Nanosecond laser swing welding method for glass and metal

Abstract

The invention discloses a nanosecond laser swing welding method for glass and metal, and belongs to the technical field of laser processing. The invention aims to solve the problem that the existing short-pulse laser welding of glass and metal needs a complicated pretreatment process to improve the contact state of glass and metal. The method comprises the steps of 1, cleaning a to-be-welded metal surface; 2, naturally stacking the to-be-welded glass and the cleaned to-be-welded metal; thirdly, the position of a laser focal plane is adjusted, and laser penetrates through the to-be-welded glass to be focused on the to-be-welded area of the to-be-welded metal surface; 4, setting a laser scanning path through computer control software; 5, enabling the laser to swing in an overlapped manner on the basis of a laser scanning path; and 6, naturally cooling and solidifying. The nanosecond laser swing welding device is used for nanosecond laser swing welding of glass and metal.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser processing. Background Art

[0002] Glass has good optical properties, mechanical properties and corrosion resistance, and is widely used in important fields such as aerospace, automotive, biomedical engineering, optical sensing, etc., and is usually used in combination with other materials (such as metals). To make the most effective use of composite structural parts of glass and metal, it is necessary to connect them with high strength and no defects. Traditional methods for connecting glass and metal include riveting, bonding, welding, diffusion welding, etc. However, these methods often easily lead to insufficient joint strength or reliability and are difficult to meet the stringent service requirements of composite structural parts. Due to the significant differences in the physical and chemical properties of glass and metal, it is difficult to achieve an ideal connection.

[0003] Currently, ultra-short (femtosecond, picosecond) or short (nanosecond) pulse laser welding, due to its small heat-affected zone, can effectively reduce thermal deformation, improve connection accuracy and quality, and provides a potential way to achieve reliable connection between glass and metal. However, there are significant differences in the welding mechanisms of using ultra-short pulse and short pulse lasers to weld glass and metal. During ultra-short pulse laser welding, high-density plasma can be formed in the glass material through multi-photon ionization, thus achieving instantaneous melting and connection. Short pulse lasers rely on heat conduction to precisely control the energy input and action time to achieve orderly surface melting and connection. Among them, short laser welding has attracted much attention because it can take into account welding quality, equipment cost and process complexity, and is conducive to large-scale industrial production.

[0004] Despite the many advantages of short pulse laser welding, short pulse laser welding of glass and metal still faces challenges. The welding of glass and metal has strict requirements for the contact gap. An excessive gap will seriously affect the welding quality, resulting in insufficient connection strength or defects. Currently, in order to obtain high-quality welds, complex pre-treatment processes are usually required to improve the contact state between glass and metal. For example, polishing the metal surface before welding or precisely applying pre-pressure on the glass surface, and using the surface tension of liquid to assist welding. Although these methods can effectively improve the connection strength, they greatly increase the process complexity, increase production costs, reduce production efficiency, and increase the technical level requirements for relevant practitioners, etc. Therefore, there is an urgent need for a glass-to-metal welding process with low requirements for the contact gap, simple pre-welding treatment, and high efficiency and reliability. Summary of the Invention

[0005] The present invention aims to solve the problem that the short pulse laser welding of existing glass and metal requires complex pre-treatment processes to improve the contact state between glass and metal, and further provides a nanosecond laser oscillating welding method for glass and metal.

[0006] A nanosecond laser oscillating welding method for glass and metal, which is carried out according to the following steps:

[0007] I. Clean the surface of the metal to be welded to obtain the cleaned metal to be welded;

[0008] II. Naturally stack the glass to be welded and the cleaned metal to be welded on the welding platform to obtain the workpiece to be welded after natural stacking;

[0009] III. Adjust the position of the laser focal plane so that the laser passes through the glass to be welded and is focused on the welding area on the surface of the metal to be welded;

[0010] IV. Set the laser scanning path through the computer control software;

[0011] V. Under the conditions that the nanosecond laser power is 10W - 50W, the pulse width is 10ns - 350ns, the repetition frequency is 200kHz - 500kHz, the scanning speed is 30mm / s - 250mm / s, the swing amplitude is 100μm - 150μm, and the swing frequency is 500Hz - 750Hz, make the laser superimpose oscillation on the basis of the laser scanning path;

[0012] VI. After the laser scanning is completed, naturally cool and solidify, that is, complete the nanosecond laser oscillating welding method for glass and metal.

