Laser-electric arc hybrid welding system and welding method for dissimilar materials

Abstract

The invention discloses a laser-arc hybrid welding system and method for dissimilar materials, and belongs to the technical field of welding. The hybrid welding system comprises a material pretreatment module (1), a laser module (2), a double-arc module (3), a blowing module (4), a weld joint monitoring module (5) and a postweld treatment module (7). The welding method comprises the steps of conducting welding pretreatment on the dissimilar material to be machined, adjusting the laser output head and the electric arc welding gun on the material to be welded, setting welding parameters, conducting welding, blowing, cooling and the like. The laser-arc hybrid welding system and method for the dissimilar materials, provided by the invention, integrates pre-welding treatment, the welding process and post-welding treatment into a whole set of complete system, is easy to implement, high in automation degree and high in operability, and greatly improves the welding efficiency and the welding quality.

Description

Technical Field

[0001] The invention belongs to the technical field of welding, and in particular relates to a laser arc hybrid welding system and a welding method for dissimilar materials. Background Art

[0002] The welding of dissimilar materials combines the advantages of different materials and makes up for the disadvantages of the materials. It is widely used in large components such as rail train bogies, steam turbines, ships, and side beam boxes for aerospace. It is an important and indispensable process in the fields of engineering machinery, pressure vessels, petrochemical pipelines, energy and electricity, rail transportation, automobiles, ships, aerospace, etc. However, during the welding of dissimilar materials, the instability of the weld pool and keyhole caused by the power, the violent metal evaporation and splashing caused by the liquefaction and gasification of the materials, and the uneven distribution of the welding pool temperature and fluid dynamics lead to uneven and insufficient mixing of the welding interface materials, making the welded structure unstable. In addition, due to the difference in material properties, weld segregation is prone to occur during the welding process, resulting in welding defects such as dents, cracks, lack of fusion, and pores, which seriously affect the comprehensive performance of the welded workpiece, fail to meet the needs of industrial production, and affect industrial development.

[0003] At present, laser arc hybrid welding technology is widely used in the field of welding, especially for the welding of dissimilar materials and the welding of materials with complex structures. Laser arc hybrid welding technology not only combines the advantages of laser and arc, but also makes up for their respective shortcomings. It has the advantages of high cladding, high penetration, low heat input, low deformation, good weld quality, high welding efficiency, easy automation, etc., and can be composed of various composite forms according to different relative positions, heat source combinations, energy matching, etc. For the welding of two materials with large differences in composition, the arc wire will lead to uneven weld materials no matter which material it is biased towards, which requires a new composite form based on material matching. In addition, due to the high energy density of laser arc hybrid welding, the deviation between the workpiece temperature and the ambient temperature after welding is too large, and the cooling speed is fast, resulting in serious deformation of the workpiece and weakened interface strength. If the post-weld heat treatment method is adopted, secondary heating may also affect the quality of the welding interface.

[0004] In summary, the existing laser arc hybrid welding systems and methods have some defects and need further improvement. Summary of the invention

[0005] In order to solve the welding quality problems of uneven and loose materials, uneven welds, fast cooling speed after welding, severe thermal deformation and other welding joints of dissimilar materials, the present invention proposes a dissimilar material laser arc hybrid welding system and welding method, which performs complex surface pretreatment on the materials, improves the metallurgical bonding ability between dissimilar material plates, improves the strength of the welding interface, performs post-weld treatment on the welding workpiece, slows down the cooling speed, eliminates stress and deformation, increases plasticity and toughness, and achieves high-quality connection.

[0006] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0007] A laser arc hybrid welding system for dissimilar materials, comprising a material pretreatment module 1, a laser module 2, a dual arc module 3, an air blowing module 4, a weld monitoring module 5, and a post-weld processing module 7; the material pretreatment module 1 is composed of a cutting machine; the laser module 2 comprises a laser main box 20 and a laser output head 21, the laser output head 21 is movable relative to the gap and emits a laser beam at an angle of 45° acting on the gap between two material clamping plates; the dual arc module 3 comprises a first arc welding machine 30, a first arc welding gun 31, a second The arc welding gun 32, the second arc welding machine 33 and the welding machine controller 34; the air blowing module 4 includes three inert gas storage devices 40; the weld monitoring module 5 includes an industrial high-definition camera 50 and a computer 51, which are used to monitor the convexity and concavity of the weld in real time, and feed back the results to the laser main box 20 and the welding machine controller 34 through the computer 51; the post-weld processing module 7 is composed of a heat preservation device made of silicon carbide high-temperature resistant material, which is used to slow down the cooling rate of the workpiece after welding, eliminate stress and deformation, and increase plasticity and toughness;

[0008] The laser mainframe box 20 is connected to a computer 51 via an optical fiber, and laser parameters are controlled by the computer 51. The laser mainframe box 20 is also connected to a laser output head 21.

