Application of polymer materials in the wear problem of F3 rolling mill in CSP rolling line

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summary: The F3 rolling mill of the CSP thin slab continuous casting and rolling production line of a steel plant has a wear problem on the mating surface of the rolling mill archway and the bending roll cylinder. This article analyzes the cause of this problem and proposes a corresponding solution. It uses Fushilan polymer composite materials for on-site repair. After the repair is completed, it is continuously tracked and the use effect is good. It proves that the archway repaired by Fushilan products has good pressure resistance and corrosion resistance. keywords: Rolling mill arch wear ； Rolling mill stand ； Lining board ； skateboard ； CSP ； Roll bending cylinder ； 1. Equipment Introduction In the CSP thin slab continuous casting and rolling production process, the plate shape control technology has the greatest impact on the strip yield. The CSP rolling area is an important area for controlling strip forming. The CSP rolling area is mainly composed of F1-F7 seven-stand rolling mills, high-pressure water phosphorus removal devices, AGC, CVC, and loopers. The quality of its equipment directly affects the product yield. Once the opening size of the rolling mill arch is out of tolerance, it will inevitably make it difficult to control the operating status of the rolling mill and weaken the stiffness of the rolling mill frame, resulting in a decrease in product rolling quality and affecting rolling accuracy and equipment service life. 2. Analysis of equipment problems and causes. The F3 rolling mill in the CSP thin slab continuous casting and rolling workshop of a steel company has a wear problem of the rolling mill arch. The F3 rolling mill arch of the rolling line and the mating surface of the work roll exit bending cylinder, the work roll exit bending cylinder and the liner mating surface have wear and corrosion on a total of four mating surfaces. The wear amount is about 3mm. Due to the harsh working conditions of the rolling mill, cooling water is needed to cool the rolls during rolling. The matching gap between the rolling mill arch and the lining plate will cause the cooling water of the rolls to be mixed with the iron oxide scale on the surface of the rolled piece and enter the mating surface, thereby aggravating wear and tear. Corrosion is an important cause of damage to the rolling mill. 3. Repair process of equipment problems 3.1 Advantages and feasibility analysis of traditional repair mode Mechanical processing removal method. That is, the damaged layer on the surface of the archway is removed by machining online to process the mating surface, and the required elevation size is achieved by increasing the thickness of the bottom plate. After being repaired using this method, wear will appear after a period of use, and it will need to be machined again. Repeated machining will have an adverse effect on the strength and stiffness of the arch, and this method cannot fundamentally repair the wear. It needs to be machined on site after repair welding to process the joint surface. Large area surfacing can easily cause the arch to deform and bend due to thermal stress. And after repair, the joint surface and lining plate will wear again due to impact and corrosion. It cannot fundamentally solve the wear and tear, and the construction period is long. It consumes a lot of manpower, material and financial resources of the enterprise. Laser cladding. Compared with traditional surfacing, spraying, and electroplating, laser cladding has the characteristics of small dilution, dense structure, good combination of coating and substrate, many suitable cladding materials, and large changes in particle size and content. Therefore, the application prospects of laser cladding technology are very broad. However, the repair is often unable to be completed in a short time due to reasons such as high cost and long construction period. The comprehensive costs of maintenance labor costs, equipment transportation and machining costs required for traditional maintenance are higher than that of on-site repair. At the same time, the on-site space is limited, but the repair accuracy is relatively high. 3.2 Advantages and feasibility analysis of the on-site repair mode. On the premise that machining is not applicable, Fushilan polymer composite repair technology is used to repair on site. The chemical bond connection force formed after the curing of the repaired 2211F polymer composite material enables it to form excellent adhesion and compressive strength with the repaired metal parts, which can meet the requirements of the equipment to withstand various composite forces during operation. In addition, after repair using polymer composite materials, the mating surface can reach more than 90%, achieving a gap-free fit and avoiding the corrosion problem of the arch caused by the intrusion of cooling water. During repair, the corresponding repair process can be selected according to the wear degree of the arch and different matching parts. This time, the work roll lining plate and bending cylinder at the outlet of the operating side of the F3 rolling mill of this plant were repaired. ； The four repair surfaces of the work roll lining plate and the bending roller cylinder at the working side outlet are respectively repaired by the direct assembly process of applying materials, the jackscrew adjustment process, and the template repair process. Under the premise of ensuring accuracy, the wear problem of the rolling mill archway can be solved efficiently on-site. 4. Plan implementation process 1. First, measure according to the drawings and usage requirements, and then determine the wear amount again ； 2. Select the corresponding Fushi Blue rolling mill arch repair process based on the wear amount of the mounting surface of each bending roll cylinder. ； 3. Use oxygen acetylene for baking oil treatment ； 4. Use a polisher to polish the surface to remove the fatigue layer and high spots. 5. Use a sandblasting machine to roughen the surface and increase the bonding area. ； 6. Use absolute ethanol to clean the surface ； 7. Apply release agent to the roll bending cylinder, let dry and set aside. ； 8. Adjust the coating material so that the material thickness is slightly higher than the actual wear amount. ； 9. After the material is cured, review the size and remove excess material. 10. Mix the coating material again and assemble the roller bending cylinder. 5. Conclusion The on-site repair plan of Fushilan polymer composite material is used to repair the wear problem of the rolling mill archway, which solves the long-term problem that the wear of the rolling mill archway cannot be repaired quickly on site. According to several years of experience in repairing the rolling mill archway, the main cause of the damage to the archway is the mating surface problem. The repaired archway using Fushilan polymer composite material can on the one hand meet the strength requirements of the archway, and on the other hand, it can achieve a gap-free fit between the two to avoid the recurrence of corrosion problems. This application once again proves that Fushilan polymer composite technology can be well applied to the problem of rolling mill archway wear.