JPH02268976A - Gas shielded arc welding method - Google Patents

Abstract

PURPOSE:To obtain a sound weld zone by feeding continuously two pieces or more of element wires having the same cross-sectional area, while twisting them, and melting and welding them by arc heat, at the time of consumable electrode type gas shielded arc welding or non-consumable electrode type gas shielded arc welding. CONSTITUTION:When a wire twisting machine 3 is rotated in the prescribed direction by seven pieces of supply spools 2, the center supply spool 2 becomes the center line and seven pieces of element wires 1 are twisted by a drawing die 4 and formed integrally. A twisted welding wire 5 is fed continuously to an MIG welding torch 7 by a feed roller 6. The wire is melted by an arc 9 generated by electric power supplied through an electric conduction chip from a welding power source 12 under a shielding gas atmosphere blown out of a shielding nozzle 8, and welded as a welding bead 10 on a material 11 to be welded. In such a way, the welding wire 5 is fed continuously to a torch tip part, while twisting the element wires 1, therefore, it can be melted and welded in a clean state.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable to consumable electrode type gas shielded arc welding (hereinafter referred to as MIG welding) and non-consumable electrode type gas shielded arc welding (hereinafter referred to as MIG welding) when using a stranded wire. This invention relates to a gas-shielded arc welding method commonly used in TIG welding.

[Conventional technology]

Conventional stranded wire is often used in MIG welding and IG welding for reasons such as stabilizing feedability, increasing welding speed, or ensuring a certain weld penetration depth.

In addition, the stranded wire has great utility in the production of welded structures, such as by twisting together a plurality of raw wires with different alloy compositions and arc welding them into a single piece to obtain a weld metal with the desired alloy composition.

However, as shown in the cross-sectional view in Figure 14, the sintered wire has grooves and gaps between the bare wires 1°1 on its outer periphery, so the area around the wire is contaminated with moisture, oil, fat, dust, etc. Objects 34 tend to clump together (the wire surface is much more contaminated than a normal circular cross-section wire).

This contaminant 34 is a mixture of moisture, oil, fat, etc.
Since it has entered the narrow gap between the bare wires 1, 1, it cannot be easily cleaned even by cleaning treatment with thinner, ether, etc., or pickling treatment with aqua regia, etc.

This unevenness due to contamination or surface oxidation on the wire surface is caused by
MTG welding and TIG welding have a significant negative effect on welding welding properties, and in MIG welding, it is often not possible to obtain a stable arc even when the welding conditions are set to the optimal values, resulting in uneven and meandering weld beads. or scale may occur on the bead surface. Also T.I.G.
In welding, serious drawbacks occur in welding work, such as the bead shape becoming convex and the bead surface not being glossy.

If overlay welding or butt welding of joints is performed under the above conditions, welding defects such as blowholes and poor fusion will occur. Currently, it cannot be used for important structures such as

[Problem to be solved by the invention]

The present invention was proposed in view of these circumstances, and
In MIG welding and TIG welding using glued wire, it is possible to produce sound welds without causing welding problems such as poor fusion, blowholes, arc instability, poor bead shape, and poor appearance. The object of the present invention is to provide a gas-shielded arc welding method that can be obtained.

[Means to solve the problem]

To this end, the present invention has the following advantages: (1) In consumable electrode type gas shielded arc welding or non-consumable electrode type gas shielded arc welding, two or more bare wires with the same cross-sectional area are continuously fed while being fitted together, and are melted by arc heat. Welding (2)
) Item 1 is characterized in that a plurality of raw wires having different alloy components are continuously fed while being twisted together, and melted and welded.

[Effect]

According to the method of the present invention, two or more raw wires are joined together to form a single wire, and are continuously fed to the tip of a MIG welding torch or TIG welding torch, and the workpiece is welded with arc heat. By melting and welding, a sound welded part can be obtained.

