Safety device for a rotational feed axis

A safety device of a rotational feed axis of a machine tool for preventing unintentional rotation of the rotational feed axis, comprising:

• a rotary table provided on a rotational shaft of a power transmission mechanism for the rotational feed axis and configured to mount a workpiece thereon;
• an annular member concentrically attached to the rotary table;
• a plurality of openings defined in the annular member to open in a direction of a rotational feed axis of the rotary table, and disposed at equal intervals in a circumferential direction of the annular member;
• and
• at least two pins, disposed away from each other in the circumferential direction of the annular member in a housing for the rotational feed axis, the at least two pins being extendable and retractable so as to be received in the openings of the annular member;
• wherein the at least two pins are disposed so that an angle formed by two lines extending between the center of the annular member and corresponding centers of two adjacent openings and an angle formed by two lines extending between the center of the annular member and corresponding centers of two adjacent pins do not coincide with each other, whereby at least one of the pins can be received in the openings for any rotational position of the rotational shaft when the at least two pins are extended simultaneously.