One of the weakest links in high speed metal stamping and fabrication machinery can be the seals in traditional cylinders used to actuate the equipment involved.
This is especially critical in aggressive atmospheres laden with dust and waste, where such cylinders can clog up and wear prematurely over the millions of cycles for which they must operate.
One simple way to avoid this potential problem is to employ cylinders that totally lack such seals, says pneumatic actuation and isolation specialist Simon Agar.
Mr Agar, the General Manager of Air Springs Supply, has more than 20 years experience with Firestone air spring actuators known as Airstrokes.
These highly engineered rubber and fabric air bags are flexible-wall, bellows-type air cylinders which are ideally suited to engineering of assemblies for high-repetition tasks, for which they are inflated and deflated rapidly to achieve their purpose.
“Traditional cylinder designs contain a piston sliding within a housing of circular cross-section connected to the work by a rod passing through one end of the device. This design necessitates several guides and seals, which align and seal the sliding surfaces.
These allow a pressurised, contained column of fluid to apply force to the piston.
“An air spring uses none of these components to contain and channel its column of fluid.
An air spring contains its column of air in a fabric-reinforced rubber envelope, or bellows.
The ends are sealed by bead plates, which are crimped around the bead of the bellows.
These plates contain the attachment hardware for the part, normally a blind tapped hole called a blind nut.
An air fitting, generally 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, in essence, 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.”
In order to select the appropriate air spring, you need to know the force necessary, the required stroke and any special environmental concerns. A broad range of air springs is available to Australian industry. Airstroke actuators from Air Springs Supply give 40-40,000kg of pushing or lifting power. Offering power strokes of up to 350mm, Airstrokes are powered by simple, basic compressor equipment found in nearly every factory.
Australian industrial plants also use them as ram cylinders, die cushions, counterbalances, clamps, lifters, valve operators, flexible connectors, shock absorbers and isolators.
Mr Agar says Airstrokes have capabilities and limitations that set them apart from traditional metal-wall cylinders driven by the pumps and compressors in nearly every production plant.
Their performance has a critical bearing on the overall efficiency of pneumatic systems.
“We certainly don’t pretend they are the ideal actuator for all applications,” says Mr Agar, “ but we do contend that they are the ultimate actuator for many applications for which they are not always considered, including metal stamping and forming applications.
“And not only are air springs ideal actuators for many materials handling applications, but also they are a highly efficient isolator.
“An air spring not only lifts, but can also be used to isolate an object highly effectively, in which application they are known as Airmounts.”
Air Springs Supply Pty Ltd
Ph: 02 9807 4077
Australia's No.1 Manufacturing & Industrial Equipment Magazine & Directory