New requirements for cutting tools in the producti

2022-09-21
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New requirements for cutting tools in steam turbine production

at present, the domestic steam turbine industry is generally faced with the phenomenon of a large increase in orders and a serious shortage of production capacity. The production and processing efficiency needs to be continuously improved. The massive application of efficient cutting tools undoubtedly provides a solution. Shanghai turbine Co., Ltd. is also increasing the investment and promotion of efficient cutting tools. At the same time, it is actively developing cutting tools with high technical requirements and pumps in the hydraulic system to meet the needs of gas turbine, ultra supercritical and nuclear power equipment processing

difficult to process materials

at present, in order to reduce the heat consumption of generator units, the steam pressure and temperature of steam turbines are getting higher and higher. For example, the steam pressure of million grade ultra supercritical units is as high as 26mpa, and the temperature is increased to 600 ℃; The initial temperature of class F gas turbine reaches 1300 ℃, so the requirements for part materials are higher. Because superalloys have excellent high temperature strength, thermal stability and thermal fatigue resistance. Therefore, it is more and more widely used in steam turbines and gas turbines. In this way, cutting with the original tools faces many problems

600mw supercritical unit high and intermediate pressure blade is a new material containing niobium (NB), which is difficult to process. The iron filings processed with the original tool are red, and the temperature is very high (previously, the iron filings processed without niobium materials were light blue), and the blade wear is very severe. Originally, one tool can complete the processing of one blade, but now four blades need to be replaced. In this way, not only the processing cost is high, but also the production efficiency is difficult to improve. It is urgent to update the tool materials. We have been looking for many tool suppliers to trial produce, and finally chose the indexable blade of the new material re pressed by iska. At present, the effect is good. In addition, the material of valve rod of 600MW supercritical unit has also been updated, and now GH901 high temperature nickel base alloy is used. However, RAS researchers are cooperating with Prof. Dr. Valentine P. ananikov to make materials. Deep hole processing is also facing many difficulties, and Sandvik croman's deep hole gun drill is selected

Shanghai turbine Co., Ltd. imported American ring gear milling cutter as early as 1997. At present, domestic tool suppliers are also doing it, but it is impossible to have spiral groove and rake angle. At present, we also use zero rake angle and zero spiral angle in a large number of ways, with poor cutting performance and low processing efficiency. There are symmetrical and fine grinding marks under the microscope. Our company uses the newly purchased German saacke machine tool to manufacture ring gear milling cutter with spiral angle and rake angle, and the processing efficiency can be improved by 2-3 times

high accuracy requirements

the production and processing problems of steam turbines are not only reflected in high-temperature and difficult cutting materials, but also the accuracy level of products has been improved again and again with the continuous improvement of user requirements. We must also try to achieve the accuracy requirements in production

in the gas turbine project of the National 863 plan undertaken by our company, the accuracy of wheel disc processing is very high. Its material is GH2674 iron-based superalloy. At present, the turning of wheel disc is basically realized by using the tools of Walter and iska, but the accuracy requirements of wheel disc milling are even higher, the processing is more difficult, and its pitch tolerance is required to be ± 4 μ m. At present, it is difficult for domestic tool suppliers to guarantee this accuracy. We are ready to import from Alden company of the United States. In addition, the company has also tackled key problems by introducing German saacke machine tools and Zhuoer measuring instruments. At present, the self-made wheel slot milling cutter has been able to achieve 1~5 μ Pitch tolerance of M

of course, in general, the accuracy assurance mainly depends on the equipment, but in the steam turbine processing, especially the wheel groove of the rotor, it is finally realized by the cutter. Unlike mass production in the automotive industry, steam turbine processing belongs to a single piece of small batch, and various accuracy requirements may be different. For new requirements, we can only constantly test. Generally, trade dominates exploration. If the supply cycle is tight, we can only use existing cutting tools to fight hard, and if there is enough time, we can make full use of various ways, including seeking suppliers and independent research and development. (end)

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