Shaped groove countermatrix for rotary groove pulley matrix and countermatrix bending head pipe bending machines

摘要

A shaped groove countermatrix for a rotary groove pulley matrix and a countermatrix head pipe bending machine has a semicircular cross- sectional tract and an end tract (2) tapered, both longitudinally and transversely, according to substantially elliptic profiles (20). The end tract (2) has its cross section substantially determined by the arcs (4, 4') of two ellipses (12) with their major axes (6, 6') parallel to and slightly offset with respect to a plane (8) of longitudinal symmetry of the groove (10). The tapering of the end tract (2) starts from a substantially parabolic profile (14) which has its axis on the plane (8) of longitudinal symmetry of the groove (10) and its vertex (16) at a short distance from the exit edge (18) of the groove (10). A well (22) allows for feeding a lubricating fluid onto the groove (10) which is in fluid communication therewith through a hole (24) via a wick (24'). A check valve ( 26) allows recharge of the well (22) with the lubricating fluid.