Machine tool

A machine tool which machines a workpiece in a machining chamber using a tool selected from a plurality of tools held in a tool holding chamber, the machine tool comprising:

• an arm for exchanging the tool between a spindle in the machining chamber and a secondary tool standby position in the tool holding chamber,
• a shutter provided in an opening defined in a wall partitioning the machining chamber and the tool holding chamber, the shutter being movable between a fully open position and a fully closed position,
• a first motor for opening and closing the shutter,
• a shutter position detector which is capable of detecting a position of the shutter over an entire range between the fully open position and the fully closed position,
• a storage device in which predetermined positions of the shutter are stored in association with predetermined motions of the arm, and
• a controller which is configured to execute the predetermined motions of the arm based on the position of the shutter detected by the shutter position detector and based on the predetermined positions of the shutter stored in the storage device, wherein
• the controller is programmed to execute a predetermined motion of the arm in which the arm incurs rotational motion about a rotation axis, which rotational motion is from an arm standby position to a tool engagement position when the shutter position detector detects that the shutter has moved from the fully closed position to a first predetermined position of the predetermined positions at which the shutter is partially opened, and
• the controller is programmed to execute a predetermined motion of the arm in which the arm incurs translational motion from a retreat position to a forward position in a direction that extends parallel to the rotation axis of the arm when the shutter position detector detects that the shutter has moved from the first predetermined position into a second predetermined position of the predetermined positions at which the shutter is further opened than when the shutter is disposed in the first predetermined position.