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Application of laser welding in the automotive industry

The successful demonstration of the world’s first laser was more than 40 years ago. Today, laser science and technology are booming, and its role far exceeds the original expectations of people in the early days of its invention. The application of laser technology currently covers many fields of science and technology, economy, military and society.The automotive industry is an important application field of laser processing, accounting for 15% of the share of laser processing. Laser welding, laser cutting, laser marking, and laser punching are all widely used.
1.Technical feasibility of laser welding
The most basic characteristics of laser (stimulated radiated light) are: monochromatism, directivity, and correlation. These unique properties, coupled with the resulting ultra-high brightness, ultra-short pulses and other properties, make it tightly integrated with modern industry. These characteristics are very suitable for welding processing.Lasers are generally classified according to the different working substances that produce lasers. There are mainly semiconductor (GaAs, InP, etc.) lasers, solid (Nd:YAG, etc.) lasers, gas (CO2, He-Ne, etc.) lasers, liquid (tunable dyes, etc.) lasers, chemical lasers, free electron lasers, etc.Among them, gas lasers use gas or metal vapor as luminous particles. It is currently the most diverse type, the most diverse excitation method, the broadest laser wavelength distribution area, easy to achieve high-power continuous output, and the most widely used class of lasers.A solid-state laser dumps the particles that produce the laser into a solid matrix, and its concentration is larger than that of a gas, so it can obtain a relatively large laser energy output. It has the characteristics of high energy, high peak power, compact mechanism, and durability.Lasers of these two stimulated substances are mainly used in laser welding.
The application of laser welding technology in the manufacturing field has steadily increased, from pulse to continuous, from low-power to high-power, from thin plates to thick parts, from simple single seams to complex shapes, laser welding has gradually become a mature modern processing technology in the process of continuous evolution. Technology.Laser welding is divided into pulsed laser welding and continuous laser welding. In continuous welding, it can be divided into heat conduction welding and deep penetration welding.With the increase of laser output power, especially the emergence of high-power CO2 lasers, laser deep penetration technology has developed rapidly at home and abroad. The largest welding aspect ratio has reached 12:1. Laser welding materials have also developed from general low-carbon steel to today’s welding galvanized sheet, aluminum sheet, titanium sheet, copper sheet and ceramic materials. The laser welding speed has also reached tens of meters per minute. Laser welding technology is becoming more and more mature, and it is widely used in production lines, such as gear welding, high-speed welding of automobile floor plates and structural parts (including car doors and bodies) on automobile production lines, and has achieved great results. Economic and social benefits.
According to relevant statistics, in developed industrial countries in Europe and the United States, 50%-70% of auto parts are processed by laser.Among them, laser welding is mainly used and cutting is mainly used. Laser welding has become a standard process in the automotive industry.The laser is used for the welding of body panels to weld metal plates of different thicknesses and different surface coatings together, and then press them. The panel structure made in this way can achieve the most reasonable metal combination.The speed of laser welding is about 4.5m/min, and there is little deformation, eliminating the need for secondary processing.Laser welding accelerates the process of replacing forged parts with stamped parts.The use of laser welding can reduce the lap width and some reinforcing parts, and can also compress the volume of the body structure itself.This alone can reduce the weight of the body by 56kg.Laser welding is used for welding the roof shell and frame, and the welding of the transmission converter cover, which is controlled by CNC. The cycle time is about 16 seconds, and the actual welding time is only 3 seconds. It can run continuously for 24 hours a day.Used for welding the gearbox assembly and chassis of a small car, the laser beam has a fast welding speed, is easy to automate and control, and is easy to merge into a flexible manufacturing system. The laser beam improves the manufacturer’s product design and production cycle and reduces the scrap rate of finished products.
2.Application of laser welding in the automotive industry
The use of laser welding can bring huge economic benefits to the automobile manufacturing industry. For example, a large number of spot welding in body assembly, the two welding heads are sandwiched on the edge of the workpiece for welding, the flange width needs to be 16mm, while laser welding is unilateral welding, only 5mm is required. If the spot welding is laser welding, each car can save 40kg of steel.Traditional spot welding is used to weld two pieces of 0.8mm steel plate stamping parts, the average is 20 points/min, the welding distance is 25mm, that is, the speed is 0.5m/min, and the laser welding speed can reach more than 5m/min.The use of laser welding technology not only reduces costs, but also greatly improves production efficiency.
