JPH03124391A - Copper plated steel wire for gas shielded arc welding - Google Patents

Abstract

PURPOSE:To eliminate the trouble, such as interruption, during continuous welding and to obtain a good-quality weld zone free from bead meandering, etc., by specifying the amt. of Ca interposed between a wire base and a plating layer and the oil deposition on the surface. CONSTITUTION:The amt. of the Ca interposed between the copper plating and iron base of the copper plated steel wire for gas shielded arc welding of <=1.6mm diameter to be mounted into pail pack is so determined as to satisfy the range of equation including the plating thickness of the Cu. More preferably, the tensile strength of the wire is determined to satisfy the range of 70 to 100kgf/mm<2> if the wire diameter is 1.6mm, 75 to 115kgf/mm<2> if 1.4mm, and 80 to 130kgf/mm<2> if 1.2mm. A bipolar electrolytic degreasing method, etc., prior to plating are effective to regulate the amt. of the Ca to be interposed between the surface plating layer of the wire and the steel base.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a wire for gas metal arc welding using a shielding gas containing CO2 and Ar as main components. In detail, the copper-plated steel wire (hereinafter referred to as wire) loaded in a bailback, which is mainly used for automatic arc welding using robots, etc., can be used for long periods of welding without problems such as interruptions. The present invention relates to a wire that can be welded with high quality and free from bead meandering.

(Prior Art) Recently, from the viewpoint of efficiency and quality, robot welding or automatic welding equipment that can operate ten or more torches at the same time is being adopted. As for the wire used in this case, instead of the conventional spool-wound wire weighing less than 20 kg, a wire housed in a so-called cylindrical bale bag that can accommodate 200 to 400 strands is increasingly being used. The characteristics required of the wire loaded in such a bailback are: (1) Since welding is performed continuously for tens of hours, the wire feeding performance can be maintained for a long time without interruptions due to chip clogging, etc. It is stable, and (2) because people do not work while looking at the arc, there is little wobbling at the tip of the wire and the weld bead does not meander.

However, the characteristics required of the wire loaded into these bailbacks cannot be fully satisfied with the characteristics of conventional spool-wound wire.
Currently, welding interruption problems are dealt with by increasing the frequency of tip replacement, and bead meandering is dealt with by using a wire straightener.

(Problems to be Solved by the Invention) The present inventors attempted to solve the above-mentioned problems with the wire loaded in the bail bag. We investigated whether there is a difference. As a result, as stated in Japanese Patent Application Laid-Open No. 58-35068, the wire loaded in the bailback has good straightness, and when the wire passes through the tip during welding, it has a radius of curvature in one direction. Unlike a spool-wound wire, the point of conduction from the inner wall of the chip to the wire is less likely to be fixed at a fixed point, and moves over a wide range of the inner wall of the chip. As a result, small sparks are generated here and there on the inner wall surface of the chip, making the arc unstable and forming a hard Fe-Cu alloy that increases the frictional resistance when the wire passes through the area, causing damage to the chip in a short period of time. It became clear that the supply would eventually stop.

(Means for Solving the Problems) The present inventors focused on this phenomenon, and investigated the properties of the wire and the surface of the wire in the wire loaded in the bail bag, where the current-carrying point often moves, and the transfer due to the attached substances. We experimentally investigated the relationship with feeding performance.

As a result, the amount of Ca in the lubricant remaining between the copper plating and the iron base under the plating, the amount of copper plating (thickness), the amount of oil attached to the wire surface, and the tensile strength of the wire. It has been found that the tensile strength at break greatly influences the feedability and other characteristics of the wire loaded in the bail bag. In other words, in the copper-plated steel wire with a diameter of 1.6 mm or less loaded in the bail bag, the amount of Ca interposed between the wire base and the wire surface plating layer satisfies equation (1) including the Cu plating thickness. ,
And the amount of oil adhesion is 0.30 to 1.20 g/10 kg
It has been discovered that a gas-shielded arc welding wire characterized by
Formula - Ca amount (mg/m2) ≦28.1 Cu plating thickness (t!m) + 22.5). In addition, by setting the tensile strength for solid wires and the tensile breaking load for franked wires within a certain range, it is possible to obtain a high-quality welded joint with minimal runout at the wire tip and no meandering of the weld bead. This is what I found. The basic effects of the amount of Ca interposed between the wire base and the wire surface plating layer are described in Japanese Patent Application No. 63-76 by the present inventor.
As already made clear in the specification of No. 193, the present invention relates to proposals regarding wires to be loaded into bailbacks, which have been increasing in recent years.

