What Is a Bellow?
A bellows is an object or device that can expand and contract, featuring two or more sides. This flexibility allows it to perform various functions.
Bellows used in cameras are typically made of black cloth or paper and have historically been employed as focusing devices for close-up photography.
Metal bellows, characterized by their elasticity and adjustability in length and position, are commonly used in joints as bendable metal pipes.
Bellows are extensively used in applications requiring high air tightness, such as high vacuum piping, compressor piping, and liquid nitrogen circulation systems.
Uses of Bellows
Camera bellows, once prevalent as focusing devices for close-up photography, have become less common with the advent of auto-focusing mechanisms.
Metal bellows serve as high-performance piping joints, valued for their elasticity, flexibility, and air tightness. They’re adjustable in both length and alignment.
Applications of bellows include:
- High vacuum systems in nuclear fusion and synchrotron radiation facilities
- Liquid nitrogen circulation system for superconductivity
- Control valves for compressors
- Accumulators in electronically controlled brake systems
Principle of Bellows
Camera bellows are typically made from thick, light-blocking black cloth or paper, and mounted in a way that allows precise expansion and contraction.
Metal bellows come in two main types: formed and welded bellows.
Formed bellows, produced by pressure-forming metal pipes, are cost-effective, suitable for mass production, and ideal for applications where high elasticity isn’t required.
Welded bellows, made by stacking metal washers and welding them together, offer high precision and elasticity with excellent pressure resistance but are more costly and less suited for mass production.
Materials such as aluminum, titanium, and stainless steel are used, varying in elasticity, pressure resistance, bending resistance, and durability.
Bellows are available in various sizes, bore diameters, and wall thicknesses. The appropriate type should be selected based on the specific application, material, and performance requirements.