| 摘要 |
First, second and third bottom stepped portions 18, 20, 22 are formed stepwise at lead end portion of the casing 10 of a writing instrument. First, second, third and fourth lead stepped portions 32, 34, 36, 37 are formed stepwise at a bottom end portion of the lead portion (12) of the writing instrument. Lead end faces 24, 26 of the second and third bottom stepped portions 20, 22 are adhered with bottom end faces 40, 42 of the second and third lead stepped portions 34, 36 by means of ultrasonic adhesion. Prior to adhesion (Fig. 1A), the end faces 24, 26 include projections 28, 30. The joint ensures that the instrument will remain air tight if bent. <IMAGE> |
