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Rail basics

Time:2022-09-16 Click:298

Introduction to the historical changes of railway rail, knowledge of modern rail, rail classification, rail production and transportation and other basic knowledge.

Steel rail can be said to be a very common and insignificant thing in our life, can be seen everywhere in movies and TV dramas. It always sits in the middle of nowhere, crushed by trains, guided by trains, buried in dirt, deep in dust. But it's not just the foundation of a train, it's also a guy with a history. Today we will talk about it, take the reader to understand the knowledge of rail.


The history of steel rail must begin in Britain. After all, the world's first railway was born in Britain. Britain was the "empire on which the sun never sets" and built railways all over the world, including China.


Steel rails did not start out as they are now, or even as they are now made. They began as a square piece of wood, and later were covered with iron sheets. As the speed and weight of the train increased, so did the rail, and it will continue to change.


After entering the 20th century, the shape of the rail basically became no big difference with the present, are "work" shape, this graphic is also because of the original Ministry of Railways LOGO(one worker made up of a locomotive) and popular. In modern times, with the deepening of research, train speed and axle load increase gradually, the requirements for smoothness are higher and higher, the level of production and manufacturing technology is also gradually improved, and the classification of rail is more and more fine.


Sort by weight. The type of rail is usually according to the weight of the distinction, for example, we often say that 50 rail, refers to the weight of 50kg/m rail, and so on, there are 38 rail, 43 rail, 50 rail, 60 rail, 75 rail, of course, there are 24 rail, 18 rail, but that is ancient times. The 43 rails and above are generally called heavy rails.


Classified according to manufacturing process. According to the classification of manufacturing process, the rail can be mainly divided into hot rolled rail and heat treatment rail. In fact, the rail is produced by hot rolling process, heat treatment rail is in hot rolling molding rail for heat treatment again, divided into online heat treatment and offline heat treatment of two, online heat treatment has been the mainstream, more energy saving and more efficient.


Categorize by strength. Rail is a complex and alloy, in addition to the main composition of iron (Fe), there are five elements, carbon (C), manganese (Mn), silicon (Si), phosphorus (P), sulfur (S), of course, there will be some decisive role of trace elements vanadium (V), chromium (Cr), as well as some rare earth elements. The three most important factors to consider the performance of a rail are strength, hardness and toughness (generally measured by elongation after breaking), which are interrelated. The most important of these is strength, so there is also a way to classify the rails according to their strength grade. We see 780Mp, 880Mp, as high as 1450Mp and so on, according to different needs to choose. Generally speaking, the strength of the subway rail is between 880 and 1180Mp.


As an aside, generally speaking, the most convenient way to improve strength, hardness and toughness is not to change the element formula, but to carry out heat treatment, the effect is obvious, who knows who uses. The following image is taken from TB/T 2344-2012.


Categorize by use. Classification by purpose is basically the most common practice, now all kinds of rail transit construction is in the ascends, the uses of steel rails are varied. Let's start with the national railroad. The first is high-speed rail, which basically uses 60 rail for the track inside the station (50 rail for part of the parking line) and 60 rail for the main line (including the station line and auxiliary line). However, the rail of high-speed rail has high requirements for flatness and size of each part.


There are also regular rail basic depot and parking lot is 50 rail, the main line is 60 rail. And then there are special railways. First, heavy-haul railway, similar to Daqin, Shuohuang Railway and Shenhua coal line, is characterized by large axle load of the train total weight is also large, a train can reach more than 10,000 tons of load, this kind of railway is generally used by special manufacturing 75 rail, can greatly increase the service life. The second is the alpine railway, specifically the Qingzang Line, through the permafrost, the steel rail cold resistance, corrosion resistance requirements are very high, the use of special manufacturing 60 rail.


Then there is the current hot market for subways. At present, the subway in China basically uses 50 rail in the car depot and 60 rail in the main line. Of course, the main line of the old subway uses 50 rail. There is also the tram that many small cities currently choose. Trams are prone to derailment due to their small wheels, small turning radius and small turnout numbers, so they choose trough steel rails with their own guard rails.


The rest of the other railways, do not belong to the general railway, do not belong to the local government, but belong to the enterprise, so the standard is not unified, the gauge is not standard, the rail type is not fixed, 38 rail, 43 rail, 50 rail will be used, such as many large enterprises, steel mills, shipyards and so on. Having said that, reprint a picture and put the rail types mentioned above together to illustrate. (If you can't see clearly, click open to see)


Rail manufacturing is the foundation of rail transit industry. No matter how beautiful the picture is, it is useless if it cannot be made. However, rail manufacturing is not high-tech and there are many places where it can be done. Now China produces the best quality rail in the world and can compete with Nippon Steel in Australia, Brazil and the United States.


In the country, mainly Panzhihua Steel, Baotou steel, Angang steel, Wuhan steel production. Panzhihua Steel and Baotou Steel are now the main force, Angang is a time-honored brand, and Wuhan Steel is also a long history in recent years has also been rebuilt and is developing strength.


How can long rails be transported when they are produced? There are usually two ways to do this. Long rail transport vehicle is a special transport vehicle manufactured for long rail railway transport. Since its production, there have been T11, T11A, T11B, T11BK and other products. T11 was first put into use by Beijing Railway Bureau in 1988, and became T11A after improved design. On the basis of T11A, the T11B is a partial improvement of the design of the crew and the addition of one working car. T11BK is on the basis of the previous generations of models, in the body structure, on-board facilities and other aspects of comprehensive improvement, the use of K2 bogie and other technologies.


With the large-scale construction of high-speed railway and passenger dedicated line, China has developed the long-rail common flat car connected transportation technology. A series of loading reinforcement schemes of 50m, 100m and 500m long rail common flat car have been formulated.


Common flat car connected transport can effectively utilize vehicle resources, and after the completion of railway passenger dedicated line construction, the common flat car can still be restored, which solves the problem that the special vehicle is difficult to reuse. It has avoided the waste of transportation capacity and made important contributions to the construction of high-speed railway and passenger dedicated lines.


The US and other countries have studied China's high-speed rail and know the impact of Chinese rail on the overall high-speed rail technology. Today, China has the world's largest high-speed railway network, and the highest operating speed, won the recognition of the world, the once introduced foreign technology far beyond.


In the past, we relied on foreigners to build railways for us. In the future, we will also build more for them.