Welding seam structure regulation and control device and regulation and control method

Abstract

The invention relates to a welding seam structure regulation and control device and method, the welding seam structure regulation and control device comprises a laser system, an electric arc system, a control system and a laser stirring device, and the laser system comprises a laser device; the electric arc system comprises a tungsten electrode, the tungsten electrode is perpendicular to the sample, the laser device and the laser stirring device are obliquely arranged, and the laser stirring device is used for stirring the solidified molten pool, so that formation of columnar crystals is inhibited, and formation of isometric crystals is promoted. The welding seam structure adjusting device is utilized, the specific contour of a welding pool during solidification is determined by adjusting welding heat input and speed, laser is used in front of the contour to stir the welding pool in the solidification process so as to machine columnar crystals and promote formation of isometric crystals, and improvement of various properties, including the mechanical property, the corrosion resistance and the like, of a welding seam is facilitated; and meanwhile, the laser-electric arc hybrid welding can compress the TIG electric arc to improve the energy density so as to improve the production efficiency, the welding method is simple, and batch efficient production is facilitated.

Description

Technical Field

[0001] The invention relates to a flat plate butt welding technology, and in particular to a weld structure control device and a control method. Background Art

[0002] With the further demand of economic development and technological innovation, new materials, new structures and new processes are constantly being introduced. In the normal welding process, due to the existence of temperature gradient, columnar crystals grow toward the center when the molten pool cools, resulting in the problem of a large number of columnar crystals in the weld. The mechanical properties of columnar crystals are lower than those of equiaxed crystals, so the large number of columnar crystals seriously affect the mechanical properties of the weld. In order to inhibit the formation of columnar crystals and promote the formation of equiaxed crystals, magnetic field assistance, ultrasonic assistance or hammering have been used in the past to achieve the effect of crushing grains. The magnetic field and ultrasonic assistance have always acted on the entire molten pool, and the laser can act on a specific area. However, physical methods such as hammering or ultrasonic impact are basically cooled and the grain growth is basically completed during the post-welding forming, so the effect is not obvious. Summary of the invention

[0003] Purpose of the invention: The purpose of the present invention is to propose a weld microstructure control device and control method to promote the growth of equiaxed crystals, thereby improving the mechanical properties of the weld joint.

[0004] Technical solution: The present invention includes a laser system, an arc system, a control system and a laser stirring device. The laser system includes a laser; the arc system includes a tungsten electrode, which is perpendicular to the sample. The laser and the laser stirring device are arranged obliquely. The laser stirring device is used to stir the solidifying molten pool to inhibit the formation of columnar crystals and promote the formation of equiaxed crystals.

[0005] The laser light emitted by the laser device, the tungsten arc and the laser light emitted by the laser stirring device are coaxial with the welding seam.

[0006] The laser system and the laser stirring device are connected to a control system, and the control system is connected to a computer control terminal.

[0007] A side blowing protection device is arranged beside the laser, which mainly plays the role of protecting the optical mirror, and the rate of the protective gas is adjustable.

[0008] The tungsten electrode is connected to a protective gas cylinder, and the protective gas is blown out from the gas outlet of the tungsten electrode and directly sprayed onto the surface of the sample through the tungsten electrode.

[0009] A flow meter is provided on the pipeline connecting the tungsten electrode and the shielding gas cylinder to adjust the shielding gas rate.

[0010] The laser, tungsten pole and laser stirring device are fixed on the robot wrist. The laser and tungsten pole have six-axis adjustable freedom, which is convenient for adjusting the laser defocusing amount.

[0011] The flow meter, robot and side-blowing protection device are regulated by a computer control terminal.

[0012] A method for controlling weld structure, comprising the following steps:

[0013] The parent material is clamped by butt welding to ensure that there is no obvious gap between the two plates;

[0014] Perform laser focusing and adjust the tungsten electrode position;

[0015] Set the laser parameters, laser power is 1500-3000W, welding speed is 7-15mm / s, laser defocus is 0mm, welding current is 150-250A, gas flow is 10-30L / min. During welding, the laser is in front of the tungsten electrode, tilted to the surface of the test plate, the tungsten electrode is placed perpendicular to the test plate, and the action position is the middle position of the plate joint. The laser stirring device is behind the tungsten electrode and is also tilted to the surface of the test plate. The power is set at 200-800W.

[0016] Laser-arc hybrid welding is performed, and a laser is emitted to stir the solidifying molten pool during the molten pool solidification process.

[0017] Adding shielding gas during welding can protect the surface quality of the weld.

