METHOD FOR MAKING HOLLOW DOUBLE-WALL SLEEVES AND APPARATUSES FOR PERFORMING THE SAME Russian patent published in 2004 - IPC

FIELD: plastic working of metals, possibly manufacture of sleeve type articles such as hollow sleeves with double walls.

SUBSTANCE: method comprises steps of turning tubular blank inside out by expanding it and shaping inner start portion; turning inside out deformed portion of tubular blank until forming hollow double wall sleeve; deforming said sleeve by shaping outer inlet portion due to reducing bottom part and necking wall of outer branch pipe. First apparatus for making hollow double-wall sleeves includes die arranged in lower plate and having guiding, working and outlet portions, punch mounted along the same axis as die on driven plate. Die has shaping part arranged between guiding and working portions and being in the form of truncated cone whose large base is joined with working portion. Second apparatus for making hollow double-wall sleeve includes die arranged in upper plate, lower plate rigidly joined with upper plate, hollow punch mounted on the same axis as die. Punch has stem portion and working portion having working zone in the form of hollow cylinder and end toroidal part. Punch has forming portion in the form of hollow truncated cone arranged between working and end portions; large base of said cone is joined with working portion. Cavity of forming portion is cone one, its diameter lowers towards working portion.

EFFECT: enhanced quality of multi-layer articles due to lowered deforming effort at initial time moment of sizing built-up articles.

3 cl, 5 dwg, 1 ex