MEASURING METHOD OF WELDING CONTACT RESISTANCE Russian patent published in 2011 - IPC B23K11/24 

FIELD: measurement equipment.

SUBSTANCE: method can be used to control the operation of resistance spot welding machines and their automatic control. Supply mains voltage U_c and transformation coefficient K_m is determined prior to energising. Actual current value I₂ and duration λ of current pulse is measured at known angle α of opening of thyristors in modes of short circuit and welding. Active resistances of secondary circuit r_2k and r₂ are calculated in short circuit and welding modes as per the specified formula, and resistances of welding contact are determined as difference of resistances r₂ and r_2k. During calculation of resistances the function p(α, λ) is used, which is specified in compliance with empirical formula p(α, λ)=A_λ·λ +A_α·α+A₀, where coefficients A_λ, A_α and A₀ are chosen on the basis of conditions of minimisation of calculation error.

EFFECT: simple hardware and computing devices, low error due to refusal to measure voltage drop on electrodes and compensation of disturbing actions.

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