GB1180651A - Internal surface applicator for tubular members - Google Patents

Abstract

1,180,651. Spray guns; coating apparatus. A. O. SMITH CORP. 30 May, 1967, No. 24883/67. Headings B2F and B2L. [Also in Division F2] Apparatus for coating the interior of pipes comprises a cantilevered boom arm supported against axial movement, airless spray applicator means rotatably mounted at the end of the arm, a non-rotatable liquid coating material line extending substantially axially of the arm, a rotary high pressure coupling the line to the applicator means, and a constanttorque hydraulic motor mounted on the arm adjacent the applicator means and coupled to rotate the latter. A boom arm 2 carries at one end a rotary spray head 1, is pivotally supported at its other end on a pedestal 3, and is normally supported by a roller 156 adapted to be raised and lowered by a jack 159. A pipe 7, to be spray-painted internally, is supported by rollers 11 journalled in pedestals 10 and driven by chains 19, the pipe being initially moved, while the spray means is inoperative, from an extreme left hand position through a spray booth 5 to the extreme right hand position shown. During said movement the pipe, while telescoping over arm 2, actuates a switch 163 to effect operation of jack 159 for lowering roller 156. The interior of the pipe is engaged by vertical stabilising rollers 125 and horizontal stabilising rollers 127 mounted on arm 2. Head 1 comprises a plurality of radiallydirected spray guns 22 mounted on a body 20 detachably secured to the end of a shaft 21 journalled in a housing 58 projecting axially from a housing 60 at the end of arm 2. A conical baffle 73, rigid with housing 58, carries an upwardly-directed spray gun 74 for coating a longitudinal weld in pipe 7. Each spray gun 22 comprises a barrel 24 provided at respective ends with a spray nozzle 26 and a liquid-supplying nipple 34, and containing a spring-closed valve needle 27. A pivoted arm 29, engaging the latter is linked by a rod 30 to a diaphragm 31 in a chamber 32, supply of compressed air to which, via a nipple 33, serves to unseat needle 27 to operate the spray gun. The nipples 34 are connected by radial passages to an axial bore 41 in body 20 and shaft 21, said bore being connected via rotary coupling 99 to a liquid pressure line disposed axially in arm 2. Nipples 33 are connected by axial passages in body 20 and shaft 21 to a circumferential groove in shaft 21, said groove being closed by a fixed annular member communicating via a solenoid valve 66 with an air pressure line disposed axially in arm 2. Coupling 99 comprises a fixed hollow body 104 closed by an end plate 106 and journalling a hollow spindle 101 on roller bearings 107, 109. Spindle 101 is connected at one end to bore 41 and at the other end via a passage 105 in body 104 to the liquid supply line 98. A liquid seal, mounted between body 104 and a reduced end portion of spindle 101, comprises end rings 115, 116 and a plurality of intermediate rings 113 made from glass-reinforced plastics and of the crosssections shown, the intermediate packings 114 being chamfered to provide clearances at the inner faces of the rings 113. Leakage from the seal is drained via a passage 119 in body 104 and a pipe 120. Shaft 21 is rotated via gearing from a constant-torque hydraulic motor mounted in housing 60. The spray guns are surrounded by a hollow cylinder 6 mounted on rollers 168, 169 and rotated via gearing 166 from a motor 167. To commence a painting operation, the hydraulic motor is energised to rotate head 1, and valve 66 is energised to operate the spray guns 22 and 74, the paint being caught by cylinder 6 and being deflected therefrom by scraper blades 173 into receptacles 172. The rollers 11 are then driven to move pipe 7 leftwards. When the right hand end of pipe 7 clears switch 163, roller 156 rises to engage a block 154 rigid with arm 2. Should roller 156 fail to rise, an abutment associated with to rollers 125 would engage a fixed and vertically-adjustable platform 144. The paint, which is normally of the epoxy resin type, is supplied at a pressure of from 2200 to 2400 lbs. per square inch, and the spray nozzles are positioned at a distance of from 6¢ to 7¢ inches from the interior surface of pipe 7.