| 摘要 |
<p>PURPOSE:To facilitate the discrimination of a welding portion by providing a peel-off portion of a protective tape at a position corresponding to the welding portion. CONSTITUTION:A protective tape 3 is stuck to the surface side of a metal plate 1. In this case, the protective tape 3 at a position corresponding to a welding portion 23 connecting the metal plates 1 together is peeled off 24 over a range (1), thereby the surface of the metal plate 1 is exposed. Part of the protective tape 3 is just needed to be cut off prior to the welding to provide the peel-off portion 24. Accordingly, since the metal plate 1 is exposed over a range (1), the selection of defective products can be extremely facilitated. In order to detect a mark consisting of such a peel-off portion 24 automatically, not visually, two electrodes 25, 26 are invariably brought into contact with the rear and front surfaces of the metal plate 1 for electrical detection.</p> |
