JPS587390B2 - arc - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an arc welding method for welding thick plates of copper or copper alloy without preheating.

Conventionally, TIG and MIG arc welding force methods have been used for arc welding of copper or copper alloys, but both
There is a problem when the plate thickness is thick (for example, 10 mm or more).

That is, in the conventional MIG arc welding method, the diameter of the welding wire is 1.6M or 2.4M, and the current used is about 250 to 600A.

If welding is performed without preheating, the weld metal and the material to be welded are insufficiently fused, resulting in welding defects such as poor penetration, poor fusion, and overlapping, making it impossible to obtain a good bead shape. .

In addition, when preheating (up to 600°C) is required, the preheating process before welding requires a lot of time, and it is extremely difficult to weld while keeping the preheating temperature uniform at all times, resulting in a uniform bead cross section. There were many problems such as it was difficult to obtain the desired shape, distortion occurred frequently, and hot cracking was likely to occur in the heat-affected zone and bond area of the welded material.

In order to improve these fusion defects, attempts have been made to mix N2 into Ar as a shielding gas to increase the potential gradient, or to weld with N2 alone, but spatter tends to occur and tunneling occurs in the bead. There were concerns about the welding results, such as the possibility of blemishes occurring.

In addition, for plates with a thickness of 10 mm or more, it is still not sufficient to obtain a good bead cross-sectional shape without any residual heat, so this welding force method using N2 is put into practical use. has not yet been reached.

On the other hand, if the conventional welding wire diameter is 1.6 mm or 2.4 mm,
When using a large current of 00A or more, due to the high current density,
In the arc, harmful fumes peculiar to copper alloys are generated, so it was necessary to avoid using large currents of 600 A or more.

The welding method of the present invention solves the above-mentioned conventional problems at once, and uses an inert gas containing He of coefficient 50 or more as a shielding gas, a welding wire diameter of 2.8M or more, and a welding current of 2.8M or more. This paper proposes an arc welding force method for welding thick plates of copper or copper alloy without preheating, using a current density of 600 A or more and a welding wire current density of 100 A/mm or less.

Hereinafter, the arc welding method according to the present invention will be explained in detail.

Fig. 1 is a diagram showing the relationship between the cross-sectional area of the welding wire and the welding current, and the range A shown at the bottom left of the figure is the conventionally applied range. The range B shown in the upper right corner is the range applied to the welding force method of the present invention.

A1 to A5 in Figure 2 are the conditions shown in A1 to A5 in Table 1, using a thick plate of tough pitch copper with a thickness of 20 layers as a shield gas and only Ar gas. The cross-sectional shape of a bead is shown when welding is performed by passing a large welding current of 850 A through an acid copper welding wire and varying the preheating temperature.

The reservoir 1 in the figure is an example in which no preheating is performed, and a good bead cross-sectional shape as shown in the figure cannot be obtained.

On the other hand, as shown in columns No. 2 to No. 5 in the same table, as the preheating depth increases sequentially, the melting cross section increases as shown in No. 2 to No. 5 in the same figure, so the apparent change when the preheating temperature is changed If the arc length (the shortest distance between the tip of the welding wire and the surface of the base metal) is kept constant, the force at which the preheating temperature is high will cause the actual arc length to increase, which will also increase the arc voltage and increase the heat input. As shown in A3 and 5 in the same figure, a good bead cross-sectional shape can be obtained.

As is clear from these results, even if a large diameter wire is used and a large current is used, a good bead cross-sectional shape cannot be obtained when a thick copper plate is welded using only Ar gas without preheating.

No. 6 to No. 10 in Figure 3 correspond to No. 6 to No. 10 in Table 2.
Under the conditions shown in Step 10, a large welding current of 850 A was applied to a thick plate of tough pitch copper with a thickness of 20 mm through a deoxidized copper welding wire with a diameter of 4.0 m, and Ar gas and He gas were used as shielding gases. The cross-sectional shape of the bead is shown when the mixing ratio is changed and welding is performed without preheating.

In this case, if only Ar gas is used as the shielding gas, a good bead cross-sectional shape cannot be obtained as shown in FIGS. 3 & 6 (same as A1 in FIG. 2).

