Electrode protection device, spot-welding tool and resistance welding method

• US 20050230362A1
• Filed: 05/26/2003
• Published: 10/20/2005
• Est. Priority Date: 07/03/2002
• Status: Active Grant

• Current Assignee: Fronius International GmbH (G&K Privatstiftung)
• Original Assignee: Fronius International GmbH (G&K Privatstiftung)
• Inventors: Stieglbauer, Walter, Himmelbauer, Karin, Wimmer, Manfred
• Granted Patent: US 7,473,865 B2
• Time in Patent Office: Days
• US Class Current: 219/119
• CPC Class Codes: B23K 11/11 Spot welding
• CPC Class Codes: B23K 11/3009 Pressure electrodes
• CPC Class Codes: B23K 11/309 Wire electrodes
• CPC Class Codes: B23K 11/314 Spot welding guns, e.g. mounted on robots
• CPC Class Codes: B23K 11/36 Auxiliary equipment B23K11/31 takes precedence
• CPC Class Codes: B23K 2101/18 Sheet panels

Abstract

The invention relates to a device for protecting an electrode (4) during the resistance welding of workpieces, particularly of metal sheets (6, 7), comprising a strip (1) that is placed over the electrode (4), preferably in a manner that enables it to be displaced in relation thereto. In order to reduce the wearing of the electrode (4), the invention provides that the strip (1) consists of at least two metal strips (2, 3), which are arranged one atop the other and which are made of different materials. The materials of the metal strips (2, 3) are preferably matched to the material of the electrode (4) and to the material of the workpiece, particularly the metal sheet (6, 7), with regard to predetermined properties. The invention also relates to a spot-welding tool (8) for carrying out the resistance welding of workpieces, particularly of metal sheets (6, 7), comprising at least one electrode (4), and to a resistance welding method during which two workpieces, particularly metal sheets (6, 7), are welded to one another by spot-welding tools (8).

Claims

1. A device for the protection of an electrode (4) during the resistance welding of workpieces, particularly metal sheets (6, 7), including a strip (1) placed over the electrode (4), preferably in a manner displaceable relative to the same, wherein the strip (1) is comprised of at least two superimposed metal strips (2, 3) made of different materials, said metal strips (2, 3) of the electrode protection strip being exclusively positively connected.

2. A protection device according to claim 1, wherein the material of the metal strip (2) facing the electrode (4) exhibits little tendency to adhering to the material of the electrode (4), and the material of the metal strip (3) facing the workpiece, particularly metal sheet (6, 7), exhibits little tendency to adhering to the material of the workpiece.

3. A protection device according to claim 1, wherein the material of the metal strip (2) facing the electrode (4) is selected from the group of ferrous metals, or an alloy having its main component selected from the group of ferrous metals, and the material of the metal strip (3) facing the workpiece to be welded, particularly metal sheet (6, 7), is made of copper or a copper alloy.

4. A protection device according to claim 1, wherein the material of the metal strip (2, 3) and, in particular, of the metal strip (2) facing the electrode (4) has a melting temperature of above 1000°

C. and/or a conductivity of above 1 m/(Ω

*mm²).

6. A protection device according to claim 1, wherein the metal strips (2, 3) are connected by rabbeting, gluing, stamping or welding.

7. A protection device according to claim 1, wherein the metal strips (2, 3) are superimposed in a congruent manner.

8. A protection device according to claim 1, wherein the metal strips (2, 3) are arranged so as to be displaceable relative to each other.

9. A protection device according to claim 8, wherein the metal strips (2, 3) are arranged so as to be displaceable at different speeds.

5. (cancelled)

10. A spot-welding tool for the resistance-welding of work-pieces, particularly metal sheets (6, 7), including at least one electrode (4), wherein a pressure element (9) for holding down the workpieces, particularly metal sheets (6, 7), is arranged on the electrode (4) in the region of the electrode cap (5) to prevent, in particular, process-dependent warping or arching of the workpieces, particularly metal sheets (6, 7).

12. A spot-welding tool according to claim 10, wherein the pressure element (9) projects beyond the electrode in the state of relief.

13. A spot-welding tool according to claim 10, wherein means for the application of force on the pressure element (9) are provided such that the pressure element (9) exerts a pressure or force on the workpieces, particularly metal sheets (6, 7), during operation.

14. A spot-welding tool according to claim 13, wherein said means for the application of force is comprised of an elastic element and, for instance, a spring or an adjustment means (15).

15. A spot-welding tool according to claim 13, wherein the means for the adjustment of the force exerted on the pressure element (9) are provided.

16. A spot-welding tool according to claim 10, wherein a supporting element (13) is arranged on the electrode (4), which supporting element preferably includes guide channels (14) for the reception of the strip (1).

17. A spot-welding tool according to claim 10, wherein the guide (10) for the strip (1) within the pressure element (9) is configured such that the strip (1) projects beyond an end face (12) of the pressure element (9).

18. A spot-welding tool according to claim 10, wherein the pressure element (9) is designed in the form of a metal ring having a lower electric conductivity than the electrode (4).

19. A spot-welding tool according to claim 10, wherein the pressure element (9) is designed as a sensor for the detection of the contact of the spot-welding tool (8) with the workpieces, particular metal sheet (6, 7).

11. A spot-welding tool for the resistance-welding of workpieces, particularly metal sheets (6, 7), including at least one electrode (4) and a winding mechanism for winding and unwinding a strip (1) for the protection of said at least one electrode (4), wherein a pressure element (9) is arranged on the electrode (4) in the region of the electrode cap (5), which pressure element (9) includes a guide (10) for the strip (1) and is connected with the electrode (4) in a manner movable in the longitudinal direction thereof so as place the strip in a spaced-apart relationship to the electrode (4).

20. A resistance-welding method by which two workpieces, particularly metal sheets, are welded with each other using spot-welding tools, wherein at least two electrodes are pressed against each other and powered with energy with the workpieces, particularly metal sheets, being interposed, wherein the contact of the spot-welding tool with the workpiece is detected by an element, particularly pressure element, movably arranged on an electrode and projecting beyond the electrode and, as such contact is detected, the pressure element is being displaced relative to the electrode until the electrode contacts the workpiece.

21. A method according to claim 20, wherein the detection of the contact of the pressure element, with the workpiece is realized using electric energy to power the pressure element, or the strip for the protection of the electrodes guided within the pressure element.

22. A method according to claim 20, wherein the detection of the contact of the pressure element, with the workpiece is effected mechanically.