Patent GB-1151793-A (GB)
Title: Improvements in or relating to Supporting and Manipulating Equipment for Shot Blasting Apparatus.
Inventor: MILLER SAMUEL RICHARD FRANCIS
IPC: B63C5/02
Filed: 1966-11-25
Abstract: 1,151,793. Blasting. CAMMELL LAIRD (SHIP REPAIRERS) Ltd. 6 July, 1967 [16 July, 1966; 25 Nov., 1966], Nos. 32081/66 and 52880/66. Heading B3D. Equipment comprises (a) A mobile carriage; (b) An adjustable tower or jib mounted on said carriage; (c) Means mounting or for mounting shot or grit blasting and like abrasive or impact cleaning apparatus on the tower or jib so that said apparatus can adapt itself to a curved or irregular surface to be treated when moved thereover; and (d) Means for urging the shot blasting apparatus against such a surface, the tower or jib and/or the mounting means for the shot blasting apparatus providing for raising and lowering of said apparatus and also for lateral reciprocating motion thereof in addition to the motion provided by movement of the carriage. Equipment for treating a ship's hull while in dry dock comprises a telescopic tower 11, 12, the inner section 11 being fixed to a turntable 13 on a self-propelled carriage 10. The outer section 12 runs vertically over the section 11 on rollers (14 )and is moved by wire ropes 15a and hydraulic winches 16, the free ends of the ropes being connected to an equalizing beam 15b pivoted to the upper part of the section 11. A rectangular frame 17 runs vertically over the section 12 on rollers (18) and is moved by ropes 19a and hydraulic winches 20. An arm 21, e.g. 30 feet long, secured to the frame 17 has at its extremity a turntable 22 carrying blasting apparatus including two guns 23, 24. The arm 21 is counterbalanced by detachable counter-weights 25. The turntable may carry two heating ducts mounted below the guns and movable with them for preheating the cleaned surface prior to painting. The blasting apparatus is preferably as disclosed in Specification 1,102,688, being designed to seal against the hull and carry out blasting and also to recover the shot and debris. Compressed air and vacuum pumps and ancillary equipment may be mounted on the carriage 10 and connected to the blasting apparatus by flexible pipes. Each gun is mounted on an independent system of links 26 and gimbals 27, 28 so that it can be advanced and retracted relative to the hull, rotated and tilted up and down. The gimbal movement is at least 5 degrees up or down and 5 degrees right and left. The gimbal mountings are fitted with castors 29, which may be spring- loaded, so that when the whole assembly is loaded against the hull it can move freely over plate-joints and minor projections both horizontally and vertically. Each gun has an hydraulic thrust ram 30 so that the assembly can be pushed out to contact the hull, the distance between retracted and forward positions being 12 inches. When contact is effected, a constant pressure, e.g. 300 1b. per gun, is maintained. The rams are normally in mid-position so that differences of plus or minus 6 inches can be taken up. Tilting is effected by an hydraulic ram 31, e.g. 45 degrees above horizontal and 5 degrees below. The whole gun assembly is mounted on a frame 32 running in a slide 33 on rollers (33a), so that by actuating a ram (34) the frame and guns can be moved horizontally along the hull backwards and forwards a distance of, e.g. 8 feet, to give a sweep of 16 feet. The top of the slide 33 is bolted to the turntable 22. When not in use the turntable together with the blasting apparatus is rotated anti-clockwise so that it lies parallel to the arm 21. It can be rotated 80 degrees clockwise and 10 degrees anti-clockwise by a ram (35). An operator's cabin 36 is located between the tower gun assemblies and contains a control console. A painter's platform 37, e.g. 16 feet long, is mounted above the guns. It is retractable on runners 38 so that it does not interfere with the tilting of the guns or foul the hull when this overhangs the turntable. A screen is provided to prevent paint falling on the guns. The platform may be mounted below the guns. In use, the equipment is lowered into the dry dock by a crane. The carriage 10 is moved into position under its own power and trimmed for level by operating four hydraulic jacks with which it is provided; the jacks may be automatically self-levelling. The tower is extended so that the guns are level with the highest point of the area to be cleaned. The tower and turntable 22 are rotated to offer up the guns to the hull. After contact has been made by both guns at the requisite angle of tilt, the turntables 13, 22 are locked. The pressure in the thrust rams 30 is then applied. The guns and the traversing ram (34) are started; the ram (34) is capable of working at 5-32 feet/min. When