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The adverse effects of inferior laser cutting head protective mirror

The laser cutting head is used in a harsh environment. In order to protect the internal optical path and core components, especially the expensive parts such as collimation and focusing lens, the cutting head must be equipped with upper and lower protective lenses. Dust and splashes generated on the surface of the workpiece during the cutting process should enter The cutting head will cause serious damage to the focusing lens, and the lower protective lens can block these dust and splashes.

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The cleanliness of the protective lens directly affects the processing performance and quality of the laser cutting machine. If the lens is dirty, it will not only affect the cutting effect and efficiency, but will also further cause the internal parts of the cutting head and the laser output head to burn out, so limited materials need to be used. A protective lens with high light transmittance and low thermal expansion coefficient. When the lens is dirty during processing, it needs to be cleaned or replaced.

Protect lens processing has special technological requirements, from the selection of base material, processing accuracy, surface defects, coating, stability, mechanical properties (specific gravity, brittleness, tensile strength, compressive strength, hardness), processing flow (material preparation, waste Folding, sand hanging, grinding, core taking, coating) all have different processing requirements, and the finished products can only be shipped after strict quality inspection.

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In order to reduce costs, low-quality protective lenses use common base materials. The coating process is not guaranteed. The light transmittance is poor, heat-resistant, easy to break, and cannot withstand the penetrating power of the laser, causing the lens to blow holes, and the powder particles of the broken lens will contaminate the whole The cutting head will damage the core high-value components including the focusing lens and sensors. The maintenance cost will be as high as 20-50% of the price of the new cutting head, and it will delay the terminal production and processing, causing greater economic losses.

Poor quality protective lens is easy to cause adverse effects:

1. The thermal lens effect causes the focus of the cutting head to drift

The poor quality of the protective lens will increase the absorption rate of the laser. After a long time of continuous exposure, the temperature will increase and cause thermal deformation, which will cause the thermal lens effect to cause the focus of the cutting head to drift. The higher the power, the processing of high-reflective materials, and the thermal expansion of optical components The faster, the more obvious the thermal lens.

When cutting stainless steel, the thermal lens effect focus shift will cause inconsistent cutting section effects, more and more dross, and even continuous cutting problems; when cutting carbon steel, the thermal lens effect will cause more and more bottom slag and continuous cutting problems .

2. Protect lens burn point/burn through

The protection lens of poor quality is poor in blocking dust and spatter during the processing process, and it is easy to burn spots; for the ultra-high power processing head of 10,000 watts, the protection lens needs to be carefully selected. The protection lens of poor quality is in the 10,000 watt laser Under the action, serious conditions will directly cause the lens to burn through.

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3. Focus on the lens burn point

After the protective lens burns through, if it is not found in time, the light processing will continue, and the cutting will produce particulate smoke and dust, which will pollute the mounting components, the sealing ring and the lower surface of the focusing lens, which will also cause burns on the surface of the focusing lens. Deep cleaning and replacement of the entire set of mounting components and Focusing lens module.

4. The laser output head is burned out

For 10,000 watt laser equipment, once the protective mirror burns through, under the action of the 10,000 watt ultra-high power, it is very easy to instantly burn the internal collimator and focus lens module of the cutting head. In the most serious case, when the internal optical components of the cutting head are damaged, the optical path will be abnormal. Turning the head will cause abnormal heating of the window of the laser fiber output head, which will eventually burn out the QBH or LOE crystal, and the entire laser output head needs to be replaced.