JP2022064569A - Gas shield arc welding method and gas shield arc welding apparatus - Google Patents

Abstract

To provide a gas shield arc welding method which suppresses generation of a slag of a silicon oxide and supplies a predetermined waveform of a pulse current, and thereby achieves regular droplet transfer and can stabilize welding, in pulse arc welding.SOLUTION: There is provided a gas shield arc welding method for supplying a pulse current to a welding wire, in which the welding wire contains less than 0.2 mass% of silicon, the pulse current is a multi-stage pulse including a first peak, a second peak and a transition part from the first peak to the second peak, a current value of the first peak is 530 A or more and 700 A or less, time of the first peak is 1.2 ms or less, and a current value of the second peak is smaller than the current value of the first peak.SELECTED DRAWING: Figure 2

Description

The present invention relates to a gas shielded arc welding method and a gas shielded arc welding apparatus.

A gas shielded arc welding method using a consumable electrode is widely used for welding a steel plate in a manufacturing process of an automobile or the like (for example, Patent Document 1). The welding wire as a consumable electrode generally contains 0.2 to 0.45% by mass of silicon Si, manganese Mn, carbon C, phosphorus P, sulfur S and the like.

Slag is generated in gas shielded arc welding. Slag is an oxide containing silicon Si or manganese Mn as a main component, and is separated and aggregated from the molten metal during welding and is formed on the bead. The portion where the oxide slag adheres to the surface of the welded steel sheet becomes defective in electrodeposition coating after welding, and the corrosion resistance is lowered. Among slags, silicon oxide has a low conductivity, which is a problem in electrodeposition coating.

Japanese Unexamined Patent Publication No. 2013-184216

As a method of suppressing defects in electrodeposition coating after welding, it is conceivable to reduce the content of silicon Si, which is the main component of slag, to less than 0.2% by mass.

However, reducing the silicon Si content of the weld wire reduces the viscosity of the molten metal formed at the tip of the weld wire during welding. When the viscosity of the molten metal decreases, the shape of the molten metal at the tip of the wire is not stable, and problems such as spattering occur. Even if pulse welding that realizes regular droplet transfer is used, it does not become 1 pulse 1 drop under general welding conditions, and the molten metal drips slowly from the tip of the welding wire, resulting in a short circuit. As a result, spatter is likely to occur.

An object of the present disclosure is to realize regular droplet migration and stabilize welding by suppressing the formation of silicon oxide slag and supplying a pulse current having a predetermined waveform in pulse arc welding. It is an object of the present invention to provide a gas shielded arc welding method and a gas shielded arc welding apparatus capable of performing.

The gas shielded arc welding method according to this embodiment is a gas shielded arc welding method in which a pulse current is supplied to a welding wire, and the welding wire contains less than 0.2% by mass of silicon, and the pulse current is the pulse current. It is a multi-stage pulse including the first peak, the second peak, and the transition part from the first peak to the second peak. The current value of the first peak is 530 A or more and 700 A or less, and the time of the first peak is 1.2 m. It is less than a second, and the current value of the second peak is smaller than the current value of the first peak.

The gas shielded arc welding apparatus according to this embodiment is a gas shielded arc welding apparatus that supplies a pulse current to a welding wire containing less than 0.2% by mass of silicon, and includes a power supply circuit that outputs the pulsed current. The first peak, the second peak, and the transition part from the first peak to the second peak are included, the current value of the first peak is 530 A or more and 700 A or less, and the time of the first peak is 1.2 ms or less. A control circuit for controlling the output of the power supply circuit is provided so that the pulse current whose current value of the second peak is smaller than the current value of the first peak is output.

According to the above, in pulse arc welding, by suppressing the formation of silicon oxide slag and supplying a pulse current having a predetermined waveform, regular droplet migration can be realized and welding can be stabilized. ..

It is a block diagram explaining the structural example of the gas shield arc welding apparatus which concerns on embodiment. It is explanatory drawing which shows the pulse current waveform which concerns on embodiment. It is a composition table of a welding wire. It is a graph of the experimental result which shows the pulse waveform setting value which realizes the regular droplet transition. It is a graph of the experimental result which shows the pulse waveform setting value which realizes the regular droplet transition. It is a graph of the experimental result showing the pulse waveform setting value which realizes a regular droplet transition. It is a graph of the experimental result which shows the pulse waveform setting value which realizes the regular droplet transition.

