MXPA06004542A - Method and apparatus for ultrasonic testing of an object - Google Patents

Abstract

A method for ultrasonic testing of an object, wherein at least one test moment an ultrasonic test signal (S1, S2) is transmitted into the object (2), while after a particular verification period (?t1, ?t2) measured from said test moment, an ultrasonic verification signal (S1âÇÖ, S2âÇÖ) is transmitted into the object (2), a possible echo of said test signal (S1, S2) being received from said object (2) at a particular first measuring moment, the possible echo being accepted as being the echo (E1, E2) of said test signal (S1, S2) only when the echo (E1âÇÖ, E2âÇÖ) of the verification signal is received at a particular second measuring moment. In addition, the invention provides an apparatus, evidently intended and designed for carrying out such a method and a use of such an apparatus.

Description

METHOD AND APPARATUS FOR ULTRASONIC TESTING OF AN OBJECT DESCRIPTION OF THE INVENTION The invention relates to a method for ultrasonic testing of an object, wherein in at least one test moment, an ultrasonic test signal is transmitted on the object. Such a method is known per se from the practice to detect defects present in the object, to measure the thickness of the object or the like, see for example U.S. Patent 6,055,862. The method, for example, is suitable for detecting defects in train rails and / or wear of train rails. A measuring train is then driven on the rails at a particular measurement speed. The measurement train is provided with a number of transducers designed to transmit the ultrasonic test pulses perpendicularly and at specific angles on the rails. In addition, the train is provided with detectors to receive echoes arriving from the test impulses. At the base of the echo configuration provided by these echoes, it can be determined if the defects are present in the rails, in which positions are the defects found, and at what height of the line it is. The determination of this is generally carried out by suitable electronic signal processing devices, in particular one or more Ref .: 172559 appropriately programmed computers. An advantage of the known method is that with this, an object can be checked for defects in a quick and non-destructive manner. A disadvantage of the known method is that it is relatively difficult to detect the associated echo of each sound signal transmitted in the object. For example, different interference signals that have a different source than the test signals can propagate through the object. When the measurements are made on the rails, these interference signals may comprise, for example, noise produced by the measurement train itself, for example noise formed by the wheels of the train that twist when the curves are taken. Such interference signals may make it impossible to detect the echo of a test signal. In addition, interference signals can be detected unintentionally when they are echoes of the test signals, thereby leading to an incorrect test result. Another source of alteration of the measurement are the test signals themselves, in the case that the method is carried out with more than one test signal. In this case, it is difficult to distinguish the echoes of the different test signals from one another, in particular when the test signals are transmitted successively along a part of the object being tested in a relatively short period of time.

The object of the present invention is an improvement of the method for ultrasonic testing of an object. The object of the invention is in particular a method with which the test can be carried out relatively accurately. For this purpose, the method according to the invention is characterized by the features of claim 1. In at least one test moment, an ultrasonic test signal is transmitted on the object. After a particular verification period, measured from the time of testing, an ultrasonic verification signal is transmitted on the object. A possible echo of this test signal is received at a particular first measurement moment. This echo is accepted as being an echo of the mentioned test signal only when an echo of the verification signal is received at a second measurement moment. In this way, the object can be tested ultrasonically in particular, exactly. At the base of the verification signal, it is then determined whether an ultrasonic signal received from the object is currently an echo of the test signal. If a received signal does not arrive from a test signal, frequently, no echo of a verification signal will be received. In this case, the received signal can be rejected. The possible echoes of the test signals are accepted after receipt of the associated echoes of verification signals only. With this method, the interference signals can be separated well from the test signals. The acceptance of the test signal can also be considered as acceptance of the reception of the verification signal. In this case, the echo of the test signal serves to verify an echo of a verification signal issued afterwards. The parts of the test signal and test signal are then reversed. According to the invention, the method can therefore be performed in an equivalent manner, first by transmitting a verification signal on the object and then a test signal. The invention is then characterized in particular in that at least one test moment, an ultrasonic verification signal is transmitted on the object, while after a particular verification period, measured from the aforementioned test moment, an ultrasonic test signal is transmitted in the object while a possible echo of this test signal is received from the object at a second particular measurement moment, the possible echo is accepted as being the echo of the test signal only when an echo of the signal of verification is received at a particular moment of particular measurement. This method, described in claim 2, uses the same concept of the invention as the method according to claim 1 and therefore also offers the advantages mentioned above. According to a preferred embodiment, the echo echoed from the mentioned test signal is accepted as being the echo of this test signal only when the difference between the first and second measurement moment is substantially equal to the aforementioned verification period. Each test signal and an associated verification signal have been transmitted on the object with a particular intermediate verification period. When, therefore, echoes having substantially the same intermediate verification period are received from the object, these echoes can be accepted as being the echoes of this test signal and this verification signal. Through the verification period, the echo of the verification signal then proves that a particular echo belongs to a particular test signal. The invention further provides an apparatus which is characterized by the subject matter of claim 9. With this apparatus, the method according to the invention can be performed in an advantageous manner, which offers the advantages mentioned above. The apparatus can be used in different ways, for example to test objects, elements, rails, parts of vehicles, parts of aircraft and / or ships or the like.

