METHOD FOR SHAPING SHEET BLANK AT MAKING WELDED THIN-WALL SMALL-LOT PRODUCTION TUBES AND APPARATUS FOR PERFORMING THE SAME Russian patent published in 2000 - IPC

FIELD: tube production, namely shaping thin-wall welded small-lot production tubes of sheet material at making pilot mufflers and exhaust tract of engine. SUBSTANCE: method comprises steps of shaping sheet blank on mandrel at placing blank between movable member and mandrel; clamping edge of blank by means of clamping member; forming sheet blank by rolling it with movable member along cylindrical surface of mandrel until forming tubular blank from sheet blank; feeding tubular blank for welding. Apparatus for performing the method includes as movable member two clamping rollers with rotary levers supporting bearing units provided with screw gages and latches and also with two toothed sectors for fixing latches of rotary levers. Sheet blank is shaped on mandrel mounted with possibility of rotation by means of lever of drive unit and with possibility of arresting due to its fixation by stopper at rolling process. Axle of lever of driving unit is mounted eccentrically relative to rotation axis of shaping mandrel with possibility of rotation along respective circular groove. Clamping member with clamping surface is mounted on lever of drive unit with possibility of rotation and fixation. At shaping process sheet blank is placed between one clamping roller of movable member and shaping mandrel. When edge of sheet blank is clamped by means of clamping surface of clamping member, said roller is adjusted according to clamping effort to mandrel with the aid of screw gage and it is rolled around blank by 45 deg. Then rotary lever of roller is fixed on toothed sector by means of latch, stopper of mandrel is released, mandrel is rotated by means of lever of drive unit together with clamping member by angle 135 deg. Mandrel is fixed by stopper, axle of driving lever of mandrel is released and axle of driving lever together with clamping member are moved along circular groove by 135 deg. Clamping member is returned to initial position. Then second clamping roller of clamping member is adjusted according to clamping effort to mandrel by means of screw gage and it is moved to clamping surface of clamping member for rolling sheet blank by roller. At remaining spacing 1-2 mm until edge of sheet blank lever of second clamping roller is fixed with the aid of latch on toothed sector and process of shaping tubular blank from sheet one is repeated beginning from step of using first clamping roller of movable member. EFFECT: elimination of high costs at making pilot mufflers and exhaust tracts of engines. 2 cl, 1 dwg