JPS6178566A - Short-circuiting arc welding method and its equipment - Google Patents

Abstract

PURPOSE:To perform in succession a short-circuiting arc welding having good efficiency by performing a constant voltage control by a closed loop at arc generating time and a current control by a closed loop at short-circuiting time and by specifying the loading output current at the short-circuiting section time. CONSTITUTION:An arc 3 is forcibly generated with feeding a consumable elec trode 1 at constant speed, the arc detecting signal is transmitted from a voltage detector 5 to a switching circuit 11 and a preset output voltage is fed to the load. When the feeding of consumable electrode 1 is continued, the distance of the space with a base material 2 is gradually reduced and a short-circuit is reached from the arc 3, the voltage detector 5 immediately transmits a short circuit detecting signal and cuts off a voltage controlling circuit 6 with driving a switching circuit 11 and feeds to the load the output current Iz (Iz=Ia+Is+It) of an extraordinary waveform. Ia is for the arc current of immediately before the short circuit, Is for the preset rising part and It for the varied part increas ing nearly linearly according to the time lapse. The arc is thus generated stably and the arc welding of good efficiency is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to improvements in short-circuit welding arc welding, and particularly to the improvement of arc welding by controlling the output current supplied to the load to a predetermined waveform during the short-circuit section. The present invention relates to a method for continuously performing more stable and efficient short-circuit transfer tear arc welding, and an apparatus for carrying out the method.

The conventional short-circuit transfer arc welding method generates an arc by alternately shorting the consumable electrode to the base material and disturbing it while feeding the consumable electrode at a constant speed. jt? This is what we do.

The problem with doing this is that it is strongly desired to suppress the occurrence of baffle (especially noticeable when a short circuit occurs and when an arc occurs), and to ensure that the occurrence of sludge is always stable during welding. .

Conventionally, short-circuit currents have been controlled using the delay characteristics of DC reactors in order to meet these demands. Not only is it difficult to select a 7-volt conductor, but it also has the drawback that the time constant required when the current changes is extremely large.For this reason, the required inductance reaches several hundreds of μH, making it difficult to design and manufacture. There was a problem in that it was difficult and the manufacturing cost was high.

Furthermore, the current at the time of a short circuit is as large as several tens of OA, so a large inductance is required, and a very large glue handle is required. For this reason, in the past, a large inductance was obtained using an iron core, but in such cases, the problem of saturation of the iron core could not be ignored and various problems occurred.

Therefore, in recent years, efforts have been made to solve the vaporization problems of DC reactors (by inserting a phase delay element into the output feedback circuit, it is possible to effectively There are 11 different types of reactors that generate the effect of a DC reactor.

For example, the one proposed in Japanese Patent Application Laid-open No. 58-112659 is an improved version.

This device uses a switching control method using switching elements to control the output of the direct IT source, and is equipped with a circuit that causes the output control circuit to have a phase delay with respect to load fluctuations.
This phase delay amount is determined independently when the output is increased and when the output is decreased. It has a patented circuit configuration that allows adjustment, and has the advantage of being able to easily obtain the optimal output rise and fall speeds for welding without using a large DC reactor like in the past. Yes, the stability of welding is dramatically improved, and the bead shape can be controlled. 1 is possible.

Problems to be Solved by the Invention The present invention is a further improvement of the short-circuit transfer arc welding method using a phase-lag element, which is more efficient than the conventional method and has improved arc stability. The problem to be solved is to provide an arc welding method, and in particular, control of the waveform of the output 1i current, which has not been recognized in conventional methods, that is, the output that is supplied to the load in the event of a short circuit. By controlling the current to a specific waveform, droplet transfer is ensured in a short time, and at the same time, the above-mentioned problems are solved by suppressing the current value when arcing occurs and promoting heat generation for droplet transfer. It is something to be solved.

Means for Solving the Problems In order to solve the above problems, the inventors of the present invention have conducted various studies in implementing the short-circuit transitional arc welding method, and have patented the waveform of the output current during a short-circuit. By setting 2 and 2 as described in the claims, the droplet transfer is performed reliably in a short time, and at the same time, the '4 flow value at the time of arc generation is suppressed and the starting point for i3 droplet transfer is IIJI! We were able to generate an arc stably.

As a result, we learned that it became possible to generate an arc more stably, dramatically improving welding efficiency, and at the same time, welding could be performed continuously with less generation of svanta. The present invention was thus achieved.

