JP2024027931A - Feed control method for pulsed arc welding - Google Patents

Abstract

An object of the present invention is to reliably realize one droplet transfer state for one pulse period in consumable electrode type pulsed arc welding in response to various welding conditions. A feed control method for pulsed arc welding in which a welding wire is fed and welding is performed by repeating energization of a peak current Ip during a peak period Tp and a base current Ib during a base period Tb as one pulse period. During the period t2 to t21 of the period Tb, the welding wire is fed at a forward and reverse feeding speed Fw. The feeding speed Fw is controlled so that the average value of the forward and reverse feeding and the normal feeding during the peak period Tp are the same value. [Selection diagram] Figure 2

Description

The present invention relates to a feed control method for consumable electrode pulse arc welding.

In consumable electrode pulse arc welding, a welding wire is fed at a constant speed, and welding is performed by repeating a peak period in which a peak current and peak voltage are output and a base period in which a base current and voltage are output as one pulse period. be exposed. The peak current is set to a large current value of about 500 A, which is higher than the critical current value, and the welding wire is melted to form and transfer droplets. The base current is set to about 50 A, which is less than the critical current value, and the welding wire hardly melts. When the welding current value exceeds the critical current value, the droplet transfer cell enters the spray transfer state. In pulsed arc welding, it is important to maintain a state of one droplet transfer per pulse cycle, in which one droplet is transferred by applying a single peak current, in order to obtain a high-quality weld bead with less spatter. It is.

In order to achieve the above-mentioned one pulse period one droplet transfer state, the peak current value, peak period, etc. must be adjusted under various welding conditions such as the diameter of the welding wire, the material of the base metal, the type of shielding gas, the average welding current value, etc. It is necessary to set the pulse waveform parameters to appropriate values. In the invention of Patent Document 1, pulse waveform parameters are automatically set so that a short circuit between the welding wire and the base metal occurs at a desired timing. A state in which a short circuit occurs at a desired timing indicates that the droplet is moving due to the short circuit, and is in a state where one droplet moves in one pulse period.

Japanese Patent Application Publication No. 2014-226677

Even if the pulse waveform parameters are optimized using conventional techniques, there are certain variations in the droplet formation, so that a situation occurs where the droplet does not migrate during the pulse period. In particular, when the material of the welding wire is aluminum, the droplets become elongated, and a situation where the droplets do not migrate during the pulse period is likely to occur.

Therefore, it is an object of the present invention to provide a feed control method for pulsed arc welding that can reliably achieve one droplet transfer state in one pulse cycle under various welding conditions, and that enables high-quality welding. purpose.

In order to solve the above-mentioned problem, the invention of claim 1:
In a feeding control method for pulsed arc welding in which welding is performed by feeding a welding wire and repeating energization of a peak current during a peak period and a base current during a base period as one pulse period,
feeding the welding wire forward and backward during part or all of the base period;
This is a feed control method for pulsed arc welding characterized by the following.

The invention of claim 2 is:
The amplitude of the forward and reverse feeds of the forward and reverse feeds is greater than the value of the forward feed during the peak period.
2. A feed control method for pulsed arc welding according to claim 1.

The invention of claim 3 is:
The forward and reverse feeding starts from reverse feeding,
3. A feed control method for pulsed arc welding according to claim 1 or 2, characterized in that:

The invention of claim 4 is:
setting the average value of the forward and reverse feeding to the same value as the value of the forward feeding during the peak period;
3. A feed control method for pulsed arc welding according to claim 1 or 2, characterized in that:

According to the present invention, under various welding conditions, it is possible to reliably realize one droplet transfer state in one pulse period, and high-quality welding is possible.

1 is a block diagram of a welding power source for carrying out a pulsed arc welding feed control method according to an embodiment of the present invention. 2 is a timing chart of each signal in the welding power source of FIG. 1 illustrating a feed control method for pulsed arc welding according to an embodiment of the present invention.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a welding power source for carrying out a pulsed arc welding feed control method according to an embodiment of the present invention. Each block will be explained below with reference to the same figure.

The main power supply circuit MC receives a commercial power supply (not shown) such as a three-phase 200V power supply, performs output control such as inverter control according to a current error amplification signal Ei to be described later, and outputs an output voltage suitable for welding.

