The liquid preparation is emulsified highly saponified oil, which has excellent lubricity, cooling property and annealing cleaning property. It can be used for process lubrication in large and medium-sized cold rolling mills, and is particularly suitable for plastic rolling mills and cold continuous rolling mills.

When in use, the rolling fluid needs to be prepared into an emulsion with soft water or tap water at the required concentration. The high-speed rolling fluid in the rolling fluid can be used on wide cold-rolled plastic rolling mills with a width of over 450mm or on cold continuous rolling mills with a rolling speed of over 250 meters per minute. It has high extreme pressure resistance and lubricity. Therefore, a pressure-resistant and heat-resistant lubricating film can be formed on the surface of the steel strip and the roll, thereby reducing the friction coefficient, increasing the corresponding rolling force, maintaining the good surface flatness, uniform thickness and brightness of the steel strip.

Rolling fluids can be classified into hot rolling fluids and cold rolling fluids according to the processing technology. Hot rolling and cold rolling: Rolling above the recrystallization temperature of metals is called hot rolling. Rolling below the recrystallization temperature of metals is called cold rolling (this article mainly discusses the rolling fluids of cold rolling).

The effect of cold rolling fluid

Lubricate the rolls and steel strips, reduce the external friction between the rolled metal and the rolls, thereby lowering the wear of the rolls, reducing the total rolling pressure and energy consumption, increasing the pass reduction rate, reducing the number of rolling passes, and enhancing the rolling speed.

2. Fully cool the rolling deformation zone. By taking advantage of the cooling effect of the stainless steel rolling fluid, the softening of the rolls and the change in roll shape can be prevented, making the rolling process stable. This is conducive to strictly controlling the product accuracy and plate shape, as well as the accuracy and surface finish of the strip after rolling.

3. Clean the rolling area and the surface of the steel strip to prevent mechanical scratches on the surface of the rolls and the steel strip. At the same time, ensure that a layer of oil film adheres to the surface of the steel strip after rolling, which is beneficial for rust prevention during the subsequent turnover process.

Maintenance of cold rolling fluid

In the application process of rolling fluid, in addition to choosing high-quality rolling fluid products, it is also necessary to scientifically and reasonably implement the "Ten Maintains" lubrication management to regularly monitor and maintain the rolling fluid, ensuring that all indicators of the rolling fluid remain within the normal range, thereby achieving the best lubrication effect

①Keep the pH value between 5 and 7

The pH value has a certain impact on the stability of emulsions. If the PH is less than 5, the particle size of the emulsion will increase, and the emulsion will be unstable. If the PH is greater than 8, the particle size will decrease, making lubrication difficult during cold rolling.

②Maintain the electrical conductivity ≤400 us/cm

The electrical conductivity reflects the amount and changing trend of inorganic salt components in the emulsion. Under normal circumstances, the pH value remains constant, and the electrical conductivity increases slowly with the extension of the rolling cycle. However, if the PH and conductivity suddenly rise simultaneously, it indicates that alkaline substances and their salts have entered the emulsion. If the PH suddenly drops and the conductivity rises, it may be that inorganic acids or their salts have entered the emulsion.

③Keep the oil concentration between 3% and 5%

Oil concentration refers to the total concentration of oil in the rolling emulsion, including rolling oil and miscellaneous oil. Sometimes it is also called the concentration of the emulsion, that is, the percentage concentration of effective rolling oil contained in the emulsion. During the rolling process, the oil content is constantly decreasing, generally ranging from 2% to 3%. So when the amount is lower than this, oil should be replenished to maintain its lubricating capacity.

④Keep the temperature between 45 and 60 degrees Celsius

The temperature of the emulsion is too low, which is not conducive to lubrication and is also prone to bacterial growth. If the temperature of the emulsion is too high, it is not conducive to cooling and may also affect the stability of the emulsion.

⑤Maintain the saponification value at 120-200 mgKOH/g

The saponification value refers to the number of milligrams of potassium hydroxide required to saponify 1 gram of sample oil. The saponification value can be used to determine the content of oiliness agents such as grease or synthetic grease in the rolling oil. A low saponification value indicates a high content of mixed oil and poor lubricity of the emulsion, while a low saponification value suggests good lubricity.

