Rotary table device for working machine

A rotary table device for a working machine, including:

• a rotary shaft having one end side to which a rotary body including a table to which a workpiece is attached is fixed;
• a frame configured to rotatably support the rotary shaft via a bearing within an accommodation hole, the rotary shaft being rotationally driven by a drive device;
• and an air seal mechanism configured to supply air from an air supply port formed in the frame in order to blow out the air from a gap between a surface of the rotary body and a surface of the frame facing each other in an axis line direction of the rotary shaft, the rotary table device further comprising:
• an annular accommodation groove opening to the gap and formed in the frame coaxially with the rotary shaft;
• a sealing piston accommodated to be slidable in the axis line direction in the accommodation groove;
• an elastic member for urging the sealing piston toward the rotary body;
• a protrusion portion provided to the frame in a form of protruding in a radial direction of the rotary shaft from a peripheral edge of the accommodation groove toward a center of the accommodation groove so as to cover a part of the opening of the accommodation groove over an entire circumference;
• a pressure chamber defined by the protrusion portion and the sealing piston with respect to the axis line direction;
• and
• a supply device configured to supply a working fluid with a pressure sufficient to displace the sealing piston toward a bottom surface of the accommodation groove against urging of the elastic member.