TEST HEAD PROBE FOR ULTRASONIC TESTING OF WHEELSET SHAFTS WITH INTERNAL LONGITUDINAL BORE

Description

[0001] The invention relates to a probe for ultrasonic testing of wheelset axles with an internal longitudinal bore, comprising a plurality of probe carriers arranged offset from each other by an intermediate angle with respect to a central central longitudinal axis of the probe.

[0002] The axles of railway vehicles are regularly inspected for defects and inhomogeneities. This includes checking for defects in the axle material. In particular, operational cracks can develop on the outer surface of the axle. These are detected using a probe equipped with angled probe heads. This probe is mounted in an internal bore of the axle, allowing it to move linearly along the longitudinal axis of the bore and rotate freely around this axis. By utilizing the well-known angled mirror effect, inhomogeneities that are essentially perpendicular to the test surface or the outer surface of the axle can be detected. This effect is based primarily on the fact that the probe beam is reflected twice – once at the outer surface of the axle opposite the test surface and again at the inhomogeneity itself.The crack itself is reflected back towards the probe and can be detected there. The geometric offset between the beam axes of the transmitted and received probe beams in a reference direction parallel to the longitudinal axis of the inner bore allows conclusions to be drawn about the crack's location within the wheelset axle.

[0003] In the case of surface-hardened wheelset axles, crack formation does not occur on the outer surface of the axle, but rather within its internal volume, usually directly beneath the surface-hardened zone. To detect such deep-lying inhomogeneities, the so-called "tandem technique" is used according to the prior art. This technique employs two spaced-apart angle probes oriented at the same angle and in the same direction, with their acoustic axes lying in the same plane perpendicular to the test surface. One probe transmits the signal, and the other receives it. By varying the distance between the transmitting and receiving probes in a reference direction parallel to the longitudinal axis of the inner bore, inhomogeneities of varying depths can be detected, provided they are oriented perpendicular to the test surface.This is particularly necessary in areas of a wheelset axle where its outer diameter or cross-sectional area changes, such as at the basket bends in the transition region between a shaft seat and the shaft shank. These areas are hereinafter referred to as "transition regions" in the context of this invention. In such transition regions, the surface-hardened zone approximately follows the course of the cross-sectional transitions. Thus, the defects expected at the cross-sectional transitions are located at different depths. As the depth of an expected defect increases, the distance between the probes in a reference direction parallel to the longitudinal axis of the inner bore must be increased. For this purpose, the transmitting probes can be...The receiving probes within a probe holder may be arranged to be displaceable relative to each other in a direction parallel to the longitudinal axis of the inner bore, or a plurality of rigid receiving probes, equidistant from each other in this reference direction, may be provided. In both cases, it is ensured that an ultrasonic signal emitted for testing purposes and reflected by inhomogeneities at different depths actually reaches a receiving probe.

[0004] However, if the basket arch is illuminated in such transition areas, reflections occur due to the lack of parallelism between the outer surface of the wheelset axle and the longitudinal axis of the inner bore. These reflections cannot be detected by this probe configuration. Therefore, reliable detection and localization of inhomogeneities is not possible in such areas.

[0005] US 7,178,418 B2 and US 2019 / 0360976 A1 disclose probes for "pigs" or "pigs" used for the non-destructive testing of long pipelines by means of a translational method along the pipeline's longitudinal axis. Such probes comprise a multitude of probe heads distributed around their outer circumference, the relative arrangement of which is intended to enable complete coverage of the inner wall of the pipeline under test during such a translational probe movement along the pipeline's longitudinal axis. However, such testing devices are optimized for measuring wall thickness and detecting near-surface cracks in pipelines. Cracks that do not originate from a surface of the test object cannot be reliably detected. Therefore, such devices are limited to the testing of pipelines, as such deep-lying defects are not expected there.

[0006] The invention is therefore based on the technical problem of providing a generic probe head for ultrasonic testing of wheelset axles with an internal longitudinal bore, which overcomes this aforementioned disadvantage and improves the quality and reliability in the detection and localization of inhomogeneities in the area of ​​cross-sectional transitions.

[0007] This is solved according to the invention by the fact that the probe carriers are rotatably mounted simultaneously about this central longitudinal axis, wherein each probe carrier is composed of a transmitting probe and a plurality of receiving probes arranged along a longitudinal extension of the probe probe parallel to the central longitudinal axis of the wheelset axle, wherein the transmitting probe of at least one first probe carrier of the probe probe is arranged to emit a sound beam at an angle deflected in a mathematically positive sense with respect to an interface normal at the sound emission point, and the transmitting probe of at least one second probe carrier of the same probe probe is arranged to emit a sound beam at an angle deflected in a mathematically negative sense with respect to the interface normal at the sound emission point.

