JP2012098193A - Self-traveling flaw detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a crack inspection of a weld zone between a trough rib and a deck while self-traveling on the lower surface of a steel floor system with its retained thereto by a magnetic force regarding a self-traveling flaw detector.SOLUTION: A flaw inspection robot 14 self-travels on the lower surface of the steel floor system while being retained by an attraction force of a magnet. The self-traveling robot 14 is provided with an ultrasonic flaw detecting part 28 to adjust a position in a car width direction by a rack-and-pinion and sliding mechanisms. The ultrasonic flaw detecting part 28 includes an ultrasonic flaw detecting probe 30, a skiing-like sled 34, and springs 40. The ultrasonic flaw detecting probe 30 and the sled 34 can follow the attitude of a fine sliding of a detecting object surface, and the springs 40 are provided at the moving-directional front/rear and retain the plane contact with the detecting object surface even to either-directional movement. A tip portion 34-1 of the skiing-like sled can climb over a projection such as a weld bead and the like.

Description

  The present invention relates to a self-propelled flaw detector, and an inspection object made of a steel material as an inspection object, for example, a welded portion between a truffle and a deck while self-propelling while maintaining the bottom surface of a steel deck in a bridge or the like with magnetic force. It can perform flaw detection work such as crack inspection.

The road surface of an elevated road such as a pier is constructed by asphalt pavement on a steel deck. The steel slab is made of steel plates (deck) with a predetermined thickness, and for reinforcement on the lower surface of the deck, a plurality of steel plates are arranged at equal intervals in the road surface width direction, each of which is a U-shaped section steel that extends in the road surface vertical direction. It is constructed by welding a certain truffle. Steel slabs are repeatedly subjected to loads centered on the part where the tire part of the vehicle passes (two parts with a width of about 50 cm per lane), and fatigue cracks occur in the welded part of the deck and the trough rib over the years of service. Can occur. As a high-accuracy method for fatigue inspection of a welded portion, a method in which flaw detection is performed by ultrasonic echoes at a tire passage portion in a steel deck is conventionally known. And for ultrasonic flaw detection of welds located at high places such as welds between decks and trough ribs on elevated roads such as bridge piers, tire type ultrasonic waves are attracted and held on the lower surface of the steel slab by magnetic force. There has been proposed a mobile flaw detector that performs flaw detection on a welded portion by ultrasonic waves by rolling a probe along a weld line between a deck and a trough rib (Patent Document 1).
JP 2008-249510 A

  In the technique of Patent Document 1, the movement of the flaw detector along the weld line is a manual operation. For this reason, a scaffold is installed under the steel slab and work is performed on it, and work in a narrow area in a dark place is a heavy burden on the operator. In addition, the tire-type ultrasonic probe is equipped with an ultrasonic transmission / reception unit, transmits / receives ultrasonic waves through a tire that is in contact with the object to be inspected, and performs flaw detection by echo analysis. . In the structure of Patent Document 1, the ultrasonic transmission / reception unit is directly affected by the inclination of the vehicle body due to the state of the surface of the inspection object, and the direction of the ultrasonic wave changes. This may have an adverse effect on measurement accuracy. Further, in the structure of Patent Document 1, the rubber part of the tire is interposed in the ultrasonic transmission path, and since it is not a direct contact, the physical properties of the rubber affect the transmission of the ultrasonic signal, which affects the measurement accuracy. There was also concern.

  In view of the above, there has been a need for an inspection apparatus that is light, self-propelled, and has a small burden on the operator. In the present invention, the ultrasonic probe is brought into direct metal contact with the part to be inspected, and this contact state is maintained regardless of the state of the surface to be inspected. is there. Also, when the ultrasonic probe is in direct metal contact with the surface to be inspected and is self-propelled, convex parts such as weld beads interfere with the ultrasonic probe, and it is impossible to run or work is inefficient or avoided. There was a problem that a device was separately required and the structure was complicated.

  According to the present invention, a conventional self-propelled inspection apparatus of a remote control type that can be directly brought into contact with a flaw detection portion as an ultrasonic probe and can maintain this contact state regardless of the state of the surface to be inspected. It is intended to solve this problem.

  The self-propelled flaw detection apparatus of the present invention performs flaw detection of an object to be inspected made of steel by ultrasonic waves from the lower surface side, and holds the self-propelled vehicle body and the vehicle body by magnetic force on the lower surface of the object to be inspected. Means for making contact with the lower surface of the object to be inspected, a contact body attached to the vehicle body, position adjusting means for the contact body, and ultrasonic waves that are provided on the contact body and moved in contact with the lower surface of the object to be inspected. The ultrasonic probe for inspecting the inspection object by the inspection body and the contact body are provided on the lower surface of the inspection object to maintain the contact of the contact body and the ultrasonic probe with the lower surface of the inspection object when the vehicle body is self-propelled. And a self-propelled flaw detector comprising elastic means for urging it toward the surface.

