JP2022012150A - Two-wire welding method - Google Patents

Abstract

To achieve good welding quality by stably maintaining an arc state in a 2-wire welding method that uses a buried arc.SOLUTION: In a two-wire welding method that forms a molten pool 2a by generating an arc 3 between a consumable electrode 1 and a base material 2 and performs welding while inserting a filler wire 6 into a rear half part of the molten pool 2a, the molten pool 2a of a recessed part is formed by placing the arc 3 in a buried arc state and the filler wire 6 is inserted into a peripheral edge part outside the recessed part that does not cause a short circuit between the consumable electrode 1 and the molten pool 2a. When it is determined that the buried arc state has become unstable, an insertion position b of the filler wire 6 is moved backward. That the buried arc state has become unstable is determined from an occurrence of short circuit between the consumable electrode 1 and the molten pool 2a.SELECTED DRAWING: Figure 1

Description

The present invention relates to a two-wire welding method in which an arc is generated between a consumable electrode and a base metal to form a molten pool, and a filler wire is inserted into the latter half of the molten pool and welded.

A two-wire welding method in which an arc is generated between a consumable electrode (hereinafter referred to as a welding wire) and a base metal to form a molten pool, and a filler wire is inserted into the molten pool for welding (see Patent Document 1). Has been known for a long time. In this two-wire welding method, since the molten metal of the filler wire is added to the molten metal of the welding wire, the amount of molten metal increases, and high welding and high speed welding become possible. In particular, when high-speed welding is performed by the two-wire welding method, it is important to contact the filler wire with the molten pool from behind the consumable electrode arc and feed the filler wire in order to prevent the humping bead. This is because when the filler wire is fed into the consumable electrode arc and melted, the molten pool is hardly cooled, and the filler wire cannot suppress the swelling of the latter half of the molten pool, thus suppressing the humping bead. This is because it has no effect. On the other hand, if the filler wire is brought into contact with the latter half of the molten pool of the arc generation part and fed to be melted by the heat of the molten pool, the molten pool is cooled and the latter half of the molten pool is cooled by the filler wire. The portion is suppressed and the formation of the humping bead can be suppressed. Therefore, in the two-wire welding method of the prior art, the filler wire is cooled by contacting the filler wire with the molten pool in a cold state without applying an electric current.

Japanese Unexamined Patent Publication No. 2010-167489

In the two-wire welding method, when the arc generated between the welding wire and the base metal is buried and put into an arc state, deep welding can be obtained and further high welding can be achieved. However, the buried arc state tends to become unstable due to a slight disturbance. In particular, in the two-wire welding method using a buried arc, if the insertion position of the filler wire is not appropriate, there is a problem that the arc state becomes unstable and the welding quality deteriorates.

Therefore, an object of the present invention is to provide a two-wire welding method that can stably maintain an arc state and obtain good welding quality in a two-wire welding method using a buried arc.

In order to solve the above-mentioned problems, the invention of claim 1 generates an arc between the consumable electrode and the base metal to form a molten pool, and welds while inserting the filler wire into the latter half of the molten pool. In the two-wire welding method
The arc is buried to form the molten pool in the recess, and the arc is formed.
The filler wire is inserted into a peripheral edge portion outside the recess where a short circuit between the consumable electrode and the molten pool does not occur.
This is a two-wire welding method characterized by the above.

The invention of claim 2 is
When it is determined that the buried arc state has become unstable, the insertion position of the filler wire is moved backward.
The two-wire welding method according to claim 1, wherein the two-wire welding method is characterized in that.

The invention of claim 3 is
The instability of the buried arc state is determined by the occurrence of a short circuit between the consumable electrode and the molten pool.
The two-wire welding method according to claim 2, wherein the two-wire welding method is characterized in that.

The invention of claim 4 is
The instability of the buried arc state is determined by the fact that the short circuit between the consumable electrode and the molten pool occurs more than a reference number of times per unit time.
The two-wire welding method according to claim 2, wherein the two-wire welding method is characterized in that.

According to the present invention, in the two-wire welding method using a buried arc, the arc state can be stably maintained and good welding quality can be obtained.

