JPH0747474A - Horizontal one layer/plural passes welding method - Google Patents

Abstract

PURPOSE:To prevent sagging of a molten pool of each pass, so that a weld besad of a satisfactory shape as a whole can be obtained. CONSTITUTION:With respect to a horizontal groove 2, in the case by driving it into plural passes in the vertical direction, each pass is welded a one-layer portion each, respectively in order from the pass of the lower side, at least the lower pass is welded by a short circuit arc welding torch 15 for short- circuiting and transferring a droplet 11 from a welding wire to the groove 2, and at least the uppermost pass is welded by a pulse arc welding torch 16 by which the droplet 11 is sprayed and transferred from the welding wire 4 to the groove 2. Also, by a molten pool 12' which is scarcely sagged, formed by the short circuit welding torch 15, a molten pool 12 by the pulse arc welding torch 16 is supported, and sagging of the molten pool 12 by the pulse arc welding torch 16 is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal single-layer multi-pass welding method.

[0002]

2. Description of the Related Art FIG. 10 shows a horizontal single-layer welding method.

In the figure, 1 is a weld base metal, and 2 is a groove formed laterally on the weld base metal 1. 3 is a welding torch for supplying the welding wire 4 to the groove 2, 5 is a feeding roller for feeding the welding wire 4 to the welding torch 3, and 6 is a groove 2 provided at the tip of the welding torch 3. A gas nozzle for injecting the shield gas 7 toward the target, and a power supply tip 8 provided inside the welding torch 3 for supplying power to the welding wire 4.

Reference numeral 9 is a welding power source for generating an arc 10, which is connected between the welding base material 1 and the power feeding tip 8.
Reference numeral 1 is a droplet formed by melting the welding wire 4 by the heat of the arc 10, and 12 is a molten pool formed in the groove 2.

When performing horizontal welding, first, the shield gas 7 is injected from the gas nozzle 6 formed at the tip of the welding torch 3 toward the groove 2 formed in the welding base material 1 to form the groove 2 Seal from the atmosphere.

In this state, by feeding the welding wire 4 to the welding torch 3 by using the feeding roller 5, the welding wire 4 is fed from the welding torch 3 to the groove 2.
When a voltage is applied between the welding base material 1 and the power feed tip 8 by the welding power source 9, an arc 10 is generated between the welding base material 1 and the tip of the welding wire 4, and the heat of the arc 10 causes the welding wire to move. 4 and the groove 2 are heated and melted.

The droplet 11 formed by melting the tip of the welding wire 4 is transferred from the tip of the welding wire 4 to the groove 2 by the action of surface tension, electromagnetic pinch force, arc force or the like. , A molten pool 12 is formed in the groove 2, and the molten pool 12 is solidified into a welding bead,
The groove 2 is welded.

When the width of the groove 2 is wide in the vertical direction, as shown in FIGS. 11 (a) (b) (c),
The groove 2 is divided into a plurality of passes in the vertical direction, and welding is performed sequentially from the lower pass.

In FIG. 11, reference numeral 13 denotes a weld bead formed by solidifying the molten pool 12, and FIG. 11 (a) shows the case of 2 passes, FIG. 11 (b) shows the case of 3 passes, and FIG. (C)
Indicates the case of four passes. There are also cases where there are more than 5 passes.

Here, when the welding method is classified according to the transfer form of the droplet 11 when the droplet 11 is transferred from the tip of the welding wire 4 to the groove 2, the droplet 11 is spray transferred (in the form of particles). The pulse arc welding method in which the droplets 11 are sprayed) and the short-circuit arc welding method in which the droplets 11 are short-circuited (the droplets 11 are extended so as to short-circuit the welding wire 4 and the groove 2). Yes, the pulse arc welding method is mainly used for MAG welding that uses a mixed gas of carbon dioxide gas and argon gas as the shield gas 7, and the short-circuit arc welding method is mainly used for carbon dioxide welding that uses carbon dioxide gas as the shield gas. Has been adopted.

In the horizontal single-layer multiple-pass welding method described above, the pulse arc welding method, which is capable of forming a beautiful molten pool 12 by spray transfer of droplets 11, is usually used for all passes. To be done.

[0012]

However, the above-mentioned conventional lateral single-layer multiple-pass welding method has the following problems.

That is, in the lateral single-layer multiple-pass welding method,
All the passes were welded by the pulse arc 10 welding method, which is capable of forming a beautiful molten pool 12 by spray transfer of the droplets 11. However, in the pulse arc 10 welding method, the molten pool 12 is Since the molten pool 12 has a drawback that it easily drips, as shown in FIGS. 11A, 11B, and 11C, the molten pools 12 of the respective passes are vertically overlapped in a dripping state. A certain weld bead 13 was formed, which was a cause of welding defects.

