机械专业英语论文
机械类英语高考作文范文
机械类英语高考作文范文In recent years, with the rapid development of technology, the field of mechanical engineering has experienced tremendous growth. As a mechanical engineering major myself, I feel honored to be a part of this dynamic industry. In this essay, I would like to share my thoughts on the importance of mechanical engineering and its impact on society.First and foremost, mechanical engineering plays a crucial role in improving people's lives. From the transportation industry to the manufacturing sector, mechanical engineers are responsible for designing and developing various machines and systems that make our lives easier and more convenient. For instance, the development of the automobile industry has greatly enhanced our mobility and changed the way we travel. Mechanical engineers have contributed to the design and production of efficient, reliable, and safe vehicles, which have greatly improved transportation efficiency and reduced energy consumption.Furthermore, mechanical engineering has a significant impact on the global economy. The manufacturing industry heavily relies on mechanical engineers to design and optimize production processes, reducing costs and increasing productivity. By implementing automation and robotics in factories, mechanical engineers have revolutionized the efficiency of production lines and boosted the overall competitiveness of industries. These advancements have not only created job opportunities for the skilled workforce but also stimulated economic growth and development.Moreover, mechanical engineering tackles environmental issues bypromoting sustainable practices. As concerns about climate change and resource depletion mount, mechanical engineers have been at the forefront of developing green technologies. For example, they have contributed to the design of energy-efficient appliances and renewable energy systems. Mechanical engineers are also involved in optimizing industrial processes to reduce waste and pollution. By integrating sustainable practices into various industries, mechanical engineering is making significant strides towards a greener and more sustainable future.In addition, mechanical engineering fosters innovation and drives technological advancements. Through extensive research and development, mechanical engineers continuously strive to improve existing technologies and develop new ones. From aerospace engineering to nanotechnology, mechanical engineering encompasses a wide range of disciplines that push the boundaries of innovation. Breakthroughs in these fields not only benefit specific industries but also have a profound impact on human society as a whole.In conclusion, mechanical engineering is an essential field that influences every aspect of our lives. From transportation to manufacturing, from sustainability to innovation, mechanical engineers make significant contributions to society. As a mechanical engineering major, I am proud to be a part of this dynamic industry and am excited about the endless possibilities and opportunities it offers.。
机械专业英语文章
机械专业英语文章在机械领域里,机械专业英语的特点是专业性强、范围广,重视逻辑性和条理性,因此,翻译机械专业英语工作对翻译者的翻译技能的要求也越来越高。
下面是店铺带来的机械专业英语文章，欢迎阅读!机械专业英语文章Drilling and Drills钻削和钻头Drilling involves producing through or blind holes in a workpiece by forcing a tool, which rotates around its axis, against the workpiece.钻削就是通过迫使绕自身轴线旋转的切削刀具进入工件而在其上生成通孔或盲孔。
Consequently, the range of cutting from that axis of rotation is equal to the radius of the required hole. In practice, two symmetrical cutting edges that rotate about the same axis are employed.因此从旋转轴线开始的切削范围等于所需孔的半径。
实际上使用的是两条围绕相同轴线旋转的对称切削刃。
Drilling operations can be carried out by using either hand drills or drilling machines. The latter differ in size and construction. Nevertheless, the tool always rotates around its axis while the workpiece is kept firmly fixed. This is contrary to drilling on a lathe.钻削作业既能采用手钻也能采用钻床来实现。
机械类英语作文
Thirdly, the career prospects for mechanical engineers are vast and diverse. Graduates have the opportunity to work in industries such as automotive, aerospace, energy, and manufacturing. They are involved in the design and development of products, machinery, and systems, as well as the optimization of existing technologies. The demand for mechanical engineers is expected to grow in the coming years, particularly in emerging fields such as renewable energy and biomedical engineering.
机械工程专业英语作文150字左右
机械工程专业英语作文150字左右全文共3篇示例，供读者参考篇1As a student majoring in Mechanical Engineering, I have been fascinated by the endless possibilities that this field offers. Mechanical engineering is a diverse and exciting discipline that combines creativity with problem-solving skills. From designing cutting-edge technology to innovating new ways to improve everyday products, the opportunities in this field are endless.One of the key aspects of mechanical engineering is designing and analyzing mechanical systems. This involves understanding the principles of physics, mathematics, and materials science to create efficient and reliable machines. Whether it's designing a new automobile engine or improving the efficiency of a manufacturing plant, mechanical engineers play a crucial role in shaping the world around us.Another important aspect of mechanical engineering is research and development. Engineers in this field are constantly looking for ways to improve existing technology and develop new solutions to complex problems. This requires a combinationof technical knowledge, critical thinking, and creativity to come up with innovative solutions.In addition to designing and developing new technology, mechanical engineers also play a key role in sustainability and environmental conservation. By designing energy-efficient systems and reducing waste, engineers in this field are helping to create a more sustainable future for our planet.Overall, studying mechanical engineering has opened my eyes to the endless possibilities in this field. I am excited to continue learning and growing as an engineer, and I look forward to making a positive impact on the world through my work in mechanical engineering.篇2As a Mechanical Engineering student, I have always been fascinated by the intricate workings of machines and the process of designing and building them. The field of Mechanical Engineering encompasses a wide range of applications, from automotive and aerospace industries to robotics and manufacturing.In my studies, I have learned about various principles and theories that govern the behavior of mechanical systems, such asthermodynamics, fluid mechanics, and structural analysis. These concepts have provided me with a solid foundation for understanding how machines operate and how they can be improved or optimized.One of the key skills that I have developed as a Mechanical Engineering student is the ability to problem-solve and think critically. In my coursework, I have been challenged to design and build machines that meet certain specifications and performance criteria. This process has taught me how to analyze complex problems, identify potential solutions, and evaluate their effectiveness.In addition to my academic studies, I have also gained practical experience through internships and hands-on projects. These experiences have allowed me to apply the knowledge and skills that I have learned in the classroom to real-world problems. Through these opportunities, I have developed a deeper understanding of the challenges and opportunities that exist in the field of Mechanical Engineering.Overall, I am excited about the potential that a career in Mechanical Engineering holds. I look forward to continuing my studies and gaining more experience in the field, so that I cancontribute to the design and development of innovative machines that improve the lives of people around the world.篇3Mechanical Engineering is a diverse and challenging field that involves the design, development, and manufacturing of mechanical systems, components, and machines. It plays a crucial role in various industries including automotive, aerospace, manufacturing, and energy.One of the key aspects of mechanical engineering is the ability to apply scientific and mathematical principles to solve real-world problems. This involves designing and analyzing mechanical systems using computer-aided design (CAD) software, performing simulations to optimize performance, and conducting tests to ensure reliability and safety.Mechanical engineers are also responsible for creating detailed technical drawings and specifications, overseeing the manufacturing process, and collaborating with other professionals such as designers, technicians, and project managers. In addition, they must stay up-to-date with the latest advancements in technology and industry trends to remain competitive in the global market.Overall, mechanical engineering is a dynamic and rewarding profession that offers opportunities for innovation, creativity, and career growth. Whether you are interested in developing sustainable energy solutions, designing cutting-edge machinery, or improving manufacturing processes, a degree in mechanical engineering can open doors to a wide range of exciting and fulfilling career paths.。
