| 摘要 |
<p>A screw having an elongated threaded shank includes a head integrally formed on the upper end of the shank. Corner portions of the head are weakened to a predetermined strength correlated with a predetermined torque to which the screw may be tightened into a workpiece by a tool engaging the weakened corner portions. As the screw is threaded into the workpiece by the tool, the weakened corner portions are folded along sides of the head when the tightening torque applied to the screw exceeds the predetermined torque. The folded corner portions thus provide visual evidence that the screw is tightened properly in the workpiece.</p> |
