Dual laser coating apparatus and process

• US 20050266168A1
• Filed: 01/31/2005
• Published: 12/01/2005
• Est. Priority Date: 01/30/2004
• Status: Active Grant

• Current Assignee: Photofusion Technologies Limited
• Original Assignee: Dunfries Investments Ltd.
• Inventors: Poullos, Mark Peter
• Granted Patent: US 7,661,387 B2
• Time in Patent Office: Days
• US Class Current: 427/379
• CPC Class Codes: A47J 27/002 Construction of cooking-vessels; Methods or processes of manufacturing specially adapted for cooking-vessels
• CPC Class Codes: A47J 36/025 Vessels with non-stick features, e.g. coatings
• CPC Class Codes: B05D 2401/32 applied as powders
• CPC Class Codes: B05D 3/0209 Multistage baking
• CPC Class Codes: B05D 3/0254 After-treatment
• CPC Class Codes: B05D 3/06 by exposure to radiation B05D3/02 takes precedence ; plasma treatment B05D3/141
• CPC Class Codes: B05D 5/083 involving the use of fluoropolymers

Abstract

An apparatus for applying and fusing a powder coating to substrates of various composition uses two lasers to accurately heat the coating to the optimum temperature. A second laser has less power and heats a smaller area than the first laser. Temperature control is enhanced by the ability to superheterodyne two lasers at separate frequencies. This allows for better absorption of certain materials being fused by the laser. Another common problem associated with laser processing occurs as the polymer heats up. During the heating process the spectral lines are Doppler broadened and slightly shifted. This can affect the absorption of a laser of a fixed wavelength. With the present invention, the optimum laser frequency can be turned to a more optimum frequency for absorption still with sufficient power for fast efficient thermal processing.

Claims

1. A method for coating a substrate, comprising

applying a coating to a substrate,

heating a first area of said substrate to a first temperature with a first heat source,

heating a small area of said first area with a second heat source to a second temperature greater than said first temperature.

2. The method of claim 1, wherein

said coating is applied to said substrate in a powdered form.

3. The method of claim 2, wherein

said powdered coating is a fluoropolymer.

4. The method of claim 1, wherein

said first heat source and said second heat source are a first and second laser.

5. The method of claim 4, wherein

said lasers are diode pump solid state lasers.

6. The method of claim 1, wherein

said substrate is moved past stationary heat sources.

7. The method of claim 1, wherein

said heat sources move past said substrate.

8. The method of claim 4, wherein said lasers are diode lasers.

9. An apparatus for coating a substrate, comprising

a first heat source heating a first area, to a first temperature,

a second heat source heating a small area of said first area to a second temperature greater than said first temperature.

10. The apparatus of claim 9, wherein

said first heat source is a laser.

11. The apparatus of claim 10, wherein

said laser is a diode pump solid state laser.

12. The apparatus of claim 10, wherein

said laser is a diode laser.

13. The apparatus of claim 9, wherein

said second heat source is a laser.

14. The apparatus of claim 13, wherein

said laser is a diode pump solid state laser.

15. 12. The apparatus of claim 13, wherein

said laser is a diode laser.