Steel-frame cutting method and device

A cutting apparatus for cutting a steel frame along a cutting surface perpendicular to a longitudinal direction of the steel frame, the cutting apparatus comprising:

• a first gripping member and a second gripping member that grip the steel frame in a gripping direction along the cutting surface;
• a gripping drive unit that moves the first gripping member and the second gripping member in the gripping direction to make the first gripping member and the second gripping member grip and release the steel frame;
• a cutting torch having a fire port and being capable of supplying a flame and oxygen for oxidation of the steel frame to the steel frame from the fire port;
• a torch feed unit capable of holding the cutting torch at a position apart from the steel frame in a direction along the cutting surface and in a specific posture where the fire port of the cutting torch is directed to the steel frame and moving the cutting torch in a first feed direction which is a direction along the cutting surface and perpendicular to a supply direction in which the flame and the oxygen are supplied from the fire port and in a second feed direction opposite to the first feed direction while maintaining the specific posture;
• a gripping position detector that detects respective positions of the first gripping member and the second gripping member;
• a position setting section that sets a cutting start position to a position of a first end of the cutting surface or to a position on an outer side of the first end with respect to the gripping direction based on the position of the first gripping member and sets a first cutting end position to a position of a second end of the cutting surface opposite to the cutting start position across the cutting surface or to a position on an outer side of the second end with respect to the gripping direction based on the position of the second gripping member;
• and
• a cutting control section that controls respective operations of the cutting torch and the torch feed unit so as to move the cutting torch in the first feed direction from the cutting start position to the first cutting end position, while making a flame be applied from the fire port of the cutting torch in the supply direction along the cutting surface and making oxygen for oxidation of the steel frame be supplied, and so as to stop the cutting torch at the first cutting end position and thereafter move the cutting torch from the first cutting end position in the second feed direction opposite to the first feed direction.