1 Traditional Degreasing Method On The Surface Of Aluminum Strip
Since the introduction of rolling mill oil in the early metal plate and strip rolling, the problem of degreasing has arisen. So far, the degreasing methods can be summarized as follows:
(1) Degreasing The Rubber Mill Roll
The squeezing roll degreasing is the most primitive degreasing method. Its main component is to use the upper and lower rubber rolls to squeeze to remove the oil on the belt surface to achieve the purpose of degreasing. The selection of rubber is generally oil-resistant nitrile rubber. The biggest advantage of rubber is that it is cheap. However, because the rubber roll itself cannot absorb oil, its biggest defect is that the oil is not squeezed cleanly, especially when the rolling mill speed is high; secondly, when there are burrs on the edge of the strip, it is often easy to scratch, and the surface will be pierced with metal powder. Scratch the strip.
(2) Compressed Air Blowing
This method is the most common method for strip production. An air knife purge device is usually installed on the exit side of the rolling mill. The principle is to blow off the oil on the strip through compressed air. This method can still be used at low speeds. At high speeds, to blow off the oil sticking to the surface of the strip, it is necessary to increase the pressure and flow rate, resulting in larger oil mist secondary adhesion, and more importantly polluting the entire production. environment.
(3) The Non-Woven Mill Roll Degreasing
The roll is made of a non-woven fabric with internal porous structure and moisture absorption. It was first produced by 3M in the United States, commonly known as the “Millennium Roll”, but because of the high price and inconvenient maintenance, many manufacturers are daunted, and it is difficult for users to adopt them in large quantities. In China,we has developed a similar product-non-woven multi-purpose mill roll after years of hard work. Its performance is completely as beautiful as imported products, and the price is completely acceptable to users. It has been adopted by many users at home and abroad. Has obtained national utility model patents.
In addition to the above methods, there are currently a variety of degreasing methods such as oil removal by scraping sticks and oil removal by small rolls. There are even several methods for combining degreasing. There is a recognized simple and efficient degreasing method.
2 The Composition And Working Principle Of The New Oil Removal Unit
2.1 The Composition Of The Vacuum Oil Removal Unit
The vacuum degreasing unit is mainly composed of four parts, as shown in Figure 1.
2.2 Structure And Function Of Multi-Strand Wire Brush Roll
Made of nylon PP6, a nylon wire with a diameter of 1.20mm contains hundreds of fine fibers. When the strip is in pressure contact, it can form a flat friction surface, which will not scratch the surface, and will be effective at the same time Ground the oil and metal powder on the board surface, see Figure 2.
2.3 Vacuum Degreasing Principle Of Non-Woven Squeezing Roll
The squeezing of the traditional rubber roll is completely relying on the tight bond between the rubber body and the steel plate to hardly squeeze out the liquid. The non-woven squeezing roll makes full use of the non-woven fabric’s own porosity and moisture absorption. It can be seen from Figure 3 that the volume of the roll body shrinks and the density increases under a certain pressure. When the roll body rotates, the compressed part will rebound to form a vacuum state, and the liquid on the surface of the strip is sucked into the roll body. Under the pressure of the transmission power, the roll body is compressed again, and the air and liquid in the roll body are squeezed out, as shown in Figure 3.
Figure 3 Principle Diagram of Non-woven Squeezing Roll
Use the squeezing function of the non-woven mill roll to first squeeze most of the oil stains on the strip. After squeezing the oil with two non-woven mill rolls, the residual oil on the surface of the strip can be reduced to about 600 mg/m ’after measuring.
3 Research and development of aluminum strip vacuum squeezing machine
The vacuum squeezer is the latest product with invention patent developed by us.
The composition and working principle of the vacuum squeezer are as follows.
(1) Vacuum Squeezing Roll
The vacuum squeeze roll is in the hollow steel tube.
When the unit is working, the oil is squeezed into the hollow roll body. Whether the vacuum non-woven roll is easy to use depends on the following points: the density and size of the hole distribution on the hollow steel rod. The same is true with sparseness; the thickness and hardness of the non-woven fabric on the mill roll, the cloth is too thick and hard, it will not move, the cloth is too thin or too soft, it will affect the service life of the roll, and it is easy to fall off; non-woven fabric material Choose, non-woven fabric should have sufficient moisture absorption and abrasion resistance.
(2) Vacuum Workstation
According to factors such as the thickness of the strip and the speed of the rolling mill, a vacuum suction system is designed. The vacuum system is directly connected to the rotary joint of the vacuum roll, and the vacuum suction system provides extremely strong negative pressure to the vacuum roll, and the residual oil stuck on the surface of the roll is pumped into the roll cavity, and then enters from the rotary joint. filtering system.
(3) Filter Circulation System
In order to save fuel consumption, this filter system is specially designed. The oil drawn from the vacuum roll contains a lot of impurities. In order not to waste precious oil resources and save costs, the extracted residual oil is filtered out of impurities through this precise and efficient filtering system, so that the filtered rolling mill oil is led to the rolling mill oil tank for continuous recycling.
(4) Control System
The control of the vacuum squeezing unit is designed based on the principles of simplicity, practicality and convenient operation. The control adopts the most advanced PLC control, which can be directly connected to the panel of the main worktable of the rolling mill for direct control.
(5) Roll Change And Maintenance Mechanism
The structure of the unit is optimized, reasonable and convenient to maintain, especially the roll replacement is extremely convenient, saving a lot of valuable time for production and maintenance.
4 Application Effect Of Aluminum Strip Vacuum Degreasing Unit
At present, the vacuum degreasing unit is used in many ferrous metal manufacturers, and the effect is good, and the degreasing effect is much higher than that of various traditional methods, and it is unanimously praised by the manufacturers and industry experts. After on-site testing, when used on a finishing mill, the residual amount of oil is about 100mg/m.
The successful development of the vacuum squeezing unit is regarded by experts at home and abroad as a revolutionary achievement in the field of sheet metal. In recent years, the new type of vacuum degreasing unit has also been applied in the hot rolling production line of large aluminum plate and strip enterprises in China, and the application effect is very good. The comparison result between it and the traditional degreasing method is shown in Figure 4.
5 Summary
In the production of aluminum strip rolling, surface oil and liquid removal is an indispensable and important process. Because it has a significant impact on the surface quality, production efficiency and cost of the aluminum strip. At present, there is still a big gap with the advanced level of foreign countries. The new vacuum degreasing unit developed by Engineered Industries Limited has a series of excellent characteristics. It is a revolutionary achievement in the surface cleaning of plates and strips and is worthy of popularization and application.
