RU1825696C - Process of resistance spot welding - Google Patents

Abstract

Usage: in the spot welding of various products. SUMMARY OF THE INVENTION: The strength of the welding current and the time of its flow are determined on the condition that the mutual divergence of the electrodes before the end of the current pulse is not reduced. The divergence of the electrodes is limited by the force, the value of which is set from the proposed ratio. The initial and final magnitude of the compression force of the electrodes is set on the condition that there are no spikes. 1 ill.

Description

The invention relates to contact spot welding technology and can be used in mechanical engineering.

The aim of the invention is to reduce the complexity of the welding process.

The goal is achieved in that in the method of contact spot welding, in which, during the pulse of the welding current, the compression force of the electrodes is changed from the initial to the final value according to the curve of the force with which the parts to be welded act on the electrodes while limiting their mutual difference due to expansion of the zone metal welding when it is heated, the welding mode by the strength of the welding current and the time of its flow is determined from the condition that the mutual divergence of the electrodes before the end of the welding current pulse is not smart decreases, and its value is limited by the force proportional to the mutual divergence of the electrodes during the formation of the compound, the value of which is set from the relation

FK - FHl

(1)

where Pe is the current value of the compression force of the electrodes during the current pulse;

FH, FK - the initial and final magnitude of the compression force of the electrodes when it changes:

1st - the current value of the mutual divergence of the electrodes during the current pulse:

1e amplitude magnitude of the mutual divergence of the electrodes during the current pulse;

in this case, the initial and final magnitude of the compression force of the electrodes is set from the condition that there are no initial and final surges.

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Ltd

The drawing shows the change in the compression force of the electrodes during a current pulse during welding according to the proposed method.

The following notation is accepted here:

FO - compression force of cold parts before the start of a current pulse;

F3t is the current value of the compression force of the electrodes when it changes during a current pulse;

FH is the initial value of the compression force of the electrodes;

FK is the final value of the compression force of the electrodes;

FCB - the compression force of parts driven by a machine;

Fnp — forging force of compression of the electrodes;

Ice - pulse of welding current;

tc is the compression time of cold parts;

ten duration of a pulse of welding current;

tnp is the forging time of the joint;

The resistance spot welding method is carried out in the following sequence of operations.

Initially, as with traditional methods of contact spot welding, the parts to be welded are compressed by the machine drive with the force F0 of compressing cold contacts. Then, during the tcx compression of cold parts, the compression force of the electrodes is reduced from FO to the initial value Γ "of the compression force of the electrodes during the current pulse. C. the instant of the onset of the current pulse 1Sv during tee the mutual divergence of the electrodes 1E limit force F3t. proportional to the mutual divergence of the electrodes, the value of which is set from relation (1). This can be accomplished, for example, by using known devices that limit the mutual divergence of the electrodes by means of elastic elements connected to the electrodes, or that the movable electrode slide in the guide device. In this case, the stiffness ZK of the elastic elements of the mechanical circuit of the machine, limiting the mutual divergence of the electrodes, should provide an increase in F3t from Fl (to FK during tee with an amplitude divergence of electrodes of 1E. From (1) it can be determined as follows

Z, F, -F,

(2)

In this case, the welding mode according to the strength of the welding current and the time of its flow (rigidity of the mode) is determined from the condition that the mutual divergence of the electrodes until the end of the welding current pulse does not decrease. The initial FH and final Pk values of the compression force of the electrodes during the current pulse, as in the known methods, are set according to known methods from

conditions of the absence of initial and final splashes.

The drawing shows the change in the compression force of the electrodes F3t, measured experimentally when welding parts made of steel

12X18H10T with a thickness of 1.5 + 1.5 mm on an MTPU-300 machine with an upgraded mechanical circuit and compliance with the described conditions (, 3 kA, tCB..16 s. KN. KN, kN / mm). The above example shows that, when the conditions of the proposed welding method are met, the change in F3t during tee corresponds to the required parameters and does not require an additional increase in effort at the final stage

process.

Compared with the known, the proposed welding method has a lower complexity, because it is not necessary to manufacture complex drives of programmed force change and maintenance work during operation.

Claims (1)

The claims The method of contact spot welding, in which a pulse of the welding current is supplied, the compression force of the electrodes is changed from the initial to the final value depending on the change in the force with which Weldable parts on the electrodes. ensuring their mutual divergence, and increase the compression force of the electrodes to the forging after the end of the welding current pulse, characterized in that, in order to reduce the complexity of the welding process, the mutual divergence of the electrodes is reduced after the end of the welding current pulse, the current value of the compression force of the electrodes during welding current pulse is determined from the expression re, -, pH + P (lst. At the end of the current pulse, the forging force Ff, p is applied by the machine drive. where F3t is the current value of the compression force of the electrodes during the current pulse; FH, FK - the initial and final magnitude of the compression force of the electrodes: I3i is the current value of the mutual divergence of the electrodes during the current pulse ;. e the amplitude value of the mutual divergence of the electrodes in  No. 0.12 0.16 s m current pulse and the initial and final magnitudes of the compression forces of the electrodes are determined from the condition that there are no spikes. 0.20 te tnf