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How to use laser welding machine,limitations of laser beam welding,how does fiber laser welding work,Laser welding machine is usually also called laser welding machine, energy negative feedback laser welding machine, laser welding machine, laser welding machine, laser cold welding machine, laser argon welding machine, laser welding equipment, etc.

The working principle of laser welding machine:

Laser welding uses high-energy laser pulses to locally heat the material in a small area. The energy of laser radiation diffuses into the material through thermal conduction, and the material melts to form a specific molten pool. It is a new type of welding method, mainly used for welding thin-walled materials and precision parts. It can achieve high aspect ratio, small weld width, small heat affected zone spot welding, butt welding, seam welding, sealing welding, etc. Small deformation, fast welding speed, smooth and beautiful welding seam, no need to handle or simple processing after welding, high welding seam quality, no porosity, precise control, small focus, high positioning accuracy, and easy to realize automation.

Which industries are suitable for the use of laser welding machines?

Products with welding requirements

Products that require welding seams are welded with laser welding equipment, which not only has small weld seams, but also does not require solder.

Highly automated products

In this case, the laser welding equipment can be manually programmed for welding, and the path is automatic.

Products at room temperature or under special conditions.

It can stop welding at room temperature or under special conditions, and the laser welding equipment is easy to install. For example, when laser light passes through an electromagnetic field, the beam does not deflect. The laser can be welded in vacuum, air and certain gas environments, and can pass through glass or materials that are transparent to the beam to stop welding.

Some inaccessible parts require laser welding equipment

It can weld hard-to-reach parts and realize non-contact remote welding with high sensitivity. Especially in recent years, under the condition that YAG laser and fiber laser technology are very mature, laser welding technology has achieved more general promotion and application.

How does the Laser Welder work?

Laser welding uses high-energy laser pulses to locally heat the material in a small area. The energy of the laser radiation diffuses into the material through heat conduction, and the material is melted to form a specific molten pool. It is a new type of welding method, mainly for the welding of thin-walled materials and precision parts. It can realize spot welding, butt welding, stitch welding, sealing welding, etc., with high aspect ratio, small weld width, and small heat affected zone. Small deformation, fast welding speed, smooth and beautiful welding seam, no need to handle or simple processing after welding, high welding seam quality, no porosity, precise control, small focus spot, high positioning accuracy, easy to realize automation.

The working principle of  laser welding machine: 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. The power density is less than 104~105 W/cm2 for heat conduction welding. At this time, the penetration depth is shallow and the welding speed is slow; when the power density is greater than 105~107 W/cm2, the metal surface is recessed into “holes” under the action of heat to form deep penetration welding. Features of fast welding speed and large aspect ratio.

The principle of thermal conduction laser welding is: laser radiation heats the surface to be processed, and the surface heat diffuses into the interior through thermal conduction. By controlling the laser pulse width, energy, peak power and repetition frequency and other laser parameters, the workpiece is melted to form a specific molten pool .

The laser welding machine used for gear welding and metallurgical sheet welding mainly involves laser deep penetration welding.

Laser deep penetration welding generally uses continuous laser beams to complete the connection of materials. The metallurgical physical process is very similar to electron beam welding, that is, the energy conversion mechanism is completed through the “key-hole” structure.

Under sufficiently high power density laser irradiation, the material will evaporate and form small holes. This steam-filled hole is like a black body, absorbing almost all of the incident beam energy. The equilibrium temperature in the cavity reaches about 2500 0C. The heat is transferred from the outer wall of the high-temperature cavity to melt the metal surrounding the cavity.

The small hole is filled with high-temperature steam generated by continuous evaporation of the wall material under the irradiation of the light beam. The four walls of the small hole are surrounded by molten metal, and the liquid metal is surrounded by solid materials (and in most conventional welding processes and laser conduction welding, the energy first Deposited on the surface of the workpiece, and then transported to the inside by transfer).

The flow of liquid outside the wall of the hole and the surface tension of the wall layer are maintained in a dynamic balance with the continuously generated steam pressure in the cavity. The light beam continuously enters the small hole, and the material outside the small hole is continuously flowing. As the beam moves, the small hole is always in a stable state of flow.

That is to say, the small hole and the molten metal surrounding the hole wall move forward with the forward speed of the leading light beam. The molten metal fills the gap left by the small hole and condenses, and the weld is formed.

And the above process happens very quickly, so the welding speed can easily reach several meters per minute.

Deep penetration welding principle of laser welding machine

The deep penetration welding of laser welding machine usually uses fiber continuous laser beam to complete the connection of materials. The metallurgical physical process is very similar to electron beam welding, that is to say, the energy conversion mechanism is completed through the “keyhole” structure. Under sufficiently high power density laser irradiation, the material evaporates and forms small holes. This steam-filled hole is like a black body, absorbing almost all of the incident beam energy.

The equilibrium temperature in the cavity reaches approximately 2500°C. Heat is transferred from the outer wall of the high temperature cavity to melt the metal around the cavity. The small holes are filled with high-temperature steam, which is produced by continuous evaporation of the wall material under the irradiation of the radiation beam. The four walls of the small hole are surrounded by molten metal, and the liquid metal is surrounded by solid materials (in most conventional welding processes and laser conduction welding, energy is first deposited on the surface of the workpiece and then transmitted to its surface).

The liquid flow outside the pore wall and the surface tension of the wall layer maintains a dynamic balance with the steam pressure continuously generated in the cavity. The light beam continuously enters the small hole, and the material outside the small hole flows continuously.

With the movement of the beam, the small hole is always in a stable flow state. In other words, the small hole and the molten metal surrounding the hole wall move forward at the forward speed of the guided beam, and the molten metal fills the gap left by the small hole and condenses to form a weld. All the above processes happen so fast that the welding speed can easily reach a few meters per minute.

The main process parameters of laser deep penetration welding

(1) Laser power. There is a laser energy density threshold in laser welding. Below this value, the penetration depth is very shallow. Once this value is reached or exceeded, the penetration depth will be greatly increased. Only when the laser power density on the workpiece exceeds the threshold (related to the material), will plasma be generated, which marks the progress of stable deep penetration welding. If the laser power is lower than the threshold, only surface melting of the workpiece occurs, that is, welding is performed with a stable thermal conductivity type.

When the laser power density is close to the critical condition for forming small holes, deep penetration welding and conduction welding will alternately become unstable welding processes, resulting in large fluctuations in penetration. In laser deep penetration welding, the laser power simultaneously controls the penetration depth and welding speed. Weld penetration is directly related to beam power density and is a function of incident beam power and beam focus. Generally speaking, for a laser beam with a certain diameter, the penetration depth increases as the beam power increases.

(2) Beam focus. The beam spot size is one of the most important variables in laser welding, because it determines the power density. But for high-power lasers, although there are many indirect measurement techniques, its measurement is still a difficult problem.

The beam focusing diffraction limit spot size can be calculated according to the light diffraction theory, but due to the aberration of the focusing lens, the actual spot size is larger than the calculated value. The simplest actual measurement method is the isothermal profile method, which uses thick paper to scorch and penetrate a polypropylene plate to measure the focal point and perforation diameter. This method should be practiced through measurement to master the laser power and beam action time.