〔Example〕

An embodiment of the gas-shielded arc welding method of the present invention will be explained with reference to the drawings. Figure 1 is a schematic diagram showing an embodiment of the first embodiment in which the method of the present invention is applied to MIG welding, and Figure 2 is a cross-section of the wire in the same manner. Figure 3 is a voltage and current waveform diagram when igniting a small current arc of the wire in the specific example according to the above, and Figure 4 is an explanatory diagram of welding conditions in the specific example above.
FIG. 5 is an external view of the weld bead, FIG. 6 is a sectional view of a wire in another specific example, and FIGS. 7 and 8 are explanatory diagrams of welding conditions and weld metal in the same. Fig. 9 is a schematic diagram showing a second embodiment in which the method of the present invention is applied to TIG welding, Fig. 10 is an explanatory diagram of welding conditions in the specific example according to the above, and Fig. 1) shows the weld bead. External view, 1st
FIG. 2 is an explanatory diagram of wetting of the weld bead same as above, and FIG. 13 is an explanatory diagram of wetting index same as above.

First, with reference to FIG. 1, a first embodiment in which the gas shielded arc welding method of the present invention is applied to MIG welding will be described.

In FIG. 1, reference numeral 2 indicates seven supply spools, and when the overhang line machine 3 rotates in a certain direction, the central supply spool 2
is the center line, and the seven bare wires 1 are fitted together with a squeeze die 4 and integrated. The fitted welding wires 5 are continuously fed to the MIGVg contact torch 7 by a feed roller 6, and under a shield gas atmosphere spouted from a shield nozzle 8, electricity is generated by the electric power supplied from the welding power source 12 through the current-carrying tip. It is melted by an arc 9 and welded as a weld bead 10 onto the material to be welded 1). At this time, the welding wire 5 is continuously fed to the tip of the torch while loosening the bare wire 1, so the welding wire 5
The material to be welded 1) can be fused and welded in a clean state without moisture, dust, or oils and fats accumulating in the grooves or gaps on the outer periphery, and as a result, a sound weld bead 10 can be obtained.

In this case, the bare wires 1 having a circular cross-sectional shape and the same cross-sectional area are used, and the number of raw wires 1 to be sewn together is 2, 3, 4, and 7 grains. It is desirable that the cross-sectional shape of each wire be as shown in FIG. 2 Δ to D. The reason for excluding 5th wood cutting and 6th wood cutting is that 1.
This is because the wire is deformed, causing feeding failure. Furthermore, the reason why the maximum number of warp wires is set to seven is that if the number of bare wires exceeds seven, the device will become bulky. Furthermore, regarding the alloy composition of the raw wire 1, not only can the raw wire 1 be made of the same alloy composition, but also raw wires 1 having different alloy compositions may be twisted and integrated to adjust the alloy composition of the weld metal. It's easy to do.

A specific example of this first embodiment will be explained below.

Specific example I In MTG welding of stainless steel and high nickel alloys, importance is placed on the stability of the welding arc, sputtering, and the shape of the weld bead, and these welding workability are determined by the surface condition of the welding wire, that is, the oxidation on the wire surface. This is caused by the formation of a film or dirt that cannot be cleaned. Therefore, as an experiment to determine the quality of the wire surface, we used stainless steel wire (0.4φ Stainless steel wire (0.4φ x 7
The quality of the wire surface, that is, the weldability of both wires, was examined based on the arc phenomenon when a small current arc was applied to each 150-meter length of each sample.

Figure 3A shows the voltage and current waveforms of the wire sampled according to the present invention when the arc is ignited at a small current (approximately 60 A), and shows a good pattern in which the arc burns out continuously. No abnormalities were observed.

FIG. 3B shows the voltage and current waveforms of a commercially available wire. The waveforms fluctuate significantly up and down, and the arc burns up discontinuously. This is thought to indicate an abnormality in the wire surface condition, that is, an oxide film or slag formed on the surface of the droplet, which increases the surface tension of the droplet and causes the arc to flare up discontinuously. Using a high-speed camera, we observed the arcing phenomenon of a wire in which the voltage and current waveforms are significantly disturbed, and found that the droplets grew larger than those of the sampling wire of the present invention, and tended to flare up while vibrating like a sparkler. .

Furthermore, 5US304 was obtained using the MIG welding method according to the present invention and the conventional method using the wire described above! Bead with short circuit arc on iI plate
On-plate welding was performed and welding workability was compared and studied. An overview of the welding conditions and workability at that time is as shown in FIG.

In this experiment, as shown in FIG. 5A, the weld bead obtained by the method of the present invention had some spatter adhesion due to the short arc, but no abnormality was observed in the bead shape.