  The elastic means is disposed so as to act independently at a portion separated in the moving direction of the vehicle body, and can be constituted by a pair of springs. The contact body can be constituted by a thread that slides and moves on the lower surface of the object to be inspected, and the pair of springs are provided at each end of the thread. Further, the sled can have a bent portion that is bent in the direction away from the object to be inspected at the front end in the moving direction.

  According to the present invention, when the vehicle body moves, the contact body and the ultrasonic probe attached thereto can maintain direct contact (metal contact) with the object under elasticity and depend on the moving direction. Therefore, since this direct contact state can be maintained, flaw detection using ultrasonic waves can be performed with high accuracy. In addition, while avoiding the work in a narrow place in a dark place where the burden on the worker is very heavy, such as constructing a scaffold and then performing an inspection by bringing the ultrasonic probe directly into contact with the surface to be inspected Even if a convex part such as a weld bead is on the surface to be inspected, it can be overcome, and self-propelled work can be performed with high efficiency.

FIG. 1 is a perspective view schematically showing the structure of a steel deck. FIG. 2 is a front view of the self-propelled robot for ultrasonic flaw detection according to the present invention, and shows a state in which flaw detection is being performed on the steel floor slab from its lower surface. FIG. 3 is an enlarged view of the welded portion of FIG. FIG. 4 is a side view of the self-propelled robot for ultrasonic flaw detection according to the present invention (viewed in the direction of arrow IV in FIG. 2) (illustration of the steel deck is omitted until FIG. 10 below). FIG. 5 is a plan view of the ultrasonic flaw detection self-propelled robot according to the present invention (viewed in the direction of arrow V in FIG. 2). FIG. 6 is a perspective view of the self-propelled robot for ultrasonic flaw detection according to the present invention viewed from above with the wheel facing down, and shows the structure of the ultrasonic flaw detection portion. FIG. 7 is a perspective view of the self-propelled robot for ultrasonic flaw detection according to the present invention as seen from above with the wheels facing down. FIG. 8 is a perspective view showing the attachment portion of the ultrasonic flaw detection probe during flaw detection from the lower surface of the steel slab shown in FIG. FIG. 9 is a perspective view showing the attachment portion of the ultrasonic flaw detection probe as seen from the top of FIG. FIG. 10 is a plan view of the attachment portion of the ultrasonic flaw detection probe (as viewed in the direction of the arrow X in FIG. 9). FIG. 11 is a side view of the attachment portion of the ultrasonic flaw detection probe (a view taken in the direction of the arrow XI in FIG. 2).

  The case where the present invention is used for inspection of a welded portion between a deck and a trough rib in a steel deck (inspected object of the present invention) in a bridge or the like will be described below. FIG. 1 schematically shows the structure of a steel slab. As is well known, the steel slab is made of a steel plate, and the lateral ribs 9 are spaced along the main girder ribs 8 along the center of the road. A plurality of trough ribs 12 each having a U-shaped cross section and extending in the longitudinal direction of the road surface are provided between the lateral ribs 9 on the lower surface of the deck 10 and spaced apart in the road surface width direction. Arranged. As shown in FIG. 2, the opening end (the upper end in FIG. 2) of the truffle 12 is welded to the lower surface of the deck 10, and its weld (bead) is indicated by W (the weld W in FIG. 2 is enlarged in FIG. 3). The welded portion W extends in the length direction of the truffle 12 (the direction perpendicular to the plane of FIG. 2). The deck 10 and the trough rib 12 have a finite length in the length direction, and the deck 10 and the trough rib 12 adjacent to each other in the length direction are welded by a welding portion (bead) (not shown) in the road width direction.