机械方面的英语作文
机械方面的英语作文Machines have been an integral part of human civilization for centuries, transforming the way we live, work, and interact with the world around us. From the earliest tools and devices used by our ancestors to the highly sophisticated and complex machines of the modern era, the evolution of machinery has been a testament to the ingenuity and problem-solving abilities of the human mind.At the heart of every machine lies a fundamental principle of physics or engineering, a carefully designed system of components working in harmony to achieve a specific task. Whether it's a simple lever or a complex robotic arm, the underlying mechanics that govern the operation of a machine are a fascinating study in the interplay of forces, energy, and motion.One of the most significant advancements in the field of machines has been the development of automation and robotics. Automated systems, equipped with sensors, microprocessors, and sophisticated control algorithms, are now capable of performing a wide range of tasks with remarkable precision and efficiency. From assembly linesin manufacturing plants to self-driving cars on our roads, these intelligent machines are revolutionizing the way we approach various industries and everyday activities.The rise of robotics has also had a profound impact on the field of medicine. Robotic surgical systems, for instance, allow surgeons to perform complex procedures with unparalleled accuracy and dexterity, leading to improved patient outcomes and reduced recovery times. Similarly, the use of robotic prosthetics and exoskeletons is empowering individuals with physical disabilities, restoring their mobility and independence.Beyond the realm of industrial and medical applications, machines have also found their way into our homes and personal lives. Household appliances, from washing machines to smart home assistants, have become ubiquitous, simplifying our daily tasks and enhancing our quality of life. The integration of machine learning and artificial intelligence into these devices has further expanded their capabilities, allowing them to adapt to our preferences and anticipate our needs.One of the most exciting developments in the world of machines is the ongoing exploration of renewable energy technologies. Wind turbines, solar panels, and hydroelectric generators are just a few examples of the innovative machines that are harnessing the powerof nature to generate clean, sustainable energy. As the global demand for energy continues to grow, these eco-friendly machines are playing a crucial role in the transition towards a more sustainable future.The impact of machines on our society extends far beyond their practical applications. The design and engineering of machines have also inspired artistic and creative endeavors, with many artists and designers incorporating machine-like elements into their work. From the intricate steampunk aesthetic to the minimalist elegance of Bauhaus-inspired designs, the interplay between form and function in machines has captivated the imagination of countless individuals.As we look to the future, the continued advancement of machine technology promises even more remarkable innovations. The integration of artificial intelligence, quantum computing, and nanotechnology into machine design is expected to lead to breakthroughs in fields ranging from healthcare to space exploration. Imagine a world where machines can autonomously diagnose and treat medical conditions, or where nanoscale robots can be deployed to repair and maintain our infrastructure at the molecular level.However, with the rapid progress of machine technology comes the need to address the ethical and social implications of these advancements. Questions surrounding the impact of automation onemployment, the potential risks of intelligent machines, and the responsible development of emerging technologies must be carefully considered and addressed.In conclusion, the history of machines is a testament to the ingenuity and problem-solving abilities of the human mind. From the earliest tools to the most advanced robotic systems, the evolution of machinery has transformed the way we live, work, and interact with the world around us. As we continue to push the boundaries of what is possible, it is crucial that we approach the development of machine technology with a deep understanding of its potential impact and a commitment to using it in a responsible and ethical manner. By embracing the power of machines while remaining mindful of their societal implications, we can harness the incredible potential of these technological marvels to create a better future for all.。
机械类英语论文翻译.doc
机械类英语论文翻译.doc轴承内径 bearing bore diameter轴承寿命 bearing life轴承套圈 bearing ring轴承外径 bearing outside diameter轴颈 journal轴瓦、轴承衬 bearing bush轴端挡圈 shaft end ring轴环 shaft collar轴肩 shaft shoulder轴角 shaft angle轴向 axial direction轴向齿廓 axial tooth profile轴向当量动载荷 dynamic equivalent axial load轴向当量静载荷 static equivalent axial load轴向基本额定动载荷 basic dynamic axial load rating轴向基本额定静载荷 basic static axial load rating 轴向接触轴承 axial contact bearing轴向平面 axial plane轴向游隙 axial internal clearance轴向载荷 axial load轴向载荷系数 axial load factor轴向分力 axial thrust load主动件 driving link主动齿轮 driving gear主动带轮 driving pulley转动导杆机构 whitworth mechanism转动副 revolute (turning) pair转速 swiveling speed rotating speed转动关节 revolute joint转轴 revolving shaft转子 rotor转子平衡 balance of rotor装配条件 assembly condition锥齿轮 bevel gear锥顶 common apex of cone锥距 cone distance锥轮 bevel pulley; bevel wheel锥齿轮的当量直齿轮 equivalent spur gear of the bevel gear 锥面包络圆柱蜗杆 milled helicoids worm准双曲面齿轮 hypoid gear子程序 subroutine子机构 sub-mechanism自动化 automation自锁 self-locking自锁条件 condition of self-locking自由度 degree of freedom, mobility。
机械专业英语论文
The original126 kV Vacuum Circuit Breaker Debuted in ChinaJimei Wang（Department of Electrical Engineering, Xi'an Jiaotong University Xi'an 710049, Shaanxi Province, P.R. China）Abstract- A single break 126 kV vacuum circuit breaker debuted in China is introduced.Configuration of 126 kV vacuum circuit breaker and configuration of its electrode are illustrated. Particularly, silicone oil is used as external insulation of vacuum interrupters. Heat radiators are designed for raising rated current. Permanent magnet actuators with long stroke are developed for improving performance of the vacuum circuit breaker.I. INTRODUCTIONA project of researching and developing 126 kVsingle break vacuum circuit breaker is being done by cooperation of Xi'an Jiaotong University, vacuum interrupter manufacturers and vacuum switchgear factories in China. It took nearly sixteen months to finish a prototype. Its main technical objectives are shown in Table 1.II. CONFIGURATION OF 126 kV VACUUM CIRCUIT BREAKERThe 126 kV single break vacuum circuit breaker prototype is shown in Fig. 1, which shows three vacuum interrupters are individually assembled in each porcelain bushing 1. Porcelain insulating support 2 is mounted on a horizontal steel bracket 3, and three permanent magnet actuators 4 are separately installed at the end of each insulating porcelain insulating support 2, which are electronically controlled by control box 5, thus synchronization switching could be realized. Two steel vacuum interrupter that isassembled in porcelain bushing,2-porcelain insulation supporters, 3-horizontal steel bracket,4-permanent magnetic actuator, 5-control box, 6-steel supporting stand, 7-steel base supporting stands 6 are welded between horizontal steel bracket 3 and steel base 7. The vacuum circuit breaker is fixed on a cement block. The distance between vacuum interrupters is 1700 mm and the total height of the breaker is approximately 5000 mm.III. ELECTRODE ANALYSISA. Axial magneticfield electrode-Type AConfiguration of type A axial magnetic field (AMF) electrode is shown in Fig.2.J1' Magnetic field is generated with current passing through coils and it applies on vacuum arc, which is shown in Fig.3. The axial magnetic flux density distribution on intermediate plane of contact gap at current peak is shown in Fig.4. It showed that maximum axial magnetic flux on the plane is 0.205 T at current peak with current 4OkA rms, contact diameter 100mm and contact gap 60mm. A synthetic circuit test showed that a vacuum interrupter prototype with the type A AMF electrode successfully interrupted a 4OkA rms short circuit current.B. Axial magnetic field electrode-Type BFig.5 shows configuration of type B AMF electrode. 