A narrow gap laser-GMAW hybrid welding method with molten pool coupling

Abstract

The present invention relates to a narrow gap laser-GMAW composite welding method coupled with a molten pool, and belongs to the field of welding technology. The technical scheme is as follows: during welding, the spot of the laser beam (1) swings along a predetermined trajectory inside the narrow gap groove, melts the side wall of the narrow gap groove, and forms a laser molten pool (3); the GMAW arc (2) remains stationary at the center position of the narrow gap groove, directly acts on the laser molten pool (3), and the GMAW arc (2) forms a liquid metal that spreads and flows along the surface of the laser molten pool (3) under the action of surface tension, and after coupling with the laser molten pool (3), a composite molten pool (4) is formed, which is finally cooled and solidified into a weld (5). The present invention ensures that the side wall of the narrow gap groove is well fused. Since the GMAW arc and welding wire do not perform periodic reciprocating motion during the welding process, the wear of the conductive nozzle is significantly reduced. In particular, for materials such as high-strength steel, stainless steel and titanium alloy, the welding stability and reliability are significantly improved during long-term welding.

Description

Technical Field

[0001] The invention relates to a molten pool coupled narrow gap laser-GMAW composite welding method, belonging to the technical field of welding. Background Art

[0002] The groove size and groove cross-sectional area of ​​the narrow gap gas metal arc welding (NG-GMAW) method are significantly smaller than those of conventional welding methods. It has the characteristics of high welding production efficiency, low economic cost, and good welding quality. It is increasingly used in the manufacture of medium and thick plates and thick plate structures in industries such as shipbuilding, nuclear power, pressure vessels, and engineering machinery. One of the most critical technologies in the narrow gap gas metal arc welding process is to solve the problem of side wall fusion. Currently, the commonly used methods are precise arrangement of welding wires, mechanical swing of the arc, and bending of welding wires. These methods are essentially to drive the arc to periodically point to the two side walls of the narrow gap groove to solve the problem of poor fusion on both sides. When solving the side wall fusion problem in the above method, on the one hand, the performance requirements of the narrow gap welding gun are extremely strict because the welding wire or the conductive nozzle needs to be accurately moved or arranged in the groove, especially when welding high-strength steel, titanium alloy and other materials. When the welding wire swings for a long time, it will seriously wear the conductive nozzle, thereby affecting the stability and reliability of the welding quality; on the other hand, because the arc swings in the groove and the two side walls need to be melted by arc heating, the welding speed cannot be too fast, which limits the further improvement of the narrow gap welding efficiency.

[0003] In order to solve the above problems, it is generally expected that the arc will only be deflected periodically without mechanical reciprocating motion of the welding wire or the conductive nozzle, and the arc energy will be applied to the side wall of the narrow gap parent metal to solve the problem of non-fusion of the side wall. At present, there are mainly two ways. The first way is to drive the arc to deflect periodically by applying a transverse alternating magnetic field. CN202111000648.5, named "A double-wire heterogeneous or homogeneous metal magnetically controlled swinging arc GTAW narrow gap welding device and method" adopts this method. Another way is to use a galvanometer-swinging laser beam to induce arc periodic deflection. CN201810577074.X, named "Large thick plate narrow gap vibration laser-arc composite welding method and welding device", CN202010923158.1, named "A swinging laser-induced consumable gas shielded welding arc ultra-narrow gap welding process method" and so on all adopt this method. These methods have improved welding stability and efficiency compared to conventional narrow gap welding methods. However, using only an external magnetic field or laser beam swing to drive the arc to passively deflect will affect the arc shape and the stability of the molten pool. Especially when using a laser beam, the laser keyhole will also interact with the arc molten pool, which can easily form defects such as pores and poor forming, thus affecting the quality of the welded joint. In addition, whether it is a magnetic field or a laser beam that induces arc movement, the essence of solving the side wall fusion is still to heat and melt the side wall of the parent material through periodic arc deflection. At this time, compared with the laser beam, the arc energy density is lower and the time to melt the side wall is longer, which limits the further improvement of the welding speed. Summary of the invention

[0004] The purpose of the present invention is to provide a narrow gap laser-GMAW hybrid welding method coupled with a molten pool, in which the laser beam swings in the narrow gap groove to melt the groove side wall, the GMAW arc does not swing, and the formed liquid metal is coupled with the laser molten pool to finally form a weld. The welding efficiency is high, and the weld quality is stable and reliable during long-term welding operations, thereby solving the technical problems existing in the background technology.

