The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 07, 1987
Filed:
Jul. 09, 1986
Gregory L Nagel, Royal Oak, MI (US);
Anthony Lee, West Bloomfield, MI (US);
Warren D Hill, Lake Orion, MI (US);
General Motors Corporation, Detroit, MI (US);
Abstract
A method and apparatus are disclosed for resistance spot welding including applying a preconditioning pulse at the beginning of a welding process to stabilize the resistances at the interface of the sheets being welded and at the interface of the electrodes and the sheets. A current pulse is applied just after contact of electrodes and the workpiece when the electrode force is between about 10% and 75% of its final value to melt interface surfaces followed by a cooling time to permit dissipation of heat from the interfaces, and is finally followed by a conventional weld current schedule. The contact time is determined be electrically monitoring the conductivity between the electrodes as they are moved toward the workpiece. Alternatively, the applied electrode pressure is monitored to determine when sufficient electrode force is applied to the workpiece to achieve the proper resistance for the pulse application.