[0009] The three inert gas storage devices 40 provide protective gas to the laser and arc devices. The blown gas covers the arc and the molten pool, protecting the arc and the molten pool from the influence of oxygen and nitrogen in the air, preventing oxidation and nitridation, and reducing spatter generation. It blows away the residues in the laser welding process and improves the mechanical properties and corrosion resistance of the weld.

[0010] Preferably, the welding machine controller 34 is a Huandian IDP300 welding controller, which adjusts the current and voltage through the control circuit to control the temperature of the welding zone and the formation of the molten pool, and controls the cooling and solidification process of the molten pool by setting the welding time.

[0011] A laser arc hybrid welding method for dissimilar materials comprises the following steps:

[0012] Step 1: Perform welding pretreatment on the dissimilar materials to be processed, and process rectangular grooves on the surface of the dissimilar materials to be processed, with a groove width and depth of 1 cm and a groove interval of 1 cm, wherein the first groove of the first material 60 starts from the left 1 cm position and is opened at an interval of 1 cm; the first groove of the second material 61 starts from the left edge position and is opened at an interval of 1 cm;

[0013] Step 2: Cross-fasten the first material 60 and the second material 61 in an L-shape and fix them on the welding platform with a clamp;

[0014] Step 3: Adjust the position of the laser output head 21 so that the angles between the emitted laser beam and the first material 60 and the second material 61 are both 45 degrees, and adjust the first arc welding gun 31 and the second arc welding gun 32 to be placed on both sides of the laser output head 21 one after the other along the gap direction, forming an angle of 20 to 45 degrees with the laser beam;

[0015] Step 4: Set the output power and duty cycle parameters of the laser through the computer 51, make the laser mainframe 20 output the laser, set the current and voltage parameters of the arc through the welding machine controller 34, and then start the laser and the two arcs at the same time, and the laser output head, the first arc welding gun 31 and the second arc welding gun 32 move in the direction of the gap extension at the same speed, and monitor the convexity and concavity of the weld in real time through the weld monitoring module 5, and feed back the results to the laser mainframe 20 and the welding machine controller 34 through the computer 51, so that the laser and arc parameters can be increased or decreased at any time according to the results;

[0016] While carrying out step 4, the blowing module 4 is turned on to deliver inert gas to the welding area to blow away the slag splashed during the welding process;

[0017] Step 5: Immediately after welding is completed, the welded workpiece is placed in the silicon carbide high temperature resistant insulation device of the post-weld processing module 7 by a robot, and set to cool to room temperature for ten hours to slow down the cooling speed, eliminate stress and deformation, and improve the strength of the welding interface.

[0018] The beneficial effects of the technical solution provided by the present invention are:

[0019] 1. The present invention performs surface pretreatment on dissimilar materials, forms the welding sides of the materials into complementary serrated structures, and splices them in an L shape, utilizing the effect of the mortise and tenon structure to make the welding stronger and the material ratio at the welding point more uniform.

[0020] 2. The present invention adds a double arc module 3 to place the first arc welding gun 31 and the second arc welding gun 32 on both sides of the laser output head 21, one in front and one in the back, along the gap direction, and play the role of arc guidance and laser guidance at the same time. When the arc is in front and the laser is in the back during the laser arc hybrid welding process, the arc will expand the range of heat action, improve the welding bridging ability, and reduce the assembly accuracy requirements for the gap of the welded parts; when the laser is in front and the arc is in the back, the laser will push the molten pool to flow backward, but the middle part of the molten pool will be squeezed, causing the height of the molten pool to change continuously, promoting the generation of short-circuit transition, and the number of spatters will increase. The arc in the back can effectively alleviate the fluctuation of the molten pool, and can realize a complete droplet transition process and reduce the number of spatters. In addition, the double arc can transmit welding wires corresponding to two dissimilar materials with large differences in composition, so that the material distribution at the weld is more uniform and the strength of the weld interface is enhanced. In addition, by using the first arc welder 30 and the second arc welder 33 in conjunction with the welding machine controller 34, the automation, accuracy and work efficiency of the welding process can be significantly improved.

