Patent ID: 8826513

Claim:
A twisting method for twisting free end portions of bar conductors for a stator or rotor bar winding of an electrical machine, comprising: providing a twisting fixture comprising at least one pocket member extended about a twisting axis and provided with a circular array of pockets having its center on the twisting axis, the pocket member including a main structure provided with an arc of adjacent pockets of said array and a secondary structure which is movably mounted with respect to main structure and which is provided with a further pocket of said array, each of the pockets of said array comprising a respective insertion opening, which is adapted to be passed through by one of said free end portions for inserting such free end portion into said pocket; providing a stator core or rotor core provided with a plurality of slots populated by a respective plurality of said bar conductors which are arranged with said free end portions protruding from a side of the stator core or rotor core, said protruding end portions forming a circular array of end portions; inserting into the arc of pockets of the main structure an arc of adjacent end portions of said array of end portions; a first twisting step of twisting the arc of end portions, which is inserted into said arc of pockets, by a relative rotational-translational motion between said core and said pocket member; the method further comprising: a step of axially translating the secondary structure with respect to main structure, for inserting, into said further pocket of the secondary structure, a further end portion of said array of end portions; and a second twisting step comprising simultaneous twisting, by means of a further relative rotational-translational motion between said core and said pocket member, the arc of end portions, which is inserted into the arc of pockets of the main structure, and the further end portion, which is inserted into the further pocket of the secondary structure.