The development of rail transit industry
The development of the rail transit industry is inseparable from advanced manufacturing technology and equipment. The rail transit industry in the new era has many new development requirements, which also brings new opportunities to the machine tool industry.
China's rail transit has experienced a rapid development from the first speed increase in the late 1990s after the reform and opening up to the eighth-speed increase in 2011. Taking Shanghai to Nanjing as an example, it takes 4 to 5 hours to complete the whole journey before the speed increase. Currently, the fastest one only takes 1 hour, and the speed has exceeded 350 kilometers per hour. It only takes 5 hours from Shanghai to Beijing.
In 2012, SCI Verkehr, a famous German consulting organization, released a research report and announced the top 10 new manufacturing fields of rail transit equipment manufacturers in the world in 2010, and CSR jumped to the first place in the world.CSR qishuyan locomotive co., LTD is a large modern enterprise which mainly produces diesel locomotive of a trunk railway. The main models are Dongfeng 8, Dongfeng 8B, Dongfeng 11, Dongfeng 11G, HXN5 series of internal combustion engines.
The locomotive for the first six times of speed-up in China's railway is mainly DF11G diesel locomotive, which is mainly from the south. In the last two years, the speed-up in China's railway is mainly from the electric locomotive. However, the diesel locomotive still has its irreplaceable position, especially in the speed of freight locomotive. Starting from the overall situation, the demand for diesel locomotive is still quite large. At present, there are about 19,000 diesel locomotives on the whole road. In addition, high-power scheduling locomotives are in urgent need of various locomotive depots and large enterprises such as coal mine and petroleum. According to preliminary estimates, the total number of locomotives updated every year is more than 600 (excluding thousands of repaired locomotives every year).
The main parts of rail transit processing difficulty simple solutions
When it comes to rail transit machining, the main parts that are relatively difficult to process are the locomotive running parts such as car bogie and hollow axle sleeve, and the key parts of diesel engine. Locomotive diesel engine main parts complicated structure, manufacture high precision, tolerance and surface roughness requirements (precision index mostly around 5 ~ 7, roughness Ra0.4), require good interchangeability, such as the body, such as crankshaft, connecting rod, cylinder cover, the main purpose is to ensure that the locomotive running at high speed in a good reliability, high durability, high safety coefficient.
In the case of key components of a diesel engine, many of them are of a muon size accuracy that was previously unimaginable and impossible to achieve.
The main difficulties are as follows:
- high requirements for blank extrusion and non-processed surface dimensions after forming;
- balance block welding requirements are also not used in the original middle crankshaft;
- due to the welding structure of the balance block, the rotary radius of the machining equipment is increased, and the tolerance of shape and position is high;
- it is difficult to control deformation by spray cooling normalizing and final surface nitriding.
Processing and controlling deformation of thin-walled cone sleeve;
- fit 80% of 1:50 taper with flywheel flange and interchangeability;
The main processing equipment is equipped with simple
Mechanical processing is by car, milling, planing, boring, drilling, grinding and other basic processing methods, around different products, and the same product different processing procedures, people used in the past is a large number of traditional structure of a single processing function of lathe, milling machine, planer, boring machine, drilling machine, grinder and other common equipment. With the development of technology, the proportion of these common equipment has been greatly reduced, replaced by single-axis and two-axis machining mainly CNC lathe, vertical and horizontal machining center CNC machining machine tools.
With the development of machine tool products and the in-depth study of related technology, today's CNC machine tools have been flexible, composite, multi-axis linkage, high precision, high speed of the dominant position. Such as multi-axis linkage turning and milling center, boring and milling center, follow-up grinder, etc. With the development of cutting tool material and manufacturing technology, computer software technology, precision measurement technology, and fast servo drive technology, the performance of the machine tool has the characteristics of high speed, high-efficiency processing, and intelligence. In addition, in order to adapt to the user's product production needs, a number of functional mix-and-match technology and practical variety of machine tools are also produced. For example, laser and milling (DMG) knead together; Milling and grinding (Wallenberg) together and so on.