Additionally, the elaborations of the invention are described in the subclaims. Now, the invention will be further elucidated with reference to an exemplary embodiment and the figures. In the figures: Figure IA shows schematically a timeline of a method known from the state of the art, wherein a number of test signals is periodically transmitted in the object; Figure IB shows a similar timeline as Figure 1A, the test signals are transmitted on the object with a divided period; Figure 2 shows schematically an echo configuration, which belongs to the method shown in Figures 1A and IB; Figure 3 schematically shows a timeline of a method according to the present invention; Figure 4 shows schematically an echo configuration, which belongs to the method shown in Figure 3; and Figure 5 shows an apparatus for performing an ultrasonic test method of an object. Figures 1 and 2 schematically show a known method of practice wherein a number of ultrasonic pulses are periodically transmitted in an object. The method is carried out with, for example, the measuring apparatus 1 schematically shown in FIG. 5. The measuring device 1, for example a part of a measuring train, is movable on the object 2, for example rails. The apparatus 1 is provided with a measurement and detection system 3 which is designed to introduce ultrasonic pulses into the object 2 and receive the echoes arriving from those impulses. The mentioned system 3 can be brought into adequate contact with the object 2, for example directly or indirectly, via a liquid, via air or in a different way. The measurement and detection system 3 comprises one or more transducers (not shown) for generating the ultrasonic pulses and entering them into the object, and one or more detectors (not shown) for receiving the echoes of the ultrasonic pulses. The measurement and detection system 3 is connected to a control 4 designed to process the signals received by the detectors. Preferably, the control is designed to determine from a received echo configuration, if and where possible errors, fractures, defects and other irregularities are present in the object. In addition, the control is designed to, for example, determine the thickness of the object at the base of the mentioned echoes. Such a measuring apparatus 1 is known per se from the practice, see for example US 6,055,862. During use, the measuring apparatus 1 transmits a number of test signals in the object 1, for example according to the test configuration shown in FIGS. A and IB. Figure 1 shows a timeline along which a number of ultrasonic pulses has been indicated with reference numbers SI, S2, S3. The pulses SI, S2, S3 all have the same frequency spectrum and the same pulse duration. In the present exemplary embodiment, the pulses SI, S2, S3 are successively transmitted in the object 2 with a substantially fixed test period T from the time t = 0. Therefore, the first pulse SI is transmitted at a first test moment t = 0, the second pulse S2 at the second test moment t = T and the third pulse S3 at a third test moment t = 2T. When the measuring apparatus 1 moves along the object 2 at a particular measuring speed V, the pulses SI, S2, S3 will be introduced into the object 2 at substantially fixed mutual distances. In an increase in the measuring speed V, for example twice, the test period will be reduced, for example divided, for the transmission of the pulses SI, S2, S3 in the object at the same distances, which is represented in FIG. Figure IB. To transmit the pulses at desired distances in object 2, the test period T, for example, can comprise a particular measurement time and a particular waiting time. Naturally, during use, the mentioned test period T can also be varied in different ways. For example, the test period can, for example, be varied with a particular measuring speed V of the measuring device 1. Furthermore, the test period can, for example, be adjusted to an acceleration and / or deceleration of the measuring device 1. The The measuring and detection device can, for example, be coupled to a tachometer (not shown) of the device 1. The echo signals coming from the test pulses SI, S2, S3 are received by the measuring device 1. The echo configuration associated with the echoes El, E2, E3 is represented in FIG. 2. The first echo El, which arrives from the first test pulse SI, is received at a particular first measurement moment, following a measurement period M after the first test moment t = 0. The length of this measurement period M depends inter alia on the speed of sound in the material of object 2 being tested and the dimensions of this object 2, and the speed of sound of the materials and substances present between the object 2 and the detectors of the apparatus 1. As shown in FIGS. IB and 2, the echo of the first pulse SI can, for example, reach the detector only after the second pulse S2 has been transmitted. In this case, the second pulse S2 may interfere with the reception of the echo of the first pulse. In addition, this known method is sensitive to other interference signals propagating through object 2.