[0013] The beneficial effects of the present invention are:

[0014] The nanosecond laser oscillating welding method for glass and metal provided by the present invention can achieve uniform distribution of laser energy under the premise of ensuring welding quality, without the need for polishing treatment of the glass and metal surfaces before welding, and without applying external pressure during welding clamping, avoiding cracks in the glass caused by inappropriate clamping force during welding. The present invention not only greatly simplifies the welding process, but also fundamentally eliminates the risk of glass breakage caused by inappropriate selection of clamping force, significantly reduces the production cost, improves the welding success rate and production efficiency, and provides a more reliable solution for the precision welding of glass and metal.

[0015] The nanosecond laser oscillating welding method for glass and metal provided by the present invention can achieve uniform distribution of laser energy under the premise of the same heat input, promoting uniform melting and mixing of glass and metal. At the same time, it reduces the temperature gradient, avoids heat concentration leading to uneven heating of the glass and cracks, effectively improves the strength and quality of the welded joint, improves the welding success rate of glass and metal, expands the welding process window, and reduces the welding cost of glass and metal materials. Description of the Drawings

[0016] Figure 1For the nanosecond laser oscillating welding system of glass and metal in Example 1, 1 is a computer, 2 is a nanosecond laser, 3 is a mirror, 4 is a scanning galvanometer, 5 is a focusing field lens, and 6 is a test platform;

[0017] Figure 2 For the nanosecond laser oscillating welding scanning path of glass and metal in Example 1 and Comparative Examples 1 to 3;

[0018] Figure 3 For the surface morphology of the nanosecond laser oscillating welding joint of glass and metal in Example 1;

[0019] Figure 4 For the cross-sectional morphology of the nanosecond laser oscillating welding joint of glass and metal in Example 1;

[0020] Figure 5 For the laser energy distribution diagram of the nanosecond laser oscillating welding of glass and metal in Example 1;

[0021] Figure 6 For the surface morphology of the nanosecond laser welding joint of glass and metal without oscillation in Comparative Example 1;

[0022] Figure 7 For the cross-sectional morphology of the nanosecond laser welding joint of glass and metal without oscillation in Comparative Example 1;

[0023] Figure 8 For the laser energy distribution diagram of the nanosecond laser welding of glass and metal without oscillation in Comparative Example 1;

[0024] Figure 9 For the surface morphology of the nanosecond laser welding joint of glass and metal without oscillation in Comparative Example 2;

[0025] Figure 10 For the cross-sectional morphology of the nanosecond laser welding joint of glass and metal without oscillation in Comparative Example 2;

[0026] Figure 11 For the laser energy distribution diagram of the nanosecond laser welding of glass and metal without oscillation in Comparative Example 2;

[0027] Figure 12 For the surface morphology of the nanosecond laser oscillating welding joint of glass and metal in Comparative Example 3;

[0028] Figure 13 For the cross-sectional morphology of the nanosecond laser oscillating welding joint of glass and metal in Comparative Example 3;

[0029] Figure 14 For the laser energy distribution diagram of the nanosecond laser oscillating welding of glass and metal in Comparative Example 3. Detailed implementation mode

[0030] Specific Embodiment 1: A nanosecond laser oscillating welding method for glass and metal is carried out according to the following steps:

[0031] 1. Clean the surface of the metal to be welded to obtain the cleaned metal to be welded;

[0032] 2. Naturally stack the glass to be welded and the cleaned metal to be welded on the welding platform to obtain the workpiece after natural stacking;

[0033] 3. Adjust the position of the laser focal plane so that the laser passes through the glass to be welded and focuses on the welding area on the surface of the metal to be welded;

[0034] 4. Set the laser scanning path through the computer control software;

[0035] 5. Under the conditions that the nanosecond laser power is 10W - 50W, the pulse width is 10ns - 350ns, the repetition frequency is 200kHz - 500kHz, the scanning speed is 30mm / s - 250mm / s, the swing amplitude is 100μm - 150μm, and the swing frequency is 500Hz - 750Hz, make the laser superimpose swing on the basis of the laser scanning path;

[0036] 6. After the laser scanning is completed, naturally cool and solidify to complete the nanosecond laser oscillating welding method for glass and metal.

