KR100649053B1 - Laser-mig hybrid welding method - Google Patents

Abstract

A laser-MIG hybrid welding method that improves quality of a butt welded portion by diversely controlling variables used in welding according to various gaps of a butt joint, and improves workability by clearing an additional post-treatment process according to welding flaws is provided. In a laser-MIG hybrid welding method for welding a butt joint with a gap by a laser-MIG hybrid welding equipment having a laser unit and an MIG torch, the laser-MIG hybrid welding method comprises welding a welding wire of 1.2 mm using a welding voltage of 21 to 32 V when the gap is 1.0 mm or less. The method comprises welding a welding wire fed at a feeding rate of 10.5 m/min or less by the welding equipment with a torch height of 18 mm. The method comprises welding a welding wire fed at a feeding rate of 10.5 m/min or less at the gap of 1.0 mm or less using a welding current of 280 to 440 A.

Description

Laser-MIG hybrid welding method

1 is a schematic view showing a laser-MIV hybrid welding apparatus of the present invention.

Fig. 2 is a process chart showing the laser-MIV hybrid welding method of the present invention.

3 (a) to 3 (d) are welded evaluation diagrams when the gap between the base materials is 0.5 mm in the laser-MIX hybrid welding method of the present invention.

4 (a) to 4 (d) are evaluation diagrams of welded portions when the gap between the base materials is 1.0 mm in the laser-MIX hybrid welding method of the present invention.

5 is a view showing a bead surface and a cross-sectional shape according to the increase in the welding voltage in the laser-MIX hybrid welding method of the present invention.

6A to 6D are diagrams showing evaluation results of various weld currents and welded portions under electric bonding when the gap between the base materials is 1.5 mm in the laser-MIX hybrid welding method of the present invention.

7 is a view showing the state of the melt pool according to the reduction of the welding voltage in the laser-MIX hybrid welding method of the present invention.

8 (a) to 8 (d) are results diagrams showing the state of the welded part according to the adjustment of the torch height in the laser-MIX hybrid welding method of the present invention.

9 is a view showing a correlation between the increase in the torch height and the welding current in the laser-MIV hybrid welding method of the present invention.

10 (a) to 10 (c) show results of varying the height of the torch in the case where the gap between the base materials is 2.0 mm in the laser-MIV hybrid welding method of the present invention.

<Description of the symbols for the main parts of the drawings>

100: welding device 110: laser unit

120: torch 130: the base material

The present invention relates to a laser-MIX hybrid welding method, and more particularly, to a laser-MIX hybrid welding method for improving welding quality of a butt joint of a base material having a gap.

In general, laser-MIX hybrid welding uses a magnetic filler wire as an electrode, and has a good gap tolerance of the butt joint, and supplements the lack of melt amount with the weld wire in the joint having the large gap. In particular, by properly adjusting the components of the welding wire it is possible to secure very excellent weld characteristics, the recent research is being actively conducted.

However, in the conventional laser-MIX hybrid welding technology, welding defects such as undercuts, excessive weld glands, excessive back beads, and underfills are generated in welded welds according to various joint gaps between the base materials to be welded to butt joints. Poor appearance of the welded part, accompanied by a separate post-treatment process according to the weld defects had a problem of poor workability.

Accordingly, the present invention has been made to solve the problems of the prior art as described above, to improve the quality of the butt welded weld by controlling a variety of parameters used for welding in accordance with various gaps of the butt joint, welding defect It is an object of the present invention to provide a laser-MIX hybrid welding method in which a separate post-treatment process is solved and workability is improved.

A laser-MIX hybrid welding method of the present invention for achieving the above object is a laser-MIX hybrid welding method for welding a butt joint having a gap as a laser-MIX hybrid welding apparatus having a laser unit and a MIV torch. When the gap is 1.0 mm or less, the 1.2 mm welding wire is welded with a welding voltage of 21 to 32 kW.

Preferably, the torch height of the welding device is 18 mm, and the welding wire fed at a speed of 10.5 m / min or less is welded, and the welding current at this time is 280 to 440 A.

