WO2022209432A1 - Welding control method, welding power supply, welding system, welding method, and additive manufacturing method - Google Patents

Abstract

The present invention suppresses the phenomenon of a disturbance in the regularity of droplet transfer, and reduces sputter. This welding control method, which controls a pulse waveform having one cycle formed of a first pulse period (T1) and a second pulse period (T2) , has: a voltage detection step for outputting, by a voltage detection means (VD), a voltage detection signal (Vo); a voltage deviation average calculation step for calculating, by a voltage deviation average calculation means (81), a voltage deviation average value (Verrp2_ave) in a predetermined section in the second pulse period (T2), on the basis of a difference signal, which is a difference between the voltage detection signal (Vo) and a predetermined set voltage (Vs); and a control amount calculation step for calculating, by a control amount calculation means (82), a control amount for at least one of a first peak current value (Ip1) and a second peak current value (Ip2), on the basis of the voltage deviation average value (Verrp2_ave).

Description

Welding control method, welding power source, welding system, welding method and additive manufacturing method

The present invention relates to a welding control method, a welding power source, a welding system, a welding method, and an additive manufacturing method applying gas shielded arc welding in gas shielded arc welding using a pulse waveform.

In gas-shielded metal arc welding (GMAW), if the shielding gas contains a component with a high potential gradient such as carbon dioxide gas, nitrogen gas, hydrogen gas, or oxygen gas, the form of droplet transfer is globular. take a transition. In globular transfer, since the size of droplets transferred to the molten pool becomes irregular, there has been a problem in welding workability, mainly due to the generation of spatter. As an application example of this GMAW, there is "additive manufacturing" technology, more specifically metal additive manufacturing (WAAM: Wire and Arc Additive Manufacturing) technology, and this problem is not limited to the field of welding, It is also a common challenge in the field of additive manufacturing.
Note that the term additive manufacturing is sometimes used in a broad sense as the term “laminate manufacturing” or “rapid prototyping”, and in the present invention, the term “laminate manufacturing” is used uniformly. Further, when the welding technique of the present invention is applied to additive manufacturing, the term "welding" may be appropriately replaced with "welding", "additive manufacturing", "additive manufacturing", or the like. For example, when it is treated as welding, it is "welding control method" or "welding power source", but when it is treated as layered manufacturing, it is rephrased as "layered manufacturing control method" or "layered manufacturing power source".

In order to solve the above problems, in Patent Document 1, in consumable electrode arc welding using carbon dioxide alone or a mixed gas containing carbon dioxide as a main component, the welding arc is stabilized and the droplet transfer regularity is improved. A technique is disclosed for significantly reducing the amount of spatters and fumes generated.
Specifically, the technique is a method of arc welding using a pulse current in which a first pulse and a second pulse having pulse waveforms with different pulse peak current levels and pulse widths are alternately repeated as a welding current, The peak current of the first pulse is 300-700A, the peak period is 0.3-5.0ms, the base current is 30-200A, the base period is 0.3-10ms, and the peak current of the second pulse is 200-600A. , a peak period of 1.0 to 15 ms, a base current of 30 to 200 A, and a base period of 3.0 to 20 ms. According to this method, the stability of the welding arc can be improved, and the amount of large spatter and fume generated can be greatly reduced. It is said that the spatter caused by the scattering of the melt remaining on the wire can be greatly reduced.

Further, in Patent Document 2, even if a carbon dioxide-based shield gas is used, one droplet transfer is possible per cycle. A technique that can be restored is disclosed.
Specifically, in this technique, when the regularity of droplet transfer is disturbed by some disturbance, following the first pulse for detaching the droplet, a third pulse different from the second pulse for shaping the droplet is applied. This is a method of outputting, which shortens the time required to restore the regularity of droplet transfer to a normal state, compared to the conventional method. According to this method, it is possible to reduce the spatter and fume generated during the period required to restore the normal state, and as a result, even if the regularity of the droplet transfer is disturbed, the deterioration of the welding quality at that time is minimized. It is said that it is possible to stop it.

Japanese Patent Application Laid-Open No. 2007-237270 Japanese Patent Application Laid-Open No. 2009-233728

However, as pointed out in paragraph 0017 of Patent Document 2, in the technique of Patent Document 1, droplet transfer occurs due to some disturbance with respect to the waveform set to alternately generate the first pulse and the second pulse. When this regularity is disturbed, spatters and fumes are generated until the normal state is restored. Further, the technique of Patent Document 2 is a waveform that is set to alternately generate a first pulse and a second pulse when the regularity of droplet transfer is disturbed. By outputting 3 pulses, it is reset so as to return to a normal state, but this 3rd pulse causes the generation of spatter. Therefore, in order to significantly reduce the spatter, it is necessary to suppress the phenomenon that the regularity of droplet transfer is disturbed.

The present invention has been made in view of the above-described problems, and its object is to provide a first pulse period for detaching a droplet and a sufficient size of a droplet to form on the tip of a welding wire. Welding control method, welding power source, welding system, and welding method capable of suppressing a phenomenon in which the regularity of droplet transfer is disturbed and reducing spatter for a waveform set to alternately generate a second pulse period and to provide a layered manufacturing method.

Therefore, the above object of the present invention is achieved by the following configuration [1] relating to the welding control method.
[1] A welding control method for controlling the waveform of a welding current in gas shielded arc welding, comprising:
The waveform of the welding current is a pulse waveform in which one cycle is a first pulse period for detaching a droplet and a second pulse period for forming a sufficiently large droplet at the tip of the welding wire. and
The first pulse period is composed of a predetermined first peak period having a first peak current value and a first base period after the first peak period,
The second pulse period is composed of a predetermined second peak period having a second peak current value lower than the first peak current value, and a second base period after the second peak period,
a voltage detection step of outputting a voltage detection signal Vo;
When the difference between the voltage detection signal Vo and the predetermined set voltage Vs is used as the difference signal, a voltage deviation average value Verrp2_ave in a predetermined section within the second pulse period is calculated based on the difference signal. a voltage deviation average calculation step;
and a controlled variable calculation step of calculating a controlled variable for at least one of the first peak current value and the second peak current value based on the voltage deviation average value Verrp2_ave.

Further, the above object of the present invention is achieved by the following configuration [2] relating to a welding power source.
[2] A welding power source for performing waveform control of welding current in gas shielded arc welding,
The waveform of the welding current is a pulse waveform in which one cycle is a first pulse period for detaching a droplet and a second pulse period for forming a sufficiently large droplet at the tip of the welding wire. and
The first pulse period is composed of a predetermined first peak period having a first peak current value and a first base period after the first peak period,
The second pulse period is composed of a predetermined second peak period having a second peak current value lower than the first peak current value, and a second base period after the second peak period,
voltage detection means for outputting a voltage detection signal Vo;
When the difference between the voltage detection signal Vo and the predetermined set voltage Vs is used as the difference signal, a voltage deviation average value Verrp2_ave in a predetermined section within the second pulse period is calculated based on the difference signal. voltage deviation average calculation means;
and control amount calculation means for calculating a control amount for at least one of the first peak current value and the second peak current value based on the voltage deviation average value Verrp2_ave.