[0005] The technical solution of the present invention is:

[0006] A molten pool coupled narrow gap laser-GMAW hybrid welding method is provided, wherein a laser beam and a GMAW arc are sequentially arranged in the narrow gap groove of the workpiece to be welded along the welding direction; the energy density of the laser beam spot on the weld surface is 3.0×10 5 W / cm 2 -5×10 6 W / cm 2During welding, the spot of the laser beam swings along a predetermined trajectory inside the narrow gap groove, melting the side wall of the narrow gap groove and forming a laser molten pool; the GMAW arc remains stationary at the center of the narrow gap groove and acts directly on the laser molten pool. The liquid metal formed by the GMAW arc spreads and flows along the surface of the laser molten pool under the action of surface tension, and after coupling with the laser molten pool, a composite molten pool is formed, which is finally cooled and solidified into a weld.

[0007] Furthermore, the predetermined trajectory of the laser beam spot inside the narrow gap groove is the laser beam spot trajectory, the laser beam spot trajectory is an arbitrary shape, the trajectory width D3=W3+(1mm-4mm) of the laser beam spot on the weld surface perpendicular to the welding direction, W3 is the weld surface width, the trajectory width D2 of the laser beam spot on the weld surface along the welding direction is 3mm-10mm, and the oscillation frequency of the laser beam is 30 Hz-300Hz.

[0008] Furthermore, the angle α between the laser beam and the center line of the GMAW arc is 10°-60°, the angle β between the laser beam and the vertical direction is 0°-30°, the distance between the center of the laser beam trajectory and the center of the GMAW arc on the weld surface is the filament spacing D1, and the filament spacing D1 is 5mm-30mm.

[0009] Furthermore, the power of the laser beam is 1kW-10kW, the spot diameter of the laser beam on the weld surface is 0.2mm-1mm; the current of the GMAW arc is 120A-400A, the welding wire diameter is 0.8mm-1.6mm, the shielding gas flow rate is 20L / min-80L / min; and the welding speed is 100mm / min-1500mm / min.

[0010] Furthermore, the thickness of the workpiece to be welded is 8 mm-300 mm, the groove root width W1 of the narrow gap groove is 6 mm-12 mm, and the groove surface width W2 of the narrow gap groove is 10 mm-14 mm.

[0011] The positive effects of the present invention are as follows: During the welding process, an oscillating laser beam is used to melt the side wall of the groove and form a laser molten pool. The GMAW arc does not oscillate, and the formed liquid metal spreads and flows along the laser molten pool under the action of surface tension, ensuring that the side wall of the narrow gap groove is well fused. Since the GMAW arc and welding wire do not perform periodic reciprocating motion during the welding process, the wear of the conductive nozzle is significantly reduced, especially for materials such as high-strength steel, stainless steel and titanium alloy, the stability and reliability of welding are significantly improved during long-term welding. In addition, since the arc does not oscillate during the welding process, it is more suitable to increase the welding speed, thereby improving the welding production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a front view of the principle of the present invention;

[0013] Figure 2 It is a top view of the principle of the present invention;

[0014] Figure 3 It is a side view of the principle of the present invention;

[0015] Figure 4 This is a macroscopic photograph of the cross section of the first layer of weld in Example 1 of the present invention;

[0016] Figure 5 This is a macroscopic photograph of the cross section of the first layer of weld in Example 2 of the present invention;

[0017] Figure 6 This is a macroscopic photograph of the cross section of the first layer of weld in Example 3 of the present invention;

