System and Method of Welding a Workpiece

• US 20130020288A1
• Filed: 07/21/2011
• Published: 01/24/2013
• Est. Priority Date: 07/21/2011
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Hetrick, Elizabeth Therese, Moision, William C.
• Granted Patent: US 10,391,582 B2
• Time in Patent Office: Days
• US Class Current: 219/108
• CPC Class Codes: B23K 11/115 by means of two electrodes placed opposite one another on both sides of the welded parts
• CPC Class Codes: B23K 11/24 Electric supply or control circuits therefor
• CPC Class Codes: B23K 11/25 Monitoring devices

Abstract

A system and method of welding a workpiece. A predetermined current may be applied through electrodes that engage the workpiece. A resistance profile may be generated based on the predetermined current. A weld profile may be selected based on the resistance profile. The weld profile may then be executed to weld the workpiece.

Claims

1. A method of welding a workpiece comprising:

engaging electrodes to the workpiece at a predetermined load force level;

generating a first profile by applying a predetermined current through the electrodes when the predetermined load force level is applied;

selecting a weld profile based on the first profile; and

executing the weld profile to weld the workpiece.

2. The method of claim 1 wherein the electrodes exert a constant force against the workpiece while the first profile is generated.

3. The method of claim 1 wherein executing the weld profile includes applying a weld current that is greater than the predetermined current.

4. The method of claim 1 wherein the step of executing the weld profile includes applying a second load force against the workpiece with the electrodes, wherein the predetermined load force is greater than the second load force.

5. The method of claim 1 further comprising detecting current data, voltage data, electrode position data, and electrode force data during execution of the weld profile.

6. The method of claim 5 further comprising selecting a second profile based on the current data, voltage data, electrode position data, and electrode force data.

7. The method of claim 6 further comprising executing the second profile to forge and heat treat the workpiece.

8. The method of claim 7 wherein executing the second profile further comprises determining whether the workpiece is acceptable and repeating the steps of selecting and executing the second profile when the workpiece is not acceptable.

9. A method of welding a workpiece comprising:

engaging first and second electrodes to opposite sides of the workpiece at a first force level;

applying a fixed current level through the first and second electrodes and generating a first set of attributes including a first resistance slope, a second resistance slope, and a steady state resistance value;

selecting a member of a weld profile set based on the first set of attributes;

executing the selected member of the weld profile set to weld the workpiece;

measuring a second set of attributes that include voltage data, current data, electrode position and electrode force during execution of the weld profile;

selecting a member of a second profile set based on the second set of attributes; and

executing the member of the second profile set to forge and/or heat treat the workpiece.

10. The method of claim 9 wherein the first force level is held constant when the fixed current level is applied.

11. The method of claim 10 wherein no current is applied to the workpiece via the first and second electrodes immediately before and after the fixed current level is applied.

12. The method of claim 9 wherein the fixed current level is less than a maximum current level applied during execution of the selected member of the weld profile set and less than a maximum current applied during execution of the selected member of the second profile set.

13. The method of claim 9 wherein the first force level is greater than a maximum force level applied during execution of the selected member of the weld profile and greater than or equal to a maximum force level applied during execution of the selected member of the second profile set.

14. The method of claim 9 further comprising determining whether the workpiece is acceptable after forging and/or heat treating the workpiece and repeating selection of a member of the second profile set, and executing the selected member of the second profile set when the workpiece is not acceptable.

15. The method of claim 14 wherein a different member of the second profile set is selected when selection of a member of the second profile set is repeated.

16. The method of claim 14 wherein determining whether the workpiece is acceptable is based on a voltage level, a current level, electrode position, and electrode force measured during execution of the member of the second profile set.

17. A system for welding a workpiece comprising:

first and second electrodes;

an actuator that actuates at least one of the first and second electrodes into engagement with the workpiece;

a power supply unit electrically coupled to the first and second electrodes; and

wherein a predetermined fixed current is provided by the power supply unit through the first and second electrodes to generate a ramp up slope, a ramp down slope, and a steady state current, and

wherein a weld profile is executed to weld the workpiece, wherein the weld profile is selected based on at least one of the ramp up slope, ramp down slope and the steady state current.

18. The system of claim 17 wherein the ramp up slope, ramp down slope, and steady state current are generated when the first and second electrodes exert a predetermined constant load force against the workpiece.

19. The system of claim 17 wherein a forge/heat treat profile is selected based on voltage data, current data, electrode position and electrode force obtain during execution of the weld profile.

20. The system of claim 17 wherein the actuator is a servo motor.