Laser head technology
The application of laser head technology in the manufacturing industry is a topic of research in several countries.
With an increasing demand for high efficiency, environmental protection and automation in industrial development, the use of laser head technology is rapidly spreading in various fields of the manufacturing industry.
With this foundation, laser welding head technology is becoming a crucial aspect of laser head application.
Laser welding head is a significant part of the application of laser head processing technology and is considered the most promising welding head technology in the 21st century.
European and American countries have already fully integrated laser welding heads into industrial production since the end of the last century.
As industrial production continues to develop, efficient, flexible and environmentally friendly processing technologies will be increasingly favored.
The laser welding head utilizes a high-energy beam focusing mode, which enables deep penetration welding and rapid welding, among other ways that are difficult to achieve with traditional welding processes.
Furthermore, the laser welding head equipment is highly flexible and has mature online real-time detection technology, which enables high automation of mass production.
At present, many laser welding head production lines have been implemented in industrial production and have proven to be widely used in the processing industry.
In general, laser welding heads are capable of performing in the same applications as traditional welding heads, but with higher quality and faster processing efficiency.
Welding process using laser head technology
Laser head welding is a welding method that utilizes the radiant energy of the laser head.
The working principle involves exciting the active medium of the laser head, such as a mixture of CO 2 and other gases or a yttrium aluminum YAG garnet crystal, in a specific way to make it oscillate back and forth within the resonator. This produces a beam of excitation radiation.
When the beam comes into contact with the part, its energy is absorbed, causing the material's temperature to reach its melting point, making welding possible.
1. Laser welding head welding mode
Laser welding heads can be classified into two types: heat conduction welding heads and deep penetration welding heads.
Heat conduction welding heads diffuse heat into the workpiece through heat transfer, causing fusion to occur only at the welding surface. The interior of the workpiece is not fully penetrated and there is minimal vaporization. This type of welding head is mainly used for welding low-speed and thin-walled materials.
On the other hand, deep penetration welding heads not only completely melt the material but also cause it to evaporate, resulting in a large amount of plasma. The large amount of heat produced creates a keyhole at the front end of the weld pool.
Deep penetration welding heads are currently the most commonly used laser welding head welding method, as they are capable of fully welding the workpiece with a large input energy and fast welding speed.
2. Shape, structure and performance of laser welded heads
Due to the small focal spot produced by the laser head, the heat-affected zone during welding is significantly smaller compared to traditional welding methods. In most cases, laser welding does not require filler metal.
The welded surface must have a uniform and smooth appearance, with no visible pores or cracks. This makes laser welding ideal for applications where the appearance of the weld is a critical factor. Despite the small focal spot, laser welding is characterized by high laser beam energy density, generally ranging from 103-108 W/cm2.
During the welding process, the metal is rapidly heated and cooled, resulting in a large temperature gradient around the molten pool. This results in greater weld strength compared to the base metal, but with reduced plasticity.
To further improve weld quality, bifocal or composite welding head technologies can be used.
3. Advantages and disadvantages of laser welded heads
Its exclusive advantages:
(1) Laser welding results in high-quality weld strength with the ability to achieve a larger aspect ratio and faster welding speeds.
(2) Unlike traditional welding methods, laser welding does not require a vacuum environment, which allows for remote control and automation through the use of lenses and optical fibers.
(3) The laser head has a high power density, making it ideal for welding challenging materials such as titanium and quartz, and can effectively weld materials with different properties.
Of course, laser welded heads also have their disadvantages:
(1) The laser head and welding head system components are expensive, resulting in higher initial investment and maintenance cost compared with traditional welding methods, leading to lower economic benefits.
(2) The efficiency of the laser welding head is normally low, ranging from 5% to 30%, due to the low absorption rate of solid materials by the laser head, especially after plasma generation, as the plasma absorbs the laser .
(3) The small focus of the laser welding head demands high equipment precision and requires strict adherence to strict tolerances to minimize deviations and machining errors.
Conclusion
As the laser welding head becomes more widely used and commercially produced, the cost of laser head equipment has decreased significantly.
Additionally, the advancement of high-power laser heads and the development and implementation of new composite welding techniques have helped improve the previously low conversion efficiency of laser welding.
In the near future, laser welding heads are likely to gradually replace traditional welding methods such as arc welding and resistance welding and become the main industrial welding method.