It is a schematic diagram of the welded part which shows the 2 wire welding method which concerns on embodiment of this invention. It is a block diagram of the welding apparatus for carrying out the two-wire welding method which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view of a welded portion showing a two-wire welding method according to an embodiment of the present invention. The figure is a side view of the welded portion, and the welding is proceeding to the left as shown by the arrow. Hereinafter, description will be made with reference to the figure.

The welding wire 1 is supplied from the welding torch 4, and an arc 3 is generated between the tip of the welding wire and the base metal 2. The welding wire 1 is fed at a constant speed. Here, the advance angle of the welding torch 4 is 0 °, and the welding wire 1 is fed vertically to the base metal 2. A molten pool 2a is formed in the base metal 2 by this arc 3. The center line indicating the feeding direction of the welding wire 1 is indicated by a alternate long and short dash line, and the point where this center line intersects the surface of the base metal 2 is the welding target position a.

The arc 3 is in a buried arc state. The buried arc state is a state in which the tip of the welding wire 1 has entered the inside of the molten region which is a recess due to the arc force. Therefore, the arc 3 is also generated inside the recess. In order to maintain a stable buried arc state, the welding current Iw set by the welding wire feed rate setting signal Wr in FIG. 2 is a large current value of at least 300 A or more, and the welding voltage setting signal Vr in FIG. 2 is used. It is necessary to set the set welding voltage Vw to an appropriate value that causes a buried arc state. When welding is performed in a buried arc state, it is possible to form a deeply melted melted portion with less spatter generation.

A high set value and a low set value may be provided for the welding voltage setting signal Vr in FIG. 2, and the welding voltage Vw may be vibrated by switching between both values. By doing so, the arc length vibrates, and the buried arc state becomes more stable. The vibration frequency is in the range of 10 to 1000 Hz. The voltage amplitude is set so that the amplitude of the welding current is 50 A or more.

The filler wire 6 is fed in the filler wire guide 7 and is inserted into the insertion position b in the latter half of the molten pool 2a in a contact state. The filler wire 6 is fed at a constant speed. The feeding speed of the filler wire 6 is about 10 to 20% of the feeding speed of the welding wire 1. The distance between the welding target position a and the insertion position b is the wire-to-wire distance Lw (mm). The insertion position b of the filler wire 6 is a peripheral edge portion outside the recess of the molten pool 2a. When the distance Lw between the wires is smaller than the appropriate value, a short circuit occurs between the welding wire 1 and the molten pool 2a, and the arc state becomes unstable. Therefore, the distance Lw between the wires is adjusted to be equal to or larger than the value at which the short circuit does not occur. On the other hand, the distance Lw between the wires is adjusted to be less than a value at which the filler wire 6 can be melted by the heat from the molten pool 2a.

During welding, the shape of the molten pool 2a fluctuates, so that the insertion position b of the filler wire 6 deviates from the proper position, and the buried arc state may become unstable. When it is determined that the buried arc state has become unstable, the insertion position b of the filler wire 6 is automatically moved backward. The buried arc state becomes unstable when the insertion position b of the filler wire 6 enters the recess of the molten pool 2a. Therefore, the unstable state can be eliminated by moving the insertion position b backward.

The instability of the buried arc state can be determined by the occurrence of a short circuit between the welding wire 1 and the molten pool 2a. Further, the instability of the buried arc state can be determined by the fact that the short circuit between the welding wire 1 and the molten pool 2a occurs more than the reference number of times per unit time.

FIG. 2 is a block diagram of a welding device for carrying out the two-wire welding method according to the embodiment of the present invention described above in FIG. The figure shows the case where the consumable electrode type arc welding is DC carbon dioxide arc welding, mag welding or MIG welding. Hereinafter, each block will be described with reference to the figure.

The power main circuit PM receives a commercial power source such as 3-phase 200V (not shown) as an input, and controls the output by inverter control according to the drive signal Dv described later, and weld voltage Vw and welding current Iw for generating arc 3. Is output. Although not shown, the power supply main circuit PM is a primary rectifier circuit that rectifies a commercial power supply, a capacitor that smoothes the rectified direct current, and an inverter circuit that converts the smoothed direct current into high-frequency alternating current according to the above drive signal Dv. It is equipped with a high-frequency transformer that steps down the high-frequency alternating current to an appropriate voltage value to generate an arc 3, a secondary rectifier circuit that rectifies the stepped-down high-frequency alternating current, and a reactor that smoothes the rectified direct current.

