TOOL-HOLDER UNIT OF A MACHINE FOR MACHINING BLOCK OR SLAB MATERIALS， MACHINE INCLUDING SUCH UNIT AND METHOD FOR MACHINING BLOCK OR SLAB MATERIALS

The invention relates to a tool-holder unit (10) of a machine (100) for machining block or slab materials (200)， the tool-holder unit (10) being moveable above a working plane (102) of said machine (100) on which the block or slab material (200) to be machined is laid， wherein the tool-holder unit (10) comprises: a spindle (12) on which a circular blade (11) can be mounted， and a coupling assembly (61) for removably coupling a second machining tool (28， 128) to a front free end (12a) of the spindle (12)， comprising: a) a tool-holder (50) associated to the second machining tool (28， 128); b) at least one mechanical coupling device (63) provided with elements cooperating in abutment relationship (58， 68) to make the tool-holder (50) and the spindle (12) rotationally integral with each other; and c) a first axial locking element of the tool-holder (50) of the magnetic type， configured to removably lock in translation and in a substantially axial direction said tool-holder (50) on the spindle (12)， d) a substantially cylindrical shank (57a) extending from said free end of the tool-holder (50); e) a substantially cylindrical housing seat (67a) of said shank (57a)， axially positioned in said spindle (12) or， if present， in a tool-holder coupling element (60) associated to the front free end (12a) of the spindle (12); and f) at least a second axial locking element (70) of the tool-holder (50)， configured to removably lock in translation and in a substantially axial direction the tool-holder (50) in the spindle (12)， the axial locking element (70) being translationally movable in the radial direction to removably lock the shank (57a) in the respective housing seat (67a).