METHOD FOR COLD ROLLING OF TUBES BETWEEN TWO MUTUALLY NORMAL PAIRS OF VARIABLE-RADIUS ROLLS Russian patent published in 1999 - IPC

FIELD: rolled tube production. SUBSTANCE: method is realized between two mutually normal pairs of rolls at cyclic alternative reduction of sleeve by pairs of rolls rotating towards outlet of ready tube, at moving rotation axes of rolls in mutually opposite directions and at forming gap between rolling surfaces of rolls. At reduction process mandrel is moved by means of rolls through sleeve along rolling axis. Beginning from position of first pair of rolls corresponding to equal speeds of metal at outlet of these rolls and their rotation axes and terminating in position of second pair of rolls corresponding to equal values of above mentioned speeds, mandrel is moved in direction opposite to rolling direction. Then mandrel is returned to its preceding position. Motion value of mandrel is equal to difference of integrated values of said speeds for respective integral of their rotation axes. EFFECT: lowered labor consumption of tube rolling due to feeding sleeve and tube by means of rolls, elimination of unfinished portion of sleeve. 9 dwg