The British Group Rhodes has developed a breakthrough new process that can ensure that large single-shell components can more accurately maintain their shape during cooling, which is very suitable for superplastic forming (SPF) of thin-walled parts.
Superplastic forming is a precision forming method that can accurately form single or multiple metal sheets into more complex, strong, lightweight structures, thereby improving the integrity of the component. Superplastic forming requires heating the sheet to a specific precise temperature and then controlling the air pressure to form the sheet in a mold.
The superplastic forming of the single shell component needs to diffusely connect multiple layers of sheet material at a specific position, and then fill it with argon to superplasticize the sheet material to expand the sheet material into the shape of a hollow mold. This process is very sensitive to temperature and pressure. When external argon is charged into the high-temperature component, it will increase its volume due to the expansion of the gas. If the control is insufficient, the pressure will increase. One of the most critical steps during the pressure cycle is the need to remove the formed components from the press after cooling and forming after inflation. In addition, the component should be purged with low pressure argon gas to ensure that the inner surface does not produce oxidation under high temperature conditions. If the purge pressure is too high, the component will expand and deform excessively. The purge pressure is too low, and atmospheric pressure can cause the component to collapse internally. During the cooling process, because the temperature of the charged gas decreases, the volume decreases, and the gas pressure inside the module decreases, it becomes very difficult to balance the air pressure. Although fine-tuning compensation can be based on experience, various external factors are more difficult to control. One of the important external factors is atmospheric pressure. Fluctuations in external air pressure will have a significant impact on the final shape of the component and cause tolerance deviations, making the formation of large-size thin-walled parts more difficult.
This major process improvement provides a unique and efficient solution for the formation of complex thin-walled components. No matter how thin the material is and how unstable the atmospheric conditions are, it can ensure the formation and shape retention of large components. The new process uses the principle of a barometer: a vertical, open vent tube is used to balance the air pressure, which ensures that the low-pressure gas is constant, allowing it to automatically compensate for changes in air pressure, so that the material maintains a constant shape after molding in the mold. This new method of air pressure control can more accurately shape complex structures and better control multilayer diffusion connections. Since the mid 1970s, the Rhodes Group has been at the forefront of superplastic forming equipment. The Rhodes Group is the only British company that can develop automatic superplastic forming equipment for use in products. This innovation from the Rhodes Group opens up opportunities for applications in the aerospace and automotive industries, and is currently applying for a patent