Wire rope flaw inspection device

Abstract

The invention relates to an inspection device (100) for the magneto-inductive inspection of a tendon or cable (T), comprising a frame unit (102) configured to receive the tendon or cable (T) in a reception space (102a), at least one annular sensor unit (104) configured to surround the tendon or cable (T), at least two magnet units (106) configured to be fixed to the frame unit (102), and at least one distance maintaining element (150) configured to support the frame unit (102) on the surface of the tendon or cable (T), wherein the frame unit (102) is a U-shaped frame unit, wherein the at least one annular sensor unit (104) is configured to be releasably fixed to the frame unit (102), and wherein the at least two magnet units (106) are configured to be releasably fixed to the frame unit (102) within a circumferential portion extending over at most 150°.

Description

[0001] Inspection Device

[0002] Description

[0003] The invention relates to an inspection device for the magneto-inductive inspection of a tendon or cable, for example an external tendon in a post-tensioned building structure.

[0004] Inspection devices for the magneto-inductive inspection of tendons or cables as such are known in the art. For example, the inspection device R140 of Ropesys GmbH has a frame unit configured to receive the tendon or cable in a reception space, at least one annular sensor unit configured to surround the tendon or cable, at least two magnet units configured to be fixed to the frame unit, and at least one distance maintaining element attached to each longitudinal end of the frame unit, the distance maintaining element being configured to support the frame unit on the surface of the tendon or cable.

[0005] However, the R140 inspection device is not suited for use in confined spaces as they are, for example, found when inspecting external tendons in post-tensioned building structures, e.g. in bridge girders or the like, where the tendons are arranged in close vicinity to each other and the bottom and side walls of the building structure.

[0006] Therefore, it is the object of the invention to provide an inspection device which can be used for the magneto-inductive inspection of tendons or cables even under confined spatial conditions, e.g. when inspecting an external tendon in a posttensioned building structure.

[0007] According to the invention this object is achieved by an inspection device for the magneto-inductive inspection of a tendon or cable comprising: a frame unit configured to receive the tendon or cable in a reception space, at least one annular sensor unit configured to surround the tendon or cable, at least two magnet units configured to be fixed to the frame unit, and at least one distance maintaining element attached to each longitudinal end of the frame unit, the distance maintaining element being configured to support the frame unit on the surface of the tendon or cable, wherein the frame unit is a U-shaped frame unit, the reception space of which is formed between the side legs of the U-shape, wherein the at least one annular sensor unit is configured to be releasably fixed to the frame unit, and wherein the at least two magnet units configured to be releasably fixed to the frame unit within a circumferential portion extending over at most 150°, preferably over at most 120°.

[0008] The U-shape of the frame unit facilitates positioning the inspection device on the tendon or cable. It only needs to be placed on the tendon or cable from above. In particular, it is- due to the U-shape - not necessary to attach two half-shells to each other, which would be difficult, if not impossible, in the confined spatial conditions in the building structures in question. In addition, the inspection device according to the invention has a modular structure due to the releasable fixing of both the at least one sensor unit and the magnet units to the frame unit and can therefore be mounted on the tendon or cable component after component. For example, the at least one sensor unit can be placed on the tendon or cable first. Then the frame unit can be placed over the at least one sensor unit, and the at least one sensor unit can be attached to the frame unit. Finally, the magnet units can be attached to the frame unit one after the other. Since they are only arranged in an angular range of at most 150°, preferably at most 120°, the magnet units can also be attached to the frame unit in a straight-forward manner and exclusively from above. As can be easily understood, all this work can also be carried out without difficulty in the confined spatial conditions that exist in the building structures mentioned. With regard to the angular range indicated above, it should be noted that this angular range is measured between the center planes of the two or the two magnet units located furthest apart.

[0009] In order to reduce the weight of the frame unit and / or to provide a frame unit having a simple design, the U-shaped frame unit can include two end plates and at least three longitudinal strut elements connecting the end plates, one of the strut elements preferably being located at or in the vicinity of the base leg of the U- shape, and two of the strut elements, further preferably, being located at or in the vicinity of each of the free ends of the side legs of the U-shape.

[0010] Preferably, a distance between the side legs of the U-shape amounts to at least 140mm. This allows to inspect also the tendons or cables of, for example, larger post-tensioned building structures, e.g. bridges.