  Reference numeral 14 denotes a self-propelled robot as the self-propelled flaw detector, and welding is performed by self-propelling in the direction of the welded portion W (perpendicular to the plane of FIG. 2) while the lower surface of the deck 10 is attracted and held by magnetic force. The unit W is configured to perform flaw detection using ultrasonic waves. Although the vehicle body of the self-propelled robot 14 is composed of various parts, the whole is denoted by 16 for convenience of explanation. Driving wheels 18 with tires are provided on the left and right of one side of the vehicle body 16 in the traveling direction of the robot 14, and left and right driven wheels 19 are provided on the opposite side. The wheels 18 and 19 have axles parallel to the deck 10. The driving wheel 18, the side, and the driven wheel are connected by a belt 20. An electric motor unit for driving the drive wheels 18 is generally indicated by 21 for the sake of brevity. The motor unit 21 is provided with an electric motor and a gear for transmitting the output shaft of the electric motor to the drive wheels 18. The electric motor is configured to be reversible so that it can move in either the front or rear direction along the welded portion W. Further, the electric motor is connected to an external battery by a power cable (not shown), a drive control circuit for the electric motor is also provided outside, and the operation of the robot 14 can be controlled by a wired operation from the outside. The use of an external battery is a measure against early consumption due to an increase in the size of the battery.

  The vehicle body 16 is provided with an overhanging portion 16-1 (see FIGS. 6 and 7, etc.) on one side with respect to the traveling direction, and the overhanging portion 16-1 is provided with a guide wheel mounting portion 16-2. The wheel mounting portion 16-2 is parallel to the inclined surface 12-1 of the truffle 12 at the time of inspection of the steel slab (in the direction perpendicular to the paper surface of FIG. 2). As shown in FIG. 5, the guide wheel mounting portion 16-2 includes a pair of guide wheels 22 that are spaced apart in the robot front-rear direction. The guide wheel 22 has an axle parallel to the inclined surface 12-1 of the truffle 12 when the steel deck is inspected (see also FIG. 2). By rolling on the slope 12-1, the movement of the robot 14 along the welded portion W (in the direction perpendicular to the plane of FIG. 2) is assisted.

  Facing the deck 10 in FIG. 2, a permanent magnet 24 (adsorption holding means of the present invention) is provided on the vehicle body 16. Permanent magnet 24 is more clearly shown in FIG. The permanent magnet 24 is spaced apart from the deck 10 so as not to interfere with the running of the robot 14, but the direction of the magnetic field is directed in the vertical direction, and the robot 14 is efficiently attached to the deck 10 by a strong magnetic force. Can be sucked and held. Since the permanent magnet 24 is located at or near the center of gravity of the vehicle body 16 as shown in FIG. 7, even if the orientation of the main body deviates from the direction along the trough rib for some reason, it is rotated around the center of gravity axis, It is easy to go straight. In addition, auxiliary permanent magnets 26 are provided at both ends of the guide wheel mounting portion 16-2 of the vehicle body 16, and the permanent magnet 26 is in a direction in which the guide wheel 22 is brought into contact with the inclined surface 12-1 of the truffle 12 by its magnetic force. It sucks and plays the role of making the movement of the robot 14 along the welded part W, which is the part to be inspected, smoother by the guide wheel 22 being guided.

  In the present invention, an ultrasonic flaw detection unit 28 that performs ultrasonic flaw detection while maintaining contact with the surface to be inspected and is attached to the body of the robot is provided. The ultrasonic flaw detection unit 28 includes an ultrasonic flaw detection probe 30, a contact body (a thread 34 described later in the present embodiment), and an elastic means (a spring 40 described later in the present embodiment). The ultrasonic flaw detector 28 includes a sliding body 27. The sliding body 27 has a vehicle width as indicated by an arrow a with respect to the sliding groove 16-3 in the overhang 16-1 of the vehicle body 16 as shown in FIG. It is accommodated so as to be slidable in a direction (a direction parallel to the deck surface and perpendicular to the ribs), and the ultrasonic flaw detector 28 is also slidable in the same direction a. One end of a rack 29 is attached to the sliding main body 27, and the other end of the rack 29 is introduced into the adjustment block 16-4 in the overhanging portion 16-1 of the vehicle body and is orthogonal to the adjustment block 16-4. It is screwed into a pinion (not shown) that is arranged (the rack 29 constitutes the position adjusting means of the present invention). As shown by 31 in FIG. 6, the shaft end of the pinion is somewhat protruded from the upper part of the adjustment block 16-4, and the pinion shaft end 31 is provided with an engaging portion 31A with a hexagonal bar spanner. The rack 29 and the sliding main body 27 connected to the rack 29 are moved back and forth in the direction of arrow a by rotating the tool back and forth by operating the tool from the outside, so that the ultrasonic flaw detection unit 28 in the vehicle width direction, and further ultrasonic flaw detection. The optimum position of the probe 30 relative to the part to be inspected can be adjusted, and the later-described thread 34 as the contact body and the spring 40 as the elastic means move together, so that these proper functions are not impaired.

