How to use laser welding machine?

How to use laser welding machine?

At this stage, the manufacturing, automotive and eyewear industries all have some demand for laser welding machines. How much do you know about the common technical parameter debugging, operating direction and flow of the laser welding machine in use?

First of all, we understand the main parameters of the laser welding machine

1. Laser power density

Power density is one of the most critical parameters in laser processing. With a higher power density, the surface layer can be heated to the boiling point within a microsecond time range, thereby generating a large amount of vaporization. Therefore, the high power density facilitates material removal processes such as stamping, cutting and engraving. For lower power densities, it takes a few milliseconds for the surface temperature to reach the boiling point. Before the surface layer is vaporized, the bottom layer reaches its melting point, which makes it easy to form a good fusion weld. Therefore, in conductive laser welding, the power density is in the range of 104~106W/cm2.

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, its measurement is a difficult problem, although there are many indirect measurement techniques.

2. Material absorption value

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

The factors that affect the absorption rate of the laser beam include two aspects: one is the resistivity of the material. 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 beam absorption rate, and has a significant influence on the welding effect.

The output wavelength of CO2 laser is usually 10.6μm. Non-metals such as ceramics, glass, rubber, plastics, etc. have a high absorption rate at room temperature, while metal materials have a poor absorption rate at room temperature until the material is melted or even outgassed. Its absorption will only increase dramatically. The method of using a surface coating or generating an oxide film on the surface is very effective for improving the absorption of the light beam by the material.

3. Pulse shape and width

Pulse waveform is an important issue in welding, especially for thin plate welding. When a high-intensity beam hits the surface of the material, part of the energy on the metal surface will be lost by reflection, and the reflectivity will vary with the surface temperature. During the pulse action, the reflectivity of the metal changes 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 that determines the cost and volume of processing equipment.

4. The effect of defocusing

Because the power density in the center of the spot at the laser focal point is too high, it is easy to evaporate into a hole. On each plane away from the laser focus, the power density distribution is relatively uniform. There are two defocus methods: positive defocus and negative defocus. If the focal plane is above the workpiece, it is positive defocus, otherwise it is negative defocus. According to geometric optics theory, when the distance between the positive and negative defocus planes and the welding plane is the same, the power density on the corresponding plane is approximately the same, but the actual shape of the obtained molten pool is different. When the defocus is negative, a greater penetration depth can be obtained, which is related to the formation process of the molten pool.

Laser welding machine operation steps

Before you start

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

2. Check whether the air connection of the equipment in the machine is normal;

3. Check that there is no dust, spots, oil stains on the surface of the machine.

4. Before starting the machine, turn on the power of the motion control components such as the automatic workbench, check whether the components are operating normally, and then turn on the computer under normal conditions.

Boot up

1. Turn on the power and turn on the main power switch;

2. Turn on the water cooler, laser generator, etc. in turn;

3. Open the argon valve to adjust the gas flow;

4. Enter the current working parameters to be executed;

5. Perform the welding operation.

Turn off

1. Exit the program and turn off the laser generator;

2. Turn off the dust collector, water cooler and other equipment in order;

3. Close the valve of the argon cylinder;

4. Turn off the main power switch.

That is to say, when operating the laser welding machine, 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 cause the equipment to operate abnormally. Only in this way can the laser welding machine maintain good processing results and bring us efficient and standardized production.