That is, the method provided by the method of the present invention is a short-circuit transfer arc welding method in which short-circuiting and arc generation are alternately performed while feeding a consumable electrode at a constant speed, and when an arc is generated, constant voltage control is performed in a closed loop, In addition, in the event of a short circuit, the power control is switched to closed-loop control, and the waveform of the output current I supplied to the load during the short circuit period is changed to l.
z ”Ia+Is+lt (Here, 12 is the 7-ite flow immediately before the short circuit, Is is the preset rising edge, I
t is a change that increases approximately linearly over time. This is an arc welding device that is constructed by combining a constant voltage control circuit and 13 current control circuits, which drive a switch control circuit to control the output voltage and current supplied to the load in a closed loop. There it is,
Samurai: The constant voltage control circuit is driven by receiving an arc detection signal from a voltage detector that detects the load voltage when an arc occurs, and is driven by receiving an output signal from the voltage detector and preset in the switching control circuit. It comprises a voltage V@ control circuit that outputs a drive signal according to the tlII control value,
The IT current JI4 control circuit is driven in response to a short circuit detection signal from the voltage detector, and detects the load current. ! It comprises a current control circuit that receives an output signal from the detector and outputs a drive signal corresponding to a control value set in advance to the switching@iB circuit, and this ii f
Lf#I i11 circuit is 1, -1a+l54-I L
[Here, 1a is the arc current immediately before the short circuit, +3 is the preset rise, and +1 is the change that increases approximately linearly over time.] Current I! The gist of the invention is that the circuit is configured to supply the load to the load during the short-circuit section.

Functions and Effects of the Invention According to the method of the present invention, constant voltage control is carried out when an arc occurs, and when a short circuit occurs, the current is automatically switched to 11, and short circuit transition arc welding is performed continuously 1 time. Especially in the short-circuit section, the output J current I supplied to the load
2 is It-1a+ls+It (here, Ia is the current just before the short circuit, Is is the preset rising edge, lt+
It is a change that increases approximately linearly over time)
is controlled to a specific waveform defined by

A short t;) was detected by the capillary pressure extractor.
l+', -: Yo, kq 4 & straight 11; 1 arc center jA
A current obtained by adding a predetermined rising edge Is determined by 1 and 1 to the value with la as the 4th standard is instantaneously supplied to the It load, and the current is immediately increased. As time passes, this current is supplemented with a change defined by +1 that increases approximately linearly over time.

Therefore, when the contact resistance is large, the load is quickly turned into a droplet by applying a large current at a speed of t+, and if the contact resistance of the load increases as the core temperature of the droplet increases by 1, the predetermined change is 1. (As the current increases and is supplemented, the consumable electrode becomes small droplets and breaks off within a short time.)

As a result, a fine-grained bead is obtained, allowing efficient continuous welding work.

In addition, if a short circuit t'dLE limit setting circuit is provided in the current control circuit, the output current supplied to the load in the event of a short circuit is constantly monitored, which prevents the output current from increasing indefinitely during control. Preventable, reliable and stable fII
There is also the advantage that controlled short-circuit transitional arc welding can be carried out in series.

EMBODIMENTS OF THE INVENTION The method of the present invention will be described in detail below, together with the configuration of the apparatus, with reference to the accompanying drawings.

FIG. 1 shows the configuration of the apparatus of the present invention using a Bronk diagram.

As shown in the figure, the device of the present invention has switch blowfish control [!
It is composed of a constant voltage control circuit that drives the circuit IO and controls the output voltage and current supplied to the load in a closed loop, and a current control circuit. In addition, when a short circuit occurs, t-flow control is performed to perform short circuit (multi-row arc welding is performed once!!).

In the figure, 1 is a welding wire that is fed at a predetermined speed by a control system (not shown), 2 is a base material that is a broken weld member, and 3 is a welding wire that is generated when an arc occurs. 8 shows a contact arc, 4 is a t-current detector, 5 is a voltage detector, 6 is a voltage control circuit driven in constant voltage control mode, 7 is a current control circuit driven in current control mode, 8 is a smoothing circuit ,9 is! l
10 is a switching control circuit provided to supply the necessary voltage and current to the load; 11 is a constant voltage control circuit n and an electric current 11g + control circuit based on an arc detection signal from the voltage detector 5 and a short circuit output signal This is a switching means that alternately switches between.

Here, the voltage control circuit 6 is driven when the voltage detector 5 detects the occurrence of an arc, and in order to stably maintain the generated arc 3, eliminate wear, and heat and melt the arc 1, the switching control circuit 10 is connected in a closed loop. The arc generation section (
72 to TlJ, a constant output voltage V as shown in FIG. 2(a) is stably supplied to the load.

Further, the current control circuit 7 is driven when the voltage detector 5 detects a short circuit, and outputs an output current 2 as shown in FIG. 2(b) to the load during the short circuit period (Tl-72). The output current 1□ during the short-circuit period, which is supplied to the load by the current control circuit 7, rises sharply with Is as the rising edge with reference to the arc current +a immediately before the short-circuit. After rising by 1 min, it has a unique waveform that increases approximately linearly as time passes by 1 min as the short-circuit condition progresses.

