Hydroforming is a metal forming process that swells the material into a die using a high pressure fluid. This forming process is a practical demonstration of Pascal's Law, which states that external static pressure exerted on a fluid is distributed evenly throughout the fluid. This allows us to form complex shapes like the convolutions on a bellows with a high degree of consistency.  

Bellows Systems manufactures the widely known, Kopperman™ Bellows using this method. It is composed of a light gauge metal tube of one or more ply formed into a series of corrugations. Kopperman Expansion Joints can be manufactured with bellows formed from any material which has the necessary drawing quality, and the corrosion resistance required by the operating conditions of the system in which they might be installed. The standard Type 115 Non-Equalizing Expansion Joint utilizes a close-pitch single ply bellows. The standard Self-Equalizing Type 109 and Type 127 Expansion Joint utilizes an open-pitch single ply bellows. The pitch and depth of draw of any bellows can be varied and the shape modified to meet special application requirements. Multi-ply bellows are used primarily on small expansion compensators as standard equipment, and also on other large diameter Expansion Joints where significant reductions in compressive forces are desired. Extreme caution must be em loyed when specifying multl-ply bellows because they tend to be unstable under certain conditions. Torroidal bellows are very often used where extremely high pressure applications are encounterd.

Roll forming

Roll forming is a continuous shaping operation that involves slowly squeezing the material between a set of rollers to achieve a highly precise and uniform cross-sections. This forming technology can be used to produce metal bellows cross-sections with low tolerances. The bellows are first punched with a defined push set and then rolled to the required shape. 

Bellows Systems has the equipment to quickly convert a seam-welded tube into any configuration with the movements and spring rates best suited to your application. Our unique equipment and processes allow us to manufacture a variety of shapes including circular, rectangular and even oval shaped bellows in a single or multi-ply configuration. This process allows us to manufacture high volume of bellows efficiently.