Application of fiber laser cutting technology in rail transit industry

Laser cutting is the most important application technology in the laser processing industry. Due to its many characteristics, it has been widely used in automotive, rolling stock manufacturing, aviation, electronics and metallurgy. Lasers have different solutions in different industrial fields: laser cutting, welding, heat treatment, cladding and so on. Among them, laser cutting accounts for about 70% of industrial laser applications. Laser cutting is known for its high speed, high precision and high cutting quality. Combined with advanced CNC systems and machine tools, the laser has excellent performance in 2D and 3D cutting.

In the rolling stock manufacturing industry, complex vehicle welding structures are assembled from a large number of basic parts. To ensure the quality and dimensional requirements of the welding after assembly, the processing quality of a single basic part, such as flatness, straightness, slope The level of fineness of the mouth is very high. As the front process of the basic parts, the cutting quality of the board directly affects the welding quality of the product. At present, fiber laser cutting has relied on its high efficiency, fast and accurate advantages in the field of key parts processing of rolling stock, especially in the manufacture of stainless steel bodies and the manufacture of bogies.

First, the characteristics of laser cutting

Laser cutting is one of the best cutting methods in the cutting technology that people have mastered today. Compared with traditional cutting, laser cutting has the advantages of small working area, narrow slit, small thermal deformation, high cutting precision and low noise. It is non-polluting and easy to achieve automatic cutting. Although the initial investment is large, the processing cost is 50% less than machining, and the laser can cut non-metal. As an advanced manufacturing technology, laser cutting has the advantages of wide application range, flexible process, high processing precision, good quality, clean production process, and easy to realize automation, flexibility, intelligence and improve product quality and labor productivity.

Second, CNC fiber laser cutting equipment

Our company's laser equipment uses G3015F CNC fiber laser cutting and machining center produced by Han's laser. The equipment system is mainly composed of hardware system, software system and laser.

Equipment hardware system

(1) The machine adopts gantry structure, imported gear rack and high-precision linear guide rail. The transmission is stable and the precision is high. The configuration exchange table can make cutting and feeding at the same time, which greatly improves the production efficiency of the machine tool.

(2) The bed body adopts the whole welded structure, rough processing after annealing, and then vibration aging treatment, which can completely eliminate the stress of welding and processing, has good rigidity and high precision, and can be used for a long time without deformation.

(3) The beam is integrally casted with aluminum alloy, rough processed after annealing, and then vibrated and aging, formed by high precision machining, with good rigidity, light weight and good dynamic performance.

(4) The X, Y and Z axes adopt German Siemens high torque servo motor, which has high precision, high speed, high torque, large inertia, stable and durable performance, ensuring high speed and acceleration of the whole machine.

(5) The cutting head selects the special cutting head of fiber laser and the capacitive sensor produced by PRETECITE of Germany, which has high induction precision, sensitive response and the most stable and reliable performance.

(6) Import high-precision electronically controlled proportional valve to precisely control the air pressure of the cutting auxiliary gas to achieve the best cutting effect. It is much more precise and convenient than a manual pressure regulator.

2. Equipment software system

(1) It adopts PA8000 numerical control system based on Windows operating system, special numerical control system of laser cutting machine, integrates many special function modules of laser cutting control, powerful function, good man-machine interface and simple operation.

(2) Israel CNCCAD software is the core technology of CNC cutting machine to achieve "full-time cutting, high-efficiency cutting and high nesting rate cutting", which is the fundamental guarantee for effectively saving materials and improving cutting efficiency.

3. Fiber laser

The fiber laser cutting machine adopts the YLS-2500 high-power fiber laser of IPGPhotonics, a world-renowned fiber laser manufacturer, as shown in Figure 1.

The fiber laser can be coiled due to the optical path, and the optical path occupies less space. In the case of using a single-core junction semiconductor pump laser as the pump source, the pump laser can be dispersedly mounted and has good heat dissipation characteristics. In the case of low installation density, air cooling can be used; in the case of high installation density, only a small amount of water can be used to meet the heat dissipation requirement. Therefore, the volume of the all-fiber laser is the same as that of the same output gas. The laser system is smaller and lighter.

Compared to other lasers, fiber lasers have more accurate beam quality and a small divergence angle.

Third, the subway vehicle bogie anti-loose board cutting case

The bogie anti-loose plate is an irregular curve contour structure, the material is 1Cr18Ni9Ti stainless steel plate, the thickness is 8mm, and the curvature of the outer contour is variable. The tolerance of the middle pin hole is required to be 35+0.1+0mm, which requires a smooth transition of the machining area. A laser with a pulse power of 2.4 kW is used, the cutting speed is 2.2 m/min, and the focal length of the laser beam is 0.12 to 0.25 mm. It has been verified by practice that the products of fiber laser cutting can fully meet the practical requirements. Other subway base laser cutting parts are shown in Figure 2.

Fourth, the conclusion

In summary, the products using fiber laser cutting have narrow slits (0.1~0.5mm), small deformation, no burrs, wrinkles, high precision (hole center distance error 0.1~0.4mm, contour size error 0.1~0.5 Mm), the surface quality of the slit is good (Ra=12.5~25μm). Because the CNC laser cutting system is convenient for cutting workpieces of different shapes and sizes, it is often preferred over the die cutting and molding process; although the machining speed is slower than the die punching, it has no mold consumption, no need to repair the mold, and saves the mold replacement. Time, which saves processing costs and lowers product costs, is generally more economically economical.