Nut forming apparatus

A forming and piercing apparatus comprising:

• a housing;
• a rotary block mounted in said housing for rotary movement about its central longitudinal axis and defining first and second parallel cylindrical bores extending parallel to said central axis and opening at diametrically opposed locations in a top face of said block;
• a set of two cylindrical members located in each bore in said rotary block;
• said cylindrical members having aligned longitudinal axes coaxial with said cylindrical bores and having contiguous end faces forming an interface;
• identical first and second dies respectively carried on a non-contiguous end face of the cylindrical member adjacent said top face;
• each of said dies having a bore coaxial with said cylindrical bore;
• an elongated piercing pin coaxially mounted in each die bore;
• coacting ramp means at the interface of each set of cylindrical members operative in one position of relative rotation of said members to preclude movement of the cylindrical member adjacent said top face in a direction away from said top face in its respective bore and operative in another position of relative rotation of said members to allow such movement;
• means operative to selectively rotate said rotary block between a first position, in which said first die is at a first die station and said second die is at a second die station, and a second position, in which said first die is at said second die station and said second die is at said first die station;
• a first punch mounted for coaction with a die positioned at said first die station;
• a second punch mounted for coaction with a die positioned at said second die station;
• and
• means operative in response to rotation of said rotary block to move said cylindrical members into said one position of relative rotation when the associated die is moved to said first die station, whereby to allow said first punch to deliver a forming blow to a blank positioned at that die, and to move said cylindrical members into said other position of relative rotation when the associated die is moved to said second die station, whereby to allow the associated piercing pin to backpierce a blank positioned at that die upon rearward movement of that die in response to a forming blow delivered by said second punch.