JPS6319271B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves welding a material with good thermal conductivity such as copper or copper alloy in an inert gas using a welding wire as an electrode.
This invention relates to a downward MIG welding method in which an arc is generated between an electrode and a base metal, and welding is performed while continuously feeding a welding wire.

Generally, when performing downward MIG welding (hereinafter referred to as MIG welding), the base metal has good heat conduction, so the amount of the base metal melted by the arc is extremely small, making welding difficult. To assist with this, it is common practice to preheat a large area of the base material to a high temperature using another heat source, such as a burner.

FIG. 1 shows the process of forming a weld bead.
In FIG. 1, welding progresses in the direction of the arrow.

A welding wire 2 is provided on the base material 1, and a fusion zone 1a in which the base material 1 and the wire 2 are fused is formed directly below the wire 2, and a surplus 3 is formed behind the fusion zone 1a.

The welding wire 2 transfers to the base metal side while melting, and the accumulated molten metal has a shape determined by its surface tension, viscosity, etc., and eventually solidifies sequentially as the arc heat source moves away to form a weld bead.

Here, the characteristic disadvantages when welding materials with good thermal conductivity such as copper are: 1. The amount of welding wire deposited is large compared to the molten part of the base metal, and the molten metal is transferred to the unmelted part of the base metal. Covers. That is, overlapping weld beads result, and the base metal in the overlapped portion remains unmelted, resulting in a welding defect.

2 In the case of steel, etc., the base metal can be processed by the gouging method, which involves creating an arc between the base metals with a carbon electrode, melting part of the base metal, and blowing away the molten metal with compressed air, but in the case of copper, for,
Gouging is not possible, and the only methods available are grinding with a grinder, etc., or cutting. Therefore, the number of man-hours required for finishing the extra welding by MIG welding becomes extremely large, and there are other problems such as deterioration of the material quality of the base material due to preheating.

In view of the above, the present invention provides a method for downward MIG welding of copper and copper alloys, which performs welding without preheating, eliminates excess welding after welding, increases penetration depth, and improves the quality of the welded part. The purpose is to

Embodiments of the present invention will be described below with reference to FIGS. 2 to 6.

In FIGS. 2 to 4, a molten metal reservoir 4a for storing molten metal is provided in a support frame 4 made of a material such as carbon or ceramic, and this molten metal reservoir 4a is opened in the vertical direction. One wall defining the periphery of the molten metal reservoir 4a is cut lower than the other peripheral walls to form a discharge portion 4b.

The support frame 4 has the melt discharge part 4 on the base material 1.
b is placed on the rear side with respect to the welding direction, and the welding wire 2 is placed above the molten metal 4a, but its position is as shown in FIG.
It is located slightly behind the center of the molten metal reservoir 4a, and the melting area Sa on the base material 1 is the front wall 4c of the molten metal reservoir 4a.
It is designed so that it does not protrude further forward. Also,
As shown in FIG. 5, the base metal 1 is installed so as to be inclined so as to have an upward angle θ of 5 degrees or more in the direction of welding progress. Gravity acts effectively on the metal, making it easier to be ejected.

Next, the effect will be explained.

When an arc is generated in the molten metal reservoir 4a provided on the support frame 4, the welding wire 2 moves to the molten metal reservoir 4a of the support frame 4 while melting, and accumulates over time. However, the amount of molten metal is
When the height becomes equal to or higher than b and moreover exceeds the height that balances the surface tension of the molten metal, the molten metal flows out from the discharge portion 4b. At this time, as the amount of molten metal flowing out from the discharge portion 4b increases, the temperature of the molten metal accumulated in the cover frame 4 is heated by the arc and rises. Therefore, the temperature of the base material 1 also rises, the range of the fused portion 1a of the base material gradually becomes wider, and the penetration depth also increases.

