Different from traditional cleaning processes such as shot blasting, sand blasting and sanding, the efficient and non-contact cleaning method of laser cleaning is consistent with the development direction of industrial green environmental protection in China. In the field of rails, ships, automobiles, military equipment, etc., there are broad development prospects in the fields of pre-weld cleaning, painting and cleaning.
Taking railway rails as an example, the railway network can be said to be a vital component of China's transportation network. At the end of 2015, China's total railway operation reached 121,000 kilometers, ranking second in the world. Among them, the high-speed rail mileage exceeds 19,000 kilometers, ranking first in the world. China's high-speed railways operate at speeds of 160-320 km/h, requiring the use of seamless lines (except for special road sections such as ballasts, tunnels, bridges, and platforms); seamless railways can save more than 15% of maintenance costs and extend rail usage by 25%. life. Nowadays, seamless rail has become the main type of track laying for the entire railway network in China, and the seamlessness of China's railway lines has reached more than 70%. The key process of seamless rail production is rail welding, and the cleaning technology of the rail is critical to the impact of welding.
Corrosion composition of railway rail surface: multi-component mixture of paper label, oxide scale, rust, paint, grease and dust. There are many problems with traditional grinding and cleaning:
1. Deep grinding to ensure cleanliness, but destroy the curved surface of the rail surface. There are uneven transition zones and gaps between the rails and between the rails and the hubs. The trains are seriously shaken, and the high-speed running trains produce micro-vibration, which reduces passenger comfort.
2. reduce the amount of grinding, to ensure the shape of the arc, but lead to serious rust residue. The welding current varies drastically over a wide range (unstable ± (200 ~ 1600 A)). The welding current is greatly changed, which causes the weld to produce defects such as coarse crystal grains and gray spots, which are difficult to detect, and which have buried serious safety hazards;
3. the current grinding and cleaning rust residue 20% ~ 30%, resulting in a welding failure rate of 10%; the repair process is extremely cumbersome, the cost of 30,000 yuan / welding head, restricting the seamless railway track production process;
4. the consumption of a large number of grinding wheel consumables, has caused dust pollution to the environment, causing serious harm to workers' health
5. railway maintenance and repair work is heavy, laser cleaning technology can replace manual grinding and cleaning to promote China's efficient automated railway online repair work process.
Laser cleaning can avoid the above problems and has the following advantages:
1. The cleaning light source can adapt the shape of the curved surface of the rail to minimize the damage of the substrate, the rust removal rate is greater than 99%, and the substrate damage is <0.01 mm;
2. No green cleaning technology for consumables, eliminating dust pollution and greatly reducing cleaning costs;
3. No green cleaning technology for consumables, eliminating dust pollution and greatly reducing cleaning costs;
4. The cleaning light source can be flexibly transmitted by optical fiber and integrated with the robot;
5. Greatly improve the cleaning quality, improve the welding yield, rail welding strength and reliability, and eliminate potential safety hazards.
The laser welding market is broad, and the corresponding pre-weld pretreatment requirements will also increase. The laser cleaning technology can achieve pre-weld pretreatment without damage to the substrate and no secondary pollution, which is a good helper for ensuring the welding quality.