[0037] In this specific embodiment, by coupling the nanosecond laser and the beam swing, the direct welding of the glass and the metal in the natural stacking state can be realized. Before welding, use anhydrous ethanol or acetone to clean impurities such as moisture and oil on the surface of the metal to be welded, and then wipe the excess liquid with a dust-free cloth without additional polishing treatment. Stack the glass to be welded and the metal on the welding platform to keep them in the natural stacking state, and the maximum allowable gap between the glass and the metal can reach 45μm. Then check whether the welding equipment is in normal working condition. After confirmation, use the servo motor to control the scanning galvanometer to move up and down or use a precision welding platform to adjust the position of the laser focal plane so that it passes through the glass and focuses on the welding area on the metal surface. Set the welding parameters and set the laser scanning path through the computer control software to superimpose an appropriate swing on the basis of the weld movement path. Use the set process for welding. By performing beam swing while scanning along the pre-set path, the high-efficiency and high-quality connection between the glass and the metal can be realized. After the laser scanning is completed, the welding method of this embodiment is completed after natural cooling and solidification.

[0038] This specific embodiment can achieve good connection between the metal with a surface roughness (Ra) of 1.5μm - 2μm and the glass without grinding and polishing the metal to be welded before welding.

[0039] Through the method of this specific embodiment, under the condition of ensuring the welding quality, the use of fixtures can be avoided, and the glass cracks caused by inappropriate selection and uneven distribution of the clamping force in the traditional clamping method can be avoided. By eliminating the hidden danger of stress concentration during the welding process, it provides a basic condition for the formation of high-quality joints.

[0040] The beneficial effects of this embodiment are as follows:

[0041] The nanosecond laser oscillating welding method for glass and metal provided by this embodiment can achieve that without polishing the surfaces of the glass and metal before welding under the premise of ensuring the welding quality, and no external pressure needs to be applied during welding clamping, avoiding the generation of cracks in the glass caused by inappropriate clamping force during the welding process. This embodiment not only greatly simplifies the welding process, but also fundamentally eliminates the risk of glass breakage caused by improper selection of the clamping force, significantly reduces the production cost, improves the welding success rate and production efficiency, and provides a more reliable solution for the precision welding of glass and metal.

[0042] The nanosecond laser oscillating welding method for glass and metal provided by this embodiment can achieve uniform distribution of laser energy under the premise of the same heat input, promoting the uniform melting and mixing of the glass and metal. At the same time, it reduces the temperature gradient, avoids heat concentration leading to uneven heating of the glass and generating cracks, effectively improves the strength and quality of the welded joint, increases the welding success rate of glass and metal, expands the welding process window, and reduces the welding cost of glass and metal materials.

[0043] Specific embodiment two: The difference between this embodiment and specific embodiment one is that the material of the metal to be welded described in step one is aluminum alloy. Others are the same as specific embodiment one.

[0044] Specific embodiment three: The difference between this embodiment and one of specific embodiments one or two is that in step one, the surface of the metal to be welded is specifically cleaned with anhydrous ethanol or acetone, and then wiped with a dust-free cloth. Others are the same as specific embodiments one or two.

[0045] Specific embodiment four: The difference between this embodiment and one of specific embodiments one to three is that the surface roughness Ra of the metal to be welded described in step one is 1.5μm - 2μm. Others are the same as specific embodiment three.

[0046] Specific embodiment five: The difference between this embodiment and one of specific embodiments one to four is that the material of the glass to be welded described in step two is soda-lime glass; the thickness of the glass to be welded described in step two is 1mm - 2mm. Others are the same as specific embodiments one to four.

[0047] Embodiment Six: The difference between this embodiment and any one of Embodiments One to Five is that: the maximum gap of the workpieces to be welded after natural stacking in Step Two is 35μm - 45μm. Others are the same as those in Embodiments One to Five.

[0048] Embodiment Seven: The difference between this embodiment and any one of Embodiments One to Six is that: the laser scanning path in Step Four is linear, bow-shaped, grid-shaped, concentric circular, concentric rectangular or spiral-shaped. Others are the same as those in Embodiments One to Six.

