JPH0446675A - Pulse arc welding method - Google Patents

Abstract

PURPOSE:To hold the quantity of energy supplied to a welding wire constant and to perform stable welding by carrying out arithmetic processing on a detected welding current, integrating it and changing over to application of a base current when an integrated level attains a specified level at the time of applying a peak current. CONSTITUTION:At the time of applying the peak current, an arithmetic circuit 10 carries out specified arithmetic processing on the detected welding current and outputs it to a current integration circuit 11 to integrate it. An integrated level discrimination part 12 outputs a peak current application finishing signal to a current application changeover part 3 when the integrated level attains the predetermined specified level. The current application changeover part 3 stops the output of a peak current application signal and outputs a base current application signal instead.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a novel pulsed arc welding method.

[Prior art] This type of pulsed arc welding uses a peak current ■p higher than the critical electric current TILIc required for droplet transfer, and a critical current 1
Welding is performed by alternately applying a base current 1b lower than c to the welding wire, and applying a peak current p to the welding wire to cause the welding wire to separate from the droplet due to the pinch effect, but there are many factors that need to be set. Therefore, in general, the welding average current 1a (wire feeding speed), peak current Ip and its energization period tp, base current 1b, and welding average voltage Ea are set according to the welding conditions, and the base current energization period tb is variably controlled. Generally, automatic control is performed so that the welding average voltage Ea becomes a specified level.

However, with this method, the peak current ip cannot be set continuously, making it difficult to perform optimal and fine-grained control according to various welding conditions depending on the welding wire and welding base material, and improvements are desired. Ta.

[Problems to be Solved by the Invention] The present invention was achieved as a result of the inventor's intensive studies in view of the above circumstances, and it enables the peak current to be variably set, so that the average welding voltage becomes a predetermined value. The purpose of this invention is to provide a new pulsed arc welding method that automatically controls the optimum peak current application period for one pulse one droplet transfer according to the set peak current while controlling .

[! ! Means for Solving the Problem] The present invention according to claim 1, proposed to achieve the above object, integrates the welding current (peak current) after performing predetermined calculation processing when applying the peak current. When this integral level reaches a predetermined level, the peak current is stopped and the base current is switched to the base current. On the other hand, in order to control the energization cycle so that the welding average voltage matches a predetermined welding average voltage reference value, the base current energization is stopped and the peak current energization is switched to energization. Accordingly, when the peak current is variably set, the peak current application period is automatically controlled based on the energy applied to the welding wire by the application of the peak current.

The present invention according to claim 2 provides that when the base current is applied, the welding current (base current) is subjected to predetermined arithmetic processing and then integrated, and when the subsequent peak current is applied, the welding current (peak current) is integrated when the base current is applied. After performing predetermined arithmetic processing different from the above, integration is performed, and when the sum of these integration levels reaches a predetermined value, the peak current supply is stopped and the base current supply is switched. On the other hand, to control the energization cycle so that the welding average voltage matches a predetermined welding average voltage reference value, the base current energization is stopped and the peak current energization is switched to energization.

Accordingly, when the peak current is variably set, the peak current application visit is automatically controlled based on the sum of the energy added to the welding wire by applying the base current and the energy added to the welding wire by applying the peak current.

[Function] In the present invention according to claim 1, when peak current is applied,
The detected welding current is integrated after performing predetermined arithmetic processing, and when this integration level reaches a predetermined level, the peak current is stopped, while the detected welding voltage is integrated into a predetermined welding average. The energization cycle is controlled so as to match the voltage reference value, thereby performing pulse arc welding by alternately switching between the peak current and the base current.

In the present invention according to claim 2, when the base 1 is energized,
The detected welding current is subjected to predetermined arithmetic processing and then integrated, and when the peak current is subsequently applied, the detected welding current is subjected to predetermined arithmetic processing and then integrated, and the sum of these integration levels is calculated at a predetermined level. When the peak current level is reached, the peak current is stopped, and the energization cycle is controlled so that the detected welding voltage matches a predetermined welding average voltage reference value, thereby alternating the peak current and base current. Switch to energize and perform pulse arc welding.

[Example] Below are the attached drawings. The present invention will now be described in detail.

FIG. 1 is a block diagram showing the main structure of a welding apparatus for carrying out the pulse arc welding method of the first invention (corresponding to requirement 1 of II).

In the first invention, the peak current 1p can be manually variably set, and at the same time, by manually setting each reference value of the welding average current, base current, and welding average voltage, the welding average voltage Ea can be adjusted to the welding average voltage Ea. The optimum peak current application period tp for transferring one droplet per pulse is automatically controlled while controlling the current application period so as to match the voltage reference 11Er.

