Domestic "double high" wire make China high-speed rail "power full"
As technology continues to improve, today my country’s copper-chrome zirconium wires can achieve 83% of conductivity, while intensity reaches 620 MPa. my country’s high-strength high-director contact network wire with independent intellectual property rights can provide strong technical support for the construction of new high-speed rails.
◎ This newspaper reporter Chen Yu
350 kilometers per hour, 36,000 km from the operating mileage, 30 provinces and districts outside Tibet … China high-speed rail is refreshed with the "high-speed rail" and records of my country in China. As the "heart" of the high-speed train, the power supply system is the key to secure, high speed, reliable, and stable operation of the train.
"High-speed railway high-strength high-director contact network wire" "high-speed railway high-strength high-promoting contact network wire", the key technology and application of high-speed railway, high-speed high-director contact network wire, China, China Iron Electrification Design, Research Institute, Tianjin, realized the complete country of my country’s high-speed rail contact network wire. After 10 years, the "hanging net" operation on the high-speed rail line of 1.30,000 kilometers such as Beijing, Beijing, Beijing, Beijing, and Chengxi, confirmed that its performance leads the "world high-speed rail". The project also won the second prize of the 2020 National Science and Technology Progress Award, and the project was authorized to authorize 32 patents, 31 SCI papers, and 6 national standards and 2 industry standards.
Copper magnesium wire has reached the safety limit
As the saying goes, the train runs fast, close to the headband. So where is the traction power of the "front"?
"When people wait in the high-speed rail station, they often see the transmission lines along the railway along the railway. These power transmission lines are high-speed railway contact networks. The electricity required for high-speed train operation is to transport through the contact network on the upper end of the locomotive." Wang Litian Introduction, Once the contact network is powered down or the trachee is poor contact with the contact network, the supply of the train will affect the supply of the train.
At the same time, the three major core technical bottlenecks that restrict high-speed train speed increase is also the traffic flow of the bow. In order to ensure the stability of the train under high-speed driving, the contact network wire must have large tension and large carrier capacity, which requires the wires to have high strength and high conductivity, but also to ensure that the contact network is lightweight, and cannot give the project. Increase investment.
Wang Li Tian explained: "When the train speed is 300 km / h, it is from more than 90% of the resistance from wind resistance, and the square of wind resistance and speed is proportional to the speed of the train. Positive ratio. After the power becomes large, the current is also increased accordingly. Therefore, the contact network wire is required to have high conductivity. "
"When ensuring high conductivity, the contact network wire also needs to guarantee high strength." Wang Li Tian said that the train cannot be detached between the trains and the wires, and must be closely contacted. Only the fluctuation speed of the wire is greater than 1.4 times that of the train speed, in order to ensure that the electrical arch and the contact network wire do not detach. The speed of the flossing wire must increase the tension of the wire. In the case of the weight of the wire, it is necessary to increase the wire strength, so that the wire strength reaches 2.0 or more. That is, the maximum pull-off force that the wire can be affected needs to achieve more than 2 times the strength of the tensile force required to ensure safety.
It is a huge challenge to increase intensity and conductivity. As is well known, in the copper alloy material, the conductivity and intensity are inversely proportional, and the improvement of the conductivity and intensity is very difficult, so the difficulty of high-speed rail contact network wires is extremely difficult. Before the implementation of Wang Litian team project, all high-speed rail contact network wires rely on imports .
"At that time, the internationally advanced copper magnesium wire strength has reached the safety limit at 350 kilometers of the train, and it is necessary to further speed up the next generation of higher strength and higher conductivity copper-chrome zirconium-chromium zirconium contact network wires." Wang Lidian said, To achieve "China Speed", this can have to cross the past.
R & D, industrialization everything from scratch
As early as 2006, when my country began construction of high-speed rail construction, Wang Litian as a member of the expert team, started to come into this area.
"Due to high activity, high volatile characteristics of chromium zirconium alloy, resulting in the preparation of zero-defects, super long copper-chrome zirconium wires that can meet engineering needs, is known as the high-speed rail traction power supply technology ‘Crown Pearl’." Wang Lidian said that although the day, law, Germany and other countries were investigated, but did not achieve engineering applications, and the technology was closely blocked.
The foreign technical blockade made Wang Li Tian clearly saw that in order to achieve the breakthrough of my country’s high-speed rail technology, it must be self-improvement, carry out independent innovation, and make the copper chromium zirconia contact network wire domesticization, making China’s own high-strength high-guide line.
