I want to do steel rolling in a steel factory. What is steel rolling used for? Be more specific.

Steel rolling is the process of using a rolling mill to pressurize steel billets to obtain the required shape specifications and properties. The rolling mill is mainly composed of several sets of rollers. The rollers are a pair of rollers with opposite rotation directions. A gap or hole of a certain shape is formed between the two rollers. The steel billet passes through the rollers and becomes a steel material of a certain shape.

Rolling above the recrystallization temperature is called hot rolling; rolling below the recrystallization temperature is called cold rolling.

Our common automobile sheets, bridge steel, boiler steel, pipeline steel, rebar, steel bars, electrical silicon steel, galvanized sheets, tin-plated sheets, including train wheels are all processed through the steel rolling process.

my country's large steel mills have used advanced continuous rolling mills since the 1970s. The continuous rolling mill has adopted a complete set of advanced automated control systems. The entire production process and operation monitoring are all controlled by computers. Simultaneous rolling on the frame rolling mill greatly improves production efficiency and quality.

my country’s crude steel production ranks first in the world. The annual crude steel output of the top ten domestic steel companies is more than 10 million tons. This year, steel restructuring has entered the fast lane, such as Guangdong Iron and Steel Group controlled by Baosteel, Shandong Iron and Steel Group mainly formed by Shandong Jigang and Laiwu Iron and Steel Group, and Hebei Iron and Steel Group. However, if my country's steel industry wants to revitalize, it must take a refined path. Hot-rolled coils and cold-rolled coils are still stuck in the bottleneck of focusing on output but not on quality. The steel rolling industry must take a high-end route. The prosperity of the shipbuilding, automobile manufacturing, and construction industries has brought opportunities to the steel rolling industry. However, the rise in ore prices has brought new difficulties to my country's steel rolling industry.

In order for the domestic steel rolling industry to truly become bigger and stronger, it is necessary to continuously strengthen the series of links such as billet quality, heating, roll shape control, coiling capacity, and pickling. In addition, those who make heavy machinery such as first-, second-, upper-, and too-heavy machinery must step up and explore high-precision steel rolling equipment. Domestic steel rolling research institutions such as Baosteel, Anshan Iron and Steel, Wuhan Iron and Steel, Shougang Design Institute, Dongda University, and Beijing University of Science and Technology must also strengthen joint development with steel groups.

China’s steel rolling industry still has a long way to go before it can be revitalized.

Rolling mill

A rolling mill is a device that implements the metal rolling process. It generally refers to the equipment that completes the entire process of rolled product production, including main equipment, auxiliary equipment, lifting and transportation equipment, and auxiliary equipment. But generally speaking, the rolling mill often refers only to the main equipment. It is said that rolling mills existed in Europe in the 14th century, but it is recorded that the Italian Leonardo da Vinci designed a sketch of a rolling mill in 1480. In 1553 the Frenchman Brulier rolled out gold and silver plates to make coins. Since then, rolling mills have appeared in Spain, Belgium and the United Kingdom. Figure 1 A rolling mill designed in 1728 for the production of round bars. A rolling mill designed in England in 1728 for the production of round bars. The United Kingdom had a serial small rolling mill in 1766. In the mid-19th century, the first reversible plate rolling mill was put into production in the United Kingdom and rolled out ship iron plates. In 1848, Germany invented the universal rolling mill. In 1853, the United States began to use a three-roller profile rolling mill (Figure 2, side view of the original three-roller rolling mill), and mechanized it with a lifting table driven by a steam engine. Then came the Lauter mill in the United States. In 1859 the first continuous rolling mill was built. The universal profile rolling mill appeared in 1872; at the beginning of the 20th century, a semi-continuous strip rolling mill was developed, consisting of two three-high roughing mills and five four-high finishing mills.

China began to use rolling mills in 1871 at the Iron Drawing Plant (steel rolling mill) affiliated to the Fuzhou Shipping Bureau; it rolled iron plates less than 15mm thick and square and round steel between 6 and 120mm. In 1890, the Hanyang Iron Works of Hanyeping Company was equipped with a steam engine-driven two-stand 2450mm two-high medium plate rolling mill, a steam engine-driven three-stand horizontal two-roll rail-beam rolling mill, and a 350/300mm small rolling mill. With the development of the metallurgical industry, there are now many types of rolling mills.