In the laser-MIX hybrid welding method for welding a butt joint having a gap as a laser-MIX hybrid welding apparatus having a laser unit and an MIX torch, when the gap exceeds 1.0 mm and is 1.5 mm or less, 1.2 mm is used. Is welded at a welding voltage of 28 kW or less at a torch height of 24 to 32 mm while feeding the welding wire at a speed of 10.5 to 15.8 m / min.

Further, in the laser-MIX hybrid welding method for welding a butt joint having a gap as a laser-MIX hybrid welding device having a laser unit and an MIX torch, when the gap exceeds 1.5 mm, a welding wire of 1.4 mm or more Is welded at a torch height of 32 mm or more.

Preferably, the welding wire is welded at a welding voltage of 25 kW or less while being fed at a speed of 15.6 m / min or less.

The welding speed of the welding device is welded at a speed of 1.5 to 2.0 m / min at a laser output of 8 to 12 kW.

Hereinafter, the present invention will be described in detail with reference to FIGS. 1 and 2.

1 and 2 are views showing a laser-MIX hybrid welding apparatus and a welding method used in the present invention.

First, the laser-MIV hybrid welding apparatus 100 used in the present invention is composed of a laser unit 110 and a MIV torch (hereinafter referred to as "torch") 120 as shown in FIG. And weld the butt joint in which the gap is present.

The welding apparatus 100 has a welding speed for welding at a speed of 1.5 to 2.0 m / min at a laser output of 8 to 12 kW, but when the welding speed is changed, the feeding speed of the welding wire to fill the gap must also be changed. The height of the torch 120 can be variably adjusted according to the spacing of the base material 130, but is initially fixed at a height of 18 mm.

On the other hand, in the present invention, the welding experiment to obtain a good welding quality while varying the butt gap of the base material 130 to 0 ~ 2mm, was performed, but the size of the filler metal (welding wire to be described later) in the gap of the butt gap is more than 1.5mm The welding was possible only after changing.

That is, when the space | interval of the said butt joint part is 1.5 mm or less, it welds with a 1.2 mm welding wire, and when the said space | gap exceeds 1.5 mm, it welds with the welding wire more than 1.4 mm.

In this experiment, not only the filler metal but also the welding voltage and the welding current should be adjusted according to the gap between the butt joints.

That is, when the butt joint has a gap of 1.0 mm or less, a torch fixed at a height of 18 mm while feeding a 1.2 mm welding wire at a speed of 10.5 m / min or less and a welding voltage of 21 to 32 kW and a 280 to 440 A Weld by welding current.

If the gap between the butt joints exceeds 1.0 mm and is 1.5 mm or less, the welding voltage of 1.2 mm is supplied at a welding height of 28 kV or less at a torch height of 24 to 32 mm while feeding 1.2 mm welding wire at a speed of 10.5 to 15.8 m / min. Weld

That is, in more detail, the feeding speed of the welding wire is 10.5 m / min at the gap of 1.0 mm and 15.8 m / min at the gap of 1.5 mm, except for the loss caused by the spatter. In consideration of the occurrence, the speed is increased by about 10%.

In addition, when the space | interval of the said butt joint part exceeds 1.5 mm, the welding wire of 1.4 mm or more is welded at the height of the torch 120 or more of 32 mm or more.

At this time, the feeding speed and welding voltage of the welding wire are satisfied with the feeding speed and the welding voltage when the gap between the butt joint is more than 1.0 mm and less than 1.5 mm, but more preferably the feeding speed and the feeding speed of 15.6 m / min or more and 25 kPa or less It is preferable to weld with a welding voltage.

In addition, the welding current under the two experimental conditions (1.0 mm <gap ≤ 1.5 mm, 1.5 mm <gap) is a value determined dependently by the above variables, which will be described in detail with reference to the following examples. .

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail.

3 to 10 are views showing a laser-MIV hybrid welding method and results according to the present invention.

