Method for ultrasonically inspecting an aluminothermically welded rail joint

Abstract

The invention relates to non-destructive ultrasonic testing of flat-bottom rails, laid on track, and can be used for detection of defects in tips of the rail foot on aluminothermic welded joints, performed by the intermediate casting method. During the ultrasonic testing of aluminothermic welded joints, at least two zones for ultrasonic testing were determined with selecting one of at least two zones on the weld bead (reinforcing bead) from the lateral surface of the tip of the rail foot. At least two specific zones are grinded on the weld collar (reinforcing collar) with creation of at least two flat areas, which are able to ensure acoustic contact. The ultrasonic transducer is placed on every flat area of the collar, which is connected to at least one ultrasonic flaw detector. Ultrasonic testing of weld is performed using at least one flaw detector Delta-method or echo-method. As a result of the invention implementation, there is no any blind zone in the base of the rail welded joint. The described invention ensures higher accuracy in detection of welds defects within the tips of the rail foot area. 2 z.p. f-ly, 8 il.

Claims

1. A method of ultrasonic testing of aluminothermic welded joints on rails including stages as follows: determination of at least two zones for ultrasonic testing with selecting one of at least two zones on the weld collar (reinforcing collar) from the lateral surface of the tips of the rail foot; grinding of the specific areas on the collar (reinforcing collar) with creation of flat areas that enable acoustic contact; placement of ultrasonic transducer on every flat area on the collar, which is connected to at least one ultrasonic flaw detector; and ultrasonic testing of weld using at least one flaw detector via Delta-method or echo-method.

2. The method of claim 1, in which at least one another zone of ultrasonic testing is selected from the following areas during determination of ultrasonic testing zones: lateral surface of the tip of the rail foot, upper surface of the tip of the rail foot.

3. The method of claim 1, in which stages of ultrasonic flaw detector installation and welds ultrasonic testing are performed using at least one flaw detector for every specific zone in sequence.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1, 2 show the scanning method as per prior art.

(2) FIG. 3 shows the schematic diagram for implementation of the described method during the application of ultrasonic testing method from the lateral surface of the tip of the rail foot near the aluminothermic joint.

(3) FIG. 4 shows the schematic diagram for implementation of the described method during application of ultrasonic testing method from the lateral surface of the tip of the rail foot near the aluminothermic joint (side view).

(4) FIG. 5 shows the schematic diagram for implementation of the described method during the application of ultrasonic testing method from the upper surface of the tip of the rail foot near the aluminothermic joint.

(5) FIG. 6 shows the schematic diagram for different embodiment of the described method during the application of ultrasonic testing method from the upper surface of the tip of the rail foot near the aluminothermic joint.

(6) FIG. 7 shows the schematic diagram for implementation of the described method during application of ultrasonic testing method from the lateral surface of the tip of the rail foot and from its upper surface near the aluminothermic joint.

(7) FIG. 8 shows the schematic diagram for implementation of the described method during application of ultrasonic testing method from the lateral surface of the tip of the rail foot and from its upper surface near the aluminothermic joint (side view).

EMBODIMENTS OF INVENTION

(8) FIG. 3 shows the schematic illustration of embodiment of the described method for ultrasonic testing of an aluminothermic weld. The method can be implemented using at least one flaw detector (not shown) and at least one ultrasonic sensor (12), connected to the above-mentioned flaw detector. Avikon-02r UDS2-112 or UDS2-RDM-33, operating per echo- or Delta-methods, can be used as a flaw detector. According to GOST 55725-2013, the probes like RS PEP P112-2,5 and PEP P121-2,5 can be used as ultrasonic sensors.

(9) As it will be clear to an expert, the illustrative example on FIG. 3 shows the simplified non-limiting embodiment, which is implemented from the lateral surface of the tip of the rail foot via one flaw detector and one ultrasonic sensor (12) RS PEP P112-2,5. The number of the sensors used depends on the selected zones and scanning patterns. As it is shown on FIG. 3.4, at least one ultrasonic sensor (12), connected to one flaw detector (not shown), is sufficient for implementation of the described method. If only one ultrasonic sensor (12) is applied, the ultrasonic testing is performed using one flaw detector in sequence for every specific zone.

(10) FIG. 5 shows non-limiting embodiment, in case of which the upper surface of the tip of the rail foot is selected as at least half of zone for ultrasonic testing. Ultrasonic testing can be performed in sequence using one flaw detector (not shown) and one ultrasonic sensor (12) RS PEP P112-2,5.

(11) In case of another invention embodiment, shown on FIG. 6, two ultrasonic sensors (12) PEP P121-2,5 with different angles of entry on two corresponding pads (13) can be installed on the upper surface of the tip of the rail foot (at least, a half of the zone for ultrasonic testing).

(12) FIGS. 7 and 8 show the schematic diagram for another embodiment of the described method during the application of ultrasonic testing method from lateral surface of the tip of the rail foot and from upper surface of the top of the rail foot near the aluminothermic joint (side view). Besides, the testing is performed via the Delta-method using two sensors (12), connected to one flaw detector via a separate circuit: one piezoelectric transducer-transmitter (14) and another piezoelectric transducer-receiver (17).

INDUSTRIAL APPLICABILITY

(13) Description of implementation of described method for ultrasonic testing of the aluminothermic welded rail joint with reference to FIGS. 3, 4, 5, 6, 7, 8 is given below.

(14) The method begins at a stage of determining at least two zones for ultrasonic testing. The determination is performed depending on sizes of the touch surface of ultrasonic sensors, selected scanning pattern of the blind zone, accessibility for preparation of a pad by grinding. Moreover, one of at least two zones is selected on welded joint from the lateral surface of the tip of the rail foot (11) (FIG. 3-4, FIG. 7-8).

