I want to do steel rolling in a steel mill. What is rolling steel for? Be specific.

Rolling is the process of pressing billet into the required shape, specifications and properties with a rolling mill. The rolling mill is mainly composed of several groups of rollers. Rollers are a pair of rollers with opposite rotating directions, and a seam or hole with a certain shape is formed between the two rollers, and the billet is transformed into a steel product with a certain shape through the rollers.

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

Our common automobile plate, bridge steel, boiler steel, pipeline steel, rebar, steel bar, electrical silicon steel, galvanized sheet, tinplate including train wheels are all processed by rolling technology.

China's large steel mills began to use advanced continuous rolling mills in the 1970s, and the continuous rolling mills adopted an advanced automatic control system. The whole production process and operation monitoring are controlled by computer, and the rolled piece is rolled on several rolling mills at the same time, which greatly improves the production efficiency and quality.

China ranks first in the world in crude steel production. The annual output of crude steel in the top ten domestic iron and steel enterprises is above100000 tons. This year, iron and steel restructuring 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 Laigang, and Hebei Iron and Steel Group. However, to revitalize China's iron and steel industry, we must take the road of refinement. At present, hot-rolled coils and cold-rolled coils are still stuck in the bottleneck of heavy output and light quality. The steel rolling industry must take the high-end route. The prosperity of shipbuilding, automobile manufacturing and construction industry has brought opportunities to the steel rolling industry, but the rise of ore prices has brought new difficulties to the steel rolling industry in China.

In order to make the domestic steel rolling industry really bigger and stronger, it is necessary to continuously strengthen the billet quality, heating, roll shape control, coiling capacity, pickling and other links. In addition, in order to be heavy, heavy, heavy and overweight heavy machinery, we must rise up and explore high-precision steel rolling equipment. Domestic steel rolling research institutions such as Baosteel, Angang, WISCO, Shougang Design Institute, Dongda University and Beijing University of Science and Technology should also strengthen joint development with iron and steel groups.

There is still a long way to go to revitalize the steel rolling industry in China.

rolling machine

Rolling mill is the equipment to realize the metal rolling process. Generally, it refers to the equipment that completes the whole process of rolled material production, including main equipment, auxiliary equipment, lifting and transportation equipment and auxiliary equipment. Generally speaking, however, the rolling mill usually refers only to the main equipment. It is said that there were rolling mills in Europe in14th century, but it is recorded that 1480 Italian Leonardo da Vinci designed the sketch of the rolling mill. 1553 French Bruriel rolled out gold and silver plates to make coins. Since then, rolling mills have appeared in Spain, Belgium and Britain. Figure 1 1728 The rolling mill designed for producing round steel is 1728 the rolling mill designed for producing round steel in Britain. 1766, there was a small serial rolling mill in Britain. /kloc-in the middle of the 0/9th century, the first reversible plate mill in Britain was put into operation, and the marine iron plate was rolled out. 1848 Germany invented the universal rolling mill, 1853 America began to use the three-high rolling mill (the original three-high rolling mill in fig. 2 is viewed from the side), and the lifting table driven by the steam engine was used to realize mechanization. Then Lauter Mill appeared in America. The first continuous rolling mill was built in 1859. Universal profile rolling mill appeared in1872; At the beginning of the 20th century, a semi-continuous strip mill was manufactured, consisting of two three-high roughing mills and five four-high finishing mills.

In 187 1, China began to use rolling mills in the iron drawing plant (rolling mill) under Fuzhou Shipping Bureau. For rolling iron plates with thickness less than 15mm and square steel and round steel with thickness of 6 ~ 120 mm 1890, Hanyang Iron Works of Hanyeping Company is equipped with two-stand 2450mm two-high medium plate mill driven by steam engine, three-stand two-high rail beam mill driven by steam engine and 350/300mm small mill. With the development of metallurgical industry, there are more and more kinds of rolling mills. The main equipment of the rolling mill is the working base and transmission device (Figure 3 is the schematic diagram of the two-high reversible blooming mill).

Work base

It consists of a roller, a roller bearing, a frame, a rail seat, a roller adjusting device, an upper roller balancing device and a roller changing device.

roll

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

roller bearing

Support the roller and keep it in a fixed position in the frame. Roller bearings have heavy working load and great changes, which require small friction coefficient, sufficient strength and stiffness, and convenient replacement of rollers. Different types of roller bearings are selected for different rolling mills. Rolling bearing has high rigidity and low friction coefficient, but it has small bearing capacity and large overall size, and is mostly used as the work roll of strip mill. There are two kinds 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 cogging machines. There are three kinds of liquid friction bearings: dynamic pressure, static pressure and dynamic and static pressure. The advantages are relatively small friction coefficient, large bearing capacity, high working speed and good rigidity, while the disadvantage is that the oil film thickness changes with the speed. Liquid friction bearings are mainly used as backup rolls for strip mills and other high-speed mills.

mill housing

It is composed of two "arches" for installing the roller bearing seat and roller adjusting device, and it needs enough strength and rigidity to bear the rolling force. There are two main types of racks: closed and open. Closed stand is a kind of integral stand with high strength and rigidity, which is mainly used for blooming mill and strip mill with high rolling force. The open frame consists of a frame body and an upper cover, which is convenient for changing rolls and is mainly used for horizontal profile rolling mills.