The welding wire 1 is fed in the welding torch 4 by the rotation of the welding wire feeding roll 5 coupled to the welding wire feeding motor WM, and is fed from the power supply main circuit PM described above via a feeding chip (not shown). The power is supplied and an arc 3 is generated between the base material 2 and the base metal 2. A welding voltage Vw is applied between the welding wire 1 and the base metal 2, and a welding current Iw is energized.

The filler wire 6 is fed in the filler wire guide 7 by the rotation of the filler wire feeding roll 8 coupled to the filler wire feeding motor FM, and is inserted into the molten pool 2a formed by the arc 3. The filler wire 6 is inserted into the insertion position b described above in FIG. 1 in a state of being in contact with the molten pool 2a.

The moving mechanism 9 is a motor for moving the insertion position b of the filler wire 6 backward by a predetermined distance each time the buried arc state determination signal Ad reaches the high level for a short time by inputting the buried arc state determination signal Ad described later. It is a mechanism including. Therefore, each time the buried arc state determination signal Ad reaches the High level for a short time, the distance Lw between the wires increases by a predetermined distance. As the above mechanism, a mechanism for converting the rotary motion of the motor into a linear motion by a slide crank mechanism, a mechanism for converting the rotary motion of the motor into a swing motion by a crank and a swing wheel, and the like have been conventionally used. .. The above predetermined distance is, for example, 1 mm.

The welding voltage detection circuit VD detects the above welding voltage Vw and outputs a welding voltage detection signal Vd.

The welding voltage setting circuit VR outputs a predetermined welding voltage setting signal Vr. The welding wire feeding speed setting circuit WR outputs a predetermined welding wire feeding speed setting signal Wr. The feeding speed of the welding wire 1 is set by the welding wire feeding speed setting signal Wr, and the value of the welding current Iw is determined. The values of the welding voltage setting signal Vr and the welding wire feeding speed setting signal Wr are set so as to be in a stable buried arc state as described above in FIG.

The voltage error amplification circuit EV amplifies the error between the above-mentioned welding voltage setting signal Vr and the above-mentioned welding voltage detection signal Vd, and outputs a voltage error amplification signal Ev.

The drive circuit DV receives the voltage error amplification signal Ev as an input, performs PWM modulation control based on this signal, and based on the result, drives the drive signal Dv for driving the inverter circuit in the power supply main circuit PM. Is output. With this circuit, the welding device becomes a power source with constant voltage characteristics.

The welding wire feeding control circuit WC sends a welding wire feeding control signal Wc for feeding the welding wire 1 at a feeding speed corresponding to the value of the welding wire feeding speed setting signal Wr. Output to the feed motor WM.

The filler wire feeding speed setting circuit FR outputs a predetermined filler wire feeding speed setting signal Fr.

The filler wire feed control circuit FC sends the filler wire feed control signal Fc for feeding the filler wire 6 at a feed rate corresponding to the value of the filler wire feed rate setting signal Fr. Output to the feed motor FM.

The short-circuit discrimination circuit SD receives the above welding voltage detection signal Vd as an input, and when this value is equal to or less than the short-circuit discrimination value (about 10V), it determines that the welding wire 1 and the molten pool 2a are in a short-circuited state and is at a high level. The short-circuit determination signal Sd is output.

The buried arc state determination circuit AD receives the above short-circuit identification signal Sd and the above welding voltage detection signal Vd as inputs, selects one from the following 1) to 3) and performs processing, and the buried arc state determination signal Ad. Is output.
1) Every time the short-circuit discrimination signal Sd reaches the high level, the buried arc state discrimination signal Ad, which becomes the high level for a short time, is output. The state in which a short circuit occurs is a sign that the buried arc state becomes unstable.
2) The number of times the short-circuit discrimination signal Sd changes to the High level is detected for each unit time, and when the number of short-circuits exceeds a predetermined reference number, the buried arc state discrimination signal Ad which becomes the High level for a short time is output. For example, the unit time is 100 ms, and the reference number of times is three times. A state in which the number of short circuits per unit time exceeds the reference number is a sign that the buried arc state becomes unstable.
3) When the fluctuation range of the welding voltage detection signal Vd becomes equal to or larger than the reference value, the buried arc state determination signal Ad, which becomes the High level for a short time, is output. A state in which the fluctuation range of the welding voltage exceeds the reference value is a sign that the buried arc state becomes unstable.