In FIG. 1, 1 is a peak current energization period control means; 2
3 is an energization cycle control means for controlling the energization period T, which is the sum of the peak current energization period tp and the base current energization tb; 3 is an energization switching unit that switches and holds and outputs the base current energization signal or the peak current energization signal; and 4 is an energization switching unit This is a welding voltage setting section that sets a welding average voltage reference value Er.

Note that the diagram omits a current control means for controlling the welding current in accordance with a peak current energization signal or a base current energization signal output from the energization switching unit 3 (described later), and this current control means Peak current set by ■
Negative feedback control is performed so that p or base current Ib is stably energized.

The peak current energization period control means 1 outputs a timing signal for terminating the energization of the peak current 1p.
an arithmetic port nio that performs the arithmetic operation of raising tA to the power), and an arithmetic circuit 10
Current integrator circuit 1 that integrates the arithmetic processing results output from
1, and an integral level determination unit 12 that outputs a peak current energization end signal when the integral value of the current integrating circuit 11 reaches a predetermined level L1, and resets the current integrating circuit 11 to clear the integral level. and an analog switch 5WIO that closes only during the period when it is receiving the peak current energization signal output from the energization switching section 3 and outputs the current signal processed by the arithmetic circuit IO to the current integration circuit 11.
It is equipped with

The energization cycle control means 2 generates a timing signal for starting peak current energization (signal for terminating base current energization) by controlling energization cycle T, which is the sum of peak current energization period tp and base current energization period tb. For this purpose, the welding voltage E between the welding wire and the welding base metal is compared with the welding average voltage reference value Er set by the welding voltage setting section 4, and the error signal is obtained. Voltage error amplification circuit gl! 20, and according to the error signal level output from the welding voltage error amplification circuit 20, the welding voltage average value Ea is adjusted to match the welding average voltage reference value Er]
V/F that outputs a peak current energization start signal for each jllT
A conversion circuit 21 is provided.

The welding method of the first invention carried out in such a configuration will be explained below with reference to the waveforms of each part shown in FIGS. 2(a) to (i). Note that corresponding parts in FIG. 1 are designated with corresponding symbols (a) to (j).

Depending on the welding conditions, welding average current 1a, peak electric current m I
p, base current 1b, and welding average voltage Ea are set.

■When the peak current energization signal is output from the energization switching unit 3, the analog switch 5 of the peak current energization visit control means 1
WIO closes.

■The arithmetic circuit 10 performs predetermined arithmetic processing (calculation of raising the peak current 1p to the A power) on the detected welding current (peak current 1p) and outputs it to the current integrating circuit 11. This arithmetic processed signal is integrated.

■The integral level determination unit 12 monitors the integral level of the current integrating circuit 11, and when the integral level reaches a predetermined value L1, it outputs a peak current energization end signal to the energization switching unit 3 and , reset the current integration circuit 11 and clear the integration level.

■The energization switching unit 3 receives the peak current energization end signal,
The output of the peak current energization signal is stopped, and the base current energization signal is held and output instead. As a result, the analog switch 5w1o is opened, and the signal output from the arithmetic circuit 1O to the current integration circuit 11 is cut off.

■On the other hand, welding voltage error amplification circuit 2 of energization period control means 2
0, the detected welding voltage E is compared with the welding average voltage reference value Er set by the welding voltage setting section 4, and an error signal thereof is output.

■The V/F conversion circuit 21 outputs a peak current energization start signal every cycle T according to the error signal level output from the voltage error amplifier circuit 20 so that the welding average voltage Ea matches the welding average voltage reference value Er. Output to the energization switching section 3.

(2) The energization switching unit 3 receives the peak current energization start signal output from the energization cycle control means 2, and holds and outputs the peak current energization signal. By this peak current energization signal, the analog switch 5WIO of the peak current energization period control means 1
closes again. By repeating these operations (1) to (2), the peak current Tp and the base current 1b are alternately applied.

In this way, in the first invention, the peak current energization period control means 1 calculates equivalently the thermal energy applied to the welding wire by integrating the calculated peak current Tp, and calculates the amount of energy applied to the welding wire. Since the application of the peak current Ip is terminated and switched to the base current 1b when it reaches the optimum value for transition to 1-pulse l-immersion, even if the peak current If is set variably, the droplet detachment will not reach its peak. It is possible to effectively prevent the occurrence of spatter within the current application period tp, and to perform good pulse arc welding with a reduced amount of spatter even when the welding average voltage Ea is low and a short circuit occurs during droplet detachment. becomes possible.

