Method and system for inhibiting pore defect in laser deep penetration welding of aluminum magnesium alloy

Abstract

The invention provides a method and a system for inhibiting an aluminum magnesium alloy laser deep penetration welding pore defect, and relates to the technical field of aluminum magnesium alloy laser welding, and the method comprises the following steps: S1, polishing the surface of an aluminum magnesium alloy welding plate, and carrying out chemical cleaning decontamination; s2, the aluminum-magnesium alloy welding plate is fixed through a welding tool, and the aluminum-magnesium alloy welding plate is restrained through a high-temperature clamp; s3, the aluminum-magnesium alloy welding plate is welded through double-light-spot laser, the front light spot is pretreated, and the rear light spot is subjected to deep penetration welding; s4, the scanning interval and the scanning width of the laser beams are adjusted and set through galvanometer parameters; and S5, the preset laser power, the preset welding speed and the preset shielding gas flow are adopted for completing laser welding. According to the method, high-quality welding of the medium-thickness plate aluminum alloy can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum-magnesium alloy laser welding, and in particular to a scanning laser welding method with added front preheating, and in particular to a method and system for suppressing porosity defects in aluminum-magnesium alloy laser deep fusion welding. Background Art

[0002] Aluminum-magnesium alloys have been widely used in lightweight manufacturing of large structural parts due to their corrosion resistance and high specific strength. Laser welding has been widely used in the connection of medium and thick plate structures due to its high efficiency, low heat input and large penetration depth. However, for aluminum-magnesium alloys, during the laser deep penetration welding process, due to the high reflection characteristics of aluminum itself and the low boiling point characteristics of magnesium, unstable laser energy absorption rate and keyhole wall impact are generated. Unstable keyhole depth and fluctuating keyhole walls can easily induce keyhole collapse and trap bubbles to form pore defects, which seriously endangers weld formation and strength. In view of the adverse effects of aluminum high reflection, for near-infrared fiber lasers, the main method is to modify the material surface or, for example, add a graphite layer with a higher absorption rate, but this will cause additional process costs.

[0003] In addition, with the development of beam shaping, scanning lasers such as annular, infinite and transverse have been widely used in porosity suppression research, but these scanning paths will inevitably cause strong and long-term heating of the molten pool on both sides of the path, which is not conducive to magnesium gasification control and has limited porosity suppression effect. At the same time, a more uniform energy distribution will sacrifice the depth of fusion, which goes against the original intention of deep fusion welding of medium and thick plates.

[0004] Therefore, due to the high reflectivity of aluminum-magnesium alloy to laser, the absorption rate of laser welding process is unstable, which causes the keyhole to fluctuate in the depth direction, resulting in the closure of the keyhole and the formation of pores. On the other hand, the low-boiling-point magnesium element vaporizes around the small hole wall to form bubbles that impact the small hole wall, causing the small hole to close and form pores. Summary of the invention

[0005] In view of the defects in the prior art, the present invention provides a method and system for suppressing porosity defects in laser deep fusion welding of aluminum-magnesium alloy.

[0006] According to a method and system for suppressing porosity defects in laser deep penetration welding of aluminum-magnesium alloys provided by the present invention, the scheme is as follows:

[0007] In a first aspect, a method for suppressing porosity defects in laser deep penetration welding of aluminum-magnesium alloy is provided, the method comprising:

[0008] Step S1: grinding the surface of the aluminum-magnesium alloy welding plate and performing chemical cleaning to remove dirt;

[0009] Step S2: Fix the aluminum-magnesium alloy welding plate with a welding fixture and restrain the aluminum-magnesium alloy welding plate with a high-temperature clamp;

[0010] Step S3: welding the aluminum-magnesium alloy welding plate by using a dual-spot laser, wherein the front spot performs pretreatment and the rear spot performs deep fusion welding;

[0011] Step S4: adjusting and setting the laser beam scanning interval and scanning width by using the galvanometer parameters;

[0012] Step S5: completing laser welding using a preset laser power, welding speed and shielding gas flow rate.