[0049] Embodiment Eight: The difference between this embodiment and any one of Embodiments One to Seven is that: when the laser scanning path in Step Four is bow-shaped, let the longitudinal movement spacing of the laser be M, and M≥0.25mm. Others are the same as those in Embodiments One to Seven.

[0050] Embodiment Nine: The difference between this embodiment and any one of Embodiments One to Eight is that: the swing mode in Step Five is sine-shaped, circular, figure-eight-shaped or ∞-shaped. Others are the same as those in Embodiments One to Eight.

[0051] Embodiment Ten: The difference between this embodiment and any one of Embodiments One to Nine is that: the laser spot diameter in Step Five is 50μm - 60μm. Others are the same as those in Embodiments One to Nine.

[0052] The following examples are used to verify the beneficial effects of the present invention:

[0053] Example One:

[0054] A nanosecond laser swing welding method for glass and metal is carried out according to the following steps:

[0055] I. Clean the surface of the metal to be welded with absolute ethanol, and then wipe it with a dust-free cloth to obtain the cleaned metal to be welded;

[0056] II. Naturally stack the glass to be welded and the cleaned metal to be welded on the welding platform to obtain the workpieces to be welded after natural stacking;

[0057] III. Adjust the position of the laser focal plane to make the laser pass through the glass to be welded and focus on the welding area on the surface of the metal to be welded;

[0058] IV. Set the laser scanning path through the computer control software;

[0059] V. Under the conditions of a nanosecond laser power of 25W, a pulse width of 60ns, a repetition frequency of 250kHz, a scanning speed of 50mm / s, a swing amplitude of 150μm and a swing frequency of 750Hz, make the laser superimpose swing on the basis of the laser scanning path;

[0060] 6. After the laser scanning is completed, it is naturally cooled and solidified, thus completing the nanosecond laser oscillatory welding method for glass and metal.

[0061] The material of the metal to be welded described in Step 1 is 6061 aluminum alloy, and its size is 50 mm × 25 mm × 2 mm.

[0062] The surface roughness Ra of the metal to be welded described in Step 1 is 1.78 μm.

[0063] The material of the glass to be welded described in Step 2 is soda-lime glass, and its size is 20 mm × 20 mm × 2 mm.

[0064] The maximum gap of the workpieces after natural stacking described in Step 2 is 40 μm, and no fixture is used for clamping.

[0065] The laser scanning path described in Step 4 is in a bow shape. Let the lateral movement width of the laser be L, the longitudinal movement width be W, and the longitudinal movement spacing be M. L = W = 4.8 mm, and M = 0.3 mm.

[0066] The oscillation mode described in Step 5 is circular.

[0067] The laser spot diameter described in Step 5 is 50 μm.

[0068] Comparative Example 1: The difference between this comparative example and Example 1 is that there is no beam oscillation in Step 5. Others are the same as Example 1.

[0069] Comparative Example 2: The difference between this comparative example and Example 1 is that the scanning speed in Step 5 is 20 mm / s and there is no beam oscillation. Others are the same as Example 1.

[0070] Comparative Example 3: The difference between this comparative example and Example 1 is that the oscillation amplitude in Step 5 is 200 μm. Others are the same as Example 1.

[0071] Figure 1 For the nanosecond laser oscillatory welding system for glass and metal in Example 1, 1 is a computer, 2 is a nanosecond laser, 3 is a mirror, 4 is a scanning galvanometer, 5 is a focusing field lens, and 6 is a test platform. The laser beam emitted by the nanosecond laser 2 is conducted through the optical path by several mirrors 3 and then connected to the scanning galvanometer 4; the focusing field lens 5 is fixedly connected to the scanning galvanometer 4, and the two cooperate to accurately project the laser beam onto the surface of the workpiece on the test platform 6. The system controls the up and down movement of the scanning galvanometer 4 with high precision through a servo motor, thereby realizing the dynamic adjustment of the laser focal plane position and ensuring that the laser energy passes through the glass and accurately focuses on the area to be welded on the metal surface. In the welding system, the effective focal length of the focusing field lens 5 is set to 163.5 mm, and the laser beam focused by it forms a spot with a diameter of 50 μm.

