JPS61108471A - Mig welding method - Google Patents

Abstract

PURPOSE:To stabilize an arc, to suppress spatters, and to form a beautiful bead by vibrating a droplet generated in the tip part of a welding wire, and shifting the droplet to a base metal side before it grows to a large drop state. CONSTITUTION:By applying a voltage to an exciting coil 12 from an alternating field generating power source 13, an alternating field is applied in the direction orthogonal to the feed direction of a wire 4 to the tip part of the welding wire 4, by which a droplet 10 generated in the tip of the wire 4 is vibrated. The droplet 10 is shifted to a base metal side before it grows to a large drop state. Accordingly, an arc is stabilized, and welding of a high quality is executed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to improvements in MIG welding methods.

[Conventional technology]

The MIG welding method is a type of gas shielded arc welding. This welding method will be explained with reference to the welding example shown in FIG. In Fig. 7, 1 is weld metal, 2 is base metal, 3 is welding arc, 4 is welding wire, 5 is power supply tip, 6 is shielding gas, 7 is nozzle, 8 is wire supply roller, 9 is DC welding It is a power source.

Applying a DC voltage between the power supply tip 5 and the base metal 2 from a DC welding power source (generally, the power supply tip 5 is set to positive polarity),
A consumable welding wire 4 made of almost the same material as the base material 2 is fed to a feed roller 8.
The base material 2 and the welding wire 4 are melted in an inert shielding gas 6 such as argon or helium, and then welded by joining them together. The advantage of this welding method is that it can be applied to welding almost all metals, and it can achieve welding efficiency 2 to 3 times higher than that of TIG welding. As shown in FIG. 8, the droplets 10 are extremely fine, the welding arc 3 is stable, the bead surface forms continuous beautiful waves, and a beautiful appearance is obtained with less spatter. However, in the small N region, the droplet 1o becomes larger and falls as shown in FIG.

During this time, the droplet 10 moves irregularly at the tip of the male contact wire 4 and repeatedly shorts with the base material 2. Therefore, the beat becomes worse and the occurrence of spatter increases.

As a result, it becomes impossible to use thin plates (approximately 3#1I11 or less) in a low current range.

For this reason, a pulse arc welding method as shown in FIG. 10 has been developed. In FIG. 10, the horizontal axis shows time (T), and the vertical axis shows welding current (1). Ib is a DC current with an almost smooth waveform obtained from a normal DC current, etc., and is called the base current, Ip is a pulse current superimposed on the base current, and Ia is the DC current obtained by using the above-mentioned 1b and I.
This is the average value of the sum of p, which corresponds to the welding current commensurate with the wire feeding speed. On the other hand, IC is the critical current value for the wire. In addition, at ■ in Fig. 10, when the welding current I exceeds the critical current Ic, the droplet 10 at the tip of the welding wire 4
is squeezed by the pinch effect (electromagnetic pressure caused by current).

In (2), the pinch effect becomes larger than the surface tension of the droplet 10, and the droplet 10 separates from the tip of the welding wire 4 as a small particle and rushes into the molten pool at a high speed. In cases (2) and (2), a new droplet 10 begins to grow, but the current is as low as Ib, and the droplet cannot become large. ■′ is the same as ■. Such 10th
According to the welding method shown in the figure, the droplets 10 can be made finer by using a welding current having a peak wave (pulse current) in a current range below the critical current 1c.

[Problem that the invention seeks to solve]

However, the pulsed arc welding method requires a pulse generating power source, which increases the price of the equipment.In addition to the conventional welding current and arc voltage (average value), the pulsed current
Setting the welding conditions becomes complicated because of the addition of parameters such as peak value), pulse width, pulse frequency, and base current.

The present invention aims to provide a MIG welding method that can perform good welding in a low current range without using an expensive pulse generating power source or the like.

[Means for solving problems]

Hereinafter, the present invention will be explained in detail with reference to FIGS. 1 to 3. Incidentally, the same members as those shown in FIG. 7 described above are given the same reference numerals and the explanation thereof will be omitted.

11 in the figure is a square-shaped magnetic body arranged so that the part where the alternating magnetic field is generated is located near the tip of the welding wire 4;
An excitation coil 12 is wound around this magnetic body 11 .

