Thermal-assisted roll forming of high strength material

Patent metadata

Field	Value
Publication number	US-9783865-B2
Application number	US-201414256045-A
Country	US
Kind code	B2
Filing date	Apr 18, 2014
Priority date	Apr 18, 2014
Publication date	Oct 10, 2017
Grant date	Oct 10, 2017

Abstract

A thermal-assisted method deforms plastically a high-strength material using a high-intensive heat source. The high-strength material may be a cold-rolled sheet aluminum of strength greater than 300 megapascal (MPa) or a cold-rolled sheet steel of strength greater than 1000 MPa. The cold-rolled sheet metal is heated just before bending to a temperature near or above the critical temperature for the material and is followed by rapid quenching after bending.

First claim

What is claimed is:

1. A process, for roll forming high-strength cold-rolled sheet metal in a roll-forming production line having heated rollers and cooling rollers, comprising:
feeding the high-strength cold-rolled sheet metal, having a yield strength of at least 1,500 Megapascals, continuously between rollers on the roll-forming production line;
directing, by conduction heating, intense heat to a focus bending area, of the high-strength cold-rolled sheet metal, subject to present bending in the roll-forming production line, to raise a focus-bending-area temperature to a solutionizing temperature for the high-strength cold-rolled sheet metal, wherein the conduction heating comprises heating at least two pair of adjacent heated rollers, of the rollers of the roll-forming production line, and contacting the high-strength cold-rolled sheet metal with the at least two pair of adjacent heated rollers, so as to raise the focus-bending-area temperature to the solutionizing temperature for the high-strength cold-rolled sheet metal;
bending, at the focus bending area heated, during the conduction heating at the focus bending area, the high-strength cold-rolled sheet metal solutionalized; and
quenching the focus bending area of the high-strength cold-rolled sheet metal rapidly and immediately after bending for the cold-rolled sheet metal, to retain a high-temperature phase structure in the focus area of the high-strength cold-rolled sheet metal at room temperature, wherein the quenching comprises (i) cooling at least two pair of adjacent cooling rollers, of the rollers of the roll-forming production line, closely downstream of the heated rollers in the production line, and (ii) contacting the high-strength cold-rolled sheet metal with the at least two pair of adjacent cooling rollers, so as to, promptly after the bending, quench the focus-bending-area temperature of the high-strength cold-rolled sheet metal.

2. The process of claim 1 , wherein the quenching, using the cooling rollers, causes formation of bainite in the high-strength cold-rolled sheet metal.

3. The process of claim 1 , wherein the quenching, using the cooling rollers, causes formation of retained austenite in the high-strength cold-rolled sheet metal.

4. The process of claim 1 , wherein bending the high-strength cold-rolled sheet metal further comprises bending, using the heating rollers, the high-strength cold-rolled sheet metal to a radius less than three times a thickness of the high-strength cold-rolled sheet metal.

5. The process of claim 1 , wherein bending the high-strength cold-rolled sheet metal further comprises bending, using the heating rollers, the high-strength cold-rolled sheet metal to a radius equaling approximately to a thickness of the high-strength cold-rolled sheet metal.

6. The process of claim 1 , being for roll forming of high-strength cold-rolled sheet metal and for implementing the high-strength cold-rolled sheet metal into an automobile component, further comprising forming the high-strength cold-rolled sheet metal into a bumper or a rocker for an automobile.

