JP2546955B2 - 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 aluminum alloy.

[0002]

2. Description of the Prior Art In MIG welding of aluminum or aluminum alloy, 5 to 10 kg usually wound on a spool is used.
The MIG welding wire is sent out by a push type feeding roller, passed through a conduit tube that is flexibly arranged, and the wire is fed by a current-carrying tip inside a welding torch arranged at the tip of the wire.

An arc is generated between the fed wire tip and the base material. The base material is melted and dug down by the arc force, and the wire forms droplets in the shield gas shielded from the atmosphere and moves to the base material side, and the molten pool solidifies to form a weld.

There are two main difficulties in aluminum MIG welding in obtaining a good weld.

That is, one is that aluminum has a large difference in hydrogen solubility between a liquid phase and a solid phase, and blow holes due to hydrogen are extremely likely to occur.

[0006] The other is that since the aluminum mig wire is soft, it is easily scraped by the feeding roller, and the shavings accumulate in the conduit tube, which hinders the constant speed feeding of the wire, resulting in stable welding. The part cannot be formed, resulting in defective fusion and defective shape.

Therefore, in manufacturing the wire, the surface is completely degreased in order to remove oils and fats and stains used for processing. Further, in welding work, strict control is required such as dehumidifying the work place and frequently cleaning the feeding route.

[0008]

However, by attaching a lubricating substance to the surface of the wire to reduce the shavings on the feed roller and to reduce the feed resistance in the feed path, a stable constant speed is achieved. When attempting to obtain the supply, there is a problem that the blowhole resistance is deteriorated due to hydrogen contained in the lubricating substance.

It is an object of the present invention to provide a MIG wire for aluminum welding which solves the above-mentioned problems of the prior art and enables stable constant speed feeding.

[0010]

In order to solve the above-mentioned problems, the present inventor tried to attach a lubricating substance having no hydrogen source to the wire surface, and as a result, among the lubricating substances, polyether was used. The fluorine derivative (1) is most suitable, and an aluminum mig wire having both good feedability and blowhole resistance can be obtained, which is the present invention.

That is, the MIG wire for aluminum welding according to the present invention is characterized in that the surface thereof has 0.2 g / m ² or more of a fluorine derivative of polyether which is liquid at room temperature.

The present invention will be described in more detail below.

[0013]

[Action]

As described above, the present inventor has conducted various studies on the lubricating substance having no hydrogen source, and the results will be described below.

First, MoS ₂ which is solid at room temperature and Japanese Patent Application No. 1-1
With a lubricating substance such as PTFE (polytetrafluoroethylene) proposed in 99627, when it is attached to the surface of the aluminum wire to such an extent that the feed resistance can be reduced, it peels itself during welding and the conduit It was not possible to obtain a constant speed feed for a long time by depositing inside. Also,
It has been found that adverse effects such as increase of fine spatter generated during welding, narrowing of cleaning width, and blackening of bead surface are adversely affected.

This phenomenon is because it is difficult for the solid lubricating substance to evenly cover the surface of the wire with a small amount, and the solid lubricating substance cannot satisfy all the various characteristics required for the welding wire.

Further, a liquid substance having no hydrogen source, for example, a straight-chain hydrocarbon in which hydrogen is replaced by fluorine,
It has been found that a polymer of ethylene trifluoride chloride proposed in Japanese Patent Application No. 44-90023, which is generally called a fluorine oil, lacks lubricity and has little effect of improving feedability. Increasing the adhesion amount to such an extent that the effect of improving the feedability is adversely affected such that the cleaning width at the time of welding becomes narrow and the bead surface becomes black.

This is a liquid PTFE polymer (
Formula 1) and polymers of trifluorochloroethylene (chemicals below
Formula (2) has no polar group, and therefore has poor adsorption ability on the metal surface, and is considered to have insufficient lubricity.

Embedded image

Embedded image

On the other hand, in the case of a fluorine derivative of polyether, the above-mentioned adverse effects do not occur and, moreover, the remarkable effect of improving the feedability is that the adhesion amount on the surface of the aluminum wire is 0.2 g / m ^2. Obtained from small quantities.

The fluorine derivative of polyether has the following chemical structure:
Perfluoropolyethers represented by formulas 3, 4, 5, and 6 are typical ones, and all have a C—O—C bond. It is considered that the reason why the polyether exhibits the effect of improving the feedability in a small amount is that this binding form improves the oiliness and the adsorption ability.

Embedded image F- (CF ₂ —CF ₂ —CF ₂ —O) n —CF ₂ —CF
₃

Embedded image

Embedded image CF ₃ -[(-O-CF-CF ₂ ) n- (O-CF ₂ ).
m] -OCF ₃

[Chemical 6]

The polyether fluorine derivative used in the present invention is not particularly limited as long as it is liquid at room temperature, but the desirable embodiments are shown below.

