Patent ID: 6968720

Claim:
A cold rolling apparatus for forming an annular piece ( 10 ) with an outer surface ( 11 ) having a given contour and an inner surface ( 12 ) having a given contour, starting from an annular blank, the apparatus comprising: a forming mandrel ( 21 ) rotatable about a first axis (X 1 ), the mandrel having a working surface ( 21 a ) with a contour corresponding to that of the inner surface ( 12 ) to be formed, a forming die ( 51 ) rotatable about a second axis (X 2 ) parallel to the first axis (X 1 ), the die having a cavity ( 52 ) with an inner working surface ( 53 a ) in form of a surface of revolution corresponding to the outer surface ( 11 ) to be formed, first motor means ( 70 , 72 ) for provoking rotation of the mandrel ( 21 ) and the die ( 51 ) about the respective axes (X 1 , X 2 ), second motor means for varying in controlled manner the distance between the first (X 1 ) and the second (X 2 ) axes, so as to radially compress the workpiece ( 10 ) between the working surfaces ( 21 a , 53 a ) of the mandrel ( 21 ) and the die ( 51 ); characterised in that the apparatus further comprises third motor means ( 43 ) for varying the relative axial distance between the mandrel ( 21 ) and the die ( 51 ), and wherein the mandrel ( 21 ) and an intermediate roller ( 31 ) are mounted on a plate ( 41 ) slidable along axial guide means ( 42 ) between a first, axially retracted loading position and a second, working position axially advanced towards the die ( 51 ), wherein in said second position the intermediate roller ( 31 ) is transversally interposed between and in contact with the mandrel ( 21 ) on one side, and a reaction assembly ( 90 ) provided with at least one idle roller ( 91 , 92 ) on the other side.