In addition, the arc transition is stable, and the number of short circuits at that time is 80.
The droplets were moving at a stable frequency of ~90 times/sec. As shown in FIG. 5B, the weld bead in the conventional method had a large amount of large grains of subafter attached, and the bead shape was significantly convex. Further, arc transfer was also unstable, and the number of short circuits at that time was very small, 20 to 50 times/second, and there was unstable droplet transfer.

Specific Example ■ The MIG method of the present invention was carried out in the following manner for welding aluminum bronze used as a corrosion-resistant and wear-resistant welding material for seawater pumps, sliding plates, etc.

Aluminum bronze is a corrosion-resistant and wear-resistant copper alloy made by adding AI in the range of 4 to 15% to a Cu base.
If a large amount of I is contained, the material will have even better wear resistance, but if 10% or more of AI is added, the forgeability will deteriorate significantly and the material will not be able to be used as a welding wire, so the specified chemical composition cannot be obtained. It is conceivable to combine drawable steel cable wire and bare aluminum wire and use them as a welding wire, but copper alloy wires do not oxidize on the wire surface, so if they are glued together and integrated, they will deteriorate over time. The disadvantage was that it could not be used as a welding material due to significant discoloration.

Therefore, as shown in Fig. 6, a bare aluminum wire 13 with a diameter of 0.53 mm is provided at the center, and six steel cable wires 14 with a diameter of 0.53 mm are strung together around its outer circumference to form a single wire. Overlay welding was performed using the MIG welding method of the present invention using a 1.6φn wire, and compared with the conventional Mrcm welding method using an aluminum bronze solid wire with a diameter of 1.6φ. An overview of the welding conditions and workability at that time is shown in FIG. 7, and FIG. 8 shows the chemical composition and hardness of weld metals obtained by the conventional method and the welding method of the present invention.

In this experiment, in the conventional method, the welding arc was unstable and scale on the bead surface often occurred, resulting in poor compatibility of the weld metal and poor fusion in the overlay weld. Furthermore, the AI content of the weld metal was 8.9%, which is at a high level for a solid wire, but was much lower than the 13.6% obtained by the welding method of the present invention. In the present invention, welding workability was also good, and a sound build-up weld of an aluminum-bronze-based copper alloy with a high Al content was obtained. Furthermore, Vickers hardness (v347) was unparalleled for copper alloys.

Next, referring to FIG. 9, a second embodiment in which the gas shielded arc welding method of the present invention is applied to TIG welding will be described.

In FIG. 9, when the overhanging wire machine 3 rotates in a certain direction, the central supply spool 2 becomes the center line, and seven bare wires 2
1 are glued together with the squeeze die 4 and integrated. The welded welding wire 25 is continuously fed to the wire guide nozzle 26 by the feeding roller 6, and the tungsten electrode 28 is connected to the welding power source 32 under a shielding gas atmosphere spouted from the shield nozzle 27' of the TTG welding torch 27. The electric power received by the welding material is melted by the generated arc 29 and deposited as a weld bead 30 on the workpiece 31 to be welded.

A specific example of this second embodiment will be explained below.

Specific example■ Regarding workability when welding Inconel 82 onto a carbon steel plate, we compared the present T■G welding method and the conventional sintered wire TI.
A comparison was made with the G welding method. Seven pieces of Inconel 82 bare wire with a diameter of 0.53 Tsuru are tied together to make a wire with a diameter of 1.6
A bead-on-plate weld was performed on a carbon steel plate, and compared with the conventional method. An outline of the welding conditions and workability at that time is shown in FIG.

In this experiment, the weld bead obtained by the method of the present invention was a good weld bead with a uniform bead waveform, as shown in FIG. 1) A.

In addition, the wire melted continuously and smoothly directly under the arc, and no abnormalities were observed. 1) As shown in Figure B, the weld bead produced by the conventional wire TIG welding method has a markedly uneven bead toe, lacks uniformity over the entire bead, and abnormalities in the wire melting state. The detachment and welding of droplets from the wire end progressed irregularly. This irregular welding is due to an increase in the surface tension of the droplet due to an oxide film or dirt on the wire surface.

