A unique fastening design creates an almost weld-like joint, reducing problems related to vibration. In the Advanced Locking Fastener, a hardened fastener is slotted to capture metal shavings as a bolt bores into an unthreaded portion of a nut. The fastener system achieves a metal-to-metal thread fit with no play or open space between the fastener threads and the grooves of the nut, says Edwin D. Bowling, the engineer primarily responsible for the design at Ultra-Lok Fasteners, Busy, KY. The metal shavings collect and are contained in the slotted region on the lead end of the fastener. As the bolt bores into the nut, the metal cuttings compact and increase the locking effect.
In previous inventions, two holes for a passage directing metal cuttings into a bore that is being rethreaded. The collection and compaction of the cuttings in the Advanced Locking Fastener is achieved through use of a threaded shank terminating in a lead-in end and a headed end. The shank has a slot that is slightly deeper than the threads. One end of the slot includes a transverse bore.
The system has been used on large shaker screens that vibrate constantly to remove coal from mud and silt in an eastern Kentucky construction project. The assembly invention received a $7,500 economic development award from the Kentucky Science and Technology Corp.
A regular nut and bolt is typical industry thread to groove fit which is never a 100 percent fit, says Bowling. Over time and under movement, the typical bolt will back out of the nut and loosen. The Advanced Locking Fastener is described as a custom fit where metal bites and cuts a thread path. The result is a metal-to-metal fit. Further assisting in the tight fit is the containment and compacting of the metal cuttings in the slotted reservoir.
In another interested aspect described in the U.S. patent application, the new fastener can recut stripped or damaged threads on a previously threaded bolt. The invention has been awarded a provisional patent.