1.     Product Description

The laminar roller table is located behind the finishing mill of the hot strip mill and in front of the coiler. It is a transfer roller in the laminar cooling section. When the plates’ head enters the laminar roller table with the finish rolling of the hot-rolled plate completed. the conveying speed of the laminar flow roll is slightly higher than the plates to form the surface tension of the plates and ensure the flatness of the plates. In a similar way, the conveying speed of the laminar roller should be lower than the slab when the plates’ tail leaves the finishing stand. Because billet that is conveyed by the laminar roller table conveys is finished billet, the surface of the billet is not allowed with any defects such as roll marks and scratches. The laminar roller table should have a certain surface strength to prevent from the occurrence of sheet defect due to cracks and peeling of the laminar roller.

Under this working condition, the laminar roller table is required to not only bear the weight with loading (impact) of the hot billet, but also have a certain bonding strength to ensure the wear performance of the roller table. Under the action of cooling water spray, roll also withstands alternating loading (cold and heat fatigue), part press-in loading and contact sliding load. The working temperature of the conveying roller is between 400-600 degrees, and the contact medium is mainly water and water vapor.

2.     Traditional Crafts

For such hollow rollers with high bonding strength, anti-impact loading and anti-corrosive media, the previous laminar rollers adopt surface spray welding or surfacing technology, and the spray welding layer is only 0.5-0.7mm, and the surfacing layer of surfacing technology is 2mm, the hardness is about HRC45, the surfacing or spray welding technology has the characteristics of simple process and easy operation. From the actual effect of use, one hand, an uneven temperature field is formed partly due to the heat source on the laminar roller table, the inhomogeneous structure and residual stress produced by the weldment cause the metal of welding layer to crack, pores, slag inclusion, etc., Uneven hardness of the weld layer metal cannot effectively eliminate the welding residual stress, which causes the hardness and wear resistance of the weld layer metal to decrease. On the other hand, the laminar roller table runs in a high-speed, high-temperature, and water-cooled environment for a long time. The high-speed and high-temperature strip wears on the roll surface, the thermal stress and deformation of the hollow roll body, the roll surface cracking and shedding caused by thermal fatigue, and the peeling and peeling of the bonding layer due to water vapor erosion. These factors cause the weld layer to separate in a relatively short time, severe rust, other defects, and failure to be replaced and offline. With the increase in the output of broadband production lines, the requirements for plate shape and surface quality are getting higher and higher, and so higher requirements for the performance and lifetime of the laminar roller table are also one of the key issues for users to reduce production costs.

3.     Bimetal laminar roller table produced by centrifugal casting

We have more than ten years of centrifugal casting experience and have mastered mature centrifugal casting technology. The bimetal composite roller table produced by centrifugal method has different materials for roller body and core, the two materials are metallurgical combined. This kind of composite roller can not only meet the abrasion resistance of the roller body on boardband conveying, but also ensure the strength and toughness of the roller neck and the substrate. The materials of the outer layer and the base layer are mainly selected according to the specific requirements of the composite roller's performance during transportation. The surface hardness of the composite roller can reach HRC50-58 after special treatment, and it has the physical properties of no cracks, cracks, deformation, drumming and other defects under high temperature environment. The composite effect is good, the interface is dense, the bonding strength is high, and there is an obvious smooth transition layer between the substrate and the composite layer. We started the research and development since 2012, the bimetal composite roller table has been gradually adjusted and gradually adapted to the on-site working conditions. From the actual use effect, the composite laminar flow roller not only exhibits the advantages of substrate toughness and plasticity, but also has high wear resistance layer. It shows excellent performance during use. While ensuring the quality of the rolled plate, the online service life is guaranteed for more than 2 years, which is 1.5-2 times the service life of the laminar flow roll produced by the surfacing process. The extension of the service life reduces the consumption cost and the maintenance intensity of the staff, and improves the operation stability and operation productivity of the equipment.