| 摘要 |
<p>A blind rivet, for anchoring in relatively soft material such as softwood, comprises a tubular shell (14) with a weakened portion (19) at the end remote from the head (18), and a stem (15) with an enlarged head (29) having a smooth underhead curve (32). The weakened portion (19) of the shell has four longitudinal V-section grooves (24) on its inner wall. In addition, the weakened portion (19) has a wall thickness which is less than that of the remainder (22) of the shell, the junction between the two parts presenting an internal annular shoulder (23). When tension is applied to the pulling portion (26) of the stem, the stem head (29) enters the weakened portion (19) and splits it apart along the grooves (24) to form legs which anchor in the soft material. The higher strength of the remainder part (22) of the shell prevents the stem head passing beyond the shoulder (23) before the stem fractures at the breakneck (27).</p> |