An alternating current generating power source 13 is connected to this exciting coil.

As shown in FIGS. 2 and 3, an alternating magnetic field is applied to the tip of the welding wire 4 in a direction perpendicular to the feeding direction of the wire 4 by applying a voltage to the excitation coil 12 from the alternating magnetic field generating power source 13. The droplet 10 formed at the tip of the wire 4 is vibrated. In other words, when the magnetic field formed in the gap of the magnetic body 11 is in the direction B1 from P to Q, the current is flowing from the welding wire 4 to the base metal 2, so the droplet 10 is exerted a force in the direction Fl. receive. Conversely, when the magnetic field is in the direction 82, the droplet 10 is subjected to a force F2.

[Effect]

Therefore, as shown in FIG. 2 and FIG. It can be transferred to the base material 2 side.

This stabilizes the arc, suppresses spatter, forms beautiful beads, and allows high-quality welding.

[Embodiments of the invention]

The present invention will be explained in detail below.

Example: In the welding machine shown in FIG.
Using #I mild steel welding wire, argon gas containing 1% 02, an alternating magnetic field of 100 Hz was applied, welding was performed at various welding currents, and the transfer of droplets was photographed with a high-speed camera.
The droplet size and sputtering rate were measured. The results are shown in FIGS. 4' and 5. The sputtering rate is (superimposed spatter) / (consumed welding wire weight) x 100 (%)
). El in FIG. 4 is the characteristic line of this example,
C1 is a characteristic line of the conventional method in which no alternating magnetic field is applied.

B2 in FIG. 5 is a characteristic line of this embodiment, and C2 is a characteristic line of the conventional method in which no alternating magnetic field is applied. From Figure 4, 1 for mild steel
．． It can be seen that when the welding wire in No. 6- is used, fine droplets can be transferred even at a welding current of 100 A or less by applying an alternating magnetic field.

Also, from Fig. 5, it can be seen that by applying an alternating magnetic field, the conventional MU
It can be seen that the spatter rate can be significantly reduced compared to the G welding method.

Next, the influence of the alternating magnetic field frequency (f) on the sputtering rate was investigated, and the characteristic diagram shown in FIG. 6 was obtained. In addition, A in Fig. 6 indicates a welding current of 100 amperes, and B indicates a welding current of 20 amperes.
This is the case of 0 ampere. From this figure 6, 40 to 20
It can be seen that using an alternating magnetic field frequency of 0H7 is effective in reducing the sputtering rate.

(Effect of R light) As detailed above, according to the present invention, in the low current range,
By moving the droplets generated at the tip of the welding wire and transferring them to the base metal before they grow into large particles, the arc is stabilized, spatter is suppressed, and beautiful beads are created. It is possible to provide a MIG welding method that enables formation of the wafer and performs high-quality welding.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing one form of welding welding fluid used in the MIG welding method of the present invention, and FIGS. 2 and 3 are MIG welding methods of the present invention.
A schematic diagram to explain G welding. Figure 4 is a characteristic diagram showing the relationship between welding current and droplet deposition when an alternating magnetic field is applied and when it is not applied. Figure 5 is a diagram showing the relationship between welding current and droplet deposition when an alternating magnetic field is applied. FIG. 6 is a characteristic diagram showing the relationship between alternating frequency and sputtering rate under the condition that the welding current is 100.200 amperes, Figure 7 shows the conventional MIG
A schematic diagram of the welding machine used for welding, Figure 8 is for MIGI connection! FIG. 2 is an explanatory diagram showing a pulse arc welding method for over-welding in a region. 2... Base metal, 3... Welding/welding arc, 4... Welding wire, 6... Shielding gas, 8... Wire feeding roller, 9... DC welding power source, 10...・Droplet, 11...
・Magnetic material, 12... Excitation coil, 13... Alternating current generation power supply. Applicant's representative Patent attorney Takehiko Suzue Fig. 1 Fig. 2 Fig. 3 Fig. 4 (Welding light cut) Sentence) ' (Hz) 7th
Figure 8

Claims (1)

[Claims] By applying an alternating magnetic field to the tip of the welding wire in a direction perpendicular to the wire feeding direction and vibrating the droplets generated at the wire tip, the droplets can be transferred to the base metal before they become large. A MIG welding method characterized by: