JPS5846400B2 - Manufacturing method of solid wire for gas shield arc welding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a solid wire for gas-shielded arc welding, and is aimed at improving wire feeding performance, particularly preventing wire buckling and surface abrasion in a welding torch. be.

Generally, what is called a solid wire for gas shielded arc welding contains Si or Mn as a deoxidizing agent and is easily work hardened during wire drawing.

Then, when the work-hardened wire is further drawn,
Since wire breakage and die damage are likely to occur, the final product wire is limited to a certain limit of work hardening.

The degree of work hardening is usually expressed by the average tensile strength value of the wire, and the flat part tensile strength value when this certain limit of work hardening is reached is about 110 kg/-.

When the average tensile strength value reaches this value, it is once heat-treated to return it to a value of 65 to 75 kg/- and processed again to obtain the required product wire diameter.

That is, conventional wires have an average tensile strength of 75 to 110 kg/m due to manufacturing reasons! ttic finish, but when this wire is reviewed from the usage perspective, there are various problems.

Fig. 1 is a diagram showing the principle of use of solid wire for gas-shielded arc welding. The wire 1 is fed into the welding torch 4 by the feed roller 2 through the wire holder and the mouth 3. If the wire 1 is subjected to a load at the tip, the wire 1 may buckle in the welding torch 4 or the wire receiver may buckle at the mouth 3.

This tendency is particularly pronounced when the wire diameter is small, and the wire receiver may even damage the opening 3 and the welding torch 4.

For this reason, various improvements have been made on the welding equipment side in order to solve this problem. For example, the inner diameter of the wire receiver and the conduit tube in the welding torch 4 and the mouth 3 have been made smaller to prevent buckling. It was designed to be.

However, as semi-automatic welding methods have become popular in recent years, the number of cases in which semi-automatic welding torches are bent and used in narrow welding areas has increased, and the demand for complete prevention of wire buckling has become even greater.

This is because if the inner diameter of the conduit tube is made too small, the frictional force between the wire and the inner wall of the conduit tube will increase, causing severe abrasion of the wire surface. This is because they are no longer able to be sent.

Therefore, the inventors conducted various studies and found that it is possible to completely prevent wire buckling and wire feeding by making the average tensile strength of the wire itself significantly higher than the conventional value and keeping the hardness of the wire surface within a certain range. We have determined that this will lead to improved feeding performance.

Table 1 below shows the test wires used in this experiment, wire A-
D is the conventional wire, E~■ is the prototype wire, among which G
, H, I are wires according to the present invention.

Further, FIGS. 2a and 2b show the measurement results of the tensile strength of the test wire, and FIG. 3 shows the measurement results of the surface hardness of the test wire.

In addition, Table 2 below examines the frequency of wire buckling by suddenly closing the tip end during welding, and it shows that the amount of wire used is small and there is no accumulation of scraps on the conduit tube. Buckling occurs only once with conventional wire, but as the amount of wire used increases and the amount of scraping on the conduit tube increases, the number of buckling occurrences increases dramatically, making it impossible to weld satisfactorily. .

Even with the prototype wire, if the tensile strength is as high as E, it will not buckle only during the initial period, but after a short period of use, buckling will easily occur.

Also, if the surface hardness is high as in F, there will be less scraping, but buckling cannot be completely prevented.

With the G, H, and I wires of the present invention, buckling can be prevented in this way, and in terms of wire feeding performance, compared to the motor current waveform of the conventional wire C as shown in FIG. Fifth
As shown in the figure, it has a smooth waveform (wire ■) with a small current value, and it can be seen that it is several steps better.

That is, as in the present invention, the wire average tensile strength is 120
kg/evi1 or more and 170 kg/- or less, and wires with average plane hardness of Vickers hardness of 250 or more and 450 or less have very low buckling frequency, can withstand long-term wire use, and have high feedability. As a result, stable welding work can be performed even when the welding torch is bent in a narrow welding area, and a good welding result without defects can be produced.

Here, in order to give the wire work hardening that exceeds the conventional concept and to achieve the specified surface hardness, it is necessary to pass it through many dies with a small area reduction ratio and to use a high-strength diamond in the die. Slowly draw the wire using dies, etc.

However, even with this method, the average tensile strength is 170*g
/rrty! If it exceeds this point, no matter how small the area reduction rate is, the wire will break at this point.

When the average wire surface hardness exceeds Hv=450,
No matter how many diamond dies there are, the dies will become extremely rough and scratches will occur, making wire drawing impossible.

Next, in order to effectively manufacture the wire of the present invention, among the hot-rolled raw wires, the cooling process during manufacturing is sufficient and the average tensile strength is set to 60 kg/mit or less.4, 5-6.
A method is used in which a 0φ wire is drawn into a predetermined 0.6φ to 2.0φ wire only by wire drawing without performing any intermediate heat treatment such as annealing.

This is because the tensile strength of the original wire is lower than that of the conventional wire, which uses a raw wire with an average tensile strength of 65 to 70 kg/- and is annealed with an intermediate wire diameter of 2.0 to 3.0 φ. This is because a large amount of steel can be obtained, and continuous work hardening can be performed without annealing.

In addition, sulfur is added as a lubricant during this wire drawing process.
When a wire drawing lubricant containing 20% is used, the wire drawing speed can be increased, the die life can be extended, and the manufacturing cost can be reduced.

Here, the reason why the sulfur content was set to 1 to 20φ is that sulfur content of less than 1% has no effect on improving the sulfur resistance.
This is because if it exceeds 0%, there is a high risk of weld cracking due to sulfur intrusion into the weld metal part.

As described above, when the wire according to the present invention is used as a solid wire for gas-shielded arc welding, the prevention of wire buckling and scraping gas accumulation is removed, and the tip fusion of the welding torch, which is induced by wire buckling and scraping, is prevented. Wear and wire feed roll wear, wire receiver prevents mouth breakage,
This can extend the life of the welding equipment and increase the reliability of welding work.

[Brief explanation of the drawings] Figure 1 is a front view of the device showing an example of the use of solid wire for gas-shielded arc welding, Figures 2 a and b are custom diagrams of wire tensile strength versus wire length, and Figure 3 is a wire FIG. 4 is a motor current waveform diagram using a conventional wire, and FIG. 5 is a motor current waveform diagram using a wire according to the present invention.

Claims (1)

[Claims] I A method for manufacturing a solid wire for gas-shielded arc welding containing deoxidizing components such as Si and Mn, in which a hot-rolled raw wire of 4.5φ to 6.0φ with an average tensile strength of 60 to 97 m4 or less By drawing the wire without heat treatment such as intermediate annealing, the average tensile strength of the wire can be increased to 120 k.
g/vt1. The average surface hardness of the wire is 250 on the Vickers hardness.
A method for manufacturing a solid wire for gas shielded arc welding, characterized in that the number is 450 or less. 2. The method for manufacturing a solid wire for gas shielded arc welding according to claim 1, characterized in that a wire drawing lubricant containing sulfur of 1 to 20 φ is used during wire drawing.