Vsi Corporation

Roland A Wheeler

Jack Rath

Peter M Downie

Wrenching lobes of an internally threaded nut are separated by circumferential, tapered walls so that the lobes and contiguous portions of the walls deform in radial compression upon reaching a predetermined preload and displace radially inwardly while the central portions of the walls deform radially outwardly, but do not interfere with the tool that sets the nut.

Self-locking fastener, fastener system, and process

An aerospace fastener comprises a blot with a roll-formed thread, and a nut with a similar thread having a uniform pitch P. The bolt has a cylindrical shank, a threaded tip and a run-out zone between the shank and tip. The thread root in the run-out follows a smooth S-shaped curve with the concave portion preferably having a radius in the range of from 2P to 2.7P. The run-out extends from 1.4P to 2.3P from the maximum grip plane of the bolt, and preferably extends from 1.6P to 2P from the maximum grip plane. The root of the thread in the run-out lies within an envelope defined by boundaries which take into account the maximum and minimum material conditions of the bolt. The nut has a run-in truncating the crest of the nut thread complementary to the run-out to clear the root of the bolt thread when the nut is assembled on the bolt in the minimum grip condition. This permits the nut to be assembled on the bolt further than in a conventional combination, and shortening of the nut and bolt by at least 1P to save weight.

Lightweight fastener

An aerospace fastener comprises a bolt with a roll-formed thread, and a nut with a similar thread having a uniform pitch P. The bolt has a cylindrical shank, a threaded tip and a run-out zone between the shank and tip. The thread root in the run-out follows a concave curve having a radius in the range of from 2.0P to 2.7P and extends 1.58P to 1.8P from the maximum grip plane of the bolt. The nut has a convexly curved run-in truncating the crest of the nut thread complementary to the run-out to clear the root of the bolt thread when the nut is assembled on the bolt in the minimum grip condition. This permits the nut to be assembled on the bolt further than in a conventional combination, and shortening of the nut and bolt by at least 1P to save weight.

An aerospace fastener comprises a bolt with a roll formed thread, and a nut with a similar thread having a uniform pitch P. The bolt has a cylindrical shank, a threaded tip and a run-out zone between the shank and tip. In the run-out, which is no longer than 2P, and in preferred embodiments is in the range of from 1.6P to 1.9P, the root of the roll formed bolt thread increases diameter continuously from the minor diameter of the tip thread to the diameter of the shank. The nut has a conical run-in truncating the crest of the nut thread parallel to the run-out to clear the root of the bolt thread when the nut is assembled on the bolt in the minimum grip condition. This permits the nut to be assembled on the bolt further than in a conventional combination, and shortening of the nut and bolt to save weight. Preferably the crest of the bolt thread is at the major diameter of the tip thread at distances beyond 0.75P from the maximum grip plane of the bolt.

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Los Angeles, CA, United States of America

Roland A Wheeler