| 摘要 |
PURPOSE:To prevent a recessed part from being damaged and destructed by a method wherein grooves or projections are provided below the recessed part of a plastic molded item. CONSTITUTION:A plastic molded item 2 has a recessed part 1 on its outer surface. A plurality of holes or grooves 4 are provided on the surface below the recessed part 1. When the plastic molded item 2 is brought into contact with a plastic molded item to be welded and applied by ultrasonic wave through the horn 5 of an ultrasonic wave generator, the stress due to ultrasonic wave is scattered by the projections or grooves 4 provided on the surface below the recessed part 1, resulting in dispersing the stress from concentrating to the recessed part 1 and allowing to weld the contact part between both the molded items 2 and 3. Accordingly, no fear of damage at the recessed part 1 presents and, even if the recessed part 1 is damaged, no fear of destruction of the part presents. |
