Welding is widely used in machinery manufacturing, petrochemical, bridge, shipbuilding, construction, power engineering, traffic vehicles, aerospace and other departments, has become an indispensable processing in the machinery manufacturing industry. Moreover, with the development of the national economy, its application areas will continue to be widened.
Laser as a 20th century, following the atomic energy, computer, semiconductor, the human one of the major inventions, with its high energy density, high precision, adaptability and other characteristics, as a new method of cutting and welding used in industrial production, with Great potential for development. Laser welding in the industrial production to give full play to its advanced, fast and flexible processing characteristics, it is both industrial technology development of new technology assurance, but also indispensable technical means of high-quality, low-cost production .
Fiber laser has many advantages such as compact structure, modular design, maintenance-free, easy operation and system integration. It is widely used in laser cutting and laser welding applications.
The development background of laser welding
1) laser development. The initial Chinese name of the laser is called "laser", it is its transliteration of English name LASER , is taken from the acronym of each word of Light Amplification by Stimulated Emission of Radiation. Meaning "Light amplification by stimulated emission of radiation." In 1964 in accordance with the famous scientist Qian Xuesen proposed "light stimulated radiation" renamed "laser". The principle of laser as early as 1916 has been found by the famous American physicist Einstein, but the first successful manufacture until the 1960 . Laser come into being in the theoretical preparation and production practice in the context of the urgent needs, when it came out, it was an unusually rapid development, laser development not only make the ancient optical science and optical technology new, and led to The emergence of a whole emerging industry. Laser can make people effectively use the unprecedented advanced methods and means to get unprecedented benefits and results, thus contributing to the development of productive forces.
2) The development of welding lasers. As the laser has very good advantages, in the last 1970s, laser technology has begun to use in the field of welding, welding methods in the field of research, laser welding accounted for about 20%, only after gas shielded welding. Welding lasers require high power density (104 ~ 105W / cm2), power density distribution was based modal, beam quality is good. Commonly used welding laser mainly includes the following several kinds:
A) CO2 gas lasers
Gas lasers with CO2 gas as the working substance. Simple structure, low cost; easy to operate; uniform working medium, good beam quality; and can be more stable for a long time the continuous work. This is currently the most species, widely used type , laser helium - neon laser is the most commonly used one.
B) Nd: YAG lasers, disc YAG lasers
It is solid laser with yttrium aluminum garnet crystal as the substance, the chemical formula of yttrium aluminum garnet is Y3Al5O15, referred to as YAG.
C) fiber lasers
D) semiconductor lasers
3) the development of welding robots
The use of laser for welding robots is an important form of laser welding. Welding robot with multiple degrees of freedom, flexibility programming, high degree of automation, high degree of flexibility, is an important part of the welding production line. The welding of the laser is installed on the welding robot, which greatly improves the welding quality and the application range of the welding robot. The laser welding robot is becoming more and more important in the shipboard and automobile production line.
Principle and Technology of Laser Welding
Laser welding of metal materials, in essence, is the interaction of laser and non-transparent material process. This process is extremely complex, microscopic is a quantum process, the macro is the performance of reflection, absorption, melting, vaporization and so on. Laser welding can be used to achieve continuous or pulsed laser beam, the principle of laser welding can be divided into heat conduction welding and laser deep welding. Power density of less than 104 ~ 105 W / cm2 for the heat conduction welding, this time the depth of welding, welding speed is slow; power density greater than 105 ~ 107 W / cm2, the metal surface under the heat of the concave into a "hole" to form a deep welding, Welding speed, depth ratio of large features. Laser and the process of the workpiece will appear in the process of self-oscillation effect, the pool, the pool of small holes, metal flow phenomenon has cyclical changes. The frequency of this oscillation is related to the parameters of the laser beam, the thermophysical properties of the metal, and the dynamic characteristics of the metal vapor. The cyclical changes in the bath will produce two unique phenomena in the weld: one is filled with metal vapor pores, due to cyclical changes, while the molten pool of metal in its surrounding and forward along the flow, plus Metal evaporation caused by the disturbance, it is possible to cut off the small hole, so that the steam to stay in the weld, the formation of stomata after solidification, and the other is the weld root penetration of the cyclical changes, which is related to the cyclical changes in the hole.
