Laser welding device and welding method thereof

Abstract

The present invention provides a laser welding device and a welding method thereof, belonging to the technical field of laser welding. The method comprises a laser outputting a laser with a frequency change according to a welding time period, and the laser scans the metal to be welded according to a preset path. In different welding time periods, lasers with different frequencies are output, and the laser frequency changes with the welding time period, so that the laser energy acting on the metal to be welded changes accordingly, and the laser energy is basically equal to the energy required for welding, thereby avoiding deformation of the metal to be welded due to excess laser energy. At the same time, stress is also avoided inside the metal to be welded, reducing the probability of deformation of the metal to be welded, and improving the welding quality.

Description

Technical Field

[0001] The present invention relates to the technical field of laser welding, and in particular to a laser welding device and a welding method thereof. Background Art

[0002] Laser welding is an efficient and precise welding method that uses a high-energy-density laser beam as a heat source. With the development of industry, laser welding is increasingly being used in the field of metal welding.

[0003] However, the existing laser metal welding technology is easily affected by the action time between the laser and the material (i.e., the pulse width is on the order of ms), which can easily lead to excessive energy and produce a large thermal effect. The excess energy will continue to act on the metal material, continuously impacting the welding material and liquefying the metal, causing the metal material to deform. When a laser pulse stops, the liquefied metal cools and condenses into a solid state, and stress is generated inside the solid metal, causing the deformation to become more serious. Summary of the invention

[0004] The object of the present invention is to provide a laser welding device and a welding method thereof, which can effectively reduce the probability of metal deformation after welding and improve the welding quality.

[0005] The embodiment of the present invention is achieved as follows:

[0006] One aspect of an embodiment of the present invention provides a laser welding method, which includes a laser outputting a laser with a variable frequency according to a welding time period, and the laser scanning a metal to be welded along a preset path.

[0007] Optionally, the laser outputs a laser with a frequency that changes according to the welding time period, and the laser scans the metal to be welded along a preset path, including: in a first welding time period, the laser outputs a laser of a first frequency; wherein the first welding time period is 0 to 20ms, and the first frequency is 20KHz to 40KHz; in a second welding time period, the laser outputs a laser of a second frequency; wherein the second welding time period is 20ms to 80ms, and the second frequency is 30KHz to 100KHz; in a third welding time period, the laser outputs a laser of a third frequency; wherein the third welding time period is 80ms to 100ms, and the third frequency is 10KHz to 30KHz.

[0008] Optionally, the laser outputs a laser with a frequency that changes according to the welding time period, and the laser scans the metal to be welded along a preset path, including: in a first welding time period, the laser is accelerated to 200mm / s to 1000mm / s for scanning; in a second welding time period, the laser scans at a uniform speed of 200mm / s to 1000mm / s; in a third welding time period, the laser decelerates from 200mm / s to 1000mm / s to 0 scanning.

[0009] Optionally, the laser is connected to a galvanometer, and the galvanometer is connected to a driver; the laser outputs a laser with a frequency that changes according to the welding time period, and the laser scans the metal to be welded along a preset path, including: the driver controls the movement of the galvanometer, and the galvanometer drives the laser to move and scan through the galvanometer.

[0010] Optionally, the galvanometer is also connected to a focusing lens along the emitting direction of the laser, and the laser is emitted through the galvanometer and the focusing lens in sequence; the laser outputs a laser with a frequency that changes according to the welding time period, and the laser scans the metal to be welded along a preset path, including: the laser scans along the preset path, and a plurality of interconnected circular spots are formed in sequence on the preset path; wherein the diameter of the circular spot is 20um to 100um, and the spacing between the plurality of circular spots is 1 / 1000 to 1 / 20 times the diameter of the circular spot.

[0011] Optionally, before the laser outputs laser light with a frequency varying according to the welding time period and the laser light scans the metal to be welded along a preset path, the method further includes: adjusting the laser pulse width range to be between 2ns and 350ns.

[0012] Optionally, before the laser outputs laser light with a frequency varying according to a welding time period and the laser light scans the metal to be welded along a preset path, the method further includes: adjusting the wavelength of the laser light to 1064 nm.

