Air springs battle friction, grit in conveyors

A simple way to avoid this problem is to employ spring actuators known as Airstrokes, says Simon Agar, the general manager of Air Springs Supply Pty Ltd.
Airstrokes are identical in construction and durability to the Firestone airbags used every day in the suspensions of heavy trucks and semis, including big earthmoving vehicles.
The highly engineered rubber and fabric Airstrokes are flexible-wall, bellows-type air cylinders that are suited to the engineering of assemblies for high repetition tasks, for which they are inflated and deflated rapidly. 
?An Airstroke?s column of air is in a fabric-reinforced rubber envelope,? explains Simon Agar. ?The ends are sealed by bead plates which contain the attachment hardware for the part, normally a blind tapped hole called a blind nut. An air fitting, in one bead plate, allows fluid (air) to be introduced into the chamber. The fabric in the side wall of the bellows restricts radial expansion, so pressure is built up, causing axial extension. 
?Each style is a heavy-duty balloon. Air springs are available in a variety of styles, sporting differing components that control the shape and path of axial extension, but their basic design is the same.?
To select the right air spring, you need to know the force necessary, the required stroke and environmental concerns. A variety of air springs are available. Airstroke actuators provide 40,000kg of pushing or lifting power. With power strokes of up to 350mm, they are powered by simple, basic compressor equipment found in nearly every factory.
Airstrokes are particularly suitable for belt scrapers, an unglamorous but essential component of conveyor systems. Their blades or brushes bear against the moving conveyor belt to remove material sticking to it.
?In addition to ensuring that scrapers are made from the correct material, it is important to pay special attention to the style of actuation,? says Simon Agar. 
While in some instances, metal springs, flexible blocks or torsion bars will satisfactorily position the scraper adjacent to the belt surface, other applications require more sophisticated, flexible and supple arrangements. Flexible pneumatic actuators, such as Airstrokes, can provide these.
As the amount of force they exert against a surface varies in continuous proportion to the amount of air pressure contained within them, air springs can adjust to different load requirements simply by varying this pressure. In addition, they provide force evenly over the surface upon which they are acting and will undulate over irregular loads passing beneath them, flexing with the load profile if necessary.
In addition to making air springs easy to install in compact spaces, this ability to bend with load (and to tolerate high side loadings) means the air springs will perform where more rigid alternatives would break or wear.
The air springs? other advantages have been proven over a wide range of materials handling uses, extending from conveyor direction gate actuation, lift sections and bumper stops through to ram cylinders, die cushions, counterbalances, clamps, lifters, valve operators, flexible connectors, shock absorbers and isolators.
The capital cost of an air spring is less than half that of a pneumatic cylinder with equivalent capabilities. Sizes are available from fewer than 80mm to over 1000mm in diameter. The larger sizes allow force up to 40,000kg each, using only 7 bar (100psi) air pressure.
They are also compact and easy to install because of the way the flexible-wall air spring operates: it is compressed to its minimum height then extends when pressure is applied. In most cases, the minimum height is less than the available stroke. As a result, air springs can be put in a very compact space and extended to more than twice their starting height, a tremendous benefit in floor-mounted lifting devices and conveyors.
Source: Air Springs Supply Pty Ltd

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