[0072] Figure 2 The nanosecond laser oscillating welding scanning paths of the glass and metal in Example 1 and Comparative Examples 1 to 3; in Example 1 and Comparative Example 3, the laser scanning path is controlled by a computer to be in a "bow" shape, and beam oscillation is carried out while performing the "bow" shape scanning. In Comparative Examples 1 and 2, welding is carried out under the condition of no beam oscillation.

[0073] Figure 3 The surface morphology of the nanosecond laser oscillating welding joint of the glass and metal in Example 1; as can be seen from the figure, the scanning track is clear and continuous, and there are no obvious defects such as pores and cracks.

[0074] Figure 4 The cross-sectional morphology of the nanosecond laser oscillating welding joint of the glass and metal in Example 1; as can be seen from the figure, the glass and aluminum alloy have achieved uniform melting and mixing in the weld area, the mechanical interlocking structure is enhanced, and the crack defects in the glass melting area are effectively suppressed, verifying the mechanism of the joint strength improvement from the microscopic structure level.

[0075] Figure 5 The laser energy distribution diagram of the nanosecond laser oscillating welding of the glass and metal in Example 1; as can be seen from the figure, uniform energy distribution is achieved through oscillating scanning, and the peak value of the laser energy density is 5.06 mJ / mm 2 , avoiding the risk of thermal damage caused by local energy overload, and verifying the superiority of the oscillating welding process in energy regulation.

[0076] Figure 6 The surface morphology of the nanosecond laser welding joint of the glass and metal under the condition of no oscillation in Comparative Example 1; as can be seen from the figure, the surface morphology of the joint under the condition of no oscillation is visible, and the scanning track shows a gradually widening trend affected by the welding heat accumulation effect.

[0077] Figure 7 The cross-sectional morphology of the nanosecond laser welding joint of the glass and metal under the condition of no oscillation in Comparative Example 1; as can be seen from the figure, compared with Example 1, the melting and mixing of the glass and aluminum alloy in the no-oscillation welded joint is poor, and there are a large number of crack and pore defects in the weld area.

[0078] Figure 8 The laser energy distribution diagram of the nanosecond laser welding of the glass and metal under the condition of no oscillation in Comparative Example 1; as can be seen from the figure, the peak value of the laser energy density under the condition of no oscillation can reach up to 15.6 mJ / mm 2 , which is significantly higher than the oscillating process in Example 1.

[0079] Figure 9 The surface morphology of the nanosecond laser welding joint of the glass and metal under the condition of no oscillation in Comparative Example 2; as can be seen from the figure, the surface morphology of the joint under the condition of no oscillation is visible, and cracks appear at the weld edge.

[0080] Figure 10 The cross-sectional morphology of the glass-to-metal nanosecond laser welded joint under the condition of no oscillation in Comparative Example 2; as can be seen from the figure, compared with Example 1 and Comparative Example 1, the melting and mixing of glass and aluminum alloy in the non-oscillating welded joint is poor, and there are a large number of crack and pore defects in the weld area.

[0081] Figure 11 The laser energy distribution diagram of the glass-to-metal nanosecond laser welding under the condition of no oscillation in Comparative Example 2; as can be seen from the figure, under the condition of no oscillation, the peak value of the laser energy density can reach up to 39.16 mJ / mm 2 , which is significantly higher than the oscillation process in Example 1.

[0082] Figure 12 The surface morphology of the glass-to-metal nanosecond laser oscillating welded joint in Comparative Example 3; as can be seen from the figure, the scanning track is clear and continuous, and there are no obvious defects such as pores and cracks.

[0083] Figure 13 The cross-sectional morphology of the glass-to-metal nanosecond laser oscillating welded joint in Comparative Example 3; as can be seen from the figure, the glass and aluminum alloy have achieved uniform melting and mixing in the weld area, the mechanical interlocking structure is enhanced, and the crack defects in the glass melting area are effectively suppressed, which verifies the mechanism of the joint strength improvement from the microscopic structure level. However, compared with Example 1, the volume of the glass melting area in the joint cross-section is significantly reduced, resulting in a weakening of the mechanical interlocking strength between it and the glass base material.

[0084] Figure 14 The laser energy distribution diagram of the glass-to-metal nanosecond laser oscillating welding in Comparative Example 3; as can be seen from the figure, the uniform distribution of energy is achieved through oscillating scanning, and the peak value of the laser energy density is 3.7 mJ / mm 2 , avoiding the risk of thermal damage caused by local energy overload, and verifying the superiority of the oscillating welding process in energy regulation. However, under the condition of a large oscillation amplitude, the lower laser energy density results in a significant reduction in the volume of the molten glass.