[0013] Another aspect of an embodiment of the present invention provides a laser welding device, which includes a laser and a controller connected to the laser, the controller controls the laser to emit laser light with a variable frequency according to a welding time period, and causes the laser to scan the metal to be welded along a preset path.

[0014] Optionally, the laser is also connected to a galvanometer, the galvanometer is connected to a driver, the driver and the controller are electrically connected, and the driver is controlled by the controller to drive the galvanometer to move, so that the laser emitted by the laser moves after passing through the galvanometer.

[0015] Optionally, the galvanometer is further connected to a focusing lens along the emitting direction of the laser, so that the laser is emitted after passing through the galvanometer and the focusing lens in sequence.

[0016] The beneficial effects of the embodiments of the present invention include:

[0017] The laser welding device and the welding method provided by the embodiment of the present invention include a laser outputting a laser with a frequency varying according to a welding time period, and the laser scanning the metal to be welded according to a preset path. In different welding time periods, lasers with different frequencies are output, and the laser frequency changes with the welding time period, so that the laser energy acting on the metal to be welded changes accordingly, and the laser energy is substantially equal to the energy required for welding, thereby avoiding deformation of the metal to be welded due to excess laser energy, and at the same time, avoiding stress generated inside the metal to be welded, reducing the probability of deformation of the metal to be welded, and improving welding quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 One of the flow charts of the laser welding method provided by the embodiment of the present invention;

[0020] Figure 2 The second flow chart of the laser welding method provided by the embodiment of the present invention;

[0021] Figure 3 The third flow chart of the laser welding method provided by the embodiment of the present invention;

[0022] Figure 4 A schematic diagram of laser scanning along a preset path provided by an embodiment of the present invention;

[0023] Figure 5 A schematic diagram of a circular spot structure formed by laser scanning provided in an embodiment of the present invention;

[0024] Figure 6 A schematic diagram of the structure of a laser welding device provided in an embodiment of the present invention;

[0025] Figure 7 This is a schematic diagram of a user interface of a laser welding device controller provided in an embodiment of the present invention;

[0026] Figure 8 The second schematic diagram of the user interface of the laser welding device controller provided in an embodiment of the present invention.

[0027] Icon: 101 - controller; 100 - laser; 110 - galvanometer; 120 - focusing lens; 130 - circular spot; D - diameter; d - spacing; t - spiral spacing; v - scanning speed; Ⅰ - first welding time period; Ⅱ - second welding time period; Ⅲ - third welding time period. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0031] Traditional laser welding generally uses solid lasers or continuous light lasers, but with the development of lasers and higher integration of products, laser welding is gradually developing in the direction of more sophisticated and wider welding materials. Considering that the precision of traditional laser welding is not high, the types of materials that can be welded are limited, and the maintenance cost and power consumption are relatively high; continuous light lasers are generally used for welding the same materials, and because of their relatively high average power, the thickness and width of the materials they weld are generally larger.

[0032] Alternatively, YAG laser is used to weld metal sheets with a thickness of less than 0.5mm. However, due to the high pulse energy output by the YAG laser, the laser impact force during welding is relatively large, resulting in a relatively large weld pool. When the high-temperature molten liquid metal solidifies, it will produce a contraction force, which will cause the welded metal sheet to deform and bend. In severe cases, obvious laser penetration marks can be seen on the back of the welded metal sheet.

[0033] For example, when a 1064nm YAG laser is used to weld stainless steel sheets, the laser energy and the heat generated during the action will cause the welded stainless steel to bend and deform, and laser welding marks can be seen on the back of the stainless steel. Traditional YAG welding, due to its long laser action time (1ms) and small adjustable frequency (1Hz~20KHz), makes it difficult to reduce the heat-affected zone, which will inevitably cause material deformation and stainless steel sheet welding.

[0034] On this basis, an embodiment of the present application provides a laser welding device and a welding method thereof, which solves the above-mentioned problem by changing the frequency of the laser in different welding time periods.

