Patent ID: 6871524

Claim:
A method for the manufacturing an annular article, which substantially comprises metal, ceramic material, and/or polymer, comprising: forming an annular cavity ( 46 ) defined by a wall of a through hole in a die ( 34 ), the upper end surface of a tubular, lower punch ( 27 ), which is introduced into a lower mouth of the die hole, and a mandrel ( 35 ), which is introduced from below into the die hole through the lower punch to at least essentially on a level with the upper surface of the die; filling the cavity with a formable working material, which shall form said article; introducing an upper punch into the upper mouth of the die hole, so that a closed mould cavity is formed; simultaneously striking the upper punch and the lower punch towards one another at such a high velocity that the working material between the punches plasticizes and flows out and fills all parts of the mould cavity, when the punches are maximally moved towards one another, so that an annular body is formed; removing the upper punch through a relative movement upwards out of the die; expulsing the mandrel out of the annular body by action of a mandrel expulsor ( 170 ), which is pressed against the mandrel from above; and pushing the annular body from below out of the die by means of the lower punch, so that said annular article is obtained.