JPH03474A - Method for controlling output of consumable electrode arc welding power source - Google Patents

Abstract

PURPOSE:To control the welding current and voltage based on optimum reference waveforms by correcting the reference waveforms by an arithmetic means so that a variance state of the waveforms of the welding current and voltage controlled after an arc is started is regulated in the prescribed range. CONSTITUTION:After the arc is started, the welding current and the welding voltage are controlled according to the reference waveforms generated by a waveform generation part 16 by a feedback control system of a voltage detection part 11, a current detection part 12 and the waveform generation part 16 and the variance state is calculated by a CPU of a microcomputer 15 from subsequent variance of the detected waveforms of the welding current and welding voltage based on the outputs of the current detection part 12 and the voltage detection part 11 and it is detected by the CPU whether or not the variance is within the prescribed range. If the calculated variance state exceeds the prescribed range, the short-circuit time and the arc time, for instance among various parameters to correct the reference waveforms are controlled to correct both reference waveforms of the waveform generation part 16 to the optimum waveforms and the variance state of the waveforms of the welding current and voltage is suppressed within the prescribed range and the stable arc is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling the output of a consumable electrode type arc welding power source for controlling the output of a welding power source.

[Conventional technology]

Conventionally, a source for so-called short-circuit transfer type consumable electrode arc welding has been constructed as shown in FIG. 3, for example.

In the figure, (1) is a PWM inverter configured with an inverter main circuit consisting of a rectifier circuit that rectifies the output of a three-phase AC power supply and a switching element that converts the output DC of the rectifier circuit into AC by switching, and (2) is 1
Output transformers (3a) and (8b) with both ends of the next coil (2a) connected to both output terminals of the PWM inverter (1)
are two rectifier diodes whose anodes are connected to both ends of the secondary coil (2b) of the transformer (2), and (4) are two rectifier diodes whose anodes are connected to both ends of the secondary coil (2b) of the transformer (2).
), (6) is a consumable electrode wire that is fed to the torch (4) by the feeding device (7) and is powered through the torch (4), and (8) is the welding base material. and is connected to the intermediate tap (1) of the secondary coil (2b).

At this time, shielding gas is supplied to the torch (4),
The arc generated between the wire (6) and the base material (8) is shielded.

(9) is a voltage detection transformer installed between the torch (4) and the base metal (8), QO is the current transformer installed in the current path between the base metal (8) and the intermediate tap (1), and αD is the voltage detection transformer installed between the torch (4) and the base metal (8). Detection transformer (9
), Qz is a current detection unit that detects welding current from the output signal of current transformer α0 and outputs a current detection signal,
q3 is a setting section that outputs voltage and current setting signals, 04
) is a waveform generator, into which the voltage, current detection signal and setting signal are input, and the welding voltage reference waveform and welding current are determined from the time by the built-in time constant circuit and the voltage and current setting values by the setting signal. A PWM inverter (1
) outputs PWM control pulses to the inverter main circuit.

At this time, the reference waveforms of the welding current and welding voltage are uniquely determined by the set values of the voltage and current, and the short circuit time and arc time by the time constant circuit built in the waveform generating section α.

However, since the arc time is determined to some extent by the composition of the wire used, for example, the time constant that determines the arc time and short circuit time is made variable, or linked to the voltage and continuously variable, so that the welding current and welding The voltage reference waveform is flexible.

[Problem to be solved by the invention]

In addition to the above, the arc time and short circuit time are also affected by other welding conditions such as the wire diameter. If conditions are different and it is not possible to respond to these and the reference waveform is not optimal, the actual welding current and welding voltage waveforms will vary irregularly and greatly, and this variation will cause bead defects and poor welding strength. There is a problem that something like this occurs.

The present invention has been made with the above-mentioned points in mind, and the present invention has been made so that the waveform variations of welding current and welding voltage are within a predetermined range.
The purpose of this invention is to correct the waveform data of the reference waveforms of the welding current and welding voltage so that the welding current and welding voltage can be controlled based on the optimal reference waveforms.

[Means to solve the problem]

In order to achieve the above object, in the output control method of the consumable electrode type arc welding power source of the present invention, welding conditions, welding current, and welding voltage are controlled based on wire composition, diameter, base material, welding speed, etc. storing the waveform data of the selected welding conditions in the storage means, reading out the waveform data of the selected welding conditions from the storage means, creating reference waveforms of welding current and welding voltage from the read out waveform data, and after starting the arc, The welding current and the welding voltage are controlled according to the created reference waveforms t, and the dispersion state is calculated by a calculation means from the dispersion of the detected waveforms of the welding current and welding voltage after that, and the dispersion state is within a predetermined range. If the variation state is within the predetermined range, welding is performed, and when the variation state exceeds the predetermined range, the calculation means corrects both the reference waveforms so that the variation state falls within the predetermined range.

[Effect]

In the above configuration, the welding current and voltage after arc start are controlled according to the reference waveform based on waveform data of appropriately selected welding conditions, and the dispersion state is determined from the dispersion of the welding current and voltage waveforms by the calculation means t. is calculated, and the reference waveform is corrected by the calculation means so that this dispersion state is within a predetermined range. Therefore, a stable arc is maintained, good welding is performed, and no matter what kind of wire is used or what kind of wire is used. Even when the welding conditions are set, a stable arc is maintained, and it is possible to accurately respond to changes in external conditions, including fluctuations in the workpiece.

〔Example〕

An example will be described with reference to FIG.

