It is said that there were rolling mills in Europe in the14th century, but it is recorded that in 1480, Italian Leonardo da Vinci designed a rough 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 universal rolling mill, 1853, the United States began to use three-high rolling mill, and the lifting platform was driven by steam engine to realize mechanization. Then Lauter Mill appeared in America. The first continuous rolling mill was built in 1859. Universal profile rolling mill appeared in1872; It was made into a semi-continuous strip mill at the beginning of the 20th century, consisting of two three-high roughing mills and five four-high finishing mills.
187 1 year, China started rolling iron plates with thickness less than 15mm and square and round bars with thickness of 6 ~ 120 mm in the iron drawing plant (rolling mill) affiliated to Fuzhou Shipping Bureau. 1890 hanyeping company hanyang iron works is equipped with two stands of 2450mm two-high medium plate mill driven by steam engine, three stands of 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 rolling mill is working base and transmission device.
Interpretation of technical terms
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. The working load of roller bearing is very heavy and varies greatly, so it is necessary.
rolling machine
Bearings should have low friction coefficient, sufficient strength and rigidity, and easy to replace rollers. Different types of roller bearings are selected for different rolling mills. Rolling bearings have high rigidity and low friction coefficient, but low bearing capacity and large overall size, and are mostly used as work rolls of strip mills. 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 arches.
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 "pressing device", has three types: manual, electric and hydraulic. Manual screwdown devices are mostly used in profile rolling mills and small rolling mills. The electric screw-down device comprises a motor, a reducer, a brake, a screw-down device, a nut screw-down device, a position indicator, a spherical pad and a pressure gauge; Low transmission efficiency, large moment of inertia of moving parts, slow response speed and low adjustment accuracy. 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. Its forms are: spring type, commonly used in profile rolling mill; Heavy hammer type, often used in blooming mills with large roll movement; Hydraulic type, often 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.
Manipulate handiwork
Cranes, transport vehicles, roller tables and transfer machinery.
ancillary equipment
There are power supply, power distribution, roller grinding, lubrication, water supply and drainage, oil supply, compressed air, hydraulic pressure, mill scale removal, machine repair, electrical repair, acid drainage, oil-water acid recovery and environmental protection.
Rolling mill terminology
Named according to rolling variety, rolling mill type and nominal size. For profile rolling mill, the principle of "nominal size" is named after the pitch diameter of herringbone gear on the gear seat; For the blooming mill, it is named after the nominal diameter of the roll; For strip mill, it is named after the length of work roll; For the steel pipe factory, it 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. 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 been improved day by day, 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 to meet new product quality requirements and improve economic benefits are being developed.