| 摘要 |
1365813 Self tapping and captivating screws ILLINOIS TOOL WORKS Inc 20 Jan 1972 [21 Jan 1971] 2790/72 Heading B3N A self-captivating screw has a head 12, a threaded shank portion 16, this portion including means 18 for forming mating threads in a pilot hole, and a work-entering portion 24 including screw captivating means 30 having a maximum diameter greater than the root diameter of the threaded shank portions, less than the crest diameter of the threaded shank portion but greater than the inner diameter of the pilot hole. In operation the screw is forced through a hole in a workpiece and rotated to form a thread therein. The inner diameter of the hole after thread forming therein is less than the maximum diameter of the captivating means. This means may have 3, 4 or 6 holes. |
