A rolling mill is a pivotal piece of equipment in the metal rolling process, designed to complete the entire rolling production sequence. It encompasses main equipment, auxiliary apparatus, lifting and transport gear, as well as accessory tools. The core components of a rolling mill include rollers, a rolling mill housing, bearing packages, bearings, workbenches, rolling guides, rail chairs, roller adjustment devices, top roll balance mechanisms, roller change devices, driving units, cooling beds, finishing facilities with cold shears, bundling systems with bar counters, and wire tying machines, among others.
1.Uniform Deformation: The complex section pass, composed of four rollers, ensures that all components on the section are compressed simultaneously. This results in even deformation of the rolled piece, minimal speed differences around the section, and reduced internal stress.
2.Enhanced Product Capabilities: Rollers with smaller diameters (without the need for grooving) can be employed to produce products with higher legs and wider waists, maintaining straight inner sides on both legs—a feat challenging to achieve with ordinary two-high rolling mills.
3.Separate Adjustment of Leg and Waist Reduction: The ability to adjust the reduction of the leg and waist of the rolled piece independently simplifies the rolling mill's adjustment process during operation.
4.High Precision and Efficiency: Rolling machines for rebar offer high rolling accuracy, minimal roller wear, and lower energy consumption, contributing to cost-effectiveness and product quality.
The working environment of rolling mills is harsh, with rolling cooling water rapidly atomizing upon contact with red-hot billets, and iron oxide powder from the billet surface being sprayed around. This leads to significant impact on the mill frame archway through the bearing seat, causing varying degrees of corrosion and wear on the inner window surface and bottom surface of the frame archway. Effectively controlling and managing the gap between the mill stand and roll bearing seat becomes challenging, often exceeding management limits. An increase in mill housing clearance deteriorates the working conditions of the main drive system, resulting in large vibrations and impacts.
When the ingot is bitten, slippage is prone to occur, affecting plate shape control and significantly impacting product quality. Most mill housings are made of ordinary steel castings, which are susceptible to corrosion and wear over long-term service, degrading working conditions. Repairs are typically conducted via online machining, removing material to level the contact surface and compensate for expanded sizes by increasing lining plate thickness. However, this method does not alter the surface nature of the archway and can adversely affect its strength and stiffness after multiple machinings.
Manual arc welding can restore the expanded size of material removed after machining, but large-area arc surfacing on rigid structures may cause archway deformation, which is fatal and irreversible in factory production. Therefore, this repair method carries significant risks and is generally avoided.
To date, polymer composites offer a viable solution to mill housing wear. These repair materials exhibit superior adhesion, firmly attaching to metal substrates for long-term durability without falling off. They possess extremely high compressive strength, withstanding rolling forces up to 1900 tons without damage. The unique polymer structure provides excellent impact resistance, absorbing bearing seat impacts on the archway to prevent wear. Additionally, these materials offer good corrosion resistance, protecting the archway surface from cooling water erosion. Special materials are used to repair mill housing wear without material removal, preserving overall housing strength and stiffness and avoiding deformation caused by repair welding thermal stress. This approach resolves long-standing problems, providing a reliable and efficient maintenance solution.
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