When using the protective lens of a laser cutting machine, the following methods can be used to avoid the rupture of the lens:
Gas Circuit Management
Pure Gas Source: Only use clean and dry cutting gas, such as nitrogen and oxygen commonly used in laser cutting, and ensure that the gas purity meets the requirements. The vaporizer should be designed according to the maximum gas consumption of the machine tool, and stainless steel pipes should be used to connect the gas source to the machine tool, reducing the use of hoses to minimize pressure differences. Install a pressure reducing valve and a filter at the air inlet of the machine tool. Cylinders or cylinder groups should not be used for high-pressure nitrogen cutting. For example, the gas produced by the air compressor should go through strict filtration to remove impurities such as oil, water, and dust to prevent the contamination of the lens.
Gas Circuit Inspection:
Gas Circuit Connection: Try to use ferrule-type pipe joints for the connection ports of the air pipes, use quick-connect interfaces and 90° interfaces as little as possible, and avoid using PTFE tape or thread sealant to prevent debris from entering the gas circuit, causing blockages that lead to unstable cutting and lens cracking.
Segmented Detection: Inspect the two parts of the gas circuit separately, from the gas cylinder to the outlet of the air pipe and from the outlet of the air pipe to the connection port of the cutting gas of the cutting head. Wrap a clean white cloth around the outlet of the air pipe and let the gas pass through, or place a clean protective lens/glass at the outlet and let the gas pass through at a low pressure to check whether there is water, oil, and the phenomenon of air hammer; you can also conduct a gas circuit test, run the perforation and cutting process without emitting light, and check whether the protective lens is clean.
Operation Specification
Pre-blowing Setting: Blow out gas about 2 seconds in advance before perforation, and then emit light for perforation after the cutting gas pressure reaches the set value. Keep blowing gas during the perforation and the process of descending to the cutting follow-up position. Switch the air pressure during the empty travel movement and keep the gas on. After the cutting is completed, stop the gas after a delay of 2-3 seconds when the cutting head is lifted in place.
Reasonable Parameter Setting:
Perforation Parameters: Reasonably set parameters such as the number of perforations and the frequency according to the material and thickness of the plate to avoid damage to the lens caused by the sputtering during perforation due to too high output frequency. For example, when the frequency is 500hz, the number of continuous wave perforations generally should not exceed 150. For instance, the perforation parameters need to be set differently when cutting thin plates and thick plates.
Other Parameters: Adjust parameters such as the focal length, cutting speed, power, and air pressure to make them match each other. For example, when the power is increased, if the parameters are not set properly, the lens is likely to rupture due to excessive instantaneous energy.
Correct Operation Sequence: First blow the protective gas, then emit light for perforation, and carry out cutting after the perforation is completed. When using the nesting software for layout, check the option of "perforating all common-edge graphics" to prevent the explosion of holes from burning the lens (especially for common-edge cutting of medium and thick plates).
Equipment Maintenance
Regular Cleaning: Regularly use clean pure cotton wiping paper (such as Webril wiping paper), cotton balls, lens paper, or cotton swabs, etc., dipped in optical-grade solvent (such as anhydrous alcohol) to gently wipe the lens. Before and after cleaning, use magnifying equipment and strong light to check the surface of the lens, and promptly find and remove pollutants, defects, burn marks, etc
Component Inspection: Regularly check the operation status of the air compressor and the dryer to ensure their normal operation; check whether other lenses of the cutting head (such as the middle protective lens, focusing lens, collimating lens) and the end face of the optical fiber are damaged, and deal with the problems in time to prevent affecting the protective lens; check the sealing ring of the protective lens, and replace it in time if there is aging or looseness.
Lens Selection and Installation
Select High-quality Lenses: Choose lenses produced by professional manufacturers to ensure good coating quality, excellent material, standard thickness, and no error in the edge size, avoiding rupture caused by the quality problems of the lens itself. For example, inferior lenses have a fast temperature rise, are easy to delaminate, and are easily damaged during cutting.
Standard Installation Operation: Avoid using excessive force during installation to prevent collision with hard objects; do not touch the mirror surface with your hands. Wear gloves and use special tools (such as optical tweezers, vacuum tweezers) for operation, and only hold the frosted edge of the mirror edge and other non-optical surfaces; pay attention to the correct installation direction of the lens to prevent it from being installed in the wrong direction.
--Jack Sun--