  The ultrasonic testing probe 30 performs ultrasonic testing by moving while maintaining contact with the lower surface of the deck 10. That is, an ultrasonic wave is emitted from the ultrasonic flaw detection probe 30 in an oblique direction as indicated by a one-dot chain line L in FIG. 2 (see also the enlarged view of FIG. 3), propagates through the inside of the deck 10 in contact therewith, and is welded. The reflected wave is reflected from the portion W, and the reflected wave returns to the inside of the deck 10 and is received via the ultrasonic flaw detection probe 30 in contact therewith, and the welded portion W can be flawed by analyzing the received wave (echo). . That is, in the enlarged view of FIG. 3, a crack in the welded portion W is represented by C, and the crack C progresses from the welding root portion p between the trough rib 12 and the deck 10 to the inside of the deck 10. Therefore, accurate flaw detection of the crack C becomes possible by ultrasonic waves emitted obliquely from the ultrasonic flaw detection probe 30 as indicated by L. On the other hand, in principle, it is necessary to maintain contact between the ultrasonic testing probe 30 and the deck 10 in the case of ultrasonic flaw detection. However, in reality, the deck 10 as an object to be inspected is inevitable with some inclinations. Since undulation exists and is directly affected by the inclination of the vehicle body, it is necessary to maintain surface contact between the ultrasonic flaw detection probe 30 and the deck 10 for highly accurate inspection. In addition, there is a welded portion (mostly a convex portion) between the decks adjacent in the longitudinal direction in the road surface width direction, and this can be an obstacle in the case of a self-propelled robot as in the present invention, A means is needed to ensure that this can be overcome. Therefore, in the present invention, while performing flaw detection with the ultrasonic flaw detection probe 30, surface contact between the ultrasonic flaw detection probe 30 and the deck 10 as the object to be inspected is ensured regardless of subtle undulation or inclination of the deck surface. Moreover, it is set as the structure which can get over a convex part like a weld bead. That is, FIG. 8 shows a portion of the ultrasonic flaw detection probe 30 in the flaw detection robot of the present invention. The ultrasonic flaw detection probe 30 has a rectangular block shape, and is formed in the rectangular opening 27-1 of the sliding body 27. The ultrasonic flaw detection probe 30 is relatively movable up and down and left and right with respect to the vehicle body 16 with some clearance (backlash). As is well known, the ultrasonic flaw detection probe 30 includes an ultrasonic transmission unit and a reception unit, and an inspection object can be detected by ultrasonic transmission / reception on the end face 30. A cable 32 for supplying control signals and power to the ultrasonic flaw detection probe 30 is also provided. An ultrasonic flaw detection probe mounting plate 33 is arranged at a distance from the sliding main body 27 in the vertical direction, and the ultrasonic flaw detection probe 30 is disposed on the side away from the sliding main body 27 at a rectangular opening 33 ′ of the ultrasonic flaw detection probe mounting plate 33. The ultrasonic flaw detection probe is fixed to a sled 34 that surrounds the ultrasonic flaw detection probe and extends in a hook shape in the front and rear directions in the moving direction at the end where the ultrasonic flaw detection probe mounting plate 33 is inserted. Yes. The thread 34 constitutes the contact body of the present invention.

  As shown in FIG. 9, the sled 34 has an upper surface (contact surface with the object to be inspected) flush with a contact surface 30 'with the surface to be inspected of the ultrasonic flaw detection probe 30 (see also FIG. 11). The sled 34 is fixed to the side surface of the ultrasonic flaw detection probe 30 by appropriate means such as caulking (an integrated structure of the sled 34 and the ultrasonic flaw detection probe 30 is also possible in some cases). The loose-fitting structure of the ultrasonic flaw detection probe 30 with respect to the sliding body 27 is such that the ultrasonic flaw detection probe 30 and the sled 34 fixed to the ultrasonic flaw detection probe 30 follow the slight inclination or undulation of the deck surface and The posture of the sled 34 is changed to maintain the surface contact with the deck surface. Further, the sled 34 has a U-shaped portion (saddle-shaped portion) 34- in front of and behind the robot in the longitudinal direction of the robot (the moving direction of the robot for inspection of the weld W (arrow f in FIG. 10)). 1 and the U-shaped portion 34-1 before and after the robot moving direction is somewhat bent in the direction away from the deck 10 surface like a ski. As shown in FIG. 10, the sled 34 is integrally formed with a link portion 34-2 that connects the front and rear U-shaped portions 34-1 to the left and right of the robot moving direction f. And as shown in FIG. 9, it is attached to the ultrasonic flaw detection probe attachment plate 33 by a pin 36. Further, as shown in FIG. 8, two spring guide bars 38 stand upright away from the sliding body 27 in the vehicle body moving direction, and one end of each spring guide bar 38 is attached to the sliding body 27 and the other end. Is loosely fitted to the ultrasonic inspection probe mounting plate 33.

