Jeffrey D Calhoun

US Patent:

47888415, Dec 6, 1988

Filed:

Nov 18, 1987

Appl. No.:

7/122071

Inventors:

Jeffrey D. Calhoun - Lafayette IN
David A. Davis - Lafayette IN

Assignee:

Aluminum Company of America - Pittsburgh PA

International Classification:

B21C 124

US Classification:

72 22

Abstract:

Apparatus and method for providing the wall of an elongated metal tube with a plurality of precisely located thick and thin wall portions lengthwise on the tube. The apparatus includes a drawing die having a relatively wide mouth, and a drawing bulb located in the tube to be drawn and for entering the die when the tube is pulled through the die. The bulb has a constant cross section and a relatively square nose. An actuator is provided for inserting the nose of the bulb into the mouth of the die to provide each thin wall portion and for withdrawing the nose from the die to provide each thick wall portion while drawing the tube. An electrical controller controls the actuator, and a distance measuring device outputs signals to the controller that are representative of precise increments of tube travel. The controller, in response to the signals, is effective to precisely control the occurrences of bulb insertion and withdrawal. The speed and accuracy of the apparatus make the step wall tube products cost competitive with traditional straight wall products while saving weight and raw material.