JPS6092084A - High-speed mig welding method - Google Patents

Abstract

PURPOSE:To enable weling of high quality and high efficiency by specifying the distance betwee the tip of a TIG electrode and material to be welded, and the distance between electrodes extension of center lines of which intersect on the material to be welded. CONSTITUTION:A welding torch consists of TIG of a preceding electrode and MIG of a succeeding electrode. Power is supplied from a DC power source 1 through current switching circuits 2, 2', and welding is performed by generating arcs 7, 8 between the materials 6 to be welded. The TIG electrode is a tungsten electrode 9, and the MIG electrode is a wire 10 fed continuously by a wire feeding device 4. The distance between the tip of the TIG electrode 9 and the material 6 to be welded is made 8-12mm.. The distance between electrodes extension of center lines of which intersect on the material 6 to be welded is made 4- 17mm.. Thus, influences of arc of TIG is reduced, preheating effect of the MIG arc is utilized effectively, and MIG welding is sped up.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention is a combination of MIG welding and TIG bath welding, which eliminates all weld defects caused by TIG welding at heavy speeds and achieves high quality. , High-speed MIG that makes highly efficient bathing possible
It concerns welding methods. .

[Background of the invention]

A welding method that combines the non-consumable electrode of TLG welding and the consumable electrode of MIG welding is disclosed in Japanese Patent Application No. 122841-1984 and Japanese Patent Application No. 5
No. 3-7481, which is used as a high-quality, high-efficiency general welding method due to its effects such as increasing the amount of bath coat and preventing blowholes. It is a non-consumable electrode and is used for copper welding.

Since each of these uses a non-consumable electrode to heat the consumable electrode and raise the temperature of the weld metal, the non-consumable electrode and the consumable electrode are used close to each other. Generally, TIG is used as a non-consumable electrode, and MIG is used as a consumable electrode.

In normal to IIG welding, there is a large temperature difference between the bath welding speed, the first half of the molten pool, and the sahanja, and as a result, a strong surface tension flow is generated on the molten pool surface based on the temperature difference.
The molten metal in the first half of the molten pool is transported to the rear part of this #t, 1% U) layer and completely forms a discontinuous bead called a hammer bead. In order to reduce the total temperature difference between the first half and the second half of the J molten pool, the normal temperature of the material to be welded must be pulsating. Therefore, if the leading electrode is a non-consumable electrode as in Japanese Patent Application No. 56-99844, a local normal heating effect on the trailing electrode can be obtained by the non-consumable electrode arc, and the welding speed is faster than the conventional MIG method with one dragon pole. will improve. However, to increase the welding speed of MIG, T
IG welding current must be increased.

But TIG's welding style? When the current increases, the arc force also increases in proportion to the square of the current1. Therefore, if you try to increase the TIG current to fully enhance the preheating effect, the TIG arc force will increase the total backward flow i''L of the molten steel. Since the KM is accelerated, the backward flow becomes faster and defective beads called humping and undercants are formed, so a significant improvement in welding speed cannot be expected.

Figure 1 uM I GiW! '1W style i 150A,'
This shows the relationship between the welding speed limit and 'l'l011 (flow) when stainless steel is fully welded under the condition of ri inter-electrode distance H4mm.The welding speed limit is the welding speed at which humping and undercut beads begin to occur.TIG When the current is small, the influence of the arc force is small, and the influence of the preheating effect is greater, and the welding speed limit becomes higher.However, as the TIG current increases, it decreases, and with TIG relaxation; at 400A, the preheating temperature becomes significantly higher. However, the force of the arc pressure acting on the molten metal becomes greater than that, and becomes lower than in the case of MIG alone.

[Purpose of the invention]

The present invention provides a welding method that completely suppresses the occurrence of humping beads due to the arc force of TIG, as described above, and can obtain good beads even at high speeds.

[Summary of the invention]

The gist of the present invention is that the shadow of the arc force of TIG #
The material to be welded by TIG can effectively obtain the preheating effect by the '1'' IG arc of the preceding electrode without being completely affected by the distance between the electrodes and the arc force, and can obtain an ideal temperature distribution for local normal heating. Experimentally determine the distance between T and the electrode tip, and
This is a fully realized high-speed MIG welding method with the addition of IG. Figure 2 shows the distance AL between the bathed material and the electrode tip.
and arc pressure (7). When AL is 3 mm or more, the arc pressure decreases rapidly, and when AL is 8 mm or more, AL
decreases to about 115, which is 1 mm, and beyond that the value remains constant. Also, Figure 3 shows the temperature distribution in the direction perpendicular to the welding direction when the AL is 2 m In and gmm;
In ntmO curve l1lja, the temperature immediately below the arc is high, but the spread of the temperature distribution is small.
In IMb), a wide area is heated to a high temperature.

