An annular reference surface is formed around a through-hole of an eye portion. A distal-end-side curved portion is formed at a first corner portion, on an outer side of the annular reference surface. The thickness of the distal-end-side curved portion is reduced in a range of a length from the first flat surface toward the distal end surface. A hole-side curved portion whose thickness is reduced toward an inner surface of the through-hole is formed at a second corner portion, on an inner side of the annular reference surface. The length of the hole-side curved portion is less than the length of the distal-end-side curved portion. The hole-side curved portion is curved with a greater curvature than that of the distal-end-side curved portion.

An annular reference surface is formed around a through-hole of an eye portion. A distal-end-side curved portion is formed at a first corner portion, on an outer side of the annular reference surface. The thickness of the distal-end-side curved portion is reduced in a range of a length from the first flat surface toward the distal end surface. A hole-side curved portion whose thickness is reduced toward an inner surface of the through-hole is formed at a second corner portion, on an inner side of the annular reference surface. The length of the hole-side curved portion is less than the length of the distal-end-side curved portion. The hole-side curved portion is curved with a greater curvature than that of the distal-end-side curved portion.

A progressive former having a bolster and a ram reciprocal towards and away from the bolster, a plurality of workstations evenly spaced across the bolster and ram including aligned tooling piece holders on the bolster and ram, cylindrical die cases in the tooling holders on the bolster and cylindrical tool cases in the tooling holders on the ram, the tooling cases at the workstations being coaxial, a sideways forming mechanism at one of said workstations, the mechanism including a cam and a cam follower radially outward of imaginary outward projections of the associated tooling cases, the cam follower being arranged to be activated by forward motion of the ram towards the bolster, the mechanism including a tool for forming the blank by applying a sideways force on the blank.

A progressive former having a bolster and a ram reciprocal towards and away from the bolster, a plurality of workstations evenly spaced across the bolster and ram including aligned tooling piece holders on the bolster and ram, cylindrical die cases in the tooling holders on the bolster and cylindrical tool cases in the tooling holders on the ram, the tooling cases at the workstations being coaxial, a sideways forming mechanism at one of said workstations, the mechanism including a cam and a cam follower radially outward of imaginary outward projections of the associated tooling cases, the cam follower being arranged to be activated by forward motion of the ram towards the bolster, the mechanism including a tool for forming the blank by applying a sideways force on the blank.

An annular reference surface is formed around a through-hole of an eye portion. A distal-end-side curved portion is formed at a first corner portion, on an outer side of the annular reference surface. The thickness of the distal-end-side curved portion is reduced in a range of a length from the first flat surface toward the distal end surface. A hole-side curved portion whose thickness is reduced toward an inner surface of the through-hole is formed at a second corner portion, on an inner side of the annular reference surface. The length of the hole-side curved portion is less than the length of the distal-end-side curved portion. The hole-side curved portion is curved with a greater curvature than that of the distal-end-side curved portion.

A progressive former having a bolster and a ram reciprocal towards and away from the bolster, a plurality of workstations evenly spaced across the bolster and ram including aligned tooling piece holders on the bolster and ram, cylindrical die cases in the tooling holders on the bolster and cylindrical tool cases in the tooling holders on the ram, the tooling cases at the workstations being coaxial, a sideways forming mechanism at one of said workstations, the mechanism including a cam and a cam follower radially outward of imaginary outward projections of the associated tooling cases, the cam follower being arranged to be activated by forward motion of the ram towards the bolster, the mechanism including a tool for forming the blank by applying a sideways force on the blank.

A progressive former having a bolster and a ram reciprocal towards and away from the bolster, a plurality of workstations evenly spaced across the bolster and ram including aligned tooling piece holders on the bolster and ram, cylindrical die cases in the tooling holders on the bolster and cylindrical tool cases in the tooling holders on the ram, the tooling cases at the workstations being coaxial, a sideways forming mechanism at one of said workstations, the mechanism including a cam and a cam follower radially outward of imaginary outward projections of the associated tooling cases, the cam follower being arranged to be activated by forward motion of the ram towards the bolster, the mechanism including a tool for forming the blank by applying a sideways force on the blank.

There is provided a piercing apparatus in which the occurrence of an inner surface flaw in a hollow shell is suppressed. A piercing apparatus (10) according to an embodiment of the present invention is the piercing apparatus (10) which pierces a billet (18). The piercing apparatus (10) has a plug (14). The plug (14) has a through hole (30). The through hole (30) extends along the central axis, and allows the central portion of the billet (18) being pierced to pass therethrough.

There is provided a piercing apparatus in which the occurrence of an inner surface flaw in a hollow shell is suppressed. A piercing apparatus (10) according to an embodiment of the present invention is the piercing apparatus (10) which pierces a billet (18). The piercing apparatus (10) has a plug (14). The plug (14) has a through hole (30). The through hole (30) extends along the central axis, and allows the central portion of the billet (18) being pierced to pass therethrough.