Further, the above object of the present invention is achieved by the configuration [3] below relating to the welding system.
[3] A welding system comprising at least a welding robot, a feeding device, a welding power source, a shielding gas supply device, and a welding control device, and used for waveform control of welding current in gas-shielded arc welding,
The waveform of the welding current is a pulse waveform in which one cycle is a first pulse period for detaching a droplet and a second pulse period for forming a sufficiently large droplet at the tip of the welding wire. and
The first pulse period is composed of a predetermined first peak period having a first peak current value and a first base period after the first peak period,
The second pulse period is composed of a predetermined second peak period having a second peak current value lower than the first peak current value, and a second base period after the second peak period,
The welding power source is
voltage detection means for outputting a voltage detection signal Vo;
When the difference between the voltage detection signal Vo and the predetermined set voltage Vs is used as the difference signal, a voltage deviation average value Verrp2_ave in a predetermined section within the second pulse period is calculated based on the difference signal. voltage deviation average calculation means;
and control amount calculation means for calculating a control amount for at least one of the first peak current value and the second peak current value based on the voltage deviation average value Verrp2_ave.

Further, the above object of the present invention is achieved by the following configuration [4] relating to the welding method.
[4] A welding method for arc welding while controlling the waveform of the welding current in gas shielded arc welding,
At least one of carbon dioxide gas, nitrogen gas, hydrogen gas and oxygen gas is included as the shielding gas used for arc welding,
The waveform of the welding current is a pulse waveform in which one cycle is a first pulse period for detaching a droplet and a second pulse period for forming a sufficiently large droplet at the tip of the welding wire. and
The first pulse period is composed of a predetermined first peak period having a first peak current value and a first base period after the first peak period,
The second pulse period is composed of a predetermined second peak period having a second peak current value lower than the first peak current value, and a second base period after the second peak period,
As the waveform control method,
a voltage detection step of outputting a voltage detection signal Vo;
When the difference between the voltage detection signal Vo and the predetermined set voltage Vs is used as the difference signal, a voltage deviation average value Verrp2_ave in a predetermined section within the second pulse period is calculated based on the difference signal. a voltage deviation average calculation step;
and a controlled variable calculation step of calculating a controlled variable for at least one of the first peak current value and the second peak current value based on the voltage deviation average value Verrp2_ave.

In addition, the above object of the present invention is achieved by the following configuration [5] related to the layered manufacturing method.
[5] A layered manufacturing method for performing layered manufacturing while controlling the waveform of a welding current in layered manufacturing applying gas shielded arc welding,
At least one gas selected from carbon dioxide gas, nitrogen gas, hydrogen gas, and oxygen gas is included as the shielding gas used in the gas-shielded arc welding,
The waveform of the welding current is a pulse waveform in which one cycle is a first pulse period for detaching a droplet and a second pulse period for forming a sufficiently large droplet at the tip of the welding wire. and
The first pulse period is composed of a predetermined first peak period having a first peak current value and a first base period after the first peak period,
The second pulse period is composed of a predetermined second peak period having a second peak current value lower than the first peak current value, and a second base period after the second peak period,
As the waveform control method,
a voltage detection step of outputting a voltage detection signal Vo;
When the difference between the voltage detection signal Vo and the predetermined set voltage Vs is used as the difference signal, a voltage deviation average value Verrp2_ave in a predetermined section within the second pulse period is calculated based on the difference signal. a voltage deviation average calculation step;
and a controlled variable calculation step of calculating a controlled variable for at least one of the first peak current value and the second peak current value based on the voltage deviation average value Verrp2_ave.

According to the present invention, the first pulse period for detaching a droplet and the second pulse period for forming a droplet of sufficient size on the tip of the welding wire are alternately generated. By controlling at least one of the first peak current value in the first pulse period and the second peak current value in the second pulse period with respect to the waveform, the phenomenon that the regularity of droplet transfer is disturbed can be suppressed. Occurrence can be further reduced.

FIG. 1 is a schematic diagram showing a configuration example of a welding system according to this embodiment. FIG. 2A is a graph showing a reference pulse waveform; FIG. 2B is an explanatory diagram of each set value in the reference pulse waveform. FIG. 3 is a block diagram of the welding power source. FIG. 4 is an enlarged view of the main part of the block diagram shown in FIG. The upper graph in FIG. 5 is a graph showing a comparison between the voltage detection signal Vo and the voltage setting signal Vs in the second pulse period T2. The lower graph in FIG. 5 is a graph showing the integrated difference between the voltage detection signal Vo and the voltage setting signal V in the second pulse period T2. FIG. 6 is a graph showing an example of changes in the falling portion of the first peak current value Ip1. FIG. 7 is a graph showing a state in which predetermined fixed waveform control is added during the first base period Tb1 when no detachment detection signal is detected. In FIG. 8, when the detachment detection signal is not detected during fixed waveform control, a predetermined fixed value Ic1 is set to a predetermined second peak current reference value Ip2_ref as the second peak current value Ip2 for the next pulse period. FIG. 10 is a graph showing the application of subtracted current values; FIG. FIG. 9 is a graph showing an example of each control method when a short-circuit signal is detected during the first pulse period T1 and when arc instability is detected during the second pulse period T2.

An embodiment according to the present invention will be described below with reference to the drawings. Note that this embodiment is an example in which a welding robot is used, and the welding control method according to the present invention is not limited to the configuration of this embodiment. For example, the welding control method of the present invention may be applied to an automatic welding device using a cart, or the welding control method of the present invention may be applied to a small portable welding robot. Moreover, in this embodiment, a gas-shielded arc welding method using a pulse waveform is used.
Furthermore, in this embodiment, a gas-shielded arc welding method to which the welding control method according to the present invention is applied will be described. Applicable.

<Overview of arc welding system>
First, the outline of the arc welding system used in the welding control method of this embodiment will be described. FIG. 1 is a schematic diagram showing a configuration example of an arc welding system according to this embodiment. The arc welding system 10 includes a welding robot 20, a welding power source 30, a controller 40, a controller 50, a feeder (not shown), and a shield gas supply (not shown).

The welding power source 30 is connected to the welding robot 20 via a positive power cable (not shown) so as to energize the welding wire 22, which is a consumable electrode, and is connected to the welding robot 20 via a negative power cable (not shown). (hereinafter also referred to as "work") is connected to W. The connection state shown in FIG. 1 is for welding with reversed polarity. When welding with positive polarity, the polarity of the welding power source 30 may be reversed.

Also, the welding power source 30 and a feeding device for feeding the welding wire 22 are connected by a signal line (not shown), and the feeding speed of the welding wire 22 can be controlled.

The welding robot 20 has a welding torch 21 as an end effector. The welding torch 21 has an energizing mechanism for energizing the welding wire 22, that is, a contact tip (not shown). When the welding wire 22 is energized from the contact tip, an arc is generated from the tip of the welding wire 22, and the heat from the welding wire 22 welds the workpiece W to be welded.