<Example>

Conditions of welding variable commonly used in this experiment

-Thickness of base metal: 8㎜

-Change of gap: 0 ~ 2㎜

-Welding speed: Fixed at 1.5m / min at laser power 8㎾

-Torch height: 18mm fixed up to 1.0mm gap

             18 to 32 mm in gaps exceeding 1.0 mm

-Filler metal-1.2mm welding wire

-Feeding speed of welding wire-Refer to Table 1

First, if there is a gap in butt welding, the minimum amount of deposition required to fill the space of the seam is required. Therefore, the welding amount of the welding wire was calculated according to the gap size, and the corresponding welding wire feed amount and welding current value are shown in Table 1 below.

Required feed speed of welding wire (1.2mm dia.wire) Clearance size (mm) 0.5 One 1.5 2 Feed Speed of Welding Wire (m / min) 5.3 10.5 15.8 21.0 Welding current (A) 207 310 413 489

On the other hand, as can be seen from Table 1, the welding current has a close relationship with the feeding speed of the welding wire in MIV welding using a constant voltage welding power source.

The amount of welding and the welding current to be filled are determined according to the gap between the two base materials as shown in Table 1 above. Higher values are determined by the gap size.

And, the specifications of the welding apparatus used in this experiment are shown in Table 2 below. In particular, the welding speed, which determines the productivity of the process, was fixed at 1.5 m / min at 8 kW of laser power. This is determined by the laser power and the welding speed of the welding depth in the hybrid welding using high power laser. When controlling the welding speed during adaptive control of the process variable according to the gap, the laser power can be linked to increase the complexity of the process variable control. Because. Gathering, backside bead, undercut, and underfill were selected as evaluation items in the test section. The influence of process variables on the evaluation items was evaluated based on the modified ISO 13919-1 with the addition of Class B '.

Specification of welding device Focal Length 250 mm Laser head angle 90 deg. Torch angle 58 deg. Welding speed 1.5 m / min Torch distance 18 mm Distance between laser and arc 4mm Weld wire diameter 1.2 mm Shielding gas Kinds He, Ar, CO ₂ Flow rate 50ℓ / min

The evaluation result of the hybrid welding part in the case where the clearance is 0.5 mm and 1 mm is shown to FIG. 3 and FIG. Underfill and excess back beads did not appear in both 0.5mm and 1mm gaps, and the weld tailings in 0.5mm gaps were equivalent to Class C above 360A, causing excessive deposition. In case of 340A and 23Ｖ, the excessive voltage was observed because the welding voltage was lower than the proper condition. The undercut occurred when the welding voltage was relatively high and the welding current was low. The dotted line in FIG. 3 (d) indicates the boundary between Class B and Class B '.

As a result of superimposing four evaluation items of this experiment, when the butt weld member has 0.5mm gap at 8m laser power and 1.5m / min welding speed, 340A and 24mV are suitable arcs that do not cause defects in the weld. Judging by the welding condition.

Similar trends are shown in the 1.0 mm gap as shown in FIG. 4, but it is understood that an appropriate welding current value should be selected to fill the joint. That is, when the gap between 0.5mm and 1.0mm exists compared to the proper condition of BOP (Bead-on-Plate) welding and butt welding without gap, relatively high welding current is required to fill the joint and prevent undercut. Relatively low welding voltage is required. In addition, it can be seen that as the size of the gap increases, the value of the welding current, which causes excessive welding addition, also increases. If the welding gland is excessive, it is a defect that can be removed by a relatively simple process by grinding, but the undercut can be improved by grinding and re-welding. Therefore, the selection of welding conditions should be considered to prevent undercut rather than excessive welding gong. It seems to be.

3 and 4, excessive welding voltages cause undercuts in the welds, and excessive welding voltages cause beads to become convex and increase spatter, so proper welding voltage setting is important. The area under which undercut does not occur according to each gap is a part below the dotted line. An inverted triangle is a condition under which an undercut has occurred, and a circle (point) is a region where undercut has not occurred.