[0008] In the context of the invention, a "positive angle" is understood to be an angle by which the beam axis (or axis of symmetry) of the sound beam is pivoted counterclockwise with respect to the direction of the interface normal at the sound exit point of the probe. Similarly, in the context of the invention, a "negative angle" is understood to be an angle by which the beam axis of the sound beam is pivoted clockwise with respect to the direction of the interface normal at the sound exit point. In other words, these are angle measurements in radians. The probes are preferably designed as angle probes.

[0009] Such a probe head according to the invention enables the transmission of at least two sound beams with opposite directions of incidence into the same test zone of a wheelset axle without interrupting the test process to change the orientation of the probe head within the wheelset axle. By means of a rotary movement of the probe head according to the invention about the longitudinal axis of the inner bore, it is achieved that the transition area of ​​a wheelset axle is continuously covered by the sound beams of at least two probe head carriers with opposite directions of incidence during the same test process.Even if an inhomogeneity located in this transition zone lies outside the detection range of the first probe due to its excessive depth, it is still reliably detected by the second probe, which emits sound in the opposite direction to the first. In this way, the entire volume of a wheelset axle can be inspected in a single, uninterrupted pass. This not only speeds up the inspection process but also improves its quality, as removing the test fixture from the axle and then reinserting it (with its orientation reversed) eliminates a potential source of errors or inaccuracies.

[0010] The invention provides, in a particularly preferred embodiment, that the probe comprises two probe carriers arranged offset from each other by an intermediate angle of 180° with respect to the central longitudinal axis of the probe. Such an arrangement, symmetrical with respect to the central longitudinal axis of the probe, enables uniform and unbalanced rotation of the probe and facilitates the evaluation of the measurement signals acquired by the probes.

[0011] However, the invention is not limited to such a symmetrical arrangement of two probe carriers, but also extends to probe probes with any plurality of probe probes, which can be arranged with any and in particular also asymmetrical intermediate angles to each other, provided that at least two of the probe probes are set up by means of the aforementioned orientation of their probe heads to transmit sound beams with oppositely oriented directions of incidence into the same test zone of the wheelset axle.

[0012] According to one possible embodiment of the inventive concept, the probes of a probe carrier are combined into an array consisting of multiple probes. An "array" here refers to an arrangement of probes in which multiple probes are fixed to each other in a predefined relative geometric orientation by means of a holder. Such an array can enable higher testing speeds due to the rapid switching capability between multiple probe pairs.

[0013] The invention further provides that the probe head can be moved both axially along a longitudinal extension of the longitudinal bore and rotationally across the inner surface of the longitudinal bore by means of a drive device designed to generate a helical or meandering movement of the probe head about its central longitudinal axis. For this purpose, the probe head is mounted within the inner bore of a wheelset axle, allowing movement both axially along its central longitudinal axis and rotationally about the central longitudinal axis, during intended use. Such a drive device facilitates the automation of the application of the probe head according to the invention.

[0014] The present invention is explained in more detail below with reference to an exemplary embodiment and the accompanying drawings. These show: Figure 1 : schematic representation of the tandem test (state of the art); Figure 2 : schematic representation of the test with a probe head according to the invention with a sound beam deflected by a positive angle; Figure 3 : schematic representation of the test with a probe head according to the invention with a sound beam deflected by a negative angle.

[0015] The embodiment visualizes the testing of a surface-hardened wheelset axle (10) by means of a probe head (20) according to the invention inserted into the internally centered longitudinal bore (11) of the wheelset axle (10).

