AUTOMATIC TUBE CIRCUMFERENCE SCANNING APPARATUS

Abstract: An improved automatic tube circumference scan­ ning apparatus for automatically performing inspections, repairs and other works for a group of tubes arrayed in a narrow space as directed in the horizontal directions is disclosed. The improvements reside in that the apparatus is composed of an upper support/traverse sec­ tion (7) mounted on an upper tube in the group of tubes so as to be able to travel along a tube axis and to stop and grip said upper tube, a lower support/traverse section (11) mounted on a lower tube so as to be able to travel, stop and grip said lower tube, a flexible rail (8) extended vertically between the upper and lower support/traverse sections and fixed thereto, and a probe scanning section (16) mounted on the flexible rail (8) so as to be able to move up and down, which grips any arbitrary tube between the aforementioned upper and lower tubes for making a probe scan around the same tube.

Description: Field of the Invention: The present invention relates to an automatic tube circumference scanning apparatus that is favorable for use in a system for inspecting, repairing and cleaning horizontal tube groups, especially superheaters and reheater tubes in a boiler. Description of the Prior Art: Regarding boilers for use in a power plant, in Japan it is obliged to perform routine inspections according to the Electrical Enterprise Law, and since it is necessary to stop operation of a boiler when a routine inspection for the boiler is carried out, it is a common practice to perform inspections and repairs other than the routine inspection items coincidently with the routine inspection. Among these other inspections and repairs, the inspection and repair of boiler superheater tubes are carried out by workers after setting up a scaffold. The state of inspection and repair of the interior of a boiler is shown in Fig. 9 which is a longitudinal cross-section view, and in Fig. 10 which is a perspective view of a part encircled by line X in Fig. 9. In these figures, materials for setting up a scaffold are carried into a furnace c through a hopper b of a boiler a and a scaffold d is set up in the furnace. In this case, since the carry-in port for materials is limited to a narrow space such as the hopper b , the materials to be carried in must be formed as small as the size of the carry-in port, and also since introduction of a machine into the furnace is impossible, the setting-up within the furnace must entirely rely upon human labor, so that setting-up of the scaffold d necessitates a long period of time. In addition, in the case where heat transfer tubes e are arrayed as directed in the horizontal directions, workers would make measurement while staying in the space between the tubes, hence a precision of the measurement is lowered du to the bad environmental condition for working, also there are many places where measurement is impossible due to the narrow space, and reliability of the measurement is poor. JP-A-61 130 799 discloses a cleaning equipment for heat transfer pipe, where a vertical arm supporting member is slidably mounted on a horizontal rail. The vertical arm supporting member carries an elevator with an arm pivotably mounted thereon. Attached to the arm is a gadget capable of carrying out the cleaning work at the pipes extending parallel to the vertical arm. The whole apparatus is collapsably constructed in order to be insertable into the inner of a boiler through a manhole. Basically, this known equipment has the structure of an X-Y positioning system, which allows to clean straight running vertically oriented heat pipes. However, this prior art apparatus is not capable to treat horizontally oriented heat pipes arrayed in a narrow space, since the restriction of the possible movements to the extension of the axes of the apparatus does not allow to reach such tubes. JP-A-60 205 117 discloses a furnace wall cleaning and repairing device, where at least two independent robots are fixed to the furnace wall under magnetic force. A control and power unit, hanging in the middle of the furnace provedes power via cables and the dust removed from the furnace wall by the robots is sucked through hoses to the exterior. This known structure is not transferable to an automatic tube circumference scanning apparatus, since the prior art robots are designated to move at the vertical and even wall surface of a boiler rather than to move along the pipes. Moreover, this apparatus is also not capable of working along tubes, since the magnets need planar surfaces in order to constantly exert sufficient holding force. SUMMARY OF THE INVENTION: The present invention has been worked out in view of the above-mentioned background of the art, and one object of the invention is to provide an automatic tube circumference scanning apparatus which can automatically perform inspections and works for a group of tubes arrayed in a narrow space as directed in the horizontal directions, which can realize