High Power Laser Cutting Equipment and Technology

In recent years, the rapid development of high-speed rail, nuclear power, shipbuilding, petrochemical, aerospace and other fields, put forward higher demand for laser cutting processing equipment and technology, the general trend is towards higher power, faster, more and more thick format cutting section, brighter and more straight direction the development of. At present, the development of laser industry is more and more active. Fiber laser power technology and optical components technology constantly break through. It will promote the installed power of laser cutting machine.

The laser power equipment to break the million kilowatt class, first of all need to achieve reliable and stable light source technology. In the field of laser cutting, fiber laser power coupling 12kW into 100 m, its core technology is the coupling technology, packaging technology, thermal stress, thermal management, management control and spot control spectrum, light source module currently has 500W, 700W, 1000W and 1500W, 2000 W / module will be launched recently, implementation the long-term stability of the output power by increasing the single module redundancy; TRUMPF disk lasers through power control, each module has only a 1000W. No matter what light source, the BPP value of the beam quality in the cutting process is generally not greater than 8mm mrad, and the electro-optic conversion efficiency is not less than 30%.

To solve the technical problems of the beam transmission of high power laser equipment is also very important. Due to optical processing capacity constraints, it is difficult to fabricate optical components shaping effect is good, high diffraction limit, to a certain extent, restricts the development of high power laser transmission technology, how to improve the optical surface polishing technology, optical device for high diffraction efficiency of producing ability is the future development and application of ultra high powered laser challenge. High power laser power from the fiber core 100 m diameter inner injection, its power density in general, as can be imagined, composed by the laser transmission path through the fiber end mirror, QBH or QD interface, collimation lens, zoom lens, a focusing mirror and a mirror under protection, given the ultra high power density all of the above, the optical lens on the path of cleanliness and the temperature rise of the stringent requirements, the optical path must be strictly sealed, there shall be no medium exchange with the outside world, and shall be installed in the clean room and clean optical devices, in addition the link cooling loop pressure and flow, the water inlet and the water temperature sequence and are equally important. To ensure that the temperature of cutting process remained relatively constant. Generally speaking, there must be a laser cutting knife hole, especially cutting plate materials, perforation quality is very important, good perforation is the foundation to ensure the stability of light and air, high power laser cutting, zoom perforation technology is relatively distance control beam expanding lens and a focusing lens group with servo motor, realize the change the focal spot of positive and negative defocus, cutting of stainless steel, aluminum, brass and copper and Aluminum Alloy need negative defocus, the greater thickness of negative defocus deeper.

Due to the error of material and size and other factors make optical lenses (including light window mirror, collimation mirror and a focusing mirror) has the small differences in the processing process, these errors will cause some subtle differences in different lens focus position of the same size, while the laser cutting machine of optical system during installation various types of optical link and adjust gas and cleanliness will also cause the focus drift, fast search and determine the focus position and the use of intelligent cutting control system can be automated, than the previous manual adjustment in two aspects of efficiency and accuracy are greatly improved. The accurate focus position is one of the key factors to realize high quality and high efficiency cutting.

The intelligent cutting control system has the function of high speed perforation, which can save energy and improve the efficiency of perforation. Perforation is the work that must be prepared before laser cutting. For the traditional timing piercing process, the efficiency and safety of some contradictions, to ensure fast and reliably complete perforation, usually in the time of perforation on the left there is a margin, but in order to prevent the molten pool in the process of perforation hole explosion and pollution will limit the power of the lens, thus affecting the efficiency of perforation, perforation. Intelligent cutting control system, due to the online monitoring and control of perforation, predict and control of various process parameters in molten pool blast hole before, the laser at full power under the condition of high speed, high quality and complete perforation, and can automatically determine the end of perforation, perforation immediately after the end of follow-up cutting, can greatly shorten the processing time, processing quality assurance, but also can greatly reduce the excess energy and due to perforation of the bed of ablation and thermal deformation effect.

Many factors affect the quality of laser cutting, in many factors, nozzle structure, auxiliary gas type, pressure and flow rate for cutting quality has important effect, especially in high power laser cutting technology put forward higher requirements on the nozzle structure and related parameters. At present, the cutting nozzle with single hole type and composite type two, light hole and jet hole in cylindrical and tapered, simple processing, low production cost, but the aerodynamic performance is poor, poor gas energy, the gas loss is too large, basically meet the cutting power is less than 6kW. When the application of high power laser cutting 50mm thick stainless steel, the test results prove that the La Farge nozzle is high pressure plate structure of fast cutting optimum technology, the ultra high speed, high steady flow, and internal entrance slits cut in the cut, cut to form a stable and high quality.