TIG WELDER AND CONTROL METHOD THEREOF

PROBLEM TO BE SOLVED: To provide a touch start system TIG welder and a control method thereof capable of highly accurate TIG welding even to a small-sized welding object.SOLUTION: An electrode 1 is controlled for descent in a state of not impressing welding voltage between the tip of the electrode 1 and a work 2, and when detecting contact between the tip of the electrode 1 and the work 2 by a touch start detection circuit 30, the electrode 1 is controlled for ascent in a state of making a separation detection current flow from a touch start TIG welding power source 10 between the tip of the electrode 1 and the work 2, and when voltage between the tip of the electrode 1 and the work 2 becomes separation detection reference voltage, it is detected that the tip of the electrode 1 separates from the work 2, after detecting that the tip of the electrode 1 separates from the work 2, the electrode 1 is relatively positioned, and a separation detection current from the touch start TIG welding power source 10 is switched to a regular electric conduction current in relative positioning after completing the relative positioning or before completing the relative positioning.SELECTED DRAWING: Figure 1 【課題】小型の被溶接物に対しても高精度なＴＩＧ溶接を可能なタッチスタート方式のＴＩＧ溶接装置およびその制御方法を提供する。【解決手段】電極１の先端とワーク２との間に溶接電圧を印加しない状態で電極１を下降制御し、電極１の先端とワーク２との接触をタッチスタート検出回路３０により検出すると、電極１の先端とワーク２との間にタッチスタートＴＩＧ溶接電源１０から離れ検出電流を流した状態で電極１を上昇制御し、電極１の先端とワーク２との間の電圧が離れ検出参照電圧になったときに、電極１の先端がワーク２から離れたと検出し、電極１の先端がワーク２から離れたと検出した後、電極１の相対位置決めを行って、該相対位置決め完了後若しくは該相対位置決め完了前の該相対位置決め中にタッチスタートＴＩＧ溶接電源１０からの離れ検出電流を本通電電流に切り換える。【選択図】図１