Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Having structure to restrict rotation of threaded – mating... – Comprising a thread lock
Reexamination Certificate
1999-10-25
2001-04-03
Wilson, Neill (Department: 3627)
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Having structure to restrict rotation of threaded, mating...
Comprising a thread lock
C411S263000, C411S324000, C411S432000
Reexamination Certificate
active
06210091
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a lock nut to be employed for fastening articles by tightening it on a bolt and is intended to hold the applied tightening force for a long time by devising the inside of the nut.
2. Description of the Related Art
In the prior art, the means for preventing the nut from becoming loose has been disclosed in Examined Published Japanese Patent Application No. 3-526, for example. Here a lower nut is used, in which a convex taper block is formed on the upper face thereof with an eccentricity relative to the axis of a thread, and an upper nut in which a recess concentric to the axis of the thread is formed to be fitted on the convex portion of the taper block. The nut is locked by a wedge effect at the taper portion by first tightening the lower nut on the bolt in an ordinary manner and then by tightening the upper nut.
This nut requires tightening twice because of the double type. When the tightening requires a torque wrench, the upper and lower nuts are simultaneously tightened so that the locking effect cannot be expected as a matter of fact. On the other hand, when the nut is to be removed, the thread portion may be broken when the loosening operation starts from the lower nut.
SUMMARY OF THE INVENTION
An object of the invention is to provide a lock nut which is simple to tighten while also maintaining a strong locking effect.
According to a first aspect of the invention, there is provided a lock nut for engaging with the thread of a bolt, comprising at least one thread block disposed in the body thereof that engages with the thread of the bolt and made eccentric with respect to the axis of the nut body.
According to another aspect of the invention, the eccentric thread block is contoured to have the same polygonal shape as that of a polygonal recess formed in the upper portion of the nut body and is confined in the polygonal recess.
According to still another aspect of the invention, a retaining portion is formed at the head portion of the nut body for retaining the eccentric thread block.
According to a further aspect of the invention, a clearance is formed between the retaining portion formed at the head portion of the nut body and the eccentric thread block for adjusting the gap between the thread crests of the nut body and the thread crests of the eccentric thread block.
According to a further aspect of the invention, a chamfer is formed at the bolt insertion end of the eccentric thread block.
According to a further aspect of the invention, a washer is arranged below the nut body.
According to a further aspect of the invention, a washer portion is formed integrally with the lower end portion of the nut body.
REFERENCES:
patent: 1275182 (1918-08-01), Ross
patent: 1667751 (1928-05-01), Tarwater
patent: 2318398 (1943-05-01), Hungerford
patent: 2815788 (1957-12-01), Tarwater
patent: 5752793 (1998-05-01), Wu
patent: 708905 (1931-05-01), None
patent: 3-526 (1991-01-01), None
Matsuda Keiji
Ono Rikio
Takata Shigenobu
Kawasaki Steel Corporation
Oliff & Berridg,e PLC
Wilson Neill
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