[China Aluminum Industry Network] (1) Pinholes. Pinholes are the primary drawback of aluminum foils. It was originally guessed that the size of the dust in rolling oil, rolling oil, and even the air reaching 6μm into the roll gap can cause pinholes, so that 6μm aluminum foil without pinholes is impossible, and it can only be assessed with how much and how large. Because of the improved rolling conditions of aluminum foils, especially the useful filtration of dustproof and rolling oils and the convenient setting of the roll change system, the number of pinholes in aluminum foil is increasingly dependent on the quality of the metallurgy of the material and processing defects, since pinholes are usually With the drop of material defects, it is difficult to find the correspondence with the original defects. It is generally believed that pinholes are primarily related to gas content, impurities, compounds and segregation of components. The adoption of useful aluminum liquid purification, filtration, and grain refinement all contribute to the reduction of pinholes. Of course, the use of alloying techniques to improve the hardenability of the material also helps to reduce pinholes. High-quality hot-rolled 6μm aluminum foil pinholes can be less than 100/inch. When the material is better, the pinhole of 6μm aluminum foil is less than 200/?. During the aluminum foil rolling process, other elements or many of the other pinholes are even catastrophic. Thousands of pinholes per square meter are not uncommon. The useful filtration of rolling oil, the short-term replacement of the rolls and the dust-proof method are all necessary conditions to reduce the pinholes of the aluminum foil. With the large rolling force, the small tension rolling will also help to reduce the pinholes.
(2) Roll, roller, and uneven gloss. It is mainly the aluminum foil defects caused by the roller, divided into three types: point, line, and surface. The more obvious three-cycle feature is presented. The main reasons for this disadvantage are: incorrect grinding of the roller; damage to the roller due to foreign objects: inadvertent printing defects; flaws in the roller; impact between the rollers, slippage, etc. All the elements that can cause damage to the roll surface can damage aluminum foil. Because aluminum foil rolling roller surface finish is very high, subtle gloss unevenness will also affect its appearance. Regular finishing mills, keeping the mills clean, ensuring the normal operation of the rollers, regular roll changes, and reasonable grinding are the basic conditions for ensuring uniform appearance after rolling aluminum foil.
(3) Wrinkle. Because of the poor shape of the plate, wrinkles are formed when the aluminum foil is coiled or opened, and the nature thereof is a lack of tension to flatten the foil surface. Regarding the equipment of tension dimension 20MPa, the foil shape of the foil surface must not be greater than 30I. When it is greater than 30I, it must wrinkle. Because the aluminum foil usually receives more tension than the subsequent processing when rolling, some only show poor plate shape during rolling, including incorrect roll grinding, incorrect roll shape, poor shape of the incoming plate, and incorrect adjustment of the plate shape.
(4) bright spots, bright spots, bright spots. Due to the improper use of double oil, the bright spots, bright spots, and bright spots on the double-skin surface are mainly due to the lack of strength of the double oil film or uneven roll surface, which leads to uneven rolling and the appearance of a skin or foreign material. . Choosing a reasonable double oil, keeping the incoming material clean and evenness of the roll surface is a useful way of dealing with this type of disadvantage. Of course, it is also necessary to change the amount of reduction and select excellent aluminum plates.
(5) Thickness difference. Thickness is difficult to control is a feature of aluminum foil rolling, 3% of the thickness difference may not be difficult in the production of the plate, but in the production of aluminum foil is very difficult. The reason is that the thickness is thin, and other trace conditions can affect the temperature, oil film, and oil and gas concentration. Rolling aluminum foil can reach hundreds of thousands of meters. The rolling time is as long as 10 hours. With the extension of time, the thickness difference is very easy to construct, and the thickness adjustment method has only tension speed. These elements all constitute the hard control of aluminum foil rolling. Therefore, the actual manipulated thickness difference is within 3%, and many conditions are needed to ensure that it is quite difficult.
(6) Oil pollution. Oil stain refers to the remaining oil on the outer surface of the aluminum foil after rolling, that is, oil other than the rolling oil film. These oils are usually thrown at the roll neck or at the exit of the mill, splashed, and dripped on the foil surface, and are dirty and have a messy composition. The outer surface of the aluminum foil is more oily than other rolled materials. First, because most of the aluminum foil finished products are used as decoration or packaging materials, they must have a clean appearance. The second is that the thickness of the aluminum foil is thin, and it is easy to form a bubble when annealing afterwards. And because of the large amount of oil in the place where it forms too much residue, it affects the application. How much is the disadvantage of oil pollution is an important indicator to evaluate the quality of aluminum foil.
(7) Water spots. Water spot refers to the appearance of water droplets on the surface of the foil before rolling and white traces formed after rolling. When it is fine, it will affect the appearance of the foil surface. When it is severe, it will lead to a broken belt. The water spot is formed by the presence of water droplets in the oil or drops of water on the surface of the foil in the rolling mill. Manipulation of the water in the oil and the water source is a special method to prevent water spots.
(8) Resonance marks. The oscillating mark refers to the periodic transverse wave of the aluminum foil. There are two kinds of chattering causes: one is that the roller is formed during grinding and the cycle is about 10~20mm; the other is that when the rolling is performed, the oil film discontinuously oscillates and often occurs in a speed zone with a period of 5 cycles. ~10mm. The bottom edge of the chatter marks is the lack of oil film strength and can usually be eliminated by using an improved smooth condition.
(9) Tension line. When the thickness reaches 0.015mm or less, a parallel stripe is formed in the longitudinal direction of the aluminum foil, commonly called a tension wire. The tension line distance is about 5~20 mm, the smaller the tension, the wider the tension line and the more obvious the stripes. When the tension reaches a certain value, the tension line is subtle or even missing. The smaller the thickness is, the greater the possibility of occurrence of tension threads is, and the possibility of double tension rolling is greater than that of single sheets. Increasing tension and roll roughness is a useful way to reduce or eliminate tension lines, and large tensions must be based on an outstanding plate shape.
(10) Open seams. Slotting is a unique disadvantage of foil rolling, which cracks straight in the longitudinal direction during rolling, often accompanied by metal wire. The bottom edge of the seam is discounted on the side of the entrance, which often occurs in the center, mainly because of guessing the loose center or poor roll. Severe slits cannot be rolled, and subtle slits are split at the time of future slitting, which often constitutes a lot of waste.
(11) Airway. At the time of rolling, it was crushed in strips, with a droplet-like curve at the margin. It had a certain width, and the mild airway was not crushed. It was white strips with dense pinholes. The presence of a pinhole in the front and rear ends of crushed aluminum foil is the primary symbol of airway and other shortcomings. Air channels originate from the material. It is very important to select materials with low gas content as aluminum blanks.
(12) Coiling shortcomings. The disadvantages of rewinding mainly refer to loose or loose inner tightness. Because aluminum foils have limited tension, winding hard rolls can be difficult. It is desirable to obtain a roll with tight outer core, and sufficient tension is a condition that constitutes a certain tension gradient. Therefore, the quality of coiling ultimately depends on the shape of the board. The outer coils of the inner shaft form a horizontal edge, and the coils of the inner coil form an ellipse, which will affect the future processing.
Although there are many disadvantages in aluminum foil rolling, the main performances are: pin holes, roll eyes, slits, and air passages characterized by holes; oil stains, uneven gloss, vibration marks, tension lines, and water that are characterized by appearance conditions. Spot, bright light spot; to affect the post-process processing of the plate shape, wrinkling, discounting, coiling bad; thickness difference characterized by the scale. In fact, the unique disadvantage of aluminum foil is only pinholes, and the other shortcomings are the same, but the performance is different or the needs are different.
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