| 摘要 |
PURPOSE:To assure a required rate of expansion by a feedback controlling of a power source and to obtain a weld zone having high quality in spot welding by measuring the amt. of expansion of an welding object by melting, and stopping the conduction of electricity when the measured value is above a reference value and conducting electricity further if the value is below the reference value. CONSTITUTION:A chip 3 is lowered by a cylinder 6, an object to be welded 2 is put between the chips 3 and 4, and electricity is conducted thereto. Then, the weld zone 9a of the object 2 melts and expands gradually from the inside to (l) from the initial size l0. The change in the position of the chip 3 is measured from the rate of expansion l-l0=DELTAl by a displacement converter 7, and the rate DELTAl of expansion for the required size is maintained. |
