| 摘要 |
PURPOSE:To produce efficiently and continuously a square steel pipe by subjecting successively a steel strip having a prescribed width to top side corner and bottom side corner bending by means of longitudinal die plates synchronized with the feed speed during bend pressing and subjecting the same to welding, bead removing, leveling and standard size cutting after square forming with rolls. CONSTITUTION:The steel strip 1 which is un-coiled 2 is leveled by a leveler 4 and is welded at the front and rear ends by a welder 5. The strip is then cut to the prescribed width by an edge preparing machine 9 and is fed into a top side corner bending press 11 by constant speed feed rolls 10. The top side of the steel strip is successively bent to about 80 deg. in the press 11 by the longitudinal upper die 20 and lower die 30 moving synchronously at the feed speed of the strip 1 by cylinders 34, 39 during pressing. The steel strip enters a bottom side corner bending press 13 after top side corner forming 12 and is bent about 80 deg. at the bottom side 2 bend part by the longitudinal upper die 48 and lower die 49 operating similarly. The strip is thereafter subjected to roll 90 deg. forming 14, butt welding 15, 16, bead removing 18, shaping 19, leveling 20 and standard size cutting 21, by which the steel strip is made into the prescribed square steel pipe P. The efficient and continuous production of the square steel pipe P to the good shape is thus made possible.
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