Forging process

Abstract

Process for manufacturing a forged article in which a preform is generated by filling a semi-rigid liner with powdered metal, providing the liner with a sealing element, and isostactically compressing the liner and its contents. The liner is then removed from the green preform, the preform is sintered, and the resulting sintered preform is forged.

The invention having been thus described, what is claimed as new and desired to secure by Letters Patent is: .[.1. A process for forming a workpiece of a predetermined shape from powdered metal, comprising the steps of: 
     
        contents and closed by a portion of the press before pressing..]. .[.2.  A process for forming a workpiece of a predetermined shape from powdered metal, comprising the steps of: (a) forming a semi-rigid liner of heat-decomposible material having generally the said shape,   (b) adding a quantity of said powdered metal into the liner,   (c) providing the liner with a liquid-impervious sealing element which completely envelops it,   (d) isostatically compacting the sealing element, the liner and the contents,   (e) heating the liner and contents to cause decomposition of the liner and sintering the contents, and   (f) forging the contents, wherein the liner is made of a foamed polymer in which the bubbles can collapse permanently during the compacting step..]. .[.3. A process for forming a workpiece of a predetermined shape from powdered metal, comprising the steps of:   (a) forming a semi-rigid liner of heat-decomposible material having generally the said shape, the liner being formed of a foamed polymer,   (b) adding a quantity of said powdered metal into the liner,   (c) providing the liner with a liquid-impervious sealing element which completely envelops it,   (d) isostatically compacting the sealing element, the liner and the contents,   (e) heating the liner and contents to cause decomposition of the liner and sintering the contents, and   (f) forging the contents, wherein the sealing element is a thin elastomer bag in which the liner is enclosed, which bag is removed before the liner   
     
     
        and contents are heated..]. .Iadd.4.  A process for forming a workpiece of a predetermined shape from powdered metal, comprising the steps of: (a) forming a semi-rigid liner of heat-decomposible material having generally the said shape,   (b) adding a quantity of said powdered metal into the liner,   (c) inserting the liner and contents into the open end of an elastomeric liquid-impervious bag which forms part of an isostatic press provided with means for sealing the open end of the bag,   (d) sealing the open end of the bag,   (e) isostatically compacting the bag against the liner so that the bag completely envelops the liner to compact the powdered metal in the liner,   (f) removing the liner and contents from the bag,   (g) heating the liner and contents to cause decomposition of the liner and sintering the contents to form a rough workpiece, and   
     
     
       (h) forging the rough workpiece. .Iaddend. .Iadd.5.  A process for forming a workpiece of a predetermined shape from powdered metal, comprising the steps of: (a) forming a semi-rigid liner of heat-decomposible foamed polymer having generally the said shape,   (b) adding a quantity of said powdered metal into the liner,   (c) inserting the liner and contents into an elastomeric liquid-impervious sealing element,   (d) isostatically compacting the bag against the liner so that the sealing element completely envelops the liner to compact the powdered metal in the liner,   (e) removing the liner and contents from the sealing element,   (f) heating the liner and contents to cause decomposition of the liner and sintering the contents to form a rough workpiece, and   (g) forging the rough workpiece. .Iaddend. .Iadd.6. A process for forming a workpiece of a predetermined shape from powdered metal, comprising the steps of:   (a) forming a semi-rigid liner of heat-decomposible foamed polymer having generally the said shape,   (b) adding a quantity of said powdered metal into the liner,   (c) inserting the liner and contents into an elastomeric liquid-impervious bag,   (d) isostatically compacting the bag against the liner so that the bag completely envelops the liner to compact the powdered metal in the liner,   (e) removing the liner and contents from the bag,   (f) heating the liner and contents to cause decomposition of the liner and sintering the contents to form a rough workpiece, and   
     
     
       (g) forging the rough workpiece. .Iaddend. .Iadd.7.  A process for forming a workpiece of a predetermined shape from powdered sinterable material for mechanical finishing, comprising the steps of: (a) forming a semi-rigid liner of heat-decomposible material having generally the said shape,   (b) adding a quantity of said powdered material into the liner,   (c) inserting the liner and contents into the open end of an elastomeric liquid-impervious bag which forms part of an isostatic press provided with means for sealing the open end of the bag,   (d) pressurizing the press to force the bag against the liner so that the bag completely envelops the liner to compact the powdered material in the liner,   (e) removing the liner and contents from the bag, and   (f) heating the liner and contents to cause decomposition of the liner and   
     
     
        sintering the contents to form a rough workpiece. .Iaddend. .Iadd.8.  A process for forming a rough workpiece of a predetermined shape from powdered sinterable material for mechanical finishing, comprising the steps of: (a) forming a semi-rigid liner of heat-decomposible foamed polymer having generally the said shape,   (b) adding a quantity of said powdered material into the liner,   (c) inserting the liner into an elastomeric liquid-impervious sealing element,   (d) isostatically pressurizing the sealing element and the contents so as to force the sealing element against the liner so that the sealing element completely envelops the liner to permanently collapse the bubbles of the foamed polymer and to compact the powdered material in the liner,   (e) removing the liner and contents from the sealing element, and   (f) heating the liner and contents to cause decomposition of the liner and   
     
     
        sintering the contents to form a rough workpiece. .Iaddend. .Iadd.9.  A process for forming a rough workpiece of a predetermined shape from powdered sinterable material for mechanically finishing, comprising the steps of: (a) forming a semi-rigid liner of heat-decomposible foamed polymer having generally the said shape,   (b) adding a quantity of said powdered material into the liner,   (c) enclosing the liner within a liquid-impervious elastomer bag,   (d) isostatically pressurizing the bag so that the bag completely envelops the liner and contents to force the bag against the liner and to compact the powdered material in the liner,   (e) removing the bag and heating the liner and contents to cause decomposition of the liner and sintering the contents to form a rough workpiece. .Iaddend.