Door device of machine tool and machine tool

A machine tool comprising:

• a machining device configured to machine a workpiece;
• a workpiece support device configured to support the workpiece;
• a housing surrounding the machining device and the workpiece support device and having an opening;
• and
• a door device comprising:
• a door provided to be slidable between a first position and a second position, the door at the first position being configured to close an opening in a housing of the machine tool, the door at the second position being configured to fully open the opening;
• an air cylinder having a first air chamber to which air is configured to be supplied so as to apply a first assist force to the door in a first direction from the first position toward the second position;
• a fluid passage having a first fluid passage connecting the first air chamber and an air supply source;
• a switch valve provided at the fluid passage;
• and
• a manipulation switch configured to switch a state of the switch valve between a first state and a second state, the door, in the first state, being movable in the first direction and a second direction opposite to the first direction without the first assist force, the first assist force being applied to the door in the second state.