Spindle device

A spindle device for supplying an air for cleaning and a coolant for cooling and lubricating, comprising:

• a tool holder (11) having a coolant passage (22) through which a coolant is supplied;
• a spindle (10) having a support portion (26) formed at a front end thereof for accepting the tool holder (11);
• a drawing bolt (25) having a through-hole for supplying air and a coolant and movably arranged in the spindle (10) for clamping and unclamping the tool holder (11) accepted on the support portion (26) of the spindle (10);
• a pull stud (12) attached on the tool holder (11), said pull stud comprising a valve seat;
• and
• a valve (13) comprising a valve member cooperating with said valve seat, said valve member having a first flow passage, said valve seat having a second flow passage, said first and second flow passages forming a bypass to provide fluid communication from the through-hole to a discharge path between the tool holder and the spindle when said valve is temporarily closed by seating the valve member against the valve seat,
• the valve (13) being located in association with the coolant passage (22) and the through-hole, the valve (13) being so constructed as to open and close according to the movement of the drawing bolt (25) in such a manner that the valve (13) opens so as to connect the through-hole to the coolant passage (22) when the tool holder (11) is clamped, and the valve (13) temporarily closes so as to shut the connection between the through-hole and the coolant passage (22) when the tool holder (11) is unclamped,
• wherein a coolant can be supplied from the through-hole to the coolant passage (22) via the valve (13) when the tool holder (11) is clamped, and air can be supplied from the through-hole through said bypass and discharge path when the tool holder (11) is unclamped.