Pipe cutting machine

A stationary or traveling pipe cutting machine that cuts a pipe at a right angle to the center line of the pipe, comprising:

• rotary blades in a pair, with a plane at a right angle to the center line of the pipe to be cut defined as an x-y plane and the center of the pipe defined as a coordinate origin, the rotary blades being arranged to face each other on both sides of a y axis in such a manner that blade edges of the rotary blades overlap each other in the direction of an x axis;
• a straightforward driving mechanism that drives the rotary blades in the pair straightforward in opposite directions of a y-axis direction so as to make the rotary blades in the pair pass each other on the x axis and in the vicinity of the x axis;
• and
• a power direction conversion mechanism that moves at least one of the rotary blades in the pair in an outward direction in which the at least one of the rotary blades in the pair gets farther from the y axis for avoiding interference between the blade edges when the rotary blades in the pair pass each other on the x axis and in the vicinity of the x axis, wherein
• the power direction conversion mechanism comprises:
• a blade biasing mechanism that applies biasing force to the at least one of the rotary blades in the pair in an inward direction in which the at least one of the rotary blades gets closer to the y axis and holds the biased rotary blade at an inner movement limit;
• and
• a guide mechanism that causes the at least one of the rotary blades in the pair to make an outward retreating movement in the outward direction against the biasing force when the rotary blades in the pair pass each other on the x axis and in the vicinity of the x axis.