The shape of a stable TIG weld bead as in the present invention is such that the wire melts directly under the arc and is drawn to the rear of the molten pool by the phenomenon of "wetness" of molten metal, forming a weld bead. As mentioned above, wires with irregularities on the wire surface, that is, wires with dirt that forms an oxide film or slag on the surface, grow large at the wire end due to the increase in the surface tension of the droplets.
This prevents migration due to the "wetting" phenomenon.

Note that a state where the molten metal has good wettability and is well adapted to the welded material is the weld metal 3 as shown in Figure 12.
It can be said that the smaller the contact angle (θ) of No. 3 and the smaller the value obtained by dividing the bead height (a) by the bead width (b), the better the "wettability". Therefore, in order to express "1 wettability", bead height (a), bead rll (b), or contact angle (θ) were measured and expressed as a wettability index using equation (1).

Wetting index = a / b Xθ',, ill first
Figure 3 shows the weld bead in Figure 1) A obtained by the present invention and the weld bead in Figure 1) B obtained by the conventional method, cut from a predetermined position, and the wetting index calculated from the cross-sectional shape of the bead. In the welding method of the present invention, the wetting index is as small as 6.7, and it can be said that the formation of an oxide film or slag that can prevent "wetting" is extremely small compared to the conventional method. In the conventional welding method, in which irregularities in the molten state were observed, the wetting index was approximately three times larger than that of the present invention, and the "wetting property" was significantly poor, resulting in a convex bead shape.

〔Effect of the invention〕

In short, according to the present invention, (1) in consumable electrode type gas shielded arc welding or non-consumable electrode type gas shielded arc welding, two or more bare wires with the same cross-sectional area are continuously fed while being glued together, and arc heat is used to Melting and welding;
(2) In step 1, by continuously feeding a plurality of raw wires with different alloy components while twisting them together and melting and welding them,
In MIG welding and TIG welding, which use stranded wire, a sound weld can be achieved without causing welding defects such as poor fusion or blowholes, arc instability, poor bead shape, or poor appearance. The present invention is industrially extremely useful because it provides a gas-shielded arc welding method that can achieve the following.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing an embodiment of the first embodiment in which the gas shielded arc welding method of the present invention is applied to MIG welding;
The figure is a cross-sectional view of the wire in the same example as above, and FIG. 3 is the voltage at the time of ignition of a small current arc of the wire in the specific example according to the above. Current waveform diagram, Figure 4 is an explanatory diagram of welding conditions in the same example as above, Figure 5 is an external view of the weld bead, Figure 6 is a cross-sectional view of the wire in another example, Figures 7 and 8. The figure is an explanatory diagram of welding conditions and weld metal in the same as above. Fig. 9 is a schematic diagram showing a second embodiment in which the method of the present invention is applied to TIG welding, Fig. 10 is an explanatory diagram of welding conditions in the specific example according to the above, and Fig. 1) shows the weld bead. External view, Figure 12 is an explanatory diagram of wetting of the weld bead as above, Figure 13
The figure is an explanatory diagram of the wettability index same as above. FIG. 14 is a sectional view of a conventional sintered wire. 1... Bare wire, 2... Supply spool, 3...
Sliding wire machine, 4... Squeezing die, 5... Welding wire, 6... Feeding roller, 7... MIG welding torch,
8... Shield nozzle, 9... Arc, 10...
Welding bead, 1)... Material to be welded, 12... Welding power source, 13... Aluminum bare wire, 14... fI bare wire, 21... Bare wire, 25... Welding wire, 26・
... Wire guide nozzle, 27 ... TIG welding torch, 27' ... Shield nozzle, 28 ... Tungsten electrode, 29 ... Arc, 30 ... Welding bead, 3
1... Material to be welded, 32... Welding power source, 33... Weld metal, 34... Contaminants. Agent Patent Attorney Masa Tsukamoto Figure 3 Figure 3 (A) Figure 4 Figure Figure Figure Figure Figure Figure

Claims (2)

[Claims] (1) In consumable electrode type gas shielded arc welding or non-consumable electrode type gas shielded arc welding, two or more bare wires with the same cross-sectional area are continuously fed while being twisted together and melted and welded by arc heat. Gas shielded arc welding method. (2) The gas-shielded arc welding method according to claim (1), characterized in that a plurality of raw wires having different alloy components are continuously fed while being twisted together, and melted and welded.