Rockwell International Corporation

Ontario Technologies Corporation

David W Schulz

Edward D Weisert

Vene L Darby

Gail E Spaulding

Joseph R Goss

A fluidized bed of solid particulate material cools a heated workpiece through a temperature range critical to strength property determination. Upon immersion into the fluidized bed container the bed is allowed to collapse around the workpiece forming a universal fixture which firmly supports the workpiece for the remainder of the cooling, allowing cooling to be completed at a slower rate to prevent or minimize distortion caused from differential thermal contractions.

Method of cooling a heated workpiece utilizing a fluidized bed

A process is set forth for making a structure formed of at least two metallic workpiece sections each formed of a reactive metal. A mandrel having a nonreactive surface is sandwiched between the workpiece sections thereby preventing them from being in contact over a first selected area and allowing them to be in facing relation over a second selected area. A reactive metal contact is formed of the workpiece sections over the second selected area. The workpiece sections are maintained under coordinated temperature-pressure-time duration conditions to diffusion bond them at the second selected area. A gas pressure differential is applied between intermediate the workpiece sections and external of the workpiece sections to cause breakthrough at the first selected area and superplastic forming of at least one of the workpiece sections causing it to stretch in excess of its original surface area. The mandrel is removed from between the workpiece sections. The process provides structures such as airfoils having leading edges and trailing edges of controlled weight and internal radii.

Manufacturing method for hollow metal airfoil type structure

A method of making metallic sandwich structures is disclosed using a plurality of metal blank workpieces with at least one of the blank workpieces capable of being superplastically formed against a surface of a die. At least one of the blanks is treated at selective areas to prevent bonding in those areas. The blanks are positioned in a stack with at least one of the outer workpieces of the stack having the capacity to be superplastically formed. The stack is then diffusion bonded together in the untreated areas. At least one insert, preferably made from wax, is coupled to the bonded stack such that the external configuration of the at least one insert and bonded stack conform to the external configuration of the sandwich structure. A mold is cast around the at least one insert and bonded stack, after which the at least one insert is removed from the mold. Thereafter, the bonded stack is superplastically formed within the cast mold, resulting in the desired sandwich structure. In a second embodiment, wherein the metallic structure has a curvature, the stack may be either formed to the curvature of the sandwich structure and then diffusion bonded or simultaneously formed to the curvature of the sandwich structure and diffusion bonded in the untreated areas of the blanks. Thereafter, at least one insert is coupled to the curved and diffusion bonded stack, such that the combination has the external configuration of the sandwich structure to be formed. A mold is then cast about the curved and bonded stack and the at least one insert, after which the insert is removed from the mold. The curved and bonded stack is then superplastically formed in the cast mold to sandwich structure.

Low cost method of making superplastically formed and diffusion bonded

In a process for diffusion bonding of at least two metal workpieces of a reactive metal, particularly titanium, the improvement for expelling entrapped air from between surfaces of such workpieces prior to diffusion bonding, which comprises precoating the metal surfaces of the workpieces which are to be diffusion bonded with a substance capable of decomposing at a temperature above about 800.degree. F. and below the diffusion bonding temperature of the workpieces, e.g. of the order about 1300.degree. F., such substance being preferably polytetrafluoroethylene, to form an inert gas having a density greater than air, heating the workpieces to a temperature above about 800.degree. F. and causing decomposition or pyrolysis of such substance and forming an inert gas having a density greater than air, and flushing the inert gas together with the entrapped air out of contact with the surfaces of the workpieces, preferably by means of argon having a density greater than the pyrolysis products or the inert gas. The workpieces are further heated to cause diffusion bonding of the workpieces.

Method for expelling entrapped air from reactive metallic layups prior

A method for fabricating superplastically formed/diffusion bonded structures wherein metal blanks of aluminum or an aluminum alloy having an oxide surface layer are joined at selected areas by diffusion bonding and expanded superplastically to form a desired sandwich or integrally stiffened structure. According to such method, a suitable mask is applied to selected areas of the aluminum or aluminum alloy blanks. The assembly is then placed in a vacuum chamber and at a suitable low pressure and suitable voltage a glow discharge is created between the metal blank or blanks functioning as cathode or sputtering target, and an anode to selectively remove the oxide from the metal blanks and deposit the oxide debris on the anode. After the oxide layers have been removed from the surfaces of the blanks to be bonded, such surfaces are brought into intimate contact within the sputtering chamber or in an area equipped with heated platens, and while preventing reoxidation of the cleaned surface areas of the metal blanks, such blanks are subjected to press pressure and heat. The cleaned oxide-free areas bond, while the remaining areas, protected by the natural oxide and covered by the masks, do not bond. Such masks can be removed after sputtering and either prior to or during die bonding. If desired, the aluminum or aluminum alloy blanks can be initially anodized, to provide a thicker bond resistant oxide layer. The die bonded metal blanks are then subjected to superplastic forming in known manner to fabricate an integrally stiffened or sandwich structure.