21 Current flows through conducting rod 1, then it goes one round in coil 2 and it enters contact 3. By passing through arc, current flows through counterpart contact 4, coil 5 and rod 6. AMF is generated with current passing through coil 2 and coil 5, and its distribution on intermediate plane of contact gap at current peak is shown in Fig. 6. The maximum axial magnetic flux density on the plane at current peak is 0.356 T with current 40 kA rms, contact diameter 100mm and contact gap 60mm, which is 7400 higher than that of type A AMF electrode. Synthetic circuit test also proved that a vacuum interrupter prototype with type B electrode can successfully interrupt a 40 kA rms current.C. Axial magnetic electrode-Type CFig.7 shows configuration of type C AMF electrode [3].It is a bipolar AMF electrode. As shown in Fig. 8, current passes through a conducting arm, then it divides into 2 branches in a coil. After that current goes into contact plate and it passes through 2 vacuum arc columns. Thereafter it enters counterpart contact plate, 2 coil branches and conducting arm. So the induced magnetic field have opposite directions at 2 sides of conducting rods. The maximum axial magnetic flux density on intermediateplane of contact gap at current peak is 0.202 T with current 40 kA rms, contact diameter 100 mm and contact gap 60 mm.IV. SILICONE OIL POURING TECHNOLOGYSF6 is an external insulation candidate in high voltage vacuum circuit breaker. Considering its greenhouse effects, silicone oil was tried as an replacement of SF6 as external insulation of 126 kV vacuum circuit breaker, as suggested by Okubo and Yanabu.41 Silicone oil is a kind of transparent liquids. Its pouring technology is as following:1) To clean porcelain bushing cavity with distilled water and then use 100 00 ethyl alcohol;2) To Vacuumize the porcelain bushing cavity as illustrated in Fig.9. First, open the vacuum valve to vacuumize the cavity to 0.2 Pa. Second, keep vacuum degree at 0.2-0.3 Pa and gradually open the silicone oil valve and let silicone oil freely flow in the cavity till reaching a specified height level, then close the vacuum valve. Third, reopen the vacuum valve to vacuumize the rest space over the oil to 0.5 Pa. Finally, close the vacuum valve and open the N2 gas valve to charge N2 into the space till to 1 Pa.3) The success of oil pouring technology can be examined by checking the N2 pressure at normal position or not with observing the gauge after 24 hours.V. RESEARCH ON RAISING RATED CURRENTRated current of 126 kV vacuum circuit breaker shown in Fig.1 is 1600 A rms. To raise its rated current, heat radiators are installed on the breaker to improve its rated current level. Fig. 10 shows the layout of heat radiators attached to this breaker. Temperature rise was measured for the improved 126kV vacuum circuit breaker prototype at an outlet terminal, as shown in Fig. 11. Test results showed that temperature rise at the outlet terminal was 30 K with rated current 2000 A rms, which meets the requirements of Chinese standard. An additional test for temperature rise at rated current 2000 1.2=2400 A shows that it still satisfies the Chinese standard and IEC standard. This showed that rated current was increased from 1600A to 2000 A by the heat radiators technology.VI. DEVELOPMENT OF HIGH STROKE PERMANENT MAGNET ACTUATOR Construction of permanent magnet actuator is quite simple. Its parts number is only 25-40 00 of spring type actuator. Besides, it has merits of high reliable performance and long mechanical life that is approximately 100,000 operations. Since permanent magnet actuator appeared on the market, it has drawn a common interest in vacuum circuit breakers. We developed a high stroke permanent magnet actuator for 126 kV vacuum circuit breaker. Its contact stroke is 60mm and average opening velocity is 3.5-4 m/s. Moreover, synchronization switching can be realized by permanent magnet actuator that can further improve performance of high voltage vacuum circuit breaker. Because performance of permanent magnet actuator is stable, it can be used to control the contacts of vacuumcircuit breaker, which open or close at about 500s prior to current zero. With much lowercurrent vacuum arc is easy to extinguish. By my experience this may raise the rated short circuit breaking current by 20 -25%.And in closing operation, rush current can be reduced to nearly zero.VII. CONCLUSIONSDesign features of single break 126 kV vacuum circuit breaker debuted in China is introduced, which include:1) Silicon oil is used as external insulation of vacuum interrupters.2) Rated current of the vacuum circuit breaker was raised to 2000 A with heat radiators.3) Synchronization switching can be realized by permanent magnet actuator.译文中国首个126KV真空断路器王季梅（西安交通大学电器工程学院，中国西安，710049）摘要：本文介绍了中国首个126KV单断真空断路器，描述了126KV真空断路器的机构及其电极构造。
机械类英语论文及翻译翻译
High-speed millingHigh-speed machining is an advanced manufacturing technology, different from the traditional processing methods. The spindle speed, cutting feed rate, cutting a small amount of units within the time of removal of material has increased three to six times. With high efficiency, high precision and high quality surface as the basic characteristics of the automobile industry, aerospace, mold manufacturing and instrumentation industry, such as access to a wide range of applications, has made significant economic benefits, is the contemporary importance of advanced manufacturing technology. For a long time, people die on the processing has been using a grinding or milling EDM (EDM) processing, grinding, polishing methods. Although the high hardness of the EDM machine parts, but the lower the productivity of its application is limited. With the development of high-speed processing technology, used to replace high-speed cutting, grinding and polishing process to die processing has become possible. To shorten the processing cycle, processing and reliable quality assurance, lower processing costs.1 One of the advantages of high-speed machiningHigh-speed machining as a die-efficient manufacturing, high-quality, low power consumption in an advanced manufacturing technology. In conventional machining in a series of problems has plagued by high-speed machining of the application have been resolved.1.1 Increase productivityHigh-speed cutting of the spindle speed, feed rate compared withtraditional machining, in the nature of the leap, the metal removal rate increased 30 percent to 40 percent, cutting force reduced by 30 percent, the cutting tool life increased by 70% . Hardened parts can be processed, a fixture in many parts to be completed rough, semi-finishing and fine, and all other processes, the complex can reach parts of the surface quality requirements, thus increasing the processing productivity and competitiveness of products in the market.1.2 Improve processing accuracy and surface qualityHigh-speed machines generally have high rigidity and precision, and other characteristics, processing, cutting the depth of small, fast and feed, cutting force low, the workpiece to reduce heat distortion, and high precision machining, surface roughness small. Milling will be no high-speed processing and milling marks the surface so that the parts greatly enhance the quality of the surface. Processing Aluminum when up Ra0.40.6um, pieces of steel processing at up to Ra0.2 ~ 0.4um.1.3 Cutting reduce the heatBecause the main axis milling machine high-speed rotation, cutting a shallow cutting, and feed very quickly, and the blade length of the workpiece contacts and contact time is very short, a decrease of blades and parts of the heat conduction. High-speed cutting by dry milling or oil cooked up absolute (mist) lubrication system, to avoid the traditional processing tool in contact with the workpiece and a lot of shortcomings to ensure that the tool is not high temperature under the conditions of work, extended tool life.1.4 This is conducive to processing thin-walled partsHigh-speed cutting of small cutting force, a higher degree of stability, Machinable with high-quality employeescompared to the company may be very good, but other than the company's employees may Suanbu Le outstanding work performance. For our China practice, we use the models to determine the method of staff training needs are simple and effective. This study models can be an external object, it can also be a combination of internal and external. We must first clear strategy for the development of enterprises. Through the internal and external business environment and organizational resources, such as analysis, the future development of a clear business goals and operational priorities. According to the business development strategy can be compared to find the business models, through a comparative analysis of the finalization of business models. In determining business models, a, is the understanding of its development strategy, or its market share and market growth rate, or the staff of the situation, and so on, according to the companies to determine the actual situation. As enterprises in different period of development, its focus is different, which means that enterprises need to invest the manpower and financial resources the focus is different. So in a certain period of time, enterprises should accurately selected their business models compared with the departments and posts, so more practical significance, because