In other words, 1ti+□ supplied to the load during the short circuit section is
! , =Ia+Is+It.'r is expressed as 'r.

[Here, Ia is the arc t just before the short circuit! S is a preset rise, and It is a change that increases approximately linearly over time. ] Figure 3 shows Pro 7 in Figure 1.
This is a more detailed configuration diagram of the line diagram, in which the switching control circuit 10 has an output realized by a power transistor or the like, I! Is the configuration in which the adjustment element 101 is driven by the driver +02 and the driver +02 on the pulse width side? 1
The pulse width of the drive pulse can be adjusted by turning iV3103.

Further, as the switching means 11, a switching circuit 11 with a design number is adopted after the pulse width control circuit +03, and when this switching circuit 11 receives an arc detection signal from the voltage detector 5 described above, it switches to the control mode. is selected for constant voltage control, and the voltage detector 5'@
Upon receiving the fault detection signal, the control mode is immediately switched to @, flow control.

A voltage control circuit 6 is provided after the switching circuit 11.
and 'Uj, /7iL are connected to the irrigation control circuit 7. In the embodiment, the voltage control circuit 6 includes an error amplifier 61 and a voltage setter 62.
Then, the output signal from the voltage detection rS5 (voltage supplied to the load) and the output signal from the voltage setting device 62 are compared, and the error output between the two is sent to the pulse width control circuit 103 via the switch knob circuit 11. ing.

Here, the voltage setting device 62 is used to define a control value at the time of constant voltage control.

On the other hand, in the embodiment, the current control circuit 7 includes a switching circuit 71, two error amplifiers 72, 73, and comparators 74. Furthermore, an I/V converter 75 and a short circuit current setting device 76
, a short-circuit current upper limit setter 77, and the switching circuit 7I enables selection switching between error amplifiers 72 and 73 using an inverted output signal from the comparator 74. is output, it is switched and connected to error amplifiers 72 to 73.

Here, the error amplifier 72 compares the output of the I/V converter 75 with the short-circuit current regulator 76 as a reference, and amplifies the output error between the two, and the error output is applied to the switching circuits 71 and 11. via the pulse width control circuit 103
The load is supplied with an output current 2 having the waveform shown in FIG. 2(b). That is, the output current supplied to the load during the short-circuit period is defined by the short-circuit current setting device 76, and becomes the short-circuit current 1 having a unique waveform shown in (bl) in FIG.

FIG. 4 shows a more detailed configuration of the short-circuit current setting device 76 that enables such control.

Here, the sample and hold circuit 762 samples the voltage signal corresponding to the output current 1a sent via the I/V converter 75, and performs the sampling every time it receives the short circuit detection signal from the voltage detector 5 described above. The rise position setter 763 outputs a voltage signal at a level determined according to the welding conditions in order to arbitrarily specify the rise Is necessary for fd control, for example. However, after the output current has risen for 15 minutes, the other integrating circuit 761 generates a slope value t that increases in a substantially linear manner determined by the change in It, that is, the time constant of the integrating circuit.
Define anδ.

Therefore, in this embodiment, error amplifier 72 is 1/
A sum signal obtained by adding the output signal of the V converter 75 and the outputs of the sample and hold circuit 762, the rising edge setting device 763, and the integration circuit 761 is manually generated, and these error signals are supplied to the switching circuit 72, and the error signals are supplied to the switching circuit 72. The current 1□ supplied to the load is controlled to have a waveform as shown in FIG. 2(b).

On the other hand, the comparator 74 compares the output level of the I/V converter 75 and the output level of the short-circuit current upper limit setter 77, and the output level of the I/V converter 75 exceeds the output level of the short-circuit current upper limit setter 77. In this case, the inverted output signal is sent to the switching circuit 71 and the error amplifier 7
2 to the error amplifier 73 and outputs its error signal.

As a result, when the comparator 75 outputs an inverted output signal, the signal sent to the pulse width control circuit +03 via the switching circuit ]l becomes the one set by the short-circuit current upper limit setting device 76, and the short-circuit current l□ becomes infinite. This will prevent the situation from increasing. Here, the setting value set by the short-circuit current upper limit setter 76 is normally specified so as not to cause spatter, so this upper limit setter 76 effectively suppresses the occurrence of spatter during a short circuit.
No. 1 will be displayed.

Next, the block diagram shown in Figure 3 and Figure 2;
- The operation of the circuit will be explained together with the method of the present invention with reference to waveform diagrams.

At the start of arc welding, appropriate pre-control is performed to facilitate the generation of the arc, and the consumable electrode 1 is fed at a constant speed to forcibly generate the arc 3.

