Spindle device of machine tool

A spindle device of a machine tool comprising:

• a spindle (2);
• a tool holder (25) mechanically detachably fixed on a tip of said spindle (2) by clamping means (KR) having a center, a pull stud (31) being connected to said tool holder;
• a longitudinal guiding bar member (16) located in the center of said clamping means (KR);
• a slipping prevention ring member (21) mounted on said longitudinal guiding bar member (16);
• an extension passage member (20) inserted slidably through said slipping prevention ring member (21), the extension passage member defining a cylinder having an extension passage (101) and a projecting tip;
• and
• a flange formed on an end of said extension passage member (20) distal to said tool-holder to prevent, by engaging with the slipping prevention ring member (21), said extension passage member from slipping,
• the longitudinal guiding bar member having in a central hole, in order from an end distal to said tool holder to an opposite end, a gas-liquid passage (17), a lubricating coolant atomizing means (18) comprising an atomizing nozzle (23) and a compressed air supplying valve (24), a compression spring (19) and the extension passage member (20),
• wherein said compressed air supplying valve (24) is pressed toward said atomizing nozzle (23) by said compression spring (19), and said extension passage member (20) is pressed toward the pull-stud (31) so that its tip always projects from a tip of said slipping prevention ring member (21);
• and
• said extension passage is in fluid communication with an in-holder spray lubricating coolant passage (102) formed in a center of said tool holder (25).