Application of laser welding technology in Volkswagen

As an advocate of the use of laser welding in the production of automotive structural parts, the achievements of Volkswagen AG are undoubtedly enviable. According to Dr. Klaus Loeffler (Director of Welding Process at Volkswagen AG), he spoke at the 12th Annual Automotive Laser Application Symposium organized by the University of Michigan, claiming that Volkswagen had applied lasers to bodywork since 1993. Large-scale production applications are roof welding in 1996. By 1997, three models had laser-welded roofs. Over time, more models and more application methods have joined the ranks. According to Dr. Klaus Loeffler, it is undoubtedly the Volkswagen Golf V to say which model of the car uses the most laser manufacturing technology. This model has a total of 70 meters of laser welded seams, which is not surprising. No model can compare with it. So does this mean that spot welding has disappeared from the Golf model? No, Loeffler replied that the Golf V still has about 1,400 spot welds (compared to 4,608 spot welds for Golf IV models and only 1.4 meters for laser welding), arc welding (7 m) and adhesives. (30 meters). He admits that the Golf V model is actually “more or less the starting point for spot welding”, which means that when developing the next model, the company will have room for further structural improvements (Golf V compared to its predecessor model, Increased static torsional stiffness of over 80%, dynamic torsional stiffness of over 15%, and dynamic deflection of more than 35%) and weight reduction (reduced edge width promotes substantial reduction of sheet metal). Volkswagen does not only apply lasers to welding, but also to brazing and cutting. In Volkswagen's Wolfsburg plant, for example, there are 150 4 kW Nd:YAG lasers (shown by trumpf data), a 1 kW Nd:YAG laser (shown by trumpf data), 250 laser welding Head, and 3 laser cutting heads. Although the advantages of Volkswagen's use of lasers are mainly reflected in the Wolfsburg plant, Loeffler said, but laser equipment is used throughout the group, whether they are in low-cost areas or in high-cost areas. Thus, you can see them in all regions from Belgium to South Africa.

The car is produced at a speed of 100 processes per hour. Undoubtedly, the normal operation of production is extremely important. However, Loeffler believes that this is no longer a problem and estimates that the normal operating rate has exceeded 99%. “Keep efficient and get time”. It should be noted that the equipment operators are neither scientists nor optical engineers, they are just ordinary people who have received equipment operation training. In an interview with operators about the importance of operational fluency, Loeffler said, “Workers must feel that they have these systems.” Although perhaps he said that it is not objective, he described laser processing as "the most reliable process in our factory," and said, "These technologies have been verified."

One of the great benefits of using a laser system for body welding is that the device is inherently powerful and flexible. For example, Volkswagen has developed a structural platform with 14 laser devices that can be used for both Golf soldering (5,340mm) and copper plating (3,400mm), as well as handling VW models from small to Lupo ("three liter" cars, so to speak It is because it consumes about three liters of fuel per 100km. It is as large as the Touareg SUV (in Porsche, Cayenne, laser welding is also used for Touareg chassis splicing). The structural platform requires 40% less floor area than similar spot welding equipment. In addition, Loeffler pointed out that it is also possible to use a platform's laser generator to provide loading/fixing/unloading work for similar platforms, thus making full use of processing equipment.

Configure the laser robot along the main production line. Loeffler said that as they standardize 4 kW YAG lasers, they also standardize the use of laser heads with fixtures (clamp types include: wheel clamps, two-wheel clamps, split wheel clamps, and single-finger and double Finger clamp). Again, it has the advantage of making it easy to process other products that are different from existing products. In addition, the product change time is also reduced to a minimum.

Another problem with automotive manufacturing is the problem of tolerance stacking. At this point, the Golf is the same as the other models. Loeffler said the problem has been solved, for example by using a component when installing the front bumper mounting plate, which can be optically measured to determine the size of the body, then the laser cuts the track long enough at the front end and then solders the mounting plate exactly in place. Go up. Loeffler described it as "the most amazing laser component", which is not to be overstated.

Although laser technology is not cheap, according to Loeffler's speculation, the expected investment can be recovered in four years. VW not only greatly increases the number of laser devices (currently has been added to 450 units, which is far ahead of other car manufacturers), and Loeffler's eyes have already been invested in the next generation of laser equipment. He is looking for a 6kw device with an efficiency of 20% and a beam quality of 6mm*mrad for flexible transmission in cable lengths up to 100m with uptime of 99.9% and repair time of no more than 30 minutes.

Loeffler mentioned by the way that he has been working on cutting and welding plastics for a long time. Perhaps, VW will see the welding scene of plastic materials in its own factory in the future.