CONTROL METHOD OF PIPE ROTATION SPEED IN BUTT WELDING OF PIPE PERIPHERY

PURPOSE:To control automatically the peripheral speed of welding point, to make welding conditions constant and to stabilize the quality by measuring the position of welding torch by fitting rotary encoder on the arm to move the welding torch and by performing an operation based on the signal thereof. CONSTITUTION:A pulse is transmitted to an arithmetic processing unit 7 by measuring always by a rotary encoder 3 the length R from the center of a pipe 6 upto the tip of a welding torch 1 namely upto a welding point 11. The arithmetic processing unit 7 calculates the peripheral speed of the welding point 11 based on the pulse thereof and transmits to a rotary motor 4 the signal to indicate the number of revolutions of the rotary motor 4 so as the make a proper peripheral speed by comparing the calculated value with the proper peripheral speed. By making the peripheral speed at the welding point 11 constant as per the above, a weld can be performed stably under the fixed welding conditions irrespective of the size of the pipe 6, which contributes greatly to the promotion of unmanned welding.