reduction of the labor for the inspections and works, and also which can enhance a precision and can achieve improvements in reliability. According to the present invention, there is provided an automatic tube circumference scanning apparatus comprising the features as claimed in claim 1. According to the present invention, owing to the above-featured novel construction, the automatic circumference scanning apparatus can automatically perform inspections and works for a group of tubes arrayed within a narrow space as directed in the horizontal directions, hence reduction of the labor for the inspections and works can be realized, also a precision of the inspections and works can be enhanced, and improvements in reliability of the inspections and works can be achieved. The above-mentioned and other objects, features and advantages of the invention will become more apparent by reference to the following description of one preferred embodiment of the invention taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS: In the accompanying drawings: Figs. 1 and 2 illustrate an upper support/traverse section included in a tube wall thickness measuring system for horizontal type superheater tubes in a fired boiler according to one preferred embodiment of the present invention, Fig. 1 being a front view, and Fig. 2 being a longitudinal cross-section view taken along line II-II in Fig. 1; Figs. 3 to 5 illustrate a lower support/traverse section included in the same tube wall thickness measuring system, Fig. 3 being a front view, Fig. 4 being a plan view, and Fig. 5 being a longitudinal cross-section view taken along line V-V in Fig. 3; Figs. 6 to 8 illustrate a probe scanning section included in the same tube wall thickness measuring system, Fig. 6 being a front view, Fig. 7 being a plan view, and Fig. 8 being a plan view of the same but in a chucking state; and Figs. 9 and 10 illustrate the states of inspection and repair within a boiler in the prior art, Fig. 9 is a longitudinal cross-section view, and Fig. 10 being a perspective view showing one portion encircled by line X in Fig. 9. DESCRIPTION OF THE PREFERRED EMBODIMENT: Referring now to Figs. 1 and 2, an upper support/traverse section 7 is shown in the state where guide rollers 2a are placed on the uppermost superheater tube 1 in a horizontal type superheater and chucking fingers 3a are gripping the uppermost superheater tube 1. These chucking fingers 3a are opened and closed by making use of a pneumatic pressure. In addition, two air hands 4a for supporting these chucking fingers 3a are connected via arms 6, respectively, to an air cylinder 5a, and thereby traverse in the left and right directions as viewed in Fig. 1 is made possible. Also, a flexible rail 8 is fixedly secured to the upper support/traverse section 7 and is suspended therefrom. Figs. 3 to 5 show the state where a lower support/traverse section 11 is mounted to the lowermost superheater tube 10 in the horizontal type superheater via guide rollers 2b and chucking fingers 3b. In this section also, air hands 4b for opening and closing the chucking fingers 3b and an air cylinder 5b for moving the chucking fingers 3b are mounted. To this lower support/traverse section 11 is mounted the bottom end of the flexible rail 8, and a tension motor 12 for tensioning this rail 8 and a gear 13 operatively coupled to the motor 12 as well as an electromagnetic brake 14 for stopping the tension motor 12 under the condition where a predetermined tension has been applied to the rail 8, are provided in association with the lower support/traverse section 11. Fig. 6 shows the state where a probe scanning section 16 having a supersonic probe 15 for measuring a tube wall thickness mounted thereon is provided, in a vertically movable manner, on the flexible rail 8 that is provided vertically so as to extend between the upper support/traverse section 7 and the lower support/traverse section 11. This probe scanning section 16 is provided with a motor 17 for vertical movement, and also provided with a gear 19 that is coupled with the motor 17 via a bevel gear 18, this gear 19 is meshed with the rack 9 fixedly secured to the flexible rail 8, and thereby the probe scanning section 16 is moved up and down. Furthermore, this probe scanning section 16 is associated with two chucking sections on the left and on the right, respectively, which sections are adapted to grip a tube 21 to be inspected that is located between the uppermost tube 1 and the lowermost tube 10. Referring now to Fig. 7, the probe scanning section 16 is associated with a tube sensor 22 which can detect a center of a tube diameter of the tube 21 to be inspected while moving in the vertical directions. If this tube sensor 22 detects the center of the tube diameter of the tube 21 to be inspected, the motor 17 for vertical movement is momentarily stopped. Subsequently, turning motors 23 for turning the left and right chucking sections 20 by 90°, are actuated. Successively, air cylinders 24 for closing the chucking