PIERCING MILL PROCESS TOOL (VERSIONS) Russian patent published in 2019 - IPC B21B19/04 

FIELD: manufacturing technology.

SUBSTANCE: invention relates to rolling and can be used for piercing workpieces used for production of seamless pipes. Technological tool of piercing mill for production of sleeves comprises working rolls, internal tool in form of mandrel and retaining tool in form of drive disks. Working rolls according to the first version consist of articulated conical sections of piercing and rolling. Conical section of rolling consists of two conjugated zones with different taper angles, at that zone of conical section of roll rolling adjoining conical section of piercing is made with taper angle smaller than angle of taper of second zone of roll rolling section. Working rolls of the second version consist of articulated conical sections of piercing and rolling with cylindrical section located between them. Conical section of roll rolling is made of two interfaced zones with different taper angles. At that, roll conical section adjacent to cylindrical section has taper angle smaller than taper angle of second zone of roll section. Mandrel is located coaxially to the case and consists of articulated piercing section and a rolling taper section made of two articulated parts. At that, taper angle of conical part articulated with piercing section is smaller than taper angle of mandrel other conical part. Taper angles of taper sections of rolling are determined.

EFFECT: invention provides higher accuracy of geometric dimensions of a workpiece.

4 cl, 4 dwg