Bellows are tubular elastic sensing elements connected by folding corrugated sheets along the direction of folding and stretching. Bellows are widely used in instruments and meters. They are mainly used as measuring elements for pressure measuring instruments to convert pressure into displacement or force. Bellow has thin wall and high sensitivity. The measuring range is from tens of PA to tens of MPa. Its open ends are fixed, the sealing ends are in free state, and the auxiliary springs or springs are used to increase elasticity. When working, under the action of internal pressure, it stretches along the length of the pipe, so that the movable ends move with the pressure. The movable end can drive the pointer to directly indicate the size of the pressure. Bellows are often combined with displacement sensors to form a pressure sensor that outputs electricity, and sometimes used as an isolating element. Because the expansion of bellows requires larger volume changes, the response speed of bellows is lower than that of Bourdon tube. The bellows are suitable for measuring low pressure.
Bellows mainly include metal bellows, corrugated expansion joints, corrugated heat exchangers, diaphragm membrane boxes and metal hoses. Metal bellows are widely used in petrochemical, instrument, aerospace, automobile, ship, motor, chemical, electric, cement, metallurgy and other industries. Plastic and other materials bellows have an irreplaceable role in media delivery, power cord, machine tools, home appliances and other fields. Automotive bellows
play a great role in our life.