(Function) First, the reason why the amount of Ca interposed between the wire base and the wire surface plating layer in a copper-plated steel wire is regulated in relation to the Cu plating thickness is as follows.

That is, in bailback wires, the straightness is so good that movement of the energizing point between the inner wall of the chip and the wire occurs frequently with short sparks, but when the amount of Ca is large, the sparks tend to continue and become short due to the presence of Ca ions. The spark turns into a long spark that damages the chip in a short time. In addition, when moving to the Shindoden point, if Ca oxide exists in that area, current flow is inhibited and the welding arc suddenly breaks, etc. In this case, if the copper plating is thick, those The extent to which the phenomenon appears becomes smaller. Figure 1 shows this relationship, and the results of the long-term welding feedability test show that the higher the amount of Ca, the shorter the time for poor feedability, but the thicker the copper plating, the longer the time. It shows what will happen. The experimental conditions were JIS z33 wire.
12 YGWII applicable product, diameter 1.6mm, welding conditions are as follows:
At 400A, 32V, carbon dioxide gas 25 j2 /min,
This is downward bead-on-plate welding.

The test wire was taken out from a pail pack (for 350 kg) loaded with 50 wires with a general reverse twist.
Welding was carried out using a 6 m long conduit cable and a pistol torch via a conventional feeder. In addition, in order to conduct a long-term feedability test, the torch was fixed and the welding test plate was placed on a rotating jig and rotated so that weld beads formed in continuous layers. One cycle of welding is 5 minutes of continuous welding, and a maximum of 20 cycles are performed continuously.
It was determined whether welding was possible until the end without any problems in feed performance, whether welding was interrupted due to a feed failure midway through, or whether welding was not interrupted until the end but the arc became unstable. In this case, the amount of oil attached to the wire is 0.5 to 1.0g/10k
I went to g.

Although Fig. 1 shows experimental data for a wire diameter of 1.6 mm, other wire diameters of 1.4 mm and 1.2 mm were used.
Similar results were obtained for the shell and also for the flux-cored wire.

Ca remains in the form of lime soap, which is a lubricant used in wire drawing, or in the form of Ca0O after being thermally decomposed in the case of annealing. The method for quantifying the amount of Ca in a wire is to wash 100 g of wire with ethyl alcohol, cut it into lengths of 5 to 10 cm, boil the wire in dilute hydrochloric acid (7%) for 10 minutes, dissolve Ca, and filter it. , quantify Ca with an atomic absorption photometer. In this case, the steel base is also dissolved to some extent, but since the amount of Ca contained in general steel is small, all detected Ca amounts are taken as the amount of Ca interposed between the steel base and the wire surface plating layer.

Various methods can be considered to control the amount of Ca interposed between the wire surface plating layer and the steel base, but the most effective method is considered to be a pretreatment method before plating, and the bipolar electrolytic degreasing method is particularly effective. There is. However, in addition to this method, there are methods such as cathodic electrolytic pickling, normal anodic electrolytic degreasing, and cleaning methods after using lime soap as a lubricant (cleaning method with pressure water, mechanical methods such as brushing, etc.). It is effective to perform this in addition to the plating pretreatment method described above.

Controlling the copper plating thickness is easy and can be achieved by changing the plating size, plating current, time, etc.

It is necessary to limit the amount of oil adhering to 0.30 g / 10 kg or more in order to reduce the frictional resistance on the conduit and tip during welding and improve feeding performance, but in the case of pail pack wire, it is especially important to If it exceeds 1.20 g/10 glare, it is not preferable. This is because when loading the wire into the pail pack, the wire is passed through a straightening roller to ensure straightness, but if the amount of oil adhesion exceeds this level, the rollers tend to slip, causing small waviness to occur in the loaded wire. . This impairs the two characteristics necessary for bailback wire: no wire tip swinging and good long-term feeding performance.

The tensile strength of the wire affects both the long-term feedability of the bailback wire and the wire runout during welding in conjunction with the amount of oil adhesion and the amount of Ca. That is, when the tensile strength of each wire diameter is less than the lower limit value, the wire has low rigidity and tends to follow the bent portion of the conduit during feeding, and the wire is likely to become curly, causing the tip of the wire to run out. - If the brave limit value is exceeded, the feeding resistance will increase at the bent part of the conduit during feeding, worsening the feeding performance. The tensile strength of the wire also affects the amount of oil adhesion during manufacturing when loading the wire into a pail pack; if it is too low, it tends to cause waviness, and if it is too high, stable loading cannot be performed.