[0013] Preferably, in step S3, dual spots are used for welding, the diameter of the front spot is at least 3 times the diameter of the rear spot, and the thickness of the melted material heated by the front spot is 0.5-1 mm; the distance between the front and rear spots is 0.2-0.5 mm.

[0014] Preferably, in step S3, the front light spot and the rear light spot rotate in a spiral shape at the same time, and the rotation speed gradually increases from the inside to the outside. In a single spiral scanning cycle, the scanning speed starts from 0 to 50 mm / s and increases to 400 to 500 mm / s.

[0015] Preferably, in step S3, when the light beam is scanned in a spiral shape, the interval between the internal spiral lines is half of the focal diameter of the deep penetration welding laser spot, and a single spiral scanning cycle needs to contain 3 to 5 spiral lines.

[0016] Preferably, in step S4, the laser beam motion trajectory is controlled by a galvanometer oscillating and reflecting laser light method;

[0017] The laser scanning path is set to be spiral, and the scanning speed is gradually accelerated from the center of the spiral to the outside; the scanning speed is gradually accelerated from the initial 0 mm / s to 500 mm / s, the maximum scanning width is 1 mm, the scanning frequency is 150 Hz, the scanning interval is 0.1-0.3 mm, and the interlayer overlap rate is in the range of 40-60%.

[0018] Preferably, in step S5, different aluminum-magnesium alloy welding depths are matched with corresponding laser powers and welding speeds, the scanning interval and width are determined, 0 defocus is used, and the laser inclination angle is offset by 5°; at the same time, a protective gas is placed behind the beam to protect the molten pool.

[0019] In a second aspect, a system for suppressing porosity defects in laser deep penetration welding of aluminum-magnesium alloy is provided, the system comprising:

[0020] Module M1: Grind the surface of the aluminum-magnesium alloy welding plate and perform chemical cleaning and decontamination;

[0021] Module M2: Fix the aluminum-magnesium alloy welding plate with welding fixture and restrain the aluminum-magnesium alloy welding plate with high-temperature fixture;

[0022] Module M3: Dual-spot laser welding is used for aluminum-magnesium alloy welding plates, where the front spot is used for pretreatment and the rear spot is used for deep fusion welding;

[0023] Module M4: Use the galvanometer parameters to adjust and set the laser beam scanning interval and scanning width;

[0024] Module M5: Laser welding is performed using preset laser power, welding speed and shielding gas flow.

[0025] Preferably, in the module M3, dual light spots are used for welding, the diameter of the front light spot is at least three times the diameter of the rear light spot, and the thickness of the material heated by the front light spot is 0.5-1 mm; the distance between the front and rear light spots is 0.2-0.5 mm;

[0026] In the module M3, the front light spot and the rear light spot rotate in a spiral shape at the same time, and the rotation speed gradually increases from the inside to the outside. In a single spiral scanning cycle, the scanning speed starts from 0 to 50 mm / s and increases to 400 to 500 mm / s.

[0027] In the module M3, when the light beam is scanned in a spiral shape, the interval between the internal spiral lines is half of the focal diameter of the deep penetration welding laser spot, and a single spiral scanning cycle needs to contain 3 to 5 spiral lines.

[0028] Preferably, in the module M4, the laser beam motion trajectory is controlled by a galvanometer oscillating and reflecting laser method;

[0029] The laser scanning path is set to be spiral, and the scanning speed is gradually accelerated from the center of the spiral to the outside; the scanning speed is gradually accelerated from the initial 0 mm / s to 500 mm / s, the maximum scanning width is 1 mm, the scanning frequency is 150 Hz, the scanning interval is 0.1-0.3 mm, and the interlayer overlap rate is in the range of 40-60%.

