Machining unit with a rotating head

A machining unit with a rotating head with at least two pairs of pivoting tools for machining of a non-rotating piece centered along an axis of rotation, comprising:

• a framework upon which a rotor is mounted including the rotating head and a spindle integral with this head, the rotor being provided with an axial conduit for a guiding cylinder of a wire to be machined, and coupled with means for providing rotational drive;
• means for axial guidance of the piece, this means being mounted by bearings in the spindle or the rotating head;
• means for maintaining and axially moving the piece;
• at least four tool supports mounted on the rotating head in such a way as to pivot around respective axles extending parallel to the rotation axis, each support comprising a transversely arranged command lever, and
• means for controlling pivoting, in conjunction with said command lever and including a rotating command element, that is axially movable in the rotor, and coupled to means for axially moving a command sleeve, and pairs of support members respectively arranged on each command lever and on the corresponding rotating element, each pair of drive mechanisms including a directing surface and a drive surface supporting itself against the directing surface, in a variable position, in relation to the movement of the rotating command element, said directing surface being located on the tool support and the corresponding drive surface being located on the rotating command element, each directing surface corresponding to a pivoting tool support having the shape of an helical portion whose axis coincides with the pivoting axis of said support, and the helical directing surfaces having respective pitches of opposite direction, wherein the command sleeve (19) is mounted coaxially on said spindle (101), in order to slide axially and to occupy a primary position, a secondary position and a middle position, this sleeve having two ellipsoidal drive surfaces (20a and 20b) at one of its ends, designed to co-operate with the helical directing surfaces (14a, 14b, 14c and 14d) of the drive members and to execute the plunge of the tools, and a phase displacement device designed to cause said command sleeve (19) to rotate a predetermined angle around its axis.