COOLED PIERCING MANDREL Russian patent published in 2020 - IPC B21B25/00 

FIELD: pipe rolling production.

SUBSTANCE: invention relates to tubular production and can be used at helical rolling mills at piercing billets from carbon, alloyed steel grades and steel of type 13Cr using cooled mandrels. Mandrel comprises working, calibrating and cylindrical sections. Possibility of increased resistance of cooled mandrels, reduced costs and downtime of equipment is provided due to that mandrel is made with cavity of variable cross-section and shaped outer surface from mandrel end by 0.25÷1.0 of length of working section in form of alternating elevations and recesses. Cavity of mandrel is formed by conjugated coaxial cylindrical and conical surfaces made at points of conjugation along radial rounding, difference of length of mandrel and cavity is 0.5÷1.5 of outer diameter of mandrel. Elevations and recesses on outer surface of mandrel can be made with pitch of not less than 0.01 of length of mandrel, width of not less than 0.005 of mandrel length and depth of not more than 0.005 of outer diameter of mandrel.

EFFECT: cooled mandrel of piercing mill is proposed.

1 cl, 2 dwg