Our country is one of the few major agricultural countries in the world. With the accelerating pace of reform and opening up, China began to promote agricultural mechanization and automation on a large scale. According to statistics, in 2000, China's agricultural mechanization degree has reached 48%. However, due to the low level of the agricultural mechanization manufacturing process in China, there is still a big gap between product reliability, safety, durability and adaptability and developed countries. In particular, the key parts of agricultural machinery directly affect its service life, such as rotary farming knives, harvester cutters, ditches and other key wear-resistant parts of the failure greatly increased the maintenance cost, but also seriously affect the efficiency of agricultural machinery. At present, most of the maintenance of agricultural machinery is only a simple disassembly and replacement, which not only increases the operating costs of agricultural machinery enterprises, but also hinders the popularization of agricultural mechanization in our country.
For the relatively slow development of traditional agriculture, the advanced laser technology is applied to the agricultural field, the most striking of which is the laser cladding technology for the repair and strengthening of agricultural machinery.
Laser cladding is a surface modification technique for the substrate. By setting the cladding path in advance, the cladding material and the substrate surface are rapidly melted into a melting pool by laser irradiation, and then quickly solidified into a cladding layer with metallurgical bonding and low dilution, so as to repair the mechanical parts in situ, or improve the wear resistance, corrosion resistance, heat resistance, oxidation resistance and other properties of the original substrate surface.
Laser cladding technology has the following characteristics compared with traditional processing technology
1. Metallurgical bonding can be formed between the cladding layer and the substrate.
2. The matrix has little thermal influence and is not easy to deform.
3. The dilution rate of the cladding layer is low, saving expensive cladding materials.
4. The thickness of the cladding layer can be controlled.
5. It can repair specific parts of parts and other parts that are difficult to deal with.
Before the parts of agricultural machinery are repaired, the surface of the parts of agricultural machinery needs to be pretreated. Due to the harsh working environment of agricultural machinery, the surface of agricultural machinery parts often carries soil, oil, water, fertilizer, pesticides, rust, oxide layer, etc., so it is more complicated than parts repair in other fields. For the parts of agricultural machinery, the general operation is to wash the surface dirt of the soil contact farming parts with water first, if the dirt on the damaged surface is firm, you can use the method of mechanical sandblasting to clean up. The engine, shaft and other parts are cleaned with detergent first. After that, the surface to be coated is sanded and cleaned with acetone to avoid defects caused by surface stains entering the cladding layer during laser cladding, which will affect the quality and performance of the cladding layer.
Ultra-high Speed Laser Cladding, also known as Extreme High-Speed Laser Cladding (EHLA), invented by Fraunhofer ILT of Germany, is praised as the most competitive process available to replace electroplating technology due to the innovative technological progress it brings to the industry. The ultra-high speed laser cladding technology essentially changes the melting position of the powder, so that the powder will melt at the intersection of the laser above the workpiece, and then evenly coated on the surface of the workpiece.
The main technologies of traditional agricultural machinery repair are heat treatment, chromizing treatment, arc spray, etc., but they are difficult to meet the requirements of wear resistance, corrosion resistance, and pollution-free agricultural machinery. With the continuous development of laser cladding technology, the properties of the cladding coatings prepared are becoming more and more excellent. Therefore, scholars began to study the application of laser cladding technology in the repair and strengthening of agricultural machinery. In addition to repairing damaged parts, laser cladding technology can also be used to strengthen the performance of existing agricultural machinery parts.
As early as 2009, Chinese researchers have explored the laser treatment of the surface of rotary farming knives. Through orthogonal experiments and range analysis, it is found that the main effects of laser power > scanning speed > spot diameter. After laser surface cladding, the matrix structure is obviously refined, and many small high-carbon martensite is formed in the cladding area, which increases the microhardness and improves the anti-wear performance of the rotary tilting knife. Then, through the design optimization experiment to compare the general heat treatment, laser heat treatment and laser cladding single surface modification technology to prolong the service life of the lawn mower blade, the laser cladding is better than the first two.
Therefore, it is of great practical significance to explore the advanced repair technology and performance improvement means of the key parts of agricultural machinery for improving the service performance of agricultural machinery and prolonging its service life.
Xi'an Guosheng Laser took the lead in introducing ultra-high speed laser cladding technology to the Chinese market, and has built itself into an international R&D platform integrating laser processing, intelligent equipment integration and process research and development. To provide customers with materials, technology, testing, equipment, processing to large-scale production line production of the whole production chain professional services.