Iron and steel metallurgy industry is the basic industry of the country. At the same time, it belongs to the country's heavy industry, with complex equipment, many types and heavy tonnage. Due to friction, wear and other reasons, a large number of spare parts will be consumed every year to maintain the normal operation of the equipment. Therefore, reducing the consumption of spare parts and remanufacturing and repairing the used equipment plays a positive role in reducing the production cost and improving the economic benefits of the enterprise, and there is a lot of room to reduce the cost. Among them, laser remanufacturing technology is of great practical significance for the repair and repair of spare parts and the energy saving and consumption reduction of enterprises.
Main types of laser remanufacturing technology
1. Laser quenching
Laser quenching technology is to use the focused laser beam to shoot into the surface of steel materials to rapidly raise the temperature above the transformation point. When the laser is removed, due to the rapid heat conduction of the inner material still at low temperature, the heated surface is quickly cooled below the martensitic transformation point, so as to realize the surface transformation hardening of the workpiece. For example, the maximum hardened layer depth of laser melting quenching on the surface of large roll can reach more than 2mm.
2. Laser cladding and alloying
Laser cladding technology is a process that uses laser beam to cladding a layer of materials with special properties on the surface of selected workpieces to improve the surface properties of workpieces. For a large number of vulnerable parts such as roll, guide, conveying roll, pinch roll and shear blade in the metallurgical industry, the biggest advantage of laser cladding and alloying technology is to turn the overall alloying of roll into surface alloying or cladding, which greatly improves the service life of vulnerable parts such as roll and the increase of production cost is limited. Obviously, whether the design, selection and use of alloy powder are correct or not is the key to the success of this technology.
3. Laser welding
Laser welding is one of the important aspects of the application of laser material processing technology. Its principle is to radiate high-intensity laser to the metal surface, and melt the metal to form welding through the interaction between laser and metal. Because of its unique advantages, it has been successfully applied to the precision welding of micro and small parts. For example, the typical cold rolling process route dominated by China's iron and steel industry is: converter smelting - external refining - blooming - hot continuous rolling - Pickling - cold rolling - annealing - leveling - galvanizing (TIN) - finished products. In this typical cold rolling process, strip welding equipment is essential. In the process of operation, the first steel strip and the second steel strip must be welded to ensure the continuous operation of the production line. When silicon steel plate and strip is running online, it needs to undergo multiple "s" bending deformation and bear a certain running tension, so it has high requirements for the performance and quality of welds.
Application of laser remanufacturing technology in iron and steel metallurgy industry
1. Repair and strengthening of roll
Most of the production equipment in the metallurgical industry work under the harsh environment of high (alternating) stress and high thermal stress, such as continuous casting roll, straightening roll, groove roll, semi steel roll, pipe mold, hot (cold) rolling work roll, blast furnace chute, bell, etc. Among these equipment, all kinds of rolls are undoubtedly the most critical equipment parts, with large consumption, high price and long service life. They are not only closely related to the product cost, but also directly determine the quality of iron and steel products, especially the surface quality and plate shape. Laser surfacing is used to repair all kinds of rolls, among which small rolls and local repair are better. If the performance can be new.
Laser quenching technology can strengthen the surface of various guide rails, large gears, journal, cylinder inner wall, molds, shock absorbers, friction wheels, rollers and roller parts.
Laser textured automobile plate is called "mirror steel plate" abroad because of its high gloss of reflection image after painting. It is a high-quality plate for the production of high-end car panels. Therefore, laser textured cold-rolled sheet (strip) is an important raw material for the production needs of automobile, household appliances, electronics and light industries.
2. Repair of wear, Bush holding and crack of various shaft parts
After laser surfacing treatment, the surfacing layer of various shaft parts has no coarse casting structure, the surfacing layer and interface structure are fine, the grain is fine, and there are no defects such as holes, sand holes, inclusions and cracks. The performance is like that of new parts.
3. Repair and strengthening of various high value-added large, medium and small gear parts in metallurgical industry
Laser surfacing technology can restore the performance of various high value-added large, medium and small gear parts. The acceptance index is still carried out according to the original manufacturing standard.
4. Repair of high pressure and high speed fan blades
The blade is easy to be seriously corroded and worn at the air inlet of the impeller blade due to its poor working environment. Generally, it is scrapped due to the imbalance between the corrosion and wear of the impeller blade after 3000 ~ 4000H. Using laser surfacing technology, the repair layer can be metallurgically combined with the original substrate, and the hardness can reach about HRC55. Service performance is like a new part.
Cost analysis of laser remanufacturing technology
The biggest cost of laser processing is that the one-time investment of equipment is relatively expensive. Once the equipment is invested, the operation cost is relatively low without considering the investment cost of equipment. As rolls, shaft parts, blades and gears in iron and steel metallurgical equipment are high value-added parts, the cost of laser processing is less than 25% of the original value. Moreover, the cycle of laser processing is short, which can greatly save the maintenance time, so as to ensure timely production, and the performance is like new parts.
Source: JiuHeng photoelectric laser cladding
