METHOD FOR MAKING HOLLOW ARTICLE OF MASSIVE ROUND STEEL BLANK AND APPARATUS FOR PERFORMING THE SAME Russian patent published in 2001 - IPC

FIELD: process and equipment for making hollow article of massive round steel blank heated up to temperature of deformation by piercing in helical rolling mill with use of guiding members forming grooved pass. SUBSTANCE: method comprises steps of decreasing before piercing operation spacing between guiding members forming grooved pass relative to such spacing in stable mode of rolling; after rolling setting said spacing by value equal to standard value at stable mode of rolling. Due to compensation of efforts acting upon guiding members at deforming round steel blank and efforts providing small value of gap of grooved pass, above mentioned spacing is changed automatically. Apparatus for performing the method includes double -roll helical rolling mill and piercing mandrel placed between skew rolls with use of guiding members forming grooved pass such as discs. Free spacing between guiding members mounted between struts with possibility of rotation or motion may be adjusted in plane of guiding members according to diameter of round steel blank. Guiding member mounted with possibility of rotation or motion supports unit whose effort acts upon guiding member for reducing said spacing. EFFECT: possibility for centering system before piercing, particularly thick-wall hollow products by means of simple equipment. 5 cl, 2 dwg