Microdot Inc.

Arthur J McKewan

Gerald P Downey

An internal thread configuration for use in nuts and threaded holes has a wedge ramp root section that is convexly curved so that a portion thereof is substantially parallel to the axis of the threads.

Convex wedge ramp thread configuration

In a fastener assembly of the type in which both the internal and external threads have wedge ramp root and crest sections, one of the thread forms is asymmetric so that its following flank has a different flank angle than its leading flank and different from the corresponding following flank of the other thread.

Threaded fastener assembly

A one-piece sheet metal insert for use in anchorage and fastening applications. The insert is designed to provide sufficient resistance to axial pull-out loading when utilized in relatively soft material workpieces such as structural foam plastic. The insert is also configured to take the clamp load between its collar and internal thread ribs thereby preventing tensile and compressive forces from being applied to the workpiece material surrounding the insert which commonly cause creep to occur.

Sheet metal insert for foam plastic

A threaded fastener, such as a bolt, has an externally threaded shank with a standard thread portion along its end portion and a modified thread portion adjacent to it, the modified thread portion having a substantially inclined root section enlarged to interfere with and swage the crest of an internal thread in contact with it and having the leading flank adjacent the inclined root backset to provide space for the swaged crest.

Prevailing torque bolt

A threaded fastener particularly suited for use with plastics having spaced apart threads and a negative rake or 'hook' formed at the crest of certain of the threads so that axial force applied by the fastener in the direction of the head is translated in part towards the axis of the fastener, thus increasing the failure load of the screw assembly and eliminating premature stripping of the screw threads. Also disclosed is the preferred manner of making the threaded fastener of the present invention.

Self-tapping screw for use in plastics

A self drilling, closed end, blind rivet has a hexagonally shaped flange, or other suitably shaped means of driving, at one end and a hardened drill bit at the other end, with the two being joined by an integral sleeve wall with a rolled groove in it that forms an internal chamber to retain the head of a mandrel. Withdrawal load on the mandrel, after the rivet has been inserted through a hole drilled by it in a plurality of layers to be joined, will upset the sleeve wall into a folded flange that coacts with the hex head, or other driving means, to tightly grip the outside face and the blind face of the layers being joined.

Self drilling blind rivet

A threaded fastener assembly comprises a bolt with standard 30.degree. flank V-threads and a nut with 30.degree. flank V-threads modified to have wedge ramps between adjacent top and bottom flanks and characterized by the uniform pitch of the nut threads being a predetermined amount less than the uniform pitch of the bolt threads so that there is flank to flank contact between the engaging nut and bolt threads a the top of the nut and the bottom of the nut.

Prevailing torque nut

The shank of a self tapping screw has a thread forming section, a threaded section, and a reduced diameter section interconnecting the forming and threaded sections. The thread forming section forms internal threads into a known thread form that has a wedge ramp at its root. The threaded section comprises threads of standard form having the same pitch as the thread forming section. The reduced diameter section is slightly longer than an integer multiple of the pitch so that the threaded section is backset slightly from the forming section.

Growing community of inventors

Rochester, MI, United States of America

Arthur J McKewan