[0035] Embodiment 1

[0036] Please refer to Figure 6 This embodiment provides a laser welding device, which includes a laser 100 and a controller 101 connected to the laser 100. The controller 101 controls the laser 100 to emit a laser with a frequency varying according to a welding time period, and enables the laser to scan the metal to be welded along a preset path.

[0037] The laser 100 emits laser light, and the controller 101 controls the parameters of the laser light emitted by the laser 100. The parameters are set in advance by the controller 101, and the laser 100 emits laser light according to the set parameters.

[0038] The parameters that can be set include the frequency of the laser, the pulse width of the laser, the movement speed of the laser (ie, the scanning speed v of the laser), the preset path (laser scanning path), the single pulse energy of the laser, etc.

[0039] For example, the laser 100 can be set to emit a laser with a variable frequency. During the welding process, at different welding time periods, the laser with a variable frequency can prevent excess laser energy from acting on the metal to be welded, thereby reducing the thermal impact of welding, reducing the deformation of the metal to be welded, and making the weld appearance smooth.

[0040] The laser welding device provided in the embodiment of the present invention controls the frequency of the laser emitted by the laser 100 and changes the frequency of the laser in different welding time periods, so that the energy of the laser acting on the metal to be welded is controlled and the energy is not excessive. In this way, it is avoided that the excessive laser energy acts on the metal to be welded and causes the metal to be welded to deform. By controlling the frequency of the laser, the thermal impact of welding can be effectively reduced, the deformation of the metal to be welded can be reduced, the welding appearance is smooth, and the welding quality is improved.

[0041] Laser 100 can be a MOPA fiber laser, MOPA (Master Oscillator Power-Amplifier), fiber laser uses fiber-coupled output semiconductor laser for pumping, has higher energy conversion efficiency; and uses air cooling system for heat dissipation, has a more compact structure, smaller size, and cheaper price, and the integrated all-fiber design makes the system maintenance-free and convenient for customers to use; thus, large-scale production lines become possible.

[0042] Generally, during welding, the frequency of the laser is between 20KHz and 4000KHz, which can effectively reduce the thermal impact of welding. The frequency will be specifically set according to different welding materials, welding requirements, etc. For example, different frequencies are 30KHz, 100KHz, 300KHz, 800KHz and 2000KHz, etc.

[0043] The laser pulse width can also be set by the controller 101. After the laser pulse width is set, the laser pulse width remains unchanged during the welding process.

[0044] When the action time between the laser and the material is reduced to less than 350ns, the purpose of metal welding can be achieved and the desired effect can be achieved without leaving too much laser energy, thereby effectively controlling the influence of thermal effects and causing only slight or even no physical bending deformation of the metal to be welded. Generally, the pulse width of the laser can be set between 2ns and 350ns, with different pulse widths of 2ns, 10ns, 30ns, 60ns or 200ns, etc. The pulse width between 2ns and 10ns is more effective. The single pulse energy of the laser is 0.01mJ to 2mJ.

[0045] During welding, within a period of time, the laser emitted by the laser 100 will form a plurality of circular light spots 130 (laser light spots, i.e., welding spots) connected in sequence along a preset path. Adjacent circular light spots 130 are arranged in order and can overlap and be superimposed to a certain extent, or the edges of adjacent circular light spots 130 can be connected. A series of circular light spots 130 formed along the preset path is a weld, which connects two metals to be welded so that the two metals to be welded are welded into one.

[0046] The diameter D of the circular light spot 130 at the positive focus is 20um to 100um, and the spacing d between adjacent circular light spots 130 is 1 / 1000 to 1 / 20 times the diameter D of the circular light spot 130 , making the welding more stable. The spacing d of the circular light spots 130 is the center distance between two circular light spots 130 .

[0047] Specifically, the spacing d of the circular light spot 130 can be calculated by the pulse overlap rate, and the scanning speed v of the laser is 20mm / s to 1000mm / s, for example, the scanning speed v is 20mm / s, 50mm / s, 100mm / s, 200mm / s, 500mm / s, 600mm / s or 800mm / s.