Furthermore, when the peak current 1p is set low, the arc sound becomes softer, reducing the burden on the operator.

Furthermore, since the peak current energization period tp is controlled by the amount of energy supplied to the welding wire by the peak current tp, if the primary side power supply voltage drops or the secondary side welding cable is long, the energizing current waveform will change due to the cable inductance. Even if the welding wire becomes dull, the peak current energization period tp is automatically controlled to be longer so that a certain amount of energy is applied to the welding wire, making it possible to perform stable pulsed arc welding. .

Next, FIG. 3, which explains the second invention (corresponding to claim 2), is a block diagram showing the main part configuration of a welding device that implements the pulse arc welding method of the second invention.
This method differs from the method according to claim 1 described above in the configuration of the peak current energization period control means 1', and other parts are the same, so the same reference numerals are given and the explanation thereof will be omitted.

The arithmetic circuit lO1 of the peak current energization period control means 1' is as follows:
During the period when the base current energization signal is received from the energization switching unit 3, a predetermined calculation process (
While performing the calculation of raising the welding current I to the B power, the energization switching section
During the period when the peak current energization signal is received from the base current energization signal, a predetermined calculation process (calculation of raising the welding current I to the A power) is applied to the welding current I (peak current 1p), which is different from the period when the base current energization signal is received. In addition, the integral level determination unit 12 determines that the integral output level output from the current integrating circuit 11 is at a predetermined level L2 (assuming that the integral constant in the current integrating circuit 11 is the same), the integral output level output from the current integrating circuit 11 is The peak current energization end signal is output when the peak current energization end signal is exceeded, which is set higher than the predetermined level L1 in the first invention in consideration of the integral output level.
The operation of the current integrator vsll is the same as in FIG.

In addition, the integration constant (integration time constant) in the current integration circuit 11
is the same as the first invention, but when changing the integral constant, the predetermined level L2 may be changed correspondingly.

The welding method of the second invention implemented in such a configuration will be explained with reference to the waveform diagrams of FIGS. 4(a) to 4(1). In addition, the corresponding symbols (a) to (i) are attached to the third ryJ.

■When the base current energization signal is output from the energization switching unit 3, the calculation multiplier of the calculation circuit 10' is switched to B, and the detected welding current ■ is subjected to a predetermined calculation process (base current 1b is changed to B
Multiplication operation) is applied and the current integration circuit is integrated.

(2) On the other hand, when the peak current energization start signal is output from the energization cycle control means 2, the peak current energization signal is held and output from the energization switching section 3, and the arithmetic multiplier of the arithmetic circuit lO' is switched to A. As a result, the arithmetic circuit 10' performs a predetermined calculation (peak current 1
A calculation of raising p to the A power) is performed, and the current integration circuit 11 integrates the current.

■When the integral level integrated in the current integration circuit 11 from the base current conduction period tb to the peak current conduction period tp reaches the predetermined level L2 in this way, the integral level determination unit 12 issues a peak current conduction end signal. The base current energization signal is held and outputted from the energization switching section 3, and the integral amount of the current integration circuit 11 is reset, and the operation returns to (2) again.

By repeating the operations (1) to (2) above, the peak current (2) p and the base current Ib are alternately applied.

In this way, in the second invention, the peak current energization period control means 1' controls the energy applied to the welding wire by the base current 1b and the energy applied to the welding wire by the peak current Ip to each other. It is equivalently determined by integrating after calculation processing, and when this amount of energy reaches the optimum value for one droplet transfer per pulse of the welding wire, the application of the peak current Ip is terminated and the base current rb is As in the first invention described above, droplet detachment can be effectively prevented from occurring within the peak current application period tp, and the welding voltage E is low enough to prevent droplet detachment. Even if a short circuit sometimes occurs, it is possible to perform good welding with a reduced amount of spatter.

In addition, similar to the first invention, when the peak current 1p is set low, the arc noise becomes soft and the burden on the operator is reduced, and the primary side power supply voltage decreases and the inductance of the secondary side cable is reduced. Stable welding can be achieved through control that takes into account the effects of

Next, the technical background of the present invention will be explained.