[0018] Figure 7 This is a macroscopic photograph of the cross section of the first layer of weld in Example 4 of the present invention;

[0019] Figure 8 This is a macroscopic photograph of the cross section of the weld in Example 5 of the present invention;

[0020] In the figure: 1 laser beam, 2 GMAW (gas metal arc welding) arc, 3 laser molten pool, 4 composite molten pool, 5 weld seam, 6 laser beam spot trajectory. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0022] See attached Figure 1-3 , this embodiment provides a molten pool coupled narrow gap laser-GMAW hybrid welding method, wherein a laser beam 1 and a GMAW arc 2 are sequentially arranged in the narrow gap groove of the workpiece to be welded along the welding direction; the energy density of the laser beam 1 on the spot on the weld surface is 3.0×10 5 W / cm 2 -5×10 6 W / cm 2 During welding, the spot of the laser beam 1 swings along a predetermined trajectory inside the narrow gap groove, melts the side wall of the narrow gap groove, and forms a laser molten pool 3; the GMAW arc 2 remains stationary at the center position of the narrow gap groove, directly acting on the laser molten pool 3, and the liquid metal formed by the GMAW arc 2 spreads and flows along the surface of the laser molten pool 3 under the action of surface tension, and after coupling with the laser molten pool 3, a composite molten pool 4 is formed, which is finally cooled and solidified into a weld 5.

[0023] In this embodiment: D1 is the filament spacing (the distance between the center of the laser beam trajectory and the center of the GMAW arc on the weld surface), D2 is the trajectory width of the laser beam spot on the weld surface along the welding direction, D3 is the trajectory width of the laser beam spot on the weld surface perpendicular to the welding direction, W1 is the groove root width, W2 is the groove surface width, W3 is the weld surface width, α is the angle between the laser beam and the center line of the GMAW arc, and β is the angle between the laser beam and the vertical direction.

[0024] See attached Figure 2 The predetermined trajectory of the spot of the laser beam 1 inside the narrow gap groove is the laser beam spot trajectory 6, and the laser beam spot trajectory 6 is of any shape. The trajectory width D3=W3+(1mm-4mm) of the spot of the laser beam 1 on the weld surface perpendicular to the welding direction, W3 is the weld surface width, the trajectory width D2 of the spot of the laser beam 1 on the weld surface along the welding direction is 3mm-10mm, and the oscillation frequency of the laser beam 1 is 30 Hz-300Hz.

[0025] See attached Figure 3 The angle α between the center line of the laser beam 1 and the GMAW arc 2 is 10°-60°, the angle β between the laser beam 1 and the vertical direction is 0°-30°, the distance between the trajectory center of the laser beam 1 and the center of the GMAW arc 2 on the weld surface is the filament spacing D1, and the filament spacing D1 is 5mm-30mm.

[0026] Preferably, the power of the laser beam 1 is 1kW-10kW, and the spot diameter of the laser beam 1 on the weld surface is 0.2mm-1mm; the current of the GMAW arc 2 is 120A-400A, the welding wire diameter is 0.8mm-1.6mm, the shielding gas flow rate is 20L / min-80L / min; and the welding speed is 100mm / min-1500mm / min.

[0027] Preferably, the thickness of the workpiece to be welded is 8 mm-300 mm, the groove root width W1 of the narrow gap groove is 6 mm-12 mm, and the groove surface width W2 of the narrow gap groove is 10 mm-14 mm.

[0028] See attached Figure 4 , Embodiment 1:

[0029] The thickness of the workpiece to be welded is 50 mm, the groove root width W1 is 8 mm, and the groove surface width W2 is 10 mm;

[0030] The spot of laser beam 1 swings along an elliptical trajectory inside the narrow gap groove. During the first welding, the track width D3 of the spot of laser beam 1 on the weld surface perpendicular to the welding direction is 10 mm. When welding other welds, the width of D3 is determined according to the surface width W3 of the previous weld, specifically D3=W3+2 mm. The track width D2 of the spot of laser beam 1 on the weld surface along the welding direction is 5 mm, and the laser swing frequency is 250 Hz.

