Control method and apparatus for automatic welding machine

• US 4,984,171 A
• Filed: 02/21/1989
• Issued: 01/08/1991
• Est. Priority Date: 02/23/1988
• Status: Expired due to Fees

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Tsujii, Gen
• Primary Examiner(s): Smith, Jerry
• Assistant Examiner(s): TRAMMELL, JAMES P
• Application Number:
  US07/313,000
• Time in Patent Office: 686 Days
• Field of Search: 364/477, 219/110, 219/109, 219/138, 219/86.1-86.41, 901/31, 901/33, 901/41, 901/42
• US Class Current: 700/212
• CPC Class Codes: B23K 11/253 the measured parameter being a displacement or a position

Abstract

Change in outputs from a pair of distance sensors mounted on a pair of gun arms is monitored to determine whether or not the gun arms have started to move toward opening to activate the robot carrying the welding gun. If no change in output occurs in either sensor when an instruction is given to open (generally because a fusion weld of the electrode to the workpiece has occurred), an alarm is activated and the robot is not.

Claims

1. A control method for an automatic welding machine in which a welding gun is moved by a robot successively to a plurality of welding spots on a workpiece in order to carry out spot welding, said control method comprising the steps of:

detecting by a pair of distance sensors the respective movements of a pair of gun arms of the welding gun;

determining from changes in outputs of the respective distance sensors at the time when the welding gun is being opened after completion of the welding at each welding spot whether or not each gun arm has started to move toward its opening side; and

operating the robot when it is confirmed that the gun arms have both started moving toward their opening sides.

2. A control apparatus for an automatic welding machine in which a welding gun is moved by a robot successively to a plurality of welding spots on a workpiece in order to carry out spot welding, said gun having a pair of gun arms, said control apparatus comprising:

a pair of distance sensors detecting the respective movements of each of the pair of gun arms of the welding gun;

a discrimination means which operates, at the time when the welding gun is being opened after completion of the welding at each welding spot, to store outputs of said distance sensors and determine from changes in said outputs whether or not each gun arm has started to move toward its opening side; and

a signal generation means which outputs an instruction signal for operation of the robot when it is confirmed that both gun arms have started to move toward their opening sides and which outputs a fusion-weld-of-electrode-tip signal when at least one of the gun arms has not started to move toward its opening side even after the lapse of a predetermined time.