METHOD FOR MAKING TANGENTIAL EXPANDERS AND APPARATUSES FOR PERFORMING THE SAME Russian patent published in 2002 - IPC

FIELD: plastic metal working in combination with heat treatment, particularly, manufacture of buildup oil piston rings for internal combustion engines, compressors and other piston mechanisms. SUBSTANCE: method comprises steps of forming coiled spring of flattened metallic band; gradually decreasing pitch of spring turns at constant fixation of bending zones; finally decreasing pitch of spring turns and simultaneously forming supporting beads on spring; forming V-shaped portion of made spring; winding spring onto mandrel to helix and simultaneously quenching it; separating from helix predetermined-length portion; placing it onto another mandrel, tempering it and cutting by separate expanders; simultaneously forming on each expander locking device. Apparatus for decreasing pitch of spring turns includes housing in which are arranged: spindle with profiling roller having radially placed pins, spindle with shaping roller, guiding roller, stationary mounted cam-eccentric and mechanisms for limiting pin motion. Said mechanisms are in the form of contour-follower guides with surfaces equidistant relative to surface of cam-eccentric. Pins engage with cam-eccentric and with mechanisms for moving them. Apparatus for winding V-shaped portion of tangential expander to helix includes housing with supporting mandrel on which are arranged: quickly detachable sleeve, lever with elastic roller and stripper. The last has helical end surface whose pitch is no less than height of wound helix. EFFECT: enhanced quality of tangential expander at lowered consumption of flattened steel band. 5 cl, 14 dwg