Vertical machining center

A vertical machining center comprising:

• a table;
• a tool spindle provided to be relatively movable with respect to the table in a first direction, a second direction, and a third direction;
• an angle tool holder attachable to and detachable from the tool spindle, the angle tool holder comprising:
• a shank to be inserted into the tool spindle, the shank having a shank axis and being rotatable around the shank axis;
• an attachment spindle having a spindle axis perpendicular to the shank axis and being rotatable around the spindle axis;
• a housing rotatably supporting the shank and the attachment spindle and including an internal transmission mechanism to transmit drive force from the shank to the attachment spindle;
• a collet disposed on the attachment spindle to clamp a tool;
• a draw bar disposed in the attachment spindle to move forward and backward along the spindle axis to clamp and unclamp the collet;
• and
• a spring mechanism to press the draw bar along the spindle axis so that the collet clamps the tool;
• a tool unclamping operation device to unclamp the tool, the tool unclamping operation device comprising:
• an angle tool holder rest on which the angle tool holder is to be placed;
• a hydraulic piston to press the draw bar of the angle tool holder along the spindle axis;
• and
• a restrictor disposed on the angle tool holder rest to restrict a portion of the angle tool holder and to receive force in a direction of the spindle axis which is generated in a case where the hydraulic piston presses the draw bar, the restrictor being provided so that a point of application of the force that the restrictor receives is positioned on a plane which is parallel to the shank axis and contains the spindle axis;
• and
• a tool changer to change the tool attached to the angle tool holder with the tool unclamping operation device.