Method of diagnosing degradation of a welding system

• US 7,030,334 B1
• Filed: 03/18/2005
• Issued: 04/18/2006
• Est. Priority Date: 03/18/2005
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Martinez, Juan, Munoz, M. Segrelles, Ortiz, Marivi Alonso, Perez Guerrero, Jose Luis, Ruiz, Daniel
• Primary Examiner(s): Shaw, Clifford C.
• Application Number:
  US10/907,063
• Time in Patent Office: 396 Days
• Field of Search: 219/109, 219/110
• US Class Current: 219/109
• CPC Class Codes: B23K 11/11 Spot welding
• CPC Class Codes: B23K 11/257 the measured parameter being an electrical current
• CPC Class Codes: B23K 11/314 Spot welding guns, e.g. mounted on robots
• CPC Class Codes: B23K 31/125 Weld quality monitoring

Abstract

A method of diagnosing electrical degradation of a welding system. The method includes determining whether a predetermined number of welds has been executed, positioning welding electrodes, applying and measuring current applied through the electrodes, and comparing the measured current to a threshold value.

Claims

1. A method of diagnosing electrical degradation of a welding system, the welding system including a weld gun having a set of electrodes, an actuator for positioning at least one member of the set of electrodes, and a power source, the method comprising:

determining whether a predetermined number of welds has been executed;

positioning at least one member of the set of electrodes a predetermined distance from another member of the set of electrodes if the predetermined number of welds has been executed;

applying current with the power source through the set of electrodes;

measuring the current applied through the set of electrodes;

comparing the current applied through the set of electrodes to a threshold value; and

generating a pass signal if the current applied through the set of electrodes is greater than the threshold value.

2. The method of claim 1 further comprising the step of generating a fail signal if the current applied through the set of electrodes is less than the threshold value.

3. The method of claim 2 wherein the welding system is part of a vehicle body assembly line and the step of generating the fail signal further comprises stopping the vehicle body assembly line.

4. The method of claim 1 wherein the step of comparing the current applied further comprises resetting a counter indicative of a number of welds that has been executed.

5. The method of claim 1 wherein the set of electrodes includes first and second electrodes and the step of positioning the set of electrodes further comprises actuating the first electrode with the actuator to position the first electrode a predetermined distance from the second electrode.

6. The method of claim 1 wherein the set of electrodes includes first and second electrodes and the step of positioning the electrodes further comprises actuating the first and second electrodes to position the first and second electrodes a predetermined distance apart from each other.

7. A method of diagnosing electrical degradation of a welding system, the welding system including a weld gun having a set of electrodes, an actuator for positioning at least one member of the set of electrodes, and a power source, the method comprising:

determining whether a predetermined number of welds has been executed;

positioning at least one member of the set of electrodes proximate another member of the set of electrodes if the predetermined number of welds has been executed;

applying current with the power source through the set of electrodes;

measuring the current applied through the set of electrodes;

comparing the current applied through the set of electrodes to a threshold value; and

generating a pass signal if the current applied through the set of electrodes is greater than the threshold value.

8. The method of claim 7 further comprising the step of generating a fail signal if the current applied through the set of electrodes is less than the threshold value.

9. The method of claim 8 wherein the welding system is part of a vehicle body assembly line and the step of generating the fail signal further comprises stopping the vehicle body assembly line.

10. The method of claim 7 wherein the step of applying current through the set of electrodes further comprises resetting a counter indicative of a number of welds that has been executed.

11. The method of claim 7 wherein the set of electrodes includes first and second electrodes and the step of positioning the set of electrodes further comprises actuating the first electrode with the actuator to position the first electrode proximate the second electrode.

12. The method of claim 11 wherein the first electrode is actuated against the second electrode and held in compression at a constant level of force.

13. The method of claim 7 wherein the set of electrodes includes first and second electrodes and the step of positioning the set of electrodes further comprises actuating the first and second electrodes to position the first and second electrodes proximate each other.

14. The method of claim 13 wherein the first and second electrodes are actuated against each other and held in compression at a constant level of force.

15. A method of diagnosing electrical degradation of a robot-mounted welding system for a vehicle assembly line, the welding system including a weld gun having first and second electrodes, the method comprising:

determining whether a predetermined number of welds has been executed;

positioning the welding gun away from a workpiece with a robot;

positioning the first and second electrodes proximate each other if the predetermined number of welds has been executed;

applying current through the first and second electrodes;

measuring the current applied through the first and second electrodes;

comparing the current applied through the first and second electrodes to a threshold range; and

generating a pass signal if the current applied through the first and second electrodes is within the threshold range.

16. The method of claim 15 further comprising the step of generating a fail signal if the current applied through the first and second electrodes is not within the threshold range.

17. The method of claim 16 wherein the vehicle assembly line includes a controller and the step of generating the fail signal further comprises providing the fail signal to the controller to stop the vehicle assembly line.

18. The method of claim 16 wherein the step of generating the fail signal further comprises powering an indicator.

19. The method of claim 18 wherein the indicator produces a visible signal.

20. The method of claim 18 wherein the indicator produces an audible sound.