Granted Patent B2

US 7,996,978 · App. 11/438,187 · Granted Aug 16, 2011

Abstract

Claims (20)

1. A method for producing a ladder comprising the steps of:

press solution heat treating the extrusion;

quenching the extrusion rapidly enough to retain alloying elements in the extrusion in solution;

stretching the extrusion;

taking the heated and quenched aluminum extrusion and reheating a selected area of the extrusion to at least 550° F. within 10-75 seconds at a rate of 5°-95° F. per second;

requenching the extrusion;

forming the reheated area into a rung within 5 days of quenching; and

attaching the rung directly to a rail without any additional piece.

2. A method as described in claim 1 wherein before the taking step, there is the step of artificially aging with precipitation heat treatment the extrusion.

3. A method as described in claim 2 wherein the reheating step includes the step of reheating the end of the extrusion in an induction coil.

4. A method as described in claim 3 wherein before the taking step, there is the step of casting a log from molten alloyed aluminum.

5. A method as described in claim 4 wherein before the taking step, there is the step of homogenizing the log at a temperature greater than 900° F. for several hours.

6. A method as described in claim 5 wherein before the taking step, there is the step of cutting the log into billets after the log is quenched.

7. A method as described in claim 6 wherein before the taking step, there is the step of preheating and excluding the log into a desired cross-section to form the extrusion.

8. A method as described in claim 7 wherein before the taking step, there is the step of cutting the extrusion to a desired length.

9. A method as described in claim 8 wherein the attaching step includes a step of attaching the rung at the area directly with the ladder rail without any additional piece.

10. A method as described in claim 9 wherein the attaching step includes the step of forming a joint out of the rung with the rail.

11. A method as described in claim 10 wherein the attaching step includes the step of inserting rivets through the rung and the rail to attach the rung to the rail.

12. A method as described in claim 11 wherein the attaching step includes the step of flattening the end of the rung.

13. A method as described in claim 12 wherein the extrusion is a rail and wherein the forming step includes the step of forming the rail into a desired shape.

Assignments (14)