| 摘要 |
<p>An anti-cross threading fastener (10) having a threaded shaft portion with a major diameter and a minor diameter, may have a leading end shaft portion (26) devoid of screw threads and having a diameter less than the major diameter of the threaded shaft portion. The leading end shaft portion may also include a tip (27) having an at least partially substantially curved surface (28), and a groove (40) disposed about the shaft portion between the tip portion and the threaded shaft portion. A cylindrical shaft portion (70) may be disposed between the tip portion (27) and the groove (40). A portion (32) of the threaded shaft portion tapers narrowingly toward the tip portion, and the screw threads of the tapered threaded shaft portion have a flank angle greater than a flank angle of the screw threads of a non-tapered threaded shaft portion. The tapered screw threads may be formed of spaced apart lobes (37). Alternatively the fastener (110) includes a shaft portion having a first leading end portion (140) with a first end (132), a first threaded shaft portion having a first tapered threaded shaft portion (142) narrowing toward the first end, and screw threads of the first tapered threaded shaft portion have a flank angle greater than a flank angle of the screw threads of a first non-tapered threaded shaft portion (144). A cylindrical shaft portion (150) having a diameter less than a major diameter of the first threaded shaft portion may be disposed between the first end of the shaft portion (160) and the first threaded shaft portion (142). The first leading end portion may have a first tip portion with a partially substantially curved surface (180), or a driving tool engagement surface (162). <IMAGE></p> |
