Roller: description, production technology and plants

Metallurgy is one of the main branches of modern production. It is thanks to it that huge financial receipts go to the state budget, as steel and pig-iron products, as a rule, are exported and form the currency proceeds of the combine itself or the plant and the country. There are various metallurgical enterprises, the working cycle of which can be either complete or incomplete. But in any case, the final stage of the metallurgical cycle will be the rolling of metal in order to obtain the profile required for the consumer. It is in the rolling shops that beams, channel bars, rails, and so on are produced. The main elements of any rolling mill are rolling rolls. Plants of the metallurgical complex without them are simply unthinkable, so we'll talk in detail about the rolls in this article.

general description

Rolled metal is a rather complicated operation, energy-consuming and requires special skills and knowledge from the personnel. The compression of the material produced by the rolling roll allows to achieve certain dimensions of the profile being processed. It is important to know that rolls in the course of their work take on an impressive effort, which occurs directly during the work of the entire rolling line. That is why the rolling roll is the most wearing part of any rolling mill.

Components and characteristics

All rolls have three main components, including:

• A barrel of felling. It is she who is in direct contact with the molten and processed metal. The barrel has two main linear parameters - length (L) and diameter (ØD).
• Cervical (supporting parts) - located on the sides of the barrel and supported by the roll bearings. Also characterized by length and diameter.
• Drive end.

For a rotary-sorting mill, the main parameters are: nominal diameter, diameter of the collars and working diameter. In those cases where the rolling roll serves to rotate with a universal type spindle, its drive end will have the shape of a blade or cylinder. The drive end will have the form of the spider if the roll is rotated by means of a club (there must be an intermediate clutch).

Rolls for sheet metal

Sheet rolling rolls, the manufacture of which - a fairly laborious process, perform the rolling of tape, stripes. The barrel of such rolls is smooth, made in cylindrical form.

Rolled rolls are used for the production of shaped material, which can have both round and square sections (I-beams, corners).

The barrels of the rolling rolls are made slightly convex if they are intended for cold rolling of sheet metal. In all other cases, the roll barrel is given a concave shape for hot rolling. This is done because at the moment the metal moves along the roll of the barrel it will be heated and straightened.

Rolls for long products

The barrel of such rolls has special depressions (streams) that repeat the profile of subsequently rolled metal. Brooks of a pair of rolls, when connected together, form a caliber. The length of the barrel of the sorting rolls depends on the width of the rolled workpiece and the calibration conditions.

Sortovye rolls are characterized by the nominal diameter and barrel length. If the mill has many stands and different diameter rolls, then the diameter of the finishing rolls will be dominant.

For the purpose of the sorting rolls are divided as follows:

• For heavy crimping mills.
• For coarse-grained and rail-mill mills.
• For medium-medium rolled products.
• For fine-rolled steel.
• For wire mills.
• For stripe mills.

Centrifugal casting

Modern production of rolling rolls as one of the main methods provides a method of centrifugal casting. This method is very expensive, but it fully allows to maximally compact the structure of the metal of the outer surface, which is the work of the roll. This approach allows a significant increase in the service life of the product.

For this method, a special machine having a horizontal axis of rotation of the centrifugal casting mold is used. The mold itself is mounted on support rollers. The drive rollers are mounted in such a way that the synchronization of the rotation process is fully ensured. Located at the top of the safety roller has a gap in relation to the rim of the riding of the form itself. To absorb vibration between the rollers and the hub, there are damping gaskets. Reducing the level of vibration and vibration of the form reduces to zero the probability of getting a marriage.

Rolling of rolls by a centrifugal method is carried out from high-alloyed cast iron. In the rotating around its vertical axis the mold is filled with metal, the volume of which is within 95% of the total volume of the working layer of the rolling roll.

The indisputable advantages of centrifugal casting are:

• Providing high roll density.
• Increasing the wear resistance of the roll.
• Absence of shells, voids, nonmetallic inclusions, slag.

Forging method

This is the most expensive method of producing rolling rolls, which nevertheless makes it possible to maximally harden the entire body of the roll. Thanks to this, reliability and durability significantly increase.