Method for fabricating superplastically formed/diffusion bonded aluminum

An improvement to an apparatus for and method of making structures from at least one workpiece is disclosed. The prior art apparatus and method comprised a pair of dies which were clamped about the periphery of the at least one workpiece creating a gap therebetween. A pair of non-inflatable platens were then used to apply a force against the pair of dies further clamping the workpiece in place. The die assembly and workpiece were then heated to forming temperatures and thereafter the workpiece was formed within the pair of dies by fluid under pressure. Typically the forming was Superplastic Forming or Superplastic Forming/Diffusion Bonding. The improvement to the apparatus and method comprises providing an inflatable platen between one of the dies and one of the non-inflatable platens, adapted to regulate the force applied by said pair of dies to said at least one workpiece. A sensor, mounted within the gap is adapted to sense changes in the dimensions of the actual gap and provide a first output signal proportional thereto during the forming of the structure. A signal generator is provided for producing a second output signal proportional to a preferred gap dimension that is produced when said force is the minimum amount necessary for forming the at least one workpiece into the structure. A control system is provided to regulate the pressure level within the inflatable platen, and, therefore, the force applied to the pair of dies, using the first and second output signals such that the actual gap substantially equals the preferred gap during forming. In an alternate embodiment, a buffer platen is placed between the die assembly and inflatable platen to isolate the inflatable platen from the heat.

Method and apparatus for regulating preselected loads on forming dies

An improvement is disclosed to the method of making metallic structures from a plurality of stacked workpieces or blanks by joining first portions, preferably by diffusion bonding, of the stack and by clamping the joined stack at its periphery between forming members and superplastically forming second portions of said plurality of stacked blanks by the selective application of fluid under pressure. The improvement is a method of coupling the fluid to the second portions of the stack which comprises providing a first port through one of the outer blanks at the periphery of the stack. At least one stopoff path is provided for coupling the first port to the second portions of the stacked blanks, which are to be superplastically formed. A second port is provided in one of the forming members, which couples the first port to a source of pressurized fluid. Where there are at least three blanks in the stack, a slot is provided within the inner blank or blanks of the stack coupling the first port to the at least one stopoff path. Additionally, a hollow tubular member may be inserted into the slot. A hole is drilled through one wall of the tubular member, thus, coupling the interior thereof to the first port. In another embodiment, a groove in the second forming member aligned with the first port is provided, such that upon the application of pressure to the first port, the second blank is expanded within the groove forming an additional passageway coupling the first port to the at least one stopoff path.

Method of making diffusion bonded and superplastically formed structures

An improvement to an apparatus for and method of making structures from at least one workpiece is disclosed. The prior art apparatus and method comprised a pair of dies which were clamped about the periphery of the at least one workpiece creating a gap therebetween. A pair of non-inflatable platens were then used to apply a force against the pair of dies further clamping the workpiece in place. The die assembly and workpiece were then heated to forming temperatures and thereafter the workpiece was formed within the pair of dies by fluid under pressure. Typically the forming was Superplastic Forming or Superplastic Forming/Diffusion Bonding. The improvement to the apparatus and method comprises producing an inflatable platen mounted between one of the dies and one of the non-inflatable platens, adapted to regulate the force applied by said pair of dies to said at least one workpiece. A sensor is provided mounted within the gap adapted to sense changes in the dimensions of the actual gap and provide a first output signal proportional thereto during the forming of the structure. A signal generator is provided for producing a second output signal proportional to a preferred gap dimension that is produced when said force is the minimum amount necessary for forming the at least one workpiece into the structure. A control system is provided to regulate the pressure level within the inflatable platen, and, therefore, the force applied to the pair of dies, using the first and second output signals such that the actual gap substantially equals the preferred gap during forming. In an alternate embodiment, a buffer platen is placed between the die assembly and inflatable platen to isolate the inflatable platen from the heat.

Growing community of inventors

Hermosa Beach, CA, United States of America

David W Schulz