The accelerating effect of the hottest train speed

From 1995 to April 18, 2007, China's railways have made six major speed increases, raising the high-speed running speed of passenger trains in China from 100h/h to 2001,; M/h or above: at the same time, freight locomotives are also raised from 5000t to 100000t by single locomotive traction, or 20000T by double locomotive traction, and the speed is increased from 80 ~ 80h/h to 1201,; M/h marks that China's railway has really entered the era of high-speed passenger transport and heavy freight. In order to meet the needs of high-speed and heavy-duty railway transportation, it is bound to require rail vehicles to achieve lightweight, reduce self weight and increase load. The goal of lightweight is achieved by using new materials with high strength, high specific strength and light weight. At the same time, the goal of lightweight also promotes the development and innovation of rail vehicle welding technology

1. Requirements for auxiliary materials of rail cars for train speed increase

in order to meet the needs of high-speed and heavy load, the materials of bogie frame and car body, the two important components of rail vehicles, have undergone fundamental changes:

(1) the materials of bogie frame have been changed from traditional q2358 and other ordinary low steel to Q345C, q3458, etc., such as higher strength Q4501 pall high strength weathering steel or Q345E steel with better low temperature toughness

(2) the car body is also made of corrosion-resistant stainless steel, lighter aluminum alloy and other materials (or even all of them) to replace the traditional low-carbon. It can be said that due to the lightweight requirements brought by the development of China's railway to high-speed and heavy load in recent years, non-ferrous metals such as aluminum magnesium alloys are rapidly squeezing into the traditional black material field of rail vehicles. The quality of metal materials used in rail vehicles has changed greatly

2. Requirements of train speed increase on welding materials and equipment

in terms of fusion welding, welding materials match with the selection of structural materials, welding methods and equipment. At the same time, with the improvement of the quality, reliability and quantity requirements of rail vehicles, high-quality and efficient welding methods have also been promoted and applied. The welding methods are from manual electrode welding, T-welding, submerged arc welding to c0-1 welding, m^g welding, to automatic welding and manipulator welding. In addition to using ml 嘏 for aluminum alloy welding, some units are starting to try friction stir welding (FSW)

welding materials also range from carbon steel electrode to low alloy, high strength, high toughness electrode and stainless steel electrode: from solid core wire to gas shielded flux cored wire and self shielded flux cored wire. It is precisely because rail vehicle industrial enterprises adopt efficient welding technology, rapidly updated welding equipment, efficient welding materials and high automation level that promote the research and development of welding technology such as welding materials

3. Requirements of train Speed-up on the training and adjustment of welding technicians

railway transportation will have more and more products to adopt the requirements of high quality, high strength, lightweight, low cost and high efficiency of rail vehicles proposed by the development of spray free materials with high speed and heavy load, and the diversification of the use of metal structural materials, which have put forward more topics or/and challenges for welding technicians, and need more systematic welding theoretical knowledge Welding technicians who are familiar with factory welding and have practical experience, including welding structure designers, welding process designers, welding field service engineers and welding quality inspectors. The actual situation in the industry is that the design of welding structure cannot consider the process more, the process documents cannot guide the actual welding on site, and the problems found in the on-site process quality service cannot be included in the welding structure design drawings and process documents in time. Therefore, it is suggested that:

(1) after graduation, welding technicians should first participate in welding production in the factory workshop for about one year, be familiar with the equipment and tooling on the production site, understand the welding process and process being implemented, and master the actual skills and operation requirements of welding. (2) After that, arrange 3-4 years of on-site welding process quality service, understand the actual skill operation of welders and their mastery and implementation of welding process, and cooperate to deal with the welding structure and process problems on site

(3) the welding technicians who have been trained on the welding production site for 4 ~ 5 years must be trained in a special welding training center (such as Harbin Welding Technology Training Center) according to the unified requirements of IIW, and can only be employed after passing the examination and obtaining the certificate (such as international welding engineering'j coin IWE, etc.) to undertake the welding technology work independently

(4) among the qualified welding technicians, the enterprise arranges them in the positions of welding structure design, welding process design or welding process and quality service according to their personal characteristics and enterprise needs. Such positions are not static, and there can be exchanges, so as to comprehensively improve the comprehensive quality of welding technicians

(5) in daily work, enterprises should provide more platforms for the improvement of the ability of welding technicians, such as timely arranging welding technicians to go out for study and investigation, so as to increase their understanding of the development of today's welding technology

only in this way can we improve and standardize the quality of welding technicians, cultivate a team of engineers who are familiar with the characteristics of welding process and master the design of welding structure, and adapt to and meet the higher requirements of the rapid development of railway for the manufacturing technology of rail vehicles

4. In terms of welding quality control

after railway transportation enters high-speed and heavy load, due to the increase of speed and load, the safety and reliability problems of rail vehicles are particularly prominent, and the small quality problems in metal structure manufacturing may lead to accidents or even disasters. Therefore, higher and stricter requirements are put forward for the control of manufacturing quality, especially the control of welding quality

welding safety has always been paid great attention by welding workers. Metallurgy is easy to occur in the welding process. Its theory is relatively mature and defective or processing defects (such as cracks, pores, lack of fusion and poor shape), which will lead to premature failure of the structure in service. Due to the great changes in the structural application conditions, with the continuous emergence and application of new materials, new processes and new methods, the reliable and effective quality control means (system) we thought in the past will be required to be re evaluated to meet the requirements of today's rail vehicles. Therefore, we will improve or establish the corresponding welding quality control system from the aspects of personnel, equipment, materials, process methods and environment

enterprises that have passed the advanced quality system certification must also formulate their own manufacturing quality standards according to the product structure, prepare and strictly implement manufacturing technical standards such as welding joint details, so as to truly ensure the high-speed and heavy load requirements of rail vehicles

5. Requirements for technological innovation

in order to meet the development needs of high-speed and heavy load rail vehicles, the rail vehicle industry should innovate from the following aspects:

(1) establish an analysis system for the dynamics and fatigue of rail vehicles, especially bogie frames, to realize structural optimization and improve their safety and reliability

(2) while comprehensively promoting the use of inverter pulse controlled welding machine mic,/m^g welding, through optimization, improve the structure and joint form of aluminum alloy car body, promote the use of advanced friction stir welding (f ensures the stability of product quality SW) method; and promote the laser welding method on stainless steel car body

(3) seek to develop new metal materials with lighter weight and their processing methods, such as developing hollow extruded profiles that meet the requirements of strength and lightweight, and explore the application technology of magnesium alloy in car body and parts

(4) welding technology with high efficiency, high quality and high toughness (such as flux cored/double wire m^g welding, etc.) and manipulator and special machine welding technology are widely adopted and promoted in car bodies and bogies

(5) through cooperation with international advanced rail vehicle enterprises, the future work will include the research on improving material properties, introducing international advanced personnel training and quality management system, establishing the enterprise's own manufacturing technology standard system, and realizing the innovation of welding standard system of aluminum alloy car body, bogie frame and other products