| 摘要 |
PURPOSE:To assure the quality of a weld zone at all times through adaptation to change in the contact state between materials to be welded and electrode crushing conditions by controlling the pressurizing force between electrodes and welding current in such a way that the voltage simultaneously with the resistance between the electrodes are made coincident to respective reference curves during conduction of welding current. CONSTITUTION:Welding current is conducted from the secondary side of a transformer 4 between electrodes 2a, and 2b grasping materials 1a, 1b to be welded by pressure, and a circuit 5 sends the voltage between the electrodes momentarily. On the other hand, a circuit 7 sends welding current momentarily, and a circuit 9 detects the resistance between the electrodes. This is compared with the value of a circuit 10, and the pressurizing force of a cylinder 3 is controlled, whereby the resistance between th electrodes is so changed as to coincide with a reference resistance curve. At the same time, the value of the circuit 5 is compared with the value of a circuit 21, and the voltage between the electrodes is changed in conformity with a reference voltage curve with a circuit 15. The voltage of an electric power source 14 is compared with the value of a circuit 23 momentarily, and the value of the circuit 24 is corrected with a circuit 26 and a firing phase angle is controlled with circuit 15, so that reference welding current is maintained constant despite fluctuations of the source voltage. |
