| 摘要 |
Disclosed is a welding-current adjusting device for a shielded arc welding machine which resolves a problem, which is caused by an electrode and a base material sticking to each other, by controlling generation of arc by detecting a short state of the electrode and which is improved to smoothly generate the arc. The present invention provides the welding-current adjusting device for a shielded arc welding machine which comprises: a current-adjusting resistor circuit for changing and providing a current-adjusting resistance value corresponding to short and non-short states; a current-adjusting circuit for outputting adjusted current according to the current-adjusting resistance value; a current-sensing resistance circuit for changing and providing a current-sensing resistance value corresponding to a short impulse state, the short state, a no-load impulse state and a welded state; a determination unit for providing an adjusting signal to select the current-adjusting resistance value of the current-adjusting resistance circuit and the current- sensing resistance value of the current-sensing resistance circuit according a level of output voltage; a current-sustaining switching circuit for sustaining and outputting current by sustaining and switching the current by getting a feedback of output current; a current-sensing circuit for outputting the current output from the current-sustaining switching circuit as sensed current according to the current-sensing resistance value; a PWM circuit for outputting a pulse signal corresponding to an average value of the adjusted current and the sensed current; and an output circuit outputting welding current depending on the pulse signal. [Reference numerals] (12) Current-adjusting circuit; (16) Load determination unit; (18) Short impulse timer; (19) No-load impulse timer; (20) Current-sustaining switching circuit; (22) Current-sensing circuit; (24) PWM circuit; (26) Output circuit; (AA) Feedback current. |
