Method of ensuring the maintenance of constant quality of spot welds
First Claim
1. A method of improving the reproducibility of the welds produced by an electric spot welding machine, which comprises(a) passing a preheating current of lower magnitude than a subsequent welding current through the workpieces to be welded;
- (b) monitoring the resistance of the weld starting with the first cycle of preheating current;
(c) determining when the rate of decrease of the total weld resistance has fallen below a predetermined limit; and
(d) then switching over from said preheating current to said welding current.
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Accused Products
Abstract
A method of improving the reproducibility of the welds in an electric spot welding machine comprises prior to the initiation of a welding operation passing a preheating current of lower magnitude than the welding current through the parts to be welded. When either the total electrical workpiece resistance of the parts to be welded has fallen below a given limit or when its rate of decrease is slower than a predetermined limit the changeover from preheating current to welding current is effected.
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Citations
8 Claims
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1. A method of improving the reproducibility of the welds produced by an electric spot welding machine, which comprises
(a) passing a preheating current of lower magnitude than a subsequent welding current through the workpieces to be welded; -
(b) monitoring the resistance of the weld starting with the first cycle of preheating current; (c) determining when the rate of decrease of the total weld resistance has fallen below a predetermined limit; and (d) then switching over from said preheating current to said welding current. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of improving the reproducibility of the welds produced by an electric spot welding machine, which comprises
(a) passing a preheating electrical current of lower magnitude than a subsequent welding current through workpieces to be welded at an interface between said workpieces to be welded; -
(b) monitoring the resistance of the weld starting with the first cycle of the preheating current; (c) determining when the total resistance of the interface of said workpieces has fallen below a predetermined limit; and (d) then switching over from said preheating current to said welding current.
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Specification