the business models are not always good, but to compare some aspects did not have much practical significance, Furthermore This can more fully concentrate on the business use of limited resources. Identify business models, and then take the enterprise of the corresponding departments and staff with the business models for comparison, the two can be found in the performance gap, a comparative analysis to find reasons, in accordance with this business reality, the final identification of training needs. The cost of training is needed, if not through an effective way to determine whether companies need to train and the training of the way, but blind to training, such training is difficult to achieve the desired results. A comparison only difference between this model is simple and practical training.1.5 Can be part of some alternative technology, such as EDM, grinding high intensity and high hardness processingHigh-speed cutting a major feature of high-speed cutting machine has the hardness of HRC60 parts. With the use of coated carbide cutter mold processing, directly to the installation of a hardened tool steel processing forming, effectively avoid the installation of several parts of the fixture error and improve the parts of the geometric location accuracy. In the mold of traditional processing, heat treatment hardening of the workpiece required EDM, high-speed machining replace the traditional method of cutting the processing, manufacturing process possible to omit die in EDM, simplifying the processing technology and investment costs .High-speed milling in the precincts of CNC machine tools, or for processing centre, also in the installation of high-speed spindle on the general machine tools. The latter not only has the processing capacity of general machine tools, but also for high-speed milling, a decrease of investment in equipment, machine tools increased flexibility. Cutting high-speed processing can improve the efficiency, quality improvement, streamline processes, investment and machine tool investment and maintenance costs rise, but comprehensive, can significantly increase economic efficiency.2 High-speed millingHigh-speed milling the main technical high-speed cutting technology is cutting the development direction of one of it with CNC technology, microelectronic technology, new materials and new technology, such as technology development to a higher level. High-speed machine tools and high-speed tool to achieve high-speed cutting is the prerequisite and basic conditions, in high-speed machining in the performance of high-speed machine tool material of choice and there are strict requirements.2.1 High-speed milling machine in order to achieve high-speed machiningGeneral use of highly flexible high-speed CNC machine tools, machining centers, and some use a dedicated high-speed milling, drilling. At the same time a high-speed machine tool spindle system and high-speed feeding system, high stiffness of the main characteristics of high-precision targeting and high-precision interpolation functions, especially high-precision arc interpolation function. High-speed machining systems of the machine a higher demand, mainly in the following areas:General use of highly flexible high-speed CNC machine tools, machining centers, and some use a dedicated high-speed milling, drilling. At the same time a high-speed machine tool spindle system and high-speed feeding system, high stiffness of the main characteristics of high-precision targeting and high-precision interpolation functions, especially high-precision arc interpolation function. High-speed machining systems of the machine a higher demand, mainly in the following areas:High-speed milling machine must have a high-speed spindle, the spindle speed is generally 10000 ~ 100000 m / min, power greater than 15 kW. But also with rapid speed or in designated spots fast-stopping performance. The main axial space not more than 0 .0 0 0 2 m m. Often using high-speed spindle-hydrostatic bearings, air pressure-bearing, mixed ceramic bearings, magnetic bearing structure of the form. Spindle cooling general use within the water or air cooled.High-speed processing machine-driven system should be able to provide 40 ~ 60 m / min of the feed rate, with good acceleration characteristics, can provide 0.4 m/s2 to 10 m/s2 acceleration and deceleration. In order to obtain good processing quality, high-speed cutting machines must have a high enough stiffness. Machine bed material used gray iron, can also add a high-damping base of concrete, to prevent cutting tool chatter affect the quality of processing. A high-speed data transfer rate, can automatically increase slowdown. Processing technology to improve the processing and cutting tool life. At present high-speed machine tool manufacturers, usually in the general machine tools on low speed, the feed of the rough and then proceed to heat treatment, the last in the high-speed machine on the half-finished and finished, in improving the accuracy and efficiency at the same time, as far as possible to reduce processing Cost.2.2 High-speed machining toolHigh-speed machining tool is the most active one of the important factors, it has a direct impact on the efficiency of processing, manufacturing costs and product processing and accuracy. Tool in high-speed processing to bear high temperature, high pressure, friction, shock and vibration, such as loading, its hardness and wear-resistance, strength and toughness, heat resistance, technology and economic performance of the basic high-speed processing performance is the key One of the factors. High-speed cutting tool technology development speed, the more applications such as diamond (PCD), cubic boron nitride (CBN), ceramic knives, carbide coating, (C) titanium nitride Carbide TIC (N) And so on. CBN has high hardness, abrasion resistance and the extremely good thermal conductivity, and iron group elements between the great inertia, in 1300 ℃ would not have happened significant role in the chemical, also has a good stability. The experiments show that with CBN cutting toolHRC35 ~ 67 hardness of hardened steel can achieve very high speed. Ceramics have good wear resistance and thermal chemical stability, its hardness, toughness below the CBN, can be used for processing hardness of HRC <5 0 parts. Carbide Tool good wear resistance, but the hardness than the low-CBN and ceramics. Coating technologyused knives, cutting tools can improve hardness and cutting the rate, for cutting HRC40 ~ 50 in hardness between the workpiece. Can be used to heat-resistant alloys, titanium alloys, hightemperature alloy, cast iron, Chungang, aluminum and composite materials of high-speed cutting Cut, the most widely used. Precision machining non-ferrous metals or non-metallic materials, or the choice of polycrystalline diamond Gang-coated tool.2.3 High-speed processing technologyHigh-speed cutting technology for high-speed machining is the key. Cutting Methods misconduct, will increase wear tool to less than high-speed processing purposes. Only high-speed machine tool and not a good guide technology, high-speed machining equipment can not fully play its role. In high-speed machining, should be chosen with milling, when the milling cutter involvement with the workpiece chip thickness as the greatest, and then gradually decreased. High-speed machining suitable for shallow depth of cut, cutting depth of not more than 0.2 mm, to avoid the location of deviation tool to ensure that the geometric precision machining parts. Ensure that the workpiece on the cutting constant load, to get good processing quality. Cutting a single high-speed milling path-cutting mode, try not to interrupt the process and cutting tool path, reducing the involvement tool to cut the number to be relatively stable cutting process. Tool to reduce the rapid change to, in other words when the NC machine tools must cease immediately, or Jiangsu, and then implement the next step. As the machine tool acceleration restrictions, easy to cause a waste of time, and exigency stop or radical move would damage the surface accuracy. In the mold of high-speed finishing, in each Cut, cut to the workpiece, the feed should try to change the direction of a curve or arc adapter, avoid a straight line adapter to maintain the smooth process of cutting.3 Die in high-speed milling processing ofMilling as a highly efficient high-speed cutting of the new method,inMould Manufacturing has been widely used. Forging links in the regular production model, with EDM cavity to be 12 ~ 15 h, electrodes produced 2 h. Milling after the switch to high-speed, high-speed milling cutter on the hardness of HRC 6 0 hardened tool steel processing. The forging die processing only 3 h20min, improve work efficiency four to five times the processing surface roughness of Ra0.5 ~ 0.6m, fully in line with quality requirements.High-speed cutting technology is cutting technology one of the major developments, mainly used in automobile industry and die industry, particularly