At present, a kilowatt laser processing robot system costs only a few hundred thousand dollars, and the safety and reliability of the new laser are also guaranteed. The failure and shutdown rate is only 2%, and the protective measures are extremely reliable.When laser welding, the contact surface of the workpiece needs to be closely matched, which is not easy to achieve in terms of technology, but the current advanced clamping method and flange design suitable for laser welding have solved this problem. The gradual maturity of laser welding technology has led major automobile manufacturers to apply laser welding to automobile production lines without exception.
The United States was the first to introduce high-power lasers into the automotive industry. There are more than 40 laser processing stations in the Detroit area, the center of the U.S. automotive industry, which are used for cutting automotive metal parts and welding gears, shortening the modification of automobiles from 5 years to 2 years.
The United States General Motors Company has adopted 22 laser processing production lines, and the United States Ford Motor Company uses Nd:YAG lasers combined with industrial robots to weld car bodies, which greatly reduces manufacturing costs. In 2000, 50% of the resistance spot welding production lines of the three major automobile companies in the United States were replaced by laser welding production lines.In Japan, the successful application of laser welding on production lines has attracted the attention of the world. For example, the new method of laser welding and stamping thin steel plates in the manufacture of automobile bodies has now been imitated by most automobile manufacturers in the world.Many famous automobile companies in the world have built special production lines for laser welding: Thyssen Steel’s car floor welding production line, Volkswagen’s gear laser processing production line, and Mercedes-Benz’s 18 factories. Laser processing equipment is installed in 8 of the 18 factories.
In the automotive industry, laser welding is mainly used in the welding of automobile bodies and the welding of splicing blanks.In order to meet the needs of the market and customers, it is necessary to improve the body and manufacturing technology, and the body value of the car accounts for about 1/5 of the total value of the car. The laser welding process is used to make the impact resistance and fatigue resistance of the body can be significantly improved, and the quality of the car can be improved.Due to the use of computer control, laser welding has strong flexibility and mobility. It can weld special-shaped door panels, baffles, gears, instrument panels and other parts, and can also complete the assembly of roof and side surrounds, engine racks and radiator racks. If you add optical fiber transmission systems and manipulators, you can realize automated automobile assembly production lines.Using ND:YAG continuous lasers transmitted by optical fibers of about 3KW, combined with the spot welding system and the fixture on the production line, the purpose of automated welding can be achieved. General Motors, Mercedes-Benz, etc. have adopted this system and applied it to the production lines of the latest models. The laser welding system can almost meet the requirements of perfect processing, and it has excellent performance in efficiency, economy, safety, strength, and corrosion resistance.
The body and chassis of a car are composed of more than 300 kinds of parts. Laser welding can weld almost all materials regardless of thickness, grade, type, and grade together to make parts of various shapes, greatly improving the flexibility of automobile design.Splicing blanks is to optimize the component design on the basis of fully analyzing the body structure, so that it can be welded from a few typical blanks, which greatly reduces the number of molds and increases the material utilization rate, and can be used in parts with different strength requirements. Blanks of different thicknesses can be stamped and formed at once, which reduces weight and improves accuracy. It also greatly improves corrosion resistance and safety performance, and the body structure is also greatly simplified.Toyota’s side circumference production line adopts splicing slab welding technology, which reduces the number of molds to four, and the material utilization rate reaches 65%. Together with other components, the cost of each car is reduced by more than 30 U.S. dollars, greatly increasing the benefits of automobile manufacturers.
3.Prospects of laser welding technology
Laser welding technology has had an impactful impact on the traditional automobile welding process. Major automobile companies have a very positive attitude towards this. The adoption of new technologies means stronger competitiveness, especially in the fiercely competitive automobile industry.Laser welding technology has the greatest future in welding aluminum materials, replacing castings with welded parts, and welding the whole body frame structure. Laser manufacturers should seize business opportunities and work hard on the mobility and volume of lasers to transmit lasers with optical fibers to make lasers more suitable for the needs of automotive production lines.Some domestic laser product manufacturers have gradually realized this. For example, the pulsed Nd:YAG laser welding machine produced by Hubei Guangtong Photoelectric System Co., Ltd. uses optical fiber coupling to focus, which is easy to use. The laser head can be far away from the welding area. The laser performance is stable and reliable, and the life is long. Traditional optical traditional systems can also be used. The laser can be used for laser welding, laser cutting and punching. One machine is multi-purpose, especially suitable for laser processing workshops and automated production lines.
In the 21st century, the automotive industry is entering a way that can carry out flexible modular production according to user requirements. Traditional processing techniques cannot meet the needs of new production methods. This provides an opportunity for the large-scale application of laser welding technology. Laser welding technology and other laser processing technologies will definitely have greater development in the automotive field and become an important processing method in the automotive industry.

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