Furthermore, the welding torch 21 is provided with a shield gas nozzle (not shown), which is a mechanism for ejecting shield gas. The shielding gas may have a gas composition that takes the form of globule migration due to the characteristics of the waveform used in this embodiment. Specifically, at least one of carbon dioxide gas, nitrogen gas, hydrogen gas, and oxygen gas, which has a high potential gradient, is preferably included. In addition, from the viewpoint of versatility, it is more preferable to use carbon dioxide alone, and in the case of a mixed gas with argon gas (hereinafter also referred to as “Ar”), among carbon dioxide, nitrogen gas, hydrogen gas and oxygen gas A system containing at least one gas and containing a total of 5 to 50% of a gas other than Ar is more preferable. Shield gas is supplied from a shield gas supply device.

The welding wire 22 used in this embodiment may be either a solid wire containing no flux or a flux-cored wire containing flux. The welding wire 22 may be made of any material, such as mild steel, stainless steel, aluminum, or titanium, and the wire surface may be plated with copper or the like. Furthermore, the diameter of the welding wire 22 is not particularly limited. In this embodiment, the upper limit of the diameter is preferably 1.6 mm and the lower limit of the diameter is 0.8 mm.

In addition, the work W in this embodiment is not particularly limited, and joint shape, welding posture, groove shape, etc. are not particularly limited.

The control device 40 mainly controls the operation of the welding robot 20. The control device 40 holds teaching data in which the operation pattern of the welding robot 20, the welding start position, the welding end position, the welding conditions, the weaving operation, etc. are defined in advance. controls the behavior of In addition, the control device 40 provides the welding power source 30 with welding conditions such as welding current, arc voltage, and feed speed during the welding operation according to the teaching data.

The controller 50 is connected to the control device 40 , creates or displays a program for operating the welding robot 20 , inputs teaching data, etc., and provides it to the control device 40 . It also has a function of manually operating the welding robot 20 . It does not matter whether the connection between the controller 50 and the control device 40 is wired or wireless.

The welding power source 30 generates an arc between the welding wire 22 and the work W by supplying power to the welding wire 22 and the work W according to a command from the control device 40 . Welding power supply 30 also outputs a signal for controlling the speed at which welding wire 22 is fed to the feeding device in accordance with a command from control device 40 .

<Reference pulse waveform>
Next, the pulse waveform of the welding current output from welding power source 30 will be described. In this embodiment, as shown in FIG. 2A, the pulse waveform of the welding current output from the welding power source 30 has a first pulse period T1 for detaching the droplets and a sufficiently large pulse waveform at the tip of the welding wire. A waveform set to alternately generate a second pulse period T2 for forming droplets (hereinafter also referred to as a “reference pulse waveform”) is used as a reference.

The first pulse period T1 has a first peak period Tp1 having a predetermined first peak current value Ip1, a first base current value Ib1 predetermined, and a first base period Tb1 after the first peak period Tp1. consists of Further, the second pulse period T2 has a second peak period Tp2 having a second peak current value Ip2 lower than the predetermined first peak current value Ip1 and a predetermined second base current value Ib2. It is composed of a second base period Tb2 after two peak periods Tp2.
Note that the first peak period Tp1 and the second peak period Tp2 each include a rising portion and a falling portion. That is, each of the first peak period Tp1 and the second peak period Tp2 is composed of a rising portion, a peak portion, and a falling portion. Furthermore, in this embodiment, one period of the reference pulse waveform is composed of the first pulse period T1 and the second pulse period T2.

When welding is performed under such pulse conditions, droplets 23 and 24 grow at the tip of the welding wire 22 during the second peak period Tp2, as shown in FIG. 2A. Since the current abruptly decreases in the second base period Tb2, the pushing-up force is weakened, and the droplet 25 is shaped so as to hang down at the tip of the welding wire 22. As shown in FIG. Next, when entering the first peak period Tp1, the droplets 26 and 27 form a constriction and rapidly detach due to the influence of the electromagnetic pinch force due to the first peak current set high. At the moment when the arc moves toward the welding wire 22 after the separation, the current is lowered during the first base period Tb1. As a result, small spatter due to scattering of the constricted portion of the welding wire 22 and scattering of residual melt after separation is reduced. Thereafter, similarly, droplet transfer is performed in which droplets are repeatedly formed and detached.

<Functional configuration of welding power source>
Next, the functional configuration of the welding power source 30 according to this embodiment will be described in detail. As shown in FIG. 3, the welding power source 30 includes a power supply unit PM that supplies electric power for generating an arc and performing welding, a correction amount calculation circuit 60 that calculates various correction amounts such as the correction current Ierr, An output current control circuit 70 that receives signals such as a feed speed command, a welding current command, and an arc voltage command and outputs a current setting signal Ir, and a correction current Ierr and a current setting signal Ir that receive the control amount of the power supply unit PM. a voltage detection unit VD that detects the arc voltage during welding and outputs a voltage detection signal Vo; and a welding current during welding that detects the welding current detection signal Io. It has a current detection section ID for output and a pulse waveform correction circuit 80 for correcting a set value related to the pulse waveform.

The power supply unit PM receives a commercial power supply such as a three-phase 200V power supply, converts the input AC voltage into a current error amplification signal Ei which is an error amplification signal between a control output current setting signal Iset and a welding current detection signal Io, which will be described later. Accordingly, the output is controlled by an inverter, an inverter transformer, a rectifier, etc. (not shown) to output the welding current and the arc voltage. Also, a reactor WL is configured to smooth the output voltage.

The current detector ID detects the welding current during welding and outputs the welding current detection signal Io. The welding current detection signal Io is digitally converted by an A/D converter (not shown) and input to the current error amplifier circuit EI, the output current control circuit 70, the correction amount calculation circuit 60 and other control circuits. The current error amplification circuit EI inputs the current error amplification signal Ei to the power supply unit PM. The power supply unit PM performs output control with an inverter, an inverter transformer, a rectifier, etc. according to the current error amplification signal Ei, and outputs welding current and arc voltage.

A voltage detection unit VD detects an arc voltage during welding and outputs a voltage detection signal Vo. The voltage detection signal Vo is digitally converted by an A/D converter (not shown) and input to a pulse waveform correction circuit 80, an output current control circuit 70, a correction amount calculation circuit 60, and other control circuits, which will be described later.

Here, the correction amount calculation circuit 60 is a general term for circuits that output various correction amounts. In the present embodiment, the type of correction amount calculation circuit is not particularly limited, and the circuit may be provided as necessary. Circuits that output various correction amounts include, for example, a short-circuit determination circuit, a short-circuit/arc determination circuit, an electronic reactor control circuit, and an external characteristic correction circuit. A correction current Ierr is output from these correction circuits and input to the addition circuit ADD.

