[China Aluminum] high-brightness fiber laser (beam parameter product [BPP] < 1.5 mm-mrad) enables system integrators to achieve remote processing, enhance the safety of remote processing heads in the work, and through the rapid positioning of the beam The combination of scanning heads enables remote laser cutting, etching and welding of highly thermally conductive metals such as aluminum and copper as well as new and lightweight carbon fiber composites. High-power, high-brightness fiber lasers enable rapid development of remote laser scanning (RLS) applications. Compared with other technologies, RLS has more flexibility and faster processing speed, and it greatly shortens the processing cycle of large-size workpieces. High-brightness fiber laser Traditional fiber lasers use fiber coupling to couple multiple laser outputs together, resulting in a lower output laser brightness. Ennea's nLIGHT altaTM next-generation fiber laser uses an innovative architecture that combines pump diodes and drivers in separate pump modules. The gain fiber is installed in a configurable gain module that can deliver more than 8 kW of laser power. The gain module is based on a novel primary oscillator/power amplifier (MOPA) design that enables high-brightness laser output. In addition, Ennea lasers also use a reliable integrated backfire isolator to protect all modules from the effects of retroreflective light, enabling full-power, uninterrupted, and stable processing of high-reverse materials. These two technological innovations have played a crucial role in the application of RLS. The key to the design of the RLS system is the scan head's working distance, focal spot size, and scan range. One of the advantages of using a high-brightness fiber laser is that it can increase the working distance and the scanning range, and at the same time can obtain a smaller spot size, in order to increase the welding speed and increase the welding penetration. The two commercial RLS scan head products listed in the table (SCANLAB IntelliWELD and IntelliSCAN) demonstrate the benefits of higher brightness lasers (50 μm fiber core diameter). It can be seen from this example that the working distance of the scan head can be increased by more than 50%, while the focal spot size can be reduced by 14%. The nLIGHT laser can provide high-brightness output up to 8kW. Remote laser welding The choice of welding solution is a complex issue for every application. In general, the number of short welds increases, and is distributed over a large area (for example, doors, seat structures, and car body parts of a car assembly). The advantages of remote laser welding (RLW) are also greater than those of fixed optical head welding. Figure 1 shows a case where the post-processing cycle is shortened by up to 50% using the RLW technique. Examples include high-density weld seam welding, precision welding (a, b), and large-scale structural welding with multiple weld seams. In particular, we see from (c) that part of the weld of this part continues from the top plate to the bottom plate. This type of structure using traditional welding heads for welding is not easy to achieve. Figure 1. The vehicle assembly needs to weld the ends of a set of tubes to a larger structure (a). (b) The example shows a large (about 30 × 60 cm) car seat structure, which is a multi-layer structure that requires welding at the top and is welded through holes to the bottom layer (c) of the part. In addition, RLW can provide many advanced functions for welding process control. For example, if it is necessary to swing the welding point in the welding area, or the machining process includes complex welding shapes (circular, C-shaped, etc.), the scanning speed is adopted. And the accuracy will be better than using a robot to perform small-scale high-speed motion. The scanning speed of the RLW scan head can reach 90 to 180 meters per minute, while the conventional robot has a high movement speed of only about 10 meters per minute. When high-brightness fiber lasers are used to process high-heat-conducting materials, it is better to use small spots in order to maintain the stability of the welding holes. However, this processing method may cause the processing process to be excessively intense and generate a large amount of welding spatter. Experiments have shown that the high-speed positioning of a high-brightness laser with a remote scan head significantly reduces welding spatter, which is achieved by ensuring that the welding holes are stabilized by beam oscillation. Figure 2 shows that when welding copper and aluminum, if the beam swing mode is not used, welding spatter will be very serious. Once high-frequency swing beams are used, welding spatter is reduced. In addition, the exclusive anti-high anti-technology developed by Ennex laser is also indispensable in this application. By installing a protective device, the device is protected from the damage of the return light. When processing highly reflective metals such as copper and aluminum, the back-reflected light is unavoidable. Traditional lasers may cause unstable processing, destructive automatic shutdown, or even be scrapped due to the natural sensitivity to returned light. Figure 2. Observation of pure copper welding with no beam swing (a) and beam swing (b). The swing optimization shows no welding spatter (c). (df) Shows the effect of applying beam wiggle to aluminum, reducing welding spatter. (Photo: Fraunhofer IWS and SCANLAB, Dresden, Germany). Zhuzhou Zhirong Advanced Material Co., Ltd , https://www.zrcarbide.com
