| 摘要 |
PURPOSE:To obtain an electric welding machine that is able to prevent destruction of a welded zone due to abnormal heat generation of the welding tip, by controlling welding current or power source directly by a safe operation securing circuit basing on a detecting signal of a thermocouple attached to the welding tip. CONSTITUTION:In an electric welding machine that welds electronic parts in which an AC power source 16 and a DC power source 17 are connected to a welding tip 6 consisting of a heating unit of Mo etc. through a breaker 15 and a thyristor 14 and welding current is controlled through a signal amplifier circuit 35, a temperature control circuit 31, an energizing circuit 32 etc. using a detection signal of a thermocouple 7 attached to the welding tip, if electromotive force Vt of the thermocouple 7 is above a set value, the breaker 15 is operated by an Hi comparator 20 through a flip flop circuit 22 to cut off the power source. When Vt is below the set value, it is detected by a Low comparator 21, and energizing is stopped by controlling the thyristor 14 through a flip flop circuit 23, an AND circuit 27, an energizing timing control circuit 28 and an energizing control circuit 32. |
