Reason analysis of automatic laser cutting machine

by:Lxshow     2021-05-25

⑴Because the fiber laser cutting machine is a newly purchased equipment, if you want to process high-quality products, you need to be familiar with the adjustment of related parameters, and you must have a deep understanding of machine tool performance and rich operating experience. The main reasons that affect cutting burrs are: 1) Improper laser focus setting; 2) Improper adjustment of laser power; 3) Improper adjustment of cutting speed; 4) Improper adjustment of gas pressure.

⑵As the length and width of the material are 1730mm×910mm, and the length has a 7mm error, it is difficult to guarantee the accuracy of the symmetry e after cutting, and it affects the production efficiency of laser processing.

⑶In the manual, the cutting gas used for cutting different materials is different. For carbon steel cutting, high-purity oxygen is used, and high-purity nitrogen is used for cutting non-ferrous metals and stainless steel. The material to be cut is SPT83BQ (Japanese steel grade), which is a high-strength carbon steel with a zinc alloy anti-rust layer on the surface. Pure oxygen is used as the cutting gas during trial cutting. As a result, the cutting section has serious nodules. .

⑷The laser cutting machine is a precision equipment, which has certain requirements for dust and vibration in the on-site environment.

Because the current laser cutting machine is installed in the stamping center plant, it is close to the blanking area and the riveting operation area. The dust in the blanking area and the smoke during the riveting operation are serious. The vibration of the machine is also large when the machine is working. The main reasons for the cutting production efficiency of the laser cutting machine are:

⑴The length error of the sheet;

⑵ Better cutting path select. Technical improvement countermeasures and implementation

Countermeasure 1: Determine better cutting parameters

⑴ Determine the laser focus position parameters. By debugging and comparing the cutting quality of the laser focus point at different positions with a material thickness of 0.65mm, it is determined that the quality of the cut section is better when the focus point is at the center of the plate thickness.

⑵Determine the matching parameters of laser power and cutting speed. Through repeated debugging, the cutting speed is increased from the original 3m/min to 5m/min, and the matching laser power is increased to 1200W, which can ensure that the quality after cutting meets the requirements.

3 Determine the gas pressure matching parameters.

At a cutting speed of 5m/min, the stability of the air pressure has a greater impact on the cutting burrs, and the greater range of air pressure fluctuations should be controlled within (1.0±0.2) MPa to ensure the cutting The quality meets the requirements.

Countermeasure 2: Determine the cutting material of SPT83BQ steel plate. According to the operating instructions, the carbon steel cutting gas uses pure oxygen, but SPT83BQ is a high-strength carbon steel with a zinc alloy anti-rust layer on the surface. The zinc alloy on the surface has a low melting point, causing serious oxidation nodules. After testing, it was decided to cut with 99.999% pure nitrogen according to the stainless steel cutting mode, and the burrs after cutting can meet the user's requirements.

Countermeasure 4: Design and manufacture fast positioning tooling to ensure the symmetry requirements after cutting, and to achieve fast and efficient positioning, reduce the time for adjustment due to sheet length errors, and improve production efficiency. Fast positioning tooling, as shown in Figure 5. After the implementation of the effect inspection countermeasures, the quality of the L11K laser cutting parts after the continuous production of 2000 pieces was counted. Judging from the above statistics, the pass rate of cutting burrs is 99.6%, which is a greater improvement than the trial production. However, in actual operation, it is found that the cutting gas used in production is 5.3m3/bottle of pure nitrogen. When each bottle of nitrogen is almost used up, the operator must adjust the cutting air pressure in time due to the drop in air pressure, otherwise the cutting burrs will become larger. In addition, due to the high consumption of nitrogen when cutting with nitrogen, a bottle of nitrogen needs to be replaced every time about 15 pieces are cut. The replacement time of each bottle of nitrogen takes about 7 minutes, and it takes 49 minutes to change air every day. The production efficiency is low, and the site There are many accumulations of gas cylinders, which seriously occupy the production site. Develop improvement measures

⑴In order to reduce the time taken for changing bottles and improve production efficiency, it was decided to use 120kg/tank of liquid nitrogen. Each tank of liquid nitrogen is equivalent to 20 bottles of 5.3m3/bottle of pure nitrogen.

⑵In order to solve the problem of serious icing on the surface of the tank body during the gasification of liquid nitrogen, the gasification volume cannot keep up with the gas consumption during cutting, consider adding a set of vaporizers and combining the two tanks Liquid nitrogen is used in parallel to meet production needs.

(3) Modify the subroutine in the cutting program and close the nitrogen control valve during the idle stroke to save gas consumption.

⑷Strengthen the monitoring of gas cylinder pressure, and stipulate that the cylinder pressure should be checked every 100 pieces cut. Implementation effect after improvement After the implementation of the improvement measures, the cutting quality of L11K laser cutting parts is relatively stable, the monthly output is stable at 4000-5000 pieces, and the final inspection pass rate reaches 99.9%. Since a large tank of liquid nitrogen is used instead of the small bottle of nitrogen, each large tank of liquid nitrogen can cut about 300 pieces, while the small bottle of pure nitrogen can only cut 15 pieces, and each piece can save about 2 yuan of nitrogen. And because of the modification of the numerical control subprogram, the nitrogen consumption when the idle stroke is closed can save 0.12 yuan per piece. The frequency of gas replacement has also been reduced from 7 times a day to once every 2 days, which can save more than 100,000 yuan in manufacturing costs a year.

Through the development and research of the L11K project, a lot of laser cutting production experience has been accumulated. In laser processing, in addition to the above factors, the cutting quality is also related to the nozzle diameter, the distance between the nozzle and the processed part, the coaxiality of the nozzle and the beam, the surface cleanliness of the lens, the spot adjustment of the laser Y-axis flight constant light path, Many factors such as the purity of the shielding gas in the laser light path are related. Although the problems in the laser processing of L11K thin plate parts have been solved this time, further experience is still needed in the processing of different materials and plate thickness materials.

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