TECHNOLOGICAL TOOL OF MILL FOR HELICAL ROLLING Russian patent published in 1995 - IPC

FIELD: metal pressure forming. SUBSTANCE: technological tool includes at least three rolls of a mill for helical rolling. The rolls have in zones of their input cone and a deforming ridge a cross section in the form of a circle; their output cone have dents and recesses on its surface, these dents and recesses, directed along a helical line, are included by an angle, equal to a guiding angle. Height of the dents, depth of the recesses and width of the dents along the output cone are being continuously increased from a zero value, and width of the recesses is being respectively decreased, achieving to an output end predetermined values. In order to make blanks, having square cross sections, total height of dents and recesses achieves dimensions, determined by a formula ; a pitch t of the dents along a perimeter of a cross section of the roll (in an output end of the output cone in a zone of outlet of the blank out of contact with the roll) is determined according to a formula . Upon rotation of the rolls the blank is being bitten by input cones of the rolls, deformed beforehand to an end portion of the deforming ridges of the rolls up to a round cross section, then upon further motion to the zone of the output cone the dents and recesses begin to form flat faces of the blank and its ribs. It is possible because of a close embracement of the blank by the deforming ridges of the rolls in such a way, that the blank is being turned by them around a rolling axis. EFFECT: enhanced structure of the technological tool. 2 cl, 5 dwg, 2 tbl