In the production of double-sheet foil, the rolling of aluminum foil is divided into three processes: rough rolling, intermediate rolling, and finishing rolling. From the perspective of technology, it can be roughly divided from the thickness of the rolling exit. Or equal to 0.05mm is rough rolling, the exit thickness is between 0.013~0.05mm is medium rolling, and the single finished product and double rolled finished product with exit thickness less than 0.013mm is finish rolling. Rough rolling is similar to the rolling characteristics of aluminum sheet and strip. The control of thickness mainly depends on rolling force and post tension. The processing rate of rough rolling is very small. Its particularity mainly has the following aspects:
1. Aluminum strip rolling. To make the aluminum strip thinner mainly depends on the rolling force, so the automatic control method of the plate thickness is based on the constant roll gap as the main control mode of AGC, even if the rolling force changes, the thickness can be obtained by adjusting the roll gap at any time to keep the roll gap at a certain value Consistent sheet and strip. From aluminum foil rolling to medium finish rolling, because the thickness of the aluminum foil is extremely thin, it is easier to increase the rolling force during rolling to make the roll elastically deformed than the rolled material to produce plastic deformation. The elastic flattening of the roll is impossible. Neglected, the spring rolling and flattening of the roll determines that in the aluminum foil rolling, the rolling force can no longer play the same role as rolling the plate. Aluminum foil rolling is generally rolled without roll gap under constant pressure conditions, and the thickness of the aluminum foil is adjusted. It mainly depends on the adjusted tension and rolling speed.
2. Stack rolling. For ultra-thin aluminum foil with a thickness less than 0.012mm (thickness is related to the diameter of the work roll), due to the elastic flattening of the roll, it is very difficult to use the single-sheet rolling method, so the double-rolling method is adopted. The method of adding lubricating oil between two sheets of aluminum foil and rolling them together (also known as stack rolling). Stack rolling can not only roll out extremely thin aluminum foil that cannot be produced by single sheet rolling, but also reduce the number of broken strips and improve labor productivity. Using this process, single-sided smooth aluminum foil of 0.006mm to 0.03mm can be produced in batches.
3. Speed effect. During the aluminum foil rolling process, the phenomenon that the thickness of the foil material becomes thinner with the increase of the rolling degree is called the speed effect. The explanation of the speed effect mechanism still needs to be studied in depth. The reasons for the speed effect are generally believed to have the following three aspects:
a. The friction state between the work roll and the rolling material changes. With the increase of the rolling speed, the amount of lubricating oil brought in increases, so that the lubrication state between the roll and the rolling material changes. The coefficient of friction decreases, the oil film becomes thicker, and the thickness of the aluminum foil decreases accordingly.
b. Changes in the rolling mill itself. In a rolling mill with cylindrical bearings, as the rolling speed increases, the roll neck will float in the bearing, so that the two interactively loaded rolls will move toward each other.
c. Processing softening when the material is deformed by rolling. The rolling speed of the high-speed aluminum foil rolling mill is very high. With the increase of the rolling speed, the temperature of the rolling deformation zone increases. According to calculations, the metal temperature in the deformation zone can rise to 200 ° C, which is equivalent to an intermediate recovery annealing, thus causing Work softening of rolled materials.