METHOD AND TOOL FOR PULL BORING OF INTERNAL HOLE IN BILLET MADE OF ZIRCONIUM AND ZIRCONIUM-BASED ALLOYS FOR ROLLING Russian patent published in 1999 - IPC

FIELD: mechanical engineering. SUBSTANCE: internal hole of billet is treated by draw boring at which tool is secured at stem end fed axially, while billet is rotated. Chips are removed in direction opposite to feed. Boring is performed with axial feed of tool which does not exceed the smallest value of two limiting feeds one of which satisfies condition of stem strength and other, condition of stem stiffness determined from given relations. Provision is made for continuous chips of thickness and width not exceeding 0.2 mm. Multiblade cutting tool has body, shank and operating part with hard-alloy cutting members, front guiding part with central hole and ports for delivery of lubricating fluid to cutting zone. Guide chamfers, 2.0- 5.0 mm long and 0.6-2.0 mm wide, are made on blades of cutting tools to facilitate centering of tool during treatment. Method and tool ensure vibration strength of system, reduce roughness and enhance accuracy of treated hole. EFFECT: enhanced efficiency. 2 cl, 2 tbl, 4 dwg