1. Laser welding
Laser welding: using laser radiation to heat the surface to be processed, surface heat through heat conduction to the internal diffusion, by controlling the laser pulse width, energy, peak power and repetition frequency and other laser parameters, so that the workpiece melting, forming a specific molten pool.
The principle of laser welding can be divided into: heat conduction welding and laser deep fusion welding.When the power density is less than 10~10 W/cm, the welding depth and welding speed are slow.When the power density is greater than 10~10 W/cm, the metal surface is concave into "holes" under the action of heat, forming deep fusion welding, which has the characteristics of fast welding speed and large ratio of depth to width.
Laser welding technology has been widely applied in the fields of high precision manufacturing such as automobiles, ships, aircraft and high-speed railways, which has brought great improvement to people's quality of life and led the home appliance industry to enter the era of Seiko.
Especially after the 42-meter seamless welding technology created by Volkswagen has greatly improved the integrity and stability of the car body, Haier Group, the leading enterprise of home appliances, solemnly launched the first washing machine produced by laser seamless welding technology. Advanced laser technology can bring great changes to people's lives.
2.Laser composite welding
Laser composite welding is the combination of laser beam welding and MIG welding technology to obtain the best welding effect, fast and weld bridging ability, is the most advanced welding method at present.
The advantages of laser composite welding are: fast speed, small thermal deformation, small heat affected area, and ensure the metal structure and mechanical properties of the weld.
Laser composite welding is suitable for many other applications besides the welding of automobile sheet structure parts.For example, the technology is used in the production of concrete pumps and mobile crane booms, which require processing of high-strength steel that would otherwise cost more because of the need for other auxiliary processes, such as preheating.
In addition, the technology can also be applied to the manufacture of rail vehicles and conventional steel structures (such as Bridges, fuel tanks, etc.).
3.fricition stir welding
Friction stir welding uses friction heat and plastic deformation heat as welding heat sources.Friction stir welding welding process is by a cylinder or other shapes (such as threaded cylinder) of the stirring needle extended into the joint of the workpiece, through the high-speed rotation of the welding head, so that it and the welding workpiece material friction, so that the material temperature of the connection part of the softening.
In the welding process of friction stir welding, the workpiece should be rigidly fixed on the back cushion, the welding head edge rotates at high speed, and the seam of the workpiece along the edge moves relative to the workpiece.
The protruding section of the welding head reaches into the material for friction and stirring. The shoulder of the welding head generates heat by friction with the surface of the workpiece, and is used to prevent the overflow of the material in the plastic state. At the same time, it can play the role of removing the oxide film on the surface.
A keyhole is left at the end of the friction stir weld. This keyhole can usually be removed or sealed by other welding methods.
Friction stir welding can realize the welding between dissimilar materials, such as metal, ceramic, plastic, etc.Friction stir welding welding quality is high, not easy to produce defects, easy to achieve mechanization, automation, stable quality, low cost and high efficiency.
4. Ultrasonic metal welding
Ultrasonic metal welding is a special method to connect the same metal or dissimilar metal by using mechanical vibration energy of ultrasonic frequency.
Metal in the ultrasonic welding, neither to the workpiece transmission current, nor to the workpiece with a high temperature heat source, just under static pressure, the frame vibration energy into the work of friction work, deformation energy and limited temperature rise.
Metallurgical bonding between joints is a kind of solid state welding without melting of the base metal.It effectively overcome the resistance welding spatter and oxidation and other phenomena, ultrasonic metal welding machine can copper, silver, aluminum, nickel and other non-ferrous metal wire or sheet material for single point welding, multi-point welding and short strip welding.
It can be widely used in the welding of SCR leads, fuse pieces, electrical leads, lithium battery pole pieces and pole ears.
The advantages of ultrasonic metal welding are: fast, energy saving, high fusion strength, good electrical conductivity, no spark, close to cold processing;
The disadvantage is that the welding metal parts can not be too thick (generally less than or equal to 5mm), welding spot can not be too large, need to be pressurized.
2021-04-09 
