Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Headed fastener element with nut – washer – securing means or cap – Headed bolt or screw with threads and complementary nut
Patent
1995-07-11
1997-06-10
Saether, Flemming
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Headed fastener element with nut, washer, securing means or cap
Headed bolt or screw with threads and complementary nut
411527, 411437, 411414, F16B 3702, F16B 3302
Patent
active
056369565
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to fasteners, and particularly to fasteners of the type comprising screw means.
Sheet metal threadform fasteners are well known and used in industry for low torque fastening. Fasteners of this type sometimes comprise a generally "U" shaped clip having adjacent limbs, one of which limbs has a threadform aperture arranged to matingly engage with a threaded shaft of screw means comprising a bolt or screw, the other limb having a plain orifice through which the shaft may pass.
We have now devised an improved fastener suitable for use in applications requiring higher torque than is achievable with prior art fasteners of the type referred to.
According to the invention, there is provided a fastener comprising, in combination: threaded shaft have an asymmetrical surface profile in the axial direction of the shaft; and therethrough, said aperture being preformed to have an at least partly helical threadform-defining edge which is shaped and dimensioned such that the threaded shaft of said screw means may be threadably mated therewith.
In addition to the inventive combination of a fastener comprising screw means and a fastening strip or sheet as defined, it is also believed that screw means as defined herein is novel per se.
It is preferred that radially the outermost portions of the crests of the screw thread of the screw means are substantially flat.
Typically, the crest of the screw thread is defined by respective flank portions, the flank portions preferably comprising respective substantially flat portions.
It is preferred that the flank portions are orientated at respectively different angles to the axis of the threaded shaft. Advantageously one of the respective flank portions is orientated substantially perpendicular to the axis of the threaded shaft with the other one of the respective flat portions being inclined at an acute angle, preferably in the range 50.degree. to 70.degree., to the axis. Desirably, the respective flank portions of the crest of the head are connected by a crest portion extending transversely to the respective flank portions.
It is preferred that the flat flank portion orientated substantially perpendicular to the axis of the threaded shaft is less extensive radially than is the flat portion orientated at an acute angle to the axis of the shaft.
It is preferred that the threaded shaft is provided with a drivable end or head portion, such as a bolt or screw head or the like, to which a torque may be applied.
Typically, in use the threaded shaft will be driven through at least one apertured object body (such as one or more plate members) and secured in place by the fastening strip or sheet such that the or each object body is securely gripped between the drivable end or head of the threaded shaft and the fastening strip.
It is particularly preferred that the volume of material comprising the thread between the minor and major diameters of the threaded shaft is not less than, and more preferably greater than, the volume of the space between adjacent thread portions between the minor and major diameters of the threaded shaft.
Typically one, or more preferably both, of the screw means and the fastening strip or sheet are of metallic construction.
Advantageously, the fastening strip or sheet comprises a generally "U" shaped clip having first and second limbs extending adjacent one another and away from an interconnecting web portion. Typically, the raised portion of the fastening strip provided with the threaded aperture is provided on one of the limbs.
Typically, the threadform-defining edge of the aperture in the raised portion of the fastening strip will be substantially helical at least along a portion thereof. Advantageously, the helical portion of the threadform-defining edge comprises substantially one complete helical turn. Typically corresponding portions of the threadform-defining edge, one helical turn apart will be spaced in the axial direction by a distance substantially equal to the pitch of the thread of the threaded shaft.
Desirably, the raised
REFERENCES:
patent: 1411184 (1922-03-01), Rosenberg
patent: 2169057 (1939-08-01), Place
patent: 2171773 (1939-09-01), Von Mertens
patent: 2172258 (1939-09-01), Place
patent: 3124191 (1964-03-01), Forslund
Davies Philip A.
Emmett John E.
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