[0048] The ratio of the scanning speed v to the frequency is the pulse overlap rate of the laser. The spacing d is the pulse overlap rate, which indicates the degree of overlap of the two circular light spots 130. The smaller the spacing d, the higher the pulse overlap rate. When the pulse overlap rate is 5±4.995, the welding effect is better.

[0049] For example, the pulse overlap rate of the laser is 0.005 (scanning speed v is 20 mm / s, frequency 4000 KHz), 0.05 (scanning speed v is 40 mm / s, frequency 800 KHz), 0.5 (scanning speed v is 100 mm / s, frequency 200 KHz), 1 (scanning speed v is 100 mm / s, frequency 100 KHz), 4 (scanning speed v is 200 mm / s, frequency 50 KHz), 6 (scanning speed v is 120 mm / s, frequency 20 KHz) or 8 (scanning speed v is 160 mm / s, frequency 20 KHz), etc.

[0050] The laser 100 is also connected to a galvanometer 110 , which is connected to a driver. The driver is electrically connected to a controller 101 , and the driver is controlled by the controller 101 to drive the galvanometer 110 to move, so that the laser emitted by the laser 100 moves after passing through the galvanometer 110 .

[0051] The laser emitted by the laser 100 is emitted through the galvanometer 110, and the galvanometer 110 can move by being driven by a driver. When the galvanometer 110 moves, the laser emitted by the galvanometer 110 moves accordingly. The speed of the laser movement is the scanning speed v of the laser. The laser scans along a preset path to weld the metal to be welded.

[0052] The galvanometer 110 is also connected to a focusing lens 120 along the emission direction of the laser 100, so that the laser is emitted after sequentially passing through the galvanometer 110 and the focusing lens 120. The focusing lens 120 converges the laser so that the laser energy can be concentrated for welding, thereby improving thermal efficiency and welding efficiency.

[0053] Embodiment 2

[0054] Please refer to Figure 1 and Figure 3 , this embodiment provides a laser welding method, which includes:

[0055] S100: adjusting the laser pulse width to a range between 2ns and 350ns, and adjusting the laser wavelength to 1064nm.

[0056] The laser parameters are set by the controller 101. The laser parameters include a pulse width between 2ns and 350ns and a wavelength of 1064nm. After the settings are completed, scanning begins. During the scanning, the above laser parameters remain unchanged.

[0057] Of course, the laser parameters are not limited to the above-mentioned pulse width and wavelength, and other parameters of the laser can also be set as needed.

[0058] S110: The laser 100 outputs a laser with a frequency that varies according to a welding time period, and the laser scans the metal to be welded along a preset path.

[0059] During the welding process, the total welding time is divided into several welding time periods, and each welding time period outputs a laser with a different frequency. At the same time, the preset path is correspondingly divided into corresponding path segments, and several path segments are connected to form a preset path. After welding, the preset path forms a weld.

[0060] The preset path is set according to the actual position where the metal to be welded needs to be welded. When the laser scans the preset path, a weld is formed, and the weld connects the two metals to be welded.

[0061] The preset path can be set in advance. The preset path includes a ring circle, a rectangle, a spiral line, a rhombus, or any other shape, which can be determined according to actual needs.

[0062] Lasers of different frequencies are output in different welding time periods, so that the laser energy acting on the metal to be welded will not be excessive, thereby avoiding deformation of the metal to be welded due to excessive laser energy.

[0063] For example, please refer to Figure 2 , the welding time period can be divided into three time periods:

[0064] S111: In the first welding time period I, the laser 100 outputs a laser of a first frequency; wherein the first welding time period I is 0 to 20 ms, and the first frequency is 20 KHz to 40 KHz.

[0065] In the first welding time period I, the laser accelerates the scanning motion, the laser accelerates to 200 mm / s to 1000 mm / s, and the first stage of scanning must be completed within 0 to 20 ms to scan the first path.

[0066] S112: In the second welding time period II, the laser 100 outputs laser light of a second frequency; wherein the second welding time period II is 20ms to 80ms, and the second frequency is 30KHz to 100KHz.

