainer wall alongside sat-id endless retainer wall and cooperable therewith to define a liquid collecting chamber extending along the margin of said confining chamber, means for establishing a solid column of coupling liquid at a location in said confining chamber between said crystal and rail, and means for blowing air into lower regions of said collecting chamber to develop an air sweeping action around 6 said confining chamber and prevent loss of liquid therefrom.

References Cited in the file of this patent UNITED STATES PATENTS 2,545,101 Meunier Mar. 13, 1951 2,636,569 Smith Apr. 28, 1953 2,672,753 Drake Mar. 23, 1954 2,715,450 Bliss et al. Aug. 16, 1955 2,888,581 Pahud May 26, 1959 2,951,365 Legrand Sept. 6, 1960 2,956,185 Von Stocker Oct. 11, 1960 2,992,553 Joy July 18, 1961