in the processing complex surface, the workpiece itself or knives rigid requirements of the higher processing areas, is a range of advanced processing technology The integration, high efficiency and high quality for the people respected. It not only involves high-speed processing technology, but also including high-speed processing machine tools, numerical control system, high-speed cutting tools and CAD / CAM technology. Die-processing technology has been developed in the mold of the manufacturing sector in general, and in my application and the application of the standards have yet to be improved, because of its traditional processing with unparalleled advantages, the future will continue to be an inevitable development of processing technology Direction.4 Numerical control technology and equipping development trend and countermeasureEquip the engineering level, level of determining the whole national economy of the modernized degree and modernized degree of industry, numerical control technology is it develop new developing new high-tech industry and most advanced industry to equip (such as information technology and his industry, biotechnology and hisindustry, aviation, spaceflight, etc. national defense industry) last technology and getting more basic most equipment. Marx has ever said "the differences of different economic times, do not lie in what is produced, and lie in how to produce, produce with some means of labor ". Manufacturing technology and equipping the most basic means of production that are that the mankind produced the activity, and numerical control technology is nowadays advanced manufacturing technology and equips the most central technology. Nowadays the manufacturing industry all around the world adopts numerical control technology extensively, in order to improve manufacturing capacity and level, improve the adaptive capacity and competitive power to the changeable market of the trends. In addition every industrially developed country in the world also classifies the technology and numerical control equipment of numerical control as the strategic materials of the country, not merely take the great measure to develop one's own numerical control technology and industry, and implement blockading and restrictive policy to our country in view of " high-grade, precision and advanced key technology of numerical control " and equipping. In a word, develop the advanced manufacturing technology taking numerical control technology as the core and already become every world developed country and accelerate economic development in a more cost-effective manner, important way to improve the overall national strength and national position.Numerical control technology is the technology controlled to mechanical movement and working course with digital information, integrated products of electromechanics that the numerical control equipment is the new technology represented by numerical control technology forms to the manufacture industry of the tradition and infiltration of the new developing manufacturing industry, namely the so-called digitization is equipped, its technological range covers a lot of fields: (1)Mechanical manufacturing technology; (2)Information processing, processing, transmission technology; (3)Automatic control technology; (4)Servo drive technology; (5)Technology of the sensor; (6)Software engineering ,etc..Development trend of a numerical control technologyThe application of numerical control technology has not only brought the revolutionary change to manufacturing industry of the tradition, make the manufacturing industry become the industrialized symbol , and with the constant development of numerical control technology and enlargement of the application, the development of some important trades (IT , automobile , light industry , medical treatment ,etc. ) to the national economy and the people's livelihood of his plays a more and more important role, because the digitization that these trades needed to equip has already been the main trend of modern development. Numerical control technology in the world at present and equipping the development trend to see, there is the following several respect [1- ] in its main research focus.5 A high-speed, high finish machining technology and new trend equippedThe efficiency, quality are subjavanufacturing technology. High-speed, high finish machining technology can raise the efficiency greatly , improve the quality and grade of the products, shorten production cycle and improve the market competitive power. Japan carries the technological research association first to classify it as one of the 5 great modern manufacturing technologies for this, learn (CIRP) to confirm it as the centre in the 21st century and study one of the directions in international production engineering.In the field of car industry, produce one second when beat such as production of 300,000 / vehicle per year, and many variety process it is car that equip key problem that must be solved one of; In the fields of aviation and aerospace industry, spare parts of its processing are mostly the thin wall and thin muscle, rigidity is very bad, the material is aluminium or aluminium alloy, only in a situation that cut the speed and cut strength very small high,could process these muscles, walls. Adopt large-scale whole aluminium alloy method that blank " pay empty " make the wing recently, such large-scale parts as the fuselage ,etc. come to substitute a lot of parts to assemble through numerous rivet , screw and other connection way, make the intensity , rigidity and dependability of the component improved. All these, to processing and equipping the demand which has proposed high-speed, high precise and high flexibility.According to EMO2001 exhibition situation, high-speed machining center is it give speed can reach 80m/min is even high , air transport competent speed can up to 100m60m/min of speed, it is 100m/min to be fast, the acceleration reaches 2g, the rotational speed of the main shaft has already reached 60 000r/min. Processing a thin wall of plane parts, spend 30min only, and same part general at a high speed milling machine process and take 3h, the ordinary milling machine is being processed to need 8h; The speed and acceleration of main shaft of dual main shaft lathes of Germany DMG Company are up to 120000r/mm and 1g.In machining accuracy, the past 10 years, ordinary progression accuse of machining accuracy o f lathe bring 5μm up to from 10μm already, accurate grades of machining center from 3～5μm, rise to 1～1.5μm, and ultraprecision machining accuracy is it enter nanometer grade to begin already (0.01μm).In dependability, MTBF value of the foreign numerical control device has already reached above 6 000h, MTBF value of the servo system reaches above 30000h, demonstrate very high dependability .In order to realize high-speed, high finish machining, if the part of function related to it is electric main shaft, straight line electrical machinery get fast development, the application is expanded further .5.2 Link and process and compound to process the fast development of the lathe in 5 axesAdopt 5 axles to link the processing of the three-dimensional curved surface part, can cut with the best geometry form of the cutter , not only highly polished, but also efficiency improves by a large margin . It is generally acknowledged, the efficiency of an 5 axle gear beds can equal 2 3 axle gear beds, is it wait for to use the cubic nitrogen boron the milling cutter of ultra hard material is milled and pared at a high speed while quenching the hard steel part, 5 axles link and process 3 constant axles to link and process and give play to higher benefit. Because such reasons as complicated that 5 axles link the numerical control system , host computer structure that but go over, it is several times higher that its price links the numerical control lathe than 3 axles , in addition the technological degree of difficulty of programming is relatively great, have restricted the development of 5 axle gear beds.At present because of electric appearance of main shaft, is it realize 5 axle complex main shaft hair structure processed to link greatly simplify to make, it makes degree of difficulty and reducing by a large margin of the cost, the price disparity of the numerical control system shrinks. So promoted 5 axle gear beds of head of complex main shaft and compound to process the development of the lathe (process the lathe including 5).At EMO2001 exhibition, new Japanese 5 of worker machine process lathe adopt complex main shaft hair, can realize the processing of 4 vertical planes and processing of the wanton angle, make 5 times process and 5 axles are processed and can be realized on the same lathe, can also realize the inclined plane and pour the processing of the hole of awls. Germany DMG Company exhibits the DMUVoution series machining center, but put and insert and put processing and 5 axles 5 times to link and process in once, can be controlled by