Figure 5 shows the case where a 1.2 mmφ mild steel welding wire is used and argon gas is used as the shielding gas.
This is a graph obtained by actually measuring the value of the peak current energization period tp required to cause one pulse and one droplet transfer by changing the peak current 1p, and the base current! The data obtained when b is fixed at 50 A and the welding average current Ia is varied, and the data obtained when the welding average current Ia is fixed at 200 A and the base current 1b is varied are plotted. According to this graph, when the average welding current 1a is the same, the larger the base electric current tyLIb is, the smaller the peak current application period tp required to cause one pulse-one welding transition,
It can also be seen that when the base current 1b is the same, the peak current application period tp required to cause droplet detachment increases as the welding average current 1a increases.

In this graph, the inventor found that the peak current energization period tp required for one pulse and one molten metal transition varies depending on the sum of the energization energy in the base current energization period tb and the peak current energization period tp. Focusing on the fact that the energizing energy can be obtained almost equivalently by integrating the base current and the peak current raised to the power of a predetermined multiplier, the first invention calculates the energizing energy by the peak current energizing. In the second invention, the peak value is obtained from the base current energization period tb by performing arithmetic processing on the welding current I during the period tp and then integrating it. Equivalently obtained by performing predetermined arithmetic processing on the welding current I over the amount of current flowing tp and then integrating it,
The optimum peak current energization period tp was successfully controlled using the obtained integral value (energy amount), and the present invention is characterized in that the peak current energization period tp is controlled by the energization energy.

! Figure 6 shows the welding current! in the pulsed arc welding method of the present invention. This graph shows the progress of droplet detachment with respect to time changes.In the peak current application period +4 tp, by applying a peak current [p to the welding wire W, the tip of the welding wire W is constricted due to the pinch effect caused by the applied current. The droplet W is brought into a state immediately before detachment, and the droplet Wa is transferred to the base metal M side after the peak current energization period tp is switched to the base current energization period tb. By controlling in this way, the welding average Even when the voltage Ea is low and a short circuit occurs during droplet detachment, it is possible to perform good welding with a reduced amount of spatter.

Figures 7(a) and 7(b) show how the droplet detachment cycle changes in pulsed arc welding, depending on the magnitude of peak current rp, peak current conduction period tp, and base current Tb. be. That is, from Fig. 5, welding average current 1a = 200A (welding wire feeding speed = 7.3m/
m1n), when peak current 1pl = 45OA and base current 1b = 50A are applied to a 1.2mmφ mild steel wire, the minimum peak current application period tP1 required for one pulse and one droplet transfer is approximately 1.7ms. It can be seen that (at this time, the energization period TI=4.53 m5).

Fig. 7 (a) *See), and peak current 1p2 = 350
A. When base current 1b = 50A is applied, the minimum peak current application period tP required for one pulse and one droplet transfer
2 is approximately 3.25 m5 (at this time, the energization period T1 = 6.5 ms).

Refer to Fig. 7(b) -) Average welding current 1a
.

When the base current 1b is constant, if the peak current ■p increases, the amount of droplets detached by one pulse decreases and the current application period T becomes shorter; conversely, if the peak current tp decreases, the droplets detach by one pulse. It can be seen that the amount of droplets increases and the energization period T becomes longer.

In the first invention, the peak voltage t! Although Ip is calculated and integrated, according to the above data, Ipl^Xt
If the multiplier A is set to satisfy pl=Ip2^Xtp2, the amount of energy applied to the welding wire can be kept constant even if the peak current Ip is changed, and the peak current application period tp can be set to 1 pulse l droplet. It becomes possible to automatically control the optimum value required for transition.

That is, in the first invention, if the base current 1b is compensated according to the setting of the welding average current reference value 1r (the base current Ib is also increased or decreased at the same time according to the increase or decrease in the welding average current reference value Ir), the peak current It is possible to equivalently obtain the amount of energy applied to the welding wire by simply performing arithmetic processing and integration for 1p.

Further, in the second invention, in addition to the peak current ■p, the base current 1b is also integrated after calculation processing, but similarly, (Ipl^Xtpl) + (Ibl"Xtbl) = (
If the multiplier B is determined to satisfy Ib2'Xtb2) + (Ib2'Xtb2), the energy amount to the main welding wire can be equivalently determined when both the peak current Ip and the base current 1b are changed. Therefore, compared to the first invention, it is possible to more accurately determine the equivalent energy applied to the welding wire, and the peak current energization period tp can be similarly automatically controlled to the optimum value.

Figures 8(a) and 8(b) show that in the present invention, when the welding average electric current aIa and the peak current Ip are constant, the droplet transfer rate per pulse l depends on the magnitude of the base electric current t'iLIb. This figure shows how the optimum peak current energization period tp of 1 gI (the period until the state immediately before droplet detachment) changes. That is, when the base current Ib is low, the energy contributing to droplet detachment due to the base current 1bl is low, as shown in FIG. It is necessary to lengthen the current conduction period tpa, and conversely, the base current tb
When is high, as shown in the same figure (b), since the energization of the welding wire by the base current 1b2 is large, the peak current application period tp is set so that the droplet does not detach during the peak current application period tpA. must be shortened.