[0016] In Figure 1The basic principle of tandem testing, known from the prior art, is first visualized using the test of a surface-hardened wheelset axle. The test objective is to detect any inhomogeneities (51, 52) in the form of material defects that occur in the interface between a hardened outer surface layer zone (15) of the wheelset axle and an unhardened inner area of ​​the wheelset axle. This transition area between the surface layer zone (15) and the unhardened area of ​​the wheelset axle (10) is schematically visualized in the figures of the exemplary embodiment by means of a dotted line (which, of course, does not exist in this form in reality).The probe head (20) is inserted into an internal and internally centered longitudinal bore (11) of the wheelset axle (10) for the purpose of conducting the test and is mounted therein in such a way that it is both axially displaceable along its central longitudinal axis (A) and rotatable about this central longitudinal axis (A). According to the prior art known with regard to tandem testing, the probe head (20) comprises a probe head carrier (30) whose sound beam emitted by the transmitting probe head (31) can, due to this axial and rotational mounting of the probe head in the longitudinal bore (11) of the wheelset axle (10), cover the entire surface layer zone (15) and thus detect any inhomogeneities (51, 52) in the transition area to the surface layer zone (15).The sound beam emitted by the transmitting probe (31) is characterized by its acoustic axis (B), which is inclined about the angle of incidence (α) relative to the interface normal (D) at the sound exit point (C) with respect to the test object or the wheelset axle. The angle of incidence (α) is typically 35° to 55°. The sound beam undergoes two reflections: first at the interface closest to the point of incidence (i.e., the outer surface of the wheelset axle (10) opposite the sound exit point (C)) and then at the inhomogeneity (51, 52). Depending on the depth (d1, d2) of the respective inhomogeneity (51, 52), the reflected signal of the sound beam is received by one of the receiving probes (32...39) of the probe carrier (30).The maximum reception is to be expected at the receiving probe whose distance (relative to a direction parallel to the central longitudinal axis (A)) to the transmitting probe (31) has the smallest deviation from that according to the geometric relationship . a i = 2 * d i * tan α The defined so-called "jump spacing" (a1, a2) is observed. This results, for example, in the detection of inhomogeneities in the depths (di) between 10 mm and 35 mm (measured from the outer surface of the wheelset axle) at typical incident angles (α) between 35° and 55° and typical distances (ai) between the transmitting probe and the receiving probes of a probe carrier between 20 mm and 70 mm. The probe probe (20) is located on the left side of the Figure 1 in a position detecting a first inhomogeneity (51) at a first depth (d 1) as well as on the right side of the Figure 1in a position detecting a second inhomogeneity (52) at a second depth (d 2 ).

[0017] The Figures 2 and 3 visualize the inspection of a wheelset axle using a probe head according to the invention, wherein in Figure 2 the probe head (20) in a first position and in Figure 3The probe head is shown in a second position, rotated 180° about the central longitudinal axis (A) of the wheelset axle (10). The wheelset axle (10) has areas with different outer diameters; namely, a shaft seat (12) and shafts (13) adjoining it on both sides, the outer diameter of the shaft seat (12) being larger than that of a shaft (13). The outer diameter of each shaft (13) is brought into contact with the shaft seat (12) by means of a basket-shaped arch (14). In the spatial vicinity of such a basket-shaped arch (14), possible inhomogeneities (53, 54) are located, each in the transition zone between the hardened outer surface layer zone (15) and the inner area of ​​the wheelset axle (10), which is formed from the unhardened base material of the wheelset axle. The detection of inhomogeneities in this transition zone is possible with the Figure 1However, the tandem testing device shown is not possible for the following reason: although the probe head (20) can be positioned relative to the wheelset axle (10) in a direction parallel to the central longitudinal axis (A) such that the sound exit point of the transmitting angle probe head (31) is positioned in the area of ​​the axle seat (12), the acoustic axis of the sound beam, which is inclined by an angle of incidence (α) with respect to the interface normal, intersects the outer contour of the wheelset axle in the area of ​​the basket arch (14). Thus, the sound beam encounters the first reflecting interface in an area that is subject to significant cross-sectional changes and, in particular, does not exhibit parallelism to the inner surface of the longitudinal bore intended for sound coupling.

[0018] In contrast to the aforementioned prior art, the probe (20) according to the invention comprises, in addition to the first probe carrier (30), a further second probe carrier (40), wherein each probe carrier (30, 40) has a transmitting angle probe (31, 41) and a plurality of receiving angle probes (32, ... 39; 42, ... 49). All probes of each probe carrier are arranged directly adjacent to one another along a longitudinal extent of the probe carrier. In the exemplary embodiment, each probe carrier (30, 40) has eight receiving angle probes (32, ... 39; 42, ... 49). However, the invention is not limited by this, but can be implemented using probe carriers with any number of receiving probes. The second probe carrier (40) is arranged inside the probe probe (20) in a position offset by 180° around the central longitudinal axis (A) of the probe probe (20) with respect to the first probe carrier (30).The invention is not limited by this, but can also be implemented using a plurality of probe carriers with any, in particular also asymmetrical, intermediate angles to each other. According to the embodiment shown by way of example in the exemplary embodiment with two probe carriers (30, 40) offset from each other by an intermediate angle of 180° about the central longitudinal axis (A), a defined test area of ​​the wheelset axle, e.g. the area of ​​inhomogeneities (53, 54), is detected twice by the sound beam of a transmitting probe during a complete rotation of the probe probe (20) mounted in the longitudinal bore (11) of the wheelset axle (10) by 360°. Specifically, the first detection is carried out by the sound beam of the transmitting probe probe (31) of the first probe carrier (30) (as in the visualization of the probe probe (20) according to [reference]). Figure 2shown) and - after a rotation of the probe (20) by 180° about the central longitudinal axis (A) - a second time through the sound beam of the transmitting probe (41) of the second probe carrier (40) (as shown in the visualization of the probe (20) according to Figure 3 (shown).