Specific examples of the arc welding method and the gas shielded arc welding apparatus according to the embodiment of the present invention will be described below with reference to the drawings. It should be noted that the present invention is not limited to these examples, and is indicated by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

Hereinafter, the present invention will be specifically described with reference to the drawings showing the embodiments thereof.
FIG. 1 is a block diagram illustrating a configuration example of a gas shielded arc welding device. The gas shielded arc welding device is a device for carrying out the gas shielded arc welding method according to the present embodiment, and includes a welding power supply 1, a torch 2, and a wire feeding unit 3.

The torch 2 is made of a conductive material such as a copper alloy, and has a cylindrical contact tip that guides the welding wire 5 to the welded portion of the base metal 4 and supplies the welding current Iw required for generating an arc. The contact tip comes into contact with the welding wire 5 penetrating the inside thereof, and supplies the welding current Iw to the welding wire 5. Further, the torch 2 has a hollow cylindrical shape surrounding the contact tip, and has a nozzle for injecting a shield gas to the welded portion.

The shield gas is a mixed gas of argon or ancestral argon and carbon dioxide gas. The mixed gas contains, for example, carbon dioxide gas of 10% or more and 30% or less, and argon or ancestral argon as a remaining component. The ancestral argon contains, for example, about 2-5% oxygen O2 in addition to argon.

The welding wire 5 is, for example, a solid wire. Its diameter is 0.6 mm or more and 1.6 mm or less, and it functions as a consumable electrode. The welding wire 5 is, for example, a pack wire housed in a pail pack in a spirally wound state, or a reel wire wound around a wire reel.

The welding wire 5 according to the present embodiment contains less than 0.2% by mass of silicon Si, manganese Mn, carbon C, phosphorus P, sulfur S and the like.

The weld wire 5 has a configuration in which silicon Si is less than 0.2% by mass, and the sum of the mass% of silicon Si and the mass% of manganese Mn is 1.5% by mass or more and 2.0% by mass or less. preferable. By adjusting the total amount of silicon Si and manganese Mn that function as deoxidizers to 1.5 to 2.0% while suppressing the content of silicon Si, the generation of blow holes and pits can be suppressed. When manganese Mn is contained in the welding wire 5, an oxide of manganese Mn is generated as slag during welding, but since the conductivity is higher than that of the oxide of silicon Si, electrodeposition coating failure after welding is defective. The problem can be suppressed to some extent.

More preferably, the silicon Si is less than 0.2% by mass, and the weld wire 5 contains manganese Mn of 1.5% by mass or more and 2.0% by mass or less and 0.05% by mass or more and 0.2% by mass. A configuration containing% or less of titanium Ti is preferable. Titanium Ti has a function of scattering manganese oxide generated during welding in the molten metal, and can suppress the formation of manganese oxide as slag on the surface of the base metal 4. Therefore, even when the welding wire 5 contains manganese Mn of nearly 2.0% by mass, the problem of electrodeposition coating failure after welding can be effectively suppressed.

The wire feeding unit 3 has a feeding roller that feeds the welded wire 5 to the torch 2, and a wire feeding motor WM that rotates the feeding roller. The wire feeding unit 3 pulls out the welding wire 5 from the pail pack or the wire reel by rotating the feeding roller, and supplies the drawn welding wire 5 to the torch 2 at a predetermined speed. The details of the feeding speed will be described later.

The welding power supply 1 includes a power supply circuit 11, a voltage detection circuit VD, a current detection circuit ID, and a control circuit 12.