Therefore, it is desirable that the AL be long. However, if the distance AL between the material to be welded and the tip of the '1 pole is 13 mm or more, TIG
1st and 4th cases where the arc becomes unstable and the bead appearance deteriorates.
The figure shows the relationship between the distance between electrodes and the welding speed limit. As the distance between the electrodes increases, the welding speed limit increases, and becomes approximately constant at 10 mm or more. However, it decreases at 16 mm or more. This is because as the distance increases, the normal temperature effect becomes smaller due to heat diffusion. From the above results, the distance between the electrodes should be 10 to 17 mm, and the distance between the material to be welded and the tip of the electrode should be 8 to 17 mm.
If the distance is less than 12mm, MIG welding can become commercially viable.

[Embodiments of the invention]

Next, an example in which butt welding of stainless steel was performed using the above combination will be explained. FIG. 5 is a configuration diagram of an apparatus according to an embodiment of the present invention. The welding torch is TIG for the leading electrode and M for the trailing electrode.
The IGs are supplied from the DC power supply 1 through the optical switching circuits 2.7'i, respectively, to generate an arc 7.8 between the materials 6 to be welded and perform bath welding. The TIG electrode is a tungsten electrode 9 and the MIG! The poles are wires 10 that are continuously fed by a wire feeding device 4. The control device 3 controls the welding current flowing through each electrode, and also performs control to alternately supply the welding current to 'I'IO and MIG. SaravcMIG
Issues a wire feed amount command according to the current.

The wire feeding control device 5 operates the entire wire feeding device based on this command. Although not shown, TIG and MIG
A welding torch consisting of a ridge pole moves along the bath tangent line. In addition, the welded part and the 'electrode have a structure in which they are covered with shielding gas4. A stainless steel base (SO8304) with a thickness of 3n1m was butt-welded7 using this device.7. M.I.
G wire is Y2O2 (φ1.2), distance between electrodes is H1
2mm, distance between the material to be welded and the tip of the non-consumable electrode i9n1m,
Switching frequency; 200H2, shield gas Ar, TIG
Turtle i, 390A.

When welding was performed under the conditions of MIGz flow: 150 A, a smooth weld bead with little excess buildup was obtained at a bath contact speed of 3 m/011 n, with the uranami bead facing backwards.

Even with a stainless steel plate as thick as 5 mm, MIGti
;200A, TIG'Ki;450A, 2m/m
A good bead could be obtained at high speed. In the welding of the embodiment, only the MIG4Th was moved 20 degrees #4 orders of magnitude (advance angle) from the vertical plane in the direction opposite to the welding direction, but both electrodes may be tilted.

〔Effect of the invention〕

Since the influence of the TIG arc force is small and the preheating effect of the MIG arc can be fully utilized, commercialization of MIG welding can be achieved. Therefore, bathing efficiency is significantly improved. .

[Brief explanation of drawings]

Figure 1 shows the relationship between the T 11 G welding flow and the welding speed limit in the conventional method. Figure 2 shows the relationship between the distance between the TiG electrode tip and the welded metal and the arc force. 3 is a diagram showing the temperature distribution, FIG. 4 is an IfM diagram showing the relationship between the I-electrode distance and the welding speed limit, and FIG. 5 is a block diagram of an example of a device implementing the method of the present invention. It is a diagram. 1... Welding power source, 2.2'... Current switching circuit, 3.
... Control device, 4... Wire feeding device, 5... Wire feeding control Gesten electrode (TIG), 1 (1... Wire 70 in Figure 1 between Umesaki wax and I material to be heated ritoshima ship At-shi arc) sail 3 year country electrode /'/] distance no (rh side di

Claims (1)

[Claims] 1. In a welding method that combines TIG welding and MIG bath welding in which welding current is passed alternately through each electrode, the preceding electrode is TIG, and the distance between the electrode tip of the TIG% electrode and the bathed material ? ]l-8~121 Old n, and the electrode ratio *' where the extensions of the center lines of both electrodes intersect on the bathed material is 4~
A high-speed MIG welding method characterized by a welding process of 17 mm.