JP2723785B2 - MIG wire for aluminum welding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a consumable electrode wire used for MIG welding aluminum or an aluminum alloy.

[0002]

2. Description of the Related Art In MIG welding of aluminum or aluminum alloy, a wire for 5 to 10 kg of MIG welding wound on a spool is usually fed by a push type feed roller, and is flexibly arranged. Then, the wire is passed through a conduit tube, and the wire is contact-fed with a current-carrying tip in a welding torch disposed at the tip.

An arc is generated between the tip of the supplied wire and the base material. The base metal is melted and dug down by the arc force, and the wire becomes a droplet in the shielding gas shielded from the atmosphere and moves to the base material side, and the molten pool is solidified to form a weld.

One of the major problems with MIG welding of aluminum in obtaining a good weld is uniform feedability of the welding wire.

[0005] That is, when the wire passing speed (feeding speed) when passing through the conduit tube and passing through the current-carrying tip becomes unstable, the welding current and the preset welding current are set so that a good weld is obtained. The relationship between the arc voltages cannot be maintained. Such a failure phenomenon is generally called arc instability. As a result, a stable weld cannot be formed, resulting in poor fusion and poor shape.

[0006] Such a phenomenon is caused by a conduit tube.
When the (feeding path) is long, when the conduit is strongly bent in the vicinity of the welding torch, or when welding is continuously performed for a long time, the problem occurs remarkably. One of the causes of such arc instability is that the aluminum welding wire is softer than, for example, steel wire, so that it is easily shaved by the feed roller, and aluminum fine powder accumulates in the conduit tube, and the wire is not fixed. Rapid delivery may be hindered.

[0007] For this reason, conventionally, in producing a wire, a device has been devised to minimize surface flaws and to improve feedability. On the other hand, in welding work, strict control is required, such as frequent cleaning of the feed route.

[0008] However, even with such ingenuity and management, the conventional aluminum MIG welding wire has not yet reached a fundamental solution.

The present invention has been made in view of the above circumstances, and has as its object to provide an aluminum welding mig wire capable of obtaining a stable arc even in continuous welding for a long time or in a state where a conduit is tightly bent. Things.

[0010]

The inventor of the present invention has made intensive studies to solve the above-mentioned problems, and as a result, has increased the smoothness of the wire surface to a level which cannot be obtained by ordinary drawing. It has been confirmed that it is difficult to remove the steel by the method described above, and furthermore, experimental studies have been repeated on concrete measures for that, and the present invention has been made here.

That is, according to the present invention, when the apparent surface area of the measurement portion where the actual surface area of the wire surface is measured is Sm (mm ² ) and the actual surface area of the wire surface of the measurement portion is Sa (mm ² ),
A gig wire for aluminum welding characterized in that a wire specific surface area represented by {(Sa / Sm) -1} × 1000 is 0.50 or less.

[0012]

The present invention will be described below in more detail.

As described above, according to the present invention, the smoothness of the wire surface of the MIG wire for aluminum welding is adjusted to an extremely high level. Thus, such unprecedented smoothness can be obtained by various methods. . For example, using a single crystal diamond die for the wire drawing die, increasing the number of wire drawing as much as possible after the peeling step, and using a lubricating oil used for wire drawing below the viscosity normally used, for example, 150 cs
It can be obtained by combining t (38 ° C.) or less.

Further, as a result of studying another industrially easy means, it has been found that it is effective to mix a fine abrasive in a lubricant.

A general manufacturing process of the MIG wire for aluminum welding of the present invention is as follows. Of course, it is needless to say that the present invention is not limited to this manufacturing process.

After rolling the aluminum billet adjusted to a predetermined component, annealing and drawing are repeated as appropriate to reduce the wire diameter. During or after the wire drawing process after the final annealing, the surface layer that adversely affects the quality of the weld such as the alumina-forming layer on the wire surface is removed by shaving off the surface layer thinly. Thereafter, the wire is further drawn as required to obtain a predetermined product diameter, washed in an organic solvent to remove lubricating oil and dirt attached to the surface of the wire, and wound around a spool.

In the wire drawing process, the lubricating oil is strictly controlled in order to suppress the generation of scratches on the wire surface and extend the life of a die used for wire drawing. Is used as much as possible.

Mixing the abrasive with the lubricating oil is to mix so-called solid foreign matter into the lubricating oil whose cleanliness is to be strictly controlled, and is a new idea that cannot be created from conventional ideas. .

The material of the abrasive used is not particularly limited. For example, black silicon carbide, green silicon carbide, white alumina,
Commercially available polishing fine particles such as brown alumina, zirconium oxide, and cerium oxide may be used.
Many commercially available abrasives are obtained by mixing these components.

What is important is the particle size of the abrasive. It is necessary that the particle size is configured so that the maximum particle size does not exceed 50 μm, and the most suitable one is one having a particle size of about 30 μm or less and 10 μm or less of about 70%.

The abrasive may be used by mixing 5 to 30 vol% of the above-mentioned abrasive in a commonly used lubricating oil. In this range, the effect of smoothing the surface is obtained and the drawability is poor. Not inhibited.

The next important points are the position and the number of times of drawing with lubricating oil containing an abrasive, and the drawing is performed after peeling. A sufficient effect can be obtained when the number of times of drawing is one, and the improvement effect is increased little by little as the number of times is increased twice or three times.

The MIG wire for aluminum welding of the present invention is obtained by the above-described manufacturing process, and the surface of the wire has a specific surface area defined as follows.

That is, assuming that the apparent area of the measurement portion where the actual surface area of the wire surface is measured is Sm (mm ² ) and the actual surface area of the wire surface of the measurement portion is Sa (mm ² ), {(Sa / S
m) -1} × 1000 and a wire specific surface area of 0.50
It is as follows. Here, the apparent area of the measurement part (Sm)
Is an area represented by length x width when the measurement portion is developed on a plane. In the present invention, the actual surface area of the 500 μm × 600 μm (= 300,000 μm ² ) portion was measured after the measurement portion was developed on a plane. The wire specific surface area can be measured by an image processing method.

If the wire specific surface area exceeds 0.50, the amount of aluminum differential generated in the feed roller accumulates in the conduit, and a stable arc cannot be obtained for a long time. More preferably, it is 0.30 or less.

Next, examples of the present invention will be described.

【Example】

First, an aluminum alloy wire (type 51)
83), and after drawing three times, the product diameter was 1.
In the process of manufacturing 6 mmφ, the number of times of drawing using lubricating oil mixed with an abrasive was changed once, twice, and three times, and finished to a predetermined product diameter. Further, the number of times of wire drawing after peeling was increased to 4 to 6 times, the viscosity of the lubricating oil was lowered, and a part of the lubricated oil was drawn with a natural diamond die.

As a wire sample for measuring the wire specific surface area, from a product wire wound on a spool, a sample of about 20 mm was taken from any three places so as not to scratch as much as possible, and petroleum ether and acetone which did not corrode the metal surface were used. ,
Ultrasonic cleaning in an organic solvent such as carbon tetrachloride or chlorofluorocarbon, or with a liquid (hot water or other degreasing liquid) that seems to be the most suitable to remove the lubricant depending on the type of lubricant used in the processing process As a result, impurities such as dirt and oils and fats attached to the wire surface were removed. The ultrasonic cleaning was performed one by one so that the wires did not rub against each other to cause a flaw.

The specific surface area of the wire was measured using an electron beam three-dimensional roughness analyzer (ERA-800, manufactured by Elionix Inc.).
0), and from the image processing method equipped in this,
The apparent area Sm (mm ² ) of the measurement part where the actual surface area of the wire surface was measured, and the actual surface area Sa of the wire surface of the measurement part
(mm ² ) was measured, and the wire specific surface area represented by {(Sa / Sm) -1} × 1000 was calculated and defined as the smoothness.

The wire specific surface area was measured at three locations shifted by about 120 degrees from an arbitrary cross section (periphery) of one sample, and the simple average of the measured values of a total of nine locations of the three samples was defined as the wire specific surface area. . Also, in the actual production of wires, it is noted that flaws received from dies by wire drawing, nicks and abrasions caused by contact between facilities and wires, etc. are as little as possible, so the same situation as the actual situation In the sense, the smoothness was measured by selecting a portion having no flaw.

Also, a feeding system in which a conduit is bent extremely.
(A 270mmφ loop was made in the middle of a 3m conduit, and it was bent to a radius of curvature of 100mm just above the torch.)
The aluminum alloy powder deposited in the conduit welded for one minute was collected on a filter paper while flowing with a solvent (acetone), and quantitative analysis was performed as pure aluminum to compare the amount of aluminum powder generated, and the welding current and arc voltage during welding. Were recorded and the arc stability was compared.

Table 1 shows the specific surface area, the amount of deposited aluminum powder, and the arc stability of a wire drawn with lubricating oil mixed with an abrasive after peeling.

With respect to the specific surface area of the wire, the wire of the conventional example is about 0.80, whereas the wire of the present invention has a wire specific surface area of No. 2 which is drawn once with lubricating oil mixed with an abrasive. No. 3 which has been greatly improved to .17
It can be seen that the wire No. 4 drawn ten or three times is gradually improved to 0.08. Moreover, the number of wire drawing after peeling is 4-6.
It can be seen that the wire specific surface area is improved to 0.50 or less also in the case where the viscosity of the lubricating oil is decreased as the number of times increases.

The amount of aluminum powder generated in a feed system in which a conduit is extremely bent to a level that is not normally used is 2.5 mg in the conventional wire, whereas it is 2.5 mg in the present invention. Of the wire, the wire was sharply reduced to 1.0 mg for No. 2 drawn once, 0.7 mg for No. 3 drawn twice and 0.5 mg for No. 4 drawn three times.

The relationship between the amount of generated aluminum powder and the smoothness is as follows:
The wire of the present invention having a wire specific surface area of 0.3 or less is particularly good, and the deposition amount of aluminum powder is reduced to one third or less of the wire of the conventional example.

On the other hand, with respect to the stability of the arc welded at about 260 A and 30 V, the current and voltage began to be disturbed in about 3 minutes from the start of welding in the conventional wire, but in 5 minutes in the wire of the present invention. Welding was stable.

As can be seen from this example, the wire specific surface area (smoothness), the amount of aluminum powder generated, and the stable arc duration are well correlated.

The means for using the fine abrasive particles to improve the smoothness can be achieved by mixing with a solvent after mixing with the lubricating oil shown in the embodiment and then including the mixture in a felt or the like and pressing against the wire surface. Good results were obtained by polishing or polishing with a roll-shaped buff material in which an abrasive was dispersed and held in advance.

[0039]

[Table 1]

[0040]

As described above in detail, the use of the MIG wire for aluminum welding according to the present invention makes it possible to obtain a stable arc even in a state where continuous welding is performed for a long time or in a state where the conduit is tightly bent, so that the construction management is easy. And the stability of welded joint quality is improved.

Continuation of the front page (56) References JP-A-57-56170 (JP, A) JP-A-8-19893 (JP, A) JP-A-7-32187 (JP, A) JP-A-7-178586 (JP, A) JP-A-1-202391 (JP, A) JP-A-3-66495 (JP, A)

Claims (3)

(57) [Claims] When the apparent surface area of a measurement portion where the actual surface area of a wire surface is measured is Sm (mm ² ) and the actual surface area of the wire surface of the measurement portion is Sa (mm ² ), {(Sa / Sm ) -1} ×
A MIG wire for aluminum welding, wherein a specific surface area of a wire surface represented by 1000 (hereinafter, referred to as a wire specific surface area) is 0.50 or less. 2. The MIG wire for aluminum welding according to claim 1, wherein the wire specific surface area is 0.30 or less. 3. A wire drawing process in which wire drawing is performed at least once using a lubricant mixed with at least abrasive particles in the wire drawing process after the surface of the wire is stripped in the processing step. MIG wire for aluminum welding as described in.