CNC system or CAD/CAM is controlled directly or indirectly.5Japan, ONC (Open Numerical Control System) of China, etc.. The numerical control system melts to become the future way of the numerical control system open. The so-called open numerical control system is the development ofthe numerical control system can be on unified operation platform, face the lathe producer and end user, through changing, increasing or cutting out the structure target(numerical control function), form the serration, and can use users specially conveniently and the technical know-how is integrated in the control system, realize the open numerical control system of different variety , different grade fast, form leading brand products with distinct distinction. System structure norm of the open numerical control system at present, communication norm , disposing norm , operation platform , numerical control systematic function storehouse and numerical control systematic function software development ,etc. are the core of present research.The networked numerical control equipment is a new light spot of the fair of the internationally famous lathe in the past two years. Meeting production line , manufacture system , demand for the information integration of manufacturing company networkedly greatly of numerical control equipment, realize new manufacture mode such as quick make , fictitious enterprise , basic Entrance that the whole world make too. Some domestic and international famous numerical control lathes and systematic manufacturing companies of numerical control have all introduced relevant new concepts and protons of a machine in the past two years, if in EMO2001 exhibition, " Cyber Production Center " that the company exhibits of mountain rugged campstool gram in Japan (Mazak) (intellectual central production control unit, abbreviated as CPC); The lathe company of Japanese big Wei (Okuma ) exhibits " IT plaza " (the information technology square , is abbreviated as IT square ); Open Manufacturing Environment that the company exhibits of German Siemens (Siemens ) (open the manufacturing environment, abbreviated as OME),etc., have reflected numerical control machine tooling to the development trend of networked direction.5.4 Pay attention to the new technical standard, normal setting-up5.4.1 system of China too in 2000.5.4.2 About the numerical control standardThe numerical control standard is a kind of trend of information-based development of manufacturing industry. Information exchange among 50 years after numerical control technology was born was all because of ISO6983 standard, namely adopt G, M code describes how processes, its essential characteristic faces the processing course, obviously, he can't meet high-speed development of modern numerical control technology's needs more and more already. For this reason, studying and making a kind of new CNC system standard ISO14649 (STEP-NC) in the world, its purpose is to offer a kind of neutral mechanism not depending on the concrete system, can describe the unified data model in cycle of whole life of the products, thus realize the whole manufacture process, standardization of and even each industrial field product information.The appearance of STEP-NC may be a revolution of the technological field of the numerical control, on the development and even the whole manufacturing industry of numerical control technology, will exert a far-reaching influence. First of all, STEP-NC puts forward a kind of brand-new manufacture idea, in the traditional manufacture idea, NC processes the procedures to all concentrate on individual computer. Under the new standard, NC procedure can be dispersed on Internet, this is exactly a direction of open , networked development of numerical control technology. Secondly, STEP-NC numerical control system can also reduce and process the drawing (about 75%), process the procedure to work out the time (about 35%) and process the time (about 50%) greatly.At present, American-European countries pay much attention to the research of STEP-NC, EuropeJapannumerical control at present.6 pairs of basic estimations of technology and industry development of numerical control of our countryThe technology of numerical control of our country started in 1958, the development course in the past 50 years can roughly be divided into 3 stages: The first stage is from 1958 to 1979, namely closed developing stage. In this stages, because technology of foreign countries blockade and basic restriction of terms of our country, the development of numerical control technology is comparatively slow. During "Sixth Five-Year Plan Period" , " the Seventh Five-Year Plan Period " of the country in second stage and earlier stage in " the Eighth Five-Year Plan Period ", namely introduce technology, digest and assimilate, the stage of establishing the system of production domesticization arisesing tentatively. At this stage , because of reform and opening-up and national attention , and study the improvement of the development environment and international environment, research , development and all making considerable progress in production domesticization of the products of the technology of numerical control of our country. The third stage is and during the "Ninth Five-Year Plan Period" on the later stage in "the Eighth Five-Year Plan Period" of the country, namely implement the research of industrialization, enter market competition stage. At this stage, made substantive progress in industrialization of the domestic numerical control equipment of our country. In latter stage for "the Ninth Five-Year Plan ", the domestic occupation rate of market of the domestic numerical control lathe is up to 50%, it is up to 10% too to mix the domestic numerical control system (popular).Make a general survey of the development course in the past 50 years of technology of numerical control of our country, especially through tackling key problems of 4 Five-Year Plans, all in all has made following achievements.a. Have established the foundation of the technical development of numerical control, has mastered modern numerical control technology basically. Our country has already, the numerical control host computer, basic technology of special plane and fittings grasped and driven from the numerical control system and survey basically now, among them most technology have already possessed and commercialized the foundation developed, some technology has already, industrialization commercialized.b. Have formed the industrial base of numerical control tentatively. In tackling key problems the foundation that the achievement and some technology commercialize, set up the systematic factories of numerical control with production capacity in batches such as numerical control in Central China, numerical control of the spaceflight etc.. Electrical machinery plant of Lanzhou, such factory and the first machine tool plant of Beijing , the first machine tool plant of Jinan ,etc. several numerical control host computer factories of a batch of servo systems and servo electrical machineries as the numerical control in Central China, etc.. These factories have formed the numerical control industrial base of our country basically.c. Have set up a numerical control research, development, managerial talent's basic team.Though has made considerable progress in research and development and industrialization of numerical control technology, but we will realize soberly, the research and development of the technology of advanced numerical control of our country, especially there is greater disparity in current situation and current demand of our country of engineering level in industrialization. Though very fast from watching the development of our country vertically, have disparity horizontally more than (compare foreign countries with) not merely engineering level, there is disparity too in development speed in some aspects, namely the engineering level disparity between some high-grade , precision and advanced numerical control equipment has the tendency to expand . Watch from world, estimate roughly as follows about the engineering level of numerical control of our country and industrialization level.a. On the engineering level, in probably backward 10-1 years with the advanced level in foreign countries, it is。
有关机械的英语作文