FIG. 9 is a block diagram showing an example of the configuration of a pulse arc welding apparatus for carrying out the above-described pulse arc welding method of the first invention.

In the figure, 1 is a peak current energization period control means, 2 is an energization period control means, 3 is an energization switching section, and 4 is a welding voltage reference setting section. These are the same as in FIG. 1, so they are given the same reference numerals. are doing. 5 is a peak current 1p and a base current according to the switching signal of the energization switching section 3! 6 is a current control unit that outputs an energization control signal for switching and energizing the welding device, and 6 is a startup control unit that outputs a compensation signal for promoting arc generation and expansion when the welding device is started. AMP is a welding current amplification circuit that amplifies the welding current, ATT is an attenuator circuit that attenuates the welding voltage, and 7 is an inverter INV according to the energization control signal output from the current control means 5.
8 is a wire feeding control section that controls the feeding of the welding wire W. In addition, REC is a rectifier circuit unit that rectifies the three-phase AC voltage, T is a transformer that isolates and transforms the switching voltage output from the inverter INV, and DI
, D2 is a diode for full-wave rectification of the power output from the transformer T, S is a shunt resistor for extracting the welding current as a voltage level, L is an axle, and M is a welding base material.

The peak current energization period control means 1 includes an arithmetic circuit 101
Since the current integrator GALL and the analog switch 5WIO are the same as in FIG. 1, they are given the same reference numerals and their explanation will be omitted. Further, the integral level determination unit 12 includes a current integrating circuit 1
Comparator 1 outputs a peak current energization end signal when the integral value of 1 reaches a predetermined level L1.
2a, and a one-shot multivibrator (hereinafter referred to as one-shot MV) 12 which outputs a pulse having a predetermined pulse intensity Tm upon receiving a peak current energization period end signal.
It has b. The current integration circuit 11 is configured to have its integration level reset and return to zero level upon receiving the peak current energization end signal output from the one-shot MV 12b.

The energization period control means 2 has a welding voltage error amplification circuit 20 and a V
Since the /F conversion circuit 21 is the same as that in FIG. 1, the same reference numerals are given and the explanation thereof will be omitted. Analog switch 5W20
is the attenuator circuit A until the arc occurs.
This is to prohibit the welding voltage E transmitted via the TT from being applied to the welding voltage error amplification circuit 20, and the no-load voltage (higher than the welding voltage after the arc occurs) until the arc occurs causes V/ The cycle (energization cycle) of the peak current energization start signal output from the F conversion circuit 21 is prevented from becoming long, and the energization cycle T is minimized to promote arc expansion.

The current control means 5 includes a welding current setting section 50 that sets a welding average current reference value 1r, a peak current setting section 51 that sets a peak current reference value rpr, and a base current reference value 1br.
and analog switches 5W50 and 5WI51 that select the reference level set by each of these setting sections according to the peak current energization signal or the base current energization signal output from the energization switching section 3.
, a peak current reference value Tpr or a base current reference value 1br, and a welding current error amplification circuit 53 that outputs an error in the welding current output from the welding current amplification circuit AMP. Note that the peak current setting section 51 is designed to work in conjunction with the welding current setting section 50, and the peak current reference W
Even when I I p r is set to the minimum value, it is prevented from becoming a value lower than the welding average current reference value 1r. Further, the welding average current reference value Tr set by the welding current setting section 50 is output to the wire feeding control section 8, and
The welding wire is fed at a speed proportional to the welding average current reference value Ir.

The error signal output from the welding current error amplification circuit g853 of the current control means 5 is the PW M l! of the pulse radiation control section 7.
A pulse radiation control signal corresponding to the error signal is transmitted to the Fl ij circuit 71 and is transmitted to the inverter I through the drive circuit 70.
It is transmitted to the NV to change the duty of the switching voltage, thereby performing feedback control so that the welding current I (peak current 1p and base current 1b) always matches the set level of the current control means 5. .

The starting control unit 6 controls the start control unit 6 for a predetermined time t1 after the arc is generated.
The starting current reference signal Is is sent to the error amplification circuit 53 of the current control means 5, and the analog switch 5W2 of the energization cycle control means 2 is sent to the error amplifier circuit 53 of the current control means 5 during the period until an arc occurs.
Performs an operation to open 0.