However, as shown in columns A7 to A10 of the same table, when the mixing ratio of He gas mixed with Ar gas as the shielding gas is increased by one order, the bead shape gradually changes to a better shape.

When the mixing ratio of He gas is 25%, it cannot be said that the bead shape is still good, but when the mixing ratio of He gas is 50%
(In this case, a good bead cross-sectional shape can be obtained in all cases.

Therefore, according to the present invention, even without preheating as shown in A8 to A10, if the He turtle is heated to more than soql, the A
It is possible to create a bead cross-sectional shape similar to that in the case of preheating shown in 3 to &5.

As described above, with an inert gas containing less than 50% He gas, a thick copper plate with a thickness of 10 wIl or more cannot obtain a good bead cross-sectional shape without preheating.

Therefore, in the arc welding method of the present invention without preheating, an inert gas containing 50% or more of He gas is required.

Ar gas is usually used as the inert gas other than He gas, but He gas alone may be used.

Next, when the welding current was less than 600 A, even if an inert gas containing 100% He gas was used, a good bead cross-sectional shape could not be obtained with a copper plate having a thickness of 10 mm or more without preheating.

Therefore, the arc welding method of the present invention without preheating has a
If so, it is necessary to increase the welding current to 600A or more.

Further, when the welding wire diameter is less than 2.8M, when a welding current of 600A or more is passed, the current density exceeds 100A/mm, and harmful fumes peculiar to copper alloys are generated.

Therefore, in the arc welding method of the present invention, the welding wire diameter needs to be 2.8 mm or more.

FIG. 4 is a photograph showing the shape of a bead in an example when flat plates having a thickness of 20 mm are butt welded, and the welding conditions at that time are as follows.

Welding wire: Deoxidized copper, wire diameter: 40 mm Material to be welded: Tough pitch copper, plate thickness: 20 mm Shielding gas: Mixed gas of 50% Ar and 50% He 80l/groove π Welding current: 1000A Arc voltage: 36 ■ Welding speed = 30crrL〆No preheating Fig. 5 is a cross-sectional view of another example in which welded materials 1 and 1' with different thicknesses are welded at an angle, and the welding conditions are as follows. There are eight.

Welding wire: Deoxidized copper, wire diameter 4.0wIl Material to be welded: Tough pitch copper Shielding gas: Mixed gas of 50% Ar and 50% He 50l/groove π Welding current: 850V Arc voltage: 35■ Welding speed: 2 5 cm. /vu. yt without preheating Fig. 6 is a diagram showing a cross section of another example in which welded materials 1 and 1' having different plate thicknesses are butt welded, and the welding conditions are the welding speed of 25 cm/mm in the case of Fig. 4. <30cm/
The other conditions are the same as in the case of FIG. 5.

8 In FIGS. 5 and 6, 2 is a bead.

According to the present invention: (1) Since no preheating is required, the pre-welding process is significantly simplified.

(2) Since high current is used, welding efficiency is improved (
3) High-temperature preheating is not required, so hot cracking does not occur in the heat-affected zone and bond area. (4) There is no thermal strain caused by preheating, so strain relief after welding is not required. (5) Welding By simplifying the process, costs can be reduced. (6) Since there is no preheating, it is easy to automate welding. (7) Does the low current density generate fumes that are harmful to the human body? There are many effects such as not having that.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the applicable range of the conventional arc welding force method and the applicable range of the arc welding force method according to the present invention, and No.
1 to No. 5 are cross-sectional shapes of each bead when the preheating temperature is changed using only Ar gas, 6 to &10 in Fig. 3 are cross-sectional shapes of each bead when the gas ratio is changed without preheating, FIG. 4 is a photograph showing an embodiment of the arc welding force method according to the present invention, and FIGS. 5 and 6 are cross-sectional views showing embodiments of the arc welding force method according to the present invention. 1, 1'... Material to be welded.

Claims (1)

[Claims] 1. In the arc welding force method for welding copper or copper alloy thick plates with a thickness of 10 mm or more using a shielding gas, an inert gas containing 50% or more He is used as the shielding gas, and the welding wire diameter is 2. 8mm or more, the welding current is 600A or more, and the current density of the welding wire is 10
An arc welding force method characterized by welding at 0 A/mm2 or less and without preheating.