The power supply circuit 11 is a circuit that is connected to the contact tip of the torch 2 and the base metal 4 via a power supply cable and outputs the welding current Iw and the welding voltage Vw, which are pulse currents. The power supply circuit 11 receives a commercial power supply such as 3-phase 200V (not shown) as an input, performs output control according to the output current difference setting signal Ei described later, and outputs a welding current Iw and a welding voltage Vw suitable for arc welding. .. The power supply circuit 11 includes a primary rectifier that rectifies a commercial power supply, a capacitor that smoothes the rectified DC, an inverter circuit that converts the smoothed DC into high-frequency AC, and a high-frequency step that steps down the high-frequency AC to a voltage value suitable for arc welding. A transformer, a secondary rectifier that rectifies stepped-down high-frequency AC, a reactor that smoothes rectified DC, and PWM modulation control based on the output current difference setting signal Ei described later to drive the transistors that make up the above inverter circuit. It is equipped with a drive circuit.

The voltage detection circuit VD detects the welding voltage Vw between the welding wire 5 and the base metal 4, and outputs a voltage detection signal Vd indicating the detected voltage value to the integration circuit SAV of the control circuit 12.

The current detection circuit ID is supplied from the welding power supply 1 to the welding wire 5 via the torch 2, detects the welding current Iw flowing through the arc, and outputs the current detection signal Id indicating the detected current value to the integration circuit SAV of the control circuit 12. Output to.

The control circuit 12 is a circuit that controls the output of the welding current Iw and the welding voltage Vw and the feeding speed of the welding wire 5, and is an integrator circuit SAV, a current setting circuit IS, a voltage setting circuit VS, an external characteristic setting circuit KS, and a waveform. It has a setting circuit WS, a waveform generation circuit FJ, an output current difference setting circuit EI, a feed rate setting circuit FC, and a feed control circuit FR. Each circuit constituting the control circuit 12 may be partially or wholly configured as hardware or may be configured as software.

The current setting circuit IS outputs the current setting signal Is to the integrating circuit SAV. The current setting signal Is is information indicating the set current Iset input to the welding power source 1 by the welding operator.

The voltage setting circuit VS outputs the voltage setting signal Vs to the integrating circuit SAV. The voltage setting signal Vs is information indicating the set voltage Vset input to the welding power supply 1 by the welding operator or the set voltage Vset as a standard value automatically determined based on the set current Iset.

The external characteristic setting circuit KS outputs an external characteristic setting signal Kss indicating the external characteristic Ks to the integrating circuit SAV. The external characteristic Ks may be a predetermined value or may be determined by the set current Iset and the set voltage Vset. The external characteristic is information indicating the ratio of the amount of decrease in the welding voltage Vw to the amount of increase in the welding current Iw output from the welding power source 1.

The integrator circuit SAV receives the voltage detection signal Vd, the current detection signal Id, the current setting signal Is, the voltage setting signal Vs, and the external characteristic setting signal Kss as inputs, and is at the start time of each pulse period Tp related to the pulse current. Is the starting point, and the voltage error integrated value Sva is calculated from each input signal. The voltage error integral value Sva is expressed by the following equation.
Sva = ∫ (Ks ・ Iw-Ks ・ Iset + Vset-Vw) ・ dt

The above equation is based on the external characteristic Ks, and when the operating point satisfies the external characteristic Ks, the value of the voltage error integral value Sva becomes 0 at the end point of any nth pulse period Tp. The integration circuit SAV outputs the low-level waveform end flag It to the waveform generation circuit FJ when the voltage error integration value Sva is not 0, and the high-level waveform end flag It when the voltage error integration value Sva becomes 0. Is output to the waveform generation circuit FJ. The high-level waveform end flag It indicates that the pulse period Tp of the welding current Iw, which is the pulse current, has ended.

The waveform setting circuit WS outputs a predetermined waveform setting signal Ws. The waveform setting signal Ws includes various pulse waveform setting values for determining the pulse waveform of the welding current Iw.

FIG. 2 is an explanatory diagram showing a pulse current waveform according to the embodiment. The horizontal axis is time, and the vertical axis is the welding current Iw, which indicates the time change of the pulse current. The welding current Iw according to the present embodiment is a pulse current, which is a multi-stage pulse current in which energization in the first peak period, energization in the second peak period, and energization in the base period are repeated as one pulse cycle Tp. Specifically, as shown in FIG. 2, the pulse current repeats a pulse period and a base period with a predetermined pulse period Tp, and the pulse period includes a peak rising period and a first peak period (first peak). ), Switching period (transition part), second peak period (second peak), and peak falling period.
The first peak current energized during the first peak period and the second peak current energized during the second peak period are larger than the set current Issue. The bale current energized during the base period is smaller than the set current Issue. The details of the pulse waveform set values such as the time of the first peak period and the first peak current, the time of the second peak period and the second peak current, the time of the switching period, and the repetition frequency fp of the pulse current will be described later.

