Flow forming of composite material

A method of forming into a desired shape composite material that includes a matrix material which is reinforced with a fibrous material and which has a critical cure temperature, comprising:

• positioning a mold surface generally above and spaced from and facing a flexible membrane;
• heating the membrane to a forming temperature at which the matrix material will flow into the desired shape and which is below the critical cure temperature of the matrix material;
• laying the composite material on the membrane, and allowing the matrix material to be heated evenly by contact with the membrane;
• when the matrix material has been heated to said forming temperature, applying fluid pressure to the heated membrane opposite the mold surface to force the membrane and the material thereon to move upwardly into contact with and against the mold surface;
• while maintaining the fluid pressure, allowing the matrix material to flow and the composite material to take the desired shape and rotating the mold surface and membrane about a horizontal axis about 180.degree.;
• and
• then removing the fluid pressure from the membrane to allow the membrane to move out of contact with the composite material.

A method of forming into a desired shape composite material that includes a matrix material which is reinforced with a fibrous material and which has a critical cure temperature, comprising:

• positioning a mold surface generally above and facing a flexible membrane;
• heating the membrane to a forming temperature at which the matrix material will flow into the desired shape and which is below the critical cure temperature of the matrix material;
• laying the composite material on the membrane, and allowing the matrix material to be heated evenly by contact with the membrane;
• applying fluid pressure to the heated membrane opposite the mold surface to force the membrane and the material thereon upwardly against the mold surface;
• while maintaining the fluid pressure, allowing the matrix material to flow and the composite material to take the desired shape and rotating the mold surface and membrane about a horizontal axis about 180.degree.;
• then removing the fluid pressure from the membrane to allow the membrane to move out of contact with the composite material;
• and
• after allowing the membrane to move out of contact:
• moving the mold surface and the composite material formed thereon away from the membrane;
• positioning a second mold surface generally below and facing the membrane;
• rotating the second mold surface and the membrane about said axis about 180.degree. to position the second mold surface generally above and facing the membrane;
• laying unformed composite material on the membrane, and allowing said unformed material to be heated evenly by contact with the membrane;
• and
• repeating the steps of applying, maintaining, and then removing fluid pressure to form said unformed composite material.