Method for manufacturing billets, from metal powder, intended to be subsequently rolled or forged

Claim 1

A method for manufacturing metallic bodies intended to be subsequently machined into a desired shape by plastic deformation, comprising the steps of filling a sheath capsule with metal powder grains, sealing the capsule closed, heating the filled and sealed capsule at a heating station to a predetermined metal powder bonding temperature, and subjecting the filled and sealed capsule at the bonding temperature to a predetermined high pressure at a pressing station in the absence of external heat until the powder grains are bonded together to form a substantially solid body, the subjecting step comprising the steps of placing one end of the capsule at the bonding temperature on a layer of deformable and heat-insulating material in an over-sized forming cavity of a press which includes at least one movable punch, said material comprising unheated talc or pyrophyllite, an annular space being defined between said press and the capsule after insertion, filling said space with said deformable material in powder or grain form with the capsule in said press, and covering a layer of said material over the opposite end of the capsule so as to completely surround the capsule, whereby said deformable material completely fills said space and influences the capsule isostatically during the subjecting step to thereby effect the application of pressure completely against all sides of the capsule such that any folding or corrugating of the capsule sheath is substantially avoided, and whereby said deformable material has the necessary heat-insulating characteristic such that equalization of the temperature within the capsule is brought about by delaying the compressing thereof until the surface layer, which may have cooled between said heating and subjecting steps, has been re-heated by heat transfer from the inner portion of the capsule.

Claim 2

A method for manufacturing metallic bodies intended to be subsequently machined into a desired shape by plastic deformation, comprising the steps of filling a sheath capsule with metal powder grains, sealing the capsule closed, heating the filled and sealed capsule at a heating station to a predetermined metal powder bonding temperature, and subjecting the filled and sealed capsule at the bonding temperature to a predetermined high pressure at a pressing station in the absence of external heat until the powder grains are bonded together to form a substantially solid body, the subjecting step comprising the steps of placing one end of the capsule at the bonding temperature on a layer of deformable and heat-insulating material in an over-sized forming cavity of a press which includes at least one movable punch, said material comprising unheated talc or pyrophyllite, an annular space being defined between said press and the capsule after insertion, filling said space with said deformable material in powder or grain form with the capsule in said press, and covering a layer of said material over the opposite end of the capsule so as to completely surround the capsule, whereby said deformable material completely fills said space and influences the capsule isostatically during the subjecting step to thereby effect the application of pressure completely against all sides of the capsule such that any folding or corrugating of the capsule sheath is substantially avoided, and whereby said deformable material has the necessary heat-insulating characteristic such that equalization of the temperature within the capsule is brought about by delaying the compressing thereof until the surface layer, which may have cooled between said heating and subjecting steps, has been re-heated by heat transfer from the inner portion of the capsule.

Claim 4

A method for manufacturing metallic bodies intended to be subsequently machined into a desired shape by plastic deformation, comprising the steps of filling a sheath capsule with metal powder grains, sealing the capsule closed, heating the filled and sealed capsule at a heating station to a predetermined metal powder bonding temperature, and subjecting the filled and sealed capsule at the bonding temperature to a predetermined high pressure at a pressing station in the absence of external heat until the powder grains are bonded together to form a substantially solid body, the subjecting step comprising the steps of placing one end of the capsule at the bonding temperature on a layer of deformable and heat-insulating material, said material comprising unheated talc or pyrophyllite, inserting the capsule with said layer into an over-sized forming cavity of a press which includes a pair of punches with at least one thereof being movable relative to the other, an annular space being defined between said press and the capsule after insertion, filling said space with said deformable material in powder or grain form with the capsule in said press, and covering a layer of said material over the opposite end of the capsule, so as to completely surround the capsule, whereby said deformable material completely fills said space and influences the capsule isostatically during the subjecting step to thereby effect the application of pressure completely against all sides of the capsule such that any folding or corrugating of the capsule sheath is substantially avoided, and whereby said deformable material has the necessary heat-insulating characteristic such that equalization of the temperature within the capsule is brought about by delaying the compressing thereof until the surface layer, which may have cooled between said heating and subjecting steps, has been re-heated by heat transfer from the inner portion of the capsule.

Claim 5

A method for manufacturing metallic bodies intended to be subsequently machined into a desired shape by plastic deformation, comprising the steps of filling a sheath capsule with metal powder grains, sealing the capsule closed, heating the filled and sealed capsule at a heating station to a predetermined metal powder bonding temperature, and subjecting the filled and sealed capsule at the bonding temperature to a predetermined high pressure at a pressing station in the absence of external heat until the powder grains are bonded together to form a substantially solid body, the subjecting step comprising the steps of placing one end of the capsule at the bonding temperature on a layer of deformable and heat-insulating material, said material comprising unheated talc or pyrophyllite, inserting the capsule with said layer into an over-sized forming cavity of a press which includes a pair of punches with at least one thereof being movable relative to the other, an annular space being defined between said press and the capsule after insertion, filling said space with said deformable material in powder or grain form with the capsule in said press, and covering a layer of said material over the opposite end of the capsule, so as to completely surround the capsule, whereby said deformable material completely fills said space and influences the capsule isostatically during the subjecting step to thereby effect the application of pressure completely against all sides of the capsule such that any folding or corrugating of the capsule sheath is substantially avoided, and whereby said deformable material has the necessary heat-insulating characteristic such that equalization of the temperature within the capsule is brought about by delaying the compressing thereof until the surface layer, which may have cooled between said heating and subjecting steps, has been re-heated by heat transfer from the inner portion of the capsule.