Application of High Power Laser Scanning Galvanometer Welding

in Here is your first Forum Fri Oct 28, 2016 7:07 pm
by Eyes123456 • 30 Posts

Scanning galvanometer is an excellent vector scanning device, it is a special swing motor, the basic principle is the power coil in the magnetic field to generate torque, but the galvanometer can not rotate like an ordinary motor can only deflection, deflection angle and current Is proportional to, as with the galvanometer, the difference is that the lens replaces the hands. The system consists of laser, beam expander, mirror, motor base, galvanometer motor, X and Y mirrors, F-THETA focusing lens group and so on. The X- and Y-axis mirror mirrors and F- THETA focusing lens is the most important part of the system. The blue laser pointer beams are incident on the galvanometer in pulse or continuous mode. The two mirrors can be scanned along the X and Y axes respectively. The computer can control the reflection angle of the mirror to realize the deflection of the laser beam to weld the material to be processed. The focal plane of the F-THETA mirror is a flat plane, which has the effect of flat-field focusing and can be used in different directions of the incident angle of the laser beam (far Field and near field), the focal plane of the scanning system can be coincident with the surface of the workpiece to be processed, and the uniformity of the welding can be ensured.

Low power laser scanning galvanometer welding usually refers to the use of 1000W laser power below, to Nd-YAG pulse laser or fiber laser as welding light source, scanning galvanometer as the output device laser galvanometer welding system; with burning laser pointer spot moving speed (3000mm / S), high positioning accuracy (0.001mm), welding range, no water cooling and other characteristics in the IT, battery manufacturing industry has a large number of applications, including 18650 battery and its module manufacturing the most widely used, as shown in Figure 2, Including: 18650 cap explosion-proof valve welding, cap aluminum ring welding, cap - electrode ear welding, mold Group busbar welding, etc., almost 18650 battery manufacturing laser welding will use scanning galvanometer laser welding system. 18650 Cap - the electrode ear welding is usually done in the automated assembly line, the workpiece flow to the galvanometer welding head, the fixture clamping workpieces, galvanometer high-speed completion of welding, welding time less than 1 second, Han precision laser welding Division for the development of these applications, ST300 high-speed time laser welding machine, an ST300 laser can also be combined with a few galvanometer welding system, the work by the laser within the high-speed galvanometer swing each pulse laser output to each vibration distribution Mirror system, make full use of laser power, such as received four galvanometer system, 1 second species can be completed more than four battery ear welding. The 18650 module manifold in Figure 2.d. is a device for several tens to hundreds of battery electrodes in a parallel module, usually consisting of a thin copper plate and a thin nickel plate, requiring a laser to weld the two together, Distributed in the 50 * 30cm or more range, the use of galvanometer system welding, laser beam can be 3000mm / s speed quickly jump between the various solder joints, several times faster than other 20000mw laser pointer welding.

High power laser galvanometer welding usually 1000w and above laser power laser as welding laser source, often with 4000-6000w fiber laser, high-speed penetration welding 2-3mm aluminum and aluminum alloy. Higher laser power means that lenses need to withstand higher heat, which the lens material, lens coating, heat dissipation structure, manufacturing processes and assembly processes have put forward great demands. First of all, because the lenses need to bear the power is high, the lens itself is required to have a strong thermal stability, which led to the lens Xiao material selection is very simple, can not use more than a few minutes of refractive index combination design, so high power flat field Lens and collimator optical design greatly increased the difficulty; followed in order to withstand greater energy of the laser, coating process requirements are extremely stringent, the need for more professional coating equipment and a more rational film; Third, the 3000mw laser pointer power is very large , Will inevitably bring the system temperature rise, the system cooling must be resolved must be the most important, it is necessary to ensure that the optical components, electrical components to maintain the operating temperature in the appropriate range, but also to ensure absolute reliability in the course of work And the rationality of the layout of cooling lines, water-cooled system needs to be repeated trial and design changes to confirm the best results. After a large number of research and development, in 2015, Han's Laser Precision Welding Division launched the first self-developed industrial high-power laser galvanometer processing system Dragon series, Dragon series and 6kw and below fiber laser processing applications, especially for power battery module Group of laser welding.

