Method for controlling arc welding and arc welding device

Abstract

Disclosed is a method for controlling arc welding where an arc is generated between a welding wire as a consumable electrode and an object to be welded. The method includes: keeping a wire feed speed at a predetermined constant speed in a steady-state welding period; and at a time point when welding termination is ordered, either switching the wire feed speed from the predetermined constant speed to a wire feed speed at which the welding wire is fed in alternating forward and backward directions, or decreasing the wire feed speed from the predetermined constant speed with time, and then switching the wire feed speed to the wire feed speed at which the welding wire is fed in alternating forward and backward directions at a time point when a predetermined time period has passed since when welding termination was ordered.

1 - 11 . (canceled) 
     
     
         12 . A arc welding device for performing welding by alternating generation of an arc and a short circuit between a welding wire as a consumable electrode and an object to be welded, the arc welding device comprising:
 a switching unit for controlling a welding output;   a drive unit for controlling the switching unit;   a welding current detector for detecting a welding current;   a welding voltage detector for detecting a welding voltage;   a short-circuit/arc detector for detecting whether welding is in a short-circuit state or in an arc state based on at least one of an output of the welding voltage detector and an output of the welding current detector;   a short-circuit controller for outputting a welding-output control signal for a short-circuit period to the drive unit upon receiving a signal indicating that the welding is in the short-circuit state from the short-circuit/arc detector;   an arc controller for outputting a welding-output control signal for an arc period to the drive unit upon receiving a signal indicating that the welding is in the arc state from the short-circuit/arc detector;   a wire feed speed controller for controlling a wire feed speed based on an output of the short-circuit/arc detector;   a welding condition setting unit for setting welding conditions including programmed current and programmed voltage; and   an end-of-welding ordering unit for ordering termination of welding, wherein   in a steady-state welding period, the wire feed speed controller is configured to controls the wire feed speed to be a predetermined constant speed, and   at a first time point when a welding termination is ordered:   
       the wire feed speed controller is configured to switch the wire feed speed from the predetermined constant speed to a wire feed speed at which the welding wire is fed in alternately repeating forward and backward directions,
 wherein in an end-of-welding period lasting from the first time point when the welding termination is ordered until a second time point at which the welding output is turned off, 
 an average feed speed of the wire feed speed at which the welding wire is fed in alternately repeating forward and backward directions gradually decreases while the welding wire is fed a plurality of times in the alternately repeating the forward and the backward directions, or 
 the wire feed speed controller is configured to decrease the wire feed speed from the predetermined constant speed with time, and then 
 switch the wire feed speed to the wire feed speed at which the welding wire is fed in alternately repeating forward and backward directions at a third time point when a predetermined time period has passed from the first time point when welding termination was ordered, 
 wherein in a period lasting from the third time point until the second time point at which the welding output is turned off, 
 the average feed speed of the wire feed speed at which the welding wire is fed in alternately repeating forward and backward directions gradually decreases while the welding wire is fed a plurality of times in the alternately repeating the forward and the backward directions. 
 
     
     
         13 . The arc welding device of  claim 12 , further comprising:
 an industrial robot including a manipulator and a robot control device to control an operation of the manipulator; and   a welding power source, wherein   the industrial robot includes the welding condition setting unit and the end-of-welding ordering unit; and   the welding power source includes the switching unit, the drive unit, the welding current detector, the welding voltage detector, the short-circuit/arc detector, the short-circuit controller, the arc controller, and the wire feed speed controller.   
     
     
         14 . The arc welding device of  claim 13 , wherein
 the welding power source is disposed in the robot control device.   
     
     
         15 . The arc welding device of claim  1  further comprising a crater condition ordering unit for ordering performance of a welding crater treatment, the welding crater treatment being a treatment to fill in a crater, wherein
 the wire feed speed controller switches the wire feed speed from the predetermined constant speed to a wire feed speed at which the wire is fed in alternating forward and backward directions at the time point when the welding crater treatment is ordered.