In addition, there are rolling mills without archways.

Rolling mill rail seat

Used to install the frame and fix it on the foundation, also called the baseboard. Bear the gravity and tilting moment of the working base to ensure the accuracy of the installation size of the working base.

Roller adjusting device

Used to adjust the roll gap to make the rolled piece reach the required section size. Upper roller adjusting device, also known as "screw-down device", has three types: manual, electric and hydraulic. Manual screwdown devices are mostly used in profile rolling mills and small rolling mills. The electric press-down device comprises 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 moment of inertia of moving parts is large, the reaction speed is slow and the adjustment accuracy is low. Since the 1970s, AGC (Automatic Thickness Control) system has been adopted in strip mills, and hydraulic screwdown devices have been adopted in new cold-rolled strip mills and heavy plate mills, which have the advantages of small plate thickness deviation and high product qualification rate.

Upper roller balancing device

A device for lifting the upper roll and preventing the rolled piece from being impacted when entering or leaving the roll. Forms are: spring type, mostly used for profile rolling mill; Heavy hammer type, often used in blooming mills with large roll movement; Hydraulic type, mostly used in four-high strip mill.

In order to improve the operation rate, it is required that the roll change of rolling mill is fast and convenient. There are four roll changing methods: C hook type, sleeve type, trolley type and whole frame roll changing type. The first two methods are crane-assisted roll change, while the whole roll change requires two sets of racks. This method is mostly used in small rolling mills. Car roll changing is suitable for large rolling mills and is beneficial to automation. At present, the rolling mill adopts a fast automatic roll changing device, and it only takes 5 ~ 8 minutes to change the roll once.

gearing

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

Auxiliary equipment includes 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 vehicles, roller tables and conveyors, etc.

Auxiliary equipment includes power supply, power distribution, roller grinding, lubrication, water supply and drainage, oil supply, compressed air, hydraulic pressure, mill scale removal, mechanical maintenance, electrical maintenance, acid drainage, oil, water and acid recovery, and environmental protection.

Rolling mill terminology

Named according to rolling variety, rolling mill type and nominal size. The principle of "nominal size" is named after the pitch circle diameter of herringbone gear on the gear seat of profile rolling mill; The blooming mill is named after the nominal diameter of the roll; The strip mill is named after the length of the work roll body; The steel pipe factory is named after the largest pipe diameter produced. Sometimes named after the inventor of the rolling mill (such as the Sendzimir mill).

Selection of rolling mill

According to the requirements of product variety, specification, quality and output, select the type and size of finished or semi-finished rolling mill, and equip it with necessary auxiliary, lifting, transportation and auxiliary equipment, and then make a balanced selection according to the requirements of various factors.

Power facilities of rolling mill

1590, Britain began to use water turbines to drive road rollers. Until 1790, there were still four-high steel plate mills driven by water turbines with stone flywheels (Figure 4: steel plate mills driven by water turbines). 1798, Britain began to use steam engines to drive rolling mills. Modern rolling mills are all driven by DC or AC motors, either by a single machine or by a group of gears.

Classification of rolling mills

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

Development of rolling mill

The development trend of modern rolling mill is continuity, automation and specialization, with high product quality and low consumption. Since the 1960s, great progress has been made in the design, research and manufacture of rolling mills, which have improved the performance of strip cold and hot rolling mills, thick plate rolling mills, high-speed wire rod rolling mills, H-beam rolling mills and continuous pipe rolling mills, and a series of advanced equipment such as wire rod rolling mills, fully continuous strip cold rolling mills, 5500mm wide and thick plate rolling mills and continuous H-beam rolling mills have emerged. The single weight of raw materials used in the rolling mill has increased, the hydraulic AGC, shape control, electronic calculator process control and detection means have become increasingly perfect, and the rolling varieties have been continuously expanded. Some new rolling methods, such as continuous casting and controlled rolling, and rolling mills with special structures, are being developed to meet new product quality requirements and improve economic benefits. (See the production site of continuous rolling mill in Angang Initial Rolling Plant, 2000-ton shearing machine for initial rolling billet, tapping production site of soaking pit in initial rolling workshop of Shanghai No.5 Iron and Steel Plant, domestic 4200mm thick plate mill, hot leveler for wide and heavy plate, high-pressure draft gauge before rough rolling and 2300mm steel plate mill. /kloc-main control room of 0/700 mm hot strip mill, finished products produced by cold strip mill-hot dip galvanizing line for steel coil and strip, H-type wide-edge I-beam mill, medium-sized mill, main method of cutting profile to length-hot saw, rail cooling bed of large mill, coil cooling to ensure wire performance, new 45 twist-free finishing mill for rolling wire rod, important auxiliary equipment of small horizontal mill and finished product collection equipment of wire rod mill- Automatic pipe mill for rolling seamless steel pipes with a diameter of 140mm, large-diameter steel pipes with a diameter of 2,540mm manufactured in 1970s, large-diameter spiral welded pipes, one of modern pipe-making methods, homogenizer of seamless steel pipe factory to ensure the dimensional accuracy of steel pipes, Sendzimir 20-roll seamless steel pipe blank piercing mill, aluminum foil rolling mill, domestic large-scale forging equipment-32,000t hydraulic press, new type.