Aluminum foil is a type of aluminum rolling material. Aluminum foil is mainly designed for thickness, and aluminum products with a thickness less than 0.2mm are usually referred to as aluminum foil in the industry. The edges are usually longitudinally cut and delivered in rolls. Aluminum foil is a soft metal film that not only has the advantages of moisture resistance, airtightness, shading, wear resistance, fragrance retention, non-toxic and odorless properties, but also has an elegant silver white luster, making it easy to process beautiful patterns and patterns of various colors.

According to thickness, aluminum foil can be divided into double zero foil, single zero foil, and thick foil. Double zero foil refers to a foil with two zeros after the decimal point when its thickness is measured in millimeters (i.e. thickness<0.01mm); Similarly, single zero foil refers to a foil with a zero after the decimal point measured in millimeters (0.01mm ≤ thickness<0.1mm); Thick foil refers to aluminum foil with a thickness between 0.1mm and 0.2mm.

Generally speaking, double zero foil is mainly used for food packaging, cigarette packaging, electronic optical foil, etc; Single zero foil is used for some food packaging, drug packaging, electronic circuit signal shielding, air conditioning foil, etc; Thick foil is mainly used for air conditioning foil, container foil, building decoration, and industrial purposes.

In 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 from the thickness of the rolling outlet. The general classification method is that the outlet thickness is greater than or equal to 0.05mm, which is rough rolling. The outlet thickness is between 0.013 and 0.05, which is intermediate rolling. Single sheet products with an outlet thickness less than 0.013mm and double rolled products are precision rolling. The rolling characteristics of rough rolled aluminum plate and strip are similar, and the control of thickness mainly relies on rolling force and post tension. The thickness of rough rolling processing rate is very small, and its rolling characteristics are completely different from the rolling of aluminum plate 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, so 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 rolling aluminum foil to medium precision rolling, due to the thin thickness of aluminum foil, increasing the rolling force during rolling makes it easier for the roller to generate elastic deformation than plastic deformation of the material being rolled. The elastic flattening of the roller cannot be ignored. The elastic flattening of the roller determines that in aluminum foil rolling, the rolling force no longer plays the role of rolling the plate. Aluminum foil rolling is generally done under constant pressure conditions without rolling gaps, Adjusting the thickness of aluminum foil mainly depends on the adjusted tension and rolling speed.

(2) Stacking. For aluminum foils with a thickness less than 0.012mm (the thickness is related to the diameter of the work roll), due to the elastic flattening of the roll, it is very difficult to use single sheet rolling. Therefore, a double rolling method is adopted, which involves adding lubricating oil between the two aluminum foils and then rolling them together (also known as stacking rolling). Stacking rolling can not only produce aluminum foil that cannot be produced by single rolling, but also reduce the number of strip breaks and improve labor productivity. By using this process, single-sided smooth aluminum foil of 0.006mm~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 rolling process is called the 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 work roll and the rolling material changes, and as the rolling speed increases, the amount of lubricating oil introduced increases, resulting in a change in the lubrication state between the 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, as the rolling speed increases, the roll neck will float in the bearing, causing the two interacting loaded rolls to move towards the direction of being close to each other.

3) The softening of materials during rolling deformation. The rolling speed of high-speed aluminum foil rolling mill is very high. As the rolling speed increases, 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 softening phenomenon of the rolled material during processing.

Article source: Internet

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