| 摘要 |
PURPOSE:To lower energy cost by preheating the edge parts of the standby coil in the jet type preheating furnace before the un-coiler of skelp to provide a suitable temperature difference from the central part of the skelp in forge-welded steel pipe production process. CONSTITUTION:The coil C of the skelp C is preheated at its edge parts to about 500 deg.C by the high-temperature exhaust gas from the preheating furnace 5 and heating furnace 6 of later processes admitted through an induction pipe 12 beforehand into a jet type preheating furnace 9. Next, it is passed in a welding machine 2, looper 3, heat-insulating duct 4, preheating furnace 5, heating furnace 6 and induction furnace 7 and its edge parts are forge-welded by a pipe making machine 8, whereby it is made to a pipe. At this time, the temperatue difference of the central part of the skelp at the heating furnace inlet and induction furnace outlet is detected by thermometers 13, 14, is compared in a comparator 18 and the preset required heat quantity is distributed in the heating furnace 6 by a load distributing setter 15. Further, a thermometer 16 for edges is provided at the furnace outlet and the difference between the central temperature and edge temperature at the furnace outlet is compared in a comparator 19. The deviation from the set value is then subjected to temperature controlling by an induction heating controller 17. |