Machines and Their Impact on SocietyMachines have been a pivotal part of human civilization, revolutionizing the way we live, work, and interact withthe world. From the earliest inventions of the wheel and lever to the complex automated systems of today, mechanical devices have continuously pushed the boundaries of human capability and progress.In the early stages of human history, machines were simple tools that augmented human strength and speed, enabling us to accomplish tasks more efficiently. The wheel, for instance, revolutionized transportation by allowing for the movement of heavy loads over long distances withreduced effort. The lever, another fundamental mechanical device, allowed us to lift and move objects far beyond our natural capabilities.As time progressed, machines became more complex and specialized, catering to specific needs and industries. The Industrial Revolution marked a significant milestone in the evolution of machines, with the introduction of steam engines, textile machines, and other automated systems that transformed manufacturing and production. These machinesnot only increased productivity but also altered the social and economic landscape, leading to the urbanization of society and the emergence of new classes of workers.Today, machines have become even more sophisticated and integral to our daily lives. Robotics and automation have taken over many tasks that were once solely performed by humans, from manufacturing assembly lines to surgical procedures. Artificial intelligence and machine learning algorithms have given machines the ability to learn and adapt, enabling them to perform complex tasks with increasing accuracy and efficiency.The impact of machines on society is profound and multifaceted. On the one hand, machines have greatly improved our quality of life by reducing the burden of physical labor, increasing productivity, and enabling us to access information and services with unprecedented ease. On the other hand, the rise of machines has also led to concerns about job displacement, inequality, and theethical implications of using machines in decision-making processes.As we continue to develop and deploy more advanced machines, it is crucial that we address these challenges and ensure that the benefits of technological progress are shared widely and equitably. We must invest in education and training to help workers adapt to the changing labor market and equip them with the skills needed to thrive in a machine-driven world. We must also establish ethical frameworks and regulations to guide the development and use of machines, ensuring that they serve the interests of society and respect human values.In conclusion, machines have been a driving force of human progress and development, reshaping our world in ways that are both beneficial and challenging. As we move into the future, it is our responsibility to harness the power of machines in a way that benefits all and ensures a sustainable and inclusive society.**机械对社会的影响**机械一直是人类文明的关键组成部分，不断改变着我们的生活方式、工作方式和与世界互动的方式。
机械专业论文(英文版)
Simulation and Vibration Analysisof Shaft CracksSpectra Quest, Inc.8201 Hermitage RoadRichmond, VA 23228(804) 261-3300April, 2007Abstract: A Shaft crack is one of the most common defects in a rotor system and detection of such shaft crack is a very serious matter. In this study, shaft cracks were simulated and analyzed using SpectraQuest’s rotor Machinery Fault Simulator TM (MFS). A series of experiments were conducted to observe the behavioral changes of the cracked shaft in critical speed, 1X and 2X frequency responses. The experimental results were found to be consistent with the theoretical prediction of the shaft crack.1. INTRODUCTION A shaft crack is a slowly growing fracture of the rotor. If undetected in an operating machine, as a crack grows, the reduced cross section of the rotor will not able to withstand the dynamic loads applied to it. When this happens, the rotor will fail in a fast brittle fracture mode. The sudden failure releases a large amount of energy that is stored in the rotating system, and the rotor will fly apart. This kind of failure may cause serious injury or even death to anyoneunfortunately standing near the machine at that moment. Obviously, shaft crack detection is a very serious matter, and machines that are suspected of having a crack must be treated with the utmost caution. Cracks are initiated in the shaft in regions of high local stress. Shafts are subjected to large-scale stresses due to bending, torsion, static radial loads, constrained thermal bows, thermal shock, and residual stresses from heat treatment, welding and machine operations. All of these stresses combine to produce a local stress field that changes periodically. In a small, local region where stresses exceed the maximum that the material can withstand, a crack will form in the material. If the cyclic stresses are sufficiently high, the leading edge of the crack will slowly propagate so that the plane of the crack is perpendicular to the orientation of the tensile stress field. The geometric factors. If the rotor is subjected only to simple bending stresses, then the stress fieldwill be oriented along the long axis of the rotor, and the crack will propagate directly into and across the rotor section, forming a transverse crack. The pure torsional stress will produce a tensile stress field that is oriented at 45° relative to the shaft axis. A crack in this stress field will propagate into the rotor and tend to form a spiral on the shaft surface. Figure 1 shows these two types of cracks. In most rotor systems, the stress field contains a mixture of bending侦查丆探测观察行为变化临界的理论预测一致的破裂丆断裂未被发现横截面抵挡动态负载释放旋转的粉碎丆飞散怀疑极度的丆最大限度的开始丆发起局部应力由于扭转静态径向负载残留应力热处理焊接定期地超过充分地丆足够地前沿增殖丆传播丆传送平面垂直于方向抗应力场可拉长的丆可伸长的几何因子定向的丆以为方向的截面横向裂纹相对于and torsional stress. Bending stress, however, is usually the dominant component, thus thecrack will usually propagated into the rotor more or less as a transverse crack.Figure 1. Transverse and torsion cracks.Shaft bending stiffness is related to the shaft cross-section area. As a crack propagates acrossthe shaft, the remaining cross section becomes smaller, and the bending stiffness of the shaft decreases. This will reduce the resonance frequency as well as the critical speed of the rotor system. The reduction in shaft stiffness also causes the rotor to bow more in response to a static or dynamic load, such as a rotating unbalance. The bow is likely to change over time. As a result, it will change the effective location and magnitude of the heavy spot, which will consequently change the 1X rotor response.If a rotor with a crack has a steady, unidirectional radial load, then a strong 2X response may appear when the rotor is turning at half of any resonance speed. As a breathing crack involves both the closing and opening in one revolution, the rotor will respond at the 2X frequency. If a resonance exists at twice running speed, then the 2X vibration will be amplified.In this study, a series of tests were carried out on a SpectraQuest MFS with cracked shafts to observe their behavioral changes, including the critical speed, 1X and 2X frequency responses, compared with an intact shaft.2. EXPERIMENTAL SETUPThree experiments were designed to approach the objective of this study. They were:A. Cracked shaft simulated using FlangeB. Notched shaft with V-shape crack 1.6” from the inboard bearing housingC. Notched shaft with V-shape crack 1” from the inboard bearing housing The changes of critical speeds for the intact and cracked shafts were studied in experiments A and B. The changes of 1X and 2X frequency responses for the intact and cracked shafts were 占优势的弯曲进度丆弯曲刚度共振频率弯曲回转运动不平衡随着时间实际位置单向的径向载荷呼吸的 •C 逼真的旋转振动完整的丆未受损伤的轴承箱内侧完整的investigated in experiments B and C. The running speeds were chosen to be 2000 rpm and 4000 rpm.The tests were conducted on the rotor MFS which is illustrated in Figure 2. Four accelerometers were mounted on the inboard and outboard bearing housings in the vertical and horizontal direction, respectively. The setup of experiment A is shown in Figure 3.Figure 2 SpectraQuest’s Machinery Fault Simulator (MFS)Figure 3 shows the flange-simulated cracked shaft. It consists of two separable shafts joined atthe mating flanges. The four (4) bolts compress Belleville washers which can be loosened or tightened in a pattern to create an un-symmetric time varying stiffness and simulate the opening and closing of a transverse crack. The large disc next to the flanges provides gravityloading and a shaft bending moment. Tests were run with one, two and three bolts loosened.Figure 3. Setup for experiment A The setup for experiments B and C use a shaft with a simple 90 degree 0.150” deep notch. A small tapped hole in the center allowed a small filler piece to be clamped in the notch to vary the stiffness change due to the notch. Tests were run with the filler piece removed, partially and fully tightened.