the frame 32 reaches the end of its slide 33 it pauses sufficiently to allow the guns to drop, e.g. 12 inches, by lowering of the frame 17 and/or the tower section 12, after which the frame reverses its travel; this may be done electrically. Alternatively, the guns may be moved downwardly and laterally simultaneously. Controls are provided in the cabin for (a) raising/lowering the tower section 12 and frame 17 in steps or continuously, (b) rotating turntable 22, (c) rotating turntable 13, (d) operating tilt rams 31, (e) operating thrust rams 30, (f) operating traversing ram (34) and (g) operating valve means controlling the delivery of shot to the guns. Movements (a) (lowering only), (e) and (f) may be controlled automatically as well as manually. Movements (a), (b) and (c) may also be controlled from a console on the carriage 10, a positive interlock preventing operation of these controls when the operator is at the console in the cabin 36. It is preferably possible to retract either gun separately so that only one gun is used when cleaning awkward areas; the stroke of the gun along the slide 33 is then variable by manual control. Each thrust ram may be provided with a calibrated dial on the control console to indicate to the operator the position of each gun. When the gun is within one inch of its maximum travel towards or away from the hull a warning light or other alarm operates. When a gun reaches its forward limit, an electric contact may cut off hydraulic power and supply of shot to the guns. When a gun reaches its rearward limit, a similar contact may cut off hydraulic power. Operators on the platform 37 may be protected by a canopy, comprising L-shaped brackets attached to the ship's rail. A back stay extends from the brackets to a part of the ship's deck and a further stay extends from the outer extremity of the brackets to the dock wall. The stays include tensioning members. Crossmembers extending between the brackets and the canopy are secured to these members. The canopy has a flap or down-turned part at its forward end to direct rain away from the operators. The above-described equipment is for use in treating the hull where the angle formed by the ship's side with the vertical does not exceed 45 degrees. Equipment for blasting the bottom of a ship's hull and at least a substantial area of the hull adjacent to the counter of the stem and elsewhere where the angle formed by the ship's side with the vertical exceeds 45 degrees comprises a mobile self-propelled carriage 39, Fig. 11, on which is mounted a slewing ring 40, angular movement being effected by hydraulic rams (40a) or an hydraulic motor. Arms 41 pivotally mounted on the slewing ring are raised and lowered by hydraulic rams 43 and carry a base-plate 44. An hydraulic motor 45 mounted on the base-plate drives a heavy trunnion shaft 48 journalled in bearings 49 on the base-plate, whereby a bracket (50) attached to the shaft can be rotated, preferably through 60 degrees on either side of a vertical plane. A yoke 51 pivoted to the bracket can be tilted by an hydraulic ram 53. A gimbal 54 pivoted within the yoke can be tilted by hydraulic rams 57. The blasting gun 56 is mounted on the gimbal at 58 so that it can tilt, e.g. plus or minus 5 degrees. The thrust required on the gun seal to keep the gun in contact with the hull is conveniently about 300 1b. The movement of the setting ram 53 is such that the gun can be raised say 12 inches. During operation the setting ram normally operates in the half-way position so that it can move plus or minus 6 inches according to local undulations in the hull. In order that it can do this the pressure on the ram is kept constant, a dial being provided in the control console 59 to indicate the gun position. When the gun is within one inch of the limit of its plus or minus 6 inches travel a warning light flickers on the dial; when the gun reaches its upward limit (plus 6 inches) the supply of shot to the gun is cut off; when the gun is in the fully retracted position power to the travel and slewing motions is cut off. In operation, the carriage 39 is lined up to the hull and the arms 41 raised so that the gun 56 contacts the ship's bottom with the ram 53 in mid-position and the yoke 51 and gimbal 54 rotated so that the gun face coincides with the ship's plates. The gun is then slewed horizontally to one side through about 40 degrees. The gun 56 is then started and the slewing mechanism operated so the gun moves sideways over the ship's bottom to form an arc, say 8 feet long, at a speed of 5-32 feet/min. with automatic reversal. Simultaneously the carriage 39 is driven forwardly at 4-20 inches/min. For cleaning the turn of the bilge, Fig. 14, the arms 41 are extended by a member 41a to which the base-plate 44 is secured.