Clamp for retaining a piece to be worked and method for working a piece

Method (300) for working a piece (100), which provides for:

• a first step (301) of arranging a piece (100) to be worked, which is provided with at least two sides (102) that are opposite each other;
• a first working step (302), in which material is removed from said piece (100) at least at said sides (102) by means of a milling tool (400) in order to attain at least one first milled groove (101) on each said side (102);
• a second step (303) of arranging at least one clamp (1), which is provided with:
• a support body (2), which is fixed to a support base (200) in said second arranging step (304);
• at least two jaws (3), of which at least one is movably connected to said support body (2) and is actuatable to be moved close to or away from the other of said jaws (3);
• at least one insert (5) mounted on each said jaw (3);
• said inserts (5) each being provided with a retention portion (6), which is substantially counter-shaped with respect to a corresponding said first milled groove (101) and is susceptible of being inserted in said corresponding first milled groove (101);
• the retention portion (6) of each said insert (5) having, on a first reference plane (P1), a section with a first external profile (7) extended along at least one arc of circumference;
• the retention portion (6) of each said insert (5) having, on a second reference plane (P2) transverse to the first reference plane (P1), a section with at least one tapered second external profile (8) that is extended, narrowing up to one end (36) thereof which has at least one point in common with said first external profile (7);
• a first tightening step (304), in which at least one said jaw (3) is actuated to be moved such that the retention portions (6) of said inserts (5) are inserted in the first milled grooves (101) made on the opposite sides (102) of said piece (100) and block said piece (100) in a first work position;
• a second working step (305), in which said piece (100) is subjected to one or more working operations while said piece (100) is locked in said first work position by said clamp (1) with the retention portions (6) of said inserts (5) inserted in the corresponding said first milled grooves (101).