[0030] Preferably, in the module M5, different aluminum-magnesium alloy welding depths are matched with corresponding laser powers and welding speeds, the scanning interval and width are determined, 0 defocus is used, and the laser inclination angle is offset by 5°; at the same time, a protective gas is placed behind the beam to protect the molten pool.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The present invention adds a scanning laser welding method with front preheating. The use of front preheating can significantly optimize the surface and root formation of the aluminum alloy welding weld. The front preheating effect of the laser beam action ring is used to ensure a stable laser absorption rate, which is beneficial to improving the stability of the welding process;

[0033] 2. The laser beam scanning form of the welding of the present invention gradually accelerates the migration to the outside, which suppresses the porosity defects while ensuring the deep penetration welding effect.

[0034] Other beneficial effects of the present invention will be explained in the specific implementation manner through the introduction of specific technical features and technical solutions. Through the introduction of these technical features and technical solutions, those skilled in the art should be able to understand the beneficial technical effects brought about by the technical features and technical solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0036] Figure 1 Schematic diagram of porosity suppression in laser welding with double-spot control and accelerated spiral scanning;

[0037] Figure 2 It is a longitudinal section of a single laser weld;

[0038] Figure 3 It is a longitudinal cross-sectional view of the scanning laser weld of the method of the present invention. DETAILED DESCRIPTION

[0039] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0040] The embodiment of the present invention provides a method for suppressing porosity defects in laser deep melting welding of aluminum-magnesium alloys, referring to Figure 1 As shown, it is mainly used for process-type porosity defects caused by keyhole instability during laser deep fusion welding of 5-10mm thick aluminum-magnesium alloy. By adopting a laser scanning form that gradually accelerates migration to the outside, the laser pinhole quickly engulfs the magnesium pores formed by magnesium vaporization, and finally escapes along the laser pinhole. At the same time, the laser scanning speed gradually increases, and the magnesium vaporization temperature range gradually decreases, and finally the porosity defect suppression of aluminum-magnesium alloy laser welding is achieved. The method specifically includes:

[0041] Step S1: Grind the surface of the 5 mm to 10 mm aluminum-magnesium alloy welding plate and use acetone to chemically clean and decontaminate it.

[0042] Step S2: Fix the aluminum-magnesium alloy welding plate with a welding fixture and restrain the aluminum-magnesium alloy welding plate with a high-temperature clamp.

[0043] Step S3: The aluminum-magnesium alloy welding plate is welded using a dual-spot laser, wherein the front spot performs surface pretreatment to melt the aluminum alloy surface to a depth of 0.5 to 1 mm, so that the high-power rear spot acts directly on the molten liquid surface to achieve stable deep-penetration welding.

[0044] The dual-spot welding used in this step has a diameter of at least three times the diameter of the rear spot, and the thickness of the heated material melted by the front spot is 0.5 to 1 mm. The distance between the front and rear spots is 0.2 to 0.5 mm; the two beams rotate in a spiral shape at the same time, and the rotation speed gradually increases from the inside to the outside. In a single spiral scanning cycle, the scanning speed starts from 0 to 50 mm / s and increases to 400 to 500 mm / s. When the light beam scans in a spiral shape, the interval between the internal spiral lines is half the focal diameter of the deep-penetration laser spot, and a single spiral scanning cycle needs to contain 3 to 5 spiral lines.

[0045] Step S4: Use the galvanometer parameters to adjust and set the laser beam scanning interval and scanning width. The laser beam motion trajectory is controlled by the galvanometer swinging and reflecting laser method. The laser scanning path can be set to a spiral shape, and the scanning speed gradually accelerates from the center of the spiral outward. The scanning speed gradually accelerates from the initial 0mm / s to 500mm / s, the maximum scanning width is 1mm, the scanning frequency is 150Hz, the scanning interval is 0.1-0.3mm, and the interlayer overlap rate is in the range of 40-60%.

[0046] Step S5: Complete laser welding using the preset laser power, welding speed and shielding gas flow rate. Different welding depths require matching different line energies, i.e., adjusting the laser power and welding speed. When the welding speed is determined, determine the appropriate scanning interval width according to the parameter selection method in step 4. Finally, 0 defocus and a laser inclination angle of 5° are used to avoid the adverse effects of laser reflection on the laser head. A shielding gas with a suitable flow rate, such as pure argon, is placed behind the beam to protect the molten pool.