[0018] Beneficial effects: The present invention utilizes a weld structure adjustment device to determine the specific contour of the weld molten pool during solidification by adjusting the welding heat input and speed, and uses laser to stir the molten pool during the solidification process in front of the contour to achieve mechanical columnar crystals, promote the formation of equiaxed crystals, and is beneficial to the improvement of various properties of the weld, including mechanical properties, corrosion resistance, etc.; at the same time, laser-arc hybrid welding can compress the TIG arc to increase the energy density and thus improve production efficiency, and the welding method is simple and convenient for batch and efficient production; through the device for adjusting the weld structure by laser stirring the molten pool, the stirring position can be dynamically adjusted to improve the coupling efficiency of the laser, arc and stirring device, which is beneficial to the improvement of various properties of the weld. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0020] Figure 2 This is the metallographic diagram of the butt welding sample of the present invention. DETAILED DESCRIPTION

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

[0022] Example 1

[0023] like Figure 1As shown, the weld structure control device of this embodiment includes a laser system, an arc system, a control system 10 and a laser stirring device 3. The laser system and the laser stirring device 3 are connected to the control system 10, and the control system 10 is connected to the computer control terminal 4. The laser system includes a laser 1, and a side blowing protection device 7 is provided beside the laser 1 to prevent excessive welding smoke from damaging the lens, and the protective gas rate is adjustable; the arc system includes a tungsten electrode 2, which is connected to a protective gas cylinder 5, and a flow meter 6 is provided on the connecting pipeline; a vent hole is provided inside the tungsten electrode 2 for passing protective gas 8 to protect the surface welding quality during laser-arc hybrid welding, and the protective gas rate is adjustable. The protective gas 8 is blown out through a ceramic nozzle to protect the molten pool, prevent high-temperature oxidation, and improve the protection effect of the weld. The protective gas 8 is pure argon gas, and the gas flow rate is 10 to 30 L / min.

[0024] The laser emitted by the laser 1, the tungsten arc and the laser stirring device 3 are coaxial with the weld. Laser-arc hybrid welding can increase the energy density of the arc, increase the melting depth and improve the welding efficiency through the laser. The laser 1, tungsten electrode 2 and laser stirring device 3 are fixed on the robot wrist flange; the laser 1 and tungsten electrode 2 have six-axis adjustable degrees of freedom, which is convenient for adjusting the laser defocus; after determining the laser defocus, adjust the tungsten electrode 2 to a suitable position to ensure a good coupling effect. Under the action of the laser, the tungsten arc is compressed, which increases the energy density of the arc. The flow meter 6, the robot and the side blowing protection device 7 are controlled by the computer control terminal 4.

[0025] The angle between the laser 1 and the sample is 30-60°, the tungsten electrode 2 is perpendicular to the sample, and the angle between the laser emitted by the laser stirring device 3 and the sample is 30-60°. The angle between the laser 1 and the tungsten electrode 2 is adjustable, which is convenient for adjusting the matching distance and defocusing amount between the tungsten electrode tip and the laser spot; the laser stirring device 3 has the function of stirring the solidifying molten pool 9, inhibiting the formation of columnar crystals, promoting the formation of equiaxed crystals, and is beneficial to improving various performances. By adjusting the welding heat input, determining the shape and contour of the molten pool, and then adjusting the position of the laser of the control device into the molten pool, the coupling effect of each device is better.

[0026] The present invention utilizes the laser stirring of the semi-solidified molten pool after welding to destroy the characteristics of columnar crystal growth during the solidification process of the molten pool, so as to achieve the purpose of organizational regulation. This method can improve the equiaxed crystal structure in the weld. Laser-arc hybrid welding is used for butt welding, and the laser stirring device is started immediately after the welding starts to stir the molten pool that has begun to solidify. Since the shape of the welding molten pool is affected by the welding heat input and the welding speed, the laser stirring device needs to couple the corresponding line energy to ensure that the stirring position is correct and reasonable. Such regulation of the weld organization is conducive to the improvement of various properties of the weld, including mechanical properties, corrosion resistance, etc. At the same time, laser-arc hybrid welding can compress the TIG arc to increase the energy density and thus improve production efficiency, and the welding method is simple, which is convenient for batch and efficient production.

[0027] Example 2

[0028] The weld structure control method of this embodiment includes the following steps:

[0029] The first step is to use sandpaper to grind the surface of the parent material with a thickness of 1.0 to 4.0 mm, and use 5% sulfuric acid aqueous solution to pickle the surface to remove the oxide scale to obtain a metal sheet with a smooth and clean surface, and then clamp it; the parent material should be selected from materials with low protection requirements, such as carbon steel, stainless steel, aluminum alloy, etc.

[0030] The second step is to select steel, such as 2205 stainless steel, and adopt butt welding. When two plates are butt welded, the surfaces of the two plates must be smooth and flat, with no obvious gap between the plates. Both the laser and the arc act on the gap between the two plates.