According to the above-described embodiment, in the two-wire welding method in which an arc is generated between the consumable electrode and the base metal to form a molten pool, and the filler wire is inserted into the latter half of the molten pool and welded. Is buried in an arc state to form a molten pool of the recess, and the filler wire is inserted into the peripheral edge outside the recess where the short circuit between the consumable electrode and the molten pool does not occur. The buried arc state tends to become unstable due to a slight disturbance. In particular, in the two-wire welding method using a buried arc, if the insertion position of the filler wire is not appropriate, the arc state becomes unstable and the welding quality deteriorates. By inserting the filler wire into the peripheral edge portion outside the recess where the short circuit between the consumable electrode and the molten pool does not occur as in the present embodiment, it is possible to suppress the buried arc state from becoming unstable. This is because if the filler wire is not inserted properly, a short circuit will occur. Therefore, in the present embodiment, in the two-wire welding method using a buried arc, the arc state can be stably maintained and good welding quality can be obtained.

Further, according to the present embodiment, it is preferable to move the insertion position of the filler wire to the rear when it is determined that the buried arc state has become unstable. During welding, the shape of the molten pool fluctuates, so that the insertion position of the filler wire deviates from the proper position, and the buried arc state may become unstable. When it is determined that the buried arc state has become unstable, the insertion position of the filler wire is automatically moved backward. The buried arc state becomes unstable when the insertion position of the filler wire enters the recess of the molten pool. Therefore, the unstable state can be eliminated by moving the insertion position backward.

Further, according to the present embodiment, it is determined that the buried arc state becomes unstable by the short circuit between the consumable electrode and the molten pool. By doing so, it is possible to automatically determine that the buried arc state has become unstable and automatically move the insertion position of the filler wire to the rear. Therefore, the insertion position of the filler wire can always be maintained at an appropriate position without performing complicated operations.

Further, according to the present embodiment, it is determined that the buried arc state becomes unstable by the fact that the short circuit between the consumable electrode and the molten pool occurs more than the reference number of times per unit time. By doing so, it is possible to automatically determine that the buried arc state has become unstable and automatically move the insertion position of the filler wire to the rear. Therefore, the insertion position of the filler wire can always be maintained at an appropriate position without performing complicated operations.

1 Welding wire (consumable electrode)
2 Base material 2a Molten pond 3 Arc 4 Welding torch 5 Welding wire feeding roll 6 Filler wire 7 Filler wire guide 8 Filler wire feeding roll 9 Moving mechanism a Welding aim position AD Buried arc state discriminating circuit Ad Buried arc state discriminating signal b Filler wire insertion position DV drive circuit Dv drive signal EV voltage error amplification circuit Ev voltage error amplification signal FC filler wire feed control circuit Fc filler wire feed control signal FM filler wire feed motor FR filler wire feed speed setting circuit Fr filler Wire feeding speed setting signal Iw Welding current Lw Wire distance PM Power supply main circuit SD Short circuit discrimination circuit Sd Short circuit discrimination signal VD Welding voltage detection circuit Vd Welding voltage detection signal VR Welding voltage setting circuit Vr Welding voltage setting signal Vw Welding voltage WC Welding Wire feeding control circuit Wc Welding wire feeding control signal WM Welding wire feeding motor WR Welding wire feeding speed setting circuit Wr Welding wire feeding speed setting signal

Claims (4)

In a two-wire welding method in which an arc is generated between a consumable electrode and a base metal to form a molten pool, and a filler wire is inserted into the latter half of the molten pool while welding.
The arc is buried to form the molten pool in the recess, and the arc is formed.
The filler wire is inserted into a peripheral edge portion outside the recess where a short circuit between the consumable electrode and the molten pool does not occur.
A two-wire welding method characterized by this. When it is determined that the buried arc state has become unstable, the insertion position of the filler wire is moved backward.
The two-wire welding method according to claim 1. The instability of the buried arc state is determined by the occurrence of a short circuit between the consumable electrode and the molten pool.
2. The two-wire welding method according to claim 2. The instability of the buried arc state is determined by the fact that the short circuit between the consumable electrode and the molten pool occurs more than a reference number of times per unit time.
2. The two-wire welding method according to claim 2.

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