In view of the above-mentioned circumstances, the present invention provides a lateral single-layer multiple-pass welding method in which the molten pool in each pass is prevented from dripping and a weld bead having a good shape as a whole can be obtained. The purpose is.

[0015]

According to the present invention, when a transverse groove is divided into a plurality of passes in the vertical direction, and each pass is welded by one layer in order from the lower pass. , At least the bottom path is welded by a short-circuit arc welding torch that short-circuits the droplet from the welding wire to the groove,
The present invention relates to a lateral single-layer multiple-pass welding method characterized in that at least the uppermost pass is welded by a pulse arc welding torch in which droplets are spray-transferred from a welding wire to a groove.

[0016]

The operation of the present invention is as follows.

When the horizontal groove is divided into a plurality of passes in the vertical direction and each pass is welded by one layer in order from the lower pass, the number of welds in the horizontal one-layer multiple pass welding is small. Weld the bottom path with a torch for short-circuit arc welding that transfers the droplets from the welding wire to the groove in a short circuit,
Weld at least the uppermost path with a pulse arc welding torch in which droplets are spray transferred from the welding wire to the groove.

Then, since the melt pool formed by the short-circuit arc welding is less likely to sag, the melt pool formed by the pulse arc welding is supported, so that the melt pool formed by the pulse arc welding is prevented from dripping, and the welding pool as a whole has no dripping. Beads can be formed.

Further, since the formed weld bead covers most of the surface with the weld bead formed by pulse arc welding of the uppermost layer, it is possible to form a beautiful weld bead as a whole.

[0020]

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

1 to 7 (a) (b) (c) (d),
It is the first embodiment of the present invention and shows the case of performing two-pass welding.

In the figure, 1 is the welding base metal, 2 is the welding base metal 1
A groove 5 formed laterally on the roller 5, a feeding roller for feeding the welding wire 4, 11 a droplet formed by melting the welding wire 4 by the heat of the arc 10, and 12 and 12 'formed on the groove 2. The molten pool 13 is a molten bead formed in the groove 2 by solidifying the molten pools 12 and 12 ′.

Further, 14 is a welding advancing direction.

A short-circuit arc welding torch 15 is provided toward the groove 2, and a pulse arc welding torch 16 is provided above the short-circuit arc welding torch 15 so as to be shifted downstream in the welding advancing direction 14 and both torches are provided. A plurality of electrode torches 20 are configured by fixing 15 and 16 through a clamp 17 for adjusting a gap to adjust a gap 18 in a vertical direction of a welding wire 4 and a gap 19 in a welding advancing direction 14 so as to be integrated with each other. .

A short-circuit arc welding gas nozzle for injecting a short-circuit arc welding shield gas 21 such as carbon dioxide gas or a mixed gas of carbon dioxide gas and argon gas toward the groove 2 at the tip of the short-circuit arc welding torch 15. 22 is provided,
A pulse arc welding gas nozzle 24 for injecting a shield gas 23 for pulse arc welding such as a mixed gas of argon gas and carbon dioxide gas toward the groove 2 is provided at the tip of the pulse arc welding torch 16.

Inside each of the torches 15 and 16, there are provided feeding tips 25 for feeding electricity to the welding wire 4.
A power supply 26 for short-circuit arc welding such as a DC constant voltage power supply is connected between the welding base material 1 and the power supply tip 25 of the torch 15 for short-circuit arc welding, and a power supply tip for the welding base material 1 and the torch 16 for pulse arc welding. A pulse arc welding power source 27 such as a DC pulse power source is connected between the power source 25 and the terminal 25.

In FIG. 4, 28 is an arc period of the short-circuit arc welding power source 26, and 29 is a short-circuit period of the short-circuit arc welding power source 26.

Further, in FIG. 6, 30 is a base current period of the pulse arc welding power source 27, and 31 is a pulse current period 31 of the pulse arc welding power source 27.

Prior to welding, the interval adjusting clamp 17 is used to adjust the interval between the short-circuit arc welding torch 15 and the pulse arc welding torch 16 of the multi-electrode torch 20 as follows.

That is, the vertical gap 18 between the welding wire 4 of the short-circuit arc welding torch 15 and the pulse arc welding torch 16 is 3 mm or more, and the gap 19 of the welding wire 4 in the welding advancing direction 14 is about 15 to 20 mm. Within the range.

Further, in order to sufficiently obtain the penetration of the corner portion of the groove 2, a multi-electrode torch is provided for the groove 2 so that the distance between the wall of the groove 2 and the side surface of the welding wire 4 is 3 mm or less. Place 20.

