Patent ID: 8161788

Claim:
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 steps 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 ( 3 b , 4 b ; 4 b ′) 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.