5 shows a bead surface and a cross-sectional shape as the welding voltage increases. As the welding voltage increased, the bead width and the extortion tended to decrease, and undercut was observed above 32Ｖ. In order to prevent undercutting, a welding voltage of a predetermined level or less is required, and as shown in FIG. 3 (d), the slope of the dotted line representing an area where no undercut occurs in the 0.5 mm gap, that is, the ratio of the welding voltage and the welding current is approximately. 0.07 or so.

In this case, by using the critical welding current value in which excessive welding addition occurs, it is possible to select an appropriate welding current and welding voltage value. Even when the gap is 1 mm, it can be seen that the welding current and the voltage conditions can be calculated in the above-described manner.

On the other hand, in Fig. 5, the bead shape difference between the case where the conditions are inappropriate and the case where the conditions are appropriate is shown at 0.5 mm gap. It can be seen that when the voltage is excessive, undercut is observed on the surface of the bead, and when the voltage is too small, the formation of convex beads is observed.

In addition, in the case where the gap is 1.5 mm, the evaluation results of the hybrid welding part under various welding currents and voltages are shown in FIG. 6. As shown in FIG. 6, under all conditions used in this experiment, the bead cross-sectional shape corresponding to Class B ′ did not appear, and most of the cases showed severe undercuts with excessive back beads, and underfill due to melting was sometimes observed.

In order to improve this, various welding currents and voltages have been varied, but failed to obtain a healthy bead cross-sectional shape corresponding to B 'of the modified ISO 13919-1.

As shown in Table 1, when the gap is 1.5 mm, a wire feeding speed of 15.8 m / min is required based on the weld wire of 1.2 mm diameter to fill the gap with the weld metal. The welding current corresponding to this is 413A, and considering the welding tail, back bead and spatter, the proper welding current is about 440A.

As shown in FIG. 6, excessive back beads and undercuts were generated in the test result of the welding current of 440A or higher, which is considered to be due to the high arc pressure caused by the welding current, which greatly affects the melting pool in the gravity direction.

Therefore, in order to induce a decrease in arc pressure, the result of gradually reducing the welding voltage from 31 kW to 23 kW is shown in FIG. 7. It was not possible to remove the excess back bead and undercut completely even though it was observed that the arc length was shortened and the melt pool was reduced as the welding voltage decreased.

Therefore, in order to secure a better gap response force, the experiment result of changing the torch height from 18mm to 32mm, which was a fixed variable up to 1mm gap, and welding the welding wire at 25kW while feeding the welding wire at a speed of 17.2m / min Is shown in FIG. 8.

In the evaluation of the bead cross section, as the torch height was increased, the excess back bead was reduced and the weld tailing was generated. At the height of the torch of 28 mm or more, a gland was observed to be visible with the naked eye, and a healthy bead shape was obtained.

In addition, it can be seen that the depression of the molten pool is significantly reduced as the height of the torch is increased even in the high speed photographing result. This is because when the torch height is increased in the GMA welding power supply in the constant voltage mode, the welding wire protrusion length increases, and thus the voltage drop occurs and the welding current value decreases, thereby reducing the arc pressure.

That is, as can be seen in Figure 8, when the torch height (CTWD: contact tip-to-workpiece distance) is large, the welding current is reduced, thereby reducing the pressure of the arc.

Therefore, although the undercut can be reduced, when it exceeds 1.0 mm, the formation of the favorable weld part without undercut is possible only when the height of a torch is controlled. The shape of the beads along the height of the torch in the 1.5 mm gap is shown in FIG. 8. That is, when the torch height is small, excessive bead generation occurs due to the arc pressure, and undercut occurs depending on the site. However, when the torch height is large, good weld formation is observed.

And, as shown in Figure 9, the welding current value decreases as the torch height increases, so that it is possible to control the arc pressure by lowering the welding current value while maintaining the welding wire feeding speed of 17.2 m / min to fill the joint. (The welding voltage at this time is 25 mA, and the welding current is determined between 320 and 400 A).