[0019] While the acoustic axis (B 31 ) of the sound beam emitted by the transmitting probe (31) of the first probe carrier (30) - as above in the explanation of the prior art based on the Figure 1As shown, the acoustic axis (B 41) of the sound beam emitted by the transmitting probe (41) of the second probe carrier (40) is inclined by a mathematically positive first angle of incidence (α) with respect to the interface normal (D 31) at the sound exit point (C 31) relative to the wheelset axle. This means that the acoustic axis (B 41) is inclined by a mathematically negative second angle of incidence (β) with respect to the interface normal (D 41) at the sound exit point (C 41) relative to the wheelset axle. Thus, during a single complete rotation of the probe probe (20) about the central longitudinal axis (A), sound beams from two opposite directions are emitted into the area of ​​the wheelset axle (10) to be tested.

[0020] At the in Figure 2In the depicted view, the probe head (20) is in such a relative first position with respect to the wheelset shaft (10) that the first probe head carrier (30) with the first angle of incidence (α) deflected in the mathematically positive sense is closest to the area of ​​the wheelset shaft (10) to be tested and the inhomogeneities (53, 54) are subject to an incidence at the first angle of incidence (α).

[0021] At the in Figure 3In the depicted view, the probe head (20) is rotated by 180° around the central longitudinal axis (A) of the wheelset shaft (10) compared to the aforementioned first position and is in such a relative second position with respect to the wheelset shaft (10) that the second probe head carrier (40) with the second angle of incidence (β) deflected in the mathematically negative sense is closest to the area of ​​the wheelset shaft (10) to be tested and the inhomogeneities (53, 54) are subject to an incidence at the second angle of incidence (β).

[0022] The relative arrangement of the transmitting angle probe (41) with respect to the receiving angle probes (42...49) is inverse or mirror image of the relative arrangement of the transmitting angle probe (31) and receiving angle probes (32...39) of the first probe carrier (30) in the second probe carrier (40). While in the first probe carrier (30) the transmitting probe (31) is positioned in front of the receiving probes (32...39) with respect to one longitudinal direction of the probe carrier, this arrangement is diametrically opposite in the second probe carrier with respect to the same longitudinal direction; i.e., the transmitting probe (41) is positioned in the rearmost position after the receiving probes (42...49) with respect to the longitudinal direction of the probe carrier. This is necessary so that the sound beam of the transmitting probe (41) is directed according to the aforementioned Figure 1The basic principle of tandem testing is explained when reflection occurs at an outer surface of the wheelset axle acting as an interface and meets the arrangement of the receiving probes (42...49). Reference symbol list:

[0023] 10 Wheelset axle 11 Longitudinal bore 12 Shaft seat 13 Shaft 14 Basket bend 15 Edge layer zone A Central longitudinal axis of the wheelset axle 20 Probe 30 First probe carrier 31 Transmitting angle probe of the first probe carrier α First angle of incidence B, B 31 , B 41 Acoustic axis of the sound beam C, C 31 , C 41 Sound exit point D, D 31 , D 41 Interface normal at the sound exit point 32...39 Receiving angle probes of the first probe carrier 40 Second probe carrier 41 Transmitting angle probe of the second probe carrier β Second angle of incidence 42...49 Receiving angle probes of the second probe carrier 51...54 Inhomogeneity d 1 . d 2 Depth of an inhomogeneity a 1 , a 2 Jump distance between transmitting and receiving probe

Claims

1. Test head probe (20) for ultrasonic testing of wheel set shafts (10) with an internal longitudinal hole (11), comprising a plurality of test head carriers (30, 40) which are arranged offset by an intermediate angle with respect to a longitudinal center axis (A) of the test head probe (20), characterized in that the test head carriers (30, 40) are supported so as to be able to be rotated simultaneously about this longitudinal center axis (A), wherein each test head carrier (30, 40) is constructed from one transmitting test head (31, 41) and a plurality of receiving test heads (32...39; 42...49) which are arranged along a longitudinal extent of the test head probe (20) which is parallel with the longitudinal center axis (A), wherein the transmitting test head (31) of at least a first test head carrier (30) of the test head probe (20) is configured for a sound output of a sound beam at an angle (α) which is deflected with respect to an interface normal (D31) at the noise output location (C31) in the mathematically positive sense and the transmitting test head (41) of at least a second test head carrier (40) of the same test head probe (20) is configured for sound output of a sound beam at an angle (β) which is deflected with respect to the interface normal (D41) at the noise output location (C41) in the mathematically negative sense.

2. Test head probe according to patent claim 1, characterized in that the test head probe (20) comprises two test head carriers (30, 40) which are arranged offset relative to each other at an intermediate angle of 180° with respect to the longitudinal center axis (A) of the test head probe (20).

3. Test head probe according to patent claim 1 or 2, characterized in that the test heads of a test head carrier are combined to form an array which is constructed from a plurality of test heads.