GB2051996A - Single thread nut with free spinning washer - Google Patents

Abstract

A fastener comprising a coupled, mutually rotatable nut and washer assembly. The nut 11 has an inverted cup shape and side walls. The inner surfaces 23 of selected side walls have inwardly projecting shoulders 24 formed therein. The washer 12 has an upwardly extending portion 18 defining an outwardly flared upper rim 20. The fastener is formed by inserting the upwardly extending portion 18 through the open end of the nut and snapping the flared rim 20 past the shoulders 24. The rim and shoulders cooperate to couple the washer and nut together and to permit their relative rotation. No permanent deformation of either the nut or washer is required to effect the connection. <IMAGE>

Description

SPECIFICATION Single thread nut with free spinning washer The present invention relates generally to the field of fasteners, and more particularly to coupled, mutually rotatable, nut and washer assemblies.

Integral fastener assemblies which include nuts with attached or coupled washers are known in the prior art. In such fasteners the washers may be fixed to the nuts, so that the nuts- and washers do not rotate relative to each other. Alternatively, the nuts and washers may be coupled so as to be mutually rotatable with respect to each other.

The non-rotatable fasteners are the simplest to construct and the cheapest to manufacture.

However, when the fasteners are being tightened onto a stud or bolt, the washer can score the face of the workpiece against which it is being tightened. This may weaken the workpieces causing premature failure. Furthermore, if the surface is protected by paint or if it is plated, tightening the fastener can score the paint or plating layer, which may result in oxidation of the workpiece or in galvanic action between the fastener and the underlying surface.

Several configurations of relatively rotatable nut and washer assemblies are known, as exemplified in U.S. Patents 2,851,079 and 3,659,491, and British Patent 929,807. In such fasteners, the washers do not normally pivot with respect to the workpiece while the fastener is being tightened, which avoids scoring of the underlying workpiece.

The cited patents disclosed two general methods by which the washers and nuts are coupled to form a fastener. The first method is exemplified in U.S. Patent 3,659,491 and in British Patent 929,807, and includes providing a central barrel, the interior surface of which is threaded to accommodate a threaded bolt or stud. The washer is attached to the lower end of the barrel. A second method, exemplified in U.S. Patent 2,851,079, eliminates the central barrel, and the washer is held by deforming in outer sidewall of the nut. In the devices disclosed in all three patents, however, the respective nuts are deformed after the washer has been slipped onto them. In U.S. Patent 3,659,491 and in British Patent 929,807, the ends of the barrels are slipped through the apertures in the washers and then flared to couple the washers to the nuts.In the fastener disclosed in U.S. Patent 2,851,079, an upwardly extending portion of the washer is first inserted into the nut, and the nut's sidewall is dented inwardly, the dent limiting the washer's axial motion and thereby coupling the washer to the nut.

These methods of assembly are difficult to perform, as it is necessary to assemble the washer onto the nut, hold it in position, and simultaneously deform the nut to effect the coupling.

It is therefore an object of the invention to provide a new and improved fastener. It is another object of the invention to provide a fastener comprising a nut rotatably coupled to a washer and formed in a new and improved manner.

In brief, the invention includes a coupled, mutually rotatable nut and washer assembly. The nut may be cupshaped and include several preformed, inwardly extending shoulders projecting from the inner surface of the sidewalls. The washer may include a radially extending skirt portion and an upwardly extending portion including an outwardly flared rim. The fastener is formed by inserting the washer rim through the nut's open end and snapping it past the shoulders.

The shoulders cooperate with the rim to rotatably couple the washer to the nut.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings, in which: Fig. 1 is a top plan view of a fastener according to the invention, Fig. 2 is a side elevational view of the fastener depicted in Fig. 1: Fig. r is a sectional view taken along lines 3-3 in Fig. 1; Fig. 4 is a top plan view of a washer useful in a fastener according to the invention; Fig. 5 is a sectional view of the washer shown in Fig. 4 taken along lines 5-5; Fig. 6 is a view of the fastener assembly in Figs.

1 through 3 as applied to a cooperating stud Figs. 1 and 2 illustrate a fastener 10 embodying the invention, including a nut 11 and a washer 12.

