Fundamental Study on Weld Formation Phenomena of High Speed Lap Seam Welding (4 th Report)

Current Path and its Area at Weld Interface

Abstract

The current path area at the weld interface is measured to elucidate the current path in the plate. The results obtained are as follows.
(1) Length between the start point of current flow and the center of electrodes S_i decreases with increased welding speed and increased welding current.
(2) Length between the end point of current flow and the center of electrodes E_i at I_min increases as welding speed and welding current increase.
(3) With increased welding speed, the length of current path area Li at Imin increases slightly above 1.2 mm in plate thickness and decreases slightly below 0.5 mm in plate thickness.
(4) Si, Ei and Li decrease with decreased electrode force.
(5) The width of current path area at the weld interface W_i decreases with increased welding speed and decreased electrode force.
(6) In high speed seam welding, current path area of the weld interface falls behind and is smaller than that of the contact surface.
(7) Welding current is guessed to flow uniformly in the direction of welding line and width within the current path area.
(8) The average current density at the weld interface δ_i becomes smaller than the current density δ_c, given by the equation (2) above the welding speed of 6.5, 4, and 2.5 m/min for plate thickness of 0.5, 1.2 and 1.6 mm respectively.