Aluminum foil rolling is a process of cold rolling aluminum or aluminum alloy blanks (coil blanks) into foil material through a flat roller
The particularity of aluminum foil rollingIn the production of double foil, the rolling of aluminum foil is divided into three processes: rough rolling, intermediate rolling, and precision rolling. From a process perspective, it can be roughly divided based on the thickness of the rolled exit. The general classification method is that the exit thickness is greater than or equal to 0.05mm, which is rough rolling. The exit thickness is between 0.013 and 0.05, which is intermediate rolling. Single sheet and double roll finished products with an exit thickness less than 0.013mm are precision rolling. The rolling characteristics of rough rolling are similar to those of aluminum sheet and strip. The control of thickness mainly relies on rolling force and post tension. The processing rate of rough rolling is very small, and its rolling characteristics are completely different from the rolling of aluminum sheet and strip. It has the particularity of aluminum foil rolling, and its characteristics mainly include the following aspects:(1) Aluminum plate and strip rolling. The thinning of aluminum plates and strips mainly relies on rolling force. Therefore, the automatic control method for plate thickness is based on the constant roll gap as the main AGC control method. Even if the rolling force changes, adjusting the roll gap at any time to maintain a certain value can still obtain plates and strips with consistent thickness. When aluminum foil is rolled to medium precision rolling, due to the extremely thin thickness of the aluminum foil, increasing the rolling force makes it easier for the rolling roller to produce elastic deformation than plastic deformation of the rolled material. The elastic flattening of the rolling roller cannot be ignored. The elastic flattening of the rolling roller determines that the rolling force no longer plays the role of rolling sheet metal in aluminum foil rolling. Aluminum foil rolling is generally carried out under constant pressure conditions without roll gaps, and adjusting the thickness of the aluminum foil mainly depends on the adjusted tension and rolling speed.(2) Stacking and rolling. For extremely thin aluminum foils with a thickness less than 0.012mm (thickness size depends on the diameter of the working roll), it is very difficult to roll them using a single sheet rolling method due to the elastic flattening of the rolling rolls. Therefore, a double rolling method is adopted, which adds lubricating oil between the two aluminum foils and then combines them for rolling (also known as stacking rolling). Stacking rolling can not only produce extremely thin aluminum foils that cannot be produced by single rolling, but also reduce the number of strip breaks and improve labor productivity. Using this process, single sided glossy aluminum foils with a thickness of 0.006mm to 0.03mm can be produced in bulk.(3) Speed effect. The phenomenon of the thickness of aluminum foil becoming thinner with the increase of rolling schedule during the aluminum foil rolling process is called velocity effect.
The explanation of the velocity effect mechanism still needs further research, and the reasons for the velocity effect are generally believed to be the following three aspects:1) The friction state between the working roll and the rolling material changes. As the rolling speed increases, the amount of lubricating oil introduced increases, resulting in a change in the lubrication state between the rolling roll and the rolling material. The friction coefficient decreases, the oil film thickens, and the thickness of the aluminum foil decreases accordingly.2) Changes in the rolling mill itself. A rolling mill using cylindrical bearings will have the roll neck floating in the bearing as the rolling speed increases, causing the two interacting and loaded rolls to move in a direction that is close to each other.3) The processing softening of materials during rolling deformation. The rolling speed of high-speed aluminum foil rolling mill is very high. With the increase of rolling speed, the temperature in the deformation zone increases. According to calculations, the metal temperature in the deformation zone can rise to 200 ℃, which is equivalent to an intermediate recovery annealing, causing the processing softening phenomenon of the rolled material.
Principles for formulating aluminum foil rolling process① The determination of total processing rate refers to the total deformation degree of the foil material from recrystallization annealing to rolling out the finished product. Generally speaking, the total processing rate of the 1 series can reach over 99%, and some products of the 8 series can also reach this value. However, the total processing rate of aluminum alloy foil is generally below 90%.② The determination of pass processing rate is the core of the rolling process. For pure aluminum series products, the pass processing rate can reach 65%. For the first pass after annealing of the billet, it is not advisable to use a too high processing rate, usually around 50%.
Rolling thicknessThe thickness measurement methods for aluminum foil rolling mainly include eddy current thickness measurement, isotope ray thickness measurement, and X-ray thickness measurement. X-ray thickness measurement is the most commonly used method in aluminum foil production, especially in high-speed aluminum foil rolling mills. The thickness control methods during aluminum foil rolling include rolling force control, tension control, rolling speed control, tension/speed, speed/tension control.
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