The Characteristics Of Horizontal Rolling Mill And Tandem Rolling Mill

The Characteristics Of Horizontal Rolling Mill And Tandem Rolling Mill

The horizontal rolling mill is mainly used for the production of various sections of steel, narrow hot strips, and small billets. The following are the main features of the horizontal rolling mill :

(1) A row of rolling mills is driven by a motor. The rolling speed of each rolling mill is the same, and the rolling speed cannot be increased as the length of the rolling stock increases, so the output is low and the labor productivity is low;

(2) The structure of the rolling mill is generally three-roller or two-roller alternate;

(3) The rolling mill operation mode is mostly shuttle rolling or loop rolling. With flexible deformation and strong adaptability, each rolling mill can roll several times. The product range is wide and the operation is relatively easy;

(4) The rolling mill equipment is simple, with less investment and quick construction.

The tandem rolling mills are arranged in a row according to the rolling direction of the rolling stock. The rolling stock is only rolled once on each rolling mill. Each rolling mill is driven separately. Each rolling mill has different rolling speeds, that is, the rolling speed of the rolling rolls can be related to the rolling stock. The reduction in the section or the increase in the length of the rolled piece increases. Therefore, compared with the horizontal rolling mill, the rolling mill has the advantages of short gap time, high production efficiency, and less auxiliary equipment.

However, when this kind of rolling mill works, the rolling stock sequentially enters each rolling mill without forming a continuous rolling relationship, and the rolling stock is lengthened as the number of rolling passes increases, and the distance between the racks increases as the length of the rolling stock increases, so Longitudinal mills occupy a longer plant. This type of rolling mill is only suitable for large and medium-sized steel production. In order to overcome this shortcoming, the tandem mill was further developed into an off-road and a chess mill.

In cross-country rolling mills and staggered rolling mills, the head and tail of the rolling stock are alternated in different passes, which means the upper head becomes the tail of the track, and the tail of this track becomes the next head again. The rolling stock has lateral movement during the rolling process. The arrangement of the cross-country rolling mills and staggered rolling mills is more concentrated, which overcomes the shortcomings of the long mill. These mills also have a fast rolling speed and are suitable for the production of large, medium, and small complex sections of steel such as I-beam, channel steel, and H-beam.

The Work Theory Of Film Bearing

The Work Theory Of Film Bearing

Film bearing is a radial running bearing that uses lubricant as a media, the basic working theory is, during the rolling process, the bearing journal moves because of the rolling power, and the bearing center and the bearing journal have skewing, making two zones in the gap of film bearing and journal, one is called amplification area, the gap is getting bigger and bigger according to the rotating direction, one is called constriction area, the gap is getting smaller according to the rotating direction. When the rotating journal brings the lubricant from the amplification area to the constriction area, the gap becomes smaller and smaller, forming a lubricant wedge, creating pressure on the lubricant oil pressure, the pressure from every point in the film altogether is bearing capacity of film bearing, when the rolling power is bigger than the bearing capacity, the journal center and the bearing center eccentric distance enlarges, in the constriction area, the gap between bearings changing fast in the direction of journal rotating, the thickness of film get to the thinnest, the pressure of film getting bigger, carry capacity getting bigger, until balance the rolling power of the journal will not deviation, the bearing and journal completely separated by the film, become all liquid lubricant in theory.

From the film bearing theory, we can sense that the most important specification is film thickness, if the thickness is too thin, and the impurity in the lubricant is too big, which is just like metal touching directly, can lead to burning inside, meanwhile, if the thickness of the film is too thin, if steel pushing accident happens, it is very easy to course direct contact which leads to burning, the smallest thickness of the film is related to bearing structure material, related parts’ accuracy, and film bearing system assemble accuracy, lubricant, and rolling power.

Types Of Furnaces---Induction Furnace (Two)

Types Of Furnaces---Induction Furnace (Two)

Induction Furnace:

Induction heating of metal will provide the heat required for the electrical furnace. An induction furnace will provide a clean, energy-efficient, and well-controlled process of melting when it is compared with other processes. Most of modern foundries use this type of furnace instead of cupolas to melt cast iron as the former emits lots of duct along with other pollutants. 

The capacity ranges from less than one kilogram to a hundred tonnes capacity is used in melting iron, steel, copper, aluminum, and other precious metals. As the process does not use combustion, the material temperature is not higher than the required to melt it. This process prevents the loss of valuable alloying elements. The induction furnace lacks the refining capacity where the charge materials clean the oxidation products and the known composition. The alloying elements may have a chance to lose alloying elements due to oxidation.

The frequency of operation is high and is dependent on the material that is to be melted, and the furnace capacity required. If the volume of the melts is small then it requires a higher frequency. A pre-heated furnace of the melting iron can melt the cold charge by tapping of the readiness within an hour. The power supply range is from 10 KW to 42 KW which melts in size ranges of 20 kg to 65 tonnes of the respective metals. The operating induction furnace can be used by the operators to identify the correct operation and its corresponding power level.

