Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
METHOD OF LASER CUTTING AND APPLYING AN ANTI-CORROSION COATING TO THE CUTTING SURFACE
Document Type and Number:
WIPO Patent Application WO/2001/036149
Kind Code:
A1
Abstract:
A process for treating an exposed edge of a formed hole in a metal substrate, includes the steps of: delivering a noble metal to a region of the exposed edge to be treated; and applying a radiation beam from a laser in the region to bond the noble metal to the exposed edge.

Inventors:
Hill, Ross (170 Waller Street Whitby, Ontario L1R 2R4, CA)
Barton, George (13499 Laneden West Holly, MI, 48442, US)
Application Number:
PCT/CA2000/001340
Publication Date:
May 25, 2001
Filing Date:
November 10, 2000
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
DECOMA INTERNATIONAL INC. (50 Casmir Court Concord, Ontario L4K 4J5, CA)
Hill, Ross (170 Waller Street Whitby, Ontario L1R 2R4, CA)
Barton, George (13499 Laneden West Holly, MI, 48442, US)
International Classes:
B23K35/28; C23C24/10; C23C26/02; (IPC1-7): B23K35/28; B23K26/00; C23C26/02
Foreign References:
GB2086942A1982-05-19
EP0950461A21999-10-20
DE2625466A11977-12-22
DE3808302A11989-09-21
DE714026C1941-11-20
Attorney, Agent or Firm:
Imai, Jeffrey T. (Magna International Inc. 337 Magna Drive Aurora, Ontario L4G 7K1, CA)
Download PDF:
Claims:
We claim:
1. A process for treating an exposed edge of a formed hole in a metal substrate, comprising the steps of : delivering a noble metal to a region of the exposed edge to be treated; and applying a radiation beam from a laser in the region to bond the noble metal to the exposed edge.
2. A process as claimed in claim 1 wherein said metal substrate is a steel and said noble metal is zinc.
3. A process as claimed in claim 2 wherein said zinc is in a powdered form.
4. A process as claimed in claim 3 wherein said zinc is combined with a binder which evaporates during the bonding step.
5. A process as claimed in claim 3 wherein said zinc is electrostatically charged.
6. A process as claimed in claim 2 wherein said zinc is in a solid form.
7. A process as claimed in claim 1 wherein said step of applying a radiation beam, includes moving the radiation beam along the exposed edge and continuously delivering the noble metal.
8. A process as claimed in claim 7 wherein said noble metal is in a powdered form.
9. A process as claimed in claim 8 wherein said noble metal is combined with a binder which evaporates during the bonding step.
10. A process as claimed in claim 9 wherein said noble metal is electrostatically charged.
11. A process as claimed in claim 1 wherein said step of applying a radiation beam simultaneously cuts said formed hole with said exposed edge.
12. A process as claimed in claim 11 wherein said metal substrate is a steel and said noble metal is zinc.
13. A process as claimed in claim 12 wherein said zinc is in a powdered form.
14. A process as claimed in claim 13 wherein said zinc is combined with a binder which evaporates during the bonding step.
15. A process as claimed in claim 13 wherein said zinc is electrostatically charged.
16. A process as claimed in claim 1 wherein said process includes a prestep of providing a metal substrate and forming a hole in the metal substrate, said hole having an exposed edge.
17. A process as claimed in claim 16 wherein said step of applying a radiation beam includes moving the radiation beam along the exposed edge and continuously delivering the noble metal.
18. A process as claimed in claim 17 wherein said noble metal is in a powdered form.
19. A process as claimed in claim 18 wherein said noble metal is combined with a binder which evaporates during the bonding step.
20. A process as claimed in claim 19 wherein said noble metal is electrostatically charged.
Description:
METHOD OF LASER CUTTING AND APPLYING AN ANTI-CORROSION COATING TO THE CUTTING SURFACE Field of Invention This invention relates to a method of laser cutting and applying an anti- corrosion coating to the cutting surface.

Background of Invention Rust and corrosion is a serious problem for vehicles. In order to minimize corrosion, the vehicles are hot dipped in a zinc bath to apply an anti-corrosion coating.