Among the fluorine derivatives of polyether, those having a relatively small kinematic viscosity are preferable, and 270 at 38 ° C. is preferable.
Those below cst are optimal. The kinematic viscosity of 400 cst is slightly less effective in improving the feeding resistance than that of 270 cst or less. This is probably because if the kinematic viscosity increases too much, the slipperiness with the conduit will rather deteriorate. On the other hand, if the kinematic viscosity is too small at 0.9 cst, the effect of improving the feed resistance will be small, probably because the film strength is weak.

The kinematic viscosity of the polyether increases as the average molecular weight increases, but the kinematic viscosity also differs depending on the structure. Further, the polyethers are compatible even if they have different average molecular weights and viscosities, and they can be mixed and adjusted to an optimum viscosity before use. From these aspects, the average molecular weight is 100
Fluorine derivatives of polyethers from 0 to 6250 are preferred. If the average molecular weight is less than 1000, the strength of the coating is weak and the effect of improving the feed resistance is small, and if it exceeds 6250, the sliding property with the conduit is deteriorated.

Of course, from the fluorine derivatives of polyether having an average molecular weight of 1000 to 6250, the optimum one having a kinematic viscosity of about 1 to 270 cst at 38 ° C. can be selected.

The amount of the fluorine derivative of polyether adhering to the wire surface is confirmed as follows.

First, a predetermined amount (3-5 g is sufficient) of an aluminum wire to which a fluorine derivative of polyether is attached is sampled,
Dissolve and extract in a solvent. At this time, the solvent is Freon 113
And ultrasonically wash and extract. Instead of the CFC 113, another CFC solvent or organic solvent that easily evaporates and has a high solubility of the fluorine derivative of polyether may be used.

The extracted fluorine derivative of polyether is mixed with 0.2 g of KBr. At this time, if the liquid amount is too large, the solvent is evaporated to a proper amount and mixed with KBr. KBr impregnated with a fluorine derivative of polyether is dried at 110 ° C. for 1 min and molded, and then Fourier transform infrared analysis is performed by a transmission method.

Using a separately prepared standard sample, a calibration curve for the absorbance at a wavelength (about 1240 cm ^-1 ) showing a strong absorption based on the weight of the fluorine derivative of polyether and the stretching vibration of the C--F bond was obtained, and From the calibration curve, know the weight (μg) of the fluorine derivative of polyether attached to the wire.

Next, the weight of the fluorine derivative of polyether obtained here is divided by the weight (g) of the sampled wire, and the adhered amount of the fluorine derivative of polyether per unit weight.
Calculate (μg / g wire 1). Convert from the nominal diameter of the aluminum wire to the adhesion amount per wire surface area m ² . here,
The surface of the wire is assumed to be perfectly smooth and round, and the specific gravity of the aluminum wire is 2.70.

Next, examples of the present invention will be described.

[0031]

Embodiment 1

Aluminum wire A5183WY (1.6 mm
Various lubricating oils shown in Table 1 were adhered to the surface of φ).
Lubricating oils are five kinds of perfluoropolyether, mineral oil type lubricating oil, animal and vegetable oils and fats, PTFE, and trifluorochloroethylene.

First, an aluminum wire was processed to a diameter of 1.6 mm, degreased in an organic solvent, and then perfluoropolyether was attached. The method is a method of diluting perfluoropolyether in a volatile Freon solvent and dipping the wire in the solution. Further, the control of the adhered amount was performed by adjusting the concentration of perfluoropolyether. Perfluoropolyether has an average molecular weight of 1500, 38
A kinematic viscosity at c of 18 cst was used.

The mineral oil-based lubricating oil shown in the comparative example had a kinematic viscosity of 94 cst at 40 ° C., and was attached by the same method as in the case of perfluoropolyether, using trichloroethane as the solvent.

The trifluoroethylene chloride shown in the conventional example has an average molecular weight of 700 and a kinematic viscosity at 25 ° C. of 20 to 50 cs.
The product of t (trade name: Daifloyl # 3) was diluted in a volatile CFC solvent, and the adhesion method was the same as in the case of perfluoropolyether. Conventional examples A-7 and A-8
Is a technique according to Japanese Patent Application No. 44-90023.

Further, the conventional examples A-5 and A-6 are disclosed in Japanese Patent Application No.
This is a technique for attaching PTFE as disclosed in Japanese Patent Application No. 3-121831 and Japanese Patent Application No. 1-199627. The adhesion of PTFE was also carried out by the same method as in the case of perfluoropolyether.

Further, in the comparative examples shown in A-2, A-3, and A-4, mineral oil and animal and vegetable oil generally used in steel welding wires are adhered to aluminum wires to improve perfluoropolyether and feedability. This is a comparison of the effects.

Table 1 shows the results of examining the deposition state in the conduit, the feedability, and the B.H resistance of aluminum wires to which various types of lubricating oils have been attached. In the welding test, the conduit was formed into a loop of 380 mmφ within 3 m, and was given a further twist to weld under fairly severe conditions.