The very same forging is performed on special automated complexes, designed and manufactured using advanced technologies. The power of these units can be up to 150 MN.

Obtained in this way rolls are most often used on blooming and slabbing, as well as varietal mills. These steel rolls have an increased coefficient of friction at the moment of contact with the rolled workpiece. Such a nuance is extremely important for crates with a high degree of reduction.

By itself, forging provides the following operations:

• Billetting of the ingot.
• Precipitation.
• Stretching.
• Forging on the size of the forgings.

Processing of rolling rolls after forging provides for a complex thermal treatment, the final stage of which is, of course, surface hardening and tempering.

Titanium production

Today, Russia is one of the countries that regulate the world market for steel and alloys. Therefore, the creation of components and parts for metallurgy in the country paid the most attention. In particular, the Magnitogorsk Rolling Mill Plant is one of the leaders in the production of these products.

In July 2016 new high-capacity crucible induction furnaces were launched at this enterprise . These high-tech units will produce complex alloys, reduce the amount of consumed ferroalloys and charge. At the same time, the reduction of electricity consumption will be about 10%. The melting mode can be performed at a frequency of 250 Hz, and the debugging and mixing at a frequency of 125 Hz. Equally important is compliance with environmental requirements: the reduction of harmful emissions in these furnaces will occur 2.6 times.

In general, the Ural enterprise regularly supplies the market for rolling rolls with its products and is an actively developing company.

The Sverdlovsk Giant

You can not ignore the Kushvinsky plant of rolling rolls. Its products are all kinds of rolls, bandages for them. At the enterprise rolls of rolling mills are made with the use of such materials for the working layer, as:

• Indefinite.
• Indefinite, improved by special carbides.
• High-chromium cast iron.
• High-chromium steel.
• High speed steel.

The neck and core of sheet rolling rolls are produced from extra strong cast iron.

Rolls for bars are produced on the basis of bainitic and pearlite alloyed cast iron with a spherical or lamellar form of graphite.

Ukrainian producers

In Ukraine, there are three main enterprises for the production of rolling rolls: Dnepropetrovsk, Lutuginsky and Novokramatorsky rolling mill plants.

The Dnieper combine has the widest range of roll production, not only for metallurgy, but also for other industries. Very often the enterprise works for a specific customer, connecting its highly qualified specialists from the technical department to create various drawings and new models of rolls.

Prior to the start of hostilities in the Donbass in 2014, Lutuginsky rolling mill plant was also among the best in the cohort of the best. Its products were supplied not only to all metallurgical enterprises of Ukraine, but also to many countries of the near abroad and Europe. However, the military conflict led to the fact that the plant was stopped. The fixed assets of the enterprise also suffered. But still in 2015 it was possible to restart the enterprise, and nowadays it started receiving orders from the Russian Federation.

Quality control of rolls

In the production process, absolutely every rolling roll must pass the procedure of technical quality control of its manufacture. Particular attention is given to:

• To the chemical composition of the starting material.
• Analysis of the structure of the material of the product (roll).
• Analysis of centricity and geometric dimensions.
• Control the degree of hardness of the working layer of the roll.
• Control the degree of roughness of the working surface.
• Analysis of the structure of the metal of the surface layer.

Packaging

All rolling rolls (factories that produce them, have the appropriate quality certificates) are delivered to the customer in a special package. This container is often a wooden box with partitions, inside of which rolls are laid and securely fastened by tightening elements. Packaging container manufacturers also pay close attention, because the poor fastening of the rolls and the lack of proper protection of the working and landing surfaces of the industrial product may well lead to negative consequences in the quality of the rolls.

Conclusion

Rolling swaths, the production technology of which has been discussed in detail above, have a significant effect on the products obtained as a result with their help. Therefore, the world's leading producers of rolled products pay special attention to this element. Each head of a metallurgical enterprise understands perfectly well that the final profitability of the entire production will largely depend on the technical condition of the rolling mill as a whole and the rolling rolls in particular.