Reactor WL smoothes the output of power supply main circuit MC.

The feed motor WM receives a feed control signal Fc, which will be described later, as an input and feeds the welding wire 1 at a feed speed Fw. The welding wire 1 is fed forward and backward during part or all of the base period, and is fed forward during the other periods. A motor with good transient characteristics is used as the feed motor WM. In order to speed up the rate of change in the feed speed Fw of the welding wire 1 and the reversal of the feed direction, the feed motor WM may be installed near the tip of the welding torch 4. Further, two feeding motors WM may be used to form a push-pull feeding system.

The welding wire 1 is fed through the welding torch 4 by rotation of the feed roll 5 coupled to the wire feed motor WM, and an arc 3 is generated between the welding wire 1 and the base metal 2. A welding voltage Vw is applied between a power supply tip (not shown) in the welding torch 4 and the base metal 2, and a welding current Iw is applied. Shielding gas (not shown) is ejected from the tip of the welding torch 4 to shield the arc 3 from the atmosphere. The material of the base material 2 is steel, aluminum, etc. The shielding gas is a mixed gas of carbon dioxide gas and argon gas, argon gas, or the like.

Voltage detection circuit VD detects the above-mentioned welding voltage Vw and outputs voltage detection signal Vd. The voltage averaging circuit VAV averages the voltage detection signal Vd described above and outputs a voltage average signal Vav. The voltage setting circuit VR outputs a predetermined voltage setting signal Vr.

The voltage error amplification circuit EV amplifies the error between the voltage setting signal Vr and the voltage average signal Vav, and outputs a voltage error amplification signal Ev.

The V/F converter VF outputs a pulse periodic signal Tf that is at a high level for a short time every period corresponding to the voltage error amplification signal Ev. This pulse period signal Tf is a signal that determines a period in which the peak period and the base period are one period.

The base current setting circuit IBR outputs a predetermined base current setting signal Ibr.

The peak current setting circuit IPR outputs a predetermined peak current setting signal Ipr. The peak current setting signal Ipr is set to about 400 to 600 A depending on the diameter, material, feeding speed, etc. of the welding wire. The peak period setting circuit TPR outputs a predetermined peak period setting signal Tpr. The peak current setting signal Ipr and the peak period setting signal Tpr are set in accordance with the welding conditions so that one pulse period causes one droplet transfer state.

The peak period timer circuit TTP receives the above-mentioned pulse period signal Tf and the above-mentioned peak period setting signal Tpr as input, and operates during the peak period Tp determined by the peak period setting signal Tpr every time the pulse period signal Tf becomes High level for a short time. It outputs a peak period signal Ttp which becomes High level and then becomes Low level. Therefore, this peak period signal Ttp is a signal that is at a high level during the peak period Tp and is at a low level during the base period Tb.

The current setting circuit IR inputs the base current setting signal Ibr, the peak current setting signal Ipr, and the peak period signal Ttp, and sets the peak current setting signal Ipr as the current when the peak period signal Ttp is at a high level. When the peak period signal Ttp is at a low level, the base current setting signal Ibr is output as the current setting signal Ir.

The current detection circuit ID detects the above-mentioned welding current Iw and outputs a current detection signal Id. The current error amplification circuit EI amplifies the error between the current setting signal Ir and the current detection signal Id, and outputs a current error amplification signal Ei.

The feed rate setting circuit FR outputs a predetermined feed rate setting signal fr for setting the feed rate for forward feeding other than the forward and reverse feeding periods.

The amplitude setting circuit AR outputs a predetermined amplitude setting signal Ar. The period setting circuit SR outputs a predetermined period setting signal Sr.

The forward/reverse feeding period timer circuit TFR receives the above-mentioned peak period signal Ttp as an input, and maintains a positive level that is at a high level for a predetermined period from the time when the peak period signal Ttp changes to a low level or during the entire period of the low level. A reverse feed period signal Tfr is output. Therefore, the forward/reverse feed period signal Tfr is a signal that remains at High level for a predetermined period from the start of the base period or for the entire period of the base period.

