CN103418917A - Laser and molten metal hybrid welding method for boards - Google Patents

Abstract

The invention relates to a laser and molten metal hybrid welding method for boards. The laser and molten metal hybrid welding method is characterized by comprising step one, machining a first base material (1) and a second base material (2) to form a butt joint end face and a groove face of a groove; step two, adding a metal solid with oxide film removed to a metal melting device, then, heating the added metal solid with the oxide film into molten metal under the protection of inert shielding gas; step three, spraying the molten metal into the bottom groove from the metal melting device by a spray gun (4); step four, radiating the upper surface of a workpiece perpendicularly by a laser beam (3) after the spray gun is started to spray, enabling focusing spots of the laser beam to be evenly distributed on the first base material (1) and the second base material (2), and moving the laser beam and the spray gun (4) simultaneously to finish the welding process. According to the method, the bottoms of holes are not molten completely, so that collapse and falling of welding seams due to downward flowing of a molten pool caused by steam pressure in the holes and the gravity of the molten pool in a laser penetration welding process are avoided.

Description

A method for composite welding plates with laser and molten metal

field of invention

The invention relates to a laser welding method, in particular to a method for composite welding plates with laser and molten metal.

background invention

Arc welding, electron beam welding, laser welding, etc. are usually used for flat welding joints for plates with a thickness of more than 20mm or 30mm.

When the traditional arc welding method is adopted, the welding workpiece needs to be grooved, and multi-layer and multi-pass welding is performed, the welding efficiency is low, the welder's labor intensity is high, and the deformation after welding is large, which requires subsequent machining; the electron beam welding method is adopted When the vacuum atmosphere is required, it is limited to the welding of specimens with small structures.

With the recent successful development of ultra-high-power and high-brightness lasers, it is possible to use laser single-pass welding for thick plates. Laser deep penetration welding is similar to electron beam welding, and can obtain welds with large depth-to-width ratios. However, simple laser welding (laser self-fluxing welding) large-thickness flat welding joints are prone to defects such as collapse and drop-off, "PA position fullpenetration high power laser beam welding of up to30mm thick AlMg3plates using electromagnetic weld pool support", science and technology of Welding and joining2012(17), ("Using electromagnetic molten pool auxiliary system high-power laser penetration welding horizontal position 30mm thick AlMg3 plate", "Welding and Joining Science and Technology" 2012 (17)) pointed out in the article that in the flat welding thick plate test piece An electromagnetic field is set below to generate an upward Lorentz force to overcome gravity, thereby inhibiting the molten pool from falling under the action of gravity. However, the gravity of the molten pool is only a small influencing factor on the collapse and fall of the molten pool.

Applied on December 12, 2011, the application number is "201110410448.7", and the invention patent titled "Large tank single-sided welding double-sided forming method and weld forming liner" discloses a large tank liner The welding method and liner solve the problem of single-side welding and double-side forming of large tanks, but the technical solution still has the following problems: in order to obtain better forming, a sufficiently large weld seam forming groove must be started on the liner , so that the bottom weld is very wide.

The invention patent published on October 3, 2012 with the publication number "CN102019481B" and the invention title "A high-strength hull structure steel flat butt welding welding process" discloses a flat butt welding process. It solves the welding groove, pre-weld preheating, welding temperature, welding sequence, welding specification parameters, and post-weld cold treatment process specifications for steel flat butt welding for high-strength hull structures, but the technical solution still has the following problems: it is necessary to set up V-shaped grooves have low production efficiency, and it is difficult to strictly control the interpass temperature in actual production.

The invention patent published on December 27, 1984, the publication number is "JP59-232690A", and the invention name is "welding method" discloses a welding method for circular parts. Specifically, laser welding is used on the outside, and the weld seam is melted. The depth is 2 mm from the lower surface of the test piece, and the inner side is welded by TIG arc welding, and the arc welding seam overlaps with the laser welding seam by about 1 mm. It solves the problem that the bottom of one-sided welding of circular parts is easy to bulge or lacks penetration, and needs follow-up processing. However, this technical solution still has the following problems: the heat input of arc welding is large, and the bottom of the laser weld will be heated and melted again. Produce structural changes, affect weld performance and reduce production efficiency.

The invention patent published on August 15, 1995, the publication number is "JP07-214316A", and the invention title is "one-sided automatic welding method and device" discloses a single-sided automatic welding method and device, which solves the problem of real-time welding from the back side. Obtain the shape of the bottom of the weld, and control the welding parameters through image processing feedback to obtain a stable penetration weld without collapse, but this technical solution still has the following problems: This method can only be used for thin plate welding and traditional arc welding methods, for laser welding Due to the influence of the internal flow of the molten pool and the huge self-weight of the molten pool, it is difficult to eliminate the collapse defects in real time through simple adjustment of process parameters.

