The quality control technology in aluminum rolling process is very important to the current production enterprises. We now use the raw material rolling technology is to follow the mid-1970s Shanghai aluminum factory taught down mature rolling technology (at that time this technology is a relatively advanced production technology), from aluminum ingot and Angle material into the furnace to the finished aluminum strip factory, series aluminum processing rolling technology can be fully used and play, through more than 30 years of production practice and application, Without replacing the existing production equipment, it is very important to improve the rolling process technology and find and solve the common problems in production. According to the established rolling process of raw materials, it shall include melting, casting, hot rolling, cold passing and finishing rolling.
1. Smelting
The raw material smelted by our company is aluminum ingot and Angle material. Before the raw material is put into the furnace, I think it is necessary to inspect the diagonal material, mainly to check the impurity in the diagonal material for sampling, followed by the diagonal material for water content in the furnace, and never throw a block containing water Angle material into the furnace. After years of problem investigation and discovery, Water in corner material is one of the causes of quality problems such as bubbles.
In practice, I realize that in the smelting process, it is necessary to pay attention to the problem of degassing and slag discharge. If the degassing and slag discharge are not good, the product to the back road, or the finished product to the user, there will be subsequent products with bubbles, highlights, white silk and many other quality problems. The solution I adopted was to blow nitrogen into the liquid aluminum through a hollow tube. If it was handled well, the quality problems such as bubbles, bright spots and white silk would be eliminated.
In order to improve the water yield, after liquid aluminum reaches a certain temperature, continue to put a certain number of Angle material block into liquid aluminum, under the premise of temperature permitting, Angle material will quickly melt into liquid aluminum, saving time and material, has not burned, is a good way to improve economic benefits, but, to pay attention to the problem is, also to do a good job of gas and slag removal work, Otherwise there will be product peeling phenomenon.
Smelting in accordance with the technical requirements to do, product quality problems will be eliminated.
2. Casting
After the liquid aluminum has been stationary for a certain amount of time, it can be cast. At this time, the mold must go through safety inspection, operate according to the operating rules, tilt the mold to a certain Angle, and pour the liquid aluminum into the mold slowly, not too fast. Too fast easy to cause liquid aluminum in the inclusion of gas can not be discharged, resulting in the density of billet less than 2.7×103Kg/m3 (loose structure), its strength is lower than sb = 80 ~ 100MPa, especially after rolling to the subsequent processing products will appear a variety of quality problems. The filling after one casting should be carried out timely. Before the casting block is not hardened, the liquid aluminum should be poured into the concave filling to ensure that the billet size meets the requirements of the process sheet.
3. Hot rolling
After the surface layer of both sides of the cast block is cut off, the cast block billet with high temperature must not be used for the first rolling of the mill, because the hot rolling process will spray emulsion oil to both sides of the rolled billet at the same time to achieve the effect of lubricating the roll surface. If the billet temperature is too high, when the billet enters the roll, because the upper and lower planes do not contact the isothermal and equal amount of emulsion oil at the same time, The cold plastic deformation strengthening degree of the whole billet is not the same. The billet rolled from the middle of the roll is warped upward rather than straight forward, forming a roll shape, and the head is connected to the tail of the billet being rolled. This is the sticky roll. Because the blank in this case is thick, there is no tool to cut it. Unlike other metal products, aluminum products cannot use gas cutting, which is very tricky. And is often formed in a few seconds, the operator is more difficult to control, the only preventive measure is not to use too hot billet.
Hot rolling generally after many rolling, rolling, in the product can not touch the ground, once there are impurities stick on, very difficult to find, the formation of products will appear black silk, bright spots, etc., if scratched, there will be scratches, and generally is the follow-up product after coloring, oxidation will be found, so the production should be very careful.
4 Cold pass aspect
After cooling, continue rolling on the product in process, at this time to adjust the roll down, because cold rolled aluminum strip deformation process has a basic requirement, along the width of each part of the longitudinal extension. Pressure such as uneven distribution, strip width up and down the narrow strip will be the corresponding extension of uneven, resulting in the internal stress between the narrow strip. When the internal stress of the narrow strip is large enough, it will cause the warping of the strip, that is, the wave. The quality of the strip is the warping degree of the fingerboard strip. Cold rolling production of rolling strip blank plate shape requirements are: the same plate difference is small, convex, longitudinal difference is appropriate. The control of the same plate difference is the key to the shape control of the blank plate. To the finishing rolling, you can increase the tension to adjust the situation, but in the cold pass, there is no tension adjustment, you can only use fine control down control rolling.
Cold pass is divided into two ways, now we are using serial-type flow rolling, the middle with guide roller platform connected, labor saving, the disadvantage is that the operation requires high consistency, pressure adjustment technology is strong, need to be trained to work.
5. Finishing rolling
Mainly to control the thickness, rolling must master the thickness change, accurate and timely measurement of thickness, according to the central value to master the production thickness measurement and regulation, as far as possible to make the thickness of the aluminum strip in the center of both sides of 0.01 mm, fluctuation of more than 0.01 mm, should be adjusted.
6. Temperature control of lubricating materials
Process lubrication system is a lubrication and cooling medium system that provides certain pressure, flow rate, temperature and cleanliness for the rolling mill. Its main function is to reduce the temperature rise of the strip in the rolling process, provide sufficient lubrication, prevent metal scrapes and wear of the roll, and strip defects and impressions.
After years of experiments, my colleagues and I changed the original practice of oil lubrication, using emulsion oil lubrication, which not only saves costs, but also does not pollute the environment, and the product surface finish also meets customer requirements, but it needs to be kept in a certain temperature range in the rolling process, too high or too low temperature will affect the rolling product effect and product quality. Different mills have different temperatures, up to 60 degrees.
The above is engaged in aluminum rolling raw material worker leadership work in nearly 30 years a little technical summary, mainly a little practical experience report. Of course, in the scope of my supervisor's work, there are such as metal rolling workers, metal extrusion workers, maintenance electricians, fitters, heavy lifting, turning and other jobs, similar technical summary is no longer one by one.
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