[0031] The angle α between the center line of the laser beam 1 and the GMAW arc 2 is 30°, the angle β between the laser beam 1 and the vertical direction is 0°, and the filament spacing D1 (the distance between the center of the trajectory of the laser beam 1 and the center of the GMAW arc 2 on the weld surface) is 10 mm.

[0032] Preferably, the power of the laser beam 1 is 3 kW, the spot diameter of the laser beam 1 on the weld surface is 0.4 mm; the current of the GMAW arc 2 is 240 A, the welding wire diameter is 1.2 mm, the shielding gas flow rate is 35 L / min; and the welding speed is 500 mm / min.

[0033] The first layer of welding effect is as follows Figure 4 As shown, it can be seen that the side wall of weld 5 is well fused, and no welding defects such as pores, cracks, and slag inclusions occur.

[0034] See attached Figure 5 , Embodiment 2:

[0035] The thickness of the workpiece to be welded is 50 mm, the groove root width W1 is 10 mm, and the groove surface width W2 is 14 mm;

[0036] The spot of the laser beam 1 swings along an ∞-shaped trajectory inside the narrow gap groove. During the first welding, the track width D3 of the spot of the laser beam 1 on the weld surface perpendicular to the welding direction is 12 mm, and other parameters are consistent with those in Example 1.

[0037] The first layer of welding effect is as follows Figure 5 As shown, the side wall of weld 5 is well fused, and no welding defects such as pores, cracks, and slag inclusions occur.

[0038] See attached Figure 6 , Embodiment 3:

[0039] The thickness of the workpiece to be welded is 50 mm, the groove root width W1 is 11 mm, and the groove surface width W2 is 14 mm;

[0040] The spot of laser beam 1 oscillates along a circular trajectory inside the narrow gap groove. When welding the first pass, the diameter of the circular trajectory is 13 mm. When welding other welds, the width D3 is determined according to the surface width W3 of the previous weld, specifically D3=W3+3 mm. The laser oscillation frequency is 150 Hz.

[0041] The angle α between the center line of the laser beam 1 and the GMAW arc 2 is 45°, the angle β between the laser beam 1 and the vertical direction is 10°, and the filament spacing D1 (the distance between the center of the trajectory of the laser beam 1 and the center of the GMAW arc 2 on the weld surface) is 25 mm.

[0042] Preferably, the power of the laser beam 1 is 4 kW, the spot diameter of the laser beam 1 on the weld surface is 0.6 mm; the current of the GMAW arc 2 is 320 A, the welding wire diameter is 1.2 mm, the shielding gas flow rate is 45 L / min; and the welding speed is 800 mm / min.

[0043] The first layer of welding effect is as follows Figure 6 As shown, the side wall of weld 5 is well fused, and no welding defects such as pores, cracks, and slag inclusions occur.

[0044] See attached Figure 7 , Embodiment 4:

[0045] The thickness of the workpiece to be welded is 50 mm, the groove root width W1 is 12 mm, and the groove surface width W2 is 13 mm; the filament spacing D1 (the distance between the trajectory center of the laser beam 1 and the center of the GMAW arc 2 on the weld surface) is 30 mm, the power of the laser beam 1 is 5 kW, and the other parameters are the same as those in Example 3.

[0046] The first layer of welding effect is as follows Figure 7 As shown, the side wall of weld 5 is well fused, and no welding defects such as pores, cracks, and slag inclusions occur.

[0047] See attached Figure 8 , Embodiment 5:

[0048] The thickness of the workpiece to be welded is 20 mm, the groove root width W1 is 8 mm, and the groove surface width W2 is 12 mm;

[0049] The spot of laser beam 1 swings along a circular trajectory inside the narrow gap groove. The diameter of the circular trajectory of the spot of laser beam 1 in the first layer and the filling layer is 12 mm, and the diameter of the circular trajectory of the spot of laser beam 1 in the cover layer is 13 mm. The laser swing frequency is 60 Hz.