Contents of the invention

The purpose of the present invention is to solve the welding defects such as subsidence and falling during the deep penetration welding forming process of the current ultra-high power laser (>15kW) self-fluxing welding of large-thickness plate (>20mm) flat welding joints.

The technical solution of the present invention is to provide a method for composite welding plates with laser and molten metal, which is characterized in that:

Step 1: processing the first base material and the second base material to form the butt joint end surface and the groove surface of the groove, and removing impurities on the upper and lower surfaces of the first base material and the second base material, the groove butt joint surface and the groove surface;

Step 2: Put the metal solid from which the oxide film has been removed into a metal melting device, and then, under the protection of an inert protective gas, heat the added metal solid from which the oxide film has been removed to become molten metal;

Step 3: The molten metal is sprayed from the metal melting device to the bottom groove through the spray gun. The angle α formed between the spray gun and the lower surface of the workpiece is 15°～60°, and the moving speed is 0.5m/min～10m/min;

Step 4: After the spray gun starts spraying, the laser beam radiates vertically on the upper surface of the workpiece, and the focused spot size of the laser beam is evenly distributed on the first base material and the second base material. The laser beam moves synchronously with the spray gun to complete the welding process.

Further, in step 3, the angle α formed between the spray gun and the lower surface of the first base material or the second base material is 15°-60°, and the moving speed is 0.5m/min-10m/min.

Further, in step 4, the front of the molten metal injected into the groove keeps a certain distance δ from the center of the laser beam (3).

Further, the distance δ is 2mm˜5mm.

Further, in step 1, the angle between the groove surface and the butt end surface of the base metal is 45 degrees.

Further, in step 3, the molten metal is sprayed from the metal melting device through the spray gun (4) to the groove at the bottom at a speed of 1 m/min to 1000 m/min.

Further, the metallic solid is a material homogeneous to the parent material.

Further, the metal solid is mainly made of the same material as the parent material, and at the same time, the mixed powder obtained by mixing the rare earth elements lanthanum and cerium at a ratio of 100:1 and subjected to high-energy ball milling for 10 hours is added to the molten molten metal.

Further, the method is suitable for flat butt welding or flat fillet welding joints of thick plates.

The beneficial effects of the present invention are:

1) In the present invention, since the bottom of the small hole is not penetrated, the welding seam collapse and drop caused by the steam pressure and the gravity of the molten pool in the laser penetration welding small hole are avoided;

2) The technical solution of the present invention avoids the overflow loss caused by the laser energy passing through the small hole in laser penetration welding, and improves the energy utilization rate of the laser by more than 25%. Therefore, in the case of obtaining the same weld penetration, it can reduce Laser power, thereby reducing costs;

3) Welding with the method of the present invention greatly reduces the assembly gap requirements of flat butt joints, and the maximum gap can reach about 2mm;

4) The laser and molten metal compound welding method provided by the present invention avoids the welding defects caused by the high temperature of the traditional arc, greatly reduces the welding defects such as deformation of the weldment, welding cracks and residual stress, and does not need follow-up machines after welding large thickness and large structural parts. processing.

5) Adopting the composite welding method of laser and molten metal provided by the present invention can precisely control the shape of thick plate weld seam, such as fusion width, reinforcement, etc., and can be extended and applied to thick plate horizontal welding, vertical welding and all-position welding, etc. In the process, the adaptability is strong.

6) During the experiment, the experimenters found that when the molten metal is ejected at a speed of 1m/min to 1000m/min, the temperature of the molten metal is most suitable for laser welding, and the welding interface is abnormally smooth, which has unexpected technical effects .

Description of drawings

Fig. 1 is the schematic diagram of the method of laser and molten metal composite welding sheet material of the present invention;

Fig. 2 is a side view of Fig. 1;

Fig. 3 is the weld seam schematic diagram of single laser beam welding;

Fig. 4 is the weld seam schematic diagram that the inventive method welds;

Fig. 5 is a schematic diagram of Embodiment 2;

Fig. 6 is the weld seam schematic diagram of embodiment two;

Fig. 7 is a schematic diagram of a molten metal injection device in the present invention;

Among them: 1-first base material, 2-second base material, 3-laser beam, 4-spray gun, 5-third base material, 6-fourth base material.

Detailed ways

The specific implementation manner of the present invention will be described in detail below in conjunction with accompanying drawings 1-6.

As shown in Figure 1, the welding workpiece is a large structural plate with a thickness of more than 20 mm, and a groove of a certain shape is started at the bottom of the base metal to form a flat butt weld, and the included angle of the groove is 90°. The laser beam is vertically incident on the upper surface of the workpiece to achieve deep penetration welding, and the molten metal of the same material as the base material is sprayed synchronously at the bottom to realize the composite welding connection of large-thickness flat butt joints between laser and molten metal.