In the case of flux-cored wire, the inside of the wire is filled with flux, and the tensile strength, which overcomes the tensile breaking load by the cross-sectional area, cannot indicate the rigidity of the wire. Therefore, the tensile breaking load (kgf) of each wire diameter is calculated as is. stipulated. Note that these tensile strengths or tensile breaking loads can be set by changing the components of the raw wire or family pipe, the presence or absence of annealing in the manufacturing process, the annealing diameter, and the annealing conditions.

(Example) 0 Below, the manufacturing method of the wire of the present invention will be explained in detail in Examples.

First, the solid wire was made of raw cotton with a diameter of 5.5 mm, chemical components C: 0.07%, Si: 0.78%, Mn: 1.
A 50% hot-rolled steel wire was used as a raw wire, and after removing scale by mechanical descaling, it was pickled, immersed in a suspension of lime soap as a lubricant, coated and dried, and then treated with Na-based metal soap as a wire drawing lubricant. After drawing the wire to 2.0 to 2.4 mm using
Product diameter 1.2 ~ after plating pre-treatment process and plating process
1.6 mm inventive wire and comparative wire were produced;
The long-term welding feedability test described above was conducted. For flux-cored wire, chemical composition C: 0.05%, Si: 0
．． 01%, Mn: 0.40%, 12mm raw pipe is filled with flux, and Ca-based metal soap is used to
After drawing the wire to 4 mm, the product was subjected to the washing with pressure water, the presence or absence of annealing, the plating pretreatment process and the plating process shown in Table 1, and then the product diameter 1.2 to 1.6 mm and the comparison. Wires were manufactured, and the long-term welding feedability test described above (the determination method was also the same) was conducted. Table 1 shows the results.

1 Here, the annealing conditions were 550 to 750° C. for 3 hours using nitrogen as the atmospheric gas. The plating pretreatment and plating conditions were as follows.

1) Bipolar electrolytic degreasing 50A/piece, 7-12V solution NaO8100g/j2 Liquid temperature 80°C1 linear velocity 50-120m/min 2) Anodic electrolytic degreasing 110A/piece, 7-12V solution NaOH100g/j! Liquid temperature 60~70'C1 Linear speed 50~80m/min3) Cathode electrolytic pickling 110A/piece, 7~12V Solution HC4210~20g/12 Liquid temperature 25°C1 Linear speed 50~80m/min4) Plating 70~ 130A/piece, 7-12V solution KCN 5-20g/I! ,,liquid temperature 60°C
Wire speed: 50 to 80 m/min. Vegetable lubricant was used as the final wire drawing lubricant.

As shown in Table 1, wires manufactured under various manufacturing conditions and with wire characteristics that satisfy all the requirements of the present invention have been shown to have good results in long-term welding tests (O mark). Test No. 1-12).

However, as shown in the comparative wires (No. 13 to 15 and No. 20 to 21) where Ca amount - copper plating thickness does not satisfy the formula (1), wire feeding is interrupted (x mark) or interrupted. Although it did not occur, the arc became unstable (Δ mark).

In addition, Nos. 16 to 17 and No. 22 were discontinued due to an inappropriate amount of oil, and No. 19 was discontinued because the tensile breaking load of the wire was too low. No. 18 had too high a tensile strength, resulting in poor feedability and was discontinued.

(Effects of the Invention) According to the present invention, there is no problem with feeding performance even during long-term continuous welding with pail-packed wire, which has recently been frequently used in robot welding, etc., and there is no bead meandering due to tip deflection of the wire. It has become possible to weld with a welded part that has a uniform welded area.

4 5

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the results of a long-term welding feedability test when the amount of Ca interposed between the wire base and the wire surface plating layer and the copper plating thickness were varied. 6

Claims (1)

[Claims] (1) In a copper-plated steel wire with a diameter of 1.6 mm or less loaded in a pail pack, the amount of Ca interposed between the wire base and the wire surface plating layer includes the Cu plating thickness. (1) is satisfied, and the amount of oil adhesion is 0.30 to 1.
A steel plated steel wire for gas shielded arc welding, characterized in that the weight is 20g/10kg. Ca amount (mg/m^2)≦28.1Cu plating thickness (μ
m) +22.5 (1) (2) The steel plated steel wire for gas shielded arc welding according to claim 1, wherein the wire is a solid wire having a tensile strength within the following range. 70-100kgf/mm for wire diameter 1.6mm
＾For 21.4mm, 75-115kgf/mm＾21
．． 2 mm: 80 to 130 kgf/mm^2 (3) The steel plated steel wire for gas shielded arc welding according to claim 1, which is a flux-cored wire having a tensile breaking load within the following range. Wire diameter: 75-110kgf1.4 for 1.6mm
65-90kgf for mm 55-80kgf for 1.2mm