[0085] Under the condition that the shear speed is 0.2 mm / s, a universal material testing machine is used to test the shear strength of the laser welded joints prepared in Example 1 and Comparative Examples 1 to 3. Three specimens are tested with the same welding parameters, and the average value of the shear strength of the three specimens is calculated as the final test result. The shear strength of the joint in Example 1 is 10.95 MPa, reaching a relatively high level of the welding strength of soda-lime glass, while the shear strength of Comparative Example 1 is only 1.7 MPa, significantly lower than 10.95 MPa of the beam oscillation process in Example 1. Under the condition of no oscillation, the shear strength of the welded joint in Comparative Example 2 is further reduced, only 0.3 MPa. In addition, when the oscillation frequency in Comparative Example 3 is 750 Hz and the oscillation amplitude increases to 200 μm, the shear strength of the welded joint is reduced compared with Example 1, which is 3.61 MPa.

[0086] Through the comparative analysis of the examples and the comparative examples, it can be seen that the beam oscillation process effectively reduces the temperature gradient in the weld area, reduces welding defects, enables the glass and metal to be uniformly melted in the natural stacking state by regulating the laser energy distribution, enhances the mechanical interlocking effect, significantly improves the joint strength and welding quality, and verifies the key role of beam oscillation in optimizing the laser welding performance of glass and metal in the present invention.

Claims

1. A nanosecond laser oscillating welding method for glass and metal, characterized in that It is carried out according to the following steps: First, clean the surface of the metal to be welded to obtain the cleaned metal to be welded; Second, naturally stack the glass to be welded and the cleaned metal to be welded on the welding platform to obtain the workpiece to be welded after natural stacking; Third, adjust the position of the laser focal plane so that the laser passes through the glass to be welded and is focused on the welding area on the surface of the metal to be welded; Fourth, set the laser scanning path through the computer control software; Fifth, under the conditions that the nanosecond laser power is 10W - 50W, the pulse width is 10ns - 350ns, the repetition frequency is 200kHz - 500kHz, the scanning speed is 30mm / s - 250mm / s, the swing amplitude is 100μm - 150μm, and the swing frequency is 500Hz - 750Hz, make the laser superimpose swing on the basis of the laser scanning path; Sixth, after the laser scanning is completed, naturally cool and solidify, that is, complete the nanosecond laser swing welding method of glass and metal.

2. The nanosecond laser swing welding method for glass and metal according to claim 1, characterized in that The material of the metal to be welded described in step one is aluminum alloy.

3. A nanosecond laser swing welding method for glass and metal according to claim 1, characterized in that In step one, cleaning the surface of the metal to be welded specifically means using anhydrous ethanol or acetone to clean the surface of the metal to be welded, and then wiping it with a dust-free cloth.

4. A nanosecond laser oscillating welding method for glass and metal according to claim 1, characterized in that The surface roughness Ra of the metal to be welded described in step one is 1.5μm - 2μm.

5. A nanosecond laser swing welding method for glass and metal according to claim 1, characterized in that The material of the glass to be welded described in step two is soda-lime glass; the thickness of the glass to be welded described in step two is 1mm - 2mm.

6. A nanosecond laser swing welding method for glass and metal according to claim 1, characterized in that The maximum gap of the workpiece to be welded after natural stacking described in step two is 35μm - 45μm.

7. A nanosecond laser oscillating welding method for glass and metal according to claim 1, characterized in that The laser scanning path described in step four is parallel linear, bow-shaped, grid linear, concentric circular, concentric rectangular or spiral linear.

8. A nanosecond laser swing welding method for glass and metal according to claim 7, characterized in that When the laser scanning path described in step four is bow-shaped, set the longitudinal movement spacing of the laser as M, and M≥0.25mm.

9. A nanosecond laser oscillating welding method for glass and metal according to claim 1, characterized in that The swing mode described in step five is sine-shaped, circular, figure-eight-shaped or ∞-shaped.

10. A nanosecond laser oscillating welding method for glass and metal according to claim 1, characterized in that The laser spot diameter described in step five is 50μm - 60μm.

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