Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Threaded fastener locked to a discreet structure – Member or portion thereof located between substructure and...
Reexamination Certificate
1999-12-20
2002-02-19
Saether, Flemming (Department: 3627)
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Threaded fastener locked to a discreet structure
Member or portion thereof located between substructure and...
C411S161000
Reexamination Certificate
active
06347915
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of locking devices for fasteners, and more particularly to a novel lock washer useful in combination with a fastener which prevents the fastener from being withdrawn from its tightened position and yet which will permit removal of the fastener upon disassembling of the fastener itself.
2. Brief Description of the Prior Art
In the past, it has been the conventional practice to prevent fasteners from backing off or from loosening from a tightened installation or assembly by the use of deformable elastometric materials or by use of spring or segmented washers which are disposed between the head of the fastener and a workpiece. Problems and difficulties have been encountered when employing such conventional devices which stem from the fact that many times the fastener can be loosened through vibration of the workpiece or by inadvertent impacts received from surrounding components in the fastened environment. In some instances, a variety of sharpened projections, such as wedges or deformable lugs, have been incorporated into washers which dig and gouge into the head of the fastener or into the workpiece itself in order to provide a tightened situation. In these instances, the workpiece is often gouged to the point where the integrity of the workpiece is adversely affected and material fatigue sets in which reduces the strength of the workpiece at the fastening assembly.
Prior attempts to provide devices which prevents or retards the backing off of fastener components are disclosed in U.S. Pat. Nos. 3,895,663 and 5,090,855. However, these disclosures require side or peripheral faces or surfaces that include flats so that hand tools such as wrenches can be used to effect engagement of the washers or components. The latter discloses and requires that the peripheral face include hexagonal wrenching flats
24
b
which are used for turning purposes. The peripheral surfaces or faces should be ineffective for turning purposes and should not be used to independently rotate the components with respect to each other.
Therefore, a long-standing need has existed to provide a nondeformable lock washer which will provide a positive locking action so that a fastener assembly cannot be loosened from its tightened position. However, such a lock washer should permit disassembling of the fastening device from the workpiece only when desired by the user or workman.
SUMMARY OF THE INVENTION
Accordingly, the above problems and difficulties are avoided by the present invention which provides a novel two-piece lock washer for use with a variety of fasteners wherein the lock washer itself includes a pair of components having opposite end opposing surfaces formed with a plurality of inclined ramps and locking faces so that when the components are pressed together, the ramps will ride upon each other until reaching a locking face where lock engagement is produced. The lock washer includes a central opening through which the shank of a fastener is passed and an exterior surface of the washer bears against the workpiece while the exterior surface of the other component bears against the head of the fastener. Thereby axial compression of the lock washer components causes the locking faces of the ramps to engage as the fastener is tightened against the workpiece.
Therefore, it is among the primary objects of the present invention to provide a novel lock washer which will maintain a fastener in a tightened position but is yieldable for removal of the fastener when it is desired to be removed by the workman.
Another object of the present invention is to provide a lock washer which gives positive locking action to an installed fastener and which can only be unlocked when the workman removes the fastener from the workpiece.
Yet another object of the present invention is to provide a novel lock washer for fasteners having a positive locking action which prevents and prohibits untightening of a fastener from its tightened position.
Still a further object of the present invention is to provide a two-component lock washer having interfacing inclined ramp surfaces and locking faces which permit a fastener to be tightened with a workpiece and thereafter prevents untightening of the fastener which might normally occur due to vibration of the workpiece or other impacting or jarring conditions.
REFERENCES:
patent: 3263727 (1966-08-01), Herpolsheimer
patent: 3895663 (1975-07-01), Bashline
patent: 4538313 (1985-09-01), Frieberg
patent: 4571452 (1986-02-01), Giubileo
patent: 5090855 (1992-02-01), Terry
patent: 5626449 (1997-05-01), MvKinlay
Marrs Roger A.
Saether Flemming
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