[0047] The present invention also provides a system for suppressing porosity defects in laser deep fusion welding of aluminum-magnesium alloys. The system for suppressing porosity defects in laser deep fusion welding of aluminum-magnesium alloys can be realized by executing the process steps of the method for suppressing porosity defects in laser deep fusion welding of aluminum-magnesium alloys, that is, those skilled in the art can understand the method for suppressing porosity defects in laser deep fusion welding of aluminum-magnesium alloys as a preferred embodiment of the system for suppressing porosity defects in laser deep fusion welding of aluminum-magnesium alloys.

[0048] The system is designed to increase the scanning laser preheating at the front, which forms a thin layer of liquid to stabilize the laser absorption rate at the rear. The scanning path with gradually increasing speed and radius ensures the melting depth at a low speed in the early stage, while the rear part is quickly scanned to quickly remove the evaporated magnesium, thereby achieving high-quality laser weld formation, including:

[0049] Module M1: Grind the surface of the 5mm-10mm aluminum-magnesium alloy welding plate and use acetone chemical cleaning to remove dirt.

[0050] Module M2: Fix the aluminum-magnesium alloy welding plate with welding fixture and restrain the aluminum-magnesium alloy welding plate with high-temperature clamp.

[0051] Module M3: Dual-spot laser welding is used for aluminum-magnesium alloy welding plates. The front spot performs surface pretreatment to melt the aluminum alloy surface to a depth of 0.5 to 1 mm, so that the high-power rear spot directly acts on the molten liquid surface to achieve stable deep-melting welding.

[0052] The module uses dual spots for welding. The diameter of the front spot is at least three times the diameter of the rear spot, and the thickness of the heated material melted by the front spot is 0.5 to 1 mm. The distance between the front and rear spots is 0.2 to 0.5 mm. The two spots rotate in a spiral shape at the same time, and the rotation speed gradually increases from the inside to the outside. In a single spiral scanning cycle, the scanning speed starts from 0 to 50 mm / s and increases to 400 to 500 mm / s. When the beam scans in a spiral shape, the interval between the internal spiral lines is half the focal diameter of the deep melting welding laser spot, and a single spiral scanning cycle needs to contain 3 to 5 spiral lines.

[0053] Module M4: The laser beam scanning interval and scanning width are set by adjusting the galvanometer parameters. The laser beam motion trajectory is controlled by the galvanometer swinging and reflecting the laser. The laser scanning path can be set to a spiral shape, and the scanning speed gradually accelerates from the center of the spiral outward. The scanning speed gradually accelerates from the initial 0mm / s to 500mm / s, the maximum scanning width is 1mm, the scanning frequency is 150Hz, the scanning interval is 0.1~0.3mm, and the interlayer overlap rate is in the range of 40~60%.

[0054] Module M5: Use the preset laser power, welding speed and shielding gas flow to complete laser welding. Different welding depths require different line energy, that is, adjust the laser power and welding speed. When the welding speed is determined, determine the appropriate scanning interval width according to the parameter selection method in step 4. Finally, use 0 defocus and 5° laser inclination to avoid the adverse effects of laser reflection on the laser head. A shielding gas with a suitable flow, such as pure argon, is placed behind the beam to protect the molten pool.

[0055] Next, the present invention will be described in more detail.

[0056] The present invention provides a method for suppressing the porosity defect of laser deep fusion welding of aluminum-magnesium alloy. Combined with the causes of keyhole-type porosity in laser deep fusion welding of aluminum-magnesium alloy, a preheating device is added and a scanning form is designed to effectively improve the porosity defect, ensure the weld penetration, optimize the weld formation, solve the porosity problem of laser deep fusion welding, and provide a technical solution for the welding of 5-10mm medium and thick plate aluminum-magnesium alloy, expanding the scope of application. Mainly aimed at the high sensitivity of keyhole-type porosity defects in deep fusion welding of aluminum alloys with medium and thick plates, a preheating device is added and a scanning path is designed to effectively improve the porosity defect, ensure the weld penetration, optimize the weld formation, and solve the porosity problem of laser deep fusion welding of aluminum-magnesium alloys with 5-10mm medium and thick plates. In this implementation case, the test material is aluminum-magnesium (Al-6Mg) alloy, and the panel size is 200mm×100mm×10mm.

