A structure of the hollow torque transmission member having a bellows portion in the middle section in the axial direction is manufactured at low cost by bulge molding such as hydroforming molding. A thin thickness portion having a smaller thickness in the radial direction than other portion is provided in the middle section in the axial direction of a hollow material. A hollow torque transmission member comprising a bellows portion is obtained by expanding the thin thickness portion outward in the radial direction by performing hydroforming molding to the hollow material.

A method for forming a conduit with a radial flange for forming part of a beaded coupling by: positioning a conduit blank in a forming die, wherein the forming die defines a radially extending recess; inserting a forming post in the conduit blank to define an annular space therebetween; inserting a flexible material in the annular space between the post and the conduit; placing a sleeve in a bearing relationship with the flexible material; compressing the flexible material between the post and the sleeve to force the flexible material against the conduit to expand the conduit outward into engagement with the radially extending recess in the forming die to form an annular flange; and releasing compression on the flexible material.

A method for forming a conduit with a radial flange for forming part of a beaded coupling by: positioning a conduit blank in a forming die, wherein the forming die defines a radially extending recess; inserting a forming post in the conduit blank to define an annular space therebetween; inserting a flexible material in the annular space between the post and the conduit; placing a sleeve in a bearing relationship with the flexible material; compressing the flexible material between the post and the sleeve to force the flexible material against the conduit to expand the conduit outward into engagement with the radially extending recess in the forming die to form an annular flange; and releasing compression on the flexible material.

A method is disclosed for pressure forming a metal preform including shock annealing of the preform and subsequently preheating the preform prior to pressure forming. Shock annealing may be carried out as differential shock annealing in which different regions of the preform are annealed to different degrees. Preheating may be carried out by differentially preheating, optionally shock preheating, different regions of the preform for preheating at least those regions of the preform which will be subject to elevated expansion during pressure forming. Shock annealing by induction heating can lower energy consumption, reduce processing times and allow for larger expansion of the preform.

A method is disclosed for pressure forming a metal preform including shock annealing of the preform and subsequently preheating the preform prior to pressure forming. Shock annealing may be carried out as differential shock annealing in which different regions of the preform are annealed to different degrees. Preheating may be carried out by differentially preheating, optionally shock preheating, different regions of the preform for preheating at least those regions of the preform which will be subject to elevated expansion during pressure forming. Shock annealing by induction heating can lower energy consumption, reduce processing times and allow for larger expansion of the preform.

A method is disclosed for pressure forming a metal preform including shock annealing of the preform and subsequently preheating the preform prior to pressure forming. Shock annealing may be carried out as differential shock annealing in which different regions of the preform are annealed to different degrees. Preheating may be carried out by differentially preheating, optionally shock preheating, different regions of the preform for preheating at least those regions of the preform which will be subject to elevated expansion during pressure forming. Shock annealing by induction heating can lower energy consumption, reduce processing times and allow for larger expansion of the preform.

A method is disclosed for pressure forming a metal preform including shock annealing of the preform and subsequently preheating the preform prior to pressure forming. Shock annealing may be carried out as differential shock annealing in which different regions of the preform are annealed to different degrees. Preheating may be carried out by differentially preheating, optionally shock preheating, different regions of the preform for preheating at least those regions of the preform which will be subject to elevated expansion during pressure forming. Shock annealing by induction heating can lower energy consumption, reduce processing times and allow for larger expansion of the preform.

A method for forming a conduit with a radial flange for forming part of a beaded coupling by: positioning a conduit blank in a forming die, wherein the forming die defines a radially extending recess; inserting a forming post in the conduit blank to define an annular space therebetween; inserting a flexible material in the annular space between the post and the conduit; placing a sleeve in a bearing relationship with the flexible material; compressing the flexible material between the post and the sleeve to force the flexible material against the conduit to expand the conduit outward into engagement with the radially extending recess in the forming die to form an annular flange; and releasing compression on the flexible material.

A method for forming a conduit with a radial flange for forming part of a beaded coupling by: positioning a conduit blank in a forming die, wherein the forming die defines a radially extending recess; inserting a forming post in the conduit blank to define an annular space therebetween; inserting a flexible material in the annular space between the post and the conduit; placing a sleeve in a bearing relationship with the flexible material; compressing the flexible material between the post and the sleeve to force the flexible material against the conduit to expand the conduit outward into engagement with the radially extending recess in the forming die to form an annular flange; and releasing compression on the flexible material.

A metal bellows for downhole use includes: a bellows capsule with a first end and a second end; an inner diameter side and an outer diameter side arranged between the first end and the second end; where the bellows capsule comprises a first bellows convolution and second bellows convolution and optionally additional bellows convolutions; and each bellows convolution comprises: a root on the inner diameter side of the bellows capsule; a first sidewall extending from the root toward the outer diameter side of the bellows capsule with a first connection point at the distal end; a second sidewall extending from the root toward the outer diameter side of the bellows capsule with a second connection point at the distal end and wherein the second sidewall is on the opposite side of the root as the first sidewall; wherein: the bellows convolutions are formed as a single piece; and the second sidewall connection point of the first bellows convolution is permanently affixed to the first sidewall connection point of the second bellows convolution.