Bellows for sensorsThe manufacturing method

In our life, there are many pipes with telescopic function, which can be expanded and folded freely, and it is very convenient to use. For example, the drain pipe of the washing machine, the straw in the milk tea cup, etc., are all these pipes, but the common diameters of these pipes are relatively small and short, and there is also a bellows for sensors with a diameter of several meters or even longer. I have always been curious about the concave and convex surface of such a large pipe and how it is made.

The bellows for the sensor is a concave-convex shell on the surface, like a series of corrugations, so it is called the bellows for the sensor. Due to their soft and flexible characteristics, they have been widely used in chemical engineering, electronics, electric power, civil engineering, aerospace and other engineering equipment to play a role in sealing, isolation, noise reduction, drainage, etc. Humans have been looking for flexible hoses that can stretch and fold. In ancient times, people first made tubular structures from the skin seams of animals.

According to the material classification, the sensor bellows is mainly divided into metal sensor bellows and plastic bellows.

Plastic bellows is a flexible tubular product made of plastic. Due to the advantages of material saving, light weight and excellent physical and chemical properties, plastic corrugated pipes have been widely used in civil construction, municipal engineering, highway bridges and other fields.

The metal bellows is a bellows. Common metal bellows are carbon steel, stainless steel or plastic inner layer and plated metal outer layer. Metal bellows can be used for small-angle turning, transmission, expansion, and are widely used in electric power, machinery and other industries.

According to the classification of forming process, bellows can be divided into hydraulic forming bellows, rolling forming bellows, mechanical expansion bellows and deposition forming bellows.

Hydroforming is a common and widely used forming method for bellows. Mainly used in the manufacture of ring corrugated pipe, can form a wall thickness of 0.08~4mm corrugated pipe. Hydroforming uses the liquid pressure in the tube blank to expand and then compress the pipe to form the bellows. Small diameter metal bellows mostly use this forming process.

The roll forming process is based on the rolling of the forming wheel in the tube blank. Some bellows can only push out one bellows at a time, and some bellows can push out several bellows at a time. This process is mainly used to manufacture large corrugated pipes.

Deposition modeling is the deposition of bellows material on the mold core, and then dissolving the mold core. This process is usually used to manufacture metal bellows with low hardness, and the manufacturing cost is also high. I can often see large, long pipes pulled by trucks on the road, with many bellows on the surface. I want to know how this pipe is made.

This large pipe is called a porous bellows. It has become the main product of drainage in civil engineering construction. It is also widely used in highway, municipal engineering and sports fields. Let's see how buried bellows are made.

The perforated corrugated pipe is made of a single extrusion molding process, and the raw materials are mostly made of high density polyethylene (HDPE) plastic. This material has strong corrosion resistance and long service life. In the production process, the prepared polyethylene plastic and some additives are put together and sent to the machine for full mixing.