Cylinder Pillow

elastic properties of polyurethane, the mechanical strength and wear resistance make it a good material for pneumatic seals. When the polymer composition and design development are sensitive to the specific demands of pneumatic, polyurethane joint modern tire change of the operating limits to new levels. This has been validated by rigorous testing and validation.

pneumatic actuators are key materials handling and automation systems for transportation, clamping and positioning of goods, boxes, shutters, doors, etc. A typical pneumatic cylinder (Figure 1) contains many static and dynamic seals . The dynamic seals are:

double-acting piston seal (often two joints U-cup)
rod seal and wiper of land (often combined into a single element)
Two joints of padding for the end adjustable pneumatic damping.

The dynamic seals have much to work with:
Oil-free compressed air using only the minimum lubrication has been applied when assembling cylinder
Operating pressures to 100 psi with excursions to 360 psi for cushioning
creep rate of 3 + ft / sec.
A temperature range of -4 ° F to +176 ° F
With a typical lifetime cumulative travel at least 4,000 miles, the area must maintain dynamic contact lubricating grease. A flexible lip seal geometry provides a low radial force, and a rounded contact area allows the lip to float on a film of grease.

If the hydraulic seals are used in pneumatic cylinders, the edges of the high radial force and strong sealing would scrape the fat out of the contact area. Fat is collected at the end and the ensuing poor lubrication would result in high friction, high wear and shorten the useful life.

Seal elegant design
Joint design is consistent with the principles described above. Other features ensure the smooth operation in all operating conditions.

Piston seal: seals U-cup-type have been used in pneumatic cylinders for many years. The design of Figure 2 shows several peculiarities. He has a tenuous link between the sealing lips and body to achieve low radial force. Go to the contact area is larger the lip to give stability under pressure.

Notched two lips and the outside diameter of the rear prevent malfunctions. The notches on the side of the outer sealing lip ensure appropriate activation when the pressure increases. Notches on the outer diameter of the back and the Act on the lips as channels internal decompression of the pressure case is trapped between the two half-cups in a double-acting piston. Without these slots, a trap pressure and friction, can tip the seal into the groove, causing a cylinder unusable. The rounded contact surface of the lip seal has been optimized by finite element analysis to ensure proper operation of the pressure range of the whole.

A polyurethane material has been developed for the specific requirements of pneumatic applications. The 83 Shore A hardness is relatively low to minimize the radial force. With all its good compression, low friction and exceptional wear resistance, it provides the conditions necessary for good functional properties and long life.

Rod Seal: The rod seal is designed to meet grooves for pneumatic cylinders to ISO 15552. The seal has a sealing lip and a lip wiper to ground, and is secured by a restraint "nose" in outer diameter. The seal may be mounted in a gland unfragmented by pushing it into the hole until the nose retainer snaps into the groove of the coupling of the housing bore. The outer static sealing lip is chamfered for easy installation.

As the seal is fixed only by his nose retainer, the gasket material must be rigid enough to withstand the axial forces of pressure and friction. Therefore, a harder material (94 Shore A) is used to maintain proper sealing orientation.

Gaskets and Cushioning ensure the smooth movement of the piston to the position hopeless. The seal pad (F.