Laser welding machine, also known as laser welding machine and laser welding machine, is used for laser material processing. According to its working mode, it can often be divided into laser mold welding machine (manual laser welding equipment), automatic laser welding machine, jewelry laser welding machine, laser spot welding machine, fiber transmission laser welding machine, galvanometer welding machine, hand-held welding machine, etc. Special laser welding equipment includes sensor welding machine, silicon steel sheet laser welding equipment, keyboard laser welding equipment.

1. Laser welding machine

The workpiece of the laser welding machine quickly melts and even vaporizes after absorbing the laser. The molten metal forms a small hole laser beam under the action of steam pressure, which can directly illuminate the hole bottom, making the hole continuously extend until the steam pressure in the hole is balanced with the surface tension and gravity of the liquid metal. This welding mode has a large penetration and a large depth to width ratio. When the keyhole moves along the welding direction with the laser beam, the molten metal in front of the keyhole of the laser welding machine bypasses the keyhole and flows to the rear, forming a weld after solidification.

2. Understand the parameter settings of the laser welding machine

1) Laser power density

Power density is one of the most important parameters in laser processing. With higher power density, it can heat the surface layer to the boiling point in microseconds, thus generating a large amount of vaporization. Therefore, high power density is conducive to material removal processing, such as stamping, cutting and engraving. For lower power densities, it takes several milliseconds for the surface temperature to reach the boiling point. Before the surface layer vaporizes, the bottom layer reaches the melting point, which is easy to form good fusion welding. Therefore, in conductive laser welding, the power density is in the range of 104~106W/cm2. Beam spot size is one of the most important variables in laser welding, because it determines the power density.

2) Material absorption value

The absorption of laser by materials depends on some important properties of materials, such as absorptivity, reflectivity, thermal conductivity, melting temperature, evaporation temperature, etc., of which the most important is absorptivity.

The factors that affect the absorption of materials to laser beams include two aspects: one is the resistivity of materials. After measuring the absorptivity of the polished surface of the material, it is found that the absorptivity of the material is proportional to the square root of the resistivity, and the resistivity changes with temperature. And change; Secondly, the surface state (or finish) of the material has a more important influence on the light beam absorptivity, and has a significant impact on the welding effect. Non metals such as ceramics, glass, rubber and plastics have high absorption at room temperature, while metal materials have poor absorption at room temperature until the materials melt or even deflate. Its absorption will only increase dramatically. The method of using surface coating or forming oxide film on the surface is very effective for improving the absorption of light beam by materials.

3) Pulse shape and width

Pulse waveform is an important problem in welding, especially for thin plate welding. When the high intensity beam hits the material surface, part of the energy on the metal surface will be lost by reflection, and the reflectivity will change with the surface temperature. During the pulse action, the reflectivity of the metal varies greatly.

Pulse width is one of the important parameters of pulse welding. It is not only an important parameter different from material removal and material melting, but also a key parameter determining the cost and volume of processing equipment.

4) Effect of defocus

Due to the high power density of the spot center at the laser focus, it is easy to evaporate into holes. In each plane far from the laser focus, the power density distribution is relatively uniform. There are two defocusing methods: positive defocusing and negative defocusing. If the focal plane is above the workpiece, it is positive defocusing, otherwise it is negative defocusing. According to the geometrical optics theory, when the distance between the positive and negative defocusing planes and the welding plane is equal, the power density on the corresponding plane is approximately the same, but the actual shape of the weld pool obtained is different. When the defocusing is negative, greater penetration depth can be obtained, which is related to the formation process of the molten pool.

5) Parameter reference of HGTECH's handheld laser welding machine

3. Operation steps of laser welding machine

The operation specification of the laser welding machine is very important. If you do not operate according to the specification, you may not be able to start the machine, or the machine may be damaged. Therefore, you must use the laser welding machine according to the operation specification.

1) The preparation and inspection before starting the laser welding machine are essential:

a) Check whether the power connection of the laser welding machine is intact and whether the water circulation is normal;

b) Check whether the air circuit connection of the equipment in the machine is normal;

c) Check that the machine surface is free of dust, spots, oil stains, etc.

d) Before starting the machine, first turn on the power of motion control parts such as the automatic workbench, check whether each part operates normally, and then turn on the computer under normal conditions.

2) Power on

a) Turn on the power, turn on the water cooler and the laser generator in turn;

b) During operation, consider whether to add welding wire according to the situation of the workpiece.

c) The welding requirements and welding parameters are different for different workpiece materials.

d) The laser welding machine must be protected by argon to prevent the oxidation of the finished welding parts, and the workpiece welded is relatively beautiful.

e) Parameters that can be set for laser welding machine power supply: current 50-400A, 0.1-20MS; frequency 0-50. Normal welding workpiece simulation parameters are as follows: current: 90-120; pulse width: 4-6; frequency is 5-10; and the welding parameters are adjusted according to the material and actual conditions of the workpiece.

f) When the workpiece and parameters have been adjusted. Welding can be carried out when the welding focal length is ready. The laser welding machine uses the switch signal to control the laser output.

3) At the end of use, check the equipment and turn it off

a) After use, close the dust remover, water cooler, argon cylinder valve and other equipment in sequence;

b) Turn off the power switch and check whether the switch that needs to be turned off is turned off

4. Precautions for laser welding machine operation

1) During the operation of the laser welding machine, in case of emergency (water leakage, abnormal sound from the laser, etc.), press the emergency stop immediately and cut off the power quickly;

2) The external circulating water switch of laser welding must be turned on before operation;

3) Since the laser system is cooled by water and the laser power supply is cooled by air, it is strictly forbidden to start the machine if the cooling system fails;

4) Do not dismantle any parts in the machine at will, do not weld when the safety door of the machine is open, do not look directly at the laser or reflect the laser with your eyes when the laser is working, and do not face the laser welding head with your eyes to avoid eye injury;

5) Flammable and explosive materials shall not be placed on the laser path or the place where the laser beam can reach, so as to avoid fire and explosion;

6) When the machine is working, the circuit is in the state of high voltage and strong current. It is strictly forbidden to touch the circuit components in the machine during work;

5. Use the laser welding machine safely

When operating the laser welding equipment, the operator should pay attention to its operation process and procedures, and be able to debug in a specific way. Special requirements for materials or differences in welding processes may lead to abnormal operation of equipment. Only in this way can the laser welding machine maintain a good processing effect and bring us efficient and standardized production.

About HGTECH: HGTECH is the pioneer and leader of laser industrial application in China, and the authoritative provider of global laser processing solutions. We have comprehensively arranged laser intelligent equipment, measurement and automation production lines, and smart factory construction to provide overall solutions for intelligent manufacturing.