JPS6153151B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a vertical MIG welding method suitable for welding metals with good thermal conductivity such as copper and copper alloys.

(Prior art) Generally, in the vertical MIG welding method, as shown in Fig. 1, the base materials 1 and 1 to be welded are butted against each other with a gap 3 opened to accommodate the welding nozzle 2, and both sides of the welded part are It is surrounded by a pad 4 and its bottom is closed with a welding tab 5, and the welding wire 6 passing through the welding nozzle 2 is given weaving while being supplied with electricity to fill the welded part with molten metal.

(Problem to be solved by the invention) However, this vertical MIG welding method cannot be directly applied to metals with good thermal conductivity such as copper or copper alloys, and requires preheating with a heat source such as a burner or electric heat. Otherwise, a good weld cannot be obtained.

In view of this, an object of the present invention is to provide a vertical MIG welding method for metals such as copper and copper alloys that does not require preheating with a burner or the like.

(Example) Hereinafter, an example of the present invention will be described with reference to FIG.

In FIG. 2, base materials 7, 7 made of copper or copper alloy are butted together through a predetermined gap, and a welding nozzle 2 is inserted into this gap.
A welding wire 6 is inserted inside.

The butt bottom surface of the base material 7 is placed on a welding tab 8 having a U-shaped cross section in which a recess with a width corresponding to the width of the gap between the base materials is formed. A pair of dowels 9, 9, which have a tapered shape that gradually widens upward, and which when combined form a square funnel shape, are attached so as to be able to rise along the welding part, and the lower part of the dowel 9 has a weld bead. A pre-forming surface 9a forming a pre-forming shape is formed, and the upper part thereof forms a molten metal storage space in which molten metal 10 is stored.

In this way, the reason why a pair of tapered pads 9, 9 that gradually widen upward is used is to gradually decrease the volume per unit length of the molten metal stored therein toward the bottom. At the same time, as the temperature decreases, a higher temperature gradient is formed in the advancing direction, and the heat is effectively used for welding.
This is to facilitate the smooth movement of 9.

Further, each of the pads 9 has a hanging wire 1
1 and 11, by a lifting device (not shown).

Next, the effect will be explained.

First, the pad 9 is placed at the bottom of the welding part, and the welding nozzle 2 starts welding while horizontally weaving the electrically supplied welding wire 6.

In this way, weaving is performed on the base plate 1.
This is to supply and utilize the molten metal 10 as an ideal heat source by reducing the thermal gradient in the thickness direction, regardless of the thickness of the plate.

After a while after starting power supply to the welding wire 6, the molten metal 10 is stored in the pad 9 and overflows. When the welded part of the base metal 7 receives the necessary heat input for welding while maintaining this state, at that point the pad 9 is raised to the required size and the molten pool is transferred to the welded part that has not yet been heated. .

At this time, a weld bead preform 12 is formed on the exposed surface of the weld metal near the bottom of the welded portion by the preform forming surface 9a of the pad.

After raising the pad 9, the pad 9 is stopped until the required heat input is obtained at that position. Since this welding part has stored heat during the welding in the previous position, its downtime is shorter than in the previous position, so that less molten metal overflows from the dowel 9.

In this way, by raising the pad 9 by the required distance and applying the appropriate amount of heat to that position with the molten metal, welding can be performed. Since heat is accumulated in the welded part by welding, the stoppage time of the pad 9 gradually becomes shorter, and eventually it is sufficient to move the pad 9 slowly and continuously.

In addition, when carrying out this construction, oxides and impurities float to the surface of the molten pool that is melting at high temperatures, and the welding arc force and convection of the molten metal cause the wall side (second
There is a tendency to collect on the surface side of the pad 9 in the figure). Further, these oxides and impurities also cause defects in the weld metal. For this reason, the molten metal on the wall side is overflowed by the pad 9, and the oxides and impurities floating on the surface of the molten metal are caused to flow out of the molten metal, thereby shaping the bead shape of the joint. Not only that, but it also reduces the possibility of impurities and oxides getting mixed into the weld metal.

〔Effect of the invention〕

Since the present invention has the above-mentioned configuration, a higher temperature gradient is formed inside the pad in the direction of movement of the pad, so that heat is effectively used for welding, and the movement of the pad does not apply unnecessary force to the molten metal. Not only can the process be performed smoothly and uniform bead appearance can be obtained, but also the possibility of contamination of impurities and oxides into the interior of the bead can be reduced.

Moreover, regardless of the thickness of the plate, the temperature gradient in the thickness direction is reduced to ensure stable penetration.
It has various effects such as being able to perform stable welding and obtain good results.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a welding device for carrying out a conventional vertical MIG welding method, and FIG. 2 is a partial sectional view of a welding device for carrying out a vertical MIG welding method of the present invention. 1, 7... Base metal, 2... Nozzle, 6... Welding wire, 8... Welding tab, 9... Pad, 11...
...hanging wire.

Claims (1)

[Claims] 1. Cover the welding part of the base metal with a tapered pad that gradually widens upward, and while weaving the welding wire in the thickness direction of the base metal within the pad, a predetermined amount of molten metal is stored in the pad. A vertical MIG welding method characterized in that the welding is carried out while the welding is carried out while the welding is caused to overflow from the upper surface of the pad, and the pad is moved in the welding direction as welding progresses.