JPS6120391B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a narrow gap MIG welding method in which a control gas other than a shielding gas is sprayed onto a molten pool to control the bead shape, that is, the shape of the molten pool.

Generally, in the narrow groove MIG welding method, welding defects may occur on the sidewalls of the groove due to poor fusion, and one of the causes of this is thought to be a defective bead shape in the previous layer.

This invention takes the above points into consideration and improves the bead shape in narrow gap MIG welding. Next, this invention will be described in detail with reference to drawings showing embodiments thereof.

First, FIG. 1 shows a state in which plastic deformation is imparted to the weld core wire, and the weld core wire 1 is guided from the wire reel through the wire straightening device to the wire feeding device 3 via the curvature imparting device 2, and the weld core wire is introduced into the weld tip. 4 will be introduced.
The curvature imparting device 2 includes three rolls 6 on the substrate 5.
are rotatably arranged in a staggered manner, and as the core wire 1 passes through each roll 6, plastic deformation of a predetermined curvature is imparted to the core wire 1 itself. Then, the entire curvature imparting device 2 is rotated at a constant speed by the motor 7, and the core wire 1 is imparted with a 360 degree continuous curvature deformation, that is, a spiral deformation.

Next, the core wire 1 is introduced into the contact tube by a wire feeding device 3 equipped with a roll 9 rotated by a motor 8, and is led out from the tip 4.
is restored to the previously given curvature due to the elasticity of the core wire 1, and the tip of the core wire 1 rotates with deviation from the tip of the tip 4, and the arc generated from the tip of the core wire 1 It becomes a rotating arc commensurate with the curvature of 1,
The trajectory becomes as shown in 10.

Therefore, without shaking the chip 4,
The welding arc can be weaved, sufficient penetration is achieved, and the discharge of harmful gases from the molten metal is also facilitated.

Next, FIG. 3 showing a front view and a bottom view of the welding nozzle portion, and FIGS. 2 and 4 showing the gas supply state will be described.

The plastically deformed core wire 1 is inserted into the chip 4 through the contact tube 4', and a welding power supply terminal 11 is provided integrally with the chip 4, and a water cooling pipe 12 for cooling the chip 4 is attached. has been done. Further, a shield gas nozzle 14 is attached to the chip 4 by a fitting 13, the opening of which is formed into a horizontally elongated hole 15, a control gas nozzle 16 is provided in the elongated hole 15, and a shield gas supply port 1 is provided.
A shielding gas 14' is supplied from 7, and a control gas 16' is supplied from a control gas pipe 18. Further, a water cooling pipe 19 for cooling is attached to the shield gas nozzle 14. And control gas 1
6' is sprayed onto the rear end of the molten pool 20.

Therefore, the center of the molten pool is depressed, and the molten metal accordingly moves to the groove sidewalls, increasing its penetration into the groove sidewalls.

Next, experimental results regarding the control gas and bead shape will be explained.

Now, as illustrated in Fig. 5 a and b, the amount of concavity of the bead is d, and the inner diameter of the control gas nozzle is
When using argon gas as the control gas with a diameter of 2.7, there is a gap between the control gas flow rate Q and the bead depression d.
The results shown in Figure 6 were obtained, and the control gas flow rate Q was 3.
/min or more, the indentation shown in FIG. 5b occurred.

Next, the inner diameter of the control gas nozzle is 2.7φ and 5.0φ.
Control gas flow rate V and bead depression d in the case of
Figure 7 shows the relationship between

That is, as is clear from the figure, it was found that there is a correlation between the control gas flow rate and the amount of concavity of the bead.

As described above, the narrow gap MIG welding method of the present invention includes a curvature imparting device in which several rotatable rolls are arranged in a staggered manner on a base body and the base body is rotated in one direction by a motor. Insert the core wire into the curvature imparting device to apply helical plastic deformation to the weld core wire, guide the weld core wire through the chip, and provide a control gas nozzle in the shield gas nozzle having an elongated hole. , in addition to the shielding gas from the shielding gas nozzle, a control gas from the control gas nozzle is sprayed onto the rear end of the molten pool to dent the center of the molten pool and transfer the molten metal to the side wall of the groove; It is characterized by increasing the penetration of the side wall of the groove.

Therefore, according to the present invention, the curvature imparting device restores the core wire led out from the chip to the previously imparted curvature due to the elasticity of the core wire, and the tip of the core wire is deflected from the tip of the chip. The arc generated from the tip of the core wire becomes a rotating arc that matches the curvature of the core wire, and the welding arc can be weaved without shaking the chip, ensuring sufficient penetration. Emissions of harmful gases in the molten metal are also encouraged.

Furthermore, since the control gas from the control gas nozzle installed in the long-hole shield gas nozzle is blown to the rear end of the molten pool, the center of the molten pool is depressed, and the molten metal accordingly The welding is transferred to the sidewall portion, and penetration of the groove sidewall portion increases, thereby preventing insufficient penetration of the groove sidewall portion.

[Brief explanation of the drawing]

The drawings show an embodiment of the narrow gap MIG welding method of the present invention, and FIG. 1 is an explanatory diagram of imparting plastic deformation, and FIG.
The figure is a front view of the welding nozzle part, Figure 3 is a bottom view of a part of Figure 2, Figure 4 is an illustration of gas supply, Figures 5a and b are illustrations of bead shape, and Figure 6 is an illustration of the bead shape. FIG. 7 is a diagram showing the relationship between the control gas flow rate and the bead shape. FIG. 7 is a diagram showing the relationship between the control gas flow rate and the bead shape. 1... Welding core wire, 2... Curvature imparting device, 3...
Supply device, 4... Chip, 5... Base, 6... Roll, 7... Motor, 14... Shield gas nozzle, 15... Long hole, 16... Control gas nozzle, 2
0... Molten pool.

Claims (1)

[Claims] 1 Equipped with a curvature imparting device in which several rotatable rolls of the base body are arranged in a staggered manner and the base body is rotated in one direction by a motor, the weld core wire is inserted into the curvature imparter device, and the weld core wire is inserted into the weld core wire. A control gas nozzle is provided in a shielding gas nozzle which imparts helical plastic deformation, guides the weld core through the chip, and has a long hole, and in addition to the shielding gas from the shielding gas nozzle, the control gas nozzle The control gas from the molten pool is blown to the rear end of the molten pool, the central part of the molten pool is depressed, the molten metal is transferred to the side wall of the groove, and penetration of the side wall of the groove is increased. Narrow gap MIG welding method.