In addition, when the gap is 2 mm, the arc of the laser beam and the GMA welding wire are pulled out between the gaps, and the arc is very unstable even when the arc does not occur or the arc is generated. Did.

Therefore, when welding was performed by replacing the 1.2 mm diameter welding wire with 1.4 mm, normal welding was performed. However, as shown in the experimental results in the 1.5 mm gap, the welding current and the voltage alone did not form a healthy weld.

Accordingly, as a result of increasing the torch height to 34 mm by the same method as performed in the 1.5 mm gap as shown in FIG. 10, it was possible to prevent underfill and excessive back bead at 32 mm or more, corresponding to ISO 13919-1 Class B '. Results could be obtained.

At this time, the welding wire was welded at a welding voltage of 25 kW or less, preferably 20 kW while feeding the wire at a speed of 15.6 m / min or less.

On the other hand, the conclusion of the experiment of the present embodiment,

① In case of hybrid welding in the butt weld where the gap is less than 1mm, the welding failure is mainly caused by excessive welding and undercut.In case of the gap of 1.5mm or more, undercut, excessive back bead, and underfill are the major welding defects. It was confirmed that.

② The cause of excessive weld extinguishing and undercut in the gap of less than 1mm are the excessive transmission wire speed and welding voltage, respectively, and the ratio of welding wire supply speed and welding voltage is suggested to prevent this.

③ In the gap more than 1.5mm, it is required to increase the welding wire feeding speed to fill the joint, and the welding defects such as undercut, excessive back bead, and underfill are generated due to the increase of welding current and arc pressure. It was confirmed that these welding defects can be prevented by lowering the welding voltage and increasing the torch height to reduce the arc pressure.

④ If the gap size is 1mm or less, good bead can be secured by adjusting the welding current and voltage without controlling the torch height. If the gap size is 1.5mm, the welding current, welding voltage and Torch height control was required. In addition, it was confirmed that the use of welding wire with a diameter of 1.4 mm or more and the torch height control were simultaneously required in the 2 mm gap.

As described above, according to the laser-MIX hybrid welding method of the present invention, butt welded parts are welded by controlling various variables used for welding according to various gaps of the butt joint to eliminate welding defects that may occur during welding. Quality is improved, there is an advantage that workability is improved by eliminating a separate post-treatment process due to welding defects.

Claims (7)

In the laser-MIX hybrid welding method having a laser unit and a MIV torch, the laser-MIX hybrid welding method for welding a butt joint having a gap, When the gap is 1.0 mm or less, the 1.2 mm welding wire is welded at a welding voltage of 21 to 32 kW. The method of claim 1, And a torch height of the welding device is 18 mm, for welding welding wire fed at a speed of 10.5 m / min or less. The method of claim 2, The welding wire fed at a speed of 10.5 m / min or less in the gap of 1.0 mm or less is welded at a welding current of 280 to 440 A. In the laser-MIX hybrid welding method having a laser unit and a MIV torch, the laser-MIX hybrid welding method for welding a butt joint having a gap, In the case where the gap exceeds 1.0 mm and is 1.5 mm or less, the welding wire of 1.2 mm is fed at a welding voltage of 28 kV or less at a torch height of 24 to 32 mm while feeding the 1.2 mm welding wire at a speed of 10.5 to 15.8 m / min. Laser-MIX hybrid welding method. In the laser-MIX hybrid welding method having a laser unit and a MIV torch, the laser-MIX hybrid welding method for welding a butt joint having a gap, When the said gap exceeds 1.5 mm, the welding wire of 1.4 mm or more is welded at the torch height of 32 mm or more, The laser-MIX hybrid welding method characterized by the above-mentioned. The method of claim 5, And the welding wire is welded at a welding voltage of 25 kW or less while being fed at a speed of 15.6 m / min or less. The method according to any one of claims 1 to 6, The welding speed of the said welding apparatus is a laser-MIX hybrid welding method characterized by welding at a laser output of 8 to 12 kW at a speed of 1.5 to 2.0 m / min.

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