The aluminum coiling drum that appears from time to time in the production of aluminum foil rolling mills will affect the appearance and use of aluminum coils. So, what precautions should be taken in this case?
(1) The crown of the high-speed aluminum foil mill roll is different between the rising speed stage and the positive: normal operation, and the roll temperature is relatively low when the speed is increased. The crown is also small, especially for new rolls, which have a relatively small crown. From the speed up to the thickness of the scraping mark, the panel-shaped lamp is broken and straight (矽) to the bottoming address of the juice roll. When the convexity is small, the speed increasing process is loose on both sides of the material. To establish a certain thermal convexity, the bottom of the material needs to be too long to be flattened, and the sides of the material are too loose to form a drum; in the flattening roller pressure Under the action of the action, the aluminum foil on the bottom is affected by the drum material at the bottom, and a large number of drums will be generated, which not only makes the bottom speed increase difficult, but also affects the rate of the material due to the inability of the bottom material to be used. When the crown is large, there will be a significant improvement in the speed-up quality. However, because of the high thermal crown of high-speed rolling, the middle drum is often formed because the middle plate is too loose.
Therefore, according to the shape of the plate at the outlet side, the roll crown is adjusted in time to ensure the quality of the bottoming and the shape control during normal rolling, which is one of the measures to prevent such drumming.
(2) The so-called shape parameter refers to the set target shape curve: the typical target plate is a parabola, that is, the secondary line of the middle and the loose side, and if necessary, can be corrected as needed. The value of the plate shape parameter is determined according to the shape of the online exit plate and the production condition of the lower channel. If the setting of the plate shape parameter causes the material to be convex, and the transition to the plate shape parameter of the next pass is not appropriate. The deformation zone of the convex man is relatively long, the deformation heat in the middle of the roll is large, the heat of the roll is relatively large, and the middle plate shape of the material is loose, and the middle drum phenomenon may occur.
Therefore, the design of the plate shape parameters must ensure that the door plate shape is flat and at the same time ensure that the middle portion is slightly tighter than the edge portion, that is, it is kept at a medium height, and a reasonable transition of the plate shape parameters between the passes is also considered.
(3) When the high-speed aluminum foil rolling mill is rough and medium-rolled, the deformation zone will generate large deformation heat. The cooling effect of the rolling oil is important for maintaining the roll type and stabilizing the rolling. If the injection pressure and flow rate of the cooling oil are insufficient, the cooling effect is affected, but in the actual production process, the pressure and flow rate of the cooling oil are monitored. Generally no problem. A lot of weather resistance is the mechanical filling of the nozzle of the oil filling or the mechanical failure of the oil pipe which is connected to the nozzle, such as falling off, rupture, etc., resulting in insufficient flow and pressure of the coolant in the working section, and the cooling effect is greatly reduced. The corresponding area is rolled high, the shape of the plate is loose and the drum is
Therefore, the spray effect of the nozzle should be checked regularly, once the drum is activated. Stop the machine in time to check the spray operation: this is one of the measures to prevent the drum.
(4) The actual aluminum foil rolling deformation zone is mostly in the form of mixed lubrication. The microprotrusion in the deformation zone is broken due to the contact pressure being too high, causing the metal to directly contact. At this time, the pressure in the deformation zone is borne by the fluid. In another part, the thickness of the oil film in the shape of the contacted microprotrusion is also reduced as the reduction ratio increases. Simultaneously. In the high-speed rolling state, a large amount of deformation heat will cause the deformation temperature to rise, the thermal motion of the lubricating oil molecules is intensified, and the directional adsorption is reduced. The oil film strength drops, and even the oil film breaks. The scratch on the metal surface begins to occur, and the absolute temperature at this time is called the critical failure temperature of the rolling oil. If the local temperature of the deformation zone exceeds the enthalpy, the boundary will rupture, causing direct contact with the metal surface, thereby increasing the friction factor, increasing the wear and increasing the temperature of the deformation zone, which further promotes the fracture of the oil film. The area percentage of the metal surface where direct contact occurs. It will increase rapidly, and the heat will accumulate rapidly there, causing the outlet material to change into a drum.
Process lubricants differ in their critical failure temperature T, and their temperature is related to the performance of the lubricating base oil and the additive ratio. The hearing film formed by the additive molecules has a high strength and can be cracked at a higher temperature, but the oil film strength and the critical failure temperature T formed by the different ratios of the additives are different. Reasonable preparation of rolling oil is very important to enhance oil film strength and increase rolling speed. Generally, the rolling oil is formulated according to the principle of high oil film strength, low viscosity, and low oil spot tendency. First choose the appropriate base oil (carbon chain between C10 ~ C14 0) and the appropriate proportion of additives (based on composite additives, ester 2% ~ 3%, alcohol 1% ~ 2%) should also be produced according to the factory The actual situation is adjusted. The performance parameters of the rolling oil are strictly controlled during the preparation process.
Based on the above analysis, before using aluminum foil rolling mill to roll aluminum foil, corresponding preventive measures can be taken to improve production and ensure the quality of aluminum coil.