[0067] In the second welding time period II, the laser keeps scanning at a uniform speed, the scanning speed v is between 200 mm / s and 1000 mm / s, and the second stage of scanning is completed within 20 ms to 80 ms to scan the second path.

[0068] S113: In the third welding time period III, the laser 100 outputs laser light of a third frequency; wherein the third welding time period III is 80 ms to 100 ms, and the third frequency is 10 KHz to 30 KHz.

[0069] In the third welding time period III, the laser keeps scanning with a gradually decelerating motion, and the scanning speed v gradually decreases from 200mm / s to 1000mm / s to 0 speed when the scanning is completed, and the third stage of scanning must be completed within 80ms to 100ms to scan the third path.

[0070] The first path, the second path and the third path are connected in sequence to form a preset path, and after scanning, a weld is formed along the preset path. Figure 4 shown.

[0071] When the output lasers of different pulse widths and frequencies are applied to the metal materials to be welded, the action time between the laser and the material is reduced. The short-time pulse metal welding method has better effects and does not cause physical deformation of the material.

[0072] The movement of the laser is realized by the galvanometer 110 . The controller 101 controls the driver, and the driver controls the movement of the galvanometer 110 . The laser is emitted through the galvanometer 110 , and the galvanometer 110 drives the laser to move and scan.

[0073] The galvanometer 110 is also connected to a focusing lens 120 along the emission direction of the laser 100, and the laser is emitted sequentially through the galvanometer 110 and the focusing lens 120. The focusing lens 120 focuses the laser to concentrate the laser energy, thereby improving the energy utilization rate.

[0074] The laser scans along a preset path. In an instant, the laser forms a laser spot (circular spot 130) on the preset path. During the continuous scanning time, a series of laser spots are formed. These laser spots are arranged in an orderly manner, such as Figure 4 shown.

[0075] A plurality of interconnected circular light spots 130 are sequentially formed on a preset path; wherein, Figure 5 As shown, the diameter D of the circular light spot 130 is 20 um to 100 um, and the spacing d between the plurality of circular light spots 130 is 1 / 1000 to 1 / 20 times the diameter D of the circular light spot 130 .

[0076] It should be noted that the MOPA pulse fiber laser can achieve real-time frequency adjustment during the laser opening process, and can achieve sudden and gradual changes in frequency parameters to change the pulse overlap rate.

[0077] Frequency mutation: When the speed of the galvanometer 110 remains unchanged, different frequencies are output according to different welding time periods. The number of welding time periods can be adjusted by the controller 101 , and the duration of each welding time period can also be adjusted by the controller 101 .

[0078] For example, the output frequency is 20KHz in the period of 0-20ms, 30KHz in the period of 20ms-80ms, and 1KHz in the period of 80ms-100ms. The frequency change is a sudden change.

[0079] Frequency gradient: When the speed of the galvanometer 110 remains unchanged, the frequency is set to automatically change from a specific frequency value to a frequency value within a certain welding time period, and the intermediate frequency changes are uniform. In this way, the controller 101 will automatically change the intermediate frequency value according to the set frequency starting point and frequency end point.

[0080] For example, for the 0.1mm stainless steel and 0.1mm stainless steel stitch welding test, the conventional test parameters are set to scan speed v 1000mm / s, frequency 100KHz, pulse width 60ns, power 50W, spiral pitch t (such as Figure 4As shown, the laser scanning forms a spiral track, and the distance between adjacent spiral lines is the spiral pitch t) is 0.06mm; the frequency conversion parameters use a frequency of 40KHZ in the first welding time period I, a frequency of 100KHZ in the second welding time period II, and a frequency of 30KHZ in the third welding time period III. The frequency is gradually changed, and other parameters are the same as the conventional test; the results show that the frequency conversion in different time periods can optimize the problems of the first point and the tail point caused by the acceleration and deceleration of the galvanometer 110, and avoid the problem of welding through the edge or center point of the thin sheet material. It can also optimize the thermal impact of the weld point, reduce the thermal deformation of the welding material, and improve the welding quality requirements.

