PURPOSE: To provide a hole to the circumferential wall of a pipe and to cut off a plate pipe to a prescribed shape by rotating twice a swiveling arm with one turn of a revolving shaft to bring the end of the swiveling arm into contact with an inclined plate thereby sliding a slider.

CONSTITUTION: The forward and backward movement of pushing out a slider 2 in the midway of turning half-round 180° from the time when a swiveling arm 20 starts rotating and pulling back the slider 2 in the midway of turning remaining half-round 180° is repeated. Melt cutting of the circumferential wall of a pipe B by a nozzle A is ended by one turn of the 2nd arm 24 during this time to open a hole to the pipe B. The end of the 1st arm 23 is then supported to a connecting member 22 and the nozzle A is set to the 1st arm 23. A plate pipe B' is set to a supporting base 59 and the nozzle A is positioned on the outside at the end of the pipe B'. A revolving shaft 6 is revolved by a motor 8 to move forward and backward the slider 2 by the arm 20 and an inclined plate 13, thereby forming cut-out at the pipe B' end. The pipe B' is fixed to the pipe B by welding the same tightly to the edge of the hole in the cut-out part.