7. A process, for roll forming high-strength cold-rolled sheet metal in a roll-forming production line having electric heating rollers and cooling rollers, comprising:
feeding the high-strength cold-rolled sheet metal, having a yield strength of over 1,500 Megapascals, continuously between rollers on the roll-forming production line;
fostering, using the electric heating rollers, intense heat at a focus bending area, of the high-strength cold-rolled sheet metal, subject to present bending in the roll-forming production line, to raise a focus-bending-area temperature to a solutionizing temperature for the high-strength cold-rolled sheet metal, yielding resistance heating, wherein the resistance heating comprises directing electrical current to pass from a first of the electric heating rollers to a second of the electric heating rollers, and so through the focus bending area of the high-strength cold-rolled sheet metal moving between the first electric heating roller and the second electric heating roller, thereby heating the focus bending area to raise the focus-bending-area temperature to the solutionizing temperature for the high-strength cold-rolled sheet metal;
bending, at the focus bending area heated, during the resistance heating at the focus bending area, the high-strength cold-rolled sheet metal solutionalized; and
quenching the focus bending area of the high-strength cold-rolled sheet metal rapidly and immediately after bending for the cold-rolled sheet metal, to retain a high-temperature phase structure in the focus area of the high-strength cold-rolled sheet metal at room temperature, wherein the quenching comprises (i) cooling at least two pair of adjacent cooling rollers, of the rollers of the roll-forming production line, closely downstream of the heating rollers in the production line, and (ii) contacting the high-strength cold-rolled sheet metal with the at least two pair of adjacent cooling rollers, so as to, promptly after the bending, quench the focus-bending-area temperature of the high-strength cold-rolled sheet metal.

8. The process of claim 7 , wherein the quenching, using the cooling rollers, causes formation of bainite in the cold-rolled sheet metal.

9. The process of claim 7 , wherein the quenching, using the cooling rollers, causes formation of retained austenite in the cold-rolled sheet metal.

10. The process of claim 7 , wherein bending, using the heating rollers, the cold-rolled sheet metal further comprises bending the cold-rolled sheet metal to a radius less than three times a thickness of the cold-rolled sheet metal.

11. The process of claim 7 , wherein bending, using the heating rollers, the cold-rolled sheet metal further comprises bending the cold-rolled sheet metal to a radius equaling approximately to a thickness of the cold-rolled sheet metal.

12. A process, for roll forming high-strength cold-rolled sheet metal in a roll-forming production line having heating rollers, comprising:
feeding the high-strength cold-rolled sheet metal continuously between rollers on the roll-forming production line;
fostering, using the heating rollers, intense heat at a focus bending area, of the high-strength cold-rolled sheet metal, subject to present bending in the roll-forming production line, to raise a focus-bending-area temperature to at least a critical temperature for the high-strength cold-rolled sheet metal;
bending, at the focus bending area heated, during the conduction heating at the focus bending area, the high-strength cold-rolled sheet metal heated; and
quenching the focus bending area of the high-strength cold-rolled sheet metal rapidly and immediately after bending for the cold-rolled sheet metal, to retain a high-temperature phase structure for the focus area of the high-strength cold-rolled sheet metal at room temperature.

13. The process of claim 12 , wherein:
the roll-forming production line comprises cooling rollers; and
the quenching comprises (i) cooling at least two pair of adjacent cooling rollers, of the rollers of the roll-forming production line, closely downstream of the heated rollers in the production line, and (ii) contacting the high-strength cold-rolled sheet metal with the at least two pair of adjacent cooling rollers, so as to, promptly after the bending, quench the focus-bending-area temperature of the high-strength cold-rolled sheet metal.

14. The process of claim 12 , wherein:
the heating rollers are electric heating rollers; and
fostering the intense heat comprises directing electrical current to pass from a first of the heating rollers

Assignees

• Gm Global Tech Operations Llc

Inventors

• Sachdev Anil K
• Carsley John E
• Brown Stuart J
• Conrad Louis J

Classifications

• C22F1/002

  by rapid cooling or quenching; cooling agents used therefor · CPC title

• C21D9/46

  for sheet metals · CPC title

• C21D9/52

  for wires; for strips {; for rods of unlimited length} · CPC title

• C21D1/18

  Hardening (C21D1/02 takes precedence); Quenching with or without subsequent tempering (quenching devices C21D1/62) · CPC title

• B62D29/007

  predominantly of special steel or specially treated steel, e.g. stainless steel or locally surface hardened steel · CPC title