System and method for monitoring electrodes of a welder

• US 6,084,195 A
• Filed: 10/24/1997
• Issued: 07/04/2000
• Est. Priority Date: 10/24/1997
• Status: Expired due to Fees

• Current Assignee: CSI Technology Incorporated (Emerson Electric Company)
• Original Assignee: CSI Technology Incorporated (Emerson Electric Company)
• Inventors: Seel, Vaughan, Swaggerty, Gregory
• Primary Examiner(s): Ryan, Patrick
• Assistant Examiner(s): DEY, ANJAN K
• Application Number:
  US08/957,195
• Time in Patent Office: 984 Days
• Field of Search: 219/109, 219/110, 219/86.41, 219/86.33
• US Class Current: 219/86.41
• CPC Class Codes: B23K 11/252 using digital means
• CPC Class Codes: B23K 11/255 the measured parameter being a force B23K11/253 takes precedence
• CPC Class Codes: B23K 11/3018 Cooled pressure electrodes
• CPC Class Codes: B23K 11/3063 Electrode maintenance, e.g. cleaning, grinding
• CPC Class Codes: B23K 11/314 Spot welding guns, e.g. mounted on robots

Abstract

A system and method for monitoring compression pressure, temperature, and alignment of first and second electrodes of a robotic welder. An apparatus is provided with hingedly connected, spaced apart top and bottom plates. An aperture is disposed in the top plate for receiving the first electrode therein and an aperture is disposed in the bottom plate for receiving the second electrode therein. Temperature sensors are mounted adjacent to the top and bottom plates for sensing temperature of the electrodes. A load cell is included in the apparatus for sensing pressure between the electrodes as well as a limit switch for indirectly sensing misalignment between the electrodes. A data processing unit is in electrical communication with the temperature sensors, load cell, and limit switch for performing software analysis.

Claims

1. An apparatus for monitoring first and second electrodes of a welder comprising:

connectedly spaced apart top and bottom plates;

an aperture disposed in the top plate for receiving the first electrode therein;

an aperture disposed in the bottom plate for receiving the second electrode therein;

a temperature sensor mounted adjacent to the top plate for sensing temperature of the first electrode;

a temperature sensor mounted adjacent to the bottom plate for sensing temperature of the second electrode; and

a data processing unit in electrical communication with the temperature sensors for monitoring and determining whether the temperature of the first and second electrodes exceeds a threshold value.

2. The apparatus of claim 1 further including a load cell attached to the bottom plate and in axial alignment with the apertures disposed in the top and bottom plates, the load cell being contacted by the first and second electrodes for sensing compression pressure between the first and second electrodes.

3. The apparatus of claim 1 further including a limit switch mounted on the bottom plate, the limit switch being activated when either of the first and second electrodes contacts the top and bottom plates, respectively, thereby denoting misalignment.

4. The apparatus of claim 1 further including a stop member mounted on the bottom plate at a first end and extending through the top plate at a second end, the stop member including a spring coiled around the stop member and disposed between the first and second ends, and whereby the stop member prevents contact of the top plate with the bottom plate.

5. The apparatus of claim 1 wherein the top and bottom plates are spaced apart and hingedly connected.

6. The apparatus of claim 2 wherein the data processing unit is in electrical communication with the load cell for monitoring and determining whether the compression pressure of the first and second electrodes exceeds a corresponding threshold value.

7. The apparatus of claim 3 wherein the data processing unit is in electrical communication with the limit switch for monitoring and determining whether the alignment of the first and second electrodes exceeds a corresponding threshold value.

8. The apparatus of claim 1 further including a peak and hold circuit in electrical communication with the data processing unit and the temperature sensors for storing peak voltage of the temperature sensors.

9. A system for monitoring compression pressure of first and second electrodes of a welder, the system comprising:

an apparatus comprising;

connectedly spaced apart top and bottom plates,

an aperture disposed in the top plate for receiving the first electrode therein,

an aperture disposed in the bottom plate for receiving the second electrode therein, and

a load cell attached to the bottom plate and in axial alignment with the apertures disposed in the top and bottom plates, the load cell being contacted by the first and second electrodes for sensing compression pressure between the first and second electrodes; and

a data processing unit in electrical communication with the load cell for monitoring and determining whether the compression pressure of the first and second electrodes exceeds a threshold value.