The waveform generation circuit FJ receives the waveform setting signal Ws and the waveform end flag It as inputs, and outputs the current command signal Ir to the output current difference setting circuit EI. The current command signal Ir commands the absolute value of the welding current Iw.

The output current difference setting circuit EI receives the current detection signal Id and the current command signal Ir as inputs, and outputs the output current difference setting signal Ei. The output current difference setting signal Ei is a signal indicating the difference value between the current command signal Ir (+) and the current detection signal Id (−).

FIG. 3 is a composition table of the welding wire 5, and FIGS. 4 to 7 are graphs of experimental results showing pulse waveform set values that realize regular droplet transition. The components of the welding wire 5 used in the experiment are as shown in FIG. In FIG. 3, "C", "Si", "Mn", "P", "S", "Cu", and "Ti" are constituents of the welding wire 5, carbon C, silicon Si, manganese Mn, Phosphorus P, sulfur S, copper Cu, and titanium Ti are shown. The numerical value shows the mass% of each substance contained in the welding wire 5. “A”, “B”, and “C” in the “welding wire” column indicate three types of welding wires 5 used in the gas shielded arc welding method of the present embodiment, and all of the welding wires 5 are silicon. The mass% of Si is less than 0.2%. The "conventional" in the "welding wire" column is the welding wire 5 in which the mass% of silicon Si is 0.2% or more.

In FIGS. 4 to 7, the horizontal axis of the upper left and lower left graphs shows the set current Issue (A), and the horizontal axis of the upper right and lower right graphs shows the feeding speed (m / min) of the welding wire 5. There is.
The vertical axis of the graphs on the upper right and upper left of FIG. 4 shows the first peak current (A).
The vertical axis of the lower right and lower left graphs of FIG. 4 shows the first peak time (ms).
The vertical axis of the graphs on the upper right and upper left of FIG. 5 shows the second peak current (A).
The vertical axis of the lower right and lower left graphs of FIG. 5 shows the second peak time (ms).
The vertical axis of the graphs on the upper right and upper left of FIG. 6 shows the average current (A) during the pulse period.
The vertical axis of the lower right and lower left graphs of FIG. 6 shows the time (ms) of the pulse period.
The vertical axis of the graphs on the upper right and upper left of FIG. 7 shows the sum (ms) of the first peak time, the switching time, and the second peak time.
The vertical axis of the lower right and lower left graphs of FIG. 7 shows the frequency fp (Hz) of the pulse current.

The square plot shows the experimental results when the protrusion length of the weld wire 5 is set to 15 mm, and the triangular plot shows the experimental results when the protrusion length of the weld wire 5 is set to 20 mm. In FIGS. 4 to 5, the "A", "B" and "C", and "conventional" plots show the experimental results using the four types of weld wires 5 shown in FIG. Each plot shows a pulse waveform setting value in which the occurrence of spatter is suppressed.

The straight line connecting the circled plots indicates a boundary line that separates the conventional pulse current condition and the pulse current condition according to the present embodiment. At the bottom of each graph, the formula that defines the boundary line is shown.

When the current value of the first peak current is 530 A or more and 700 A or less from the graph in the upper figure of FIG. 4, and the time of the first peak period is 1.2 msec or less from the graph in the lower figure of FIG. 4, silicon Si contained in the welding wire 5 It can be seen that the mass% of the above can be set to less than 0.07% and the occurrence of spatter can be suppressed.