[0081] During specific welding, the size of the light spot (circular spot 130) when the laser passes through the focusing lens 120 is first calculated, and then the appropriate scanning speed v and pulse overlap rate are calculated in combination with the set laser pulse and frequency; then a 1064nm pulse laser is used for metal welding.

[0082] An application example is the welding of studs (stainless steel) on the middle plate (nickel-plated copper) of the iPhone 8 mobile phone. The welding can be performed directly at the focal position without causing deformation of the middle plate of the mobile phone. It can also be used for welding the middle plate (nickel-plated copper) and middle frame (aluminum alloy) of the iPhone 8 mobile phone, welding of the camera module of the iPhone 8 mobile phone, welding of the pole ears of the power battery series, welding of the antenna shrapnel of the Huawei series, welding of precision electronic devices, etc. The application range is very wide.

[0083] Since most fiber lasers have an infrared wavelength, mostly 1064nm, they have a thermal effect on most materials, especially some thinner metal sheets; for example, the material of the positive pole ear of the battery is a 0.1mm aluminum bar, and a 0.1mm nickel bar needs to be welded to the 0.1mm aluminum bar as the positive pole ear. However, the MOPA fiber laser 100 is highly variable, and it can change some of its own parameters to try to avoid some bad effects. For example, different pulse widths and frequency parameters are used for welding the positive pole ears of 0.1mm nickel and aluminum. In addition, the frequency conversion function will correspondingly reduce the deformation caused by the heat of welding and improve the thermal effect at the end of welding, such as using parameters of 30ns, 160k and 50mm / s. In this way, it can be applied to laser welding of thin metal materials.

[0084] Another example of application is Figure 7As shown, the fiber laser 100 is set so that the fiber laser 100 can emit light normally and be controlled. Through calculation, after the laser is converged by the focusing lens 120, the diameter D of the circular spot 130 at the positive focus is 20 microns, the pulse frequency of the laser 100 is set to 30KHz, the scanning speed v is set to 400mm / s, and the helical pitch is set to 0.08 mm. The diameter D of the circular spot 130 can be adjusted by changing the diameter D of the helical line.

[0085] For example, Figure 8 As shown, the power of the laser 100 is set to 30W, the laser pulse width is set to 200ns, and the frequency is set to 30KH. At this time, the corresponding single pulse energy is 1 millijoule (mJ). The scanning speed v of the laser 100 is 400mm / s, and the laser is focused after passing through the focusing mirror. The diameter D of the circular spot 130 is 20um, and the pulse overlap rate is 13.33 at this time; the laser energy and the pulse overlap rate at this time are sufficient to melt the upper metal, and transfer the heat to the lower material and melt it, so as to achieve the purpose of welding. Moreover, since the welding point of each pulse on the metal material is very small (20um~100um), the pulse overlap rate is relatively low, so that after melting the welded metal, the remaining laser energy is also small, and it will no longer produce a large thermal effect on the welded metal. On the other hand, the frequency conversion function is added at the end of the welding, so that the final output frequency is lower and the overlap rate is reduced, so as to achieve the purpose of metal welding without bending and deforming the metal welding material.

[0086] The laser welding method provided in the embodiment of the present invention outputs lasers of different frequencies in different welding time periods. The laser frequency changes with the welding time period, so that the laser energy acting on the metal to be welded changes accordingly. The laser energy is basically equal to the energy required for welding, thereby avoiding deformation of the metal to be welded due to excess laser energy. At the same time, it also avoids the generation of stress inside the metal to be welded, reduces the probability of deformation of the metal to be welded, and improves the welding quality.

[0087] In this laser welding method, the controller 101 provides a variable frequency parameter to the laser 100. After receiving the variable frequency signal, the MOPA fiber laser 100 will also emit a variable frequency accordingly, so that the thermal impact of welding is reduced, the deformation is reduced, and the welding appearance is smooth; especially at the beginning and end of the light emission stage, because the acceleration of the galvanometer 110 is not fast enough, the laser pulse overlap is large, so there is a phenomenon in the prior art that the thermal impact of the welded metal sheet in the beginning and end area of ​​welding is large or the metal sheet is penetrated. By modulating the frequency lower at the beginning and end of welding by the controller 101, the deformation problem can be avoided, and the bending deformation phenomenon can be effectively reduced. During welding, the metal to be welded will not be physically bent and deformed. It is suitable for different types of metal welding, including metal sheets, such as the substrate in the mobile phone, the metal shell of digital products such as the tablet, and also includes 0.1mm stainless steel welding aluminum alloy, 0.2mm brass welding stainless steel, 0.15mm nickel sheet welding aluminum, etc., all of which have high market application value.

