Method and apparatus for welding current regulation for a resistance welding machine
First Claim
1. A method of regulating a cyclic welding operation in a resistance welding machine which receives alternating input current, and senses welding current and controls the welding time, each welding operation cycle comprising the iterative steps of:
- a. presetting a value of desired welding current is and of desired welding time tr ;
b. determining a value for the desired welding energy, from said values of desired welding current using an integral ∫
i2s dt over said desired welding time tr ;
c. applying welding current;
d. measuring during a time interval (ti) a value of the actual welding current iI, said time interval comprising more than one-half-cycle of the input current;
e. integrating said measured welding current value with previously measured values of welding current according to an integral ∫
i2I dt to determine an actual welding energy value;
f. comparing the actual welding energy value with the desired welding energy value; and
g. switching off the welding current when said actual welding energy value approximately equals said desired welding energy value.
1 Assignment
0 Petitions
Accused Products
Abstract
A method and arrangement are described for regulating the welding operation in a resistance welding machine by sensing the welding current and controlling the welding time. A first integrator (20) determines the desired total energy to be supplied to a welding spot from a desired welding current preset by means of a function generator (18) and a preset welding time. An integrating device (25) connected to the welding-current sensor (14) determines the actual energy supplied. A comparator (24) compares the desired total energy with the actual energy in order to switch off the welding current by means of a start/stop module (30) in the event of equality between desired value and actual value. In this manner, fluctuations in the supply voltage are compensated by lengthening or shortening the time during which energy is supplied to the welding spot in order to ensure the quality of the welding from one welding spot to another.
-
Citations
8 Claims
-
1. A method of regulating a cyclic welding operation in a resistance welding machine which receives alternating input current, and senses welding current and controls the welding time, each welding operation cycle comprising the iterative steps of:
-
a. presetting a value of desired welding current is and of desired welding time tr ; b. determining a value for the desired welding energy, from said values of desired welding current using an integral ∫
i2s dt over said desired welding time tr ;c. applying welding current; d. measuring during a time interval (ti) a value of the actual welding current iI, said time interval comprising more than one-half-cycle of the input current; e. integrating said measured welding current value with previously measured values of welding current according to an integral ∫
i2I dt to determine an actual welding energy value;f. comparing the actual welding energy value with the desired welding energy value; and g. switching off the welding current when said actual welding energy value approximately equals said desired welding energy value. - View Dependent Claims (2, 3, 4)
-
-
5. A regulator for use with a resistance welding machine receiving alternating input current and having a cyclic welding operation, comprising:
-
function generator means for presetting a value of desired welding current (is) and of desired welding time (tr); integrating means for determining a value of the desired total welding energy from said values of desired welding current according to an integral ∫
i2s dt over said desired welding time tr ;means for applying welding current; weld current sensor means for measuring during a time interval (ti) a value of the actual welding current (iI) comprising more than one half cycle of the input current; means for integrating such said measured welding current value with previously measured values fo welding current according to an integral ∫
i2I dt;comparator for comparing the actual welding energy value with the desired welding energy value; and means for switching off the welding current when said actual welding energy value approximately equals the desired welding energy value. - View Dependent Claims (6, 7, 8)
-
Specification