A method and a device for effecting automatic centering of an annular workpiece on a rotating surface

A method and a device for effecting automatic centering of an annular workpiece (2) on a rotating surface (1) having a rotational center (O), incorporating the following steps: a) arbitrarily positioning the workpiece (2) on the slowly rotating surface (1), b) applying a support for the workpiece (2) by means of a first contact member (6) and a second contact member (7) spaced apart from the first contact member, and both contact members individually contacting the workpiece and being synchronously movable in a guided reciprocating manner towards and away from the rotational center (O) of the rotating surface (1), c) gradually retracting said first and second contact members (6, 7) away from the rotational center (O) of the rotating surface (1) until the workpiece (2) is unaffected by the contact members (6, 7) during one revolution of the rotating surface (1), whereby the workpiece (2) has been centered and the center (A) of the workpiece (2) coincides with the rotational center (O) of the rotating surface (1), and d) arranging, at least at one of said spaced apart contact members (6, 7), means (8) for counteracting a friction force acting on the workpiece (2) in this position, which friction force otherwise would result in a force component acting upon the workpiece (2) for moving it radially outwardly from the center (O) of the rotating surface (1).