Electric heating – Metal heating – For bonding with pressure
Reexamination Certificate
1999-01-26
2001-02-06
Evans, Geoffrey S. (Department: 1725)
Electric heating
Metal heating
For bonding with pressure
C073S037500
Reexamination Certificate
active
06184487
ABSTRACT:
BRIEF SUMMARY OF THE INVENTION
This invention relates to systems for inspecting resistance welding electrodes and, more particularly, to an improved inspection system for verifying that resistance welding electrodes have been properly dressed by an electrode tip dresser; that associated electrodes when installed in a weld gun are aligned with each other within predetermined tolerances; and that the weld pressure provided by the weld gun is within predetermined tolerances.
As is well known in the art, during resistance welding processes the tips of the electrodes tend to mushroom (flatten) due to the pressures applied by the associated weld gun and the heat generated by the electrical current that passes through the electrode tips. Also, for example, in the case of welding galvanized steel, a build-up of the brass alloy will form on the surface of the electrode tips. Both of such conditions are causes of poor welds being produced. Consequently, the electrode tips must be dressed periodically to insure that the tip configuration is maintained within predetermined tolerances. As is also well known in the art, in automated welding systems the use of automatic electrode tip dressers has been developed. Although the automated tip dressers are reliable there are cases in which the electrode tips are not properly dressed or are not dressed at all, because of broken or dull dresser cutter blades or other factors.
It is also well known in the art of resistance welding that correct alignment of the electrode tips is essential for good tip life and quality of weld. Loss of alignment may indicate that some part of the weld gun or head is not tightly secured or the electrode shank may have become bent in operation. Electrode pressure applied by the weld tips to the workpiece is also very important in producing successful welds. If the weld pressure is not maintained within predetermined parameters and the pressure is greater than required to produce a good weld, a shortened tip life may result. On the other hand, if the pressure is less than required the weld electrodes may not bring the two sheets of workpiece material together so that a proper weld may be made. Electrode tips that are not properly dressed or that are not properly aligned or if the weld pressure is not correct can result in welds of poor quality, and in some cases no welds whatsoever are produced. Consequently, the resulting substandard parts can have various types of negative consequences, such as requiring the reworking of parts, added costs, necessity of parts sorting, possible liability issues, poor customer relations and other adverse consequences.
An object of the present invention is to overcome the aforementioned problems which can be created when the tips of resistance welding electrodes are not properly dressed or are not properly aligned or when an improper weld pressure is applied to the associated workpieces, and to provide an improved inspection system for verifying that resistance welding electrode tips have been properly dressed, properly aligned, and that proper weld pressure has been applied to the workpieces thereby reducing the risks involved in the spot welding of metal components, and also reducing the problems that can be caused by welding with electrodes having tips that are not properly dressed, or are not properly aligned, or without proper weld pressure being applied to the workpieces.
Another object of the present invention is to provide an improved inspection system incorporating novel low pressure air sensing means for evaluating welding electrode tip faces, physical shape and condition, and the relationship of such tips to predetermined criteria.
Another object of the present invention is to provide an improved inspection system incorporating low pressure air sensing means capable of simultaneously sensing two opposing electrode tips to evaluate the suitability thereof for continuing welding operations satisfying predetermined standards.
Another object of the present invention is to provide an improved inspection system embodying low pressure air sensing means incorporating interchangeable collets permitting the inspection of welding electrodes of various sizes and shapes merely by interchanging the collets.
Another object of the present invention is to provide an improved inspection system that permits two welding electrodes of different sizes and shapes to be inspected at the same time.
A further object of the present invention is to provide an improved inspection system for verifying that the tips of welding electrodes have been properly dressed, and which system is capable of being mounted in close proximity to an electrode tip dresser machine and/or a welding gun.
Another object of the present invention is to provide an improved inspection system for verifying that the tips of welding electrodes are in correct alignment with each other within predetermined criteria.
A further object of the present invention is to provide an improved inspection system for verifying that the pressure applied to the workpieces by the electrodes is correct in accordance with predetermined requirements.
Another object of the present invention is to provide an improved inspection system that will verify weld tip geometry, weld tip alignment and weld tip pressure all simultaneously.
A further object of the present invention is provide an improved inspection system that will provide an output signal to a machine controller respecting whether the electrode tips meet predetermined requirements concerning tip alignment, tip geometry and weld pressure.
Yet another object of the present invention is provide an improved inspection system that is relatively easy to manufacture and assemble at economical cost while providing long life and reliable operation.
The above as well as other objects and advantages of the present invention will become apparent from the following description, the appended claims and the accompanying drawings.
REFERENCES:
patent: 4447697 (1984-05-01), Dunne et al.
patent: 5814720 (1998-09-01), Visscher
patent: 6026838 (2000-02-01), Nicewonger et al.
patent: 9-61108 (1997-03-01), None
patent: 94/09939 (1994-05-01), None
Evans Geoffrey S.
McKinnon Malcolm R.
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