Causes and solutions of rolling oil retention in aluminum foil products

Rolling oil retention in aluminum foil products

Rolling oil retention in aluminum foil products means that after the aluminum foil product has been rolled, rolled, passed, and annealed, there is still excess rolling oil remaining on the surface of the aluminum foil, which affects the use of the aluminum foil.

Reasons for retention of rolling oil in aluminum foil products

• (1) The surface of the products produced by the aluminum foil rolling mill is more or less oily. If the rolling oil sticks to the surface of the aluminum foil too much, it will cause the users of the products to be unable to use it, greatly reducing the yield and making the products unusable. The efficiency of the enterprise has been lost.
• (2) The aluminum foil rolling mill belt consumes rolling oil and increases the cost of the product. Excessive oil belt will cause serious stratification phenomenon when the coiling is tightened. If the string layer is caused in the middle pass, the upper edge of the finished product will not be cut during edge cutting, causing the aluminum foil to break. Too much oil in the middle pass will also have adverse consequences for double-pass rolling (also called stack rolling). A large amount of uneven oil will produce oil stains on the surface of the aluminum foil, and bulging and blistering will occur during double-pass rolling.
• (3) When the finished product is annealed, the residual rolling oil on the surface of the aluminum foil cannot be burned. The rolling oil remaining on the product will cause the aluminum foil roll to be unable to be opened, causing oil spots and adhesion. During annealing, the rolling oil will not be oxidized and burned, and decomposition, cracking, polymerization and oxidation reactions will occur to generate dendritic substances and deposit on the surface of the aluminum foil. Severe yellow and tan oil spots will not be included in the aluminum foil product standards. allowed to occur.
• (4) For finished aluminum foil that is not annealed, such as decorative foil, medicinal foil and other products, there are more stringent requirements for oil. Decorative foil and medicinal foil are composite foils. If there is a lot of oil, they cannot be composited. Medicinal foil tapes containing too much oil will have an impact on their heat sealing strength. When passing through the drying box, the oil will not burn completely and the compound will not be able to be used. The viscosity and acid value of aluminum foil rolling oil will affect the surface quality of aluminum foil.

Measures to be taken to remove oil on the surface of aluminum foil

We have realized in production practice that removing surface oil is a comprehensive management task, which involves all aspects of aluminum foil rolling, especially rolling oil management, equipment modification, process control, auxiliary improvement, etc. Let’s talk about our production experience and specific measures in removing surface oil from the above aspects.

Rolling oil management

• (1) On the premise of ensuring process quality, appropriately reduce the content of additives and lauric acid in the rolling oil and reduce the kinematic viscosity. Especially the content of lauric acid must be strictly controlled because of its strong adsorption capacity. The control method currently adopted by our factory is to dilute the rolling oil before sampling and analyzing it, and then rolling the finished product after passing the test.
• (2) When rolling the finished product, the oil pressure and flow rate of the rolling oil should be adjusted, and the temperature should be appropriately increased to reduce the viscosity of the rolling oil. Even a small amount of rolling oil on the surface is easy to volatilize. Regularly cleaning the residual oil and oil mist on the frame and purifying the oil tank can also effectively reduce the amount of oil on the surface of the aluminum foil.
• (3) It is impossible to remove all the rolling oil from the surface of the rolled aluminum foil. Therefore, there are strict requirements for the rolling oil of the aluminum foil rolling mill, especially for the base oil, additives and lauric acid. The adsorption strength and volatilization must first be considered. sex. The adsorption strength molecule is conducive to the formation of a strong single-molecule adsorption layer on the metal surface, with high oil film strength, which effectively inhibits direct contact between metals and adhesion in mixed or boundary lubrication conditions. Less active polar molecules can volatilize effectively at lower temperatures. Therefore, when aluminum foil rolled products contain a small amount of rolling oil, the adsorption strength and volatility must be taken into consideration.
• (4) Routine inspections of hydraulic oil and oil mist lubrication pipelines should be strengthened, easily damaged pipelines and seals should be replaced in a timely manner, and oils with lower viscosity should be replaced while ensuring the effectiveness of hydraulic oil and oil mist lubrication oil. will be better.