Types Of Furnaces --- Open Hearth Furnace（Three）

Types Of Furnaces --- Open Hearth Furnace（Three）

Open Hearth Furnace:

The open heart process is also called a Siemens-martin process i.e. steel making technique for most of the applications in the 20th century. This process seeks a means to increase the temperature in a metallurgical furnace that uses the waste heat given out from the furnace that directs the fumes from the furnace through a brick checker work. A brick is heated to a high temperature, and then it is introduced into the furnace. The device is first used to produce steel that is charged with pig iron and wrought iron along with their scrap. The US and Britain are best suited to the open hearth process.

Natural gas or atomized heavy oils are used as fuel. The air and fuel are heated before combustion. The furnace gets charged with blast furnace iron in liquid form, steel crap that is combined with ore, limestone, dolomite, and fluxes. The roofs and body of the furnace are made of highly refractory materials such as magnetic bricks. 600 tons is the capacity of the open hearth furnaces that are installed in groups for massive auxiliary equipment, that is needed to charge up the furnaces and to handle the liquid steel that can be employed efficiently. It is most commonly used in industrial applications such as electric arc furnaces and oxygen process-based furnaces.

Types Of Furnaces----Electric Arc Furnace（Four）

Types Of Furnaces----Electric Arc Furnace（Four）

Electric arc furnace

These furnaces are used to produce special quality steels that are lighter products as reinforcing concretes. Electric Arc Furnace does not use any hot metals as basic oxygen routes. The equipment is charged with a cold material that will generally be steel scrap. Other raw materials include the products from iron ore. Direct reduced irons, iron carbide, and pig iron (the iron product from a blast furnace) that is cast and is allowed to get cooled are the included products. This process will not be charged directly.

The steel scrap is induced into the furnace by an overhead crane. Then a lid is used that is swung into position over a furnace. An electric current is passed through the electrodes that are positioned in the lowered that lower furnace. Other metals also get added to the steel that provides the required chemical composition. Oxygen is blown to purify the steel and lime in addition to the combined impurities. After sample collection, the furnace is tilted to pour the floating slag on the molten steel. The modern furnace can melt up to 150 tonnes in around 90 minutes.

Types Of Steel

Types Of Steel

Strictly speaking, steel is just another type of iron alloy, and it's mainly including carbon steels, alloy steels, tool steels, and stainless steel four types.  

First, steel is still essentially (and overwhelmingly) made from iron. 

Second, there are literally thousands of different types of steel, many of them precisely designed by materials scientists to perform a particular job under very exacting conditions. 

When we talk about "steel", we usually mean "steels"; generally speaking, steels fall into four groups: carbon steels, alloy steels, tool steels, and stainless steels. These names can be confusing because all alloy steels contain carbon (as do all other steels), all carbon steels are also alloys, and both tool sheets of steel and stainless steels are alloys too. Now, we will explain the four different sheets of steel as following.

Carbon steels

The vast majority of steel produced each day (around 80–90 percent) is what we call carbon steel, though it contains only a tiny amount of carbon—sometimes much less than 1 percent. In other words, carbon steel is just basic, ordinary steel. Steels with about 1–2 percent carbon are called (not surprisingly) high-carbon steels and, like cast-iron, they tend to be hard and brittle; steels with less than 1 percent carbon are known as low-carbon steels and like wrought iron, are softer and easier to shape. A huge range of different everyday items is made carbon steels, from car bodies and warship hulls to steel cans and engine parts.

Alloy Steels

As well as iron and carbon, alloy steels contain one or more other elements, such as chromium, copper, manganese, nickel, silicon, or vanadium. In alloy steels, it's these extra elements that make the difference and provide some important additional feature or improved property compared to ordinary carbon steels. Alloy steels are generally stronger, harder, tougher, and more durable than carbon steels.

Tool steel

Tool steels are especially hard alloy steels used to make tools, dies, and machine parts. They're made from iron and carbon with added elements such as nickel, molybdenum, or tungsten to give extra hardness and resistance to wear. Tool steels are also toughened up by a process called tempering, in which steel is first heated to a high temperature, then cooled very quickly, then heated again to a lower temperature.

Stainless steels

The steel you probably see most often in stainless steel—used in household cutlery, scissors, and medical instruments. Stainless steels contain a high proportion of chromium and nickel, are very resistant to corrosion and other chemical reactions, and are easy to clean, polish, and sterilize.

Types Of Steel Rolling Mill Machine

There are many types of steel rolling mill machine that used to reduce the thickness of metal material or compress the material to create a uniform product such as the plate, wire rod, rebar, hot rolled coil, cold rolled coil and etc.

In addition, the steel rolling mills are divided into several types as follows:

Two-high rolling mills, which have a unique advantage in cost-saving cause the less expensive for manufacturing. And they are used for skin passing with small reductions of 1% to 2%.

Four -high rolling mills, which has a quick change roll system, can be equipped with roll bend and shape control and can be put in tandem, two to seven stands, instead of reversing mill.

Six-high rolling mills, which are similar to four-high rolling mills, also allows for substantial roll shape, depending upon the horizontal movement of the rolls. Furthermore, this kind of rolling mills is equipped with hydraulic screw downs, automatic shape control, and automatic gauge control.