[0011] As it is known as such from the prior art, also in the inspection device according to the present invention the sensor unit can comprise at least two sensor sub-units releasably fixable to each other so as to allow their assembling around and disassembling from the tendon or cable, at least one of the sensor sub-units preferably having a sensor sub-unit housing and a sensor array. Thus, the sensor sub-unit housing may serve as an adapter allowing to connect different types of sensor arrays to the frame unit. For example, the sensor array may have at least one inductive coil sensor and / or at least one Hall effect sensor, e.g. combined in respective sensor arrays. Hall-effect sensors and coil sensors can be used to detect Local Faults (LF) such as wire breaks or corrosion pits, while Hall-effect sensors can be further used to identify Loss of Metallic Area (LMA) due to corrosion or wear.

[0012] Further it is suggested that the sensor unit can be configured to be releasably fixed to the strut element located at or in the vicinity of the base leg of the U- shape, preferably in a central portion thereof. For example, the releasable fixation of the sensor unit to the frame unit can be designed using a guide bearing rail unit having two cooperating components, one component, e.g. the guide carriage, being attached to the sensor unit, while the other, e.g. the guide rail, is attached to the strut element, and a biased, for example spring-biased, pin element attached to the strut element and insertable into a corresponding hole provided in the sensor unit or an element attached thereto, e.g. the sensor unit-side plain bearing rail component.

[0013] For analogous reasons, at least one of the magnet units can include a housing and a magnet, the housing preferably having a handle at each of its longitudinal ends. Preferably permanent magnet units and permanent magnets are used according to the invention in order to avoid disturbances of the inspecting magnet field caused by the electromagnetic fields generated by an alternating current flowing through electric supply lines leading to electromagnets. Furthermore, such electric supply lines would render the handling of the inspection device more difficult, in particular when drawing the inspection device along the tendon or cable for inspecting same.

[0014] In any case, it is suggested that the number and the dimensions of the magnets are chosen such that together they are strong enough to completely magnetize the entire metallic cross-section of a tendon or cable fitting into the reception space to a minimum of 1.9 Tesla according to DIN EN 12927.

[0015] For example, the permanent magnets can be rare earth magnets, for example Neodymium magnets.

[0016] Furthermore, the length of the magnets can amount to at least five times the distance of the side legs of the U-shape, while their cross-sectional area could amount to at least 5.000mm2. If the inspection device is designed for inspecting tendons or cables having a diameter of 140mm, the magnets could, for example, have a length of at least 725mm, and a rectangular cross-section of about 60mm x 100mm.

[0017] In order to enable a single operating person to attach one of the magnet units at the frame unit, one of the magnet unit housing and the frame unit can include at its one longitudinal end a centering pin configured to cooperate with a mating centering recess allocated to the other of the frame unit and the magnet unit housing. As soon as the operating person has inserted the centering pin into the mating centering recess, the magnet unit is held in the two spatial directions orthogonal to the axis of the centering pin. In this situation, the operating person can release with his / her one hand the handle close to the centering pin, and operate with this hand a connecting element, e.g. a quick connector having a centering function, in order to completely fix this end of the magnet unit to the frame unit, while s / he still holds the magnet unit with his / her other hand.

[0018] In order avoid that the operating person has to excessively act against the magnetic forces exerted between the magnet and the steel of the tendon or cable, it is suggested that the centering recess can be provided in an element pivotably connected to the frame unit, the pivoting axis preferably extending orthogonal to the longitudinal direction of the frame unit, the pivotable element preferably being configured to be fixed at a predetermined angle of preferably less than 45°, more preferably of about 30°. This inclination, on the one side, ensures a sufficient distance of the magnet from the tendon or cable, while, on the other side, allowing to handle the magnet unit taking the confined spatial conditions into account. In order to fix the pivotable element at the predetermined angle, for example, a temporary holder element can be used, e.g. a wedge made from plastic material.

[0019] In order to provide a predetermined relative positioning of the magnet unit and the frame unit also at the other end of the magnet unit, a wedge-shaped element can be provided at the other longitudinal end of the magnet unit housing or the frame unit, while a receiving element having a tapering recess configured to receive the wedge-shaped element is provided at the frame unit or the other longitudinal end of the magnet unit housing.

[0020] In order to reliably maintain this relative positioning the wedge-shaped element and the receiving element can have communicating bores configured to receive a securing pin. The use of this securing pin secures is a safety measure, as the afore-mentioned magnet forces should anyway attract the magnet towards the tendon or cable.

[0021] Furthermore, at least two distance maintaining elements, preferably at least three distance maintaining elements, can be attached to each longitudinal end of the frame unit. While two distance maintaining elements are sufficient in order to precisely locate the frame unit relative to the tendon or cable, a number of three distance maintaining elements results in a better guidance of the inspection device when drawn along the tendon or cable.

