| 摘要 |
PURPOSE:To enable the formation of a welding nugget having stable quality by increasing successively an electrical welding current together with conduction time and stopping the current application upon completion of the formation of the prescribed welding nugget thereby making the device easily adaptable to various kinds of disturbances. CONSTITUTION:The output of a nugget detector 1 which monitors the formation of the welding nugget in spot welding by resistance welding is converted to quantity of electricity with a converter 2. Said quantity of electricity is compared with the quantity of electricity upon completion of an adequate nugget applied from a setter 3 in a comparator 4, and when both quantities of electricity attain equal, a stop signal for current application is transmitted to a conduction time controller 5, which interrupts the power feed to a welding transformer 7 with an electronic switch 6, thereby stopping the conduction of the welding current. On the other hand, a current controller 8 servocontrols the welding current by the feedback input from a current detector 10 and a function voltage curve including a straight line to increase the welding current upon lapse of the weld time obtained from a function voltage transmitter 9. |
