JPH0729205B2 - High-speed gas shield arc welding method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a high-speed gas shielded arc welding method which has excellent welding workability and can obtain an excellent welded portion, and more particularly, two or more flux-cored wires as electrodes. It relates to multi-electrode gas shielded arc welding using.

[Prior Art] In the recent welding field, the application of the gas shielded arc welding method has been remarkably increasing for the purpose of improving welding efficiency and rationalizing welding work.

Particularly in the construction sector for ships or bridges, the carbon dioxide arc welding method using a titania-based flux-cored wire is rapidly spreading. In the welding work in these departments, the ratio of horizontal fillet welding line to the total welding length is extremely high, and how to perform horizontal fillet welding efficiently and at high speed determines the welding efficiency of the entire welded structure. It is the biggest challenge to raise.

In addition, in departments that target machines or steel frames, a major challenge is to increase the welding speed in down fillet welding or downward butt welding (particularly achieving a welding speed of 60 cm / min or more) in addition to horizontal fillet welding. Has become.

Under these problems, high-speed welding methods mainly consisting of the submerged arc welding method and the gas shielded arc welding method have been actively studied.

Of these, the submerged arc welding method is capable of high-current welding using large-diameter wires, so it is widely used as a high-efficiency welding method for thick plates in shipbuilding, heavy equipment, and a number of fields, and as a means for high-speed welding, For example, JP-B-56-52672 and JP-A-60-1
No. 48679 has been proposed. The former aims at speeding up by specifying welding current and voltage, and the latter aims at speeding up of submerged arc welding by applying electromagnetic propulsion force by a moving magnetic field to molten metal.

On the other hand, also in the high-speed gas shield arc welding method, as means for increasing the speed, for example, Japanese Patent Publication No. 58-13269 and Japanese Patent Laid-Open No.
No. 2678 is proposed. In the former, in order to improve the quality and efficiency of DC gas shielded arc welding, a small diameter wire is used for the first electrode and a large diameter wire is used for the second electrode, and the distance between the electrodes is 100 mm or more. The latter uses one or more groups of electrodes equipped with a feeding tip capable of feeding two or more welding wires with one feeding motor.
It is 3.2 mm in length and is welded at a high current of 1000 to 2500 A to increase the speed.

[Problems to be Solved by the Invention] However, in the case of the submerged arc welding method, the welding head becomes large because a flux dispersion and recovery mechanism is essential.

The control of flux composition, particle size, water content, etc. is complicated and the automation mechanism becomes complicated.

Thermal distortion increases as the welding heat input increases.

Due to the above problems, recently, improved research based on the gas shielded arc welding method has become mainstream.

Further, the gas shielded arc welding method, which has been proposed so far, is insufficient and has the following problems. That is, in the case of the gas shielded arc welding method, there are a single electrode method and a multi-electrode method, but speeding up (especially 60 cm / min or more) is limited in the following points.

Single electrode method When a thin wire is used, the bead appearance and shape are significantly deteriorated (undercuts and convex beads are generated).

When a large-diameter wire is used, the arc length is shorter than that of a small-diameter wire, so the range of welding conditions such as welding speed is narrowed.

The amount of welding is small and the required leg length cannot be obtained.

Multi-electrode method (generally the distance between the electrodes is 100 mm or more) The bead shape becomes poor (two-step beads and convex beads are generated).

Since high accuracy is required at the target position of each wire, it is difficult to set it.

The welding head becomes complicated.

Due to these difficulties, it has not been generalized by any method.

As described above, in horizontal or downward fillet welding and downward butt welding using shield gas, both the single electrode method and the multiple electrode method have advantages and disadvantages, and it is not possible to satisfy both welding efficiency and weld joint performance. It is possible.

The present invention has been made by paying attention to such a situation, and has high-speed welding that combines the advantages of the single-electrode method that the allowable range of the wire target position is wide and the advantages of the multi-electrode method that the amount of welding is large. The purpose is to realize the law.

That is, the present invention has solved the disadvantages and drawbacks of the prior art in high-speed welding of 60 cm / min or more, a bead shape, appearance, good welding workability such as arc stability, and an excellent weld portion without welding defects. It is an object of the present invention to provide a high-speed gas shield arc welding method that can be obtained at high speed.

[Means for Solving the Problems] The high-speed gas shielded arc welding method according to the present invention that has achieved the above object is a multi-electrode gas shielded arc welding method in which a metal-based flux-cored wire is attached to the preceding first electrode. The gist thereof exists when a titania-based flux-cored wire is used for at least the final electrode of the following electrodes.

[Operation] The operation of the present invention will be described below based on the findings leading to the present invention.

