SU1505715A1 - Method of checking welding current - Google Patents

Abstract

The invention relates to resistance spot and seam welding and can be used in mechanical engineering in the manufacture of welded structures. The purpose of the invention is to improve the accuracy of control. The method of controlling the welding current is that during the process of making the joint, the effective value of the welding current in each half period is measured. These values are then summarized and the average effective welding current value is determined for the entire duration of the pulse. The specified value is equal to dividing the sum of the effective current values by twice the number of periods. In this case, the average effective current value is determined by the calculation formula. 2 Il.

Description

The invention relates to resistance spot and seam welding and can be used in mechanical engineering in the manufacture of welded structures.

The purpose of the invention is to improve the accuracy of control.

FIG. Figure 1 shows the dependence of the diameter of the casting core and the diameter of the heat-affected zone of the U.v. on the time of welding / s and the shape of the current K. 2 - depends on

The maximum current (final) value of the alternating current / 2cV from the welding time / s and the current form K;

 l

The method consists in the fact that in the process of making the connections, the effective value of the welding current in each half-period is measured, taking into account the actual time of its flow /., These values are summed up

during the current pulse and determine the average effective value of the welding current for the entire time of the pulse duration by dividing the sum of the effective values of the current in each half-period by twice the number of periods constituting the pulse duration of the welding current. The measurement of the average effective value of the welding current is made in accordance with the expression:

ate

about sd

sd

V

/ lv

tt-l-tl (/ - Hf

-

t

where n is the number of periods;

t 2i is the number of half cycles of alternating current; ta - welding time

current;

/). - actual time of welding current flow in a half-period;

 icD - instantaneous value of welding current strength;

T is the time of one period.

The need to control the average effective welding current for all the duration of its pulse is confirmed by experimental data.

When setting up the machine for welding, the current control is made with the "Heating And I measure the A / C and the load characteristic of the machine.

Analysis of the experimental data showed that when welding X18H10T steel on the MT 3201 machine, another 1.5 + 1.5 mm when the mode is established, based on the equality of the final effective values of current at / S1,0,20 s and different form of current, various values of dj are obtained, and ijt.t. Thus, the control of the current in a half-period with the highest current amplitude, corresponding to its end / SI and produced in accordance with the expression L

, lf -dtYdt,

does not give a complete description of the welding process.

It also does not give the full characteristics of the process of monitoring the current when the monitoring is performed in any given period. To obtain the full characteristic of the process during the control of the proposed method, it is necessary to know exactly at what point to control the amount of current. At the control at the moment - when i control is 0.20 s, a smaller value of current corresponds to a smaller value of d and c (rt, and in the case when control t is 0.20 s, larger values of d correspond to a smaller value of current , and d (z.t.v, and this contradicts the physical meaning of the process ..

When monitoring the average current value in the half-period, preceding or following beyond / c / 2, the accuracy is insufficient. In addition, the current control method is not applicable at, 06 s.

To experimentally verify the accuracy of the proposed control method, single-phase AC machine MT 3201 welds plates of steel H18N10T with a thickness of 1.5 + 1.5 mm. The signal from the current sensor is fed to the measuring and computing complex (accumulator) 0 36, which inputs the results of primary data processing to the digital printing device, and the form of the welding current is recorded on a plotter connected to the accumulator 0 36. Next, the received information is entered into a computer, which using the numerical integration method, it calculates the average effective value of the welding current over the duration of its duration. The obtained data is compared with the results of measurement.

five

0

five

0

five

0

five

neither valid, its current values, made by the expression (fi) ivf

/.Vf (

 (n - () T oUt

With the help of the modernized ASU-1M device, on which a time relay is installed to measure the current in a given half-period and to determine the average effective, its current values are measured in the half-period preceded by W / L / 2. The accuracy of the control is estimated as the ratio of the variation of the indications to the average value of all measurements made when setting 10 weld points using the known and proposed methods.

Analysis of the data shows that the implementation of the proposed method of controlling the welding current, when the effective is measured, is its value. welding current in each half-period, taking into account the actual time of its flow (/ ;.), summarize the measured effective values of the current, then the result is divided by twice the number of periods, and the average effective value of the welding current is determined by the duration of its pulse formula

ijic /

-lew /

2 Vi I ,,

tildt

i

m

allows to increase the accuracy of control of welding current.

Claims (1)

Invention Formula The method of control of welding current in contact spot and seam welding single-phase alternating current. In which, in the process of making connections, the actual current value is measured, characterized in that, in order to improve the control accuracy, the effective value of the welding current is measured in each half-period taking into account its actual flow time, the measured effective current values are summed up and the average effective value is determined welding current / dsr for the entire duration of its pulse from the following expression „T / 1 sVl- j 4 dt t where n is the number of periods of alternating current in a pulse of a welding current; - the number of half periods; T is the time of one period; t ;. - actual time of welding current flow in a half-period; K is the start time of the welding current; g St - instantaneous value of the welding current strength. t df, ds.r, e., CMH: i 0.04 0.08 0.12 0.16 0.20 icS CCJ FIG. one IjC8., CK , t 3.5 9.0 8.5 8.0 15 10 tc, rcJ