Method and apparatus for manufacturing a stop and lock shoulder for a blind fastener sleeve

For a two piece blind fastener for securing a plurality of workpieces comprising

• a hollow sleeve having a through bore, the sleeve having a sleeve shank portion and an enlarged sleeve head at one end.
• a pin,
• the pin having a shank portion and an enlarged pin head with the pin shank portion adapted to be located within the bore of the sleeve and with the pin head located at the end of the sleeve shank portion opposite the sleeve head,
• the through bore of the sleeve having a reduced diameter bore portion defining a radially inwardly extending sleeve stop shoulder,
• the pin having a pin stop shoulder,
• a lock groove located on the pin,
• the pin head adapted to engage the sleeve shank portion and to deform the same to form a blind head opposite the sleeve head in response to a relative axial force applied between the pin and the sleeve,
• the sleeve stop shoulder having at least a portion thereof radially separated from the radially confronting portion of the sleeve,
• the pin stop shoulder adapted to engage the sleeve stop shoulder for directing the material of the sleeve stop shoulder radially inwardly into the lock groove to lock the pin and sleeve together,
• the method of forming the sleeve stop shoulder including the steps of
• forming a sleeve blank to have the enlarged sleeve head and to have the through bore and reduced diameter bore portion with the juncture therebetween defining a radially inwardly extending shoulder forming portion,
• providing a piercing pin to have an enlarged shoulder portion,
• a forming land and a tapered portion located between the shoulder portion and the forming land, the enlarged shoulder portion being of a diameter generally that of the sleeve through bore and the forming land being of a diameter generally that of the reduced diameter bore portion and with the tapered portion defining a cavity between the enlarged shoulder and forming land,
• moving the piercing pin into the through bore of the sleeve blank and engaging the sleeve shoulder forming portion with the enlarged shoulder to deform the material of the sleeve shoulder forming portion radially inwardly into the cavity of the tapered portion,
• removing the piercing pin from the sleeve blank while deforming the material in the cavity of the tapered portion radially outwardly to form the sleeve stop shoulder with at least a portion radially separated from the radially confronting portion of the sleeve.

For a two piece blind fastener for securing a plurality of workpieces comprising a hollow sleeve having a through bore, the sleeve having a sleeve shank portion and an enlarged sleeve head at one end, a pin, the pin having a shank portion and an enlarged pin head with the pin shank portion adapted to be located within the bore of the sleeve and with the pin head located at the end of the sleeve shank portion opposite the sleeve head, the through bore of the sleeve having a reduced diameter bore portion defining a radially inwardly extending sleeve stop shoulder, the pin having a pin stop shoulder, a lock groove located on the pin, the pin head adapted to engage the sleeve shank portion and to deform the same to form a blind head opposite the sleeve head in response to a relative axial force applied between the pin and the sleeve, the sleeve stop shoulder having at least a portion thereof radially separated from the radially confronting portion of the sleeve, the pin stop shoulder adapted to engage the sleeve stop shoulder for directing the material of the sleeve stop shoulder radially inwardly into the lock groove to lock the pin and sleeve together, apparatus for forming the sleeve stop shoulder comprising a piercing pin having an enlarged shoulder portion, a forming land and a tapered portion located between said shoulder portion and said forming land, said enlarged shoulder portion being of a diameter generally of the sleeve through bore, said forming land being of a diameter generally that of the reduced diameter bore portion, said tapered portion defining a cavity having a preselected volume generally equal to that of the radially separated portion of the sleeve stop shoulder.