Welder with indirect sensing of weld fastener position
An upper electrode assembly for welding fasteners includes a body that supports an electrode that has an aperture. The aperture is configured to receive a movable pin of a lower electrode assembly arranged opposite the upper electrode assembly. The lower electrode assembly supports a fastener in a welding position. The upper electrode assembly includes a position sensor which includes a position sensor member that is arranged in the body and is configured to cooperate with the pin to detect a fastener welding characteristic.
1. An electrode assembly for welding fasteners, wherein the electrode assembly includes a body supporting an electrode having an aperture, the aperture is configured to receive a movable pin of another electrode assembly arranged opposite the electrode assembly, the other electrode assembly supports a fastener in a welding position, the electrode assembly comprising:
a position sensor including a position sensor member arranged in the body and configured to cooperate with the pin to detect a fastener welding characteristic.
2. The electrode assembly according to claim 1 , wherein the position sensor has a linear variable displacement transducer (LVDT).
3. The electrode assembly according to claim 2 , wherein the body includes a bore, and the position sensor includes a piston slidably received in the bore, the LVDT having a LVDT core secured to one side of the piston.
4. The electrode assembly according to claim 3 , wherein the position sensor member includes a probe slidably received in the aperture and secured to another side of the piston opposite the LVDT.
5. The electrode assembly according to claim 4 , wherein the probe includes a removable tip on a side opposite the piston, the tip configured to engage the pin.
6. The electrode assembly according to claim 3 , comprising an air port provided in the body and in fluid communication with an air source and the piston.
7. The electrode assembly according to claim 1 , comprising a water jacket surrounding at least a portion of the body and in fluid communication with a fluid cooling source.
8. A weld gun assembly including first and second electrode assemblies, the first electrode configured to support a workpiece to which a fastener is welded, the weld gun assembly comprising:
the first electrode assembly includes a movable pin configured to support the fastener in a welding position; and
a second electrode assembly includes a body supporting an electrode having an aperture, the aperture is configured to receive the movable pin, the second electrode assembly has a position sensor member arranged in the body and configured to cooperate with the pin to detect a fastener welding characteristic.
9. The weld gun assembly according to claim 8 , wherein the first electrode assembly includes a lower electrode having a surface configured to support the workpiece, with the pin protruding through the workpiece.
10. The weld gun assembly according to claim 9 , wherein the pin is movable between multiple positions corresponding to the fastener welding characteristic, the position sensor member moving with the pin.
11. The weld gun assembly according to claim 8 , wherein a position sensor includes the position sensor member, the position sensor has a linear variable displacement transducer (LVDT).
12. The weld gun assembly according to claim 11 , wherein the body includes a bore, and the position sensor includes a piston slidably received in the bore, the LVDT having an LVDT core secured to one side of the piston.
13. The weld gun assembly according to claim 12 , wherein the position sensor member includes a probe slidably received in the aperture and secured to another side of the piston opposite the LVDT.
14. The weld gun assembly according to claim 13 , wherein the probe includes a removable tip on a side opposite the piston, the tip configured to engage the pin.
15. The weld gun assembly according to claim 12 , comprising an air port provided in the body and in fluid communication with an air source and the piston.
16. The weld gun assembly according to claim 8 , comprising a water jacket surrounding at least a portion of the body and in fluid communication with a fluid cooling source.
17. The weld gun assembly according to claim 8 , including a position sensor that includes a position sensor member, the position sensor includes a position sensing element in communication with the position sensor member, the position sensing element arranged outside the body.
18. A method of detecting a fastener welding characteristic during welding, the method comprising the steps of:
supporting a fastener with a movable pin at one electrode assembly;
clamping the fastener to a workpiece with the one electrode assembly and another electrode assembly, wherein a position sensor member is carried by the other electrode assembly; and
engaging the movable pin with the position sensor member during the clamping step to detect a fastener welding characteristic.
19. The method according to claim 18 , wherein the clamping step includes receiving the movable pin within an electrode of the other electrode assembly.
20. The method according to claim 18 , wherein a position sensor includes the position sensor member and has a linear variable displacement transducer (LVDT), and the engaging step includes axially displacing the LVDT.
21. The method according to claim 20 , wherein the position sensor member includes a probe operatively secured to the LVDT, and the engaging step includes the probe engaging the movable pin.