[0031] The third step is to adjust the laser defocus and the distance between the laser spot and the tungsten electrode. Generally, the defocus is 0 mm, the tungsten electrode is perpendicular to the test plate, the distance between the tungsten electrode and the plate is controlled at 2 to 3 mm, and the horizontal distance between the tungsten electrode and the laser spot is controlled at 2 to 3 mm. The welding heat source acts directly on the butt joint gap.

[0032] Step 4. Set the laser power to 1500-3000W, the welding speed to 7-15mm / s, the laser defocus to 0mm, and the welding current to 150-250A. During the welding process, the laser acts on the gap of the butt joint of the plate, the tungsten electrode maintains an appropriate distance from the plate, the laser power in the laser stirring device is 200-800W, and the laser defocus is 0mm.

[0033] Step 5. After the welding machine parameters, laser welding parameters and laser stirring device parameters are set, laser welding is carried out. Side blowing starts at the beginning of welding, which mainly plays the role of protecting the optical mirror. The protective gas rate is adjustable. During the butt welding process, protective gas is added. The protective gas is blown out from the air outlet of the tungsten electrode and directly sprayed on the surface of the sample through the tungsten electrode to protect the surface quality of the weld. The protective gas is pure argon gas with a gas flow rate of 10 to 30 L / min. During the solidification process of the molten pool, a laser is emitted to stir the solidifying molten pool. The emitted light beams are multiple and evenly distributed along the solidification contour of the molten pool. The device for adjusting the weld structure by laser stirring the molten pool can dynamically adjust the stirring position, improve the coupling efficiency of the laser, arc and stirring device, and is conducive to improving the various properties of the weld.

[0034] The 2205 duplex stainless steel was tested and compared with conventional laser-arc hybrid welding and laser-arc hybrid welding with laser post-welding auxiliary device. After welding, the metallographic images of the two test plates were obtained through a series of test treatments, such as Figure 2 As shown in the figure, the metallographic structure at the same position is analyzed, and it is found that the number of columnar crystals in the sample treated after laser welding is greatly reduced, while the number of equiaxed crystals is correspondingly increased. And through tensile test comparison, it is found that the tensile strength of the sample treated by the post-weld laser auxiliary device is significantly higher than that of the sample without the auxiliary device, so the effect of the auxiliary device is significant.

Claims

1. A weld structure control device, characterized in that: The invention comprises a laser system, an arc system, a control system and a laser stirring device. The laser system comprises a laser; the arc system comprises a tungsten electrode, which is perpendicular to the sample. The laser and the laser stirring device are arranged obliquely. The laser stirring device is used to stir the solidifying molten pool, thereby inhibiting the formation of columnar crystals and promoting the formation of equiaxed crystals.

2. The weld structure control device according to claim 1, characterized in that: The laser light emitted by the laser device, the tungsten arc and the laser light emitted by the laser stirring device are coaxial with the welding seam.

3. The weld structure control device according to claim 1, characterized in that: The laser system and the laser stirring device are connected to a control system, and the control system is connected to a computer control terminal.

4. The weld structure control device according to claim 1, characterized in that: A side blowing protection device is arranged beside the laser.

5. The weld structure control device according to claim 4, characterized in that: The tungsten electrode is connected to a protective gas cylinder.

6. The weld structure control device according to claim 5, characterized in that: A flow meter is arranged on the pipeline connecting the tungsten electrode and the protective gas cylinder.

7. The weld structure control device according to claim 6, characterized in that: The laser, tungsten pole and laser stirring device are fixed on the robot wrist.

8. The weld structure control device according to claim 7, characterized in that: The flow meter, robot and side-blowing protection device are regulated by a computer control terminal.

9. A control method based on the weld structure control device according to any one of claims 1 to 8, characterized in that: The following steps are involved: The parent material is clamped by butt welding to ensure that there is no obvious gap between the two plates; Perform laser focusing and adjust the tungsten electrode position; Set the laser parameters, laser power is 1500-3000W, welding speed is 7-15mm / s, laser defocus is 0mm, welding current is 150-250A, gas flow is 10-30L / min. During welding, the laser is in front of the tungsten electrode, tilted to the surface of the test plate, the tungsten electrode is placed perpendicular to the test plate, and the action position is the middle position of the plate joint. The laser stirring device is behind the tungsten electrode and is also tilted to the surface of the test plate. The power is set at 200-800W. Laser-arc hybrid welding is performed, and laser is emitted to stir the solidifying molten pool during the molten pool solidification process.

10. The weld structure control method according to claim 9, characterized in that: Add shielding gas during welding.

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