Next, the operation of the pulse arc welding apparatus having such a configuration will be explained with reference to the waveform charts shown in FIGS. 10(a) to 10(m).

In addition, corresponding symbols (a) to (m) are attached to FIG. 9.

1. Operation at the start of welding.

■When the torch switch (not shown) is operated, a no-load voltage is applied between the welding wire W and the base metal M. ■The period from the application of the no-load voltage until the generation of an arc is Since the analog switch 5W20 of the energization cycle control means 2 is open, the welding voltage E (no-load voltage) is not inputted to the welding voltage error amplification circuit 20. Therefore, the welding voltage error amplification circuit 20 outputs the welding average voltage reference. An error signal corresponding to the value Er is input to the V/F conversion circuit 21, and the V/F conversion circuit 21 outputs a peak current energization start signal so as to minimize the energization period T in order to increase the welding average voltage.

■When the welding wire W contacts the base metal M, an arc is generated,
During the period from when the arc occurs until a predetermined time t1 has elapsed, the starting current reference signal ■S is sent from the starting control section 6 to the error amplifying circuit 53 of the current control means 5 to increase the welding current ■ to the maximum value. control and promote increase in arc length. Note that the output of the energization signal from the energization switching section 30 is cut off by the activation control section 6 until the time tl has elapsed.

(2) On the other hand, in the peak current energization period control section 1, the current integration operation is not performed because the energization signal is not output from the energization switching section 3 until time t1 has elapsed. However, time t
When 1 elapses, the flow reference signal Is stops the activation output from the activation control section 6 to the current control means 5, and
A peak current energization signal is held and output from the energization switching section 3 . This closes the analog switch 5WIO,
The welding current I detected by the welding current amplifier circuit AMP is processed in the calculation circuit 10 (calculation of raising the welding current I to the A power), and the processed signal is integrated in the current integration circuit 11.

■When the integral value of the current integration circuit 11 reaches a predetermined level L1 determined in advance by the comparator 12a of the integral level determination unit 12, a peak current energization end signal is output to the one-shot MV 12b, and the one-shot MV 12b receives this peak current energization. Upon receiving the end signal, a signal with a predetermined pulse width tm is output to the energization switching section 3, and the current integration circuit 11 is reset (the pulse width tm is set to the time required to reset the current integration circuit 11). ).

■The energization switching unit 3 receives the peak current energization end signal output from the one-shot MY 12 b, holds and outputs the base current energization signal, thereby opening the analog switch 5WIO, and also opens the analog switch 5WIO of the welding current control means 5. The switch SW51 is closed to switch the welding current (2) to the base current 1b.

■On the other hand, until an arc occurs, the energization cycle control means 2
In this case, the analog switch 5W20 remains open due to the control signal output from the start-up control section 6, and is used for energization)
[l] Since T is controlled to the minimum and the peak current energization start signal is continuously input manually from the energization cycle control means 2 in the energization switching unit 3, one shot of the energization cycle control means 1)
At the same time as the peak current energization period end signal of pulse width tm output from V12b stops, the peak current energization period tp returns again.

In this manner, in the initial stage of welding, the analog switch 5W20 of the energization cycle control means 2 is opened by the start control unit 6 until an arc is generated, thereby shortening the energization cycle T to prevent melting of the welding wire and arc. Controls are in place to promote length increases.

2. Next, the operation in a steady welding state will be explained.

■After the arc occurs, the analog switch 5W20 of the energization cycle control means 2 is closed by the start control section 6,
Welding voltage error amplification circuit 20 compares welding voltage E transmitted via attenuator circuit ATT with welding average voltage reference level Er set by welding voltage reference setting section 4 and outputs an error signal. Then, the V/F conversion circuit 21 outputs a peak current energization start signal to the energization switching section 3 at the energization period TI8 corresponding to the error signal level, and the energization switching section 3 holds and outputs the peak current energization signal.

■The peak current energization period control means 1 receives the peak current energization signal output from the energization switching section 3, closes the analog switch 5WIO, and calculates the welding current I
(peak current 1p) is integrated by the current integration circuit 11, and when the integrated value reaches a predetermined level L1, the integral level determination section 12 outputs a peak current energization end signal to the energization switching section 3, and outputs the base current energization signal while holding it. do.

■ By repeating the above operation ■■, the base current energization signal and the peak current energization signal are alternately switched and output from the energization switching section 3, and the current control means 5 receives this switching signal and outputs the base current energization signal and the peak current energization signal. The analog switches 5W51 and 50 are alternately closed to control the base current Ib and the peak current 1p.