As shown in FIGS. 3 and 4, when the range of the molten part 1a of the base material becomes wider than the other peripheral walls excluding the front wall 4c of the molten metal reservoir 4a of the backing frame 4, the backing frame 4
Then, the welding wire 2 is advanced to proceed with welding.
This is because if the support frame is moved forward after the melting range of the base metal has expanded beyond the front wall 4c, the movement will not be carried out smoothly, and the melting range of the base metal will be narrower than the molten metal reservoir 4a. In such a case, a semi-solidified portion or a solidified portion may be formed in the molten metal on the base material 1, making it difficult to move the support frame 4. The molten metal discharge part 4b can form a weld bead on the lower surface in contact with the base material 1. That is, the molten metal discharge section 4b
A part of the lower surface in contact with the base material 1 is the melted part 1a of the base material.
In addition, the other part of the lower surface is in contact with the coagulation part.
Therefore, the surface molding of the molten part 1a of the base material is performed using the support frame 4.
This is done on the lower surface of the molten metal discharge part 4b, and it is easy to eliminate any surplus, and it is also easy to add a desired amount of surplus.

When the welding speed is slowed down, the discharge part 4b of the support frame 4
Although the amount of molten metal discharged from the base material 1 increases, the temperature of the molten metal accumulated in the support frame 4 increases, and the depth of penetration into the base material 1 can be increased. Therefore, full penetration welding, which melts the entire thickness of thick plates without preheating, can be easily performed.

However, as the welding speed becomes slower and the amount of discharge increases, the height of the molten metal discharged from the molten metal discharge part 4b that adheres to the welded part of the base metal 1 and its vicinity becomes higher. , when the height exceeds the height of the discharge section 4b, the support frame 4
It becomes difficult for molten metal to be discharged from the base metal, and the amount of molten metal that accumulates increases, which may cause problems such as changes in the amount of penetration into the base material. In this case, the discharged metal accumulated at the rear of the discharge portion 4b may be removed by tapping occasionally to peel it off.

If the lower surface 4d of the discharge part 4b is raised above the surface of the base material as shown in Fig. 6, the desired reinforcement can be applied, and welding can be performed without defects such as poor fusion. Can be applied to internal welding.

Since the present invention is configured as described above, in conventional downward MIG welding, molten metal is layered, the amount of molten metal on the base metal increases, and the arc acts from above the thick layer of molten metal, so the base metal However, according to the present invention, the amount of molten metal that covers the unmelted parts of the base metal is reduced, and the arc heat source is reduced. The distance to the base metal can be brought sufficiently close, and the penetration depth of the base metal can be made sufficiently large depending on the temperature of the molten metal without preheating. Moreover, since the base metal is installed at an angle, gravity effectively acts on the molten metal discharged from the discharge part of the molten metal reservoir, making it easier to discharge, and the discharged metal scatters backward. Problems such as discharged metal accumulating near the discharge section are eliminated. It is possible to perform downward MIG welding without leaving any excess metal, significantly reducing processing costs, and producing defect-free welded joints of high quality copper and copper alloys.

[Brief explanation of the drawing]

Fig. 1 is a conventional downward MIG welding state diagram, Fig. 2 is a perspective view showing the welding method according to the present invention, Fig. 3 is a sectional view of the welding state according to the present invention, and Fig. 4 is a diagram showing the welding state in the welding state according to the present invention. FIG. 5 is a plan view showing the relationship between the melting range of the frame and the base material, FIG. 5 is a sectional view when the base material is tilted, and FIG. 6 is a sectional view showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Base metal, 1a... Melted part of base metal, 2... Welding wire, 3... Remains, 4... Backing frame, 4a...
Molten metal reservoir, 4b...discharge part.

Claims (1)

[Scope of Claims] 1. A support frame equipped with a molten metal reservoir for storing molten metal is placed on a base material installed at an angle with respect to a horizontal plane, and a welding wire is placed above the molten metal reservoir. A downward MIG welding method, characterized in that the welding is performed upward along the slope of the base metal while discharging excess molten metal from the rear side of the molten metal reservoir in the welding progress direction. 2. Claim 1, characterized in that a welding wire is installed above the rear side of the molten metal pool so that a portion of the base material on the front side in the welding progress direction from the front wall of the molten metal pool does not melt. Downward MIG welding method as described.