Rockwell International Corporation

United States of America As Represented by the Secretary of the Air Force

Delaware Corporation

Roger S Raymond

Charles Howard Hamilton

Charles Dowling

Fred B Koeller

Martin Goldberg

Method for eliminating core distortion in diffusion bonded and superplastically formed structures or panels, wherein metal blanks or workpieces of metal, capable of diffusion bonding and superplastic forming such as a titanium alloy, preferably in the form of thin sheets of the order of 0.030 inch thick or less, are placed in contact with each other in a tooling apparatus or die, the sheets are joined at selected areas by diffusion bonding and are then expanded superplastically to form a desired panel or a truss core panel structure. In such method, the metal sheets are diffusion bonded at certain preselected areas under pressure and at elevated temperature, and the unbonded areas of the sheets are then expanded by superplastic forming into contact with the walls of the tool or die cavity, at elevated temperature e.g., 1600-1650.degree. F. and an internal gas pressure e.g., about 300 psi, to form the desired panel. Following superplastic forming and cooling, the thin cell walls of the core panel are often distorted or crushed. As a feature of the invention, following superplastic forming and release of the internal gas pressure, and during cooling of the panel and while the metal panel is still at a temperature where the metal remains flexible or plastic, e.g., 1200.degree.-1400.degree. F., a low internal differential gas pressure, e.g., of about 3-7 psi, is introduced into the interior of the panel, expanding the panel out to its original form against the tool or die as a restraint, and straightening the thin core cell walls of the panel which were distorted following superplastic forming.

Method of eliminating core distortion in diffusion bonded and

An improved insulated forming press for forming structures at elevated temperatures and pressures is disclosed. Vertical rams move vertical heated platens, vertical ram insulation blocks, and vertically oriented forming dies, to close about a workpiece. The workpiece, insulation blocks, platens, and dies are supported by two sets of interlocking support members. One ram is activated by a plurality of mechanical jack screws, and the other is activated by a plurality of hydraulic cylinders that utilize a nonflammable mixture of water glycol. After forming is completed, the tooling can be automatically separated by retracting the rams and the workpiece is removed vertically.

Veritcal press

An improved apparatus and forming method is disclosed for making laminate structures from a stack of worksheets using superplastic forming and diffusion bonding. A fluid line is inserted into the forming die which is connected to the stack by a slot in one sheet. A sheet is coated with a stopoff material to prevent bonding of selected areas of the sheets. The slot is positioned adjacent to the stopoff path and an inflation tube having an internal bore is inserted into the slot. The tube material is noncontaminating relative to the worksheet materials, and the tube material has a high compressive strength sufficient to form a groove in one worksheet without diminishing the bore area. When the tube is thicker than the sheet having the slot in it and the tube is subjected to compressive forces by the forming die, the tube acts as a male die and pushes out a groove in a surrounding worksheet without substantially changing the structure of the tube. Gas is fed into the fluid line, and into the stack of sheets creating a pressure differential within the stack for diffusion bonding and superplastic forming.

Apparatus and method for making laminate structures

Method for producing structures from metal workpieces which may or may not be capable of superplastic forming, such as titanium alloy and steel, using a forming die having a predetermined contour or shape and a cooperating pressure diaphragm formed of a metal capable of superplastic forming. Fluid pressure is applied to one side of the pressure diaphragm to cause stretching or expansion thereof by superplastic forming, and forcing the diaphragm against the workpiece, which in turn is caused to move or expand into contact with the forming die, to produce a structural component of predetermined shape. With the proper application of pressure, temperature and time, metal parts, e.g. 8 to 12 inches thick, can be formed in addition to parts formed from comparatively thin sheet metal.

Method for forming structural parts

Apparatus for heat flattening and/or forming titanium sheet material under heat and pressure using thermoclamps fabricated of materials having different thermal expansion properties. Upper and lower dies are made of one alloy having a large thermal expansion while tie bars between the two dies are made of an alloy having low thermal expansion. During heat cycles, the difference in expansion causes the tie bars to close the gap between the dies and apply pressure to the titanium sheet between. In an alternate arrangement, the thermal clamping action coins a bead into a diaphragm to make a vacuum tight seal so that the atmospheric pressure in the oven produces the forming or flattening of the sheet.

Thermoclamps

Metals such as titanium alloy blanks which are subject to contamination by air at elevated temperatures are precision formed into desired shapes in a controlled environment. The metal worksheet and a shaping member are located within an enclosure. An inert gas environment is provided in the enclosed area. The metal worksheet is heated to a suitable forming temperature and stretched substantially in excess of its original surface area under tensile stress from a fluid pressure loading and formed into the desired shape by interaction with the shaping member. Novel sealing arrangements for the enclosed area of the forming apparatus are provided.

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Redondo Beach, CA, United States of America

Roger S Raymond