During the rolling process, particularly cold rolling, to reduce friction between the roller and the rolled material, lower rolling force and power consumption, and facilitate material elongation, control the rolling temperature, and improve the quality of the rolled product, it is essential to introduce a lubricating and cooling fluid between the roller and the rolled material contact surface. This process is known as rolling process lubrication.
Cold rolling is typically obtained after hot rough rolling and finishing rolling, resulting in a thickness of2 to 4mm steel coils, pickled and annealed, are processed through a multi-roll mill (either reversible or continuous rolling) to produce thin plates ranging from 0.8mm to 0.01mm in thickness. Due to the high deformation resistance of cold metal, the rolling force of modern cold rolling mills has reached thousands of tons, while the rolling speed is close to 2500m/min. Clearly, during this high-speed deformation process, the metal generates a significant amount of heat energy due to the friction between internal metal molecules; on the other hand, the thinning (extension) of the rolled material inevitably causes relative motion between the roller and the surface of the rolled material.
The fundamental requirements for cold rolling lubricants are:
1. Appropriate oiliness ensures the formation of a boundary oil film under the rolling pressure, which in turn reduces frictional resistance and the resistance to metal deformation; it also minimizes the wear on the rolling mill rolls, extending their service life; and increases the reduction in the number of passes, saving energy consumption. However, it is important to consider that a certain level of friction between the rolling mill rolls and the steel is necessary to allow the steel to grip the rolls; a too low coefficient of friction will result in slippage. Therefore, the lubricating performance must be appropriate.
2. Excellent cooling capability, which can absorb the heat generated during the rolling process to the maximum extent, achieving constant temperature rolling to maintain stable roller shape, ensuring uniform thickness of the strip steel.
3. Offers excellent cleaning action for roller and strip surfaces, effectively removing impurities and dirt from external sources to enhance the surface quality of steel.
4. Excellent physical and chemical stability. During the rolling process, it does not undergo a chemical reaction with the metal, thereby not affecting the physical properties of the metal.
5. Excellent annealing properties. In the modern production of cold-rolled strip steel, to simplify the process, enhance labor productivity, and reduce costs, a production process is used for intermediate annealing that does not require degreasing and cleaning before annealing. This necessitates that the lubricant does not cause annealing corrosion due to its residue on the steel surface (i.e., the formation of spots on the steel surface).
6. Excellent filtration performance. To enhance the surface quality of steel, certain rolling mills employ high-precision filtration devices (such as diatomite) to maximize the removal of impurities from the oil. At this point, it is crucial to prevent the adsorption or filtration of additives in the oil to maintain the quality of the oil product.
7. Excellent oxidation stability and long service life.
8. Excellent rust resistance. Offers excellent anti-rust protection during short-term storage between processes.
9. Shall not contain substances harmful to human health or刺激性 odors.
The oil source is widely available, easily accessible, and cost-effective.
Hot Rolling Process Lubrication
Increasing the output of the hot rolling mill group, reducing consumption, and enhancing production efficiency is a crucial matter in the rolling process. Practices from various countries have proven that the use of hot rolling oil can significantly reduce roller wear, lower electricity consumption, improve the surface quality of steel plates, and increase production efficiency.
The following benefits can be obtained by using hot rolling (which has been proven by practice):
Improved the surface condition of the rolling mill rolls.
2. Reduced the unit consumption of rolling mill rolls.
The energy consumption has been reduced.
Improved the surface quality of steel strips.
5. Reducing rolling pressure facilitates the production of thin-gauge steel strips.
6. Facilitate the research of hot rolling theory.
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