[0088] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A laser welding method, characterized in that: The method comprises: The laser outputs a laser with a frequency variation according to a welding time period, wherein the welding time period includes a first welding time period, a second welding time period and a third welding time period, and the laser performs accelerated scanning, average speed scanning and decelerated scanning in the three welding time periods in sequence; the laser scanning the metal to be welded according to a preset path includes: In a first welding time period, the laser outputs a laser of a first frequency; wherein the first welding time period is 0 to 20 ms, and the first frequency is 20 KHz to 40 KHz; In a second welding time period, the laser outputs a laser of a second frequency; wherein the second welding time period is 20 ms to 80 ms, and the second frequency is 30 KHz to 100 KHz; In a third welding time period, the laser outputs a laser of a third frequency; wherein the third welding time period is 80 ms to 100 ms, and the third frequency is 10 KHz to 30 KHz; the laser outputs a laser of a frequency varying according to the welding time period, and the laser scans the metal to be welded along a preset path, including: During the first welding time period, the laser is accelerated to scan at 200 mm / s to 1000 mm / s; During the second welding time period, the laser scans at a uniform speed of 200 mm / s to 1000 mm / s; In the third welding time period, the laser is decelerated from 200 mm / s to 1000 mm / s to 0 scanning; The preset path is a spiral line, and the pulse overlap rate of the laser in the third welding time period is lower than the pulse overlap rate of the laser in the first welding time period.

2. The laser welding method according to claim 1, characterized in that: The laser is connected to a galvanometer, and the galvanometer is connected to a driver; the laser outputs a laser with a frequency that changes according to the welding time period, and the laser scans the metal to be welded along a preset path, including: The driver controls the movement of the galvanometer, and the galvanometer drives the laser to move and scan through the galvanometer.

3. The laser welding method according to claim 2, characterized in that: The galvanometer is also connected to a focusing lens along the emission direction of the laser, and the laser is emitted through the galvanometer and the focusing lens in sequence; the laser outputs a laser with a frequency that changes according to the welding time period, and the laser scans the metal to be welded along a preset path, including: The laser scans along the preset path, and sequentially forms a plurality of interconnected circular light spots on the preset path; wherein the diameter of the circular light spot is 20 um to 100 um, and the spacing between the plurality of circular light spots is 1 / 1000 to 1 / 20 times the diameter of the circular light spot.

4. The laser welding method according to claim 1, characterized in that: Before the laser outputs a laser with a frequency varying according to a welding time period and the laser scans the metal to be welded along a preset path, the method further includes: The pulse width of the laser is adjusted to be between 2ns and 350ns.

5. The laser welding method according to claim 1, characterized in that: Before the laser outputs a laser with a frequency varying according to a welding time period and the laser scans the metal to be welded along a preset path, the method further includes: The wavelength of the laser was adjusted to 1064 nm.

6. A laser welding device, applied to the laser welding method according to any one of claims 1 to 5, characterized in that: The device comprises a laser and a controller connected to the laser. The controller controls the laser to emit laser light with a variable frequency according to a welding time period, and enables the laser to scan the metal to be welded along a preset path.

7. The laser welding device according to claim 6, characterized in that: The laser is also connected to a galvanometer, and the galvanometer is connected to a driver. The driver is electrically connected to the controller, and the driver is controlled by the controller to drive the galvanometer to move, so that the laser emitted by the laser moves after passing through the galvanometer.

8. The laser welding device according to claim 7, characterized in that: The galvanometer is also connected to a focusing lens along the emitting direction of the laser, so that the laser is emitted after passing through the galvanometer and the focusing lens in sequence.

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