Hydraulic molding is the most commonly used manufacturing method of metal
bellows at present. Metal corrugated culvert pipe manufacturer generally take multi - wave one
- time forming process.
(1) hydraulic molding process
Metal bellows hydraulic molding is divided into two stages. In the first stage, the pipe is restrained to expand under the action of liquid pressure in the pipe, and the degree of expansion is small, so that each forming intermediate template is positioned.
In the second stage, when the liquid pressure in the pipe is stable and equal to the bulging pressure, axial force is applied. Under the action of axial force and internal pressure, the pipe compresses and expands axially to make a metal bellows.
Axial compression bulging is adopted to improve the state of stress and strain in the bulging region, which is beneficial to plastic deformation and swelling coefficient.
(2) pressure control
The bulging pressure in the second stage of forming must be stable, and the pressure value is equal to the pressure value when constraining the bulging. If the bulging pressure is large, the blank will break. If the bulging pressure is too small, a concave wave is formed.
The size and shape of the hydroformed corrugated metal pipe can be formed into various waveforms according to the forming die. Compared with other bulging methods, the advantages of hydroforming are easy to get higher pressure, and the pressure action is uniform, control is relatively easy, the workpiece surface smooth, good quality; The disadvantage is that the forming device needs to be tightly sealed to prevent the bulging pressure and liquid leakage when the bulging.
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