The present inventors, in order to establish a multi-electrode gas shielded arc welding method that can respond to the request for high-speed welding, first in horizontal fillet welding, set the target welding speed to 150 cm / min or more, and the above-mentioned welding With the aim of obtaining the leg length (generally 4.0 mm or more) required for the fillet welds of structures, we conducted preliminary experiments to find an improvement direction that can approach these goals as much as possible. The result is as follows.

The flux-cored wire is the most preferable wire for ensuring good welding workability (spatter, arc stability, bead shape, bead appearance, etc.) in high-speed welding.

Further, the welding workability is greatly affected by the type of flux used, and in the high-speed welding targeted by the present invention, a metal-based flux-cored wire is used for the leading first electrode, and at least the last of the following electrodes is used. It is essential to use a titania-based flux-cored wire for the electrode.

Here, the metal-based flux-containing wire is a wire containing iron powder or iron alloy powder as the main component of the flux. The titania-based flux-cored wire is a wire containing rutile (TiO ₂ ) as the main component of the flux.

The present inventor has completed the present invention based on the above new findings.

The above was found by horizontal fillet welding, but the same was true for downward fillet welding and downward butt welding.

In the present invention, a metal-based flux-cored wire and a titania-based flux-cored wire are applied, and examples of the composition of the flux to be filled in the wire sheath are as follows.

・ Metal-based flux-cored wire ・ Metal powder: 30-80 wt% ・ Arc stabilizer: 1-20 wt% ・ Deoxidizer: 10-40 wt% Flux rate: 10-20 wt% ・ Titania-based flux-cored wire ・ Casting agent: 20 to 60 wt% (however, TiO _2: 10~55wt%, other slag agent: 5-50 wt
%) ・ Metallic powder: 5 to 40 wt% ・ Arc stabilizer: 1 to 15 wt% ・ Deoxidizer: 10 to 40 wt% Flux rate: 10 to 20 wt% The above composition is an example, and other components may be added as necessary. You may add and change a composition ratio.

In the present invention, it is essential to use a metal-based flux-cored wire for the leading electrode and a titania-based flux-cored wire for the trailing electrode. That is, since the metal-based flux-cored wire has a small amount of slag generation, if it is used as the first electrode, the spread of the pool of the trailing electrode is not hindered by the slag of the first electrode, and the stable migration of the pool is achieved. Is sufficiently secured, it is possible to maintain a good bead shape and appearance. In addition, since the titania-based flux-cored wire has a large amount of slag containing TiO ₂ as a main component, the slag covers the entire surface of the bead, and the appearance, shape, familiarity of the toe, etc. can be well maintained. Therefore,
If a titania-based flux-cored wire is used as the trailing electrode, the bead shape and appearance can be kept good.

[Description of Embodiments] (Claim 2) The diameter of the metal-based flux-cored wire and the titania-based flux-cored wire is preferably 1.4 mm or more.

In the present invention, the diameter of the wire is not limited, but when both wires having a diameter of less than 1.4 mm are used,
When welding is performed at a welding speed of cm / mm or more, the wire diameter is 1.4.
The bead shape and appearance are inferior compared to the case where a product with a size of mm or more is used.

However, when the diameter of both wires is 1.4 mm or more, even at a welding speed of 150 cm / min or more, the same bead shape as when welding with a wire of 1.4 mm or less and a welding speed of 150 cm / min or less is obtained. It is possible to secure the amount of welding necessary to obtain the target leg length while maintaining the appearance.

(Claims 3 and 4) Further, it is preferable that the preceding two electrodes have the same polarity, and it is more preferable that the distance between the electrodes is 50 mm or less.

When the polarity is DC-DC or AC-AC and the wire with diameter of 1.4mm or more is used with welding current of 3000A or more, the distance between electrodes is 5
Arc interference may occur at 0 to 100 mm, which adversely affects workability. However, the distance between the electrodes is 50 mm
In the following, the arc interference is alleviated and the welding workability is in a state without any particular problem.

Regarding this arc interference, when the gap between the electrodes is gradually shortened from the normal 100 mm in tandem welding, arc interference gradually occurs, but we obtained the knowledge that the phenomenon tends to subside when the distance is less than a certain distance. In this embodiment 50
It is specified below mm.

Regarding the polarity of the electrodes, the polarity of the preceding two electrodes is DC-A
In the case of C and AC-DC, there is a tendency that spatter increases or arc instability phenomenon occurs. On the other hand, DC-DC, AC-AC
Then, such a phenomenon does not occur, and better workability can be obtained. A particularly preferred polarity is DC-DC.

[Example] Example 1 Flux-cored wire for welding shown in Table 1 (wire diameter 1.
High-speed gas shield arc welding was performed under the welding conditions shown in Table 2. The welding results are shown in Table 3.
In Table 1, the wire symbols a, b, and c are respectively
Metal-based flux-cored wire, titania-based flux-cored wire, lime-titania-based flux-cored wire, Fe-Mn 80% Mn, Fe-Si 40% Si, Fe-Ti 4
The composition is 0% Ti.