The nut 11 and washer 1 2 are mutually rotatable with respect to each other.

Nut 11 is substantially shaped like an inverted cup, having six sidewalls 13 and a top 14. Top 14 defines an axial aperture 1 5. The edges 1 6 of top 14 that define aperture 1 5 are skewed so as to form a thread when fastener 10 is used on an unthreaded stud, as described hereinafter. Top 14 further defines notched 1 5a which cooperate with edges 16 to form the thread.

As exemplified in Figs. 4 and 5, washer 12 includes a peripheral, radially-extending skirt portion 1 7 having an axial upwardly-extending portion 1 8. The upwardly extending portion 18 tapers slightly inwardly to form a throat 1 9 and flares to form an upper rim 20. The throat 19 and rim 20 form a circumferential groove 21 in the outer surface of upwardly extending portion 1 8.

Skirt 1 7 may include downwardly-extending beveled portions 22.

Each sidewall 1 3 includes an interior surface 23. Selected interior surfaces 23 include an inwardly-projecting shoulder 24. The shoulders are all formed a preselected uniform distance from the open end of nut 11. Shoulders 24 may be formed by skiving material from the interior wall or may otherwise be moulded in using conventional techniques. Sufficient surfaces 23 are selected to include a shoulder 24 so that the washer, when assembled to the nut as described hereinafter, is coupled to the nut in a relatively rotatable assembly.

Nut 11 and washer 12 may be formed separately from sheet metal or carbon spring steel by any conventional method known in the art To assemble nut 11 and washer 12 to form the fastener 10, flared rim 20 of washer 1 2 is inserted into the open end of nut 11. Rim 20 is snapped past shoulders 24 to allow the shoulders to ride in groove 21. The shoulders ratain rim 20, preventing the rim from slipping out of the open end of nut 11 thereby preventing the nut and washer from separating.

Fig. 6 shows the fastener 10 in use on a stud 25. The stud need not be previously threaded, as the notches 15a and edges 1 6 cooperate as the fastener is being turned onto the stud 25 to form an appropriate thread in the stud. The nut is rotated onto the stud until the fastener is tight against work surface 26. After the washer contacts work surface 26, it stops rotating. Thus, washer 12 does not appreciably score the work surface 26 as the fastener is tightened. The beveled portions 22 of the washer 12 provide a spring-loaded support for nut 11 as it is tightened to ensure that the nut is straight on the stud.

It will thus be seen from the foregoing that the objects set forth above, among those made apparent in the preceding description, are efficiently attained. It may be seen that fastener 10 can be assembled without the necessity of holding the nut and washer in position with respect to each other while one or the other is deformed to effect the rotatable coupling. Since certain changes may be made in the above constructions without departing from the scope of the invention as defined by the appended claims, it is intended that all matter named in the above description and shown in the accompanying drawing be interpreted as illustrative and not in a limiting sense.

Claims (6)

1. A single-thread fastener assembly comprising a nut rotatably connected to a washer.

said nut having a generally inverted cup shape.

including a pluraiity of side walls each having an inner surface, and a top member, the top member including means defining an aperture, the periphery of the aperture being skewed to define a thread, the lower end of the nut being open, the inner surfaces of at least some of the side walls each having a shoulder formed in the respective surface projecting radially inwardly, said washer having a radially extending skirt portion and a portion extending generally upwardly and defining an upper rim radially flared near the top thereof, the assembly being formed by inserting said upwardly-extending portion of said washer into said open lower end of said nut, and snapping said flared rim beyond said inwardly projecting shoulders, said rim being retained by said shoulders to rotatably connect said washer to said nut.

2. A fastener assembly as defined in claim 1 wherein said upwardly extending portion of said washer includes a radially tapering portion immedialy below said rim to form a circumferential guide, said shoulders riding in said guida.

3. A fastener assembly as defined in claim 1 or claim 2 wherein said shoulders are formed by skiving the respective inner surfaces of said nut.

4. A fastener assembly as defined in any preceding claim, wherein said skirt portion extends downwardly and radially outwardly.

5. A fastener assembly as defined in any preceding claim wherein said skirt portion includes a downwardly extending beveled portion.

6. A single-threaded fastener assembly substantially as described herein with reference to the accompanying drawings.