Figures 3 and 4 schematically show the timelines of an exemplary embodiment of a method according to the present invention which is relatively insensitive to interference signals. As shown in Figure 3, various ultrasonic test signals SI, S2, S3, S4 are then transmitted in object 2 to particular test moments, with an intermediate test period T. The test period T between the signals of Near test SI, S2, S3, S4 is, for example, less than about 1 ms, and is more particularly in the range of 0.5 - 0.01 ms. Of course, the test period can also be about 1 ms or more, depending on the use and / or speed of measurement of the apparatus. The test periods T of the test signals SI, S2, S3, S4 can be, for example, such that the test signals are transmitted in object 2 approximately every one or a few millimeters when the apparatus moves along the object 2 at a particular speed V. Preferably, during use, the apparatus 1 moves along the object at a measuring speed V which is greater than about 10 m / s, more particularly greater than about 20 m / s. As a result, a large part of the object can be tested relatively quickly. For example, it is very disadvantageous when the measuring speed V is at least about 30 m / s while the test signals are transmitted on the object every 2 to 3 mm.

With some of the test signals SI, S2 and S4, too, the ultrasonic verification signals SI1, S2 ', S4', S4 '' are transmitted in object 2, in particular after particular verification periods? Ti,? t2, measured from the mentioned test moments. In exemplary mode, a verification signal SI 'is transmitted in a first verification period? Ti after the first test moment t = 0. A verification signal S2 'is transmitted after a second verification period? T2 from the second test moment t = T. In exemplary mode, the second verification period? T2 is longer than the first verification period? Tx to distinguish the associated echoes from each other. Two verification signals S4 'and S4"are transmitted to appropriate verification periods after the third test moment t = 2T In the exemplary mode, no verification signal is transmitted for the purpose of verifying the third test signal S3. Naturally, more test signals, with or without associated verification signals, can be introduced into object 2. Additionally, verification signals, for example, can also be transmitted prior to the associated test signals, which has not been Also, the test periods T between the test signals may be greater than the verification period? ti,? t2 mentioned.

Preferably, each test signal SI, S2 and one or more associated verification signals SI ', S2', are introduced close to each other in the object 2, so that the echoes of these signals arrive from substantially the same part of the object 2. , which returns to the verification of the extra exact test signals. Each test signal, for example, can be transmitted in the object 2 in a first position, while an associated verification signal SI ', S2' is transmitted in the object 2 in a second position adjacent to the first position. Preferably, the distance between the first and second positions is less than about 1 mm, and in particular is about 0.5 mm or less, more particularly about 0.1 mm or less. Preferably, each verification period is relatively minor with respect to the test period T of the test signals. For example, the verification period? Ti,? T2 is preferably less than about 100 μs, in particular less than about 50 μs, more particularly less than about 20 μs. The verification period, for example, may be in the range of about 1 -20 μs. When different verification periods? Tx,? T2 are used, as is the case in the exemplary mode, they may differ from each other, for example, by one or a few μs. A period of verification, for example, may take more time than approximately 10 μs, while, conversely, the other is shorter. Figure 4 shows a part of the echo configuration of the test configuration shown in Figure 3, after a good reception of the echoes El, E2, El ', E2' arriving from the test signals SI, S2 and verification signals SI ', S2'. At this point, each echo of each test signal is received at a first associated measurement moment. In exemplary mode, the received echo El, E2 of each test signal SI, S2 is verified on the basis of reception, and in particular the moment of reception of the echo The ', E2' of the associated verification signal SI ' , S2 '. The echo of each test signal SI, S2 is accepted only when the echo El ', E2' of the associated verification signal SI ', S2' is received at a second particular measurement moment and when the difference between the first and second Measurement moment is substantially equal to the aforementioned verification period. The fact is that, at least with the present exemplary embodiment, at an appropriate reception, the verification echo is received in approximately an associated verification period later than the echo of the associated test signal. In the event that a verification signal is transmitted prior to an associated test signal, at a correct reception, the verification echo is received approximately in an associated verification period sooner than the echo of the associated test signal. When no verification signal is received or at a different time than the expected time, a received, associated, alleged echo of a test signal is rejected. Preferably, the test signals and verification signals are used which are substantially equal to each other, which makes the measurement and signal processing thereof relatively accurate. In particular each test signal and each associated verification signal has substantially the same signal duration, substantially the same amplitude and substantially the same frequency spectrum so that an exact verification can be performed. On the other hand, each test signal and verification signal, for example, may differ from each other in terms of, for example, signal duration, amplitude and / or frequency spectrum. Additionally, the test signals may be mutually the same or differ in terms of pulse duration, amplitude and / or frequency. To perform the present invention, the invention additionally provides an apparatus which is preferably provided with a control, a particular computer means, the control is designed to accept an echo received at a particular measurement moment which is an echo. of a test signal SI, S2 only when an echo El1, E2 'of the verification signal SI', S2 is received at a different particular measurement moment. Preferably, the control is then designed to accept a received echo only when the difference between one and another measurement moment is substantially equal to the verification period? Ti,? T2 mentioned, which makes the apparatus particularly accurate and insensitive to interference signals. . It is self-evident that the invention is not limited to the exemplary embodiment described. Various modifications are possible within the structure of the invention as described in the following claims. For example, transducers, detectors as such can be designed and arranged in various ways. The measuring apparatus 1 can additionally be designed in different ways, which for example is dependent on the object to be tested with it. Additionally, the different test signals for example can be distinguished from each other well when the length of the verification period is varied with a number of test signals that are transmitted successively. In addition, for example, some test signals can be provided with verification signals and others not. additionally, for the purpose of verifying a test signal, for example various associated verification signals may be generated, with easily recognizable intermediate verification periods. The test signals may comprise different signals, for example signals with a relatively short pulse duration of a few μs or less. In addition, the signals can be transmitted perpendicular to and / or at different angles in the object to be tested. In addition, one or more verification signals, for example, can be transmitted in the object prior to and / or after at least one test signal for verification of a possible echo of this test signal. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (12)

