JPS63299871A - Resistance welding control or monitoring device - Google Patents

Abstract

PURPOSE:To easily grasp information on an inconvenient phenomenon of the welding and the welding variance by displaying the change of the detected voltage or the change of the electric power calculated from a detected current between a couple of welding electrodes with materials to be welded between by the waveform change respectively. CONSTITUTION:A voltage signal SVX detected with a voltage detection circuit 44 between the couple of welding electrodes 20 and 22 with the materials 24 and 26 to be welded between is converted 52 into a DC and transmitted to a CPU 56 and displayed VW with a waveform on a display screen by a display control circuit 62. Moreover, the output voltage VTR which is made to a differential waveform from a welding current of a troidal coil 28 and voltage signals SIX outputted by a waveform restoration circuit 30 and a current effective value arithmetic circuit 32 are calculated together with the voltage signal SVX with an electric power arithmetic circuit 46 and made to an electric power value voltage signal SP. This is converted 54 into a DC and transmitted to the CPU 56 and displayed PW with a waveform in the same way. These displays VW and PW are monitored and the nonconformity and variance of the welding are detected and an input-output device 70 and a thyristor firing circuit 40 are operated by a control circuit 68 via the CPU to control a transformer 18.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a resistance welding control or monitoring device that provides minute information for monitoring the progress or quality of resistance welding.

(Prior art) As is well known, in resistance welding, the materials to be welded are sandwiched between a pair of welding electrodes and current is passed while applying pressure to generate Joule heat in the welding area, melting it and joining the materials metallurgically. It is a technology that

In general, in resistance welding, current is considered the most important welding condition that affects welding quality, so conventional resistance welding control devices and resistance welding monitoring devices mainly depend on current setting,
It is designed for functions such as control, constant monitoring, and monitoring.

(Problems to be Solved by the Invention) However, even if the current is monitored, the actual status or result of resistance welding cannot be determined in many cases.

For example, in the case of resistance welding using a constant current control method, the current is controlled to be constant, but even if this is monitored, the actual state of nugget formation and the presence or absence of dust cannot be determined. Rather,
In this case, the resistance or voltage between the welding electrodes changes, and by monitoring this it will be possible to know the state of nugget formation and the tool that is causing dust. Furthermore, if the power supplied to the materials to be welded can be monitored, more appropriate quality control can often be achieved.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a resistance welding control or monitoring device that provides useful information for monitoring the progress and quality of resistance welding.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a means for detecting a voltage applied between a pair of welding electrodes sandwiching a workpiece to be welded; and a voltage value obtained from the voltage detecting means. Based on this, the structure includes means for displaying the change in voltage between the welding electrodes during the energization period as a waveform.

In order to achieve the above object, the present invention further includes means for detecting a voltage applied between a pair of welding electrodes sandwiching a material to be welded; and means for detecting a current flowing through the material to be welded. ; Means for calculating the electric power to be supplied between the welding electrodes based on the voltage value and current value respectively obtained from the voltage detecting means and the current detecting means; Welding during the energization period based on the electric power value obtained from the power calculating means The present invention also includes means for displaying changes in the power supplied between the electrodes as a waveform.

(Function) According to the first configuration of the present invention, when the voltage between the welding electrodes changes during the energization period, the output signal (voltage value) of the voltage detection means changes accordingly, and this is detected by the waveform display means. Displayed as a voltage change waveform. This allows you to easily grasp the time characteristics of the voltage between welding electrodes in the form of a waveform diagram at a glance, and indirectly monitors nugget formation, dust generation, electrode life, etc. in constant current resistance welding. can do.

According to the second configuration of the present invention, when the power consumption between the welding electrodes (welding power) changes during the energization period, the output signal of the power calculation means changes accordingly, and the power change is detected by the waveform display means. Displayed as a waveform. As a result, the time characteristics of welding power can be easily grasped at a glance in the form of a waveform diagram, for example, the rise of welding power in constant power resistance welding.

It is possible to see changes in the fall. It is also possible to know the variations in the materials to be welded.

(Example) Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The figure shows the configuration of a resistance welding control device according to an embodiment of the present invention.

The commercial alternating current voltage Eo input to the input terminal 10.12 is supplied to the primary coil of the welding transformer 18 via a thyristor 14.18.
A welding current I flows from the secondary coil to the welded materials 24.26 sandwiched between the welding electrodes 20.22, generates Joule heat there, and metallurgically joins them together.

