| 摘要 |
Structure for screwing on sheet metal an object having a fitting hole comprises sheet metal having a prepared hole formed therein in the shape of a saucer and also having a saucer-shaped lip which has a thickness equal to the thickness of the sheet metal and defines the prepared hole, and a screw composed of a screwhead, a shank depending from the screwhead, external threads formed around the shank and a substantially conical tip. The screw is passed through the fitting hole in the object and driven into the prepared hole in the sheet metal while catching the leading end of the saucer-shaped lip between the adjacent external threads. When the leading end of the saucer-shaped lip is clamped between the uppermost effective external thread and the adjacent effective external thread, the object is firmly clamped tightly between the screwhead and the sheet metal by synergistic effect of a force of the screw pulling up the saucer-shaped lip and a force of the saucer-shaped lip restoring to its original position against the pulling-up force of the screw due to its resilience. |
