Patent GB-1483477-A (GB)
Title: Apparatus adapted movably to adhere to a wall of a large structure
IPC: B63B59/10
Filed: 1974-12-02
Abstract: 1483477 Blasting SANKO CO Ltd 2 Dec 1974 [11 Dec 1973 9 Feb 1974 30 March 1974 19 July 1974 15 Aug 1974 24 Sept 1974] 52101/74 Heading B3D [Also in Division B7] Apparatus adapted to movably adhere to a wall of a structure, such as an oil tank or ship, comprises four adhering members 1, 2, 3, 4, Fig. 1, means for attaching the members to a body of the apparatus so that the members are arranged in parallelism in two pairs 1, 2 and 3, 4 and one member of each pair moves in the opposite direction to the other member of the pair, means for synchronously driving all members, and means for switching off alternative members of each pair so that the members of each pair adhere to the wall alternately. The apparatus carries means for blast cleaning the wall of the structure and the adhering members, which may be electro or permanent magnets or vacuum holders are controlled so that the apparatus moves over the wall. In the embodiment shown in Fig. 1, the adhering members 1, 2, 3, 4 are in the form of electromagnets arranged in pairs with one member of each pair fixed to the opposite runs of respective ones of a pair of chains 7, 10 entrained about sprockets 6, 6<SP>1</SP>, 9, 9<SP>1</SP>. The sprockets 6, 9 are connected to further sprockets 11, 11<SP>1</SP> around which is entrained a chain 12 connected to the piston 15 of a cylinder 14. Reciprocation of the piston is controlled by a valve 17 operated by limit switches LS1, LS2 actuated by a member 16 on chain 10, the switches also acting to alternately energize the electromagnets of each pair. When it is desired to move the body to the right, members 2 and 4 are energized to adhere to the wall and the piston is extended so that the members of each pair move apart until switch LS1 is actuated whereupon the members 1 and 3 adhere to the wall, members 2 and 4 are deenergized and the piston retracted so that the members of each pair move towards each other. When diagonally opposite members are energized, the body 5 becomes inclined to cause an upward or downward movement of the body. In a second embodiment, the adhering members 1, 2, 3, 4, Fig. 5, are connected by pins 8 to the chains 7, 10 and are slidable along guides 33 which are mounted on pivots 31 on the body 5 and have their ends interconnected by rods 32. The body is supported by a cable 30 and the chains and members 1, 2, 3, 4 are connected in a similar manner to the previous embodiment to effect vertical movement of the apparatus. The guides 33 can be tilted about the pivots 31 by operation of a piston-and-cylinder device 34, 35 to change the direction of movement of the members 1, 2, 3, 4. The vertical movement may be effected by the cable 30. In a third embodiment, the adhering members 1, 2, 3, 4, Figs. 8 and 9, comprise electro or permanent magnets and are mounted on bases 41, 42, 43, 44 slidable along guide rods 40 under the control of chains 7, 10, 12 and a pistoncylinder device 14, 15 connected between the bases 43, 44. Each member has pairs of hydraulic cylinders 47, 48, 49, 50 having rods carrying rollers 55, 56, 57, 58, operation of the cylinders spacing the adhering members from the wall W so as to render the members inoperative. The adhering members are connected to the bases by springs 46 and spherical bearings 45 so as to be universally movable. The body 5 carries a grit blasting device having a sealing member 61 for engaging the wall, a blasting wheel 59 driven by a motor 65, and a bucket 62 for collecting grit and movable by a chain 63 to deliver the grit to a shoot 64. In a fourth embodiment, the adhering members are advanced by pneumatic cylinders into engagement with the wall of the structure and in a retracted position are spread from the wall by universally movable rollers. The chains are driven from a motor having a reversible clutch. In a fifth embodiment, Figs. 17, 18 and 19 the adhering members 1, 2, 3, 4 are carried by rods 95 mounted in plates 92, 93 and are urged by springs 46 against the wall W. The plates are supported for movement in channel shaped guide 90 by rollers 91 having recesses 94 providing clearance for the chains 7, 10. The chain 12 interconnecting chains 7, 10 is driven by piston-and-cylinder devices 14, 15 to effect movement of the adhering members. The body 5 has a blasting chamber 96 having an opening surrounded by a seal 61 and contains blasting nozzles 97 supplied with grit and compressed air through a pipe 110. A pressure tank 101 contains upper and lower hoppers 99, 100 having respective valves 103, 104, and an electrode plug 106 acting as a level indicator. A valve 107 controlled by a cylinder 108 regulates the flow of grit. If a small quantity of grit is in the lower tank, compressed air in the upper part of the tank is released so that the valve 103 opens and grit in the upper hopper is allowed to fall. When compressed air is again supplied to the upper tank, valve 104 opens and the grit falls to the lower tank which is under pressure and supplies the grit to the nozzles. Suction ports 111, 111<SP>1</SP> open into the blasting chamber 96 and are connected to cyclones 113, 113<SP>1</SP>. A duct 114 connected to the suction port of the cyclone is joined by a flexible hose to a dust bag 115.