This resistance welding control device controls welding current I by switching between a constant current method and a constant power method.

The constant current type circuit has the following configuration and operation. A toroidal coil 28 is attached to the secondary conductor, and this coil 28 generates an output voltage VTR corresponding to the differential waveform of the welding current (2) when it flows. This output voltage VTR is converted into a voltage signal S1 representing the welding current I by a waveform restoration circuit 30 consisting of a bone contact circuit, and is converted into a voltage signal S1 representing the welding current I, and then converted to a voltage signal S1 representing the welding current I.
supplied to Arithmetic circuit 32 computes the effective value of welding current I every half cycle or every cycle, and supplies voltage signal SIX representing the value (current value) to one input terminal of comparator circuit 34 . The comparison circuit 34 receives the reference voltage SIA corresponding to the current setting value Io from the current setting circuit 36 at its other input terminal, compares it with the voltage signal S1x, and outputs an error signal ER representing the error between both signals. . This error signal E
R connects to the thyristor ignition circuit 40 via the switch circuit 38
The ignition circuit 40 controls the ignition angles of both thyristors 14 and 16 so that the comparison error becomes zero, that is, so that the actual welding current {circle around (2)} matches the set value Io.

The welding current (2) is controlled to be constant by such a constant current control loop.

Further, the constant power type circuit has the following configuration and operation. An AC voltage detection circuit 44 is connected between the welding electrodes 20 and 22, and this voltage detection circuit 44 calculates the effective value of the inter-electrode voltage V every half cycle or every cycle and calculates the value (voltage value). The voltage signal Svx representing the power calculation circuit 46 is applied to one input terminal of the power calculation circuit 46. The power calculation circuit 46 is a multiplication circuit, and the other input terminal is connected to the above-mentioned current effective value calculation circuit 3.
2, receives the voltage signal SIX representing the effective value of the welding current I, and performs half a cycle or l based on the flesh input signals SVX and SIX.
The welding power for each cycle is calculated and a voltage signal SP representing the power value is output. This voltage signal SP is applied to the comparator circuit 48.
It is compared with a reference signal Spa corresponding to the reference setting value Po from the power setting circuit 50, and an error signal EP indicating a comparison error between the two signals SP and Spa is obtained from the output terminal of the comparison circuit 48. This error signal EP is supplied to a thyristor firing circuit 40 via a switch circuit 38. The thyristor firing circuit 40 controls the firing angles of both thyristors 14 and 18 so that the comparison error is zero, that is, so that the actual welding power P matches the set value Po. Welding power P is controlled to be constant by such a constant power control loop.

The switch circuit 38 selectively supplies either the error signal ER or EP to the thyristor ignition circuit 40 in response to a control signal C8I from the CPU 5B, which will be described later, thereby controlling the constant current control loop and the constant power control loop. can be switched. In addition, the energization cycle control circuit 4
2 receives a control signal C82 from the CPU 56 and controls the thyristor ignition circuit 40 on and off to start or end energization.

Now, in this embodiment, the welding electrode 20.22 during the energization period
A function is provided to display on the screen a change in the voltage between and/or a change in the power (welding power) supplied between the welding electrodes 20 and 22 during the energization period as a waveform. This waveform screen display function will be explained below.

Voltage signals svx and sp output from the voltage detection circuit 44 and the power calculation circuit 46, respectively, are converted into digital signals by analog-digital (A/D) converters 52 and 54, and then taken into the CPU 5B. The CPU 5B processes the digitized voltage signals svx and sp as voltage change waveform and actual power waveform change data, respectively, and sends them to RA.
Write to M80. And according to the program,
or in response to a request from the control panel 68, the CPU 56
reads the notator of one or both of the voltage change waveform and power change waveform from the RAM 80 and displays it in the display control circuit 62.
to draw a voltage change waveform VW and/or a power change waveform PW on a display screen 64 such as a CRT.

This allows the operator to check the waveform VW/PW on the screen 64.
By observing, the time characteristics of the welding electrode voltage V and/or the welding power P can be grasped at a glance as a waveform diagram. For example, in the case of a constant current method, the voltage between the welding electrodes is proportional to the resistance value between the welding electrodes, so from the voltage change waveform, it is possible to monitor, for example, the formation of nuggets, the presence or absence of dust, or the degree of wear of the welding electrodes. Can be done. In the case of a constant power method, the rise and fall characteristics of welding power can be known from the power change waveform. It is also possible to know the variations in the materials to be welded.

