There are many ways to form metal bellows, such as hydraulic forming, mechanical or rubber expansion forming, edge welding forming, electrodeposition forming, spinning forming, roll forming, etc.
Different moldings have their own advantages and disadvantages, and the hydroformed bellows is the bellows with the best comprehensive performance.
SS bellows manufacturers will choose the molding method based on customer requirements and the company’s resources.
Hydroformed bellows are metal bellows formed by injecting a liquid medium with a certain pressure inside the metal pipe to make the metal pipe expand and deform according to the externally fixed bellows forming mold.
It is the most widely used one among the many metal bellows forming methods.
Hydroformed bellows are mainly used for processing stainless steel, low-carbon steel, copper alloy, and other materials with good plasticity at room temperature.
There are three main forming methods of hydroformed bellows on the market. They are integral hydroforming, single convolution continuous hydroforming, and Fully automatic integral hydroforming.
Integral hydroforming
The metal pipe is placed in the corrugated pipe forming mold, and then both ends of the metal pipe are sealed.
Inject high-pressure emulsion into the metal pipe, and when the internal pressure reaches the yield strength of the metal material, the metal pipe between the two forming dies will expand outward.
When the expansion reaches the designed corrugation radian, remove the auxiliary gasket between the corrugated pipe forming dies, apply axial pressure on the corrugated pipe from top to bottom, and the metal pipe will be axially compressed according to the designed corrugated pipe forming die shape forming.
Most integral hydroforming processes require manual operation, and the work efficiency is relatively low.
Currently, it is mainly used to produce large-diameter bellows.
Single convolution continuous hydroforming
As the market’s requirements for bellows are getting longer and longer, people have created a single convolution continuous forming machine for bellows.
It can increase or decrease the convolution number within the range allowed by the length of the metal pipe to freely adjust the length of the bellows.
At the same time, it can also change the convolution height and distance of the bellows and then adjust the performance of the bellows.
This bellows-forming method is often used for small-sized bellows, such as DN300 and below.
It is the most mainstream bellows forming method in the current market.
The number of corrugated pipe layers produced by a single convolution continuous molding machine is at most two layers.
Fully automatic integral hydroforming
It changes the mold installation and disassembly process in traditional hydraulic integral forming from manual to fully automatic.
It is an advanced hydraulic forming method that has only appeared in recent years.
The cost of fully automatic hydraulic integral forming equipment is high, the forming mold is automatically opened and closed, and the production efficiency is very high.
It is dedicated to the mass production of precision bellows with small sizes and fixed specifications.
