| 摘要 |
PURPOSE:To perform welding of always excellent welding quality in the stage of welding with a resistance welding machine by measuring the max. inter-electrode voltage and electric resistance after start of electrical conduction and the inter-electrode voltage and resistance upon ending of the electrical conduction and adjusting automatically the welding current by the increase and decrease in the calculated value of the differential voltage and differential resistance thereof. CONSTITUTION:A means for measuring the max. inter-electrode voltage value or electric resistance value upon lapse of a prescribed time from the start of electrical conduction and the inter-electrode voltage value or electric resistance value upon ending of the electrical conduction, a means for calculating said values, and a means for increasing or decreasing the welding current in accordance with the differential voltage are provided. The welding current of an adequate initial value determined by base current IB flows through an electrode tip 3 to a work 5 in the stage of starting the use of the tip 3. The output of a comparator 16 in this stage is zero and since the count value of an up-down counter 18 is zero as well, correction current Ialpha is not outputted from a correction current setter 19. When the differential voltage value decreases down to a prescribed value or below on the consumption of the tip 3, an up-signal is outputted from the comparator 16, and the counter 18 counts up. Then the setter 19 outputs the correction current Ialpha corresponding to the count value and the welding current increases in accordance with said current and attains the adequate value corresponding to the consumed electrode. |