The feed speed control setting circuit FCR receives the above forward/reverse feed period signal Tfr, the above feed speed setting signal Fr, the above amplitude setting signal Ar, and the above period setting signal Sr, and performs the following processing. , outputs a feed rate control setting signal Fcr.
1) When the forward/reverse feed period signal Tfr is at a low level, the feed rate setting signal Fr is output as the feed rate control setting signal Fcr. As a result, forward feeding is performed during periods other than the forward and reverse feeding periods.
2) When the forward and reverse feeding period signal Tfr is at High level, the waveform that oscillates in positive and negative directions around 0 with the amplitude of the amplitude setting signal Ar and the period of the period setting signal Sr is changed by the value of the feeding speed setting signal Fr. The vibration waveform shifted to the positive side is output as the feed speed control setting signal Fcr. The vibration waveform may be a sine wave, a triangular wave, a trapezoidal wave, a rectangular wave, or the like. Thereby, the welding wire 1 is fed forward and backward during the forward and reverse feeding period.

The feed control circuit FC inputs the above feed speed control setting signal Fcr and sends a feed control signal Fc to the above feed motor for feeding the welding wire 1 at a feed speed Fw corresponding to this value. Output to WM.

FIG. 2 is a timing chart of each signal in the welding power source of FIG. 1, showing a feed control method for pulsed arc welding according to an embodiment of the present invention. The same figure (A) shows the time change of the welding current Iw, the same figure (B) shows the time change of the welding voltage Vw, the same figure (C) shows the time change of the forward and reverse feeding period signal Tfr, and the same figure (C) shows the time change of the forward and reverse feeding period signal Tfr. Figure (D) shows the change in feeding speed Fw over time. The operation of each signal will be explained below with reference to the same figure.

In the figure, the period from time t1 to t3 represents one pulse period. The period from time t1 to t2 is the peak period Tp, and the period from time t2 to t3 is the base period Tb.

During a predetermined peak period Tp from time t1 to t2, a predetermined peak current Ip is applied as shown in the figure (A), and as shown in the figure (B), the peak current Ip is proportional to the arc length. Voltage is applied. The peak current Ip is set by the peak current setting signal Ipr shown in FIG. During the peak period Tp, the tip of the welding wire is melted and a droplet is formed, and during the base period Tb after the end of the peak period Tp, the droplet transfers to a molten pool (one pulse period, one droplet transfer). situation). The peak period Tp and the peak current Ip are set so that one droplet transfer state occurs in one pulse period. A predetermined rise period and fall period may be provided for the peak current Ip. For example, the peak current Ip is set to about 500 A, and the peak period Tp is set to about 1.7 ms. As shown in FIG. 3C, the forward/reverse feeding period signal Tfr remains at the Low level. As shown in FIG. 1D, the feeding speed Fw becomes the value of the feeding speed setting signal Fr in FIG. 1, and the welding wire is fed forward at a constant speed.

The period from time t2 to t3 is the base period Tb. Time t1 to t3 constitutes one pulse period. The pulse period (pulse frequency) is feedback-controlled (frequency modulation control) so that the average value of the welding voltage Vw becomes equal to the value of the voltage setting signal Vr in FIG. 1. Thereby, the average value of the arc length is maintained at an appropriate value.

During the base period Tb, as shown in the figure (A), a predetermined base current Ib is applied, and as shown in the figure (B), a base voltage proportional to the arc length is applied. Base current Ib is set by base current setting signal Ibr shown in FIG. The base current Ib is set to a small current value that hardly melts the welding wire. For example, the base current Ib is set to about 50A.

During the period from time t2 to time t21 from the start of the base period Tb until the elapse of a predetermined period, the forward/reverse feed period signal Tfr becomes High level, as shown in FIG. period. In response to this, as shown in FIG. 1D, the feed rate Fw oscillates around 0 with the amplitude of the amplitude setting signal Ar in FIG. 1 and the period of the period setting signal Sr in FIG. The vibration waveform is obtained by shifting the waveform to the positive side by the value of the feed rate setting signal Fr shown in FIG. Therefore, the average value of the feed rate Fw during the forward and reverse feed period becomes the value of the feed rate setting signal Fr in FIG. 1, which is the same value as the peak period Tp. Therefore, the average value of the feed rate Fw remains constant during the entire welding period. Here, by changing the positive shift amount described above, the average value of the feeding speed Fw can be set to a value different from the peak period Tp. In order to vibrate the tip of the welding wire, the amplitudes of the forward feed and reverse feed are larger than the value of the feed speed setting signal Fr. Further, the forward and reverse feeding period starts from the reverse feeding. The value of the feed speed setting signal Fr is set to about 3 to 10 m/min. The value of the amplitude setting signal Ar, which is the sum of the amplitudes of normal feeding and reverse feeding, is set to about 60 to 120 m/min. The value of the period setting signal Sr is set to about 1 to 4 ms. Although the vibration waveform is shown as a trapezoidal wave in the figure, it may be a sine wave, a triangular wave, a rectangular wave, or the like. The above forward and reverse feeding period may be the entire period of the base period Tb from time t2 to t3.

