| 摘要 |
1498201 Making plastics coated welded tube ALLIED TUBE & CONDUIT CORP 4 Nov 1975 [14 Aug 1975] 45805/75 Heading B3A [Also in Division F2] A method of producing plastics coated tubing from steel strip comprises supplying the strip 8, roll-forming the strip into tubular shape 12, welding the tube 14, cleaning the tube 16, sizing the tube 24, heating the tubing 34, coating with polymer 36, baking 40, cooling 42, the tubing being physically unsupported by any support means situated in the region in which the coating and baking occur, gripping the tube at 44 over a distance of at least two feet and pulled in a manner so as to maintain it in precise spacial location throughout the heating, coating and baking. The object is to ensure a polymer coating of uniform thickness. The tube may also be galvanized 20, chromated or phosphated 26, or a primer applied 32. Endless belts 48 over pulleys 52 are driven by a motor 50 controlled by a controller 60 sensing by roller 62 the speed of the sized tube. Strip 8 initially enters an accumulator 10 which stores loops of strip and welds them together rendering stoppage of the tube production unnecessary as strips are supplied and welded to each other. |