The main equipment of the rolling mill includes the working stand and transmission device (Figure 3 Schematic diagram of a two-roller reversible blooming mill).

The working machine base

is composed of rollers, roller bearings, racks, rail seats, roller adjustment devices, upper roller balancing devices and roll changing devices.

Roller

It is a component that plastically deforms metal (see roller).

Roll bearings

Support the roll and keep the roll in a fixed position in the frame. The working load of the roller bearing is heavy and changes greatly, so the bearing friction coefficient is required to be small, have sufficient strength and stiffness, and be easy to replace the roller. Different rolling mills use different types of roll bearings. Rolling bearings have high rigidity and small friction coefficient, but have small pressure-bearing capacity and large external dimensions. They are mostly used for work rolls of plate and strip mills. There are two types of sliding bearings: semi-dry friction and liquid friction. Semi-dry friction roller bearings are mainly bakelite, copper tile, and nylon tile bearings, which are relatively cheap and are mostly used in profile rolling mills and blanking machines. There are three types of liquid friction bearings: dynamic pressure, static pressure and static-dynamic pressure. The advantages are that the friction coefficient is relatively small, the pressure-bearing capacity is large, the operating speed is high, and the rigidity is good. The disadvantage is that the oil film thickness changes with speed. Liquid friction bearings are mostly used in back-up rollers of plate and strip mills and other high-speed rolling mills.

The rolling mill frame

consists of two "archways" to install the roll chock and roll adjustment device. It must have sufficient strength and steel to withstand the rolling force. There are two main types of racks: closed and open. The closed frame is an integral frame with high strength and rigidity. It is mainly used for blooming mills and plate and strip mills with large rolling forces. The open frame consists of two parts: the frame body and the upper cover, which facilitates roll change. It is mainly used in horizontal profile rolling mills.

In addition, there are also mills without arches.

Rolling mill rail seat

It is used to install the machine frame and is fixed on the foundation, also known as the foot plate. It can withstand the gravity and tilting moment of the work base while ensuring the accuracy of the installation dimensions of the work base.

Roll adjustment device

It is used to adjust the roll gap so that the rolled piece reaches the required cross-sectional size. The upper roller adjustment device is also called the "press-down device" and has three types: manual, electric and hydraulic. Manual pressing devices are mostly used in profile rolling mills and small rolling mills. The electric press-down device includes components such as a motor, a reducer, a brake, a press-down screw, a press-down nut, a press-down position indicator, a spherical pad and a pressure gauge; its transmission efficiency is low, the rotational inertia of the moving part is large, and the reaction The speed is slow and the adjustment accuracy is low. Since the 1970s, after the plate and strip rolling mill adopted the AGC (automatic thickness control) system, hydraulic reduction devices have been used in new strip cold and hot rolling mills and thick plate rolling mills, which have the advantages of small plate thickness deviation and high product qualification rate. .

Upper roll balancing device

A device used to lift the upper roll and prevent the rolling stock from being impacted when entering and exiting the roll. The forms are: spring type, mostly used in profile rolling mills; hammer type, often used in blooming mills with large roll movement; hydraulic type, mostly used in four-high plate and strip mills.

In order to improve the operation rate, the rolling mill is required to change rolls quickly and conveniently. There are four roller changing methods: C-shaped hook type, sleeve type, trolley type and whole frame roller changing type. The first two methods are used to change the rolls with the assistance of a crane, while two sets of frames are required for roll change in the entire frame. This method is mostly used in small rolling mills. Cart roll changing is suitable for large rolling mills and is conducive to automation. At present, rolling mills adopt fast automatic roll changing devices, and it only takes 5 to 8 minutes to change a roll.

The transmission device

consists of a motor, a reducer, a gear seat and a connecting shaft. The gear seat distributes the transmission torque to two or several rollers.

Auxiliary equipment includes equipment for a series of auxiliary processes in the rolling process. Such as raw material preparation, heating, steel turning, shearing, straightening, cooling, flaw detection, heat treatment, pickling and other equipment.

Lifting and transportation equipment: cranes, transport trucks, rollers and transfer machines, etc.

Ancillary equipment includes power supply, power distribution, roll grinding, lubrication, water supply, drainage, fuel supply, compressed air, hydraulic pressure, iron oxide scale removal, machine repair, electrical repair, acid discharge, oil, water, acid recycling, and environmental protection equipment.

