METHOD FOR MAKING ANNULAR ARTICLES Russian patent published in 2002 - IPC

FIELD: plastic material working, namely processes for making ring-shaped articles. SUBSTANCE: method comprises steps of heating initial cylindrical blanks and expanding them in cone deforming rolls with opposite arrangement of cone bases and with different conicity degrees. One deforming roll is drive roll, other deforming roll - pressure roll. Expansion is realized by two stages. At first stage due to initial non-uniform reduction along height of cross section, blank is turned by predetermined angle. At second stage diameters of blank are simultaneously uniformly increased along the whole height of cross section. Two centering rollers are used; said rollers are arranged symmetrically relative to vertical plane passing through rotation axes of deforming rolls. Rotation axes of centering rollers are inclined relative to above mentioned vertical plane and to vertical plane normal relative to first vertical plane while providing stable arrangement of crossing point of said rotation axes in vertical plane passing through rotation axes of deforming rolls. It provides possibility for free and stable rolling of article along surface of centering rollers during the whole expansion process. EFFECT: enhanced efficiency of method. 4 cl, 2 dwg