[0021] 3. The present invention monitors the convexity and concavity of the weld in real time through the weld monitoring module 5, and derives an evaluation threshold based on the Pythagorean theorem, which can automatically judge whether the weld is convex or concave, and adjust the laser parameters and arc parameters in real time according to the judgment results to achieve excellent weld morphology and high-quality welding.

[0022] 4. The present invention immediately places the welded workpiece in a silicon carbide high-temperature resistant insulation device through the post-weld processing module 7, which can slow down the cooling rate of the workpiece after welding, avoid stress deformation caused by too fast cooling rate, increase plasticity and toughness; and also avoid the influence of secondary heating of post-weld heat treatment on the interface quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the overall structural block diagram of the present invention.

[0024] Figure 2 It is the overall connection diagram of the present invention.

[0025] Figure 3 It is a structural diagram of the pretreatment of the material to be processed according to the present invention.

[0026] Figure 4 It is an enlarged cross-sectional view of a welding portion of the present invention. DETAILED DESCRIPTION

[0027] The working principle of the present invention is further described below in conjunction with the accompanying drawings. It should be understood that the component parameters marked in each embodiment are preferred parameters rather than limitations on the scope of protection.

[0028] Embodiment 1 Overall structure of the present invention

[0029] The structural block diagram of the present invention is as follows: Figure 1 As shown, the connection diagram is as follows Figure 2 As shown, the system of the present invention is composed of a material pretreatment module 1, a laser module 2, a dual arc module 3, a blowing module 4, a weld monitoring module 5, and a post-weld processing module 7. The material pretreatment module 1 is composed of a cutting machine. The laser module 2 is composed of a laser main box 20 and a laser output head 21, wherein the laser beam emitted by the laser output head 21 is at a 45-degree angle with the first material 60 and the second material 61 of the workpiece to be processed. The dual arc module 3 is composed of a first arc welder 30, a first arc welding gun 31, a second arc welding gun 32, a second arc welder 33, and a welding machine controller 34. The blowing module 4 is composed of three inert gas storage devices 40. The weld monitoring module 5 is composed of an industrial high-definition camera 50 and a computer 51. The post-weld processing module 7 is composed of a high-temperature resistant heat preservation device made of silicon carbide. The first material 60 and the second material 61 of the material 6 to be processed are clamped and fixed on the welding platform by a clamp.

[0030] The first arc welding machine 30 of the double arc module 3 is equipped with a welding wire with the same composition as the first material 60, and the second arc welding machine 33 is equipped with a welding wire with the same composition as the second material 61, which are respectively connected to the first arc welding gun 31 and the second arc welding gun 32 to supply power and welding wire to the arc welding guns; they are also connected to the welding workpiece to apply an electromagnetic field to the welding area; the first arc welding gun 31 and the second arc welding gun 32 are movable relative to the gap, and are placed on both sides of the laser output head 21 one after the other along the gap direction, and the arc welding guns emit arcs The laser is guided, the front arc plays a preheating role, and the rear arc plays a gap-filling role, which greatly improves the welding quality; one end of the welding machine controller 34 is connected to the first arc welder 30 and the second arc welder 33, and is used to control the current and voltage parameters of the arc welder; the other end is connected to the computer 51, and the current and voltage values ​​of the arc welder are transmitted in real time. The computer 51 will feed back the comparison result with the calculated critical threshold value to the welding machine controller 34, so that the arc parameters can be adjusted up or down at any time according to the result to ensure the welding quality.

[0031] The laser main box 20 of the laser module 2 generates a laser with a laser power range of 2kW to 5kW and a duty cycle range of 50 to 100%. The laser beam emitted by the laser output head 21 is irradiated on the weld at a 45-degree angle. The first arc welding gun 31 and the second arc welding gun 32 of the double arc module 3 also act on the weld at a 45-degree angle, and are in the same horizontal plane with the laser one after the other, and are at an angle of 20-45 degrees with the laser beam. The arc voltage range is 20 to 40V and the current range is 100 to 200A. During the welding process, the welding machine controller 34 monitors the welding status of the first arc welding machine 30 and the second arc welding machine 33 in real time to deal with possible abnormal situations and ensure the stability and safety of the welding process. The welding robot synchronously moves the laser output head 21, the first arc welding gun 31 and the second arc welding gun 32 in the welding direction at the same speed, and the moving speed range is 3 to 6 mm / s. During the welding process, the three inert gas storage devices 40 of the blowing module 4 continuously provide shielding gas to the laser and arc devices, and blow away the spatter and residues during the welding process.