(15) At least one different ultrasonic inspection zone is selected, for example, on the upper surface of the tip of the rail foot on the weld collar (10), as shown on FIG. 5, 6, 7.

(16) Ultrasonic testing zones are defined based on the following principle: scanning of the weld section center (blind zone) with the transducer's acoustic axis using direct beam.

(17) Then, at least two determined zones are ground with creation of minimum two appropriate pads (13) ((15), (16)) that ensure acoustic coupling of ultrasonic sensors (12) ((14), (17)). Grinding can be performed by any available means, such as angle grinder, operating from the mains or from an accumulator battery.

(18) The ultrasonic sensor (12) ((14) (17)) is installed on each flat area (13) ((15), (16)), which is connected to at least one ultrasonic flaw detector, and the section center (blind zone) of rails (11) weld is scanned.

(19) In the general case, shown on FIG. 3, 4, one of at least two zones is selected on the weld bead (10) (reinforcing bead) from the lateral surface of the tip of the rail foot. Then, the area is grinded, in order to form a flat surface (13) for ultrasonic sensor (12), and the weld is ultrasonically tested using at least one echo flaw detector.

(20) In accordance with non-limiting embodiment, shown on FIG. 5, another area of at least two zones is selected on the upper surface of the tip of the rail foot at the bead (10). Then, the area is ground, in order to form a flat surface (13) for ultrasonic sensor (12), and the weld is ultrasonically tested using at least one echo flaw detector. Upon the completion of the above stages on one of the tops of the rail foot, similar stages can be completed on the opposite tip of the rail foot.

(21) According to another non-limiting embodiment, shown on FIG. 6, two zones on the upper surface of the tip of the rail foot (11) can be selected as at least one another zone. Moreover, flat areas (13) are arranged symmetrically at an angle of 40-50 to the surface on the edges of the tip of the rail foot (10). For example, for the welding gap of 50 mm, the angle is 40; for the gap of 75 mm, the angle is 50. The entry angle is defined graphically at scale provided that center of the blind zone is scanned with the transducer acoustic axis. If only one ultrasonic sensor (12) is used, is installed on every prepared pad (13) in parallel or in series for further ultrasonic testing of weld using at least one pulse echo flaw detector, mentioned above. Upon the completion of the above stages on one of the tips of the rail foot, similar stages can be completed on the opposite tip of the rail foot.

(22) It is possible to apply embodiment, when an ultrasonic test is firstly performed from the lateral surface of the tip of the rail foot on the right and on the left (on right and left tips of the rail foot (11)), and then at least one different zone is ultrasonically tested. Thus, the procedure for performing ultrasonic testing in certain areas is not a limiting condition.

(23) Availability of an echo signal with the amplitude, exceeding the rejectable level, will be regarded as an indication of the detected defect. Ultrasonic testing is performed, for example, by measuring the amplitude of received signals for each ultrasonic transducer, receiving the reflected signal at current moment. The time position of received signals, i.e. time frame between transmitted and received signals is measured. The defect spatial position is calculated using the known scanning pattern, the time position of received signals and a propagation speed of ultrasonic signal in rail. Results of all scans are subject to evaluation and decision with regard to the rail weld quality will be made. For this purpose, the location and amplitudes of received signals are cross checked, in order to create a basis for quality conclusions.

(24) If only one ultrasonic sensor (12) is used, stages of installation, fixation, and ultrasonic inspection are initially performed for one specific ultrasonic testing zone, and then for at least one another specific ultrasonic inspection zone in sequence. Subsequently, the method can be completed or repeated for the same or other zones.

(25) Illustrative example on FIG. 7, 8 shows that the scanning is performed using Delta-method that involves two transducers (12), connected via a separate connection circuit to one flaw detector (one piezoelectric transducer-transmitter (14) and another piezoelectric transducer-receiver (17)). A flat area (15) shall be arranged for transmitter (14) at the lateral surface of the tip of the rail foot (11), and another pad (16) shall be arranged for receiver (17) at the upper surface of the tip of the rail foot (11).

(26) The flat area (15) is arranged by a grinding the lateral surface of the tip of the rail foot (11) along the entire length of the collar (10). the flat area (16) is arranged for receiver (17) by grinding the upper surface of the top of the rail foot in the center of the collar (10) with a width of 20-40 mm. Testing procedure (FIG. 8)a transmitter (14) is placed into position (151) on the flat area (15), then, using receiver, (17) scan from the foot edge to the rail web by moving the receiver (17) along flat area (16). Then, transmitter (14) is shifted into position (152), and receiver (17) is used for scanning from web to the foot edge by moving the receiver (17) along flat area (16). Then, the transmitter (14) is shifted into position (153), and receiver (17) is used for scanning from web to the foot edge by moving receiver (17) along flat area (16). It should be noted that the illustrative example on FIG. 8 shows 3 positions (151), (152), (153) of transmitter (14), however, in order to implement the described method, a larger or smaller number of positions of transmitter (14) on flat area (15) can also be used, depending on the collar (10) width and a selected model of ultrasonic sensor (12) (transmitter (14)). The above scanning operations shall be repeated, until the transmitter (14) moves from one edge of the flat area (15) to its another edge (15) across the collar (10). Upon completion of scanning operations of one (for example, left) flat area, the same operations are conducted on another flat area (for example, right). A defect (18) detection will be proved by the receiver is fixed the signal diffracted on the defect (diffraction effect will take place when the wave is on the defect).

(27) As a result of implementation of the claimed method, there is no any blind zone in the base of rail's welded joint. The method ensures higher accuracy of the weld defects detection in the tips of the rail foot area (11).