○, △, × in the test results of Table 3, respectively,
Good, slightly inferior, inferior.

FIG. 2 shows the torch angle in the welding of this embodiment, and FIGS. 2 (a) and 2 (b) show the case of fillet welding in a horizontal position.
FIG. 2 (c) shows the case of downward welding.

As is clear from the results shown in Table 3, the present invention has a welding speed of 15
At a high speed of 0 cm / min, the bead shape and appearance were good, and the arc stability was also good. On the other hand, the comparative example was inferior in bead appearance, shape, and arc stability.

Example 2 In order to investigate the influence of the wire diameter in the present invention, a wire having a wire diameter of 1.2 mm to 3.2 mm was used under the welding conditions shown in Table 4,
This example was carried out by changing the welding speed. Implementation results first
Shown in the figure. Fig. 1 shows fillet welding in a horizontal position.
It is a graph which shows a wire diameter, welding speed, welding workability, and the relationship of the quality of a welding part. In Fig. 1, ○, △ indicates that the bead shape, appearance, and arc stability are good or slightly inferior, The case is even worse.

As is apparent from FIG. 1, when the wire diameter is 1.4 mm or more, good workability can be obtained even at a speed of 150 to 180 cm which is a practically sufficient speed in high speed gas shielded arc welding.

Example 3 In order to investigate the influence of the electrode distance in the present invention, FIG. 3 shows the results of carrying out welding by changing the electrode distance between 15 and 100 mm under the welding conditions in Table 5. FIG. 3 is a graph showing the relationship between the interelectrode distance and welding workability. Welding workability survey items include arc stability, spatter generation state (size, number), slag cover and peeling, bead appearance and shape, etc. Workability in tandem welding with a gap of 100 mm or more is evaluated as 5 did. Workability score is 4
In the case of ~ 5, the workability is good, and in the case of 3-4, it is slightly inferior. When welding was performed at a low speed (30 to 40 cm / min), the welding workability was good.

As is clear from FIG. 3, the welding workability tends to deteriorate as the distance between the electrodes is reduced from 100 mm, but it becomes good when the distance is less than 50 mm. Therefore, in the present invention, the distance between the electrodes is more preferably 50 mm or less.

Example 4 In order to investigate the influence of the inter-electrode distance in the present invention, welding was performed by changing the polarity under the welding conditions shown in Table 6. Seventh result
Show in vote. In the comprehensive evaluation of Table 7, Shows particularly good, good, and slightly inferior, respectively. Also, the bead appearance / shape and workability are ranked on a scale of 5 points.

As can be seen from Table 7, particularly good workability is exhibited when the polarity is the same in the leading and trailing lines.

Example 5 The influence of the wire diameter in the present invention was investigated by downward welding. Table 8 shows the welding conditions, and Fig. 4 shows the welding results. Fourth
The figure is a graph showing the relationship between the wire diameter, the welding speed, the welding workability, and the quality of the welded portion in downward welding. In FIG. Respectively, if the bead shape, appearance, and arc stability are good or slightly inferior, The case is even worse. No welding defect was observed in any case.

As is apparent from FIG. 4, when the wire diameter is 1.4 mm or more, good results were obtained even when the welding speed exceeded 400 cm / min.

FIG. 5 (a) is a groove shape of welding in the present embodiment,
FIG. 6B is a cross-sectional view showing the welding stacking method in this embodiment.

[Effects of the Invention] As described above, according to the present invention, the bead shape, appearance,
A high-speed arc welding method was obtained with good arc stability and no welding defects.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between wire diameter, welding speed and weldability in one embodiment of the present invention, and FIGS. 2 (a) to 2 (c).
Is a schematic view showing a torch angle in each embodiment of the present invention,
FIG. 3 is a graph showing the relationship between the electrode distance and welding workability in another embodiment of the present invention, and FIG. 4 is the relationship between the wire diameter, welding speed and weldability in yet another embodiment of the present invention. 5 (a) and 5 (b) are cross-sectional views showing a groove shape of welding and a stacking method in still another embodiment of the present invention.

Claims (4)

[Claims] 1. In a multi-electrode gas shield welding method, a metal flux-cored wire is used for the preceding first electrode,
A high-speed gas shield arc welding method characterized in that a titania-based flux-cored wire is used for at least the final electrode of the following electrodes. 2. The metal-based flux-cored wire and the titania-based flux-cored wire have a diameter of 1.4 mm.
The high-speed gas shielded arc welding method according to claim 1, which is the above. 3. The high-speed gas shielded arc welding method according to claim 1 or 2, wherein the polarities of the preceding two electrodes are the same. 4. The high-speed gas shield arc welding method according to claim 1, 2, or 3, wherein the distance between the electrodes is 50 mm or less.