研究实施加速计垂直的水平的分别地使紧密配合不对称的横向裂纹刻痕螺纹孔加紧改变刚性变化3.EXPERIMENTAL RESULTS AND ANALYSISAll experimental data have been collected and analyzed by using SpectraQuest’s VibraQuest software package. Transient, Waterfall and Analysis tools of this software package were mainly used in this study.3.1 Change of critical speedsThe critical speed in start-up tests can be identified by using time-frequency spectrogram, time waveform, and waterfall plot of the acceleration signals, shown as Figs. 4 through 6横坐标respectively. In Fig. 5 the abscissa is time (second). The red spot where a cursor points represents the first critical. The cursor values indicates that the critical occurs at 21.7 second and 65.62 Hz. For Experiment A, the critical speeds for different cracked conditions on the shaft are listed in Table 1, where the “all bolts tight condition” condition simulates no crackon the shaft, and three-loose means the most seriously cracked condition.Figure 4. Time waveform of the start-up and cost-down test for “all bolts tight” condition.Figure 6. Waterfall plot of the start-up and coast-down in the flange-simulated crack testTable 1 Change of the critical speed in Experiment AConditions Critical speed (Hz)All bolts tight 65.62One bolt loose 65.00Two bolts loose 64.37Three bolts loose 64.37The critical speeds for different cracked conditions on the shaft in Experiment B are listed in Table 2. Intact means no crack on the shaft and “No-filler” represents the most serious crack condition. Filler fully tightened and Filler partially tightened (more serious than Filler fully tightened) stand for the middle cracked conditions.Table 2 Change of the critical speed in Experiment BCritical speed (Hz)Intact 65.00 Filler fully tightened 62.50Filler partially tightened 62.50No-filler 60.00 Both tables have demonstrated that as the crack grows, the critical speed decreases due to the reduced stiffness. The overall trend of these results matches the theory of shaft crack quite well. Figure 7 clearly shows this trend for the changes of critical speeds in different crack conditions.Figure 7. Changes of critical speeds as the crack conditions change3.2 1X and 2X frequency responseUsing the analysis functions in the VibraQuest software package, as shown in Fig. 8, it is easy to obtain the 1X and 2X frequency response for each steady-state tests in Experiments B andC. Because the critical speeds of the rotor systems were around 60 Hz to 65 Hz, when the running speed is 2000 rpm (33.33 Hz) in the tests, 2X will be close to the resonance frequency. So both the 1X and 2X components need to be analyzed. When the running speed is 4000 rpm (66.67 Hz), 1X is close to the resonance frequency and 2X will be far away from it. Therefore, only the 1X frequency response has been analyzed.Figure 8. Frequency analysis of 1X and 2X frequency responses组件Table 3. 1X and 2X frequency responses for 2000 rpm in experiment B Experiment B, 2000 rpm1X (g) 2X (g) Intact shaft9.578e-3 1.753e-2 Cracked shaft (No-filler)1.746e-22.125e-2Table 4. 1X frequency responses for 4000 rpm in Experiment BExperiment B, 4000 rpm1X (g) Intact shaft8.732e-2 Cracked shaft (No-filler)2.756e-1Table 5. 1X and 2X frequency responses for 2000 rpm in Experiment C Experiment C, 2000 rpm1X (dg) 2X (g) Intact shaft9.578e-3 1.753e-2 Cracked shaft (No-filler)2.729e-2 1.471e-2Table 6. 1X frequency responses for 4000 rpm in Experiment CExperiment C, 4000 rpm1X (g) Intact shaft8.732e-2 Cracked shaft (No-filler) 1.714e-1Tables 3 through 6 show the results of 1X and 2X frequency response for all cases of Experiments B and C. Comparing these results shows that normally the 1X and 2X frequency responses of the cracked shaft are larger than that of the intact shaft. This means the crack in the shaft has changed and amplified the 1X and 2X vibration responses. This result is consistent with the theoretical consequence about the shaft crack which has been mentioned before in the introduction.4. SUMMARY A shaft crack is a slowly growing fatigue fracture of the rotor. Damage of a crack failure can cause serious injury and therefore detection of shaft crack is very important. Shaft crack reduced the bending stiffness of the shaft due to the reduced available cross-section area. That will change the critical speed of the rotor system, and its 1X and 2X frequency response when the system is operated at one-half of a resonance frequency. All these provide the diagnosis for shaft cracks.In this study, shaft cracks were simulated and analyzed using SpectraQuest rotor Machinery Fault Simulator and the VibraQuest software package. A series of experiments were conducted to observe the behavioral changes of the cracked shaft in critical speed, 1X and 2X frequency responses. The results show that the critical speed decreased as the crack increased, and the 1X and 2X frequency response for cracked shaft increased compared with the intact shaft. Those results are consistent with the theoretical consequence of the shaft crack. 放大疲劳断裂裂纹破坏有效的诊断。
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中国首个126KV真空断路器 王季梅 （西安交通大学电器工程学院，中国西安，710049）
摘要：本文介绍了中国首个126KV单断真空断路器，描述了126KV真空断路器的机构及其电极构造。特别是，在真空开关中用硅油实现外部绝缘，设计了散热片以提高额定电流，设计大行程的永磁操作机构来提高真空断路器的性能。 1、引言 在中国，由西安交通大学、真空灭弧室制造商和真空开关厂家相互合作，已经完成了一个关于研究和开发126KV单断真空断路器的项目。建立一个原型花费了大约16个月的时间，它的主要技术指标如表1所示。
2、126KV真空断路器的结构 126KV单断真空断路器的原型如图1所示。图中，三个真空灭弧室分别组装在各自的瓷套1上。瓷绝缘支座2安装在横向钢支架3上，三个永磁操作机构4分别安装在每个瓷绝缘支架2的末端，永磁操作机构4由控制箱5进行电控，从而实现同步开关。在横向钢支架3和钢基座7之间焊接有两个钢支撑6。真空断路器安装在水泥块上。相邻真空灭弧室之间的距离是1700mm，整个断路器的高度接近5000mm. 3电极分析 3.1、A型轴向磁场电极 图2所示为A型轴向磁场电极的结构。如图3所示，在真空灭弧室中，当电流通过线圈时会产生一个磁场。在峰值电流时，分布于接触体间隙的中间面的轴向磁通密度如图4所示，图中，在峰值电流平均值为40KA、接触体直径为100mm、接触面气隙为60mm时，中间面的最大轴向磁通密度为0.205T。合成电路测试表明，配有A型电极轴向磁场的真空灭弧室模型很好的中断了一个平均电流为40KA的短路电流。
3.2、B型轴向磁场电极 图5所示为B型轴向磁场电极的结构。电流通过导引棒1流经线圈2，再进入接触圆板3，穿过圆板电流流经与之对应的圆板4、线圈5和棒6。当电流通过线圈2和线圈5时就产生了轴向磁场，峰值电流时，轴向磁场在接触气隙中间平面的分布如图6所示。图中，在峰值电流平均值为40KA、接触体直径为100mm、接触面气隙为60mm时，中间面的最大轴向磁通密度为0.356T，这比A型轴向磁场电极时增加了74%。合成电路测试表明，配有B型电极轴向磁场的真空灭弧室模型很好的中断了一个平均电流为40KA的短路电流。
3.3、C型轴向磁场电极 图7所示为C型轴向磁场电极的机构，它是一个双极轴向磁场电极。如图8所示，电流经过导引轴，分成两路通过线圈，再流到一个连接圆盘，接着通过两个真空灭弧装置，此后，电流流经与之对应的连接盘，连个线圈以及导引轴。故而，在导引轴的两旁产生方向相反的感应磁场。在峰值电流平均值为40KA、接触体直径为100mm、接触面气隙为60mm时，中间面的最大轴向磁通密度为0.202T。 4、硅油浇注技术 在高压真空断路器中，SF6是一种候选绝缘物质。考虑到其温室效应，我们采用Okubo和Yanabu的建议，尝试用硅油来替代作为126KV真空断路器的外部绝缘物质。硅油是一种透明的物质，它的浇注技术如下： 1）先用蒸馏水清洗磁套内腔，再用100%的乙醇清洗。 2）如图9所示，将磁套内腔抽成真空。首先，打开真空阀将内腔压力抽到0.2Pa；其次，保持真空度在0.2-0.3Pa的同时打开硅油阀让硅油自由的流到内腔中直到达到指定的高度；第三，再次打开真空阀将油上的剩余空间抽成0.5Pa；最后，关闭真空阀打开N2控制阀，让N2将空间的压力充至1Pa。 3）24小时之后，观察N2压力计看N2压力是否正常从而判断硅油浇注是否成功。
5、关于额定电流的研究 图1所示126KV真空断路器的的额定电流的有效值为1600A。为了提高它的有效电流，在断路器上安装了散热器，以提高它的额定电流水平。图10为本断路器的散热器的布局。 如图11所示，为了提高126KV真空断路器的性能，在出口终端测出温升。 测试结果表明，当额定电流的有效值为2000A时出口终端的温升为30K，这满足了中国的国家标准。当额定电流为2000*1.2=2400A时的额外温升测试结果表明，它既满足中国国家标准又满足ICE标准。这表明，借助于散热器技术额定电流由1600A增加到了2000A。
6、大行程永磁操作机构的开发 永磁操作机构的结构非常简单，它的组成部件数仅为传统弹簧操作机构的25-40%。此外，它还具有高可靠性和长达100000次操作寿命等优点。永磁操作机构已经出现在市场上，使用于真空断路器后得到了很多的共同好处。我们开发了一种用于126KV真空断路器的大行程真空断路器，它的行程为60mm，平均分闸速度为3.5-4m/s。 此外，永磁操作机构实现了同步操作，这进一步提高了高压真空断路器的性能。由于永磁操作机构的性能稳定，它可以用于控制分合闸时间为500us的真空断路器。当电流很低时，真空灭弧室很容易停止工作。根据我的经验，这将增加额定断路断开电压20-25%。在合闸操作时，冲击电流将减至0左右。 7、结论 本文介绍了中国首个126KV真空断路器的设计特点，即： 1）用硅油作为真空灭弧室的外部绝缘物质。 2）增设了散热器，使真空断路器的额定电流增至2000A。 3）利用永磁操作机构来实现同步开关操作。 126 kV Vacuum Circuit Breaker Debuted in China Jimei Wang （Department of Electrical Engineering, Xi'an Jiaotong University Xi'an 710049, Shaanxi Province, P.R. China）
Abstract- A single break 126 kV vacuum circuit breaker debuted in China is introduced.Configuration of 126 kV vacuum circuit breaker and configuration of its electrode are illustrated. Particularly, silicone oil is used as external insulation of vacuum interrupters. Heat radiators are designed for raising rated current. Permanent magnet actuators with long stroke are developed for improving performance of the vacuum circuit breaker. I. INTRODUCTION A project of researching and developing 126 kVsingle break vacuum circuit breaker is being done by cooperation of Xi'an Jiaotong University, vacuum interrupter manufacturers and vacuum switchgear factories in China. It took nearly sixteen months to finish a prototype. Its main technical objectives are shown in Table 1.
II. CONFIGURATION OF 126 kV VACUUM CIRCUIT BREAKER The 126 kV single break vacuum circuit breaker prototype is shown in Fig. 1, which shows three vacuum interrupters are individually assembled in each porcelain bushing 1. Porcelain insulating support 2 is mounted on a horizontal steel bracket 3, and three permanent magnet actuators 4 are separately installed at the end of each insulating porcelain insulating support 2, which are electronically controlled by control box 5, thus synchronization switching could be realized. Two steel vacuum interrupter that is assembled in porcelain bushing,2-porcelain insulation supporters, 3-horizontal steel bracket,4-permanent magnetic actuator, 5-control box, 6-steel supporting stand, 7-steel base supporting stands 6 are welded between horizontal steel bracket 3 and steel base 7. The vacuum circuit breaker is fixed on a cement block. The distance between vacuum interrupters is 1700 mm and the total height of the breaker is approximately 5000 mm.
III. ELECTRODE ANALYSIS A. Axial magneticfield electrode-Type A Configuration of type A axial magnetic field (AMF) electrode is shown in Fig.2.J1' Magnetic field is generated with current passing through coils and it applies on vacuum arc, which is shown in Fig.3. The axial magnetic flux density distribution on intermediate plane of contact gap at current peak is shown in Fig.4. It showed that maximum axial magnetic flux on the plane is 0.205 T at current peak with current 4OkA rms, contact diameter 100mm and contact gap 60mm. A synthetic circuit test showed that a vacuum interrupter prototype with the type A AMF electrode successfully interrupted a 4OkA rms short circuit current.