At present, the development of new energy vehicles into a critical period, the lack of current production capacity of power batteries, scanning galvanometer laser welding system, welding speed, high strength, the welding process to achieve accurate positioning, easy to automate the welding process, galvanometer system installed in the robot , Flexible remote welding can be realized, with a large degree of freedom of space, in the welding of battery modules, batteries, soft connecting piece, battery explosion-proof valve and other processes are applied. Flexible remote scan welding: high power 2000mw laser pointer scanning galvanometer system usually with a larger focal length F-THETA focus lens, focal length is usually not less than 350mm, scanning range. Dragon Series scanning galvanometer processing system is usually with a focal length of 460mm F-THETA focus lens, welding range of 220 * 180mm, do not move the scanning galvanometer system in the same fixture can be placed in a number of the battery cover Soft-core welding, welding position can be prepared by software visualization. The galvanometer mounted on the manipulator can be flexibly welded to a wide range of battery modules in a range of 1 to 2m. Dragon scanning galvanometer processing system 3 seconds to complete the three battery cover soft connection welding.

Faster spot jump speed: Because the scanning galvanometer is deflected by the lens high speed, so that the reflected laser beam irradiation to different positions, the spot movement speed can reach 3000mm / s, that is, jump from one welding position to another position, the speed can be Up to 10 times higher than that of conventional servo motor platforms, such as welding a battery module of 16 47178 batteries and 32 electrode connecting pieces, and a servo platform for 100mw laser pointer spot position movement Requires at least 14 seconds, and by the robot mounted on the Dragon scanning galvanometer system welding, the equipment in the spot position on the movement only takes 7 seconds, a larger module to better reflect the efficiency difference.

High speed and stable welding complex trajectory: For the screw guide type servo motor platform system, high speed drive welding head movement complex trajectory, especially in the turning radius, the welding head movement speed will be reduced, resulting in the welding process Of the speed of instability, affecting the welding effect. Single oscilloscope welding arc or other complex trajectory when there will not be these problems, such as high-power laser galvanometer system in the welding of a number of batteries soft connecting piece, the laser can be 200-300mm / s speed welding circular trajectory , Some modules will also be used to track the way S-shaped welding. Spiral trajectory: As a high energy beam welding, the larger aspect ratio of the weld is a major feature of laser welding, but sometimes we do not want to weld the aspect ratio is too large, for example, in the battery module connector welding , It is usually necessary to have a larger width of the weld (to increase the current-carrying area) and to reduce the depth of the weld (to use a thinner battery pole for greater cell space.) Using helical trajectory welding, The spot along the welding direction of high-speed rotary motion, can not change the external optical path conditions, to obtain the different aspect ratio of the weld.

Large focus to bring the stability: As the Dragon Series galvanometer with F-THETA lens focal length 460mm, larger focal length when it has a greater depth of focus (3-5mm), that is, within a certain height welding, the workpiece Figure 8 is a two-layer 1.5mm aluminum plate penetration welding, the workpiece in the scanning galvanometer can be obtained under different focal positions of the welding seam (Figure 1), the workpiece can be obtained, Penetration, melting width data, can be seen from the data, in the range of +2 to -3mm, weld penetration, melting width change little. Another lens in 500mm above the working distance, the lens lens is not susceptible to welding spatter, but also brings better welding stability.

Compared with the traditional 200mw laser pointer welding, scanning galvanometer laser welding is the biggest advantage is not limited by the motor speed, vibration in the lens of the X, Y lens rapid swing, can be easily achieved in a wide range of arbitrary curve in the plane of high-speed Welding, and better reflect the high-speed laser welding efficiency advantages and technological advantages. Especially high-power laser scanning galvanometer welding system, more and more customers become the choice of large-scale production equipment, welding from the module gradually to the development of other batteries welding products, I believe that in the future large-scale manufacturing of power batteries There will be more extensive and widespread application.




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