| 摘要 |
A fastener unit for clamping plastic material having a first predetermined thickness to a relatively thin sheet metal support having a second predetermined thickness. The fastener unit includes a spacer collar having a length substantially equal to the first predetermined thickness, the plastic having a hole to receive the collar. The collar surrounds the upper portion of a threaded shank and the end abuts the sheet metal. The spacer collar has an internal diameter which forms a gap with the threads of a size approximately equal to the second predetermined thickness. As the fastener is threadingly advanced into the sheet metal, the end of the collar serves as a fulcrum about which the threads bend the material which forms the edge of the hole into the gap increasing the stripping torque of the fastener unit. |
