Fastener having primary and secondary threads

• Main Author: HSING; JOHN J
• Format: Patent
• Language: English
• Published: 04.04.2000
• Edition: 7
• Subjects: BLASTING; DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS ORMACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS,CLIPS, WEDGES, JOINTS OR JOINTING; ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVEFUNCTIONING OF MACHINES OR INSTALLATIONS; HEATING; LIGHTING; MECHANICAL ENGINEERING; THERMAL INSULATION IN GENERAL; WEAPONS

In a fastener having a head and a shank having a generally cylindrical portion with a proximal end adjoining the head and with a distal end, the shank has a primary thread formation and a secondary thread formation. The primary thread formation has a generally uniform radial dimension along the generally cylindrical portion. In one embodiment, the secondary thread formation has a radial dimension tapering outwardly so as to increase continuously from a region where the secondary thread formation originates near the distal end to a region where the secondary thread formation has a maximum radial dimension, which is equal approximately to the generally uniform radial dimension, the latter region being closer to the distal end than to the proximal end. If the secondary thread formation is interrupted, tapping torque is lower, as compared to tapping torque if the secondary thread formation is continuous. In another embodiment, the secondary thread formation has a radial dimension tapering outwardly so as to increase continuously from a region where the secondary thread formation originates near the distal end to a region where the secondary thread formation has a maximum radial dimension, which is less than the generally uniform radial dimension, the latter region being at the proximal end.