Aluminum and aluminum alloy bottle cap material is a new type of bottle cap sealing material, which not only has the characteristics of being beautiful and easy to open, but also has the function of preventing counterfeit goods. Therefore, it has been widely used for beverage bottles, wine bottles, cosmetics bottles, medicine bottles,etc.
8011 color coated aluminum foil is a main type of aluminum foil for bottle cap, featuring good deep drawing performance, low earing rate and certain strength after baking in the lid-making process. The main alloying elements of 8011 aluminum alloy are Fe and Si, and the rest are trace impurity elements.
Its specific production process is smelting-casting-soaking-hot continuous rolling-cold rolling-intermediate annealing-cold rolling-leveling-slitting or cross-cutting-packaging. Melting and casting mainly control the content and ratio of alloying elements, the heating temperature is 500±5°C for soaking, and the holding time is not less than 20h.
The cold rolling deformation of 8011 aluminum alloy in H16 temper must be greater than 40% at least. In order to obtain an aluminum foil sheet with a small earing rate(<3%), it is necessary to adjust the process to increase the proportion of annealed texture (cubic texture) in the finished plate to offset the excess rolling texture in the aluminum sheet.
As an Al-Fe-Si alloy, the Fe/Si ratio affects the earing behavior of the 8011 aluminum foil. The earing rate of the high-silicon and low-iron alloy is very small. But with the increase of Fe content and the decrease of Si content (Fe/Si ratio increases), the deformation texture develops more strongly, which will increase the 45-degree direction earing during deep drawing of 8011 bottle cap material.
The deep drawing performance and the earing rate of the 8011 h16 have a great relationship with the soaking process, the microstructure of the hot finish rolling and the subsequent intermediate annealing process. Select a reasonable intermediate annealing process and an appropriate cold working rate to seek a balance between the cubic texture and deformation texture of the alloy while ensuring that the alloy sheet has the strength required by the standard, so as to obtain good deep drawing performance and baking resistance.
Through a large number of process test optimization and industrialized large-scale production practice verification, we have formed the production process of 8011 h16 golden aluminum sheet for bottle cap.
Haomei Aluminum has determined the chemical composition control range of 8011 aluminum alloy, and the hot final rolling temperature. At the same time, an intermediate annealing process of 320 degrees Celsius and a cold rolling processing rate of 52% compatible with the intermediate annealing process are adopted.
Using the above-mentioned optimized production process, we can obtain a 8011 golden aluminum foil with the tensile strength of 145~185MPa, elongation≧1%, earing rate ≦3% and surface roughness ≦0.4um. After baking at 210 degrees Celsius for 12 minutes and continuous baking for 5 times, the tensile strength of the 8011 aluminum foil is ≧110MPas and the elongation is ≧2%.