威廉希尔官方下载Feb 17, 2020
There are mainly 5 factors which affecting the laser welding quality include:
Laser pulse energy; Laser beam spot diameter; Laser pulse frequency; Laser pulse waveform and relative light absorptivity of the material to be welded; Control characteristics: choice of feedback control method, power waveform.
1. Laser pulse energy
Laser pulse energy: refers to the energy that can be output by a single laser pulse, the unit is J (Joule). This is a main parameter of the laser. It determines the maximum energy that the laser can produce. According to the purpose of mold repair, the laser energy below 70J can already meet the needs of any occasion. No matter how large the energy is in vain, or at all It is unavailable, and the volume of the laser power source and the radiator are constantly increasing, which reduces the efficiency of the power supply.
2. Laser beam spot diameter
Laser spot focus diameter: This is an extremely important parameter reflecting the design performance of the laser. The unit is (mm), which determines the laser power density and processing range. If the optical design of the laser is reasonable and advanced, the laser energy is concentrated and the focus is accurate, the diameter of the laser spot can be controlled in the range of 0.2mm-2mm, and whether the focus diameter of the laser can be controlled at 0.2mm is a strict requirement for the laser generator. test. The lasers generally designed in China, because they only want to reduce the cost, therefore, the processing of the laser components is rude and the design is not rigorous. The laser diverges seriously in the resonant cavity, which makes it difficult to focus accurately. It is called 0.2mm, but it can only reach a minimum of 0.5mm. Due to the divergence of the laser, the output laser beam cannot be a regular circle, which causes the actual laser irradiation area to be too large and the phenomenon of ablation welds appears. That is, unnecessary laser irradiation at both ends of the weld seam causes the both ends of the weld seam to appear concave. This phenomenon is particularly serious for repairing polished molds, and sometimes even makes the mold scrap. Tongpu's lasers are well-designed, with strict selection of materials and careful debugging, so that the beam spot diameter of the laser output can be precisely monitored, so that the minimum spot size can reach 0.2mm, and can be in the range of 0.2mm and 2mm. Perform stepless adjustment to reach the international advanced level.
3. Laser pulse frequency
Laser pulse frequency: This is the ability to reflect how many pulses the laser can emit in one second. The unit is (Hz). The first thing to explain is that the welding metal is the energy of the laser. Under the condition of constant laser power, the higher the frequency, the smaller the energy output by each laser. Therefore, we need to ensure that the laser energy is sufficient to melt the metal In the case of considering the processing speed, the output frequency of the laser can be determined. In the case of laser repairing abrasives, 15Hz can already meet the needs of welding. Too high frequency will inevitably cause the laser pulse energy to be too low, resulting in welding failure.
4. Laser pulse waveform and relative light absorptivity of the material to be welded
Laser pulse waveform: For pulsed laser welding, laser pulse waveform is an important issue in pulse laser welding. When a high-intensity laser is incident on the surface of a material, the metal surface reflects 60% to 98% of the laser energy, and the reflectivity changes with the surface temperature. Therefore, different metals have different laser reflectances and laser utilization rates. For effective welding, lasers with different waveforms must be input, so that the metal structure at the weld can be crystallized in the best way to form the substrate. Consistent metal structure can form high-quality welds. Generally domestic machines use cheap single-waveform laser power supplies. Therefore, its welding flexibility is low, it is difficult to adapt to the welding of a variety of mold materials, and often rework, which greatly wastes the welding material time and may cause the mold's scrapped. The reflection and absorption of laser light on different metal material surfaces are very different, and the same laser beam will produce different welding effects on different metals, and affect its penetration, welding speed, crystallization speed and hardness. Therefore, a single rectangular wave Welding does not solve the requirements of different mold metal welding.
5. Control characteristics: choice of feedback control method, power waveform
When choosing the laser power waveform, in general, under the condition of inputting the same laser energy, the wider the pulse width, the larger the welding spot; the higher the peak power of the laser power waveform, the deeper the welding spot.