[0057] Step 1, polish the surface of the welding plate and use acetone or alcohol to chemically clean and decontaminate;

[0058] Step 2: Use welding fixture to fix, and use high temperature clamp to restrain the panel. The restraining position is 1 / 6 of the panel size away from the weld. Install 5 high temperature screws on both sides of the weld, and arrange them equidistantly from the edge of the panel.

[0059] Step 3, setting a low-power 1.5 kW laser beam in front of the action point of the high-power 5 kW laser beam;

[0060] Step 4, using the galvanometer parameters to adjust the scanning speed from 0 to 500 mm / s, the maximum scanning amplitude is 1 mm, the scanning frequency is 150 Hz, and the interlayer overlap rate is in the range of 40 to 60%;

[0061] Step 5, the welding speed is 2m / min, the laser head is tilted back 4 degrees, 0 defocus is used, and 20L / min argon gas is placed at 45° on the back side of the molten pool for protection.

[0062] The embodiment of the present invention provides a method and system for suppressing porosity defects in laser deep fusion welding of aluminum-magnesium alloys, ensuring high-quality forming of laser deep fusion welding of aluminum-magnesium alloys, utilizing the preheating effect of the front part of the laser beam action ring to ensure a stable laser absorption rate, while gradually accelerating the migration of point laser scanning to the outside to devour magnesium vaporization pores. The combination of the two ensures the forming quality of a single-pass laser deep fusion welding weld, and provides a convenient and effective process design idea for porosity defect control and performance optimization of laser welding of aluminum-magnesium alloys.

[0063] Those skilled in the art know that, in addition to realizing the system and its various devices, modules, and units provided by the present invention in a purely computer-readable program code, it is entirely possible to realize the same functions in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system and its various devices, modules, and units provided by the present invention can be considered as a hardware component, and the devices, modules, and units included therein for realizing various functions can also be regarded as structures within the hardware component; the devices, modules, and units for realizing various functions can also be regarded as both software modules for realizing the method and structures within the hardware component.

[0064] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A method for suppressing porosity defects in laser deep penetration welding of aluminum-magnesium alloy, characterized in that: include: Step S1: grinding the surface of the aluminum-magnesium alloy welding plate and performing chemical cleaning to remove dirt; Step S2: Fix the aluminum-magnesium alloy welding plate with a welding fixture and restrain the aluminum-magnesium alloy welding plate with a high-temperature clamp; Step S3: welding the aluminum-magnesium alloy welding plate by using a dual-spot laser, wherein the front spot performs pretreatment and the rear spot performs deep fusion welding; Step S4: adjusting and setting the laser beam scanning interval and scanning width by using the galvanometer parameters; Step S5: completing laser welding using a preset laser power, welding speed and shielding gas flow rate.

2. The method for suppressing porosity defects in laser deep penetration welding of aluminum-magnesium alloy according to claim 1, characterized in that: In step S3, dual light spots are used for welding, the diameter of the front light spot is at least three times the diameter of the rear light spot, and the thickness of the melted material heated by the front light spot is 0.5-1 mm; the distance between the front and rear light spots is 0.2-0.5 mm.

3. The method for suppressing porosity defects in laser deep penetration welding of aluminum-magnesium alloy according to claim 1, characterized in that: In step S3, the front light spot and the rear light spot rotate in a spiral shape at the same time, and the rotation speed gradually increases from the inside to the outside. In a single spiral scanning cycle, the scanning speed starts from 0 to 50 mm / s and increases to 400 to 500 mm / s.

