Accordion Bellows

Accordion bellows are convoluted, expandable, fabric or elastomer components used to protect screws, shafts, slide ways and other components from liquid, chips, dirt and other debris. These flexible, protective covers can withstand temperature extremes and are resistant to oils, chemicals, and sparks. Accordion bellows are round, square or rectangular in shape and can be manufactured with a variety of end configurations and options. Round and square accordion bellows can have either four closed sides, or three open sides and one closed side. In terms of materials, accordion bellows are made from laminated polyester, treated synthetic fabric, polyvinyl chloride (PVC), aluminized glass fiber, rubber, foil ply rubber, and rubberized fabric. Some accordion bellows are sewn and stitched round while others are comprised of molded materials. Important dimensions to consider when selecting accordion bellows include retracted length, extended length, inside diameter or width, and height.

Accordion bellows feature several mounting or end configurations and may be tapered at both ends. For example, round bellows can have a round, straight end section for clamping to a screw, rod, or other component. With collars, the most common clamping method is a hose clamp. Accordion bellows can also have a flanged end section that is directed inwards radially, towards the center of the bellows, or a standard flange that is directed outwards radially, away from the center of the bellows. Bellows with flanged collars have a mounting flange at the end of a collar, not at the end of the bellows convolution. Vertically mounted, very long accordion bellows can be fitted with over-extension protection to prevent weight damage. Similarly, horizontally mounted accordion bellows can be fitted with support rings to prevent lifting screw thread engagement due to protective cover sag. 

Accordion bellows are available with armor plates, stiffeners, grommets, zippers, and hook and loop fasteners. Armor plates, which are typically made of stainless steel, protect bellows from hot chips, weld splatter, and other abrasives. Stiffeners made from PVC or other rigid materials are inserted into the convolutions of accordion bellows’ covers to provide rigidity and prevent sagging. Rubber grommets are used to hold the rod that guides and supports the bellows. Split accordion bellows can use either zippers or hook and loop fasteners for easy installation and removal. 

There are many applications for accordion bellows. For example, some round bellows are designed for use as expansion joints to allow movement due to service load, shock, or thermal cycles. Other bellows are designed to shield die set posts or for use in scissors, lift, or automatic guided vehicle (AGV) applications. Accordion bellows that protect screws prevent deposits from entering the screw jack and causing possible equipment damage or injury. Rounded bellows with way covers protect slide ways or rails, are rectangular or square, and are usually open on one side.

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