Machine tool with automatic tool change

In a machine tool with an automatic tool change function having a tool spindle rotatably supported and capable of receiving a tool at one end thereof, the improvement comprising:

• tool support means for rotatably supporting at least one tool to selectively insert and remove the same into and from said tool spindle;
• a movable key movably guided in said spindle and having a width smaller than that of a key-way formed on said tool;
• means for urging said movable key beyond the one end of said spindle;
• first control means responsive to a tool change command for rotating said spindle at a predetermined speed permitting key-engagement;
• operating means for causing relative movement between said tool support means and said spindle for a tool change operation with said spindle being rotated at the predetermined speed;
• detecting means for detecting movement of said movable key to confirm engagement of said movable key with the key-way of said tool;
• clamp means responsive to said detecting means for clamping said tool inserted into said spindle;
• second control means for rendering said first control means inoperative and for rotating said spindle at a commanded machining speed after said tool is clamped relative to said spindle.