Laser Welding Machine in the Automotive Industry

More than four decades back, lasers came into existence and demonstrated powerful capabilities that thrilled the world. After so many years of development, laser technology has penetrated into various fields and played a vital role. In the automotive industry, laser technology is even more unique, laser welding, laser drilling, laser marking are widely used.

1. Definition of laser technology
Laser is a new light source in the 1960s. With good monochromaticity, strong directionality, high brightness and other characteristics. Thousands of laser working substances have been discovered, with wavelengths ranging from soft X-rays to the far infrared. Laser technology uses polarizing mirrors to reflect the beam produced by the laser so that it is concentrated in a focusing device to produce a beam of enormous energy. If the focal point is close to the workpiece, the workhorse melts and evaporates within milliseconds, an effect that can be used in the welding process.

2. Feasibility of laser welding technology
Lasers are generally categorized according to the different working substances that produce laser light, mainly semiconductor (GaAs, InP, etc.) lasers, solid-state (Nd: YAG, etc.) lasers, gas (CO2, He-Ne, etc.) lasers, liquid (tunable dyes, etc.) lasers, chemical lasers, free-electron lasers and so on. Among them, gas lasers use gas or metal vapors as light-emitting particles, and it is the class of lasers with the most varieties, the most diversified excitation modes, the widest laser wavelength distribution region, the easiest way to realize high-power continuous output, and the most widely used. Solid-state laser is to produce laser particles doped in the solid matrix, the concentration of which is larger than the gas, and thus can obtain a relatively large laser energy output, with large energy, high peak power, compact, solid and durable and so on. Laser welding in the main on the use of these two excited material laser.

The application of laser welding technology in the manufacturing field has been growing steadily, from pulse to continuous, from low power to high power, from thin plate to thick parts, from simple single seam to complex shapes, laser welding in the continuous evolution process has gradually become a mature modern processing technology. Laser welding is divided into pulsed laser welding and continuous laser welding, and in continuous welding can be divided into heat conduction welding and deep penetration welding. With the improvement of laser output power, especially the emergence of high-power CO2 laser, laser deep penetration technology at home and abroad have been rapid development, the largest welding depth-to-width ratio has reached 12:1, laser welding materials from the general development of mild steel to today's welding of galvanized sheet, aluminum, titanium, copper and ceramic materials, laser welding speed has reached dozens of meters per minute, the laser welding technology Increasingly mature, and a large number of applications to the production line in the automotive production line, such as gear welding, automotive floor and structural components (including the door body) of the high-speed welding and has achieved great economic and social benefits.

According to relevant statistics, in Europe and the United States developed industrial countries, there are 50% -70% of the auto parts are completed with laser processing. Which is mainly laser welding and cutting-based, laser welding in the automotive industry has become a standard process. Laser welding for body panels can be different thickness and have different surface coating layer of the metal plate welded together, and then stamping, so that the panel structure can be made to achieve the most reasonable combination of metal. The speed of laser welding is about 4.5m/min, and there is little deformation, eliminating secondary processing. Laser welding accelerates the process of replacing forged parts with stamped parts. The use of laser welding reduces the lap width and some of the reinforcing parts, and also compresses the volume of the structural parts of the bodywork itself. This alone reduces the weight of the body by 56 kg. laser welding is used for welding roof shells and frames, and for welding transmission converter covers, which are CNC-controlled, with a cycle time of about 16 seconds, and an actual welding time of only 3 seconds, and which can be operated continuously for 24 hours a day. Used to weld the small car transmission assembly and chassis, laser beam welding speed, easy to automate and easy to control and merge into a flexible manufacturing system, laser beam to improve the manufacturer's product design and production cycle, reducing the scrap rate of finished products.

3. Laser welding machine in the automotive industry
The use of laser welding can bring great economic benefits to the automobile manufacturing industry, such as body assembly in a large number of spot welding, the two welding head clamped on the edge of the workpiece welding, flange width needs 16mm, and laser welding is a one-sided welding, only 5mm, the spot welding for the laser welding, each car can save 40kg of steel. with the traditional spot welding welding two pieces of 0.8mm sheet steel stamping parts, the average is 20 points / min, welding distance is 25mm, that is, the speed of 0.5m / min, with laser welding speed can reach 5m / min or more. The use of laser welding technology, not only to reduce costs, but also greatly improve production efficiency. At present, a set of kilowatt-class laser processing robot system as long as hundreds of thousands of dollars, the safety and reliability of the new laser is also guaranteed, its failure downtime rate of only 2%, the protection measures are also extremely reliable. Laser welding requires a close match between the workpiece contact surface, which is not easy to realize in the process, but the current advanced clamping methods and suitable for laser welding flange design so that this problem has been solved, the gradual maturation of laser welding technology makes the major automobile manufacturers without exception will be applied to the laser welding of the automobile production line.

The United States is the earliest high-power lasers introduced into the automobile industry, in the United States automobile industry center in the Detroit area there are more than 40 laser processing station for automobile metal parts cutting and gear welding, so that the car's reformation from 5 years shortened to 2 years. The United States General Motors has adopted 22 laser processing production line, the United States Ford Motor Company using Nd: YAG laser combined with industrial robots to weld the sedan body, greatly reducing the manufacturing cost, the three major U.S. automobile companies in 2000, there have been 50% of the resistance spot welding production line was replaced by laser welding production line. In Japan, the successful application of laser welding in the production line for the world's attention, such as in the automobile body manufacturing in the implementation of laser welding of thin steel plate stamping molding of new methods, and now has been most of the world's automobile manufacturers to follow suit. Many of the world's leading automobile companies have built a special laser welding production line: Thyssen Steel car floor welding production line, Volkswagen automobile factory gear laser processing production line, Mercedes-Benz automobile factory in the 18 plant in 8 plant installed laser processing equipment.

