APPLICATION TECHNOLOGY Real time bolt measurement
An experiment on a wind farm in Texas, USA, has demonstrated new applications for Norbar’s USM-3 ultrasonic bolt meter, which provides precise measurements for the elongation (resolution to 0.0001mm) and load in threaded fasteners from 25mm to over 15m long.
T
he experiment showed how Norbar’s USM-3 ultrasonic bolt meter can provide precise real time measurements of forces affecting a bolted joint, in this case a 2m long foundation bolt on a wind turbine tower.
The initial length of the bolt was recorded using the USM-3
meter and a magnetic transducer placed onto the bolt end. After a while, it could be noted that the elongation measurement seemed to be unstable and the value was constantly drifting. This was because, as the wind increased, it was pushing the tower in the direction of the foundation bolt, so that the joint was compressed slightly and the elongation decreased. The opposite occurred when the wind decreased. Norbar’s ultrasonic specialist Gregory Young explained: “This
ability to read minute fluctuations in the bolt tension, real time, can be of value to many companies dealing with bolted joint issues. Many sectors such as the automotive industry will also
be interested, since real time changes in bolt tension are highly important in automotive engineering.” Ultrasonic measurement performed by the USM-3 works
on a ‘time-of-flight’ principle, similar to sonar, with a small transducer placed on the head or stud end of the fastener sending an ultrasonic sound wave through the length of the bolt and back again, with easy to read data displayed on an LCD screen. The USM-3 incorporates digital signal processing and graphic displays of signal analysis and waveforms, which Norbar says makes it a truly user friendly instrument. Norbar Torque Tools is a specialist in the design, development
and production of torque tightening and measuring equipment. With its UK manufacturing base in Banbury, Oxfordshire, Norbar companies are located in Australia, China, India, New Zealand, Singapore and the USA.
Spirol boosts hydraulic pump assembly
When a manufacturer of hydraulic pumps required a method to permanently affix various sized bronze gears to 400 series stainless steel shafts, a solution was found using a heavy duty Spirol Coiled Spring Pin.
A
fter press fitting the gears into position, the hydraulic pump manufacturer drills a hole partially through the assembly, installs a heavy duty Spirol Coiled Spring Pin and stakes the entrance point for maximum security. Prior to Spirol’s involvement this was a manual three stage
process. Spirol has consolidated all the operations into one complete installation machine. As the manufacturer offered its customers many different gear/shaft assembly sizes, the machine needed to be versatile enough to accommodate the eleven existing assembly types and also had to be able to handle new variations as designed. Tooling changeover had to be quick and simple, with little to no machine adjustment. The cycle time had to be less than a minute and drill bits were expected to last at least 500 cycles. The Spirol Model DP machine consists of a standard Model
CR Pin Insertion machine, an automatic, production quality, high-precision drilling unit and a precision air-powered linear
slide unit to move the assemblies between the drill unit and installation/staking station. The machine features recirculating flood coolant in the drilling operation for temperature control and chip removal; an automatic clamping/part holding fixture unit; easily interchangeable tooling to accommodate eleven different assemblies; a common drilling and pin insertion elevation between all assemblies; pin presence sensing to verify a pin has been installed in the assembly; and a machine interface for programming and control of all functions. “Spirol’s solution provides a machine cycle time of 45 seconds,
drill bits yield 600 plus parts and tooling change-over takes less than 15 minutes between assemblies. This machine doubled the previous production output and provided a payback of less than 12 months. The solution has also increased the rate of assembly by 400%, eliminated screw walk-out, and improved the product’s appearance and function.”
Orlock in the automotive industry
Ornit Blind Rivet’s Orlock, a structural, breakstem fastener with a unique double-locking system and high shear and tensile strengths was originally designed for the automotive industry.
T
he Orlock was launched as a 6.4mm steel rivet and is still manufactured to this day to the exacting standard of ISO/TS 16949:2009 and ISO9001:2008. The Orlock family has since grown
into an extensive range of structural rivets including diameters from 4.8mm to 7.8mm, available in steel, stainless steel and aluminium. Different head types are also available including: protruding, countersunk, large and extra-large. The most recent addition to the Orlock range is the lightweight 7.8mm aluminium structural rivet. Ornit points out that the Orlock’s double locking
system ensures the mandrel remains tightly clamped within the rivet head, rendering the joint with high anti-vibration and water resistant properties, both qualities you want to have in a vehicle. Locking action is
142 Fastener + Fixing Magazine • Issue 74 March 2012
achieved by gripping grooves on the mandrel into which the rivet material is deformed. The deformation fills the space between the gripping section and the mandrel head creating a neat, tight locking action. This deformation spreads the clamp load over a large area, so it is ideal for soft, thin and brittle joint materials due to its homogeneous stress distribution. Ornit’s engineers designed Orlock for use in heavy
Hall: 21 Stand: H32
www.spirol.com
industry, automobiles, commercial vehicles and buses, freezer trucks, railway rolling stock, agricultural equipment, electrical engineering, and construction. “Orlock’s mechanical and physical characteristics make
it the preferred option for fastening solutions particularly in these applications.”
www.ornit.com
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