10. The system of claim 9 wherein the apparatus further includes a temperature sensor mounted adjacent to the top plate for sensing temperature of the first electrode, and a temperature sensor mounted adjacent to the bottom plate for sensing temperature of the second electrode.

11. The system of claim 9 wherein the apparatus further includes a limit switch mounted on the bottom plate, the limit switch being activated when either of the first and second electrodes contacts the top and bottom plates, respectively, thereby denoting misalignment.

12. The system of claim 9 wherein the apparatus further includes a stop member mounted on the bottom plate at a first end and extending through the top plate at a second end, the stop member including a spring coiled around the stop member and disposed between the first and second ends, and whereby the stop member prevents contact of the top plate with the load cell.

13. The system of claim 9 wherein the top and bottom plates are spaced apart and hingedly connected.

14. The system of claim 10 wherein the data processing unit is in electrical communication with the temperature sensors for monitoring and determining whether the temperature of the first and second electrodes exceeds a threshold value.

15. The system of claim 11 wherein the data processing unit is in electrical communication with the limit switch for monitoring and determining whether the alignment of the first and second electrodes exceeds a threshold value.

16. The system of claim 9 further including a peak and hold circuit in electrical communication with the data processing unit and the load cell for storing peak voltage of the load cell.

17. A system for monitoring alignment of first and second electrodes of a welder, the system comprising:

an apparatus comprising;

connectedly spaced apart top and bottom plates,

an aperture disposed in the top plate for receiving the first electrode therein,

an aperture disposed in the bottom plate for receiving the second electrode therein, and

a limit switch mounted on the bottom plate, the limit switch being activated when either of the first and second electrodes contacts the top and bottom plates, respectively, thereby denoting misalignment; and

a data processing unit in electrical communication with the limit switch for monitoring and determining whether alignment of the first and second electrodes exceeds a threshold value.

18. The system of claim 17 wherein the apparatus further includes a temperature sensor mounted adjacent to the top plate for sensing temperature of the first electrode, and a temperature sensor mounted adjacent to the bottom plate for sensing temperature of the second electrode.

19. The system of claim 17 wherein the apparatus further includes a load cell attached to the bottom plate and in axial alignment with the apertures disposed in the top and bottom plates, the load cell being contacted by the first and second electrodes for sensing compression pressure between the first and second electrodes.

20. The system of claim 17 wherein the apparatus further includes a stop member mounted on the bottom plate at a first end and extending through the top plate at a second end, the stop member including a spring coiled around the stop member and disposed between the first and second ends, and whereby the stop member prevents contact of the top plate with the load cell.

21. The system of claim 17 wherein the top and bottom plates are hingedly connected.

22. The system of claim 18 wherein the data processing unit is in electrical communication with the temperature sensors for monitoring and determining whether the temperature of the first and second electrodes exceeds a threshold value.

23. The system of claim 19 wherein the data processing unit is in electrical communication with the load cell for monitoring and determining whether the compression pressure of the first and second electrodes exceeds a threshold value.

24. The system of claim 17 further including a peak and hold circuit in electrical communication with the data processing unit and the limit switch for storing peak voltage of the limit switch.

25. A method for monitoring temperature, compression pressure, and alignment of first and second electrodes of a welder, the method comprising the steps of:

determining whether the first and second electrodes are in alignment and, if not, indicating misalignment;

compressing a load cell between the first and second electrodes to produce a load cell signal;

comparing the load cell signal to criteria and determining whether the compression pressure of the first and second electrodes is within a set range;

indicating an anomaly of the compression pressure between the first and second electrodes if the compression pressure is not within the set range;

determining temperature of the first and second electrodes; and

indicating insufficient cooling of the first and second electrodes if temperature of the first and second electrodes is greater than a threshold temperature.

26. The method of claim 25 wherein the threshold temperature is 100°

F.