From the graph in the upper figure of FIG. 5, when the current value of the second peak current satisfies the following formula (1) or (2) and the time of the second peak period satisfies the following formula (3) or (4), the weld wire It can be seen that the mass% of silicon Si contained in 5 is set to less than 0.07%, and the occurrence of spatter can be suppressed.
Current value during the second peak period> 0.16 × Set current of welding current Iw Iset (A) +455 ... (1)
Current value during the second peak period> 4 × Feed rate of welding wire 5 (m / min) +455 ... (2)
Time of the second peak period <0.0006 × set current of welding current Iw Iset (A) +0.45 ... (3)
Time of the second peak period <0.015 x feed rate of the welding wire 5 (m / min) + 0.45 ... (4)

From the graph in the upper figure of FIG. 6, when the average current of the pulse period satisfies the following formula (5) or (6) and the time of the pulse period satisfies the following formula (7) or (8), it is included in the welding wire 5. It can be seen that the mass% of silicon Si can be set to less than 0.07% and the generation of spatter can be suppressed.
Average current during pulse period> 0.14 x Welding current set current Issue (A) +350 ... (5)
Average current during pulse period> 3 × Feed rate of welding wire 5 (m / min) +357 ... (6)
Pulse period time <0.036 x welding current set current Issue (A) + 2.45 ... (7)
Time of pulse period <0.09 x feed rate of welding wire 5 (m / min) +2.55 ... (8)

FIG. 7 From the graph in the upper figure, when the total time of the first peak time, the switching time and the second peak time is 1.6 msec or less, the mass% of silicon Si contained in the welding wire 5 is less than 0.07%. It can be seen that the occurrence of spatter can be suppressed.

From the graph in the lower figure of FIG. 7, when the frequency fp of the pulse current satisfies the following formula (9) or (10), the mass% of silicon Si contained in the welding wire 5 is set to less than 0.07%, and spattering occurs. It turns out that it can be suppressed.
Frequency fp> 0.7 × Welding current set current Issue (A) +13.25 ... (9)
Frequency fp> 17.5 × Feeding speed of welding wire 5 (m / min) +35 ... (10)

The frequency fp of the pulse current according to the present embodiment is larger than the conventional standard value obtained by using the set current Issue or the feeding speed as a parameter.

The waveform setting circuit WS of the welding power supply 1 may be configured to output the waveform setting signal Ws that determines the pulse waveform described above, and gas shielded arc welding may be performed using the pulse waveform. Specifically, in the control circuit 12 of the welding power supply 1, the current value of the first peak current is 530 A or more and 700 A or less, the time of the first peak period is 1.2 ms or less, and the current value of the second peak current is the above formula. (1) or (2) is satisfied, the time of the second peak period satisfies the above formula (3) or (4), the average current of the pulse period satisfies the above formula (5) or (6), and the pulse period The time satisfies the above formula (7) or (8), the total time of the first peak time, the switching time and the second peak time is 1.6 ms or less, and the frequency fp of the pulse current is the above formula (9) or The pulse current waveform of the welding current Iw is controlled so as to satisfy (10).

From another point of view, the current values and periods of the first peak current and the second peak current shown in the graphs of FIGS. 4 and 5 are the time of the first peak current and the second peak current and the first peak. It can be seen that the product of the current values during the period and the second peak period with the time average is more than 800 (Amsec).
In the same manner as described above, the waveform setting circuit WS of the welding power supply 1 may be configured to output the waveform setting signal Ws that determines the pulse waveform described above, and gas shielded arc welding may be performed using the pulse waveform. ..

As described above, according to the gas shielded arc welding and the gas shielded arc welding apparatus according to the present embodiment, in pulse arc welding, the generation of silicon oxide slag is suppressed and the welding current of the pulse waveform determined by the pulse waveform set value is suppressed. By supplying Iw, regular droplet migration can be realized and welding can be stabilized. By suppressing the formation of silicon oxide slag, it is possible to suppress the problem of electrodeposition coating defects after welding.

Further, by adjusting the total amount of silicon Si and manganese Mn, which function as deoxidizers, to 1.5 to 2.0% while suppressing the content of silicon Si, it is possible to suppress the generation of blow holes and pits. can.

Further, manganese Mn having a mass% of silicon Si of less than 0.2% by mass and 1.5% by mass or more and 2.0% by mass or less, and titanium having a mass% of 0.05% by mass or more and 0.2% by mass or less. By using the welding wire 5 containing Ti, it is possible to suppress the formation of manganese oxide as slag on the surface of the base metal 4. Therefore, even when the welding wire 5 contains manganese Mn of nearly 2.0% by mass, the problem of electrodeposition coating failure after welding can be effectively suppressed.

