JPS606275A - Automatic overhead welding method - Google Patents

Abstract

PURPOSE:To perform overhead welding with higher stability and efficiency by synchronizing the current control of MAG welding with a composite core wire with weaving so that the arc length is extended to melt the groove wedge while the current is large and that the arc length is reduced to accelerate solidification while the current is small. CONSTITUTION:Welding current is synchronized with weaving and is impulsively controlled at a low frequency in the stage of welding automatically a groove in an overhead position by an MAG welding method using a composite wire having 1.2-1.6mm. diameter and using a gaseous mixture composed of Ar and CO2 as a shielding gas. The arc length is maintained long to melt widely both corners of the groove while the current is large in this stage and the arc length is maintained short to narrow the heating range by the arc and to accelerate solidification from the periphery of a molten pool while the current is small. The penetration in the corner parts of the groove is thus made thorough and the flat bead optimum for the overhead position is assured. The automatic continuous welding of the long-sized joint in the overhead position is thereby made possible and the efficiency and stability of welding are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention uses a thin composite wire with a diameter of 1.2 to 1.6 mm and a shield made of a mixture of argon and carbonate to form a joint with a groove. ``With regard to the upward automatic welding method that performs automatic welding in a two-sided position, the aim is to reduce the generation of vines, obtain a flat bead, and enable stable and sound continuous welding even on long joints. do.

Traditionally, the electrode consumable type Ganushield arc welding method in the top position has been unable to perform stable long continuous welding because the nupatta gets stuck in the welding torch and electrode tip.As an automatic welding method, the electrode non-consumable type A TIG welding method is used. However, the deposition speed of the TIG welding method is significantly inferior to the MTG welding method, MAG welding method, and electrode consumable Ganu shield arc welding methods, and from the viewpoint of welding efficiency, its use is limited to low-temperature steels, alloy steels, It is limited to structures with high-grade specifications, and in reality, general steel (1η structures) are welded by hand.

On the other hand, in order to enable highly efficient, stable, and sound continuous welding of long joints in an upward position using the consumable electrode type Ganushield arc welding method, it is essential to solve this problem.

■ Reducing the amount of force required to cause the occurrence of pine ivy.

■ Even in a two-sided position, the bead shape is less likely to become convex,
Must have a flat bead appearance.

■ Even with narrow groove angles, proactive measures are taken to prevent welding defects such as poor fusion and insufficient welding at the groove corners.

■ A high welding speed is maintained even in a two-sided position.

This invention was made with the above points in mind,
A top automatic welding method that automatically welds a joint with a groove in an upward position using a composite wire with a diameter of 1.2 am to 16 mm and a shielding gas consisting of a mixture of argon gas and carbon dioxide gas. In this process, the welding current is changed to large current and small current in a low cycle while synchronizing with weaving, and when the current is large, the welding arc length is kept long and both corners of the groove are melted widely, and when the current is small, The present invention provides an upward automatic welding method characterized by keeping the welding arc short and narrowing the heating range by the arc to promote solidification from the periphery of the molten pool.

Therefore, according to the present invention, even in electrode consumable Ganu shield arc welding, it is possible to obtain a flat bead with less occurrence of 7 spatters, and it is possible to perform stable and sound continuous welding even in long joints. Even with a narrow groove angle, welding defects such as poor fusion and insufficient welding do not occur at the groove corners.

Next, the present invention will be explained in detail with reference to drawings showing actual Mtv examples thereof.

Fig. 1 shows a cross section of a small-diameter composite wire, in which the inside of the composite wire (1) is filled with a lag-forming agent, an arc stabilizer, etc. (2) to form a smooth bead appearance. A copper plating layer (3) is formed on the outer periphery. and,
In the case of a solid wire, a thin nlug consisting only of desorption products is produced, but in the case of a composite wire, the bead forming ability is excellent, and a smooth bead appearance can be obtained even in a positive position. At the same time, the occurrence of pine ivy is extremely low. In addition, in top position welding using a solid wire, it is only possible to weld in a short-circuit transition mode, and low electric current i'ift: at most 150 Amps or less is required, whereas with a composite wire, Because the nullag prevents molten metal from dripping, high current welding of 20OA, mp or higher is possible.

