Patent ID: 7861571

Claim:
A process that reduces an initial diameter of a tube, comprising the steps of: placing a ball in the tube; inserting an end of the tube into a first circular opening of a die, said die having a second circular opening of a smaller diameter than the first circular opening, and at least one chamber between the first and second circular opening with circular cross sections that decrease in diameter between the first and second circular opening, and wherein the diameters of the cross sections become less than the initial diameter of the tube and the diameter of the ball toward the second circular opening; and moving the tube through said chamber, creating pressure between a wall of the chamber and the ball that reduces the initial diameter of the tube; wherein the ball is not retained in the tube by the use of any object other than the tube and the die; wherein adjacent to the first circular opening in the die there is a first tapered chamber, the diameter of the first tapered chamber becomes less than the initial diameter of the tube; wherein the first tapered chamber is immediately followed by a first cylindrical chamber also having a diameter less than the initial diameter of the tube, thus compressing a wall of the tube as the tube is moved through the die, but neither the first tapered chamber nor the first cylindrical chamber have a diameter less than the diameter of the ball; and wherein the first cylindrical chamber is immediately followed by a second tapered chamber, the diameter of the second tapered chamber becomes less than the diameter of the ball; and trapping the ball at a point where the first cylindrical chamber transitions to the second tapered chamber, and causing the ball to compress the wall of the tube.