Resistance spot welding of aluminum to aluminum and steel to steel

Patent metadata

Field	Value
Publication number	US-9676065-B2
Application number	US-201213621299-A
Country	US
Kind code	B2
Filing date	Sep 17, 2012
Priority date	Apr 28, 2010
Publication date	Jun 13, 2017
Grant date	Jun 13, 2017

Abstract

A method for welding a plurality of aluminum to aluminum welds and a plurality of steel to steel welds using the same welder includes providing a resistance spot welder with a pair of weld electrodes having an electrode face radius of curvature in the range between 20 mm and 40 mm. The series of aluminum to aluminum welds is first made, and then, after completing the aluminum to aluminum welds, the series of steel to steel welds are made. After completing the steel to steel welds the weld electrodes are cleaned by an abrasive to remove any buildup or contamination of aluminum on the electrodes. In the event the electrodes have mushroomed, then dressing of the electrodes is provided and then the abrasive cleaning is performed to restore the surface texture.

First claim

The invention claimed is:

1. A method of resistance spot welding aluminum-to-aluminum and steel-to-steel using a single resistance spot welding gun apparatus, the method comprising:
providing a spot welding gun apparatus that carries a pair of opposed electrodes, each of the pair of opposed electrodes having a body and a crowned weld face at one end of the body, the crowned weld face of each electrode having a spherical radius of curvature between 20 mm and 40 mm and further comprising a plurality of concentrically arranged circular ridges that project outwards away from the weld face;
forming a series of aluminum to aluminum welds, wherein formation of each of the aluminum to aluminum welds comprises pressing the opposed electrodes of the spot welding gun apparatus against opposite sides of an assembly of two or more overlapping aluminum panels and exchanging current between the opposed electrodes;
forming a series of steel to steel welds after forming the series of aluminum to aluminum welds, wherein formation of each of the steel to steel welds comprises pressing the opposed electrodes of the spot welding gun apparatus against opposite sides of an assembly of two or more overlapping steel panels and exchanging current between the opposed electrodes; and
dressing each of the electrodes after forming the series of steel to steel welds and before forming another series of aluminum to aluminum welds, wherein, for each of the opposed electrodes, the dressing includes restoring the spherical radius of curvature of the weld face and the plurality of concentrically arranged circular ridges on the weld face, and removing contamination from the weld face that has accumulated as a result of forming the series of aluminum to aluminum welds and the series of steel to steel welds.

2. The method set forth in claim 1 , wherein each of the plurality of concentrically arranged circular ridges on the weld face of each electrode projects outwardly from its associated weld face to a height of between 20 μm and 200 μm, and wherein the circular ridges on each weld face are spaced apart from one another by a distance of 80 μm to 1500 μm.

3. The method set forth in claim 1 , wherein each of the plurality of concentrically arranged circular ridges on the weld face of each electrode has a width ranging from 40 μm to 2000 μm.

4. The method set forth in claim 1 , wherein dressing each of the electrodes comprises engaging the weld face of the electrode with a cutting surface of a cutting blade and rotating the cutting blade around the weld face, the cutting surface of the cutting blade being configured to cut the plurality of concentrically arranged circular ridges into the weld face.

5. The method set forth in claim 1 , further comprising dressing each of the opposed electrodes during formation of the series of aluminum to aluminum welds so as to restore the spherical radius of curvature of the weld face and the plurality of concentrically arranged circular ridges on the weld face and to further remove contamination from the weld face that has accumulated as a result of forming aluminum to aluminum welds.

6. The method set forth in claim 1 , further comprising monitoring each of the electrodes for the occurrence of mushrooming during formation of the series of steel to steel welds.

7. The method set forth in claim 6 , wherein monitoring each of the electrodes for the occurrence of mushrooming comprises determining a length of the electrode and comparing that length to a length determined at an earlier time.

8. The method set forth in claim 1 , wherein each of the opposed electrodes has a yield strength of 400 MPa or greater and an electrical conductivity of greater than 90% IACS.

9. The method set forth in claim 1 , wherein the weld face of each electrode has a diameter (d) in millimeters that satisfies the following equation: d=1.5 mm+4(t) 1/2 , wherein (t) is a thickness of the thinnest aluminum panel included in the assembly of two or more overlapping aluminum panels.

10. The method set forth in claim 9 , wherein the weld face of each electrode has a diameter (d) in millimeters that satisfies the following equation: d=3.0 mm+4(t) 1/2 , wherein (t) is a thickness of the thinnest aluminum panel included in the assembly of two or more overlapping aluminum panels.

11. A method of resistance spot welding aluminum-to-aluminum and steel-to-steel using a single resistance spot welding gun apparatus, the method comprising:
providing a spot welding gun apparatus that carries a pair of opposed electrodes, each of the pair of opposed electrodes having a body and a crowned weld face at one end of the body, the crowned weld face of each electrode having a spherical radius of curvature between 20 mm and 40 mm and further comprising a plurality of concentrically arranged circular ridges that project outwards away from the weld face;
forming a series of aluminum to aluminum welds, wherein formation of each of the aluminum to aluminum welds comprises pressing the opposed electrodes of the spot welding gun apparatus against opposite sides of an assembly of two or more overlapping aluminum panels and exchanging current between the opposed electrodes;
halting formation of the series of aluminum to aluminum welds and removing contamination derived from the aluminum panels from the weld face of each of opposed electrodes, followed by resuming and completing the formation of the series of aluminum to aluminum welds;
forming a series of steel to steel welds after forming the series of aluminum to aluminum welds, wherein formation of each of the steel to steel welds comprises pressing the opposed electrodes of the spot welding gun apparatus against opposite sides of an assembly of two or more overlapping steel panels and exchanging current between the opposed electrodes.

12. The method set forth in claim 11 , further comprising:
dressing each of the electrodes after forming the series of steel to steel welds and before forming another series of aluminum to aluminum welds, wherein, for each of the opposed electrodes, the dressing includes restoring the spherical radius of curvature of the weld face and the plurality of concentrically arranged circular ridges on the weld face, and removing contamination from the weld face that has accumulated as a result of forming the series of aluminum to aluminum welds and the series of steel to steel welds.

13. The method set forth in claim 12 , wherein dressing each of the electrodes comprises engaging the weld face of the electrode with a cutting surface of a cutting blade and rotating the cutting blade around the weld face, the cutting surface of the cutting blade being configured to cut the plurality of concentrically arranged circular ridges into the weld face.

14. The method set forth in claim 11 , wherein halting formation of the series of aluminum to aluminum welds and removing contamination from the weld face of each of opposed electrodes comprises dressing the electrode to restore the spherical radius of curvature of the weld face and the plurality of concentrically arranged circular ridges on the weld face.

15. The method set forth in claim 14 , wherein dressing the electrode comprises engaging the weld face of the electrode with a cutting surface of a cutting blade and rotating the cutting blade around the weld face, the cutting surface of the cutting blade being configured to cut the plurality of concentrically arranged circular ridges into the weld face.

16. The method set forth in claim 11 , wherein each of the opposed electrodes has a yield strength of 400 MPa or greater and an electrical conductivity o

Assignees

• Gm Global Tech Operations Llc

Inventors

• Sigler David R
• Karagoulis Michael J

Classifications

• B23K2103/10

  Aluminium or alloys thereof · CPC title

• B23K2103/04

  Steel {or steel} alloys · CPC title

• B23K11/3063

  Electrode maintenance, e.g. cleaning, grinding · CPC title

• B23K35/302

  Cu as the principal constituent · CPC title

• B23K35/222 Primary

  Non-consumable electrodes · CPC title