Method for producing workpieces

A method for producing workpieces wherein a generally cylindrical preform (8) is formed by at least one pressure roller (7) into a finished workpiece (8.2), said method comprising the acts of:

• a. slidingly placing at least a portion of the preform (8) onto at least a first mandrel (3, 4′) which is slidably mounted in parallel with a longitudinal axis (A) of said preform (8),
• b. aligning said mandrel (3, 4′) such that a surface (3b, 4b;
• 4b′) thereof disposed within said preform (8) substantially defines a negative profile of an inner surface to be formed in the preform (8),
• c. causing a relative movement between said preform (8) and said at least one pressure roller (7) in a direction parallel to said longitudinal axis (A) while pressing said pressure roller (7) against the preform (8) in a direction generally perpendicular to said longitudinal axis (A), characterized in that step c. is performed such that material of the preform (8) is displaced by the pressure roller (7) in such a way that said mandrel (3, 4′) is moved longitudinally along said longitudinal axis (A) by the displaced material.