[0022] Generally the distance maintaining element could be a skid, in particular a skid made from a plastic material, e.g. Polytetrafluoroethylene (PTFE). In order to reduce friction between the inspection device and the tendon or cable when drawing the inspection device along the tendon or cable, it is, however, advantageous, if at least one of the distance maintaining elements is a roller.

[0023] In order facilitate the correct positioning of the inspection device relative to the tendon or cable, in particular to correct the positioning in a situation where the inspection device is already located at the tendon or cable, at least one distance maintaining element, preferably roller, can be configured to allow in situ and preferably step-less adjustment of its position relative to the frame unit. Here the term “in situ” especially means that the distance maintaining element, preferably roller, needs not to be disassembled from the frame unit in order to insert distance plates or the like, but can stay where it is, i.e. in situ. The in situ adjustability can be put into practice, for example, by the distance maintaining element, preferably roller, being attached to a sliding element sliding inside a cage element attached to the frame unit, and further providing a spindle drive mechanism, in particular a self-locking spindle drive mechanism, cooperating with the cage element and the sliding element.

[0024] As was already indicated during the afore discussion of the invention, it is preferred that the releasable fixation of the at least one sensor unit and / or the at least two magnet units can include tool-free assembling and disassembling of the at least one sensor unit and / or the at least two magnet units to and from the frame unit, thus allowing the assembling and disassembling of the inspection device according to the present invention by one single operating person. To this end, it is further advantageous if each of the components of the inspection device weighs at most 25kg, preferably at most 22,5kg, more preferably at most 20kg.

[0025] In particular, the inspection device according to the present invention allows its use, if the distance of neighbor tendons or cables amounts to at least 222mm and the clearance of the tendon or cable from the floor or wall of the building structure amounts to at least 75mm.

[0026] In the following the invention will be explained in more detail referring to an embodiment shown in the drawings:

[0027] Figure 1 shows a perspective view of an inspection device according to the invention in a state mounted on a tendon to be inspected;

[0028] Figure 2 shows a perspective exploded view of the inspection device of Figure 1 ;

[0029] Figure 3 shows an enlarged side view illustrating the connection of a magnet unit of the inspection device according to the invention to the frame unit thereof;

[0030] Figure 4 shows a front view of the frame unit of the inspection device according to the invention; and

[0031] Figure 5 shows an enlarged perspective view of one end of the frame unit of the inspection device according to the invention.

[0032] In Figure 1 an inspection device according to the present invention is generally denoted by reference numeral 100. According to the invention, the inspection device 100 is configured for the magneto-inductive inspection of an external tendon T in a post-tensioning building structure (not shown).

[0033] As can be seen from Figures 1 and 2, the inspection device 100 has a modular design. In particular, the inspection device 100 comprises a U-shaped frame unit 102 having a reception space 102a configured to receive the tendon T, as well as an annular sensor unit 104 configured to surround the tendon T and two permanent magnet units 106 configured to be fixed to the frame unit 102 and to magnetize the metallic cross-section of a portion of the tendon T received in the reception space 102a. According to the invention, the sensor unit 104 and the magnet units 106 can be releasably fixed to the frame unit 102 without using tools.

[0034] According to Figure 2, the frame unit 102 comprises two U-shaped end plates 108 connected to each other by three strut elements 110a, 110b, 110c. While two 110b, 110c of the strut elements are located in the vicinity of a respective the free end of a side leg 108a of the U-shaped end plates 108, the third 110a of the strut elements is located at the base leg 108b of the U-shaped end plates 108. In this way, a light-weight, but nevertheless robust frame unit 102 is obtained.

[0035] Figure 2 further shows that the annular sensor unit 104 comprises two arc-shaped sensor sub-units 104a and 104b, each including a sensor sub-unit housing 112 and the actual sensor array 114 connected thereto.

[0036] When assembling the inspection device 100, a first assembling step consists of placing the two arc-shaped sensor sub-units 104a, 104b around the tendon T and releasably fixing them to each other using connecting elements 116.

[0037] In a second assembling step, the frame unit 102 is mounted to the tendon T. As can be seen from Figure 1 , a wheel drive 118 including a plurality of rollers units 120 at both ends of the frame unit 102 is configured to support the frame unit 102 at a predetermined distance from the tendon T. In the next assembling step, the sensor unit 104 is connected to the frame unit 102, in particular the strut element 110a thereof, using a guide bearing rail unit 122. A guide carriage 122a of the guide bearing rail unit 122 is attached to the sensor unit 104, while the guide rail 122b is attached to the strut element 110a. The afore-mentioned predetermined distance is chosen such that the guide carriage 122a and the guide rail 122b can be slid onto one another when the roller units 120 are supported by the tendon T.