The output current control circuit 70 includes a storage section DB and a pulse state generation section 71, and outputs the current setting signal Ir generated within the output current control circuit 70 to the addition circuit ADD. The storage unit DB stores data such as various initial setting signals, determinations, threshold values applied in each calculation unit, external characteristic coefficients of the welding power source 30, that is, output characteristics of the welding power source 30, and the like. output a signal to

For example, in the present embodiment, the storage unit DB stores in advance the welding current setting signal Is, the voltage setting signal Vs, the wire feed speed setting signal Wfr, or the set values for waveform control, constants for calculation by various circuits, and the like. is input directly, or input from the welding current setting circuit IS, the output voltage setting circuit VS, the wire feed speed setting circuit WFR, etc., and stored. In this embodiment, each set value is input to various circuits through the storage section DB, but these set values may be directly input to various circuits, and the storage section DB may be used as an output current control circuit. 70 may be provided independently.

Also, the waveform control setting values include, for example, the peak period, peak current, base period, base current, pulse period, etc. when performing pulse waveform control, and when performing waveform control during a short circuit, Examples include a set value for a control period, a set value for an inclination, and the like.
For example, in the present embodiment, as shown in FIG. 2B, a first peak current reference value Ip1_ref, a first base current reference value Ib1_ref, a first peak period reference value Tp1_ref, a first base period reference value Tb1_ref, a second peak Current reference value Ip2_ref, second base current reference value Ib2_ref, second peak period reference value Tp2_ref, second base period reference value Tb2_ref, first peak rising period reference value Tp1u_ref, first peak falling period reference value Tp1d_ref, second The peak rising period reference value Tp2u_ref, the second peak falling period reference value Tp2d_ref, and the like are used as waveform control set values.

The pulse state generator 71 in the output current control circuit 70 is used to control the pulse waveform of the welding current, as shown in this embodiment, and inputs set values related to various pulse waveforms from the storage unit DB. A correction signal output from the pulse waveform correction circuit 80 is input, and a current setting signal Ir having a pulse waveform is output.

The addition circuit ADD inputs the correction current Ierr output from the correction amount calculation circuit 60 . The addition circuit ADD adds the current setting signal Ir output from the output current control circuit 70 to the correction current Ierr, and outputs the control output current setting signal Iset to the current error amplifier circuit EI. The correction current Ierr may be input to the addition circuit ADD not only from the correction amount calculation circuit 60 but also from other control circuits (not shown).

<Functional configuration of pulse waveform correction circuit>
Next, the functional configuration of the pulse waveform correction circuit 80 according to this embodiment will be described in detail with reference to FIG. As shown in FIG. 4, the pulse waveform correction circuit 80 has a voltage deviation average calculator 81 as a voltage deviation average calculator and a pulse waveform control amount calculator 82 as a control amount calculator.
In this embodiment, a process for outputting the peak current correction command signal Ip2ref_set for the purpose of correcting the second peak current Ip2 to increase or decrease will be described. As in the present embodiment, the peak current correction command signal Ip2ref_set for the second peak current Ip2 may be used, or the peak current correction command signal Ip1ref_set for the first peak current value Ip1 may be used, or both may be calculated and output. good.

The voltage deviation average calculation unit 81 receives at least the voltage setting signal Vs and the voltage detection signal Vo, and calculates the voltage deviation average value Verrp2_ave necessary for calculating the peak current manipulated variable Di_sum in the pulse waveform control amount calculation unit 82. and output to the pulse waveform control amount calculator 82 .

An example of the calculation process of the voltage deviation average value Verrp2_ave in the voltage deviation average calculation unit 81 will be given below.

(a) The voltage deviation average calculator 81 inputs the voltage setting signal Vs and the voltage detection signal Vo, and calculates the difference value Verr between the voltage setting signal Vs and the voltage detection signal Vo for each predetermined detection sampling. . For example, if the sampling period is set to 0.05 msec (50 μsec), the difference value Verr is calculated every 0.05 msec.
(b) The voltage deviation average calculator 81 extracts at least one second pulse difference signal Verrp2, which is a difference signal for each sampling number in a predetermined interval within the second pulse period T2, for the difference value Verr. , the second pulse difference signal Verrp2 is integrated for the number of sampling times to calculate a voltage deviation integrated value Verrp2_sum. Specifically, as shown in FIG. 5, for example, the second pulse difference signal Verrp2 from the start of rising of the second peak period Tp2 to an arbitrary time within the second pulse period T2 is integrated by the sampling number.
Here, the difference described in (a) and (b) above is the difference between the voltage detection signal Vo as the actual measurement value and the set voltage (voltage setting signal) Vs as the reference value. It can also be said to be a deviation, and the difference signal may be rephrased as a voltage deviation signal.
In addition, in order to improve the accuracy of the voltage deviation average value Verrp2_ave, which will be described later, and to perform welding control more accurately, from the rise of the second peak period Tp2 to the end of the second base period Tb2, that is, the entire second pulse period T2 is preferably the sampling range.
(c) The voltage deviation average calculator 81 divides the calculated voltage deviation integrated value Verrp2_sum by the sampling number (referred to as “2ndcnt” in FIG. 4) counted by the second pulse period sampling counter (not shown). Then, the smoothed voltage deviation average value Verrp2_ave is calculated.

Subsequently, the pulse waveform control amount calculation unit 82 inputs the voltage deviation average value Verrp2_ave output from the voltage deviation average calculation unit 81 to the pulse waveform control amount calculation unit 82, which will be described in detail below. By calculating the peak current manipulated variable Di_sum, which is the correction amount, and adding the second peak current reference value Ip2_ref to the peak current manipulated variable Di_sum, the peak current correction command signal Ip2ref_set of the second peak current is generated by the pulse state generator 71. Enter to

An example of the calculation process of the peak current correction command signal Ip2ref_set of the second peak current Ip2 in the pulse waveform control amount calculation unit 82 will be given below.

(d) The pulse waveform control amount calculator 82 inputs the voltage deviation average value Verrp2_ave, and multiplies the voltage deviation average value Verrp2_ave by at least a predetermined gain value P2_gain and a current correction coefficient Ic_ave described later as a correction coefficient. and the current manipulated variable Di is calculated. In the present embodiment, the gain value P2_gain is stored in a database in the storage unit DB and is determined in advance, and is preferably set for each feeding speed or set welding current at least because an appropriate gain value can be set.
(e) The calculated current manipulated variable Di is integrated for each period (see "Integration ΣDi" in FIG. 4). For example, when the current manipulated variable Di calculated in the first cycle immediately after the start of welding is D1, the peak current manipulated variable Di_sum is calculated as D1, and the current manipulated variable Di calculated in the next cycle is D2. Then, the manipulated peak current Di_sum is calculated as D1+D2, and when the manipulated current Di calculated in the next cycle is D3, the manipulated peak current Di_sum is calculated as D1+D2+D3.
(f) If the calculated peak current manipulated variable Di_sum is within the predetermined manipulated variable limiter range, here within the controlled variable range of the second peak current value Ip2, the second peak current reference value Ip2_ref is added. Thereby, the peak current correction command signal Ip2ref_set of the second peak current Ip2 is input to the pulse state generator 71 .

As described above, based on the function of the pulse waveform correction circuit 80 according to the present embodiment, the first pulse period T1 for detaching a droplet and the formation of a sufficiently large droplet at the tip of the welding wire At least one of the first peak current value Ip1 in the first pulse period T1 and the second peak current value Ip2 in the second pulse period T2 for the waveform set to alternately generate the second pulse period T2 for By controlling , it is possible to prevent the regularity of droplet transfer from being disturbed, and to further reduce the occurrence of spatter.