When performing horizontal one-layer two-pass welding, first, the welding base metal 1 is welded from the short-circuit arc welding gas nozzle 22 formed at the tip of the short-circuit arc welding torch 15.
By injecting a shield gas 21 for short-circuit arc welding such as carbon dioxide gas or a mixed gas of carbon dioxide gas and argon gas toward the groove 2 formed in the groove 2, the groove 2 is sealed from the atmosphere and, at the same time, a pulse arc is formed. A pulse arc welding shield gas 23 such as a mixed gas of carbon dioxide gas and argon gas is directed from the gas nozzle 24 for pulse arc welding formed at the tip of the welding torch 16 toward the groove 2 formed in the welding base material 1. The groove 2 is sealed from the atmosphere by injecting.

In this state, the feeding wire 5 is used to feed the welding wire 4 to both torches 15 and 16 so that the welding wire 4 moves from each welding torch 15 and 16 toward the groove 2.
To supply.

Then, when a voltage is applied between the welding base material 1 and the power supply tip 25 of the torch 15 for short-circuit arc welding by a short-circuit arc welding power source 26 such as a DC constant voltage power source,
An arc 10 is generated between the welding base material 1 and the tip of the welding wire 4 of the torch 15 for short-circuit arc welding. At this time, FIG.
As shown in, the current waveform is controlled.

When a voltage is applied between the welding base metal 1 and the power feed tip 25 of the pulse arc welding torch 16 by a pulse arc welding power source 27 such as a DC pulse power source,
An arc 10 is generated between the welding base material 1 and the tip of the welding wire 4 of the torch 16 for pulse arc welding. At this time, a pulse current as shown in FIG. 6 is applied.

Then, in the short-circuit arc welding torch 15, as shown in FIG. 5 (a), in the initial period a of the arc period 28 in FIG. 4, the heat of the arc 10 preheats the tip of the welding wire 4 and the groove 2. Is started, and by the end b of the arc period 28, the tip of the welding wire 4 and the groove 2 are sufficiently preheated, and droplets 11 are formed as shown in FIG. 5B.

At the time when the droplet 11 is formed to some extent,
The welding current is increased to enter the short circuit period 29 of FIG. 4, and at the initial stage c of the short circuit period 29, as shown in FIG. 5C, the droplet 11 formed on the tip of the welding wire 4 is located on the groove 2 side. And the welding wire 4 and the groove 2 are short-circuited (short-circuit transition), and the molten pool 12 ′ is formed in the groove 2.

Then, at the end d of the short circuit period 29,
As shown in FIG. 5D, the droplet 11 is divided by the electromagnetic pinch effect by the welding current, and the short circuit state is eliminated,
The welding current is reduced, and the arc period 28 in which the arc 10 is generated between the welding wire 4 and the groove 2 is returned again, and the above is repeated thereafter.

The short-circuit arc welding performed in this manner is characterized in that the molten pool 12 'is unlikely to drip.

On the other hand, in the pulse arc welding torch 16, at the initial stage a of the base current period 30 of FIG.
As shown in FIG. 7, the preheating of the welding wire 4 tip and the groove 2 is started by the base current, and the welding wire 4 tip and the groove 2 are sufficiently preheated by the end b of the base current period 30. As shown in (b), a droplet 11 is formed.

At the time when the preheating was sufficiently performed, the welding current was rapidly increased to the pulse current period 31 of FIG.
At the initial c of the pulse current period 31, as shown in FIG. 7 (c), the droplet 11 formed on the tip of the welding wire 4 was rapidly grown, and was grown by the end d of the pulse current period 31. As shown in FIG. 7 (d), the droplet is made into particles by the electromagnetic pinch force or the like by the pulse current and is transferred to the groove 2 side in a spray form (spray transfer), and the molten pool 12 is transferred to the groove 2. Formation, and the above is repeated thereafter.

In the pulse arc welding thus performed, the molten pool 12 is liable to sag, but the beautiful weld bead 1 is formed.
3 can be formed.

Then, the melt pools 12, 12 'formed by the short-circuit arc welding and the pulse arc welding are solidified to form the welding beads 13, so that the groove 2 is welded.

A higher welding current is generally applied to pulse arc welding than to short-circuit arc welding.

As described above, according to the present invention, the short circuit arc welding torch 15 is used to perform the short circuit arc welding in which the molten pool 12 'is unlikely to drip to the lower path.
With a slight delay to short-circuit arc welding, a pulse arc welding torch 16 is used to melt pool 12 to the upper pass.
As shown in FIG. 2, the molten pool 1 formed by the preceding short-circuit arc welding is performed by performing pulse arc welding capable of forming a beautiful weld bead 13 that easily drops.
The weld bead 13 immediately after the solidification of 2'supports the molten pool 12 by pulse arc welding, so that the drooling of the molten pool 12 by pulse arc welding is prevented.