In this embodiment, the method for composite welding plates with laser and molten metal includes the following steps:

Step 1: The end faces of the first base material 1 and the second base material 2 are respectively processed into (2.5mm~5mm)×45° chamfering to obtain a single-sided bevel, and the upper and lower sides of the first base material 1 and the second base material 2 are removed Impurities on the surface, groove butt joint surface and groove surface, these impurities include water stains, oil stains, rust and other impurities that affect the welding quality.

Step 2: Put the metal solid from which the oxide film has been removed into a metal melting device, and then heat the added metal solid from which the oxide film has been removed to melt under the protection of an inert protective gas.

Step 3: The molten metal is sprayed from the metal melting device to the bottom groove through the spray gun 4 at a speed of 1m/min to 1000m/min, the angle α formed between the spray gun and the lower surface of the workpiece is 15° to 60°, and the moving speed is 0.5 m/min～10m/min.

As shown in Fig. 2, spraying starts after a certain time after the laser irradiates the material, so as to ensure that the molten metal sprayed into the groove maintains a distance δ from the center of the laser beam 3, and in this embodiment, δ is 2 mm to 5 mm.

In this embodiment, since the bottom of the laser welding small hole is solid metal, the high-pressure steam inside the small hole will no longer impact the front edge of the small hole and the molten pool at the bottom to flow downward, but will flow backward at the bottom of the small hole.

Step 4: The laser beam 3 is irradiated vertically on the upper surface of the workpiece, and the focused spot size of the laser beam is evenly distributed on the first base material 1 and the second base material 2, and moves synchronously with the spray gun.

In this embodiment, the laser power density is greater than 10 ⁶ W/cm ² , forming a small welding hole deep into the material. The inside of the small welding hole is filled with high-pressure, high-speed metal vapor and plasma, and the laser beam is directly transmitted to the bottom of the small hole to obtain a large melting point. Deep welds.

In this embodiment, by precisely controlling the power of the laser beam 3 , accurate penetration depth of non-penetrating welding is obtained. In this technical solution, the welding speed is 0.5m/min-10m/min. The result is a high-quality connection with large-thickness flat butt welds.

Figures 3 and 4 show the weld morphology of flat butt joint workpieces of thick plates welded by different welding methods. When a single laser beam is used to perform penetration welding from the upper surface of the butt weld, although the operation is simple and the flexibility is high, the assembly gap between the first base material 1 and the second base material 2 must be strictly guaranteed during the welding process. In the process of ultra-high power laser deep penetration welding of large thickness plates, under the action of the huge steam pressure in the small hole and the gravity of the molten pool itself, the weld pool flows out of the molten pool, resulting in serious collapse and drop of the weld seam, so the weld seam is formed As shown in Figure 3.

As shown in Figure 4, when adopting the welding method proposed by the present invention to carry out composite synchronous welding of laser and molten metal from the upper surface and the lower surface of the flat butt weld, the groove at the bottom of the weld is filled with spray gun 4 sprayed into the groove at the bottom The liquid molten metal avoids the pressure of the high-pressure steam in the small hole to drive the molten metal downward, causing the weld to collapse and drop.

In the technical solution of the present invention, the molten metal solid can be the base material for welding. Preferably, the mixed powder obtained by mixing the rare earth element lanthanum and cerium at a ratio of 100:1 and processing it for 10 hours by high-energy ball milling is added to the molten In the molten metal, the surface tension energy at the interface between the molten metal and the air can be significantly improved, so as to obtain excellent weld bottom formation. Experiments show that this method can achieve good results for base materials with low surface tension, such as aluminum alloys and magnesium alloys. Unexpected technical effects.

Specific implementation mode 2:

Another embodiment of the present invention will be described in detail with reference to accompanying drawings 5-6.

As shown in Figure 5, the welding workpiece is a large structural plate with a thickness of more than 20 mm, forming a fillet weld, and the angle between the groove at the bottom of the horizontal test piece is 45°. The laser beam is vertically incident on the upper surface of the workpiece to realize deep penetration welding, and the molten metal of the same material as the base metal is sprayed synchronously at the bottom to realize the composite welding connection of large-thickness square angle joints between laser and molten metal.

In this embodiment, the method for composite welding plates with laser and molten metal includes the following steps:

Step 1: The end face of the fourth base material 6 is processed into (2 mm ~ 5 mm) × 45° chamfering to obtain a single-sided bevel, and impurities on the upper and lower surfaces of the fourth base material 6, the butt joint surface of the bevel and the bevel surface are removed; Impurities on the side surface and upper end surface of the third base material 5 include water stains, oil stains, rust and other impurities that affect the welding quality.