[0039] It should be noted that the deposition condition in the conduit is about 2
After continuous MIG welding at 60 A for 5 minutes, the inside of the conduit was washed with acetone, and the amounts of aluminum powder and dirt collected in the acetone were visually compared. ◎: no deposit, ○: almost no deposit, △: little deposit, △: large deposit
Was evaluated.

The feedability was compared by measuring the fluctuations in current, voltage and feed resistance during continuous MIG welding at approximately 260 A for 5 minutes. When the feedability was excellent, it was evaluated as ⊚, when it was good, it was evaluated as ◯, when it was slightly inferior, it was evaluated as Δ, and when it was inferior, it was evaluated as x.

B.H resistance is 8 mm in thickness, 4 mm in gap,
The groove with a backing metal was welded sideways at a groove angle of 60 °, and two-layer three-pass welding was performed, and an X-ray transmission test was performed to make a determination. The criterion is JI
According to SZ 3105.

As is clear from Table 1, the use of perfluoropolyether shows a remarkable effect of improving the feedability even from a very small amount of 0.2 g / m ² . The deposition amount was increased stepwise to about 8 g / m ² , but there was a tendency that the feedability was improved as the deposition amount was increased. BH resistance was also good.

On the other hand, in Comparative Examples A-2, A-3, and A-4, since mineral oil and animal / vegetable oil have a hydrogen source, the B.H resistance is deteriorated, so that they are positively attached to the aluminum wire. Things should be avoided. Further, in the conventional example using PTFE or ethylene trifluoride chloride, the effect of improving the feedability cannot be expected.

[0044]

[Table 1]

[0045]

Example 2

Aluminum wire A5356WY (1.6 mm
To the surface of φ), perfluoropolyethers having different kinematic viscosities shown in Table 2 were attached in the same manner as in Example 1,
The state of deposition in the conduit, feedability, and BH resistance were investigated. The evaluation method of each characteristic is the same as that of the first embodiment. The results are shown in Table 2.

It can be seen that in all cases, the feedability is remarkably improved as compared with the conventional wire. Among them, the optimum kinematic viscosity is about 1 to 270 cst.

[0048]

[Table 2]

1 to 5 show current / voltage / feed in welding test of A-11 wire and B-4 wire of the present invention example and each wire of A-6, A-7 and B-1 of conventional example. A resistance variation record is shown. In the example wires A-11 and B-4 of the present invention, 5
We were able to weld stably for a minute, but with the conventional wire, the feed resistance increased significantly with the passage of time, and the fluctuation of the current was also large.
We were unable to continue satisfactory welding.

In the above examples, the method of adhering the perfluoropolyether was shown by immersing it in a dilute solution. However, the method is not limited to this, and the perfluoropolyether or its diluting solution may be extended. Wires may be used, or a medium such as felt may be impregnated with perfluoropolyether or its diluting solution and the wire may be contacted with it, or perfluoropolyether or its diluting solution may be sprayed in the atmosphere. Good results can also be obtained by passing a wire through the wire.

At this time, a kinematic viscosity that is easy to handle may be selected depending on the coating method. For example, when impregnating felt or the like, one having a relatively low kinematic viscosity would be preferable, and when used for wire drawing, one having a large kinematic viscosity would be suitable from the viewpoint of wire drawability.

[0052]

As described in detail above, according to the present invention,
It is possible to provide an aluminum mig wire having good feedability without deteriorating BH resistance. Therefore, the construction management is facilitated and the stability of the quality of the welded joint is improved.

[Brief description of drawings]

FIG. 1 is a view showing a variation record of current / voltage / feed resistance in a welding test of Inventive Example wire A-11.

FIG. 2 shows currents in a welding test of a conventional wire A-6.
It is a figure which shows the fluctuation | variation record of voltage / feed resistance.

FIG. 3 shows currents in a welding test of a conventional wire A-7.
It is a figure which shows the fluctuation | variation record of voltage / feed resistance.

FIG. 4 is a diagram showing a variation record of current, voltage, and feed resistance in a welding test of Inventive Example Wire B-4.

FIG. 5: Current in welding test of Conventional example wire B-1
It is a figure which shows the fluctuation | variation record of voltage / feed resistance.

Front Page Continuation (72) Inventor Tomoyuki Tachibana 100-1 shares Urakawachi, Miyamae, Fujisawa-shi, Kanagawa Formula Company Kobe Steel Works, Fujisawa Plant (72) Inventor Ryo Ogawa 100-1 shares Urakawachi, Fujisawa, Kanagawa Ceremony Company Kobe Steel Fujisawa Office

Claims (1)

(57) [Claims] 1. A MIG wire for welding aluminum, which has a fluorine derivative of polyether which is liquid at room temperature of 0.2 g / m ² or more on its surface.