In this way, in the welding device that implements the pulsed arc welding method of the first invention, when the peak current 1p is variably set,
Since the peak current energization period tp is automatically controlled based on the amount of energy energized to the welding wire by the peak current 1p, the peak current 1p can be energized for the optimum time required for one pulse and one droplet transfer, and, Welding average voltage Ea
It is possible to perform welding with a reduced amount of spatter even when the droplet is low and a short circuit occurs during droplet detachment.

FIG. 11 shows a specific circuit example of a pulse arc welding apparatus implementing the first invention, and parts corresponding to those in FIG. 9 are given corresponding symbols.

In the figure, the arithmetic circuit 10 of the peak current energization period control means 1 is configured by connecting a square arithmetic circuit 10a and an inverting amplifier circuit 10b in parallel.
Arithmetic processing is performed to raise the value to the A power. The current integration circuit 11 is configured by an integration circuit using an operational amplifier 11b, and upon receiving the peak current energization end signal transmitted from the one-shot MV 12b, closes the analog switch lla and forcibly removes the charge from the capacitor llc. It is designed to discharge (reset operation).

The welding voltage error amplification circuit 20 of the energization period control means 2 applies a welding voltage E attenuated by an attenuator circuit ATT to the inverting input terminal side of an error amplifier 20a using an operational amplifier, while applying the welding voltage E attenuated by the attenuator circuit ATT to the non-inverting input terminal side. By adding the welding average voltage reference value Er set in the voltage setting section 4, if the welding voltage E increases, the output error signal level decreases, and conversely, if the welding voltage E decreases, the output error signal level decreases. This output scissor difference signal is set to V/F.
In addition to the conversion circuit 21, a peak current energization start signal is outputted every cycle corresponding to the error signal. The energization switching section 3 includes a NAND gate 3a, an RS flip-flop 3b, and a NOT gate 3c.

3d and AND gate 3e are combined, and when the peak current energization end signal is applied to the reset terminal R, it has priority over the peak current energization start signal applied to the NAND gate 3a via the NOT gate 3c. In response to the peak current energization end signal, the base current energization signal is output. Note that the NOT gate 3d and the AND gate 3e are designed to inhibit the output of the peak current energization signal in response to a control signal from the activation control section 6 for a period from the occurrence of an arc until the elapse of a predetermined time t1. be.

FIG. 12 is a block diagram showing a configuration example of a pulse arc welding device implementing the second invention described above, and shows a welding device implementing the welding method of the first invention shown in FIG. In the peak current energization period control means 1'
The configuration shown in FIG. 3 is replaced with the configuration shown in FIG. 3, and since the operation is the same, the explanation will be omitted.

Figures 13 (a) to (m) show the waveforms of each part in Figure 12, and the corresponding parts in Figure 12 correspond to (a).
.about.(m) will be given and the explanation will be omitted.

No. 1411. t shows a detailed circuit example of the welding device shown in FIG. 12 for carrying out the second invention.

In the figure, the arithmetic circuit 10' of the peak current energization period control means 1° includes a square arithmetic circuit 1°a and an inverting amplifier circuit 10b.
and U analog switches 10c and 10d,
During the period when the energization switching unit 3 is receiving the base current energization signal, the analog switch 10c is closed and the welding current is changed to B.
During the period when the energization switching section 3 is receiving the peak current energization signal, the analog switch 10d is closed and the arithmetic processing is performed to raise the welding current 1 to the A power.

Further, the energization switching section 3 includes a NAND gate 3a, an RS flip-flop 3b, and a NAND gate 3a.

In this configuration example, the peak current energization signal is not inhibited by the control signal from the activation control section 6. Regarding other parts,
Since the configuration is the same as that shown in FIG. 11, the same reference numerals are given and the explanation will be omitted.

FIG. 15 shows the steps shown in FIG. 9 and 1 for carrying out the first invention.
In the welding device shown in FIG. 1 or the welding device shown in FIGS. 12 and 13 for carrying out the second invention,
This shows a configuration example in which the peak current energization period control means 1 (1'), the energization period control means 2, the energization switching section 3, and the activation control section 6 are replaced with a signal processing section 9 consisting of a CPU. Connected to the unit 9 are a ROM 9a that stores processing programs, data, etc., and a RAM 9b that temporarily stores processing data and the like.