[0038] Furthermore, a spring-biased pin element 122c is attached to the strut element 110a. This pin element 122c can be inserted into a corresponding hole (not shown) provided in the sensor unit 104 for securing the sensor unit 104 to the frame unit 102.

[0039] During the final assembling steps, the two magnet units 106 are connected to the frame unit 102. Like the sensor sub-units 104a, 104b, each magnet unit 106 includes a housing 124 carrying the actual permanent magnet 126. As the permanent magnet 126 are the heaviest parts of the entire inspection device 100, the housing 124 includes two handles 128, one at each longitudinal end of the housing 124, thus allowing the operating person to easily grip the respective magnet unit 106 and to approach it to the frame unit 102 without further assistance from a second operating person.

[0040] For releasably fixing the magnet unit 106 to the frame unit 102, both are equipped with respective cooperating components of a quick-release connector unit 130, the details of which can be best seen from Figure 3.

[0041] The quick-release connector unit 130 includes a centering pin 132 allocated to the magnet unit housing 124 and configured to cooperate with a mating centering recess 134 allocated to the frame unit 102. As soon as the centering pin 132 is inserted into the centering recess 134, the magnet unit 106 is held in the two spatial directions orthogonal to the axis CP of the centering pin 132. In this situation, the operating person can release with his / her one hand the handle 128 close to the centering pin 132, while still holding the permanent magnet unit 106 with his / her other hand and establish the connection by pivoting an operating lever 136 of the quick-release connector unit 130 shown in Figures 1 and 2.

[0042] In order avoid that the operating person has to excessively act against the magnetic forces exerted between the magnet unit 106 and the steel of the tendon T, the centering recess 134 is provided in an element 138 pivotably connected to the frame unit 102 around an axis PE extending substantially orthogonal to both the axis CP of the centering pin 132 and the longitudinal axis L of the frame unit 102, which in turn extends substantially parallel to the axis A of the tendon T (see Figure 1 ) when the frame unit 102 is mounted on the tendon T. Furthermore, a wedge element 140 can be used in order to block pivoting element 138 in an inclined position shown in Figure 3. This inclined position ensures a sufficient distance of the magnet unit 106 from the tendon T.

[0043] As soon as the quick-release connector unit 130 is closed, the wedge element 140 can be removed, and the other end of the magnet unit 106 can be pivoted down towards the frame unit 102. As can be seen from Figures 1 and 2, a wedge- shaped centering element 142 is provided at the other longitudinal end of the magnet unit housing 124, while a corresponding receiving element 144 having a tapering recess configured to receive the wedge-shaped centering element 142 is provided at the frame unit 102. As soon as the centering element 142 is inserted in the receiving recess 144, the relative position of these two components 142, 144 can be secured using a securing pin 146, which can be inserted in communicating bores 142a, 144a of the centering element 142 and the receiving recess 144.

[0044] At this point, it should be again emphasized that all afore-described steps for assembling the inspection device 100 can be carried out without using any tools, and the same is true as well for the disassembling of the inspection device 100.

[0045] As can be seen from Figure 4, the magnet units 106 are releasably fixed to the frame unit 102 within a circumferential portion extending over an angle [3 amounting to at most 150° relative to the longitudinal axis L of the frame unit 102. This allows the inspection of a tendon T, even if the neighboring tendons T’ and T” are located in close vicinity to the presently inspected tendon T.

[0046] Finally, Figure 5 shows the wheel drive 118 and some of the roller units 120 in more detail.

[0047] Each of the roller units 120 includes a roller 150 rotatably mounted to a sliding element 152 slidingly supported in a cage element 154 fixed to the frame unit 102, in particular one of the end plates 108 thereof. Furthermore, a spindle drive mechanism 156 can be provided which, by cooperation with the cage element 154 and the sliding element 152, allows to precisely adjust the position of the roller 150 relative to the surface of the tendon T (see Figure 1 ).

[0048] It should be noted that even if a tool is used for operating the spindle drive mechanism 156, this doesn’t jeopardize the tool-free assembling and disassembling of the inspection device 100 as such, as a once-finished adjustment of the rollers 150 can be used for a plurality of, preferably all, tendons T of a specific building structure, as these tendons usually all have the same outer diameter.

