Designers Corner
November 20, 2000
Nuts about quick insertion
Push it in, but don't expect to shake it out. That's the point of a new fastener that brings together a quick-insertion nut and vibration-resistant threads.
Combining a quick-insertion nut with vibration resistant thread form, this fastener shoots for an easy installation that won't work its way loose. |
The fastener employs an expandable nut whose three pieces, or "shells," are wrapped by a circular spring or o-ring. A simple push of the screw forces the shells to move apart radially and make way for the threads. Only after the screw has been pushed past the spring-retaining groove at the bottom of the nut shells does a conventional tightening process begin. To keep the nut from twisting as the pre-load is applied to the screw, the fastener relies on a locking washer. It completely encloses the nut and has three key pins that mate with seats in the nut when the screw has extended beyond the spring.
To impart some vibration resistance, the nut also sports patented threads with flat tops and an included angle that differs from the bolt's thread angle. The crest of the nut bites into the root area of the bolt thread in an elastic deformation process. And this wedge-like contact targets the effects of loose tolerance fit between mating threads-a major source of vibration loosening.
Roopnarine, Honeybee Robotics, 204 Elizabeth St., NY, NY 10012; Tel: (212) 966-0661; Fax: (212) 925-0835; E-mail: [email protected] .
Equal in any attitude
SteelPaw(TM)Compact Rope Isolator provides simultaneous shock and vibration capabilities.
Smaller than traditional wire-rope isolators, SteelPaw provides simultaneous shock and vibration attenuation where sway and package space is a premium. |
Wire attachment points at the four corners provide equal damping in any attitude. The all-metal design operates consistently from -150F to 500F.
Requiring no maintenance, SteelPaw is said to be suitable for hostile environments because it's unaffected by chemicals, oils, ozone, and abrasives. Available in load capacities ranging from 0.1 to 74 lb, the compact wire rope isolator is targeted at applications such as disk drives, medical equipment, mobile electronics, small pumps, motors, and avionics equipment.
Norm Macenzie, Enidine Inc., 7 Center Dr., Orchard Park, NY 14127; Tel: (716) 662-1900; E-mail: [email protected] .
Screw snaps in place
The Snap-In Panel Fastener, a hand-installed alternative to loose thumbscrews, installs with a snap and a few twists.
The Snap-In Panel Fastener installs by hand and eliminates the need for loose fasteners. |
The snap occurs as the fastener pushes into a hole in the mounting panel, causing a barbed thermoplastic retainer to engage an undercut in the panel's opposite side. The retainer completely encircles the screw and attaches it to the mounting panel. Next comes the twisting as the screw joins the mounting panel to its mate.
The attachment between screw and panel isn't permanent; the entire fastener assembly can be snapped out of its mounting hole for reuse.
The snap-in fastener will soon be available in both metric and unified thread sizes and in a variety of screw-cap hues to permit color-coding.
Craig Link, PEM Fastening Systems, PennEngineering, Box 1000, Danboro, PA; Tel: (215) 766-8853; Fax: (215) 766-3631.
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