[0032] Example 2 Material pretreatment module

[0033] like Figure 3 As shown, the material pretreatment module 1 in the present invention uses a cutting machine to cut the welding side of the dissimilar materials to be processed into complementary grooves similar to a sawtooth structure, the width and depth of the grooves are both 1 cm, and another groove is opened at an interval of 1 cm, and this is repeated in sequence, wherein the first groove of the first material 60 is opened from the left 1 cm position, and one groove is opened at an interval of 1 cm; the first groove of the second material 61 is opened from the left edge position, and one groove is opened at an interval of 1 cm, and the two pieces of material with the grooves opened are spliced ​​in an L shape, and the effect of the mortise and tenon structure is utilized to make the welding more firm and the proportion of the materials at the welding point more uniform.

[0034] Example 3 Weld monitoring module

[0035] like Figure 4 As shown, the weld monitoring module 5 of the present invention monitors the convexity and concavity of the weld in real time. Since the laser beam and the arc are at an angle of 45 degrees to both sides of the workpiece, and the heat source is evenly distributed, the weld morphology is roughly symmetrical. The image data obtained by the industrial high-definition camera 50 is used by the image processing software of the computer 51 to obtain the height H of the convexity of the angle point in the workpiece in the opposite direction of the laser beam and the width B covered by the weld, and a critical threshold of the weld height corresponding to this weld width is calculated according to the Pythagorean theorem:

[0036]

[0037] The measured actual weld protrusion height H is compared with it. When it is higher than the critical threshold, the voltage and current values ​​of the first arc welder 30 and the second arc welder 33 are lowered through the welding machine controller 34; when it is lower than the critical threshold, the voltage and current values ​​of the first arc welder 30 and the second arc welder 33 are increased, and the voltage value is increased or decreased once by 2V, and the current value is increased or decreased once by 10A.

[0038] Example 4 Operation process of the present invention

[0039] The present invention selects heterogeneous materials of the same size to be processed, which are 20 cm long, 10 cm wide and 1 cm high. Before laser arc composite welding, the surface of the material to be processed is pretreated. First, the stains on the surface of the material to be welded are wiped off with alcohol, and the surface is continuously polished with sandpaper to remove the surface oxide film. Then, a metal cutting machine is used to open a rectangular groove of 1 cm long, 1 cm wide and 1 cm deep at a position 1 cm on the welding side of one of the materials, and another one is opened at an interval of 1 cm, for a total of 10 grooves; the grooves of the same size are opened starting from the edge of the welding side of the other material, and one is opened at an interval of 1 cm, for a total of 10 grooves. The two pieces of material form a complementary mortise and tenon structure that can be docked, and are well spliced ​​in an L-shape, which itself has a certain firmness. On this basis, the strength of the welding joint can also be greatly enhanced.

[0040] The power cord of the laser main box 20 is connected to the power supply, and the optical fiber line is connected to the computer 51. Turn on the laser, first adjust the laser output to an infrared spot to irradiate the welding area, determine the initial welding position, adjust the laser beam output by the laser output head 21, the first arc welding gun 31 and the second arc welding gun 32 to form a 45-degree angle with both sides of the workpiece, and place the two arc welding guns on both sides of the laser output head 21 one after the other and on the same horizontal plane at an angle of 20 to 45 degrees, connect the power of the two arc welding machines, adjust the arc voltage range to 20 to 40V and the current range to 100 to 200A, set the laser power to 2kW to 5kW, and after making all preparations, start the laser and the two arcs at the same time to act on the welding area, and move in the welding direction at the same speed through the robotic arm.

[0041] During the welding process, the gas storage device 40 continuously blows inert gas into the laser and arc to blow away the spatter and residue generated during the welding process, and the lens of the industrial high-definition camera 50 of the weld monitoring module 5 is aimed at the weld area to monitor the changes in the convexity and concavity of the weld in real time. According to the comparison between the monitoring results and the critical threshold, the laser and arc parameters are adjusted through the computer 51 and the welding machine controller 34 to achieve high-quality automated welding. Immediately after the welding is completed, the welding workpiece is moved to the silicon carbide high-temperature insulation device of the post-weld processing module 7 by a manipulator, and it is set to cool to room temperature in ten hours, which greatly slows down the cooling speed of the workpiece, increases the interface strength and mechanical properties, and avoids stress deformation and interface weakening caused by too fast cooling speed.