[0050] The angle α between the laser beam 1 and the center line of the GMAW arc 2 is 45°, the angle β between the laser beam 1 and the vertical direction is 15°, and the filament spacing D1 (the distance between the center of the trajectory of the laser beam 1 and the center of the GMAW arc 2 on the weld surface) is 15 mm.

[0051] The power of laser beam 1 is 5 kW, and the spot diameter of laser beam 1 on the weld surface is 0.8 mm; the current of GMAW arc 2 is 280 A, the diameter of welding wire is 1.2 mm, the flow rate of shielding gas is 50 L / min; and the welding speed is 600 mm / min.

[0052] Welding effect Figure 8 As shown, the side wall of weld 5 is well fused, and no welding defects such as pores, cracks, and slag inclusions occur.

[0053] This technical solution uses a coupled welding method that uses a molten pool formed by a oscillating galvanometer laser beam and a molten pool formed by a GMAW arc. During the welding process, the arc does not perform periodic deflection motion. A high-energy-density laser beam is used to melt the side wall metal of the parent material, which solves the fusion problem and significantly improves the welding speed. The weld quality is stable and reliable.

Claims

1. A molten pool coupled narrow gap laser-GMAW hybrid welding method, characterized in that: Along the welding direction, a laser beam (1) and a GMAW arc (2) are sequentially arranged in the narrow gap groove of the workpiece to be welded; the energy density of the laser beam (1) on the spot on the weld surface is 3.0×10 5 W / cm 2 -5×10 6 W / cm 2 During welding, the spot of the laser beam (1) swings along a predetermined trajectory inside the narrow gap groove, melts the side wall of the narrow gap groove, and forms a laser molten pool (3); the GMAW arc (2) remains stationary at the center position of the narrow gap groove, does not swing, and directly acts on the laser molten pool (3). The GMAW arc (2) forms liquid metal that spreads and flows along the surface of the laser molten pool (3) under the action of surface tension. The formed liquid metal is coupled with the laser molten pool (3) to form a composite molten pool (4), which is finally cooled and solidified into a weld (5).

2. The molten pool coupled narrow gap laser-GMAW hybrid welding method according to claim 1, characterized in that: The predetermined trajectory of the spot of the laser beam (1) inside the narrow gap groove is the laser beam spot trajectory (6), the laser beam spot trajectory (6) is of any shape, the trajectory width D3 of the spot of the laser beam (1) on the weld surface perpendicular to the welding direction is D3=W3+(1mm-4mm), W3 is the weld surface width, the trajectory width D2 of the spot of the laser beam (1) on the weld surface along the welding direction is 3mm-10mm, and the oscillation frequency of the laser beam (1) is 30 Hz-300Hz.

3. A molten pool coupled narrow gap laser-GMAW hybrid welding method according to claim 1 or 2, characterized in that: The angle α between the center line of the laser beam (1) and the GMAW arc (2) is 10°-60°, the angle β between the laser beam (1) and the vertical direction is 0°-30°, the distance between the center of the trajectory of the laser beam (1) and the center of the GMAW arc (2) on the weld surface is the light wire spacing D1, and the light wire spacing D1 is 5 mm-30 mm.

4. A molten pool coupled narrow gap laser-GMAW hybrid welding method according to claim 1 or 2, characterized in that: The power of the laser beam (1) is 1 kW-10 kW, and the spot diameter of the laser beam (1) on the weld surface is 0.2 mm-1 mm; the current of the GMAW arc (2) is 120 A-400 A, the diameter of the welding wire is 0.8 mm-1.6 mm, the shielding gas flow rate is 20 L / min-80 L / min; and the welding speed is 100 mm / min-1500 mm / min.

5. A molten pool coupled narrow gap laser-GMAW hybrid welding method according to claim 1 or 2, characterized in that: The thickness of the workpiece to be welded is 8mm-300mm, the groove root width W1 of the narrow gap groove is 6mm-12mm, and the groove surface width W2 of the narrow gap groove is 10mm-14mm.

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