RESISTANCE SPOT WELDING PROCESS CONTROL METHOD Russian patent published in 2007 - IPC B23K11/24 

FIELD: welding processes and equipment, namely apparatuses for controlling process of resistance spot welding.

SUBSTANCE: method comprises steps of measuring at each period in secondary circuit acting values of electric current and voltage drop between electrodes; calculating power factor cos φ and heat quantity liberated for period; controlling ignition angle of thyristors. Voltage drop on electrodes is measured at maximum value of welding electric current. Heat quantity liberated for period is calculated while taking into account measurement results by means of expression: Q_i = I² _act(U_el/I_max)t, where Q_i - heat quantity liberated between electrodes in i-period of welding current, J; I_act - measured for period acting value of welding current, A; I_max - maximum value of welding current for period, A; U_el - voltage drop between electrodes measured at moment of maximum welding current, V; t - time duration of welding current period, s. Calculated heat quality is compared with predetermined one and according to comparison result in next period ignition angle of thyristors is changed while satisfying condition: (I_{act(α i+1})/I_{n (cosφ)}} = (I_act/I_n(cosφ)) x (Q_set/Q_i)^0,5 where Q_set -preset heat quantity liberated for period, J; I_{act(α i+1)} - calculated for given apparatus acting value of welding current for next period depending upon set ignition angle of thyristors α_i+1 and power factor cosφ, A; I_n(cosφ) - acting value of full-phase current depending upon power factor cosφ, A.

EFFECT: enhanced quality stability of spot-welded joints due to elimination or weakening of disturbances.

2 dwg, 1 ex