  Further, a spring 40 (elastic means of the present invention) is fitted into the spring guide rod 38. One end of the spring 40 is hooked on the sliding body 27 and the other end is hooked on the ultrasonic flaw detection probe mounting plate 33. The ultrasonic flaw detection probe mounting plate 33 is urged away from the sliding body 27. In other words, the sled 34 and the ultrasonic flaw detection probe 30 attached to the ultrasonic flaw detection probe mounting plate 33 are moved away from the vehicle body by the spring 40. It is energized. When the flaw detection shown in FIG. 2 is performed, the spring 40 contracts somewhat against its elasticity, so that the ultrasonic flaw detection probe 30 contacts the lower surface of the deck 10 under a pressure corresponding to the contraction of the spring. As shown in FIG. 11, two springs 40 are provided apart from each other in the robot moving direction f for inspection (corresponding to the direction perpendicular to the paper surface of FIG. 2), so that the deck surface has a slight inclination or undulation. Even if there is a vibration, the two springs 40 on the front and back follow each other, and the postures of the ultrasonic flaw detection probe 30 and the sled 34 are automatically corrected. The posture is adjusted by appropriately tilting the ultrasonic flaw detection probe 30 back and forth in the moving direction, and the surface contact (metal contact) between the ultrasonic flaw detection probe 30 and the inspection surface is maintained regardless of the inclination or undulation of the non-inspection noodles. When the robot moves, the sled 34 smoothly slides with respect to the surface to be measured, thereby maintaining contact with the surface to be measured of the ultrasonic testing probe 30 supported by the sled 34, It is possible to realize a flaw inspection with high precision of a contact portion W. Then, a thread that supports the ultrasonic flaw detection probe 30 for a convex obstacle in the robot transfer direction such as a connecting portion of the adjacent deck 10 in the longitudinal direction (located in the orthogonal direction on the paper surface of FIG. 11). 34 is provided with U-shaped portions 34-1 that are bent like the tip of the ski in the direction away from the deck surface at both ends in the moving direction (arrow f), so that the convex portion is self-powered in any direction of movement. And can continue the work by the self-propelled robot without interruption.

10 ... Deck 12 ... Traff Rib 14 ... Self-propelled robot 16 ... Car body
16-3… Sliding groove
18, 19 ... wheels
24, 26 ... permanent magnet 27 ... sliding body 27
28 ... Ultrasonic flaw detector 29 ... Rack (the pinion constitutes the position adjusting means of the present invention)
30 ... Ultrasonic flaw detection probe 31 ... Pinion shaft end 33 ... Ultrasonic flaw detection probe mounting plate 34 ... Thread (contact body of the present invention)
34-1 ... U-shaped part of thread (bent part of the present invention)
38 ... Spring guide rod 40 ... Spring (elastic means of the present invention)
W ... Welded part (bead)

Claims (6)

  A self-propelled flaw detection device using ultrasonic waves from the lower surface side of an inspection object made of steel, a self-propelled vehicle body, means for adsorbing and holding the vehicle body on the lower surface of the inspection object by magnetic force, A contact body that is attached to the vehicle body so as to move in contact with the lower surface, position adjustment means for the contact body, and provided on the contact body, and inspects the inspection object by ultrasonic waves by moving in contact with the lower surface of the inspection object. An ultrasonic probe, and an elastic means provided on the contact body for biasing the contact body toward the lower surface of the object to be inspected so as to maintain the contact of the contact body with the lower surface of the object to be inspected and the ultrasonic probe when the vehicle body is self-propelled A self-propelled flaw detector.   2. The self-propelled flaw detection apparatus according to claim 1, wherein an ultrasonic probe and elastic means move together with the contact body during the movement for position adjustment.   3. The self-propelled flaw detection apparatus according to claim 2, wherein the elastic means independently urges the contact body toward the lower surface of the object to be inspected at a portion separated in the moving direction of the vehicle body. 4. The self-propelled flaw detection device according to claim 3, wherein the elastic means is composed of a plurality of springs arranged at positions separated in the moving direction of the vehicle body.
  5. The self-propelled flaw detector according to claim 4, wherein the contact body includes a thread that slides on the lower surface of the object to be inspected, and the spring is provided at each end of the thread.   6. The self-propelled flaw detection apparatus according to claim 5, wherein the sled has a bent portion bent in the separating direction from the object to be inspected at the front end in the moving direction.

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