Albert F Houchens

US Patent:

44939655, Jan 15, 1985

Filed:

May 25, 1983

Appl. No.:

6/498061

Inventors:

Albert F. Houchens - Rochester MI
Dixon Cleveland - Vienna VA
Basil A. Decina - McLean VA
Dale K. Watney - Troy MI
James R. Havens - Sterling Heights MI
Gregory L. Nagel - Royal Oak MI

Assignee:

General Motors Corporation - Detroit MI

International Classification:

B23K 1100

US Classification:

219109

Abstract:

During a weld period the weld parameters are monitored and data representing the weld resistance curve and the power curve are acquired and stored for analysis by a suitably programmed computer. The derivative of R, R is calculated and stored and the function is divided by power P to obtain R/P. The resistance curve is searched to obtain the maximum value R. sub. m which occurs during the heating phase and the function R/P is searched prior to the time of R. sub. m to find the maximum of that curve representing the highest rate of resistance increase. Then the R/P curve is searched subsequent to its maximum to determine when the function reaches a specified percentage of the maximum. That value occurs at the knee of the resistance curve and approximates the onset of melting in the weld. A prediction of whether a weld is a nugget or a sticker is made by calculating the ratio of weld energy after the onset of melting to the total weld energy, the ratio of the resistance drop after the resistance peak to the peak resistance, and then a weighted sum of the energy ratio and resistance drop ratio.

US Patent:

45033110, Mar 5, 1985

Filed:

May 25, 1983

Appl. No.:

6/498063

Inventors:

Albert F. Houchens - Rochester MI
Basil A. Decina - McLean VA
James R. Havens - Sterling Heights MI
Dixon Cleveland - Vienna VA
Gregory L. Nagel - Royal Oak MI

Assignee:

General Motors Corporation - Detroit MI

International Classification:

B23K 1136

US Classification:

219109

Abstract:

During a weld period the weld parameters are monitored and data representing the weld resistance curve and the power curve are acquired and stored for analysis by a suitably programmed computer. The derivative of R, R is calculated and stored and the function is divided by power P to obtain R/P. The resistance curve is searched to obtain the maximum value R. sub. m which occurs during the heating phase and the function R/P is searched prior to the time of R. sub. m to find the maximum of that curve representing the highest rate of resistance increase. Then the R/P curve is searched subsequent to its maximum to determine when the function reaches a specified percentage of the maximum. That value occurs at the knee of the resistance curve and approximates the onset of melting in the weld. A prediction of whether a weld is a nugget or a sticker is made by calculating the ratio of weld energy after the onset of melting to the total weld energy, the ratio of the resistance drop after the resistance peak to the peak resistance, and then a weighted sum of the energy ratio and resistance drop ratio.