WELDING DEVICE

To solve the problem of requiring a dedicated detection line for detecting voltage between a welding wire tip and a base material in order to detect a constriction.SOLUTION: A welding device comprises a current difference circuit ER for detecting a difference between a command value Ir of a current command circuit IR and a detection value Id of a current detection circuit ID, and a current error amplification circuit EI for amplifying an error between signals of them. The welding device starts detection of a constriction when an output of the current error amplification circuit EI has become constant after a welding current Iw during a short-circuit period reached a constant peak current, holds the output of the current error amplification unit EI at that point in a current error holding circuit HD, and switches an error amplification signal Ea for controlling an output of a welding power source PM from an output value Ei of the current error amplification circuit EI to an output value Hd of a current error holding part HD minus an output value Er of the current difference circuit ER.SELECTED DRAWING: Figure 1 【課題】くびれを検出するには、溶接ワイヤ先端と母材間の電圧を検出するための専用の検出線を必要とする課題がある。【解決手段】電流指令回路ＩＲの指令値Ｉｒと電流検出回路ＩＤの検出値Ｉｄの差分を検出する電流差分回路ＥＲと、同じく両者の信号の誤差増幅を行う電流誤差増幅回路ＥＩと、短絡期間中の溶接電流Ｉｗが前記一定のピーク電流に達した後、電流誤差増幅回路ＥＩの出力が一定となった時点で、くびれの検出を開始するとともに、その時点の電流誤差増幅部ＥＩの出力を電流誤差保持回路ＨＤにて保持し、溶接電源ＰＭの出力制御を行う誤差増幅信号Ｅａを、電流誤差増幅回路ＥＩの出力値Ｅｉから、電流誤差保持部ＨＤの出力値Ｈｄから電流差分回路ＥＲの出力値Ｅｒを減算した値に切り替える。【選択図】 図１