When the peak current manipulated variable Di_sum is out of the limiter range, that is, when it exceeds or falls below the limiter range, for example, the excess amount of the manipulated variable exceeding the limiter is removed during the first peak period Tp1 and the first peak period Tp1. The correction amount may be compensated for different set values in the base period Tb1 and the second base period Tb2. For example, it is preferable to control at least one of the base time and base current in the second base period Tb2 and the base time and base current in the first base period Tb1. Further, when it is determined that the limiter has been exceeded, a predetermined value may be increased or decreased with respect to the first peak current value Ip1 or the first base period Tb1. Thus, even when the control amount of the second peak current value Ip2 is out of the control amount range, it is possible to suppress the regularity of droplet transfer from being disturbed.

By the way, in the present embodiment, an example using the current correction coefficient Ic_ave as the correction coefficient is given. This current correction coefficient Ic_ave is calculated by adding the welding current setting signal Is and the peak current manipulated variable Di_sum before the current cycle. By multiplying the voltage deviation average value Verrp2_ave by the current correction coefficient Ic_ave, it is possible to control the amount of change during increase or decrease. That is, when the second peak current Ip2 is increased in the next cycle, the value of the current correction coefficient Ic_ave is increased, so that the pulse in the next cycle is greatly increased. Further, when the second peak current Ip2 is decreased in the next period, the value of the current correction coefficient Ic_ave becomes smaller, so that the pulse in the next period is reduced.
In this way, by changing the amount of change when the second peak current Ip2 in the next cycle is increased and when it is decreased, the amount of welding wire 22 melted in the second pulse period T2 can be controlled more accurately. can. Thus, using the current correction coefficient Ic_ave as a correction coefficient is preferable from the viewpoint of control.

In this embodiment, the control is performed as described above. However, as a simple method, for example, it is determined whether the peak current manipulated variable Di_sum is positive or negative, and a predetermined value is used as a correction coefficient to control the voltage. The deviation average value Verrp2_ave may be multiplied.

In addition, in the present embodiment, the slopes of the rising portion Tu and the trailing portion Td in at least one of the first peak period Tp1 and the second peak period Tp2 are changed in multiple steps, so that the melting Disturbance of the regularity of droplet migration can be suppressed more effectively.

FIG. 6 shows an example in which the slope of the falling portion Td is changed in multiple stages when the first peak period Tp1 consists of the rising portion Tu, the peak portion Tp, and the falling portion Td. The falling portion Td shown in FIG. 6 is an example in which the slope changes in three stages: a first slope section Td1 having an exponential curve with a slope, a holding section Tdc in which a predetermined current value is maintained, and a It is composed of a second slope section Td2 that drops to the first base current value Ib1 instantaneously.

By changing the slope of the falling portion Td of the first peak period Tp1 in multiple stages as shown in FIG. 6, it becomes easier to grasp the detachment detection signal in the first pulse period T1. If the detachment detection signal is overlooked and special control is interrupted to restore the regularity of droplet transfer despite the state of healthy droplet transfer, this will cause the regularity of droplet transfer to If the detachment detection signal can be reliably grasped as described above, it is possible to more effectively suppress the disturbance of the regularity of droplet transfer. Note that it is preferable to set the multi-step change of the slope in the falling portion Td or the rising portion Tu to three steps or less in terms of ease of control, that is, control efficiency, and the degree of effect of multi-step.

Next, even if it is possible to suppress the disturbance of the regularity of droplet transfer by the welding control method of the present embodiment, if the regularity of droplet transfer is disturbed, the regularity of droplet transfer is restored. A means for doing so will be described with reference to FIG. FIG. 7 is a graph showing a state in which the third pulse, which is predetermined fixed waveform control, is added when the detachment detection signal is not detected at the trailing edge Td of the first peak period Tp1.

In the present embodiment, it is preferable to determine whether or not the regularity of droplet transfer has been disturbed by detecting or not detecting the detachment detection signal within the first pulse period T1. If the detachment detection signal is not detected within the first pulse period T1, it is determined that the regularity of droplet transfer is disturbed, and an arbitrarily set period is set between the first pulse period T1 and the second pulse period T2. As fixed waveform control, a third pulse period T3 is inserted. After the insertion of the third pulse period T3, the transition to the second pulse period T2 may be performed without a detachment detection signal, or the third pulse period T3 may be continuously inserted until the detachment detection signal is detected. good. Note that the third pulse period T3 of the present embodiment has a waveform including a third peak period Tp3 and a third base period Tb3. The third peak current Ip3 in the third pulse period T3 is preferably different from the second peak current Ip2 in the second pulse period T2, as disclosed in Japanese Patent Application Laid-Open No. 2009-233728. .

Another control method for shifting to the second pulse period T2 when the detachment detection signal is not detected within the third pulse period T3, which is the fixed waveform control period, will be described with reference to FIG. do. FIG. 8 is a graph for explaining a control method for the next second peak period Tp2 when the detachment detection signal is not detected even after performing fixed waveform control.

When the detachment detection signal is not detected within the third pulse period T3, the current value Ip2 in the second peak period Tp2 of the next period is set to the predetermined fixed value Ic1 with respect to the predetermined second peak current reference value Ip2_ref. It is preferable to control so that the subtracted value is applied. If the detachment detection signal is not detected within the third pulse period T3, a phenomenon may occur in which the arc length becomes excessive during the next pulse period, that is, within the second pulse period T2. It is possible to stabilize the transfer of droplets, and thus to suppress the disturbance of the regularity of the transfer of droplets.

Furthermore, when a short-circuit signal is detected during the first pulse period T1, a phenomenon in which the arc voltage drops may occur and the regularity of droplet transfer may be disturbed. A control method in this case will be described with reference to FIG. FIG. 9 is a graph showing an example of a control method when a short-circuit signal is detected during the first pulse period T1.

When a short-circuit signal is detected during the first pulse period T1, the current value Ip2 of the second peak period Tp2 of the next pulse period is set to a predetermined fixed value Ic2 with respect to a predetermined second peak current reference value Ip2_ref. should be controlled to apply an increased value. By this control, it is possible to more effectively suppress disturbance of the regularity of droplet transfer due to lengthening of the arc length.

Also, when arc instability is detected in the second pulse period T2, the regularity of droplet transfer in the next pulse period may be disturbed. A control method in this case will be described with reference to FIG. FIG. 9 is a graph showing an example of a control method when arc instability is detected during the second pulse period T2. As shown in FIG. 9, in order to eliminate the disturbance in the regularity of droplet transfer in the next pulse cycle, the current value Ip1 in the first peak period Tp1 of the next pulse cycle must be set to the predetermined first peak current Control may be performed so that a value obtained by increasing a predetermined fixed value Ic3 is applied to the reference value Ip1_ref. Note that the detection of arc instability means the detection of arc deflection in the present embodiment, and the arc deflection is detected when a steep voltage rise signal exceeding a predetermined threshold value is confirmed within the second pulse period T2. I judge.

Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment, and can be modified, improved, etc. as appropriate. For example, in the above embodiment, the output current control circuit 70 and the pulse waveform correction circuit 80 are configured independently, but they may be integrated into one circuit.

As described above, the following items are disclosed in this specification.

(1) A welding control method for controlling the waveform of a welding current in gas shielded arc welding, comprising:
The waveform of the welding current is a pulse waveform in which one cycle is a first pulse period for detaching a droplet and a second pulse period for forming a sufficiently large droplet at the tip of the welding wire. and
The first pulse period is composed of a predetermined first peak period having a first peak current value and a first base period after the first peak period,
The second pulse period is composed of a predetermined second peak period having a second peak current value lower than the first peak current value, and a second base period after the second peak period,
a voltage detection step of outputting a voltage detection signal Vo;
When the difference between the voltage detection signal Vo and the predetermined set voltage Vs is used as the difference signal, a voltage deviation average value Verrp2_ave in a predetermined section within the second pulse period is calculated based on the difference signal. a voltage deviation average calculation step;
and a controlled variable calculation step of calculating a controlled variable for at least one of the first peak current value and the second peak current value based on the voltage deviation average value Verrp2_ave.
According to this configuration, by controlling at least one of the first peak current value in the first pulse period and the second peak current value in the second pulse period, it is possible to suppress the regularity of droplet transfer from being disturbed. Spatter generation can be further reduced.

(2) The welding control method according to (1), wherein the voltage deviation average value Verrp2_ave is calculated based on the entire second pulse period.
According to this configuration, the accuracy of the voltage deviation average value Verrp2_ave is improved, and welding can be controlled with higher accuracy.

(3) In the controlled variable calculation step, when calculating the controlled variable of at least one of the first peak current value and the second peak current value, At least one control amount range is determined in advance,
base time and base current in the second base period when at least one of the calculated control amount of the first peak current value and the second peak current value is out of the predetermined control amount range; And the welding control method according to (1) or (2), wherein at least one of a base time and a base current value in the first base period is controlled.
According to this configuration, even when the control amount of the second peak current value is out of the control amount range, it is possible to suppress the regularity of droplet transfer from being disturbed.

(4) In the control amount calculation step,
multiplying the voltage deviation average value Verrp2_ave by at least a predetermined gain value P2_gain and a correction coefficient to calculate a current manipulated variable Di;
A peak current control amount Di_sum for increasing or decreasing at least one of the first peak current value and the second peak current value is calculated as an integrated value of the current manipulated variable Di from an arbitrary past cycle to the current cycle. , (1) to (3).
According to this configuration, the amount of welding wire 22 melted during the second pulse period T2 can be controlled more accurately.

(5) The correction coefficient is a current correction coefficient Ic_ave,
The welding control method according to (4), wherein the current correction coefficient Ic_ave includes at least a value obtained by adding a predetermined welding current setting signal Is and the peak current control amount Di_sum.
According to this configuration, the amount of welding wire 22 melted during the second pulse period T2 can be controlled more accurately.

(6) The welding control method according to (4) or (5), wherein the gain value P2_gain is set based on at least the feeding speed of the welding wire or the set welding current.
According to this configuration, an appropriate gain value can be set based on the welding wire feed speed or the set welding current.

(7) According to any one of (1) to (6), the rising portion and the falling portion in at least one of the first peak period and the second peak period have a slope of three steps or less. welding control method.
According to this configuration, it becomes easier to grasp the detachment detection signal, and it is possible to more effectively suppress the disturbance of the regularity of droplet transfer.

(8) The welding control method according to any one of (1) to (7), wherein the falling portion in the first peak period consists of a first slope section, a constant current section and a second slope section.
According to this configuration, it becomes easier to grasp the detachment detection signal, and it is possible to more effectively suppress the disturbance of the regularity of droplet transfer.

(9) when no detachment detection signal is detected in the trailing portion of the first peak period,
The welding control method according to (8), wherein a predetermined fixed waveform control is added during the first base period.
According to this configuration, the droplet transfer can be stabilized more effectively, and the disturbance of the regularity of the droplet transfer can be suppressed.

(10) When the departure detection signal is not detected during the fixed waveform control,
The welding control method according to (9), wherein a value obtained by subtracting a predetermined fixed value Ic1 from a predetermined second peak current reference value is applied as the second peak current value in the next pulse period.
According to this configuration, the droplet transfer can be stabilized more effectively, and the disturbance of the regularity of the droplet transfer can be suppressed.

(11) when a short-circuit signal is detected during the first pulse period,
Any one of (1) to (10), wherein a value obtained by adding a predetermined fixed value Ic2 to a predetermined second peak current reference value is applied as the second peak current value in the next pulse period. The welding control method described in 1.
According to this configuration, it is possible to more effectively suppress the disturbance of the regularity of droplet transfer due to the lengthening of the arc.

(12) When arc instability is detected during the second pulse period, a predetermined fixed value Ic3 with respect to a predetermined first peak current reference value is set as the first peak current value in the next pulse period. The welding control method according to any one of (1) to (11), wherein the added value is applied.
According to this configuration, it is possible to more effectively suppress the disturbance of the droplet transfer regularity in the next pulse cycle.

(13) A welding power source that performs waveform control of a welding current in gas shielded arc welding,
The waveform of the welding current is a pulse waveform in which one cycle is a first pulse period for detaching a droplet and a second pulse period for forming a sufficiently large droplet at the tip of the welding wire. and
The first pulse period is composed of a predetermined first peak period having a first peak current value and a first base period after the first peak period,
The second pulse period is composed of a predetermined second peak period having a second peak current value lower than the first peak current value, and a second base period after the second peak period,
voltage detection means for outputting a voltage detection signal Vo;
When the difference between the voltage detection signal Vo and the predetermined set voltage Vs is used as the difference signal, a voltage deviation average value Verrp2_ave in a predetermined section within the second pulse period is calculated based on the difference signal. voltage deviation average calculation means;
and control amount calculation means for calculating a control amount for at least one of the first peak current value and the second peak current value based on the voltage deviation average value Verrp2_ave.
According to this configuration, by controlling at least one of the first peak current value in the first pulse period and the second peak current value in the second pulse period, it is possible to suppress the regularity of droplet transfer from being disturbed. Spatter generation can be further reduced.

(14) A welding system comprising at least a welding robot, a feeding device, a welding power source, a shielding gas supply device, and a welding control device, and used for waveform control of welding current in gas-shielded arc welding,
The waveform of the welding current is a pulse waveform in which one cycle is a first pulse period for detaching a droplet and a second pulse period for forming a sufficiently large droplet at the tip of the welding wire. and
The first pulse period is composed of a predetermined first peak period having a first peak current value and a first base period after the first peak period,
The second pulse period is composed of a predetermined second peak period having a second peak current value lower than the first peak current value, and a second base period after the second peak period,
The welding power source is
voltage detection means for outputting a voltage detection signal Vo;
When the difference between the voltage detection signal Vo and the predetermined set voltage Vs is used as the difference signal, a voltage deviation average value Verrp2_ave in a predetermined section within the second pulse period is calculated based on the difference signal. voltage deviation average calculation means;
and control amount calculation means for calculating a control amount for at least one of the first peak current value and the second peak current value based on the voltage deviation average value Verrp2_ave.
According to this configuration, by controlling at least one of the first peak current value in the first pulse period and the second peak current value in the second pulse period, it is possible to suppress the regularity of droplet transfer from being disturbed. Spatter generation can be further reduced.

