Analysis of five laser welding processes in the field of industrial manufacturing
With the rapid development of the global manufacturing industry, welding technology has become more and more widely used, and the level of welding technology has become higher and higher. New welding process methods are constantly emerging, and professional welding equipment is changing with each passing day. At the same time, domestic and foreign welding equipment manufacturers have also demonstrated their strengths in various ways, especially through the exhibition to display a wide variety of products and advanced technologies. Since the development of carbon arc welding at the end of the century, it has only a history of more than 100 years, and hundreds of methods have been formed at present, and the level of welding technology has also reached a new height. Welded structures are developing in the direction of large size, complexity and high parameters.
Processing principle of laser welding technology
Laser radiation heats the surface to be processed, and the surface heat diffuses to the interior through thermal conduction. By controlling the laser parameters such as the width, energy, peak power and repetition frequency of the laser pulse, the workpiece is melted to form a specific molten pool.
Laser welding can be realized by continuous or pulsed laser beam. The principle of laser welding can be divided into heat conduction welding and laser deep penetration welding. When the power density is less than 10-10 W/cm, it is thermal conduction welding. At this time, the penetration depth is shallow and the welding speed is 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 penetration welding. The welding speed is fast and the aspect ratio is large.
Laser welding technology is widely used in high-precision manufacturing fields such as automobiles, ships, aircraft, and high-speed railways, which has brought a significant improvement to people's quality of life, and has led the home appliance industry into the era of precision work.
Especially after the 42-meter seamless welding technology created by Volkswagen, which greatly improved the integrity and stability of the body, Haier Group, a leading home appliance enterprise, grandly launched the first washing machine produced with laser seamless welding technology. People's lives have brought huge changes.
Processing principle of laser hybrid welding
Laser hybrid welding is the combination of laser beam welding and MIG welding technology to obtain the best welding effect, fast and weld bridging ability, and is the most advanced welding method at present.
The advantages of laser hybrid welding are: high speed, small thermal deformation, small heat affected area, and ensure the metal structure and mechanical properties of the weld. In addition to the welding of automotive sheet metal structures, laser hybrid welding is also suitable for many other applications. For example, this technology is applied to the production of concrete pumps and mobile crane jibs. These processes require the processing of high-strength steel. The traditional technology often leads to an increase in cost due to the need for other auxiliary processes such as preheating. Furthermore, the technology can also be applied to the manufacture of rail vehicles and conventional steel structures (such as bridges, fuel tanks, etc.).
Processing principle of friction stir welding
Friction stir welding uses friction heat and plastic deformation heat as welding heat sources. The welding process of friction stir welding is that a stirring needle of a cylinder or other shape (such as a threaded cylinder) is inserted into the joint of the workpiece, and the high-speed rotation of the welding head makes it rub against the welding workpiece material, so as to make the connection part The material softens as the temperature rises.
In friction stir welding, the workpiece should be rigidly fixed on the back pad during the welding process, the welding head rotates at a high speed, and the seam along the workpiece moves relative to the workpiece.
The protruding section of the welding head protrudes into the material for friction and stirring, and the shoulder of the welding head rubs against the surface of the workpiece to generate heat, and is used to prevent the overflow of the plastic material, and at the same time, it can remove the oxide film on the surface.
A keyhole is left in the terminal at the end of the friction stir weld. Usually this keyhole can be cut off, or it can be sealed by other welding methods.
Friction stir welding can realize welding between dissimilar materials, such as metals, ceramics, plastics, etc. Friction stir welding has high welding quality, is not easy to produce defects, easy to achieve mechanization, automation, stable quality, low cost and high efficiency.
Processing principle of electron beam welding
Electron beam welding is a welding method using the thermal energy generated by the accelerated and focused electron beam bombarding the weldment placed in vacuum or non-vacuum.
Electron beam welding is widely used in many industries such as aerospace, atomic energy, national defense and military industry, automobiles and electrical and electrical instruments because of its advantages of no electrode, not easy to oxidize, good process repeatability and small thermal deformation.
The electrons escape from the emitter (cathode) in the electron gun. Under the action of the accelerating voltage, the electrons are accelerated to 0.3 to 0.7 times the speed of light and have a certain kinetic energy. Through the action of the electrostatic lens and the electromagnetic lens in the electron gun, the electron beam current with high power density is converged. This electron beam hits the surface of the workpiece, and the kinetic energy of the electrons is converted into thermal energy to rapidly melt and evaporate the metal. Under the action of high-pressure metal vapor, a small hole is quickly "drilled" on the surface of the workpiece, also known as "keyhole". With the relative movement of the electron beam and the workpiece, the liquid metal flows around the small hole to the back of the molten pool. And cool and solidify to form a weld.
The electron beam penetration ability is strong, the power density is extremely high, the aspect ratio of the welding seam is large, which can reach 50:1, and the large thickness material can be formed at one time, and the maximum welding thickness can reach 300mm. The welding accessibility is good, the welding speed is fast, generally above 1m/min, the heat affected zone is small, the welding deformation is small, and the welding structure precision is high. The energy of the electron beam can be adjusted, and the thickness of the metal to be welded can be as thin as 0.05mm to as thick as 300mm, without grooves, one-time welding, which cannot be achieved by other welding methods. The range of materials that can be welded by electron beam is large, and it is especially suitable for the welding of active metals, refractory metals and workpieces with high quality requirements.
Processing principle of ultrasonic metal welding
Ultrasonic metal welding is a special method of joining the same metal or dissimilar metals by using the mechanical vibration energy of ultrasonic frequency. When the metal is ultrasonically welded, it neither transmits current to the workpiece nor applies a high temperature heat source to the workpiece, but under static pressure, the vibration energy of the frame is converted into friction work, deformation energy and limited temperature rise in the workplace. The metallurgical bond between the joints is a solid state welding that is achieved without melting the base metal. It effectively overcomes the phenomenon of spatter and oxidation caused by resistance welding, and the ultrasonic metal welding machine can perform single-point welding, multi-point welding and short strip welding of copper, silver, aluminum, nickel and other non-ferrous metal filaments or sheet materials shape welding. It can be widely used in the welding of thyristor leads, fuse pieces, electrical leads, lithium battery pole pieces and tabs.
Ultrasonic metal welding uses high-frequency vibration waves to transmit to the metal surface to be welded. Under pressure, the two metal surfaces are rubbed against each other to form fusion between the molecular layers. The advantages of ultrasonic metal welding are fast, energy saving, high fusion strength, good electrical conductivity, no sparks, and close to cold processing; the disadvantage is that the welded metal parts should not be too thick (generally less than or equal to 5mm), and the welding point should not be too large. pressurized.
Advantages, characteristics and application fields of laser welding, at present, there are more and more companies using mechanical welding machines in the market. Due to its unique advantages, it has been successfully used in the precision welding of micro and small parts. The emergence of high-power laser equipment has opened up a new field of laser welding. The deep penetration welding based on the pinhole effect has been obtained, and it has been widely used in machinery, automobile, steel and other industrial fields. Wuhan Jinmi Laser has been concentrating on the research and manufacture of advanced laser equipment for school teaching, providing industrial laser equipment with strong functionality and easy operation for the majority of students, and combining advanced technology at home and abroad to provide laser welding, cutting, Cladding and marking equipment.