When an arc 3 occurs, an arc ejection signal is sent from the voltage detector 5 to the switching circuit 11, and the voltage control circuit 7 is connected to the pulse width control circuit 103. As a result, the control becomes constant voltage control mode, and the voltage setting! The preset output voltage is supplied to the load in S72.

The output voltage {circle around (2)} supplied to the load at this time is as shown in FIG. 2(a).

However, as the consumable electrode 1 continues to be fed, the gap distance between the consumable electrode 1 and the base material 2 gradually decreases, leading to an arc and a short circuit.

Then, the voltage detector 5 immediately detects the state and outputs a short circuit detection signal.

In other words, in this state, the output voltage suddenly changes from several tens of ports to around zero ports. It should be configured so that it can be compared with the $ voltage)
.

In the embodiment shown in FIG. 1, the detection signal at this time drives the switching circuit +1. and immediately turn the voltage control circuit a.
The configuration is such that the current control circuit is disconnected and connected to the pulse width setting circuit 103, and at the same time a drive signal is also sent to the short circuit current setting device 76 to enable feedback control of the current set by the short circuit current setting device 76. It's supposed to be.

Therefore, when the voltage detector 5 outputs a short circuit detection signal, the switching circuit 11 outputs 1! Switching to the current gl +31 mode, the integrating circuit 761 is driven and the sample hold circuit 762 holds the sampled signal. As a result, the error amplifier 72 includes an integrating circuit 761.
．． + sample hold circuit 762, rise position setting device 763
The IJII 37 signal outputted from each of the
It is compared with the output current la sent from the current detector 4 via the V converter 75 (at the time of arc occurrence immediately before a short circuit), and the output it has the above-mentioned unique waveform defined by the above-mentioned addition signal. A stream I, will be supplied to the load.

As a result of these controls, when an arc occurs, the device enters the constant voltage t111 control mode, and when a short circuit occurs, the device enters the t-current control mode, and the output current 18 with the unique waveform shown in Fig. 2(b) is applied to the load. supplied, short-circuit transitional arc welding will be performed continuously.

In the present invention, the output current supplied to the load in the event of a short circuit is 1. Immediately before the short circuit, the output signal 1a from the sample and hold circuit 766 rises by the amount of the output signal Is from the rise position setter 763, and as the short circuit progresses further, the output signal IF (
(increases almost linearly) is supplemented, so the consumable electrode heated by the arc heat is divided into small droplets in a short time, making it possible to perform arc welding with high efficiency. be.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the schematic configuration of the device of the present invention;
Fig. 2 is a waveform diagram of the output voltage and output current controlled by the method of the present invention, Fig. 3 is a block diagram showing the device shown in Fig. 1 in more detail, and Fig. 4 is a detailed diagram of the short-circuit IT setting device. FIG. 2 is a block diagram showing the configuration. (Explanation of symbols) In the figure, 1 is a consumable electrode, 2 is a base material, 3 is an arc generated during welding, 4 is a current detector, 5 is a voltage detector, 10
is a switching control circuit.

Claims (3)

[Claims] (1) In the short-circuit transfer arc welding method, which alternately short-circuits and generates an arc while feeding the consumable electrode at a constant speed, when an arc occurs, closed-loop constant voltage control is performed, and when a short-circuit occurs, the switch is switched to closed-loop current control. Then, the output current I_2 supplied to the load during the short circuit section is I_2 = Ia + Is + It [where Ia is the arc current immediately before the short circuit, Is is the preset rise, and It is approximately linear as time passes. A short-circuit transitional arc welding method characterized by controlling the amount of change to increase. (2) An arc welding device configured by combining a constant voltage control circuit and a current control circuit that drive a switching control circuit to control the output voltage and current supplied to the load in a closed loop, comprising: The constant voltage control circuit is driven by receiving an arc detection signal from a voltage detector that detects the load voltage when an arc occurs, and receives an output signal from the voltage detector to perform control set in advance in the switching control circuit. The current control circuit is configured to include a voltage control circuit that outputs a drive signal according to a value, and the current control circuit is driven in response to a short circuit detection signal from the voltage detector, and outputs an output from the current detector that detects the load current. The current control circuit receives a signal and outputs a drive signal according to a control value set in advance to the switching control circuit, and this current control circuit is configured by I_2=Ia+Is+It [where Ia is the arc current immediately before the short circuit. , Is is a preset rise, and It is a change that increases approximately linearly over time.] The output current I_2 is supplied to the load during the short-circuit period. A short-circuit transitional arc welding device comprising: (3) The arc welding apparatus according to claim 2, further comprising a short-circuit current upper limit setting device that limits the upper limit value of the output current supplied to the load by the current control circuit to a preset value.