Figure 2 shows the relationship between welding current and welding speed; in the figure, AI and A2 are composite wires of 1.2φ and 1.6φ, respectively; Bl and B2 are solid wires of 1.2φ and 1.6φ, respectively; C indicates a hand welding rod, and as is clear from the figure, when the wire diameter is the same, the composite wire has a higher current density and higher efficiency than the solid wire, and the composite wire has a higher current density and higher efficiency than the manual welding rod. The welding speed is approximately twice as high.

Next, by using a mixture of argon and carbonate gas as a shielding gas, the occurrence of welts is further reduced, and troubles due to welds do not occur even when continuous welding is performed over a length of several tens of meters.

Figure 3 is an explanatory diagram of the welding situation of the weaving synchronized low cycle PALNU upward position automatic MAG welding method, and the welding power source is used to adjust the welding current to the weaving as shown in (a) and (t)). The two currents, a large current and a small current, are synchronized and changed at low cycles. When the current is large, the welding arc length is kept long and both corners of the groove are melted widely and deeply, while when the current is small, the welding arc It has the function of keeping the length short and narrowing the heating range by the arc to promote solidification from the periphery of the molten pool.

In the same figure (b), (4) is the workpiece to be welded, (5
) is a torch, (6) is a composite wire, and the melted shape and bead appearance are as shown in FIG.

As a result, as shown in Figure 3 (C), the bead shape of each layer becomes a completely concave shape, and the smooth bead forming ability of the composite wire is also taken into account, resulting in a flat bead shape that is most ideal for welding in a positive position. It is possible to secure the following.

Further, since deep penetration is possible with a high current at both corners of the groove, narrow groove welding of about 300 is possible, and welding efficiency is improved due to the reduction in the groove cross-sectional area.

Furthermore, the structure to which the present invention is applied is effective in increasing the efficiency of welding long continuous joints in a forward position, such as seam/butt joints of bottom shell plates of ships, block joints of wing hoppers, etc.

In addition, the welding device embodying the present invention has a simple automatic traveling device having a weaving function and a traveling rail that are cleaned and set on the welding line of the object to be welded using a Macnet, and the traveling device is separate from the welding device. Connect with chi. The welding holes 1 and 1 are connected to a welding source having an arc conversion function, a wire feeding device, and a shield gun by cables.

In this case, the welding device is of a split-layer type and is lightweight, so it can be easily installed by one person.

Next, the welding conditions for welding a workpiece with a plate thickness of 22 mm using a composite wire with a wire diameter of 12 mm are shown in the table.

Note that single-sided welding can be performed using a backing with a root gap, but since the first layer is deep forged even with a zero root gap, sound welding is possible from the back side without digging.

[Brief explanation of drawings]

The drawings show an embodiment of the ``two-sided automatic welding method'' of the present invention,
Figure 1 is a cross-sectional view of the composite wire, Figure 2 is a relationship between welding current and welding speed, Figure 3 (a) is a waveform diagram of welding current, Figure (1) is an explanatory diagram of the welding situation, The figure (C) is a sectional view showing the melted state. (1)...Composite wire. Agent: Patent Attorney Ryuta Fujita Department Procedural Amendment (spontaneous) 1. Indication of the case, 1982 Patent Application No. 114500, 2. Name of the invention, upward automatic welding method, 3. Person making the amendment. Relationship with the case. Patent Application Person: Office 1-6-14 Edobori, Nishi-ku, Osaka Name (
511) Hitachi Zosen Corporation Representative Toshio Murayama 4 Agent Address 530° Address 2-9-4 Higashitenma, Kita-ku, Osaka 5 Subject of amendment Figure 1 of the drawing Contents of amendment 6 As shown in the attached sheet No. 1 Figure 446-

Claims (1)

[Claims] ■ Upward automatic welding that automatically welds joints with grooves in the top position using a thin composite wire with a diameter of 1.2 m from the shoulder to 1.6 mm and a shield made of a mixture of argon and carbonate ganuses. In the welding method, the welding current is synchronized with weaving and is changed to a large current and a small current at low cycles, and when the current is large, the welding arc length is kept long, both corners of the groove are melted widely, and when the current is small, the welding arc length is kept long, and both corners of the groove are melted widely. This automatic upper surface welding method is characterized by keeping the welding arc short and narrowing the heating range by the arc to promote solidification from the periphery of the molten pool.