Step 2: Put the metal solid from which the oxide film has been removed into a metal melting device, and then heat the added metal solid from which the oxide film has been removed to melt under the protection of an inert protective gas.

Step 3: The molten metal is sprayed from the metal melting device through the spray gun 4 into the groove at the bottom at a speed of 1 m/min to 1000 m/min, and the angle α formed between the spray gun and the lower surface of the fourth base material 6 is 15° to 60°, The angle β formed with the side surface of the third base material 5 is 15°-45°, and the moving speed is 0.5m/min-10m/min.

Same as Embodiment 1 (Fig. 2), the spraying starts after a certain time after the laser irradiates the material, so as to ensure that the front edge of the molten metal sprayed into the groove maintains a distance δ from the center of the laser beam 3. In this embodiment, δ is 2mm~ 5mm.

The remaining steps are the same as those in Embodiment 1.

The resulting weld shape is shown in Figure 6.

As shown in Figure 7, in this technical scheme, the molten metal is extruded from the nozzle (diameter 0.5mm-2mm) through the inert gas of appropriate pressure (pressure 1bar-3bar) into the column of molten metal, and at the same time three holes sprayed around the three The column of high-pressure inert gas (pressure 3bar-5bar) converges at the central point, accelerating and pushing the column of molten metal to spray to the groove position. Under the control of high pressure and nozzle direction, the molten metal can be sprayed to the base material from any angle.

In addition, it can be seen from Figure 2 that the three columns of high-pressure gas converge first and then diverge, and the length d1 of stable convergence is relatively small, so the distance d between the spray gun and the bevel should be limited to 10mm-30mm.

Although the present invention has been disclosed in detail with reference to the accompanying drawings, it should be understood that these descriptions are illustrative only and are not intended to limit the application of the present invention. The protection scope of the present invention is defined by the appended claims, and may include various changes, modifications and equivalent solutions for the invention without departing from the protection scope and spirit of the present invention.

Claims (9)

1. the method for a laser and motlten metal composite welding sheet material is characterized in that:

Step 1: the first mother metal (1) and the second mother metal (2) are processed to form docking end face and the groove face of groove, remove impurity on the first mother metal (1) and the second mother metal (2) upper and lower surface, groove interface and groove face;

Step 2: the metal solid that will remove oxide-film is packed in the metal melting device, and then, under the inert protective gas protection, the metal solid of removing oxide-film that will add is heated as molten metal bath;

Step 3: molten metal bath is ejected in the groove of bottom through spray gun (4) from the metal melting device, and spray gun and workpiece lower surface angulation α are 15 °～60 °, and translational speed is 0.5m/min～10m/min;

Step 4: after spray gun starts injection, laser beam (3) vertical radiation workpiece surface, laser beam focal beam spot size is evenly distributed in the first mother metal (1) and the second mother metal (2) is upper, and laser beam (3) and spray gun (4) synchronizing moving, complete welding process.

2. the method for laser according to claim 1 and motlten metal composite welding sheet material, it is characterized in that: in step 3, spray gun (4) is 15 °～60 ° with the first mother metal (1) or the second mother metal (2) lower surface angulation α, and translational speed is 0.5m/min～10m/min.

3. the method for laser according to claim 1 and motlten metal composite welding sheet material, is characterized in that: in step 4, be ejected into motlten metal forward position and laser beam (3) center maintenance certain distance δ in groove.

4. the method for laser according to claim 3 and motlten metal composite welding sheet material, is characterized in that: apart from δ, be 2mm～5mm.

5. the method for laser according to claim 1 and motlten metal composite welding sheet material, it is characterized in that: in step 1, groove face docks end face angle with mother metal is 45 degree.

6. the method for laser according to claim 1 and motlten metal composite welding sheet material is characterized in that: in step 3, molten metal bath be take speed and is ejected into the bottom groove through spray gun (4) as 1m/min～1000m/min from the metal melting device.

7. the method for laser according to claim 1 and motlten metal composite welding sheet material is characterized in that: metal solid is the material with the mother metal homogeneity.

8. the method for laser according to claim 1 and motlten metal composite welding sheet material, it is characterized in that: metal solid be take the mother metal homogeneous material as main, rare-earth elements of lanthanum and cerium are mixed to the mixed-powder obtained simultaneously with 100:1 after high-energy ball milling is processed 10 hours, add in the molten metal bath after melting.

9. the method for laser according to claim 1 and motlten metal composite welding sheet material, it is characterized in that: the method is applicable to the flat butt welding of slab or the straight angle connects plumb joint.

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