Abstract: The multi-ram forge can form the parts with complex shape, especially with hollow or concavo-convex feature, within single heating and single stroke. The properties of forged parts are higher than those by conventional close die forge process. The multi-ram forge process will also save the material and machining time. So, it could be regarded as a green forge technique with high accuracy and quality, saving energy and material. But the development of heavy multi-ram forge hydraulic presses, which will provide the huge vertical and horizontal forging or piercing forces to producing large or middle size parts, is a big engineering challenge compared to the conventional forge press. Based on the prestressed wire-wound technique, a novel orthogonal preload frame is proposed, which could provide vertical and horizontal preloads simultaneously to prevent the multi-way forging or piercing forces with the prestressed wire wounding along the special designed frame contour. The new frame structure has been investigated in the development of a 40 MN/64 MN multi-ram forge hydraulic press, whose frame is designed as an orthogonal preload frame. This breakthrough provides the fundamental technology for implementing the multi-ram forge process in China, and will promote the technical progresses to save energy and reduce emission for Chinese forge industry.

Key words: Forging machines, Landing gear, Metal forming, Prestressing, Valve