On certain vehicles, trim pieces are applied to the exterior surfaces of the vehicle.

Certain vehicle manufacturers are reluctant to pierce holes in the exterior panels so as to facilitate fasteners for retaining the trim pieces. The pierced holes expose untreated surfaces of the metal panel. The untreated surfaces present a foothold for corrosion, reducing the effectiveness of the anti-corrosion coating.

Summary of the Invention The disadvantages of the prior art may be overcome by providing a process by which zinc, or any noble metal whose purpose is to protect the base material i. e. steel, by acting as a sacrificial anode, is deposited on the edges of a freshly formed hole to provide an anti-corrosion coating equal to or better than the base material.

According to one aspect of the invention, there is provided a method of using heat generated by the laser to bond the zinc to the steel. The method of the present invention may be done during the laser cutting pass or during a second pass around the cut.

According to another aspect of the invention, there is provided a method for coating a raw surface by delivering zinc to the surface by either spraying powdered zinc, delivering zinc in a semi-solid form or delivering zinc in a solid form, and bonding the zinc to the raw or exposed surface by laser heating the zinc.

According to another aspect of the invention, there is provided a process for treating an exposed edge of a formed hole in a metal substrate. The process includes the steps of : delivering a noble metal to a region of the exposed edge to be treated; and applying a radiation beam from a laser in the region to bond the noble metal to the exposed edge.

Description of the Drawings In drawings which illustrate embodiments of the invention, Figure 1 is a side sectional view of a sheet steel being treated by the method of the present invention; Figure 2 is a side sectional view of a sheet steel being treated by a second embodiment of the method of the present invention; and Figure 3 is a side sectional view of a sheet steel being treated by a third embodiment of the method of the present invention.

Detailed Description of the Invention Referring to Figure 1, there is illustrated a laser cutting system 12 and a metal substrate in the form of sheet 14 being treated by the method of the present invention.

The laser cutting system 12 generally comprises a an excimer laser 16 focused through a lens 18 to a target. The operation of the laser 16 and lens 18 is more particularly described in United States Patent no. 4,857,699.

The sheet 14 is preferably a sheet of zinc galvanized steel. Sheet 14 has a hole 20 formed therein. Hole 20 can be formed using any conventional technique, including piercing, lancing, stamping, cutting, and laser cutting. If laser cutting is utilized, the method of the present invention can either be applied post cutting or simultaneously with the laser cutting. As is apparent, the hole forming process will expose edges of untreated metal in sheet 14 about hole 20.

The laser cutting system 12 includes a noble metal delivery system. In the first embodiment, the delivery system comprises a tube 22 connected to a source of

powdered zinc. The tube 22 has a nozzle 24 at the delivery end for producing a desired spray pattern for the powdered zinc 26.

The powdered zinc 26 is preferably electrostatically charged to deliver the powdered zinc 26 to the untreated edges of hole 20. As the powdered zinc is being applied to the edge of hole 20, the laser is activated directing a radiation beam to the region of the powdered zinc 26. The powdered zinc 26 is heated and will bond to the edge of hole 20, thereby forming a coating. The laser cutting system 12 is moved relative to the sheet 14 to treat the entire length of the exposed edge.

As is now apparent to those skilled in the art, the sheet 14 can be any type and grade of metal, steel and alloys and the noble metal can be selected based on the sheet 14. Additionally, it is now readily apparent to those skilled in the art that the process of the present invention can be fully automated.

Referring to Figure 2, there is illustrated a second embodiment of the present invention. In this embodiment, the noble metal delivery system is in the form of delivering a putty or semi-solid zinc 28. The semi-solid or putty zinc is prepared by combining powdered zinc with some type of binder that would evaporate during the heating process. The zinc 28 is squeezed out onto the edge of the hole 20 which is then heated up by the laser 16.

Referring to Fig. 3, there is illustrated a third embodiment of the present invention. In this embodiment, the noble metal delivery system is in the form of applying a solid zinc to the edge of the hole 20 and then heated by the laser 16.

Although the disclosure describes and illustrates the preferred embodiments of the invention, it is understood that the invention is not limited to these particular embodiments. Many variations and modifications will now occur to those skilled in the art.