Laser welding machine is used in the automotive industry most notably for the welding of car bodies and the welding of spliced blanks. In order to meet the market and customer demand, improve the body and manufacturing process is very necessary, and the value of the car's body of about 1/5 of the total value of the car, the use of laser welding process so that the body of the impact resistance and fatigue resistance can be significantly improved, improve the quality of the car. Laser welding due to the use of computer control, so it has a strong flexibility and mobility, can be a special shape of the door panels, fenders, gears, instrument panels and other parts of the welding, but also to complete the roof and side of the car, the engine frame and the radiator frame and other parts of the assembly, if coupled with fiber optic transmission system and robotic hand, you can realize the automated automotive assembly line. The use of about 3KW fiber optic transmission Nd: YAG continuous laser, with spot welding system, and production line fixtures, can achieve the purpose of automated welding, General Motors, Mercedes-Benz, etc. have adopted this system used in the production line of the latest models, the laser welding system can almost achieve the requirements of perfect processing, in terms of efficiency, economy, safety, strength, corrosion resistance have excellent performance. The laser welding system is used in the production line of the latest car models.

A car body and chassis consists of more than 300 kinds of parts, the use of laser welding can be almost all regardless of the thickness, grade, type, grade of materials welded together to make a variety of shapes of parts, greatly improving the flexibility of automobile design. Splicing billet is in the full analysis of the body structure on the basis of optimizing the design of components, so that it can be a few typical billet welding from a few kinds of billet, which greatly reduces the number of molds, increasing the utilization of materials, but also in the strength of the different requirements of different parts of the billet of different thicknesses can be used in a stamping molding to reduce the weight and improve the accuracy, but also make the corrosion resistance and safety performance have been greatly improved! The body structure is also greatly simplified. Toyota's side enclosure production line uses a splicing blank welding technology, making the number of molds down to four, the material utilization rate of 65%, plus other parts, so that the cost of each car down more than 30 U.S. dollars, greatly increasing the benefits of automobile manufacturers.

At present, in foreign countries, Germany Volkswagen in AudiA6, GolfA4, Passat and other brands of the roof are laser welding, BMW, General Motors in the top of the frame is also using laser welding, General Motors, Toyota, Ford, BMW, Fiat, Mercedes-Benz, Volkswagen are used in the laser splicing plate technology, the United States Big Three, Germany Mercedes-Benz is using a laser welded transmission components. Volkswagen, General Motors, Mercedes-Benz, Nissan applied laser cutting technology, Fiat and Toyota with laser coating engine exhaust valves, Volkswagen engine camshafts to achieve laser surface hardening treatment.

In the country, from domestic high-quality models, such as: Passat, Buick, Audi, etc. are used to laser welding to laser welding on the transformation of the domestic began to use laser welding technology, the first in the country to use laser welding technology (rather than laser welding), in the forefront of the FAW-Volkswagen, while some of the domestic automobile manufacturers have gradually begun to use this technology. Laser technology is currently in the application of FAW, FAW Volkswagen AudiA6 top and BORA back cover using laser welding, Sagitar (Sagitar) were in the top of the body, back cover and other parts of the laser welding technology, welding length of more than 30 meters. FAW used equipment for the German HassYAG 3KW laser and Kuka robot, FAW Car Company sedan body cladding parts using laser cutting, using equipment for the German ARNOLD 3KW three-dimensional five-axis CO2 laser processing machine, FAW chassis parts plant brake shoe using laser hardening, using equipment for the domestic 2KW CO2 laser processing machine, FAW mold center thin plate parts for the Laser cutting, the use of equipment for the domestic 1.5KWCO2 laser processing machine. With the maturity of laser welding technology and laser welding machine price drop, China's Chery Automobile also began to use laser welding technology.

4. Prospects of laser technology

Laser welding technology on the traditional automotive welding process has brought the impact of the major automotive companies have a very positive attitude towards this, the use of new technologies means stronger competitiveness, especially the brutal competition in the automotive industry. Laser welding technology in the welding of aluminum, welded parts instead of castings and full-body frame structure welding application of the biggest future, laser manufacturers should seize the business opportunities in the laser's mobility, volume and other aspects of the work, with fiber optic transmission laser, so that the laser is more suitable for automotive production line needs. Some domestic manufacturers of laser products have gradually realized this, such as Hubei Optical Optical Systems Co., Ltd. production of pulsed Nd: YAG laser welding machine using optical fiber coupling focusing, easy to use, the laser head can be far away from the welding zone, laser performance is stable and reliable, long life, but also the use of the traditional optical traditional system, the laser can be laser welding, laser cutting and punching, both. One machine multi-purpose, especially suitable for laser processing workshop and automated production line.

5. Summary

The 21st century automobile industry is stepping into the user's requirements in accordance with the flexible modular production mode, the traditional processing technology can not meet the needs of the new production mode, which gives the large-scale application of laser welding technology provides an opportunity, laser welding technology and other laser processing technology in the automotive field will have a greater development, become an important processing method in the automotive industry.