Laser welding power density, pulse waveform, out of focus and welder speed and auxiliary hair is an important factor affecting the quality of laser welding, their organic coordination determines the quality of the final welding quality. Laser welding has many advantages over other traditional welding processes. One of its main advantages is the ability to concentrate the laser beam in a very small area, resulting in a high energy density heat source, which then rapidly sweeps through the seam to be welded. In this respect, the laser welding can be welded to the electron beam Compared with the close convergence of the laser beam, the effective transmission of heat to the workpiece and the small heat affected zone, it also brings the problem of the joint assembly. The small assembly deviation will lead to the change of the welding condition. A very narrow gap (≤ 0.1mm) can also cause laser radiation coupling defects and thermal efficiency reduction. In order to solve the high precision of laser welding joint assembly and high gap requirements, welds prone to pores, cracks and undergone and other defects and equipment investment, energy conversion rate of the shortcomings of laser welding in recent years, one of the trends is the laser composite technology The Such as laser + arc joint welding method, which focuses on the laser welding of the weld aspect ratio is large, the heat affected zone is small, welding speed, welding line energy is low, welding deformation is small, the focus of the spot after the small diameter and high energy density The advantages and investment of arc welding equipment are small, the gap is not clear, can fill the advantages of metal. Has achieved the effect of increasing the laser absorption rate, increasing the penetration depth and stabilizing the arc. Laser composite technology in addition to laser + arc, but also the development of laser - high frequency welding, laser welding and laser brazing and other comprehensive technology to broaden the scope of application of laser welding and the use of the effect, to promote the laser welding technology Further development.
Application of Laser Welding in Automobile Manufacturing
The development of the automobile industry put forward higher requirements for the quality of the vehicle body. Laser welding, cutting technology is not only in the processing quality is superior to traditional processing methods, and production efficiency has also been significantly improved. In the 21st century, laser welding, cutting technology in the field of automotive manufacturing will play a vital role. Laser welding in the automobile manufacturing in the entire process mainly includes three major types, namely: unequal thick plate laser welding; body assembly and sub-assembly of the laser welding; auto parts laser welding. The tailor-welded blanket was originally a technology used by Japanese Honda in the 1960s to make the interior panels of the car body. From the mid-1980s, the laser welding blanket was used as a new technology in Europe, the United States, Japan Has received widespread attention. Laser welding is in the body design and manufacturing, according to the different design and performance requirements of the body, different thickness, different materials, different or the same performance of the plate through the laser cutting and assembly technology connected into a whole, and then stamping into a body part. Laser deep welding technology with its high welding speed and excellent connection quality, greatly improving the laser welding technology in the field of manufacturing applications. Laser welding technology used in automobile body can greatly improve the rigidity, strength and sealing of the car; reduce the weight of the body and achieve the purpose of energy saving; improve the body assembly accuracy, the body stiffness increased by 30%, thereby enhancing the safety of the body; Reduce the amount of stamping and assembly in the car body manufacturing process, reduce the number of body parts and improve the degree of integration of the body; the whole body strength is higher, better security, and reduce the vehicle during the process of noise and vibration, improved Ride comfort. Auto parts welding using laser welding instead of traditional welding, parts welding parts almost no deformation, welding speed, and does not require post-weld heat treatment, the current laser welding widely used in transmission gear, valve tappet, door hinge, drive shaft, steering shaft , The engine exhaust pipe, clutch, supercharger axle and chassis and other auto parts manufacturing, as a standard auto parts manufacturing process.
Maxphotonics is the leading manufacturer and developer of laser, with laser components vertical integration capabilities, product coverage two categories :pulse laser, continuous laser. It has the advantage of high electro-optical conversion efficiency, good beam quality, compact structure, maintenance-free, laser output power has reached 6kW, can be used for stainless steel, carbon steel, aluminum, copper and other metal materials and non-metallic materials marking, cutting , Welding, drilling, in the sheet metal cutting, metal processing, home appliances manufacturing, automotive manufacturing and other fields widely used.
Nowadays ,Laser welding technology gradual replace arc welding, resistance welding and other traditional welding methods of the trend has been irreversible in the next century, the laser welding technology in the field of material connections will play a vital role.
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