Naming of rolling mills

Named according to rolling varieties, rolling mill types and nominal dimensions. The principle of "nominal size" for profile rolling mills is named after the pitch circle diameter of the gear seat; the roughing mill is named after the nominal diameter of the roll; the plate and strip mill is named after the length of the work roll body; the steel pipe rolling mill is named after the maximum production capacity Named according to pipe diameter. Sometimes it is also named after the inventor of the rolling mill (such as Sendzimir Mill).

Selection of rolling mill

Select the type and size of the finished product or semi-finished product rolling mill according to the product variety, specifications, quality and output requirements, and equip it with necessary assistance and lifting Transportation and ancillary equipment are then selected based on a balance of various factors.

Rolling mill power facilities

In 1590, Britain began to use water turbines to drag rolls. Until 1790, water turbines equipped with stone flywheels were used to drag four-roller steel plate rolling mills (Figure 4 Water turbine Dragging steel plate mill). In 1798 England began to use steam engines to drag rolling mills. Modern rolling mills are driven by DC or AC motors, either individually or in groups through gears.

Classification of rolling mills

Rolling mills can be classified according to the arrangement and number of rolls, the arrangement of the stands, and the products produced, which are listed in Table 1. Rolling mills Classification according to the arrangement and number of rolls, Table 2: Classification of rolling mills according to the arrangement of the stands, and Table 3: Classification of rolling mills according to the products produced.

Development of rolling mills

The development trend of modern rolling mills is continuity, automation, specialization, high product quality and low consumption. Since the 1960s, great progress has been made in the design, research and manufacturing of rolling mills, which has improved the performance of hot and cold strip rolling mills, thick plate rolling mills, high-speed wire rod mills, H-section rolling mills and continuous pipe rolling mills, and the emergence of rolling mills. It has a series of advanced equipment such as a wire rod rolling mill with a rolling speed of up to 115 meters per second, a fully continuous strip cold rolling mill, a 5500 mm wide and thick plate rolling mill and a continuous H-beam rolling mill. The unit weight of raw materials used in rolling mills has increased, hydraulic AGC, flatness control, electronic calculator process control and testing methods have become more and more perfect, and rolling varieties have continued to expand. Some new rolling methods suitable for continuous casting and rolling, controlled rolling, as well as rolling mills with various special structures to adapt to new product quality requirements and improve economic benefits are under development. (See the color picture of the production scene of the continuous rolling unit of the Anshan Iron and Steel Company's blooming mill, the fixed-length cutting equipment of the blooming billet - 2000-ton shear, the slab blooming mill rolling the slab, and the blooming workshop of Shanghai No. 5 Iron and Steel Plant. Hot furnace tapping, 4200 mm thick plate rolling mill made in China, hot straightening machine for wide and thick steel plates, high pressure water descaling machine before steel plate roughing mill, 2300 mm steel plate rolling mill production scene, 1700 mm strip hot rolling mill main control Room, strip cold rolling mill is producing, finished products produced by strip cold rolling mill - steel coils, strip hot dip galvanizing unit, H-shaped wide edge I-beam rolling mill, medium-sized steel rolling mill, profile cutting to length The main methods are hot sawing, rail cooling beds in large rolling mills, wire coil cooling to ensure wire rod performance, new 45° twist-free finishing mills for rolling wire rods, and enclosures for small rolling mills.

Important auxiliary equipment of the horizontal small rolling mill, the finished product collection equipment of the wire rod rolling mill - wire rod coiler, automatic pipe rolling machine for rolling seamless steel pipes with a diameter of 140 mm, large diameter steel pipes made in the 1970s, with a diameter of 2540 mm, modern One of the pipe production methods - large-diameter spiral welded pipes, a leveling machine to ensure the dimensional accuracy of steel pipes in a seamless steel pipe factory, a seamless steel pipe blank being pierced, a Sendzimir 20-roll mill for rolling foil, a train wheel and hoop rolling mill working scene, large-scale forging equipment made in China - 32,000-ton hydraulic press, new plastic processing equipment - precision forging machine, 3,000-ton horizontal extrusion press, aluminum foil rolling mill, and a wide range of rollers for rolling various products, Aluminum continuous casting and rolling mill)