In the figure, the same symbols as in Figure 2 indicate the same or equivalent ones, and the difference from Figure 2 is that the system is equipped with a memory section consisting of ROM RAM as a storage means and a CPU as a calculation means. A microcomputer (hereinafter referred to as microcomputer) 09 is provided, and a waveform generating section Cej is provided which creates and generates reference waveforms of welding current and welding voltage based on the output data of this microcomputer a9.

Then, in the memory section of microcomputer 09, the components of the wire,
Waveform data of welding current and welding voltage is stored in advance for each welding condition based on diameter, base material, welding speed, current, voltage, etc., and by selecting welding conditions close to the desired conditions, the CPU , the waveform data of the selected welding condition is read out from the memory section and is sent to the waveform generation section ae.
The waveform generator σG creates reference waveforms for welding current and welding voltage from the input waveform data, and then arc start is performed.

Next, after arc start, voltage and current detection section αυ,a
2I and the feedback control system of the waveform generator H,
The welding current and welding voltage are controlled according to the reference waveform created by the generation section αQ, and the current and voltage detection section (2)
, based on the output at 0°C, the state of the variation can be determined from the variation in the detected waveforms of the subsequent welding current and welding voltage.
The CPU determines whether the calculated variation state is within a predetermined range, and if it is within the predetermined range, welding is performed using the reference waveform.

On the other hand, when the calculated dispersion state exceeds a predetermined range, among various parameters for correcting the reference waveform, for example, short circuit time and arc time are controlled, and the waveform generation part a0
The same reference waveform in is corrected to the optimum waveform, variations in the waveforms of welding current and welding voltage are suppressed within a predetermined range, a stable arc is maintained, and good welding is performed.

By the way, when a certain welding condition is selected, the welding voltage waveform and welding current waveform after arc start will be as shown in Fig. 2 (a) and (b), for example, and if the waveform data of the selected condition is not optimal, , these voltage and current waveforms vary widely, and the short circuit time Ts and arc time Ta vary greatly, making it impossible to maintain a stable arc state.

At this time, when the detected voltage is lower than the threshold value indicated by the dashed line in FIG. 2(a), it is determined as the short circuit time, and when it is higher, it is determined as the arc time.

As shown in FIGS. 2(a) and 2(b), when there are large variations in the welding voltage waveform and welding current waveform, the reference waveform is corrected to the optimum waveform by the microcomputer α9 as described above, and the welding Variations in voltage waveforms and welding current waveforms are suppressed within a predetermined range.

Here, the parameters for optimally correcting the reference waveform are not limited to the short-circuit time and arc time mentioned above, but also include the short-circuit current and voltage control width, but the parameters are selected as appropriate depending on the state of dispersion of the welding voltage and current waveform. Alternatively, these parameters may be controlled in combination.

In addition, the waveform data of the reference waveform after correction is accumulated and stored in the memory section of the microcomputer αG, and by using these as data for parameter control when correcting the waveform during the next welding, it is possible to control the welding voltage. , the variation state of the current waveform can be suppressed to a smaller extent, and such a learning function enables highly accurate welding.

Therefore, no matter what kind of wire is used or what kind of welding conditions are set, a certain amount of arc will be generated, and then from the detected waveforms of welding voltage and current, it is possible to suppress the dispersion of these detected waveforms within a predetermined range. A stable arc can be maintained, and changes in external conditions, including fluctuations in the workpiece, can be responded to immediately and accurately.

Note that a printout function and a communication function may be added to expand the scope of application.

In addition, although a microcomputer was used in the above embodiment, [f
Needless to say, hardware logic or arithmetic elements may be used.

〔Effect of the invention〕

Since the present invention is configured as described above, it produces the effects described below.

The welding current and voltage after arc start are controlled according to the reference waveform based on the waveform data of appropriately selected welding conditions, and the dispersion state is calculated from the dispersion of the welding current and voltage waveforms by the calculation means. Since the reference waveform is corrected by the calculation means so that it falls within the predetermined sound range, a stable arc can be maintained no matter what kind of wire is used and what kind of welding conditions are set, and fluctuations in the workpiece can be avoided. This makes it possible to respond accurately to changes in external conditions, including changes in external conditions, and to perform high-precision and good welding.

[Brief explanation of drawings]

1 and 2 show an embodiment of the output control method of the consumable electrode type arc welding power source of the present invention, and FIG. 1 is a wiring diagram,
FIGS. 2(a) and 2(b) are waveform diagrams of welding voltage and welding current, and FIG. 3 is a connection diagram of a conventional example. (6)... wire, (8)... welding base material, a-...
- Voltage detection section, (2)... Current detection section, α9... Microcomputer, aQ... Waveform generation section.

Claims (1)

[Claims] (1) Consumable electrode wire, the welding current flowing through the welding base metal and the welding voltage between the wire and the base metal are controlled, and the consumable electrode causes short circuits and arcs to alternately occur between the wire and the base metal. In the output control method of an electrode-type arc welding power source, waveform data of welding current and welding voltage is stored in a storage means for each welding condition based on wire composition, diameter, base material, welding speed, etc. reading the waveform data of the welding conditions from the storage means, creating reference waveforms for welding current and welding voltage from the read waveform data, and after starting the arc, controlling the welding current and welding voltage according to the created reference waveforms. The voltage is controlled, and the dispersion state is calculated by a calculating means from the dispersion of the detected waveforms of the welding current and the welding voltage thereafter, and if the dispersion state is within a predetermined range, welding is started, and the dispersion state is within the above-mentioned range. An output control method for a consumable electrode type arc welding power source, characterized in that both the reference waveforms are corrected by the calculation means so that the variation state falls within the predetermined range when the variation exceeds the predetermined range.