In this embodiment, a multi-stage pulse including the first peak period and the second peak period is illustrated, but a gas shield is used by using a pulse current in which the values of the first peak current and the second peak current are the same current values. Arc welding may be performed.

1 Welding power supply 2 Torch 3 Wire feeder 4 Base material 5 Welding wire 11 Power supply circuit 12 Control circuit ID Current detection circuit VD Voltage detection circuit SAV Integrator circuit IS Current setting circuit VS Voltage setting circuit KS External characteristic setting circuit WS Waveform setting circuit FJ waveform generation circuit FC feed rate setting circuit FR feed control circuit WM wire feed motor

Claims (9)

It is a gas shielded arc welding method that is performed by supplying a pulse current to the welding wire.
The weld wire contains less than 0.2% by weight of silicon and contains less than 0.2% by weight.
The pulse current is
It is a multi-stage pulse including a first peak, a second peak, and a transition portion from the first peak to the second peak.
The current value of the first peak is 530 A or more and 700 A or less, and the time of the first peak is 1.2 ms or less.
A gas shielded arc welding method in which the current value of the second peak is smaller than the current value of the first peak. The gas shielded arc welding method according to claim 1, wherein the current value of the second peak satisfies the following formula (1) or (2), and the time of the second peak satisfies the following formula (3) or (4).
Current value of the second peak> 0.16 × Set current of the pulse current (A) +455 ... (1)
Current value of the second peak> 4 × Feeding speed of the welded wire (m / min) +455 ... (2)
Second peak time <0.0006 × set current of the pulse current (A) +0.45 ... (3)
Second peak time <0.015 x feed rate of the welded wire (m / min) + 0.45 ... (4) Claim 1 that the average current of the pulse period including the first peak, the transition portion and the second peak satisfies the following formula (5) or (6), and the time of the pulse period satisfies the following formula (7) or (8). Alternatively, the gas shielded arc welding method according to claim 2.
Average current during the pulse period> 0.14 × Set current of the pulse current (A) +350 ... (5)
Average current during the pulse period> 3 × Feed rate of the welded wire (m / min) +357 ... (6)
Time of the pulse period <0.036 x set current of the pulse current (A) + 2.45 ... (7)
Time of the pulse period <0.09 x feeding speed of the welding wire (m / min) +2.55 ... (8) The gas shielded arc welding method according to any one of claims 1 to 3, wherein the total time of the first peak, the transition portion and the second peak is 1.6 msec or less. Silicon contained in the welding wire is 0.04% by mass or less, and is
The gas shielded arc welding method according to any one of claims 1 to 4, wherein the frequency of the pulse current satisfies the following formula (9) or (10).
Frequency> 0.7 × Set current of the pulse current (A) +13.25 ... (9)
Frequency> 17.5 × Feeding speed of the welded wire (m / min) +35 ... (10) The welding wire is
With manganese of 1.5% by mass or more and 2.0% by mass or less,
The gas shielded arc welding method according to any one of claims 1 to 5, which comprises titanium of 0.05% by mass or more and 0.2% by mass or less. The weld wire contains manganese and
The gas shielded arc welding method according to any one of claims 1 to 6, wherein the sum of the mass% of silicon and the mass% of manganese is 1.5% by mass or more and 2.0% by mass or less. One of claims 1 to 7, wherein the product of the time of the first peak and the second peak and the time average of the current values of the first peak and the second peak is more than 800 (Amsec). The gas shielded arc welding method described in. A gas shielded arc welding device that supplies a pulse current to a welding wire containing less than 0.2% by mass of silicon.
The power supply circuit that outputs the pulse current and
The first peak, the second peak, and the transition part from the first peak to the second peak are included, the current value of the first peak is 530 A or more and 700 A or less, and the time of the first peak is 1.2 ms or less. , A gas shielded arc welding apparatus including a control circuit that controls the output of the power supply circuit so that the pulse current whose current value of the second peak is smaller than the current value of the first peak is output.

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