The laser cutting machine is to focus the laser emitted from the laser into a high power density laser beam through the optical path system. The laser beam shines on the surface of the workpiece to make the workpiece reach the melting point or boiling point, while the high-pressure gas coaxial with the beam will blow away the molten or vaporized metal. With the movement of the relative position of the beam and the workpiece, the material will eventually form a slit, so as to achieve the purpose of cutting.
Laser cutting processing uses invisible beams to replace the traditional mechanical knife. It has the characteristics of high precision, fast cutting speed, not limited by cutting patterns, automatic typesetting to save materials, smooth incision, low processing cost, etc., and gradually improves or replaces the traditional metal cutting process equipment.
1、 Working principle of laser cutting machine
The laser cutting machine needs a pressurized gas source as power when working. The commonly used auxiliary gases are oxygen, nitrogen and compressed air, and sometimes argon. According to the gas pressure, it can be divided into high-pressure gas and low-pressure gas.
With the demand for the thickness and efficiency of cutting plates, the pressure of compressed air has also developed from 1.25 MPa~1.3 MPa to a higher pressure, even reaching 2.0 MPa~3.0 MPa. At present, 1.6 MPa compressed air is mainly used in the market.
2、 Influence of oil in compressed air
At present, the gas sources are mainly nitrogen, oxygen and compressed air. Nitrogen or oxygen will be used unless some precious metals are processed or the processing requirements are high, and more compressed air will be used.
Compressed air can be directly supplied by air compressor, which is easy to obtain and very cheap compared with oxygen and nitrogen. Although the air only contains about 20% oxygen, the cutting efficiency is far less than that of oxygen cutting, but the cutting capacity is close to that of nitrogen, and the efficiency of air cutting is slightly higher than that of nitrogen cutting. It is an economical and practical choice to replace nitrogen cutting with compressed air.
The quality of compressed air has a very direct impact on the quality of laser cutting. The compressed air contains water mist and oil. If it is not cleaned and high-pressure jet is sprayed onto the lens surface of the laser cutting head, the transmission of the laser beam will be seriously affected, the focus will be scattered, and the product will not be cut through, resulting in waste products.
If it is a high-power laser cutting machine, as long as the mirror or nozzle surface is protected by a little tiny oil film or water mist, it may also cause high-energy laser emission to burn the laser head. Since the price of the laser head of the super power laser cutting machine is more than 10000 yuan, and most compressed air can't handle the oil and water in the compressed air very well, even if the new machine can meet the requirements, the effect of oil and gas separation will become worse with the use of the equipment, and the oil content in the compressed air will also become larger, bringing uncertainty to the use. Therefore, most users of ultra high power laser cutting machines are unwilling to take the risk of using compressed air as auxiliary gas.
3、 Acquisition of oil-free compressed air
In compressed air, water removal is relatively easy. Only the matched refrigerated dryer and filter are required to meet the requirements. However, it is more difficult for the compressed air to contain no oil. If the oil-free engine is selected, it will undoubtedly increase the purchase cost of users. In addition, it is difficult to do so under such high pressure.
The "oil-free" compressed air is produced by using a non oil-free compressor, that is, the compressed air is obtained by using a conventional lubricating oil compressor, and then processed by the back-end oil removal equipment to obtain oil-free compressed air.
This configuration has treated the moisture and dust particles in the compressed air, and more importantly, purified the gaseous oil in the compressed air, so as to avoid the lens of the laser cutting equipment from being polluted.
Compressed air purifier is mainly composed of high-efficiency heat exchanger, reactor, electric heater, electric control system, etc.
The compressed air from the compressor enters the filter after passing through the air storage tank through the pipeline. When passing through the filter, the compressed air will effectively separate the liquid water contained and protect the reaction system; The compressed air after separating the liquid water enters the high efficiency heat exchanger, in which the low temperature gas from the precision filter and the high temperature gas from the reactor conduct full heat exchange; The heated high temperature compressed air enters the reactor, and the oil impurities in it will undergo catalytic oxidation reaction on the catalyst surface at the temperature of 180~220 ℃ in the reactor:
CnHm+(n+m/4)O2→nCO2+m/2H2O
All of them are converted into carbon dioxide and water. At the same time, under the action of high temperature, the biological bacteria in the compressed air are killed to achieve the oil removal and sterilization of the air source and obtain high clean compressed air; The purified high temperature gas is sent to the user's gas unit after the heat is recovered by the high efficiency heat exchanger; The whole process is automatically adjusted by a high-precision temperature control system, which is safe and stable.
4、 Use effect
This combination of micro oil screw and purification device has been well applied in some electronic, food, photovoltaic and other working conditions that require no oil. After follow-up tracking in the use of the supporting laser cutting machine, the use effect has also met the customer's expectations.
Any new products and technologies are constantly developed and improved in practice, and related technologies should also keep pace with the times and adapt to new requirements.
Source: Hannimik
