fastening Archives - Windpower Engineering & Development

Tough tubing tasks made much easier

Windpower Engineering — Thu, 06 Oct 2011 15:56:03 +0000

The light, portable TurnPro tool can automatically assemble two ferrules and a high-purity-tube fitting to manufacturer recommendations. The tool is easy to handle because controls in the power house (motor body) accurately measure 1.25 turns from “finger tight” and then shut the motor off. The tool provides a repeatable fitting make-up every time. The tool handles 1/16 to ½ in. heavy-wall tube and tees, crosses, and valves. It also provides data logging for quality control and reduces labor costs by making workers more efficient. Also important, it simplifies overhead installations because workers need only one hand.

The ferrule-tightening adaptor can be swapped for ProCut, a device which makes clean tube cuts even in heavy wall stainless steel fast and efficient. A ProBend head for the same motor body lets operators set needed bend angles for automatic bending, or use a touch button to set bends to any needed position by observation.

SSP
www.mysspusa.com

WPE

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Pinned joints assemble tubular transmission poles faster

Windpower Engineering — Thu, 06 Oct 2011 15:05:01 +0000

The arms on tubular steel transmission poles typically attach using as many as 16 bolts. It takes a small crew about a half an hour to get an arm in place, attach all of those bolts and nuts, and then tighten to specifications. Engineers at Thomas & Betts developed a connection using a pinned joint that requires a fraction of the time and fewer people to install. The “QuickPin” arm connection uses long pins instead of bolts, though made of the same material as bolts. The tapered pins can be hammered into position to force quick alignment. A flat on the pin heads lets a worker turn them so locking holes in the point end line up with the other pins. A locking rod then goes through the pins to secure them in the joint. Available only on Meyer poles, the QuickPin costs about the same as traditional arm connections but has significant time and crew savings.

Thomas & Betts
Meyer Steel Structures
www.meyersteelstructures.com

WPE

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Tower bolting technology improved with interlocking cam fasteners

Windpower Engineering — Fri, 08 Apr 2011 13:08:27 +0000

Greg White
Vice President
DISC-LOCK International
Culver City, Calif.
www.disc-lock.com

Wind-turbine towers appear to be rising to new heights–literally. As blade lengths increase to capture more wind energy, towers must also reach higher to accommodate the longer blades.

Increased tower dimensions also translate into elevated levels of vibration and stress on tower fasteners, which can lead to loosening and bolted-joint failure. However, fastener failure can be eliminated with a locking washer.

Locking washers come in pairs with cam faces glued together.

The working principle behind the device is simple: It consists of two washer-shaped pieces that are preassembled (glued pairs), and have inclined cams on one side with a series of radial ridges on the other. On installation, the two cam sides are mated together and placed between the nut and joint material. Under vibration, the nut attempts to rotate loose. But because the cam angle is greater than the bolt-thread-pitch angle, the interlocking cams and non-slip ridges of the washer work together. The resulting jamming effect prevents loosening and further locks the assembly, thereby maintaining joint integrity. The result: a vibration proof fastening system.

Locking washers from DISC-LOCK have a steeper cam angle than the angle on bolt threads. Hence, vibration cannot turn them loose.

The locking washers also offer a fastening system that combines a heavy hex nut and tension-control bolt. Tension-control bolts are replacing conventional high-strength, friction-grip bolts and swaged-collar rivets because they are quick and easy to install with a lightweight electric shear wrench. Guaranteed tension and a visual inspection eliminates the likelihood of operator error and ensures engineers that connections are tightened in accordance with specifications. This bolting system is easily removed and can be reused. Other types of secure bolts are not reusable because they must be burned or cut off for removal, thus destroying the bolt.

The bolt spline works with the electric shear wrench.

The electrically powered shear wrench is lighter than hydraulic wrenches, a distinct advantage when considering tower height and precarious installations. This translates to a one-man operation that trims installation cost. The DISC-LOCK shear wrench uses an outer socket to engage the nut, while an inner socket engages the bolt. The two sockets rotate in opposite directions allowing the nut to turn while the bolt remains stationary. This counter-force operation transfers no torque to the operator, thereby reducing fatigue that can cause carpal tunnel syndrome.

Other interlocking cam fasteners from the company can help maintain bolted-joint integrity on wind farms. These include hex-head bolts for use in blind-hole applications and locking nuts that can be installed with standard tools. Forces that induce other lock nuts to loosen cause locking cam nuts to tighten.

Two sockets on the electric shear wrench work in opposite directions, turning the nut to turn while holding the bolt stationary. Zero torque to the crew member means less stress and fatigue on him.

WPE

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