CLAIMS Having described the invention as above, the contents of the following claims are claimed as property:

1. Method for ultrasonic testing of an object, characterized in that at least at a test moment an ultrasonic test signal is transmitted on the object, whereas after a particular verification period measured from the time of testing, an ultrasonic verification signal is transmits on the object, a possible echo of the test signal is received from the object at a particular first measurement moment, the possible echo is accepted as being the echo of the test signal only when an echo of the verification signal it is received in a second moment of particular measurement.

2. Method for ultrasonic testing of an object, characterized in that at least one test moment an ultrasonic verification signal is transmitted on the object while after a particular verification period measured from the time of testing, an ultrasonic test signal transmitted in the object, a possible echo of the test signal is received from the object at a second particular measurement moment, the possible echo is accepted as being the echo of the test signal only when an echo of the signal of verification is received at a particular moment of particular measurement. Method according to claim 1 or 2, characterized in that the possible echo of the test signal is accepted as being the echo of this test signal only when the difference between the first and second measurement moment is substantially equal to verification period. 4. Method according to any of the preceding claims, characterized in that the test signal and each associated verification signal are equal to each other and have in particular the same signal duration, the same amplitude and the same frequency spectrum. Method according to any of the preceding claims, characterized in that the test signal is transmitted in the object in a first position, while the verification signal is transmitted in the object in a second position adjacent to the first position. 6. Method according to claim 5, characterized in that the distance between the first and second position is less than about 1 mm, in particular it is about 0.5 mm or less, in particular about 0.1 mm or less. Method according to any of the preceding claims, characterized in that the verification period is less than about 100 μs, more in particular less than about 50 μs, more in particular less than about 20 μs. 8. Method according to any of the preceding claims, characterized in that a number of test signals is transmitted successively in the object, in particular with intermediate test periods which are greater than the verification period, while after and / or prior to at least one of the test signals, at least one associated verification signal is transmitted in the object. 9. Apparatus, characterized in that it is evidently proposed and designed to perform a method according to any of the preceding claims. Apparatus according to claim 9, characterized in that, during use, the apparatus moves along the object at a particular measurement speed, while the measurement speed in particular is greater than approximately 10 m / s and more in particular greater than about 20 m / s. Apparatus according to claim 9 or 10, characterized in that it is provided with a control, in particular computer means, the control is designed to accept an echo received at a particular measurement moment which is an echo of the test signal only when an echo of the verification signal is received at a different measurement moment, and in particular when the difference between one and another measurement moment is substantially equal to the verification period. 12. Use of an apparatus according to any of claims 9 - 11, in particular for testing objects, elements, rails, vehicle parts, ship parts and / or aircraft parts and the like for defects.