Electrospindle with a tool exchanging device

An electrospindle device (100) comprising:

• a casing (45);
• a toolholder support element (5) rotatably mounted to the casing (45), the toolholder support element (5) including plural toolholders (3), each of said toolholders (3) holding a respective machining tool (40), each of said toolholders (3) having a respective conical portion with a respective narrowed section (69), the toolholder support element (5) having a first end located adjacent an outer surface of the casing (45) and an opposite second end facing away from the casing, the toolholder support element (5) having an outer surface extending from the first end to the second end, the first end of the toolholder support element (5) having a width greater than a width of the second end, each of said toolholders (3) extending through the outer surface of the toolholder support element (5) in a region between the first end and the second end;
• at least one electrospindle (2) extending about a vertical axis (X-X′), said at least one electrospindle (2) located at least partially within the casing (45), the at least one electrospindle (2) comprising
• i) a rotating shaft (39) that rotates for transmitting motion, the rotating shaft (39) comprising an engagement portion (6) with a conical seat that receives the conical portion of a selected one of said toolholders (3);
• (ii) a tie rod (99) that is provided within the rotating shaft (39), and that includes a head end having an engagement portion including a conical outer surface (51), and
• (iii) a locking device comprising a cylindrical gripper (50) associated with the head end of the tie rod (99), the cylindrical gripper (50) having a conical inner surface corresponding to the conical outer surface (51) of the engagement portion of the tie rod (99), the cylindrical gripper having an outer surface (52) with an adjustable outer diameter,
• wherein the head end of the tie rod (99) is slidable along the vertical axis (X-X′) relative to the cylindrical gripper (50) so as to cause the outer diameter of the cylindrical gripper (50) to be increased or reduced, and
• wherein the locking device is operable to selectively lock the selected one of the toolholders (3) to the rotating shaft (39) so that, when the selected one of the toolholders (3) is locked to the rotating shaft (39), the rotating shaft (39) directly rotates the selected one of the toolholders (3) and the corresponding held machining tool (40);
• the electro spindle device (100) further comprising
• a device for rotating the toolholder support element (5) such that an outer periphery of the first end of the toolholder support element (5) rotates, adjacent to and along an inner periphery of the casing (45) via a friction reducing element (73) connecting the outer periphery of the first end of the toolholder support element (5) to the inner periphery of the casing (45), wherein operation of the at least one device for rotating the toolholder support element (5) brings the selected one of said toolholders (3) into vertical alignment with the engagement portion (6) of the rotating shaft;
• at least one translation unit for translating the toolholder support element (5) along the vertical axis (X-X′) between
• i) an operating position where at least a portion of the selected one of the toolholders (3) is engaged and locked, via the locking device (48), to said engagement portion (6) of the rotating shaft (39), and
• ii) a tool change position where the selected one of the toolholders (3) lies outside the engagement portion (6) of the rotating shaft (39),
• wherein operation of the device for rotating the toolholder support element (5) rotates the toolholder support element (5) to bring the selected one of said toolholders (3) into vertical alignment with the engagement portion (6) of the rotating shaft (39),
• wherein the at least one translation unit is operable to move the toolholder support element (5) from the tool change position to the operating position, and, while the toolholder support element (5) is at the operating position, the tie rod (99) is movable to an upper position so as to expand the outer surface (52) of the cylindrical gripper (50) to engage the outer surface (52) of the cylindrical gripper (50) with the narrowed section (69) of the selected one of the toolholders (3), thus locking the selected one of said toolholders (3) relative to the rotating shaft (39), thereby engaging the rotating shaft (39) with the selected one of said toolholders (3), making said selected one of said toolholders (3) and the corresponding held machining tool (40) directly rotatably actuated by said rotating shaft (39), and
• wherein the at least one translation unit is further operable to move the toolholder support element (5) from the operating position to the tool change position, and, while the toolholder support element (5) is at the tool change position, the tie rod (99) is movable from the upper position to a lower position where the outer surface (52) of the cylindrical gripper (50) does not engage the narrowed section (69) of the conical portion of the selected one of the toolholders (3), thereby disengaging the rotating shaft (39) from the selected one of the toolholders (3).