Screw nail

摘要

In the case of a screw nail for fastening heat-insulating panels or the like on a sheet-metal substructure, the drive-in end is formed with a coarse thread which is overlaid with annular grooves with sharp-edged outer groove webs. The steel shank is coated with a plastic sheathing which is adjoined at the top by a disc-like plastic head. The external diameter of the drive-end is greater than the diameter of a smooth shank portion provided between drive-in end and the plastic sheathing. The screw nail is double secured in a sheet-metal substructure by means of such a configuration of the drive-in end. The coarse-threaded end overlaid with grooves engages particularly strongly on the hole borders formed. The step between the threaded end and the smooth shank portion prevents, once the nail has been driven through by this drive-in end, the nail from being drawn out from its substructure unintentionally.