⑥Maintain the acid value ≤30 mgKOH/g

Acid value refers to the number of milligrams of potassium hydroxide required to neutralize the acidic substances in 1 gram of oil. The determination of free fatty acids can determine the decomposition amount of oil in emulsions. Free fatty acids are beneficial to the lubricating effect of emulsions, and their content should not be too low. However, if the content is too high, it may cause difficulties in degreasing the steel strip. When it suddenly rises, it indicates that there is bacterial growth in the emulsion.

⑦Maintain the ash content ≤500mg/L

The ash in the emulsion mainly comes from inorganic salts or iron powder. With the increase of rolling time, the ash content gradually increases. The lower the ash content of the emulsion during rolling, the better. Due to the high ash content, it increases mechanical wear, reduces the lubricity of the emulsion, and also affects the cleanliness of the plate surface after annealing.

⑧Keep the iron content ≤300mg/L

The iron content in the emulsion mainly comes from the metallic iron powder it comes into contact with. Iron in the emulsion mainly exists in the following forms: Fe, Fe3O4, FeO, Fe2O3 and iron soaps. A certain iron content promotes lubrication, but an excessively high iron content will cause excessive residue on the plate surface, affecting the subsequent processing procedures.

⑨Keep the chlorine content ≤25ppm

The emulsion itself does not contain chlorine, but in the previous process of acid washing during steel plate rolling, a certain amount of chloride ions will remain on the surface of the steel plate. An increase in chloride ion content indicates that there is a large amount of residue after acid washing, which cannot be purging thoroughly and is prone to acid corrosion. Therefore, detecting the chlorine content of the in-use emulsion is of great significance for controlling the quality of the board surface.

⑩Keep bacteria <105 and mold <103

If impurities of oil are mixed into the emulsion system and the equipment is shut down with the emulsion not circulating, and the temperature drops below 45℃, bacteria and mold will grow rapidly, causing the emulsion to become rancid, its PH to drop, and its performance to be damaged, which in turn affects the smoothness of the plate surface and its anti-rust performance.

The on-site maintenance of cold rolling fluid in the later stage is the most crucial factor affecting the actual application of emulsion. Standardized and strict on-site emulsion management and maintenance are the foundation for giving full play to the performance indicators of rolling oil.

Precautions for using rolling fluid

1. Regularly remove the floating oil layer and dirt on the surface of the liquid tank, as well as the emulsion channels and collection tanks. The filter should be cleaned regularly, and new liquid should be replaced or replenished on a regular basis according to the usage of the emulsion. When in use, uneven emulsion spraying or nozzle blockage often occurs. The reasons are that the nozzle aperture is too small, the oil-water mixture separates, the pipeline is too long, and the pipeline insulation is poor. The rubber in the pipeline ages due to contact with the oil.

2. Before cold rolling, the residual acid on the surface of the rolled piece should be thoroughly cleaned and the surface should be dried. Residual acid can cause the emulsion to demulsify, not only affecting the lubrication performance but also resulting in emulsified corrosion spots. When rolling thin strips, it may even lead to "perforation".

When preparing the emulsion, the concentrated liquid must be poured into water and stirred with compressed air to ensure the emulsion is uniform. When preparing emulsions, local water quality should be taken into account, such as the turbidity of water and the content of acidic and alkaline ions, which can affect the quality of the emulsion. During use, the quality of the emulsion should be regularly inspected, such as concentration, stability, corrosion resistance, PH value, bacterial content, etc.

4. The amount of emulsion used should be determined based on the rolling speed. For high-speed cold rolling mills, the emulsion consumption is approximately 700mL/min per meter of rolled piece, and it is sprayed onto the roll surface at a pressure of 300-500 kpa. In summer, the usage temperature is 25℃ to 35℃. In winter, after the machine stops and before starting up, the emulsion should be heated to 40℃ to 50℃. When the rolling mill is shut down, it is best for the emulsion circulation system to circulate for one hour every day to prevent the growth of bacteria or algae in the emulsion.