Laser head technology
The application of laser head technology in the manufacturing industry is the focus of research in various countries.
With the demand of industrial development for high efficiency, environmental protection and automation, the application of laser head technology is rapidly popularized in many fields of the manufacturing industry.
On this basis, laser welding head technology will become one of the important aspects of laser head application.
Laser welding head is an important part of the application of laser head processing technology. Welding head technology is also the most concerned and promising welding head technology in the 21st century.
As early as the end of the last century, European and American countries have fully applied laser-welded heads to industrial production.
With the development of industrial manufacturing, efficient, flexible and environmentally friendly processing technology will be favored.
Laser welding head adopts high-energy beam focusing mode, which can realize deep penetration welding, fast welding head and other forms that are difficult to realize in the welding process.
In particular, the laser welding head equipment is flexibly matched, and the real-time online detection technology is mature, which can realize the high automation of mass production.
At present, a large number of laser welding head production lines have been put into industrial production.
The practice has proved that laser-welded heads are widely used in the processing industry.
Basically, laser welded heads can be competent in the field where traditional welded head technology can be used, and have higher welded head quality and faster processing efficiency.
Welding process using laser head technology
Laser welding head is a process of effective welding by using the radiant energy of laser head.
Its working principle is to excite the active medium of the laser head in a specific way (such as the mixture of CO2 and other gases, YAG yttrium aluminum garnet crystal, etc.) to oscillate back and forth in the resonator, so as to form an excitation radiation beam.
When the beam contacts the workpiece, its energy is absorbed by the workpiece, and welding can be carried out when the temperature reaches the melting point of the material.
1. Laser welding head welding mode
Laser welded heads can be divided into heat conduction welded heads and deep penetration welded heads.
The heat of the former diffuses into the workpiece through heat transfer, and melting occurs only on the welding surface.
The interior of the workpiece is not completely penetrated, and there is basically no vaporization. It is mainly used for welding low-speed thin-walled materials.
The latter not only completely melts the material, but also evaporates the material to form a large amount of plasma.
Due to a large amount of heat, a keyhole will appear at the front end of the molten pool.
Deep penetration welding head is the most widely used laser welding head welding method at present, because it can completely weld the workpiece with large input energy and fast welding speed.
2. Shape, structure and performance of laser welded heads
Due to the small focus spot area produced by the laser head, the heat affected zone around the weld is much smaller than that of the ordinary welding head technology. Generally, laser welded heads do not need to be filled with metal.
The weld surface shall be continuous and uniform, with beautiful appearance, without surface defects such as pores and cracks.
It is very suitable for occasions with strict requirements on weld appearance. Although the focus area is relatively small, the energy density of the laser beam is very high (usually up to 103-108 w/cm2).
In the welding process, the metal is heated and cooled very quickly, and the temperature gradient around the molten pool is relatively large, which makes the head strength higher than the base metal, while the head plasticity is relatively low.
At present, the head quality can be improved by bifocal technology or composite welding head technology.
3. Advantages and disadvantages of laser welded heads
Its unique advantages:
(1) Laser welded heads can obtain high-quality head strength, larger aspect ratio and faster welding speed.
(2) Because the laser welding head does not need vacuum environment, it can realize remote control and automatic production through lens and optical fiber.
(3) The laser head has high power density and good welding effect on difficult welding materials such as titanium and quartz, and can weld materials with different properties.
Of course, laser welded heads also have their disadvantages:
(1) The accessories of the laser head and welding head system are expensive, so the initial investment and maintenance cost is higher than that of the traditional welding process, and the economic benefit is poor.
(2) The conversion efficiency of laser welding head welding is generally low (usually 5% ~ 30%), because the absorption rate of solid materials to laser head is low, especially after plasma is generated (plasma absorbs laser).
(3) Due to the small focus of laser welding head, the workpiece head requires high equipment accuracy, small equipment deviation and large machining error.
With the popularization and application of laser welding head and the commercial production of laser head, the price of laser head equipment decreases sharply.
However, the development of high-power laser head and the development and application of new composite welding methods also improve the low conversion efficiency of laser welding.
I believe that in the near future, laser welded heads will gradually replace the traditional welding processes (such as arc welding and resistance welding) and become the main method of industrial welding.