Improvement of oil removal device

The high-speed aluminum foil rolling mill runs fast and throws off a lot of oil. The rolling mill frame will also produce oil droplets due to oil vapor, which will drip onto the surface of the aluminum foil. Therefore, it is necessary to configure a good outlet oil removal device and adjust the appropriate air pressure to reduce the oil on the surface of the aluminum foil to a minimum. The outlet oil removal device indicates that it is impossible for the two oil removal air nozzles on the outlet oil removal device to remove all the rolling oil thrown from the upper support roll and the upper work roll. Therefore, an additional oil removal device should be added behind the outlet oil removal device. A duckbill blast removes oil. Duckbill blowing removes oil from the fan-shaped surface. The appropriate wind pressure and direction must be adjusted to obtain an aluminum foil product with a clean surface.

In addition, the high-speed aluminum foil rolling mill will produce a large amount of rolling oil mist during the rolling process. If the smoke exhaust device above the aluminum foil rolling mill frame is not effective, it will also cause the rolling oil mist to not be discharged well, thus causing Oil drips onto the surface of the aluminum foil. Therefore, the smoke exhaust device installed at the entrance and exit of the aluminum foil rolling mill must have sufficient suction power, the position of the suction port must be appropriate, and the movable baffle of the suction port must be adjusted appropriately, so as to achieve the ideal smoke exhaust effect.

Correct use of winding tension and flattening roller

Excessive coiling tension, poor aluminum foil plate shape, and improper setting of the flattening roller will cause rolling oil to be involved in the aluminum foil roll, resulting in uneven distribution of oil content.

• (1) The coiling tension should not be too large or too small, as long as the winding is tight and the end faces are neat. The flatness problem needs to be adjusted with the appropriate amount of rolling oil injection. Where the flatness on the surface is not good, there will be more rolling oil remaining. Where there are waves, it is caused by uneven heat of the roll and needs to be increased. The amount of rolling oil injection is used for cooling, and a good plate shape is of great help in reducing the amount of oil carried.
• (2) The given pressure of the flattening roller and the front and back position of the movable handle will affect the wedge area and void ratio of the aluminum foil roll. By controlling the pressure and front and rear position of the flattening roller well, the air in the wedge-shaped area between the aluminum foil roll and the flattening roller can be evacuated. The void ratio is not too small, and the requirements for the flattening roller can basically be met.

Reasonable selection of upper and lower support roller oil scrapers

The upper and lower support rollers of the aluminum foil rolling mill have oil scrapers. The oil scraper is composed of pneumatic mechanical principles and is equipped with oil scraper strips that can move laterally on the surface of the support roller. Whether the oil scraper is clean is also a factor affecting the oil on the surface of the aluminum foil. Choosing a harder material to make the bead will damage the support roller, and choosing a softer material to make the bead will not have a good oil scraping effect. Therefore, it is best to use materials with a hardness lower than the hardness of the support roller itself (the hardness of the support roller is generally between 65 and 75HS shore hardness) to make the scraper strip of the support roller.

Summary

Through the above analysis, the following conclusions can be drawn:

• (1) The viscosity, additives, and acid value content of the rolling oil used in the aluminum foil rolling mill have a greater impact on the annealing and degreasing of aluminum foil products.
• (2) The outlet oil removal device of the aluminum foil rolling mill plays a key role in the oil content of the product.
• (3) The correct use of winding tension and flattening roller is the basis for reducing the amount of oil on the surface of aluminum foil.
• (4) The oil scraping plates of the upper and lower support rollers of the aluminum foil rolling mill play a role in preventing the support rollers from throwing away oil and carrying oil.

For aluminum foil manufacturers, the phenomenon of rolling oil retention in aluminum foil products should have been encountered, but it is very rare to be able to completely summarize the problem for reference by peers.

Huawei Aluminum has encountered many problems in the aluminum foil production process, but we treat problems with a professional and dedicated attitude, solve problems, and share problems. We believe that our products will inevitably become the best quality and lowest cost products on the market.