Note that the ROM 58 stores a control program that defines various operations of the CPU 5B. Panel controller 66 is CP
Interfacing U5B and control panel 68. External memory 72 stores waveform data that cannot be stored in RAM 60 or waveform data that requires long-term storage. ■10 (input/output device) 70 interfaces the CPU 5B and the external memory 72, sends control signals CSI and C82 from the CPU 5B to the switch circuit 38° energization cycle control circuit 42, and also sends them remotely via the communication line 74. terminal or host computer. This communication function allows voltage change waveforms and/or power change waveforms to be observed remotely, which is useful in centralized management systems and the like.

Although preferred embodiments have been described above, various modifications are possible. For example, the function of the current effective value calculation circuit 32, the effective value calculation function of the voltage detection circuit 44, and the power calculation circuit 46
It is possible to replace the functions of CPU 5B or a separate CPU. Forms a constant current control loop and a constant power control loop.

The same applies to the other circuits 34, 38, 38, 42, and 48°50. Alternatively, the instantaneous values of the welding electrode voltage V and the welding current I can be directly A/D converted and imported into the CPU 5B, where voltage change waveform data can be generated, or welding power can be calculated and power change waveform data can be generated. It may be configured to generate.

In addition, the CPU 5B calculates the interelectrode voltage V and / during the energization period.
Alternatively, the average value, peak value, etc. of the welding power P may be calculated, and the calculated values may be displayed on the display screen 64 in a line diagram together with the voltage change waveform and/or the power change waveform. Furthermore, a printer may be connected to print out the waveforms on the display screen 64.

Although the resistance welding machine in the above-described embodiment is a single-phase AC type resistance welding machine, the resistance welding machine of the present invention can also be applied to other types of resistance welding machines such as three-phase AC type, DC type, and even inverter type. Control device is available. Further, the present invention is applicable not only to a resistance welding control device but also to a resistance welding monitoring device.

(Effects of the Invention) As described above, according to the present invention, changes in the voltage or power between the welding electrodes during the energization period are displayed in a waveform, so that the time characteristics of the voltage or power are displayed in the form of a waveform diagram. You can easily understand at a glance the state of nugget formation, presence or absence of dust, electrode life, power rise, etc.
You can obtain useful information for monitoring fallout and variations in the materials to be welded.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a resistance welding control device according to an embodiment of the present invention. 20.22... Welding electrode, 24.28... Material to be welded, 28... Toroidal coil, 30
... Waveform restoration circuit, 32 ... Current effective value calculation circuit, 44 ... Voltage detection circuit, 46 ... Power calculation circuit, 52゜54 ... A/D converter, 5
6...CPU160...RAM, 62...
...display control circuit, 64...display screen,
72...External memory.

Claims (4)

[Claims] (1) A means for detecting a voltage applied between a pair of welding electrodes sandwiching a material to be welded; and a waveform for detecting a change in voltage between the welding electrodes during an energization period based on the voltage value obtained by the voltage detection means. A resistance welding control or monitoring device characterized by comprising: means for displaying as . (2) The waveform display means includes means for converting the output signal of the voltage detection means into voltage change waveform data, means for storing the voltage change waveform data, and a voltage change waveform corresponding to the voltage change waveform data. A resistance welding control or monitoring device according to claim 1, comprising means for displaying a diagram on a screen. (3) Means for detecting the voltage applied between a pair of welding electrodes sandwiching the material to be welded, means for detecting the current flowing through the material to be welded, and voltage obtained from the voltage detection means and the current detection means, respectively. means for calculating the power supplied between the welding electrodes based on the voltage value and the current value, and a change in the power supplied between the welding electrodes during the energization period based on the power value obtained from the power calculation means. A resistance welding control device or a monitoring device, comprising: means for displaying the waveform as a waveform; and a resistance welding control device or monitoring device. (4) The waveform display means includes means for converting the output signal of the power calculation means into power change waveform data, means for storing the power change waveform data, and a power change waveform corresponding to the power change waveform data. A resistance welding control or monitoring device according to claim 3, comprising means for displaying a diagram on a screen.