JPS5823580A - Controlling method for quality of resistance welding - Google Patents

Abstract

PURPOSE:To prevent the variance of the voltage due to the connection position of a detecting lead wire to improve the quality, by monitoring the voltage during resistance welding to detect a peak value and terminating the welding when a voltage drop from the peak value is generated. CONSTITUTION:The voltage between welding electrodes is monitored during resistance welding, and a peak value of the monitored voltage is detected and is compared with a voltage signal; and when the voltage drop of the voltage signal; and when the voltage drop of the voltage signal reaches a preliminarily set value, a welding controller is controlled by the output signal of a comparing circuit to stop or reduce the welding current.

Description

[Detailed description of the invention] This invention relates to a method for controlling the quality of resistance welding.

Conventionally, as a method of controlling the quality of resistor II contact, #
'I monitor the voltage between the welding electrodes during resistance, detect and hold this voltage threshold voltage O peak voltage, and the subsequent drop in the voltage between the electrodes is maintained so that the ratio with the peak voltage is at least A method of controlling the IIk anti-stoIM1 quality by decreasing the proportion of 2- or more and not exceeding 20% and ending the third contact has been proposed.
#HA Japanese Public Notice No. 60317).

In this method of controlling the quality of the resistance flI performance, ** is set to 2 when finished based on the peak value of the voltage between the electrodes and the 0 ratio. Therefore, in this conventional method, the peak voltage detected varies depending on the position where the voltage between the electrodes is detected.
Therefore, there is a drawback that the standard ratio for completing 5iIts fluctuates, and this drawback is caused by complex edicts in the case of resistance S* robots in the automobile industry, etc. Since the lead 4I for detecting the inter-electrode voltage cannot always be connected to the electrode, there is a drawback that the 7OSM quality control device must be adjusted depending on the connection position of the lead.

Therefore, the present invention proposes a method for controlling the quality of the resistance S* so that the measurement results do not differ depending on the connection position of the interelectrode voltage O detection lead wire.
I & serve Jin and t-m.

Embodiments of the invention will be described based on the drawings. First of all, let's talk about the resistance welding quality control fI & placement used in the practical example, based on Houki 11g1. 20 is the 11g1 trowel, 24 is the articulating transformer, 21.22 is the #Autotsuns. 25°26 is the secondary lead wire of the mlI transformer, 27 is the current transformer that detects the current of the secondary lead wire of the casting transformer, and 3.4 is the resistor sin\. 2 is the object to be detected, 31 is a constant current #1 circuit for detecting with a current transformer and removing fluctuations in the 9#llI current, ζO constant current R11l path 31 is detected by a current transformer 27 The response speed changes the current fluctuation to a constant current within the cow cycle. 23 is #1m! ) Tirisk is disposed on the primary lead stitch 22 of the lance and is driven by the constant current circuit 31 to control the current at a constant level; 32. 38 is a lead wire for detecting the voltage between the electrodes; 34 is a human power** circuit, and 85 is a lead @a2. that detects the voltage between the electrodes. 1 circuit for removing the induced electromotive force due to the welding current generated at aa, 36 is an absolute value circuit using the aftereffect current, 37.38 is a sample hold circuit, sample hold circuits 37, 38a constant current IL circuit 3
Sample signals 14]211Il are alternately applied every half cycle from 1 immediately after the cow cycle energization.

39, the sample signal is alternately sampled and held - path 87
．． 88, a switching circuit 40 is a sample and hold circuit 37.
A comparison circuit that outputs a voltage signal as an output signal, 41a a peak value hold circuit that stores the maximum value of the voltage signal, 42 compares the peak value of the voltage signal with the detected nine voltage signals, and compares the peak value with the subsequent voltage signal. 44 is a variable resistor for previously setting the amount of voltage drop Δvt which terminates the resistor iI; 48 is a variable resistor that is set with nine set voltages; A comparison circuit that compares the voltage drop ΔV. When the comparison circuit 43 determines that the voltage drop amount V of voltage No. 11 is suitable to a preset value, the output signal of the ratio I2 circuit 48 is used to determine the # contact control device 20t- Controlled to stop or reduce the welding current.

Next, Figure 162 shows resistance #ll horizontal machine main body 2 mineral covered loose body, 3.
4 holds the aSS body #ll! IIE Tokai, 5,6 Hiro#
A ram for holding a slowing current, 7 a cylinder for shaking the upper ram up and down, 8, 9 a cylinder for 2 mm Vc melting wax flow [--
Shows part I.

Next, referring to the waveform of the threshold voltage shown in the ms diagram, Fig. 3 shows the positions 3a and 4 of the welding electrodes 3 and 4 in Fig. 2.
The voltage between the electrodes was detected between a and the maximum voltage value was 2.
8. The voltage between the electrodes just before the tin 2 s, f occurs is 2.
Al at 2V, voltage drop amount is O, SV, voltage drop ratio Hiro 21- is 6 to 9.

945.6011 Rube 6m in the 3rd #ABFijlH map,
The voltage between the electrodes is detected between @a and the maximum voltage value is &
6V, the voltage between the electrodes just before splash zf occurs is 2.
9V, the amount of voltage drop was 0.7V, and the ratio of voltage drop was 19-.

Diagram 8C is the bond of the piece 8.9 shown in Figure 2.
, the inter-electrode voltage was detected with the ea leap, and the maximum voltage value was 4.6 V. The inter-electrode voltage was 3°9 V just before the splash occurred. pl (the amount of pressure drop was 0.7 V, the rate of voltage drop was 15- is 6 r9.

In this mackerel, even if the conditions are the same, the position at which the voltage between the electrodes is detected is different, so the ratio of 11 o is MU-A.
The threshold is 21%%B-B' threshold is 195G, C-C' threshold is 1
6-, and in this method of controlling the quality of the resistance #I performance with the voltage VII11, there is a drawback that the setting of the voltage drop ratio must be changed at the voltage threshold voltage O detection position. do.

However, as shown in the jIa diagram, the voltage drop is A-A.
- Seki "1" 0.6v% B-B' To, 7V, C-C
'Tor at 0.7V with a leap, this voltage drop does not vary depending on the detection position of the voltage between the electrodes and is approximately the same, so if the quality of the resistance is controlled by this voltage drop, the voltage drop between the electrodes The voltage detection position makes it possible to use the control device without performing GM.

[Brief explanation of the drawing]

1i1ii1 is a block diagram of a quality control device using a resistor III, FIG. 2 is a cross-sectional view of the resistor ***OW, and FIG. 3 is a waveform diagram showing the detected voltage of the voltage between the electrodes. Figure 2 α6■

Claims (1)

[Claims] Monitoring the voltage between the melting and forging voltages during resistance**. A method for controlling the quality of resistance welding in which the peak value of the Wl visual voltage is detected, p is set in advance from this peak value, and resistance** is terminated immediately when a large fE failure occurs.