During the period from time t21 to time t3, the forward/reverse feeding period signal Tfr is at a low level, as shown in FIG. In response to this, as shown in the figure (D), the feeding speed Fw becomes the value of the feeding speed setting signal Fr shown in FIG. 1 again, and the welding wire is fed forward at a constant speed.

The effects of this embodiment will be explained below.
According to this embodiment, the welding wire is fed forward and backward during part or all of the base period. If the welding wire is fed forward and backward during the base period, the droplet formed at the tip of the welding wire will vibrate in the vertical direction. For this reason, the droplets can be separated by vibration and reliably transferred to the molten pool. Furthermore, since the droplets can be transferred without shorting between the welding wire and the base metal, it is possible to reduce the occurrence of spatter. As a result, in the present embodiment, under various welding conditions, it is possible to reliably achieve one droplet transfer state for one pulse period, and high-quality welding is possible.

More preferably, according to this embodiment, the amplitudes of the forward and reverse feeds are larger than the value of the forward feed during the peak period. In this way, the vibration amplitude of the droplet can be increased, so that the droplet can be separated more reliably.

More preferably, according to the present embodiment, forward and reverse feeding starts from reverse feeding. In this case, since the droplets start vibrating upward, short circuits between the welding wire and the base metal can be more reliably suppressed, and spatter generation can be further reduced.

More preferably, according to this embodiment, the average value of the forward and reverse feeds is set to the same value as the value of the forward feeds during the peak period. In this way, the average value of the feed rate remains constant during the entire welding period, resulting in a uniform bead appearance and improved welding quality.

1 Welding wire 2 Base metal 3 Arc 4 Welding torch 5 Feed roll AR Amplitude setting circuit Ar Amplitude setting signal EI Current error amplification circuit Ei Current error amplification signal EV Voltage error amplification circuit Ev Voltage error amplification signal FC Feed control circuit Fc Feed Feeding control signal FCR Feeding speed control setting circuit Fcr Feeding speed control setting signal FR Feeding speed setting circuit Fr Feeding speed setting signal Ib Base current IBR Base current setting circuit Ibr Base current setting signal ID Current detection circuit Id Current detection signal Ip Peak current IPR Peak current setting circuit Ipr Peak current setting signal IR Current setting circuit Ir Current setting signal Iw Welding current MC Power supply main circuit SR Period setting circuit Sr Period setting signal Tb Base period Tf Pulse period signal TFR Forward and reverse feeding period timer Circuit Tfr Forward/reverse feed period signal Tp Peak period TPR Peak period setting circuit Tpr Peak period setting signal TTP Peak period timer circuit Ttp Peak period signal VAV Voltage averaging circuit Vav Voltage averaging signal Vb Base voltage VD Voltage detection circuit Vd Voltage detection signal VF V/F converter VR Voltage setting circuit Vr Voltage setting signal Vw Welding voltage WL Reactor WM Feed motor

Claims (4)

In a feeding control method for pulsed arc welding in which welding is performed by feeding a welding wire and repeating energization of a peak current during a peak period and a base current during a base period as one pulse period,
feeding the welding wire forward and backward during part or all of the base period;
A feed control method for pulsed arc welding, characterized in that: The amplitude of the forward and reverse feeds of the forward and reverse feeds is greater than the value of the forward feed during the peak period.
The feed control method for pulsed arc welding according to claim 1, characterized in that: The forward and reverse feeding starts from reverse feeding,
The feed control method for pulsed arc welding according to claim 1 or 2, characterized in that: setting the average value of the forward and reverse feeding to the same value as the value of the forward feeding during the peak period;
The feed control method for pulsed arc welding according to claim 1 or 2, characterized in that:

Images