4. The method for suppressing porosity defects in laser deep penetration welding of aluminum-magnesium alloy according to claim 1, characterized in that: In step S3, when the light beam is scanned in a spiral shape, the interval between the internal spiral lines is half of the focal diameter of the deep penetration welding laser spot, and a single spiral scanning cycle needs to contain 3 to 5 spiral lines.

5. The method for suppressing porosity defects in laser deep penetration welding of aluminum-magnesium alloy according to claim 1, characterized in that: In step S4, the laser beam motion trajectory is controlled by a galvanometer oscillating and reflecting laser light method; The laser scanning path is set to be spiral, and the scanning speed is gradually accelerated from the center of the spiral to the outside; the scanning speed is gradually accelerated from the initial 0 mm / s to 500 mm / s, the maximum scanning width is 1 mm, the scanning frequency is 150 Hz, the scanning interval is 0.1-0.3 mm, and the interlayer overlap rate is in the range of 40-60%.

6. The method for suppressing porosity defects in laser deep penetration welding of aluminum-magnesium alloy according to claim 1, characterized in that: In step S5, different aluminum-magnesium alloy welding depths are matched with corresponding laser powers and welding speeds, the scanning interval and width are determined, 0 defocus is used, and the laser inclination angle is offset by 5°; at the same time, a protective gas is placed behind the beam to protect the molten pool.

7. A system for suppressing porosity defects in laser deep penetration welding of aluminum-magnesium alloy, characterized in that: include: Module M1: Grind the surface of the aluminum-magnesium alloy welding plate and perform chemical cleaning and decontamination; Module M2: Fix the aluminum-magnesium alloy welding plate with welding fixture and restrain the aluminum-magnesium alloy welding plate with high-temperature fixture; Module M3: Dual-spot laser welding is used for aluminum-magnesium alloy welding plates, where the front spot is used for pretreatment and the rear spot is used for deep fusion welding; Module M4: Use the galvanometer parameters to adjust and set the laser beam scanning interval and scanning width; Module M5: Laser welding is performed using preset laser power, welding speed and shielding gas flow.

8. The system for suppressing porosity defects in laser deep penetration welding of aluminum-magnesium alloy according to claim 7, characterized in that: In the module M3, dual light spots are used for welding, the diameter of the front light spot is at least three times the diameter of the rear light spot, and the thickness of the material heated by the front light spot is 0.5-1 mm; the distance between the front and rear light spots is 0.2-0.5 mm; In the module M3, the front light spot and the rear light spot rotate in a spiral shape at the same time, and the rotation speed gradually increases from the inside to the outside. In a single spiral scanning cycle, the scanning speed starts from 0 to 50 mm / s and increases to 400 to 500 mm / s. In the module M3, when the light beam is scanned in a spiral shape, the interval between the internal spiral lines is half of the focal diameter of the deep penetration welding laser spot, and a single spiral scanning cycle needs to contain 3 to 5 spiral lines.

9. The system for suppressing porosity defects in laser deep penetration welding of aluminum-magnesium alloy according to claim 7, characterized in that: In the module M4, the laser beam motion trajectory is controlled by a galvanometer oscillating and reflecting laser light method; The laser scanning path is set to be spiral, and the scanning speed is gradually accelerated from the center of the spiral to the outside; the scanning speed is gradually accelerated from the initial 0 mm / s to 500 mm / s, the maximum scanning width is 1 mm, the scanning frequency is 150 Hz, the scanning interval is 0.1-0.3 mm, and the interlayer overlap rate is in the range of 40-60%.

10. The system for suppressing porosity defects in laser deep penetration welding of aluminum-magnesium alloy according to claim 7, characterized in that: In the module M5, different aluminum-magnesium alloy welding depths are matched with corresponding laser powers and welding speeds, the scanning interval and width are determined, 0 defocus is used, and the laser inclination angle is offset by 5°; at the same time, a protective gas is placed behind the beam to protect the molten pool.

Images