In recent years, in order to adapt to the continuous development of market demand, CSR mainly added or introduced some domestic and imported vertical, horizontal processing center (suitable for parts: connecting rod, cylinder head, etc.);Longmen type processing center (suitable for parts: body, frame, etc.);Turning and milling machining center (suitable for parts: camshaft, crankshaft);Boring and milling machining center (suitable for parts: axle box, etc.);Special grinder for crankshaft, camshaft and vertical double grinding head grinder. Processing center has a small area, one equipment can be four or five equipment functions; And high processing quality, high reliability; The advantages of low energy consumption of the operator
In addition, CNC online measurement also solves the measurement problem in the previous machining. Marposs fear-l online diameter measurement device can control the accuracy of online product processing in real-time and set the automatic alarm beyond.
At the same time, in the application of tool instruments, the accuracy of tool alignment is solved, the unqualified products are avoided and the processing efficiency is improved. The previous online measurement is to stop the operator with a vernier caliper or internal and external card according to the operator's experience control; Senior engineer (level 6 or above) is generally about 0.02mm, now the tool instrument can be accurate to the mum level, the reliability is also very high.
Application of composite cutting tools
In the 80 s, machining tools are mostly welding tools, a few non-standard tools - also welded structure. At present, there are only a few welding tools, most of the machine clamping tools, forming tools, composite tools. Especially in the processing center and other advanced equipment used tools, 100% of the standard machine clamping tools and non-standard machine clamping tools. But knives are also quite expensive. (tool consumption accounts for 5-15% of manufacturing costs.)
The machining process of composite processing technology to achieve the relatively concentrated, decrease The Times of repeated loading and unloading, and the workpiece positioning and shorten processing auxiliary time, improve the machining precision of workpiece and the production efficiency, obvious reduction in the number and the equipment, save the origin area of production line, make the output of unit area has improved significantly, and to reduce the labor intensity of workers (of course, on the other hand, need to improve workers' culture, technology, quality).
In addition, in compound processing, the use of a molding compound tool to process some coaxiality requirements of the whole system or machining some complex surface is also quite common, one is due to high precision, two is high processing efficiency. In Europe and the United States and other high-end machining field is quite common, but because the tool manufacturers in the manufacturing accuracy are still some gap, in recent years in the railway industry has not been promoted. This may be a weak point for future development.
The current situation and the corresponding problems to be solved.
The knife instrument
The tools used by each machine tool factory are not the same, the tool instrument is also different, a tool instrument is expensive to 400,000 ~ 500,000, even up to millions; Cheap also want more than 30 ~ 50 thousand, do not have tool to bring inconvenience to the processing, but every equipment has tool tool tool also brought additional burden to the user;The failure rate is also high. It often breaks down and is quite difficult to repair.-- so the good thing becomes the bad thing.
Molding (compound) tool order
Molding tool ordering cycle long, high price; Some non-standard tools take three months or longer.
Tool cost
Another important issue is the high cost of cutting tools.
With crankshaft as an example: processing a finished crankshaft, milling center on the car about 6~7 procedures, the total cost of cutting tools in about 50,000 yuan/root around, the cost of cutting tools is the original tens of times even hundreds of times. So the advantage of low labor cost is eaten up.
Practical use problem
When ordering machine tools, there is not enough communication between the two parties on process discussion, which leads to a long time span of pre-acceptance and final acceptance, and after the acceptance, there are some problems in the details (programming, tool use and foreign businessmen's understanding of drawings and process, etc.).
Rail transit and machine tool manufacturing promote mutual development
The rapid development of rail transit has indeed brought new development opportunities to the machine tool equipment industry and the corresponding tool industry. In April 2012, "the eighth China international metal processing summit BBS" was held in Nanjing. The theme of this summit BBS was "stepping into the era of overall solutions", which triggered heated discussions among experts and scholars.
At present, enterprises in the introduction of advanced machine tools and tools, combined with rail transit special products, there is a long process of digestion and absorption and consolidation.Especially for process programming, operators and even production management personnel have an unfamiliar to the initial grasp, and then ease of application of the gradual process. Therefore, how to be a good enterprise technologist, help enterprises to put the equipment and tools into use as soon as possible and produce benefits quickly -- in turn, to their own products also set up a good image, this is a new issue in front of equipment manufacturers;At the same time, how to quickly master advanced equipment technology is also a persistent problem faced by Chinese enterprise customers.
The future development of the rail transit manufacturing industry, with the development of the machine tool manufacturing industry and continue to develop. With the different needs of various industries and continue to develop. Green and diversity (meet the requirements of different users), low noise, less pollution, low fuel consumption, low emissions, meet the Tier Ⅳ emissions requirements) and has high reliability is also the goal of internal combustion engine car design and manufacturing.