In the welding apparatus having such a configuration, the arithmetic processing, integration processing, and integral level determination processing performed by the peak current energization period control means 1 (1') are concentrated in the signal processing section 9 according to a program stored in the ROM 9a. In addition, the welding voltage error amplification processing and V/F conversion processing that were performed by the energization cycle control means 2 are also performed centrally in the signal processing section 9, reducing the number of parts. In addition, it is possible to easily change the processing content simply by modifying the program stored in the ROM 9a, which facilitates design and improves reliability.

In addition, in the figure, peak current energization period control means 1 (1'),
Although the signal processing section 9 is configured to perform the functions of the energization cycle control means 2 and the U activation control section 60, it is also possible to have a configuration where the signal processing section 9 performs other functions in a concentrated manner.

[Effects of the Invention] According to the present invention as set forth in claim 1, since the peak current can be varied, fine control can be performed according to the welding conditions. In addition, the amount of energy applied to the welding wire due to peak current application is equivalently determined, and based on this, the optimal peak current application period for one pulse and one droplet transfer is automatically controlled. Even if the welding current waveform becomes dull due to a drop in the lt source voltage or an increase in the length of the secondary cable, the amount of energy supplied to the welding wire is controlled to be constant, making it possible to perform stable welding. Become. Furthermore, when the peak current is set low, the arc sound becomes softer, reducing the burden on the operator, and even when the average welding voltage is low and a short circuit occurs when a droplet detaches, a pulse that can reduce the amount of spatter is generated. Can provide arc welding method.

According to the present invention set forth in claim 2, the amount of energy applied to the welding wire due to the application of the peak current and the base current is equivalently determined, and the peak current application period is thereby automatically controlled. In addition to the effect described in item 1, it is possible to provide a pulsed arc welding method that allows for more fine-grained control that also takes into account the energy of the base current.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of main parts of a welding apparatus for carrying out the pulse arc welding method according to claim 1, Figs. FIG. 4 is a configuration diagram of the main parts of a welding device that implements the described pulse arc welding method (
, a) to (i) are waveform diagrams of each part, Figure 6 is a graph showing the minimum value of the peak current energization period required for one pulse and one droplet transfer, Figure 6 is a graph showing droplet detachment with respect to welding current Figures 7(a) and (b) are explanatory diagrams showing the change in droplet transfer opening due to changes in peak current, and Figures 8(a) and (b) are diagrams showing the progress of droplet transfer. FIG. 9 is an explanatory diagram showing changes in the peak current energization period due to changes in the base current, and FIG. )~
(m) is a waveform diagram of each part, FIG. 11 is a detailed circuit example diagram, FIG. 12 is a block configuration example diagram of a welding apparatus for carrying out the welding method of the present invention according to claim 2, and FIG. 13 (a)
~(m) is a waveform diagram of each part, FIG. 14 is a detailed circuit example diagram, and FIG. FIG. [Explanation of symbols] 1.1' ... Peak current energization period control means 10゜1 l ・ 12 ・ 2 ・ φ 20 φ 21 ・ 3 ・ φ 4 Fist ・ E ・ ・ Er ・ I C ・ Ip ・ Ib number tb ・ tp ・ M −Φ W ・ ・ 10'... Arithmetic circuit...Current integration circuit...Integral level determination section/Electrification cycle control means...Welding voltage error amplification circuit...V/F conversion circuit/Electrification switching Welding voltage setting section Welding voltage Welding average voltage reference value Critical current Peak current Base current Base current energization period Peak current energization period Welding base material Welding wire

Claims (2)

[Claims] (1) In a pulsed arc welding method in which a peak current exceeding the critical current level and a base current lower than the critical current level are alternately applied between the welding wire and the welding base metal, the welding average voltage is a predetermined value. While controlling the energization cycle so that peak current is applied, the detected welding current is subjected to predetermined calculation processing and then integrated, and when this integration level reaches a predetermined level, peak current is applied. 1. A pulse arc welding method characterized in that the peak current energization period is automatically controlled by stopping the energization and switching to base current energization, thereby automatically controlling the peak current energization period. (2) In a pulsed arc welding method in which a peak current exceeding the critical current level and a base current lower than the critical current level are alternately applied between the welding wire and the welding base metal, the welding average voltage is a predetermined value. While controlling the energization cycle so that when the base current is energized, the detected welding current is subjected to predetermined calculation processing and then integrated, and when the subsequent peak current is energized, the detected welding current is subjected to the above calculation processing when the base current is energized. is integrated after performing different predetermined arithmetic processing, and when the sum of these integral levels reaches a predetermined level, the peak current is stopped and switched to the base current, thereby reducing the peak current. A pulse arc welding method characterized in that the period is automatically controlled.