At that time, the copper magnesium wires in my country were relying on imports. It is difficult to know that the technical difficulty is difficult to develop a large copper-chrome zirconium wire. "Really everything starts from scratch, retrieving literature, can learn from the content." Wang Li Tian recalled, fortunately, the team found a Professor of Meng Liang, a high-strength material of Zhejiang University. With the help of Professor Meng Liang, used for half a year, the team developed the sample of the copper-chrome zirconium material wire in the laboratory, and the parameters indicators of the sample are very excellent, the conductivity is more than 80%, the strength Reach 620 MPa.
It is excited that Wang Li Tian found that the school laboratory research and realization of large length wire industrialization differed by hundreds of thousands of miles, and the research workload and difficulty in the laboratory only All workload and difficulty of industrialization projects are 5% -10%, and the technical difficulty of achieving industrialization is far more than team imagination.
Wang Li Tian said that all processes in the metal smelting process are basically divided into four parts. The first part is smelting technology. The second part is casting technology, and the third part is hard-changing to strengthen metal processing technology, and the fourth part is heat treatment technology.
"The first and second parts are the most important critical. At that time, we walked throughout the country, and could not find equipment that can be smelted and cast by copper-chrome zirconium wires. All of the tooling equipment must be developed by themselves." Wang Litian Say, "It can be said that the development process of wire industrialization is the process of research and development of various equipment and process processes needed to produce wires."
For example, Wang Litian said, such as smelting furnace, in order to avoid chromium zirconium alloy volatilization, the team tried a variety of process paths, and the team also selected more than a dozen tests.
"The most difficult thing is the research and development of crystallizer, when the alloy blank is cast, the surface is very rough and there is crack, and there is a gas hole, and the internal alloy component is unqualified, how to adjust the data is not used." Wang Li Tian recall It is guarded more than 1,000 degrees Celsius on more than 1,000 degrees Celsius, and many experiments failed, and many participants began to shake. Some people say that Japan has been studied for nearly 20 years, and the products have not been put into applications. How can we study it.
However, Wang Li Tian did not move, still guarded by the smelting furnace every day, finally did not have a heart, and a trial, "there is no accident in the accident", let the danger of life in the smelting site, Wang Litian, finally "smash this layer" Window paper "solves the most difficult technical problems during the development process.
Product performance world leading
In December 2010, the Beijing-Shanghai high-speed rail prior guidelines conducted a joint test and comprehensive trial, the highest operating speed of 486.1 kilometers, of which the high-strength high-spirited copper chrome zircon is not good.
"Tested, the conductivity of copper-chrome zirconium wire-produced copper-chromium-produced copper-chromium-produced production has reached 560 MPa, and the performance can be placed in the same type of products on the same period of Japan, while Europe and America has no similar type. The product is developed. "Wang Li Tian said proudly, and because our product production link is more simplified, there is a lot of costs.
At present, my country’s production of copper-chrome zirconium wires has achieved continuous extrusion, and continuously draws two tons of copper-chromium zirconium wires, and there is no defect in the middle of the long length. In order to ensure the safety of the wire, the wire also has high corrosion resistance, ablative resistance, and good high temperature characteristics. Wang Litian further explained that because my country’s high-speed railway spreads all over the motherland, some railways are covered, the sea, etc., so the corrosion resistance of the wire is very high. At the same time, friction is hot. When the train is driving at a high speed, it will rub it with the contact network wire. In general, when the temperature reaches 100 degrees Celsius, the wire strength will decrease. Our copper chrome zirconium wires increase the wire within a certain range of intensity due to the material and process, and 100 degrees. In addition, after cooling, the intensity of other alloy wires will generally fall by about 20%, while our chromium zircon-copper wire strength will only fall by about 5%, with excellent high temperature characteristics.
As technology continues to improve, today my country’s copper-chrome zirconium wires can achieve 83% of conductivity, while intensity reaches 620 MPa. "Chongqing, Chongqing to Chengdu, is now ready to be 400 kilometers, which is more than 400 kilometers more than the existing 350 km / h. High-speed rail to the requirements of various technologies." Wang Litian is full of confidence, he said, this time my country’s high-strength high-director contact network wire with independent intellectual property rights can provide strong technical support for the construction of new high-speed rails.