Thread Forming Apparatus And Associated Method

Abstract

A thread forming apparatus includes a punch mechanism including a punch shaft and a cylindrical punch having a plurality of circumferentially spaced-apart punch projections, the punch mechanism being structured to be moved radially and rotate continuously about the rotation axis of the punch mechanism in a first direction; a die mechanism including a die shaft and a cylindrical die having a plurality of circumferentially spaced-apart die recesses, the die mechanism being structured to be moved radially and rotate continuously about the rotation axis of the die mechanism in a second direction opposite the first direction; and an actuator connected to the punch shaft and the die shaft and structured to rotate and radially move the punch mechanism and the die mechanism relative to a central axis of a can body for forming a plurality of threads on the can body.

What is claimed is: 
     
         1 . A thread forming apparatus for use in forming a plurality of threads on a can body having a base and sidewall extending from the base, the thread forming apparatus comprising:
 a punch mechanism including a punch shaft and a cylindrical punch coupled to the punch shaft and having a plurality of circumferentially spaced-apart punch projections, the punch mechanism being structured to be moved radially and rotate continuously about the rotation axis of the punch mechanism in a first direction;   a die mechanism including a die shaft and a cylindrical die connected to the die shaft and having a plurality of circumferentially spaced-apart die recesses, the die mechanism being structured to be moved radially and rotate continuously about the rotation axis of the die mechanism in a second direction opposite the first direction; and   a number of actuating arrangements connected to the punch shaft and the die shaft and structured to translate the punch mechanism and the die mechanism radially relative to a central axis of the can body and rotate each of the punch mechanism and the die mechanism about respective rotation axes for forming a plurality of threads on the can body.   
     
     
         2 . The thread forming apparatus of  claim 1 , wherein each punch projection comprises a male thread form geometry and comprises a protrusion, a protuberance, or a ledge, and wherein each die recess comprises a female thread form geometry that is a negative of the male thread form geometry. 
     
     
         3 . The thread forming apparatus of  claim 1 , wherein the cylindrical punch is positioned and structured to engage an outer surface of the sidewall of the can body and wherein the cylindrical die is positioned and structured to engage an inner surface of the sidewall of the can body. 
     
     
         4 . The thread forming apparatus of  claim 1 , wherein the cylindrical punch is positioned and structured to engage an inner surface of the sidewall of the can body and wherein the cylindrical die is positioned and structured to engage an outer surface of the sidewall of the can body. 
     
     
         5 . A thread forming apparatus structured to form a plurality of threads on a can body having a base and sidewall extending from the base, the thread forming apparatus comprising:
 a punch mechanism including a punch shaft and a convex shaped punch connected to the punch shaft, the punch mechanism being structured to be moved radially with respect to a longitudinal axis of the can body;   a die mechanism including a die shaft and a die having a concave face coupled to the die shaft, the die mechanism being structured to be moved radially with respect to the longitudinal axis; and   a number of actuator arrangements connected to the punch shaft and the die shaft and structured to move the punch mechanism and the die mechanism radially relative to the longitudinal axis of the can body for forming a plurality of threads on the can body.   
     
     
         6 . The apparatus of  claim 5 , wherein the number of actuating arrangements includes a punch actuator and a die actuator, the punch actuator including a punch cam assembly and a punch cam drive structured to drive the punch cam assembly, the die actuator including a die cam assembly and a die cam drive structured to drive the die cam assembly. 
     
     
         7 . The apparatus of  claim 5 , wherein the actuator is a linkage assembly including a main rod structured to be moved axially along the central axis, branch rods connected to the main rod and structured to be moved axially parallel to the central axis, a plurality of 4-hinge punch linkages connected to the branch rods and the punch shaft and structured to cause the punch shaft to be moved radially toward the can sidewall, the radial movement of the punch shaft causing the convex shaped punch to be pressed into the concave base of the die, and a 4-hinge die linkage connected to the branch rods and the die shaft and structured to cause the die to move radially toward the can sidewall. 
     
     
         8 . The apparatus of  claim 5 , wherein the actuator is a linkage assembly including a main rod structured to move axially along the central axis of the can body, a branch punch rod connected to the main rod and structured to move axially parallel to the central axis, a branch die rod connected to the main rod and structured to move axially along the central axis, a punch linking rod connected to the branch punch rod at a punch sliding connector at a first end and to the punch shaft at a second end, and a die linking rod having a first end and a second end connected to the die shaft, the die linking rod being connected to the branch die rod at a die sliding connector, the punch linking rod and the die linking rod extending parallel to each other and radially outward from the central axis at an angle.