Claims

1. A heterogeneous material laser arc hybrid welding system, comprising a material pretreatment module (1), a laser module (2), a dual arc module (3), an air blowing module (4), a weld monitoring module (5), and a post-weld processing module (7); the material pretreatment module (1) is composed of a cutting machine; the laser module (2) comprises a laser main box (20) and a laser output head (21); the laser output head (21) is movable relative to the gap and emits a laser beam at an angle of 45° to act on the gap between two material clamping plates; the dual arc module (3) comprises a first arc welding machine (30), a first arc welding gun (31) , a second arc welding gun (32), a second arc welding machine (33) and a welding machine controller (34); the blowing module (4) includes three inert gas storage devices (40); the weld monitoring module (5) includes an industrial high-definition camera (50) and a computer (51), which are used to monitor the convexity and concavity of the weld in real time, and feed back the results to the laser main box (20) and the welding machine controller (34) through the computer (51); the post-weld processing module (7) is composed of a heat preservation device made of silicon carbide high-temperature resistant material, which is used to slow down the cooling rate of the workpiece after welding, eliminate stress and deformation, and increase plasticity and toughness; The laser mainframe box (20) is connected to a computer (51) via an optical fiber, and laser parameters are controlled by the computer (51). The laser mainframe box (20) is also connected to a laser output head (21); The three inert gas storage devices (40) provide protective gas to the laser and arc devices. The blown gas covers the arc and the molten pool, protecting the arc and the molten pool from the influence of oxygen and nitrogen in the air, preventing oxidation and nitridation, and reducing spatter generation, blowing away residues in the laser welding process, and improving the mechanical properties and corrosion resistance of the weld.

2. The laser arc hybrid welding system for dissimilar materials according to claim 1, characterized in that: The welding machine controller (34) is a Huandian IDP300 welding controller, which adjusts the current and voltage through the control circuit to control the temperature of the welding zone and the formation of the molten pool, and controls the cooling and solidification process of the molten pool by setting the welding time.

3. A method for laser arc hybrid welding of dissimilar materials, comprising the following steps: Step 1: Perform welding pretreatment on the dissimilar materials to be processed, and process rectangular grooves on the surface of the dissimilar materials to be processed, wherein the width and depth of the grooves are both 1 cm, and the groove interval is 1 cm, wherein the first groove of the first material (60) starts from the left 1 cm position, and one groove is opened at an interval of 1 cm; the first groove of the second material (61) starts from the left edge position, and one groove is opened at an interval of 1 cm; Step 2: Cross-fasten the first material (60) and the second material (61) in an L-shape and fix them on a welding platform with a clamp; Step 3: adjusting the position of the laser output head (21) so that the angle between the emitted laser beam and the first material (60) and the second material (61) is 45 degrees, and adjusting the first arc welding gun (31) and the second arc welding gun (32) to be placed one after the other along the gap direction on both sides of the laser output head (21) to form an angle of 20 to 45 degrees with the laser beam; Step 4: Setting the output power and duty cycle parameters of the laser through the computer (51) so that the laser mainframe (20) outputs the laser, setting the current and voltage parameters of the arc through the welding machine controller (34), and then starting the laser and the two arcs to work simultaneously, and the laser output head, the first arc welding gun (31) and the second arc welding gun (32) move in the direction of the gap extension at the same speed, and monitoring the convexity and concavity of the weld in real time through the weld monitoring module (5), and feeding back the results to the laser mainframe (20) and the welding machine controller (34) through the computer (51), so that the laser and arc parameters can be adjusted up or down at any time according to the results; While carrying out step 4, the blowing module (4) is turned on to deliver inert gas to the welding area to blow away the slag splashed during the welding process; Step 5: Immediately after welding is completed, the welded workpiece is placed in the silicon carbide high temperature resistant insulation device of the post-weld processing module (7) using a robot, and is set to cool to room temperature within ten hours to slow down the cooling speed, eliminate stress and deformation, and improve the strength of the welding interface.

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