sections 20 are actuated to fixedly secure the probe scanning section 16 to the tube 21 to be inspected. As shown in Fig. 6, a supersonic thickness probe 15 is loaded on a horseshoe-shaped rail 25 mounted to one of the chucking sections 20. On the outside of the rail 25 is cut a rack, which is meshed with two gears 26. These gears 26 are rotationally driven by a probe revolving motor 27, hence the horseshoe-shaped rail 25 meshed with these gears 26 revolves around the tube 21 to be inspected with the supersonic thickness probe 15 kept loaded thereon, and thereby the wall thickness of the tube 21 can be measured. When the measurement has been finished, the air cylinders 24 are actuated, and thereby the chucking sections 20 are opened. Then the turning motors 23 are actuated and thereby the chucking sections 20 are returned from the state shown in Fig. 8 to the state shown in Fig. 7. Thereafter, the motor 17 for vertical movement is actuated to transfer the probe scanning section 16 to the next tube to be inspected. While the movement in the left and right direction was described by referring to the air cylinders 5a and 5b in the above explanation, the upper and lower support/traverse sections 7 and 11 could be moved by making use of motor-driven rollers. In addition, while explanation was made in connection to an example of tube wall thickness measurement in the above-described embodiment, besides it is possible that the probe scanning section is loaded with various working apparatuses such as a contour measuring apparatus, a penetrative defect hunting apparatus, a fiberscope or a cleaning apparatus, and is subjected to similar operations to perform desired measurements and works. In essence, according to the present invention, owing to the provision of an upper support/traverse section mounted on an upper tube among a group of tubes arrayed as directed in the horizontal directions so as to be able to travel along a tube axis and to stop and grip said upper tube, a lower support/traverse section mounted on a lower tube appropriately separated from the upper tube so as to be able to travel, stop and grip said lower tube, a flexible rail extended vertically between the upper and lower support/traverse sections and fixed thereto, and a probe scanning section mounted on the rail so as to be able to move up and down, which grips any arbitrary tube between the upper and lower tubes for making a probe scan around the same tube, there is provided an automatic tube circumference scanning apparatus, in which inspections and works for a group of tubes arrayed in a narrow space as directed in the horizontal directions can be performed automatically, hence reduction of labor necessitated for the inspections and works can be realized, also a precision of the inspections and works can be enhanced, and improvements in reliability of the inspections and works can be achieved, and therefore, the present invention is industrially very useful.

Claims: An automatic circumference scanning apparatus characterized by an upper support/traverse section (7), being adapted to be mounted at an uppermost tube (1) of a group of tubes arrayed as directed in the horizontal direction, and comprising a stop and grip mechanism (3a), being adapted to move lengthwise said uppermost tube (1); a lower support/traverse section (11), being adapted to be mounted at a lowermost tube (10) of the group of tubes, and comprising a stop and grip mechanism (3b), being adapted to move lengthwise said lowermost tube (10); a flexible rail (8) extending vertically between said upper support/traverse section (7) and said lower support/traverse section (11) and fixed thereto; a probe scanning section (16) being mounted at said flexible rail (8) so as to be movable up and down along said flexible rail (8) and comprising a sensor (22) for automatically detecting any arbitrary tube (21) between said uppermost and lowermost tubes (1, 10) facing said sensor (22); and a supersonic wave probe (15) being pivotably mounted at said probe scanning section (16) between a first position in which said supersonic wave probe (15) is located between two horizontally adjacent tubes and a second position in which said supersonic wave probe (15) embraces a tube (21) in order to be adpated to measure the thickness of said tube (21) by turning said tube (21). The automatic circumference scanning apparatus as claimed in claim 1, wherein said probe scanning section (16) is mounted on a horseshoe-shaped rail (25) which is mounted on a chucking portion (20) for a tube (21) and can rotate around said tube (21).

Inventors: IWAMOTO, KEIICHI C/O NAGASAKI TECHNICAL INSTITUTE, KOIZUMI, KIYOSHI, MAEYAMA, TAKUZO KANSAI ELEC. POWER CO. INC, NII, KENICHI KANSAI ELEC. POWER CO. INC., SHIMOJO, SHIGERU KANSAI ELEC. POWER CO. INC., TORICHIGAI, MASAAKI C/O NAGASAKI TECHNICAL INST.
Applicants: MITSUBISHI JUKOGYO KABUSHIKI KAISHA, THE KANSAI ELECTRIC POWER CO., INC.
Application year: 1988
Main classification: F22B37
IPC codes: F22B37, F28G15, G01B21