Method And Fixture For Twisting End Portions of Bar Conductors, In Particular For Bar Windings of Electric Machines

Abstract

A twisting method (100) is described, for twisting free end portions (2A, 3A, 2A′, 3A′) of bar conductors (1, 1′) for the stator or rotor bar winding of an electrical machine, comprising: a step of providing (101) a twisting fixture (10) comprising at least a pocket member (11) extending about a twisting axis (Z-Z) and provided with a circular array (S1) of pockets having its center on the twisting axis (Z-Z), the pocket member (11) including a main structure (11A) provided with an arc (R1) of adjacent pockets of said array (S1) and a secondary structure (11B) which is movably mounted with respect to main structure (11A) and which is provided with a further pocket (11B′) of said array (S1), each of the pockets of said array (S1) comprising a respective insertion opening (11A″, 11B″), which is adapted to be passed through by one of said free end portions (2A, 2A′) for inserting such free end portion into said pocket; a step of providing (102) a stator core (20) or rotor core (20) provided with a plurality of slots (24) which are populated by a respective plurality of said bar conductors (1, 1′) which are arranged with said free end portions (2A, 2A′) protruding from a side of stator core (20) or rotor core (20), said protruding end portions forming a circular array (T1) of end portions (2A, 2A′); a step of inserting (103) into the arc (R1) of pockets of the main structure (11A) an arc of adjacent end portions (2A, 2A′) of said array of end portions (T1); a first step of twisting (104) the arc of end portions, which is inserted into said arc (R1) of pockets, by relative rotational-translational motion between said core (20) and said pocket member (11); the method being characterized in that it further comprises: a step of axially translating (105) the secondary structure (11B) with respect to the main structure (11A), for inserting, into said further pocket (11B′) of the secondary structure (11B), a further end portion (2A) of said array (T1) of end portions; and a second step of simultaneous twisting (106), by means of a further relative rotational-translational motion between said core (20) and said pocket member (11), the arc of end portions, which is inserted into the arc of pockets (R1) of the main structure (11A), and further end portion (2A, 2A′), which is inserted into the further pocket (11B′) of the secondary structure (11B).

Dependencies are inferred from the claim text.