Proper Heat Input Control Methods Relevant to Different Drooping Characteristics of Power Sources : Study on Projection Welding (2nd Report)

概要

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Based on the previous work, the regions of welding conditions were arranged on the plane of the electrode force and the weld current for the power sources of drooping characteristics with different no-load voltages such as 3.3V and 6.3V. The region of proper welding condition was estimated taking the indentation and the tensile shear strength into consideration. The indentation was found to be seriously affected by the initial splash during collapse of projection in the case of using the power source with no-load voltage of 6.3V and by the splash in the latter half weld time after collapse of projection in the case of using the power source with 3.3V. Especially, the expulsive initial splash was responsible for the deformation of nugget shape, unstable tensile shear strength with a large amount of scatter and unstable failure of welds in the tear or the shear fracture at the rate of about 50%. The tensile shear strength tended toward saturation immediately after the occurrence of a splash in the latter half weld time. In order to suppress these splashes and overcome these faults of the welds the adaptive electrode force changing up slope was used when the power source with no-load voltage of 3.3V was operated, and the stepwise control for the weld current at the initial weld time was proposed when the power source with no-load voltage of 6.3V was operated.
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