(15) A welding method for arc welding while controlling the waveform of the welding current in gas shielded arc welding,
At least one of carbon dioxide gas, nitrogen gas, hydrogen gas and oxygen gas is included as the shielding gas used for arc welding,
The waveform of the welding current is a pulse waveform in which one cycle is a first pulse period for detaching a droplet and a second pulse period for forming a sufficiently large droplet at the tip of the welding wire. and
The first pulse period is composed of a predetermined first peak period having a first peak current value and a first base period after the first peak period,
The second pulse period is composed of a predetermined second peak period having a second peak current value lower than the first peak current value, and a second base period after the second peak period,
As the waveform control method,
a voltage detection step of outputting a voltage detection signal Vo;
When the difference between the voltage detection signal Vo and the predetermined set voltage Vs is used as the difference signal, a voltage deviation average value Verrp2_ave in a predetermined section within the second pulse period is calculated based on the difference signal. a voltage deviation average calculation step;
and a controlled variable calculation step of calculating a controlled variable for at least one of the first peak current value and the second peak current value based on the voltage deviation average value Verrp2_ave.
According to this configuration, in gas-shielded arc welding, the shield gas contains a component with a high potential gradient such as carbon dioxide gas, nitrogen gas, hydrogen gas, and oxygen gas, so that the form of droplet transfer is changed to globular transfer. Even so, by controlling at least one of the first peak current value in the first pulse period and the second peak current value in the second pulse period, it is possible to suppress the disturbance of the regularity of droplet transfer, thereby reducing spattering. can be further reduced.

(16) A layered manufacturing method that performs layered manufacturing while controlling the waveform of a welding current in layered manufacturing that applies gas shielded arc welding,
At least one gas selected from carbon dioxide gas, nitrogen gas, hydrogen gas, and oxygen gas is included as the shielding gas used in the gas-shielded arc welding,
The waveform of the welding current is a pulse waveform in which one cycle is a first pulse period for detaching a droplet and a second pulse period for forming a sufficiently large droplet at the tip of the welding wire. and
The first pulse period is composed of a predetermined first peak period having a first peak current value and a first base period after the first peak period,
The second pulse period is composed of a predetermined second peak period having a second peak current value lower than the first peak current value, and a second base period after the second peak period,
As the waveform control method,
a voltage detection step of outputting a voltage detection signal Vo;
When the difference between the voltage detection signal Vo and the predetermined set voltage Vs is used as the difference signal, a voltage deviation average value Verrp2_ave in a predetermined section within the second pulse period is calculated based on the difference signal. a voltage deviation average calculation step;
and a controlled variable calculation step of calculating a controlled variable for at least one of the first peak current value and the second peak current value based on the voltage deviation average value Verrp2_ave.
According to this configuration, in additive manufacturing using gas-shielded arc welding, the inclusion of components with a high potential gradient such as carbon dioxide gas, nitrogen gas, hydrogen gas, and oxygen gas in the shielding gas prevents droplet transfer. Even if the form takes globular transfer, controlling at least one of the first peak current value in the first pulse period and the second peak current value in the second pulse period disturbs the regularity of droplet transfer. can be suppressed, and the occurrence of spatter can be further reduced.

Various embodiments have been described above with reference to the drawings, but it goes without saying that the present invention is not limited to such examples. It is obvious that a person skilled in the art can conceive of various modifications or modifications within the scope described in the claims, and these also belong to the technical scope of the present invention. Understood. Moreover, each component in the above embodiments may be combined arbitrarily without departing from the gist of the invention.

This application is based on a Japanese patent application (Japanese Patent Application No. 2021-061901) filed on March 31, 2021, the contents of which are incorporated herein by reference.

10 arc welding system 20 welding robot 22 welding wires 23 to 27 droplets 30 welding power source 40 control device (welding control device)
80 pulse waveform correction circuit 81 voltage deviation average calculation unit (voltage deviation average calculation means)
82 pulse waveform control amount calculation unit (control amount calculation means)
Di Manipulated current value Di_sum Manipulated peak current value Ib1 First base current value Ib1_ref First base current reference value Ib2 Second base current value Ib2_ref Second base current reference value Ic1, Ic2, Ic3 Predetermined fixed value Ic_ave Current correction coefficient Ip1 First peak current value Ip1_ref First peak current reference value Ip2 Second peak current value Ip2_ref Second peak current reference value P2_gain Gain value T1 First pulse period T2 Second pulse period T3 Third pulse period (fixed waveform control)
Tb1 First base period Tb2 Second base period Td Falling section Td1 First slope section Tdc Hold section (constant current section)
Td2 Second slope section Tp1 First peak period Tp2 Second peak period Tu Rise portion VD Voltage detection section (voltage detection means)
Verrp2 Second pulse difference signal Verrp2_ave Voltage deviation average value Verrp2_sum Voltage deviation integrated value Vo Voltage detection signal Vs Voltage setting signal (set voltage)

Claims (21)