Moreover, by setting the distance 19 between the welding wires 4 of the short-circuit arc welding torch 15 and the pulse arc welding torch 16 in the welding advancing direction 14 to 20 mm or less, the molten pool 12 can be formed as shown in FIG. The molten pools 12 connected to one another are restrained from each other, and the gap 19 between the welding wires 4 in the welding advancing direction 14 is set to 15 mm or more. Since the molten pool 12 is dispersed in an elongated shape so that the molten pool 12 is not concentrated too much, the sagging of the molten pool 12 due to pulse arc welding is prevented.

Further, by setting the vertical gap 18 between the welding wires 4 to 3 mm or more, it is possible to prevent the melt pools 12 connected together from concentrating too much in one vertical position. The drooling of the molten pool 12 due to arc welding is prevented.

Therefore, as shown in FIGS. 1 and 3, the groove 2
The smooth welding bead 13 is formed on most of the surface by pulse arc welding, and a good welding bead 13 can be obtained.

In FIG. 3, the multi-electrode torch 20 is symbolized and abbreviated.

FIG. 8 shows a second embodiment of the present invention. When the groove 2 is welded in 3 passes, the bottom pass is short-circuit arc welding and the top pass is pulse arc welding. In FIG. 8A, the intermediate path is welded by short-circuit arc welding, and in FIG. 8B, the intermediate path is welded by pulse arc welding.

Even in this case, the same operation and effect as those of the above-mentioned embodiment can be obtained.

FIG. 9 shows a third embodiment of the present invention. When welding the groove 2 in four passes, the bottom pass is short-circuit arc welding and the top pass is pulse arc welding. In FIG. 9 (a), the second pass is welded by pulse arc welding, and the third pass is welded by short-circuit arc welding.
In (b), the second pass is welded by short-circuit arc welding, and the third pass is welded by pulse arc welding.

Even in this case, the same operation and effect as those of the above-mentioned respective embodiments can be obtained.

The present invention is not limited to the above-described embodiment, short-circuit arc welding is not limited to carbon dioxide welding, pulse arc welding is not limited to MAG welding, and horizontal direction of 5 passes or more. It is needless to say that the present invention can be applied to welding and that various changes can be made without departing from the scope of the present invention.

[0055]

As described above, the horizontal orientation 1 of the present invention
According to the layer multiple-pass welding method, it is possible to obtain an excellent effect that the molten pool in each pass is prevented from dripping and a weld bead having a good shape as a whole can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic side view of a first embodiment of the present invention.

FIG. 2 is a schematic view of FIG. 1 viewed from a II-II direction.

FIG. 3 is a diagram showing a state of a welding bead in FIG.

FIG. 4 is a diagram showing a state of welding current applied in the case of short-circuit arc welding.

5A is a diagram showing a state of droplets at the beginning of an arc period, FIG. 5B is a diagram showing a state of droplets at the end of an arc period, and FIG. 5C is a diagram showing droplets at the beginning of a short circuit period. FIG. 3D is a diagram showing the state of transfer, and FIG. 3D is a diagram showing the state of droplet separation at the end of the short circuit period.

FIG. 6 is a diagram showing a state of welding current applied in the case of pulse arc welding.

7A is a diagram showing a state of droplets at the beginning of a base period, FIG. 7B is a diagram showing a state of droplets at the end of a base period, and FIG. 7C is a diagram showing droplets at the beginning of a pulse period. FIG. 3D is a diagram showing the state of growth, and FIG. 3D is a diagram showing the state of droplet transfer at the end of the pulse period.

FIG. 8 is a second embodiment of the present invention, in the case where the groove is welded in three passes, (a) is a diagram showing a state where the intermediate pass is welded by short-circuit arc welding, and (b) is an intermediate stage. It is a figure which shows a mode that a path is welded by pulse arc welding.

FIG. 9 is a third embodiment of the present invention, in the case where the groove is welded in four passes, (a) shows that the second pass is welded by pulse arc welding and the third pass is short-circuited arc welding. FIG. 6B is a diagram showing a state of welding with the second pass by short-circuit arc welding and a state of welding with a third pass by pulse arc welding.

FIG. 10 is a schematic side view of lateral single layer welding.

11 (a) is a schematic view of lateral one-layer two-pass welding seen from the side, FIG. 11 (b) is a schematic view of lateral one-layer three-pass welding seen from the side, and FIG. 11 (c) is a lateral one-layer four. It is the schematic which looked at path welding from the side.

[Explanation of symbols]

 2 groove 4 welding wire 11 droplet 15 torch for short-circuit arc welding 16 torch for pulse arc welding

Claims (1)

[Claims] 1. When a horizontal groove is divided into a plurality of passes in the vertical direction and each pass is welded by one layer in order from the bottom pass, at least the bottom pass is welded. Characterized by welding with a short-circuit arc welding torch that transfers the droplets from the wire to the groove in a short circuit, and at least the uppermost path with a torch for pulse arc welding in which droplets are spray-transferred from the welding wire to the groove. Sideways 1
Layer multiple pass welding method.