PRODUCTION AND OPERATION OF PILGER MILL COMPOSITE MANDRELS FOR PRODUCTION OF LARGE- AND MEDIUM-DIAMETER HOT-ROLLED PIPES Russian patent published in 2014 - IPC B21B21/00 

FIELD: process engineering.

SUBSTANCE: invention relates to pipe rolling and can be used at production of composite mandrels of Pilger mills. One-piece cores are made from continuously-cast billets or profiled special iron from carbon grades of steel. Said core is bored from one end to cut tight-hand thread while bulge shaped to truncated cone with larger base on core end is made at opposite end. Locking parts are made mechanically from mandrel rejects and forged pieces of steel "25Х2М1Ф" or steel resisting the impact effects to cut the thread at the end opposite the lock. Core and lock are screwed together to produce a prefabricated structure. Billets produced by forging or ESR casting are heated to ductility temperature and pierced at helical rolling mill to sleeved with ID larger than large bases of the core truncated cones by 15-20 mm. Said sleeve is fitted on said prefabricated structure till contact with lock cone to roll-and-knurl the sleeve on cores at Pilger mills. Thermal treatment of composite mandrel billets is carried out to produce 40-50 mm deep sorbite jacket on the surface. Then, said billets are machined to composite mandrels.

EFFECT: decreased consumption of heat-and-wear-resistant steel.

5 cl, 1 tbl