1. A welding control method for controlling the waveform of a welding current in gas shielded arc welding,
   The waveform of the welding current is a pulse waveform in which one cycle is a first pulse period for detaching a droplet and a second pulse period for forming a sufficiently large droplet at the tip of the welding wire. and
   The first pulse period is composed of a predetermined first peak period having a first peak current value and a first base period after the first peak period,
   The second pulse period is composed of a predetermined second peak period having a second peak current value lower than the first peak current value, and a second base period after the second peak period,
   a voltage detection step of outputting a voltage detection signal Vo;
   When the difference between the voltage detection signal Vo and the predetermined set voltage Vs is used as the difference signal, a voltage deviation average value Verrp2_ave in a predetermined section within the second pulse period is calculated based on the difference signal. a voltage deviation average calculation step;
   and a controlled variable calculation step of calculating a controlled variable for at least one of the first peak current value and the second peak current value based on the voltage deviation average value Verrp2_ave.
2. The welding control method according to claim 1, wherein the voltage deviation average value Verrp2_ave is calculated from the entire second pulse period.
3. In the controlled variable calculation step, in calculating the controlled variable of at least one of the first peak current value and the second peak current value, at least one of the first peak current value and the second peak current value Predetermine the control amount range,
   base time and base current in the second base period when at least one of the calculated control amount of the first peak current value and the second peak current value is out of the predetermined control amount range; and at least one of a base time and a base current value in the first base period.
4. In the control amount calculation step,
   multiplying the voltage deviation average value Verrp2_ave by at least a predetermined gain value P2_gain and a correction coefficient to calculate a current manipulated variable Di;
   A peak current control amount Di_sum for increasing or decreasing at least one of the first peak current value and the second peak current value is calculated as an integrated value of the current manipulated variable Di from an arbitrary past cycle to the current cycle. The welding control method according to claim 1 or 2.
5. Let the correction coefficient be a current correction coefficient Ic_ave,
   The welding control method according to claim 4, wherein said current correction coefficient Ic_ave includes at least a value obtained by adding a predetermined welding current setting signal Is and said peak current control amount Di_sum.
6. In the control amount calculation step,
   multiplying the voltage deviation average value Verrp2_ave by at least a predetermined gain value P2_gain and a correction coefficient to calculate a current manipulated variable Di;
   A peak current control amount Di_sum for increasing or decreasing at least one of the first peak current value and the second peak current value is calculated as an integrated value of the current manipulated variable Di from an arbitrary past cycle to the current cycle. 4. The welding control method according to claim 3.
7. Let the correction coefficient be a current correction coefficient Ic_ave,
   The welding control method according to claim 6, wherein said current correction coefficient Ic_ave includes at least a value obtained by adding a predetermined welding current setting signal Is and said peak current control amount Di_sum.
8. The welding control method according to claim 4, wherein the gain value P2_gain is set based on at least the feeding speed of the welding wire or a set welding current.
9. The welding control method according to claim 5, wherein the gain value P2_gain is set based on at least the feeding speed of the welding wire or a set welding current.
10. The welding control method according to claim 6, wherein the gain value P2_gain is set based on at least the feeding speed of the welding wire or a set welding current.
11. The welding control method according to claim 7, wherein the gain value P2_gain is set based on at least the feeding speed of the welding wire or a set welding current.
12. The welding control method according to claim 1 or 2, wherein the rising portion and the falling portion in at least one of the first peak period and the second peak period have an inclination of three steps or less.
13. The welding control method according to claim 1 or 2, wherein the falling portion in the first peak period consists of a first slope section, a constant current section and a second slope section.
14. when no detachment detection signal is detected in the falling portion of the first peak period,
    14. The method of controlling welding according to claim 13, further comprising adding a predetermined fixed waveform control during said first base period.
15. When the detachment detection signal is not detected during the fixed waveform control,
    15. The welding control method according to claim 14, wherein a value obtained by subtracting a predetermined fixed value Ic1 from a predetermined second peak current reference value is applied as the second peak current value in the next pulse period.
16. when a short-circuit signal is detected during the first pulse period,
    The welding control method according to claim 1 or 2, wherein a value obtained by adding a predetermined fixed value Ic2 to a predetermined second peak current reference value is applied as the second peak current value in the next pulse period. .
17. A value obtained by adding a predetermined fixed value Ic3 to a predetermined first peak current reference value as the first peak current value in the next pulse period when arc instability is detected during the second pulse period. The welding control method according to claim 1 or 2, applying
18. A welding power source that performs waveform control of welding current in gas shielded arc welding,
    The waveform of the welding current is a pulse waveform in which one cycle is a first pulse period for detaching a droplet and a second pulse period for forming a sufficiently large droplet at the tip of the welding wire. and
    The first pulse period is composed of a predetermined first peak period having a first peak current value and a first base period after the first peak period,
    The second pulse period is composed of a predetermined second peak period having a second peak current value lower than the first peak current value, and a second base period after the second peak period,
    voltage detection means for outputting a voltage detection signal Vo;
    When the difference between the voltage detection signal Vo and the predetermined set voltage Vs is used as the difference signal, a voltage deviation average value Verrp2_ave in a predetermined section within the second pulse period is calculated based on the difference signal. voltage deviation average calculation means;
    and control amount calculation means for calculating a control amount for at least one of the first peak current value and the second peak current value based on the voltage deviation average value Verrp2_ave.
19. A welding system comprising at least a welding robot, a feeding device, a welding power source, a shielding gas supply device, and a welding control device, and used for waveform control of a welding current in gas-shielded arc welding,
    The waveform of the welding current is a pulse waveform in which one cycle is a first pulse period for detaching a droplet and a second pulse period for forming a sufficiently large droplet at the tip of the welding wire. and
    The first pulse period is composed of a predetermined first peak period having a first peak current value and a first base period after the first peak period,
    The second pulse period is composed of a predetermined second peak period having a second peak current value lower than the first peak current value, and a second base period after the second peak period,
    The welding power source is
    voltage detection means for outputting a voltage detection signal Vo;
    When the difference between the voltage detection signal Vo and the predetermined set voltage Vs is used as the difference signal, a voltage deviation average value Verrp2_ave in a predetermined section within the second pulse period is calculated based on the difference signal. voltage deviation average calculation means;
    and control amount calculation means for calculating a control amount for at least one of the first peak current value and the second peak current value based on the voltage deviation average value Verrp2_ave.
20. A welding method for arc welding while controlling the waveform of the welding current in gas shielded arc welding,
    At least one of carbon dioxide gas, nitrogen gas, hydrogen gas and oxygen gas is included as the shielding gas used for arc welding,
    The waveform of the welding current is a pulse waveform in which one cycle is a first pulse period for detaching a droplet and a second pulse period for forming a sufficiently large droplet at the tip of the welding wire. and
    The first pulse period is composed of a predetermined first peak period having a first peak current value and a first base period after the first peak period,
    The second pulse period is composed of a predetermined second peak period having a second peak current value lower than the first peak current value, and a second base period after the second peak period,
    As the waveform control method,
    a voltage detection step of outputting a voltage detection signal Vo;
    When the difference between the voltage detection signal Vo and the predetermined set voltage Vs is used as the difference signal, a voltage deviation average value Verrp2_ave in a predetermined section within the second pulse period is calculated based on the difference signal. a voltage deviation average calculation step;
    and a controlled variable calculation step of calculating a controlled variable for at least one of the first peak current value and the second peak current value based on the voltage deviation average value Verrp2_ave.
21. A layered manufacturing method for performing layered manufacturing while controlling the waveform of a welding current in layered manufacturing applying gas shielded arc welding,
    At least one gas selected from carbon dioxide gas, nitrogen gas, hydrogen gas, and oxygen gas is included as the shielding gas used in the gas-shielded arc welding,
    The waveform of the welding current is a pulse waveform in which one cycle is a first pulse period for detaching a droplet and a second pulse period for forming a sufficiently large droplet at the tip of the welding wire. and
    The first pulse period is composed of a predetermined first peak period having a first peak current value and a first base period after the first peak period,
    The second pulse period is composed of a predetermined second peak period having a second peak current value lower than the first peak current value, and a second base period after the second peak period,
    As the waveform control method,
    a voltage detection step of outputting a voltage detection signal Vo;
    When the difference between the voltage detection signal Vo and the predetermined set voltage Vs is used as the difference signal, a voltage deviation average value Verrp2_ave in a predetermined section within the second pulse period is calculated based on the difference signal. a voltage deviation average calculation step;
    and a controlled variable calculation step of calculating a controlled variable for at least one of the first peak current value and the second peak current value based on the voltage deviation average value Verrp2_ave.

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