Bearing stress-free locking device

Abstract

A locking device is provided for preventing adjacent threaded fasteners from rotating while not bearing any of the preload stress of the fasteners. The locking device includes: a plurality of locking rings, each locking ring being of sufficient diameter to surround the sides of one of the adjacent fastener heads and wherein each locking ring is made from a pliable material such that the locking ring may be deformed to closely fit its associated fastener head; and a torque member, connected to each locking ring, for providing torque to prevent each locking ring and its associated bolt head from rotating.

Description

BACKGROUND OF THE INVENTION1. Field of the InventionThe present invention relates to locking devices which are used to provide torque to prevent a threaded fastener (bolt and nut, cap screw, or the like) from rotating and, more particularly, to a locking device which, in addition to providing torque, does not bear any preload stress from the fastener head.2. Prior ArtIn many applications, bolts and nuts or cap screws are used to join components. A significant number of these applications require that these threaded fasteners be tightened to a very high torque. This torque creates a large amount of preload stress between the fastener head (or nut) and the component. Even with these highly torqued fasteners, a common problem is that, under certain conditions, particularly when the components vibrate, the fasteners tend to work loose. This problem has been addressed in the prior art by the use of several devices which are designed to prevent an individual bolt or nut from rotating, inc...

AI Technical Summary

Benefits of technology

In further accordance with an alternate embodiment of the present invention, fasteners with special fastener heads are provided to be used in conjunction with the disclosed locking device. In particular, the fastener heads include indentations around the sides of the heads and, after the fasteners have been tightened, the locking rings of the fastener device are crimped such that they protrude into the indentations. Advantageously, the indentations are formed longitudinally with respect to the fastener head and are taller than the locking rings. With this feature, when the locking rings are crimped so as to protrude into the indentations, the top of the indentations prevents the locking rings from sliding off of the fastener head.

Problems solved by technology

This torque creates a large amount of preload stress between the fastener head (or nut) and the component.

Even with these highly torqued fasteners, a common problem is that, under certain conditions, particularly when the components vibrate, the fasteners tend to work loose.

Each of these devices has its own drawbacks, however.

Additionally, lock washers provide only a limited amount of torque to prevent rotation of the bolt.

Lock nuts, while typically not bearing any preload stress, also provide a limited amount of torque to the bolt.

Castle nuts with cotter pins, like several other types of locking devices, require a particular orientation of the bolt (or nut) and, therefore, do not allow the bolt to be tightened as desired.

First, the tabs b often are not aligned properly with the bolt head when the bolt head is tightened to the desired torque and, therefore, the tabs b provide reduced holding power.

While these stresses are not too large for a hardened bolt, they are too large for the locking plate L which must be made from a softer material in order to allow the tabs to be bent around the bolt head.

Moreover, hardened material cannot be used for the lock plate because, while extreme force might be applied to bend tabs made from hardened material, such force could cause the hardened material to crack.

Additionally, while providing additional material under the bolt head would increase the load capacity of the soft lockplate, this solution is difficult to implement because the diameter of the holes in the lockplate must include sufficient tolerance to allow for variations in fastener diameter as well as variations in the distance between fasteners.

Further, the use of larger fastener heads is also not a suitable solution because many applications require a particular size fastener head, either because of space, material, or financial constraints.

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