What factors will affect the quality of laser welding?

Date：2023-01-06 14:52:42 Views：1330

The application of laser welding technology in the world is more and more extensive, and many industrial manufacturing fields in China need to cooperate with laser welding machines to complete the processing of some objects. How to correctly set and control these parameters in the high-speed continuous laser welding process, and control them within the appropriate range, so as to ensure the welding quality. Laser cutting manufacturers believe that the reliability and stability of weld formation is an important issue related to the practicality and industrialization of laser welding technology. The main factors affecting the quality of laser welding are welding equipment, workpiece conditions and process parameters.

1、 Welding process parameters

The welding process parameters that affect the quality of laser welding mainly include: laser power welding speed, lens focus, focus position, shielding gas, etc. Laser power and welding speed are the most important parameters affecting the welding quality. The welding thickness depends on the laser power, which is about 0.7 power of the power (KW). Generally, the power increases and the welding depth increases; With the increase of speed, the penetration becomes shallow, the weld seam and heat affected zone become narrow, and the productivity increases.

2、 Welding fixture

In the process of laser welding, the welding fixture is mainly used to accurately position and reliably clamp the welding workpiece, facilitate the assembly and welding of the welding workpiece, ensure the accuracy of the welding structure, and effectively prevent and reduce the welding thermal deformation.

3、 Welding equipment

Goldsmith laser welding machine is usually composed of laser, light guide and focusing system. These systems have a certain impact on the quality of laser welding. The lasers used for welding mainly include pulse lasers and continuous lasers. The most important performance is the output power and beam quality. The most important quality requirements for welding are the stability of the beam mode and output power. The lower the beam mode order is, the better the focusing performance of the beam is, and the smaller the light spot is. The higher the laser power density under the same laser power is, the greater the welding depth width ratio is. The better the stability of the laser output power is, The welding consistency is better.

The light guide and focusing system is mainly composed of optical fiber, collimating (beam expanding) mirror, reflector and focusing mirror to realize the function of transmitting light beam and focusing. Under the action of high-power laser, the performance of these optical parts may deteriorate to reduce the transmissivity, resulting in thermal lens effect (the thermal expansion focal length of the lens changes). If there is surface contamination, it will increase transmission loss and even cause damage to optical parts. Therefore, the quality, maintenance and working condition monitoring of optical parts are critical to ensure welding quality.

4、 Workpiece status

The machining accuracy, assembly accuracy and cleanliness of metal tight laser welding workpieces are generally not filled with metal because of the small laser spot and narrow weld seam. If the assembly is not tight and the gap is too large, the beam will pass through the gap and cannot melt the base metal, or cause obvious undercut and depression. Therefore, the butt assembly gap and the butt seam deviation of the light spot of a strand of plate shall not be greater than 0.1mm, and the misalignment shall not be greater than 0.2mm. Of course, for workpieces with higher welding quality requirements, The machining accuracy and assembly accuracy of the welding workpiece are also higher, especially for the manual assembly before welding, to ensure the height difference of the welding position, assembly clearance and the cleanliness of the workpiece.

The homogeneity of materials means that one or several properties of materials have the same composition or structure. The homogeneity of materials directly affects the effective use of materials. The factors that affect the uniformity of materials include the distribution of alloy components, material thickness, etc. The type and content of alloy elements themselves have an impact on the welding quality, and the uniformity of their distribution directly affects the consistency of welds. For example, when aluminum alloy materials are welded, the distribution of alloy elements is uneven, or the content of impurities inside is different, so welding defects are easy to occur: holes, undercuts and dents.

To sum up, in the high-speed and continuous laser welding process, and within the scope of integration, to ensure the welding quality, such as the reliability and stability of weld formation, to ensure the welding quality, on the one hand, it is necessary to use lasers with good beam quality and stable laser output power and optical elements with high quality and stability to form its light guide focusing system, and maintain it regularly, prevent pollution, keep it clean, and properly pretreat the workpiece; On the other hand, it is necessary to ensure the processing accuracy and assembly accuracy of the workpiece, set different laser processing parameters for different processing materials, select appropriate laser power, welding speed, laser waveform, defocusing star and shielding gas, optimize processing parameters according to different welding effects, and improve the reliability and stability of laser welding stars.

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