01 Laser welding
Laser welding: Laser radiation heats the surface to be processed, and the surface heat diffuses to the interior through thermal conduction. By controlling the width, energy, peak power and repetition frequency of the laser pulse, etc. The laser parameters melt the workpiece to form a specific molten pool.
▲ Spot weld and fix the welded parts
▲ Continuous laser welding
Laser welding can be achieved using continuous or pulsed laser beams. The principle of laser welding It 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 heat 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" due to heat, forming deep penetration welding, which has It has the characteristics of fast welding speed and large aspect ratio.
Laser welding technology is widely used in high-precision manufacturing fields such as automobiles, ships, aircraft, and high-speed rail. It has brought significant improvements 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 greatly improved the integrity and stability of the car body, Haier Group, a leading home appliance company, grandly launched the first washing machine produced with laser seamless welding technology , advanced laser technology can bring huge changes to people's lives.
02 Laser hybrid welding
Laser hybrid welding is a combination of laser beam welding and MIG welding technology to obtain the best welding effect, speed and weld bridging ability. It is currently the most advanced Welding method.
The advantages of laser hybrid welding are: fast speed, small thermal deformation, small heat-affected area, and ensuring the metal structure and mechanical properties of the weld.
03 Friction stir welding
Friction stir welding uses friction heat and plastic deformation heat as the welding heat source. The friction stir welding process involves a cylindrical or other shaped (such as a threaded cylinder) stirring needle extending into the joint of the workpiece. Through the high-speed rotation of the welding head, it rubs against the welding workpiece material, thereby making the connection part The material softens as the temperature increases.
During the welding process of friction stir welding, the workpiece must be rigidly fixed on the backing pad. The side of the welding head rotates at a high speed, and the edge of the workpiece moves relative to the seam of the workpiece.
The protruding section of the welding head extends into the material for friction and stirring. The shoulder of the welding head rubs against the surface of the workpiece to generate heat, and is used to prevent the overflow of plastic material and at the same time remove the surface oxide film. role.
The friction stir weld ends with a keyhole in the terminal. Usually the keyhole can be cut off or sealed using other welding methods.
Friction stir welding can achieve welding between dissimilar materials, such as metals, ceramics, plastics, etc.
Friction stir welding has high welding quality, is not prone to defects, is easy to implement mechanization, automation, stable quality, low cost and high efficiency.
04 Electron beam welding
Electron beam welding is a welding method that uses the heat energy generated by bombarding the weldment placed in a vacuum or non-vacuum with an accelerated and focused electron beam.
Electron beam welding is widely used in many industries such as aerospace, atomic energy, national defense and military industry, automobiles, and electrical and electrical instrumentation due to its advantages of not requiring welding rods, not easily oxidized, good process repeatability, and small thermal deformation. .
▲Principle of electron beam welding
Working principle of electron beam welding
Electrons escape from the emitter (cathode) in the electron gun. Under the action of accelerating voltage, Electrons are accelerated to 0.3 to 0.7 times the speed of light and have a certain kinetic energy. Then through the action of the electrostatic lens and the electromagnetic lens in the electron gun, the electron beam is converged into an electron beam with a high power density. This electron beam hits the surface of the workpiece, and the kinetic energy of the electrons is converted into heat energy, causing the metal to quickly melt and evaporate. Under the action of high-pressure metal vapor, a small hole is quickly "drilled" on the surface of the workpiece, also called a "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 cools and solidifies to form a weld.
▲Electron beam welding machine
Main features of electron beam welding
Electron beam has strong penetrating ability, extremely high power density, and large weld depth-to-width ratio , can reach 50:1, can achieve one-time forming of large thickness materials, 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 electron beam energy can be adjusted, and the thickness of the metal to be welded can be from as thin as 0.05mm to as thick as 300mm. It can be welded and formed in one go without beveling, which is unachievable 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.
05 Ultrasonic metal welding
Ultrasonic metal welding is a special method that uses mechanical vibration energy at ultrasonic frequencies to join similar metals or dissimilar metals. During ultrasonic welding of metal, neither current nor high-temperature heat is applied to the workpiece. Instead, the vibration energy of the frame is converted into friction work, deformation energy and limited temperature rise between the workpieces under static pressure. The metallurgical bond between joints is a solid-state welding without melting of the base metal.
It effectively overcomes the phenomena of spatter and oxidation produced during resistance welding. The ultrasonic metal welding machine can perform single-point welding of thin wires or sheet materials of non-ferrous metals such as copper, silver, aluminum, and nickel. , multi-point welding and short strip welding. It can be widely used in the welding of thyristor leads, fuse pieces, electrical appliance 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 rub against each other to form fusion between the molecular layers.
The advantages of ultrasonic metal welding are fast, energy-saving, high fusion strength, good conductivity, no sparks, and close to cold processing; the disadvantage is that the metal parts to be welded should not be too thick (generally less than or equal to 5mm), and the welding The spot cannot be too large and needs to be pressurized.
06 Flash butt welding
The principle of flash butt welding is to use a butt welding machine to make the metals at both ends come into contact, and pass a low voltage and strong current until the metal is heated to a certain temperature and becomes soft. Finally, axial pressure upsetting is performed to form a butt welded joint.
Before the two welding parts come into contact, they are clamped by two clamp electrodes and connected to the power supply. The movable clamp is moved. The end faces of the two welding parts are lightly contacted and energized and heated. The contact point is heated to form liquid metal. Blast, eject sparks to form a flash, continuously move the movable fixture, and flash continuously. Both ends of the weldment are heated. After reaching a certain temperature, the end faces of the two workpieces are squeezed, the welding power is cut off, and they are firmly welded together. The resistance heating of the weldment joint is used to cause the contact point to flash, melt the end metal of the weldment, and quickly apply top force to complete the welding.
Steel bar flash butt welding is to install two steel bars in a butt-jointed form, using the resistance heat generated by the welding current passing through the contact points of the two steel bars to melt the metal at the contact points, producing strong splashes, forming flashes, and accompanying A pressure welding method that has a pungent odor, releases trace molecules, and quickly applies upsetting force.