Patent ID: 8881371

Claim:
Method for twisting preformed bar conductors for bar windings of electric machines, said conductors comprising a first and a second leg joined together by a connection portion, the method comprising the steps of: a) providing a twisting apparatus comprising a twisting device having at least a first and a second body coaxial with each other and extended around a twisting axis (Zt-Zt), and respectively comprising a first and a second circular array of pockets with center on such axis (Zt-Zt), said bodies being relatively rotatable with respect to each other around the twisting axis (Zt-Zt) in order to assume a first insertion configuration in which respective pockets of the first and second array are radially aligned with each other in pairs with respect to the twisting axis; b) loading, in a subset of said pockets, a plurality of said preformed conductors in a manner such that aligned pockets of the first and second array respectively receive a first and a second leg of a respective conductor, the loading step being such to leave a first residual subset of pockets free; c) driving the first and the second body in relative rotation around said axis (Zt-Zt), in order to distance the legs of the first plurality of conductors from each other by a first pre-established twisting pitch, until a second insertion configuration is reached in which a second plurality of pockets of said residual subset of pockets of the first and second body are radially aligned with each other; wherein the method also comprises, after the step c), the steps of: d) loading, in a second subset of said plurality of pockets, a second plurality of preformed conductors in a manner such that aligned pockets of the first and second array belonging to said second subset respectively receive a first and a second leg of a respective conductor; e) driving the first and the second body in relative rotation around said axis, in order to distance the legs of the conductors of the second plurality of conductors from each other by a second pre-established twisting pitch and to further distance the legs of the first plurality of conductors from each other by said second pre-established twisting pitch, therefore obtaining said first plurality of conductors having legs spaced from each other by a distance equal to the sum of said first and second pitch and said second plurality of conductors having legs spaced from each other by said second pitch.