Patent ID: 7004370

Claim:
A device for determining parameters of a welding system using an ultrasonic source ( 14 ) that acts on a welded region ( 18 , 21 , 22 ) with ultrasonic waves, comprising: signal processing means ( 30 ) that in a welding procedure determines a measure for an ultrasonic permeability of the welded region ( 18 , 21 , 22 ) from a received ultrasonic signal (UE), wherein the signal processing means ( 30 ) is adapted for determining a trend characteristic ( 40 ), representing an ultrasonic permeability (D) as a function of a number of welds (n), based on ultrasonic permeability values (Dn 0 , Dn 1 , Dn 2 , Dn 3 ) measured at different welds (n 0 , n 1 , n 2 , n 3 ), and the signal processing means ( 30 ) is further adapted for generating a maintenance signal and/or adjusting a welding current (In 1 , In 2 ) of the welding system based on said trend characteristic ( 40 ).