| 摘要 |
The invention deals with a method of producing a steel-sheet trough as a lid shell for a reinforced-concrete manhole cover, a steel-sheet blank with punched holes for inserting anchor bolts and with or without vent pipes being bent to form the steel-sheet trough of base and encircling collar and being welded in its corner areas. Before the welding of the outer corners formed from the bent-up collar sections, pick-up stiffeners are welded into the inner corners. After the corner welding, the steel-sheet trough is turned and support profiles are welded onto the upturned base underside. The anchor bolts inserted into the punched holes are then welded into the base in diagonally opposite positions in pairs from the outside to the inside or vice versa in an intersecting diagonal welding sequence under shielding gas. Any vent pipes are also welded into their punched holes in a diagonal welding sequence. These welding sequences ensure a flat support form which makes subsequent aligning work unnecessary. <IMAGE>
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