APARATUS FOR CENTERING MANDREL ROD AND FOR CHANGING MANDREL OF VACUUM MILL FOR SCREW ROLLING OF TUBES Russian patent published in 2005 - IPC

FIELD: plastic metal working at making tubes, possibly piercing and expanding tubes of refractory metals, namely apparatuses for centering mandrel rod and changing mandrel of vacuum mill for screw rolling of tubes.

SUBSTANCE: apparatus for centering mandrel rod and changing mandrel includes stationary centering device having movable centering sleeve in the form of cylinder with tip at one side and member for joining with drive unit arranged outside vacuum chamber at other side; additional vacuum chamber designed for inspecting and changing mandrel and communicated with main chamber of mill by means of flange and vacuum seal. Additional vacuum chamber has vacuum seal unit in other flange for extending rod outside chamber and supporting-regulating mechanism of mandrel rod with drive unit. Mandrel rod includes working, basic and supporting-drive portions and in addition it includes intermediate portion whose diameter is less that of working portion. Movable centering sleeve is elongated, its back end extends outside additional vacuum chamber through vacuum seal unit. Vacuum seal unit of basic portion of mandrel rod is arranged in back end of said sleeve having inner cavity in the form of cylindrical parts with diameters stepwise reduced from front end to back end and exceeding diameters of respective portions of mandrel rod. Hollow inserts are mounted between sleeve and mandrel rod with possibility of their motion along respective inner portions of sleeve and mandrel rod. Said inserts are provided with members of anti-friction materials.

EFFECT: enlarged assortment of elongated tubes made in vacuum condition, enhanced operational reliability of apparatus, improved efficiency of mill.

2 dwg