Claims

Claims1 . Inspection device (100) for the magneto-inductive inspection of a tendon or cable, for example an external tendon (T) in a post-tensioned building structure, the tendon or cable (T) not being part of the inspection device, the inspection device (100) comprising:• a frame unit (102) configured to receive the tendon or cable (T) in a reception space (102a),• at least one annular sensor unit (104) configured to surround the tendon or cable (T),• at least two magnet units (106) configured to be fixed to the frame unit (102), and• at least one distance maintaining element (150) attached to each longitudinal end of the frame unit (102), the distance maintaining element (150) being configured to support the frame unit (102) on the surface of the tendon or cable (T), wherein the frame unit (102) is a U-shaped frame unit, the reception space (102a) of which is formed between the side legs (108a) of the U- shape, wherein the at least one annular sensor unit (104) is configured to be releasably fixed to the frame unit (102), and wherein the at least two magnet units (106) are configured to be releasably fixed to the frame unit (102) within a circumferential portion extending over at most 150°.

2. The inspection device according to claim 1 , wherein the U-shaped frame unit (102) includes two end plates (108) and at least three longitudinal strut elements (110a, 110b, 110c) connecting the end plates (108), wherein, preferably, one of the strut elements (110a) is located at or in the vicinity of the base leg (108b) of the U-shape, andwherein, further preferably, two (110b, 110c) of the strut elements are located at or in the vicinity of each of the free ends of the side legs (108a) of the U-shape.

3. The inspection device according to claim 1 or 2, wherein the sensor unit (104) comprises at least two sensor subunits (104a, 104b) releasably fixable to each other so as to allow their assembling around and disassembling from the tendon or cable (T).

4. The inspection device according to claim 3, wherein at least one of the sensor sub-units (104a, 104b) has a sensor sub-unit housing (112) and a sensor array (114).

5. The inspection device according to any of claims 1 to 4, wherein the sensor unit (104) is configured to be releasably fixed to the strut element (110a) located at or in the vicinity of the base leg (108b) of the U-shape, preferably in a central portion thereof.

6. The inspection device according to any of claims 1 to 5, wherein at least one of the magnet units (106) includes a housing (124) and a magnet (126), the housing (124) preferably having a handle (128) at each of its longitudinal ends.

7. The inspection device according to any of claims 1 to 6, wherein at least one, preferably all, of the magnet units (106) is a permanent magnet unit, preferably including a permanent magnet (126).

8. The inspection device according to any of claims 1 to 7, wherein the number and the dimensions of the magnets (126) are chosen such that together they are strong enough to completely magnetize the entire metallic cross-section of a tendon or cable (T) received in the reception space (102a), preferably to at least 1.9 Tesla.

9. The inspection device according to any of claims 1 to 8, wherein one of the magnet unit housing (124) and the frame unit (102) includes at its one longitudinal end a centering pin (132) configured to cooperate with a mating centering recess (134) allocated to the other of the frame unit (102) and the magnet unit housing (124).

10. The inspection device according to claim 9, wherein the centering recess (134) is provided in an element (138) pivotably connected to the frame unit (102), the pivoting axis (PE) preferably extending orthogonal to the longitudinal direction (L) of the frame unit (102), the pivotable element (138) preferably being configured to be fixed at a predetermined angle of preferably less than 45°, more preferably of about 30°.11 . The inspection device according to any of claims 1 to 10, wherein a wedge-shaped element (142) is provided at the other longitudinal end of the magnet unit housing (124) or the frame unit (102), while a receiving element (144) having a tapering recess configured to receive the wedge-shaped element (142) is provided at the frame unit (102) or the other longitudinal end of the magnet unit housing (124).

12. The inspection device according to claim 11 , wherein the wedge-shaped element (142) and the receiving element (144) have communicating bores (142a, 144a) configured to receive a securing pin (146).

13. The inspection device according to any of claims 1 to 12, wherein at least two distance maintaining elements (150), preferably at least three distance maintaining elements, are attached to each longitudinal end of the frame unit (102).

14. The inspection device according to any of claims 1 to 13, wherein at least one of the distance maintaining elements (150) is a roller.

15. The inspection device according to any of claims 1 to 14, wherein at least one distance maintaining element (150), preferably roller, is configured to allow in situ and preferably step-less adjustment of its position relative to the frame unit (102).

16. The inspection device according to any of claims 1 to 15, wherein the releasable fixation of the at least one sensor unit (104) and / or the at least two magnet units (106) includes tool-free assembling and disassembling of the at least one sensor unit (104) and / or the at least two magnet units (106) to and from the frame unit (102).

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