The present invention relates to a method for testing a welded joint produced by resistance
welding, in which, firstly, in a preparatory phase, the dependence of a
welding quality parameter (8), for example the lens size, on the
welding time in the form of a lens
growth function (16) or an extended lens
growth function (16') is determined from
test data with specified nominal process data (3, 4) of the
welding process, then a self-learning
system (1), for example a neural network, is trained with training data which, on the one hand, contain nominal process data (3, 4) and measured
process measurement data (5, 6, 7, 8) as input data and, on the other hand, welding quality parameters, for example lens sizes, determined by means of the lens
growth function as target data (10).and then, during operation after a
welding process, a welding quality parameter (9, 9'), for example the lens size, is determined by means of the trained self-learning
system on the basis of the specified nominal process data and the recorded
process measurement data.