{I}, valve machine tool failure analysis　　Computer technology, microelectronics technology, automatic control technology can continue to develop various technologies, so that the traditional valve machine tool technology and can not meet the increasing demand of the production process, etc., and then PLC-based valve machine tool electrical control system has been widely concerned and applied in various fields, in the field of electromechanical has a large space for development, the integration of PLC and valve machine tools, can greatly promote the automation of the numerical control system and greatly improve the efficiency of production.　　The valve machine tool should avoid injuries and damages caused by operators, machine tools and processing personnel during use, and deal with problems in time. Under normal circumstances, the valve machine tool can disconnect the emergency stop button during operation, so that the valve machine tool is in a normally closed state. After pressing the button, the electric shock will be automatically disconnected, so that the relay in the system will be interrupted, and the power supply of the mobile device can be disconnected. After connecting the PLC intermediate relay, the signal can be sent to the system to generate an emergency stop alarm, so that a reset signal is generated in the signal system.　　Overtravel limit switch has been in a loose state, the user in the operation of the valve machine tool, once the overtravel limit switch is pressed, will lead to the relay power off phenomenon, the intermediate relay of a set of normally open contacts can send emergency stop signal to the PLC input off system, at the same time, can also send overtravel alarm information to the system, the system can make a certain response according to the signal, the problem to deal with.　　In recent years, China’s industrial production in efficiency and effectiveness has been greatly improved, which is inseparable from the application of a lot of advanced technology, in the industrial production process, the development of numerical control technology has a great impact on it, among them, PLC logic processing function is constantly improving, and, in the actual application process reflects a good effect. Therefore, the design of a system that matches the electrical control system can fully consider the selection of each part, and at the same time, the role of the electrical system can also be well played.　　The frequent failure rate of valve machine tools has always been an important problem affecting the quality of valve machine tools in China. Especially in automatic production lines for mass production, the reliability of valve machine tools is valued, and its reliability is usually measured by the length of mean time between failures (expressed in MTBF).　　{2}, the characteristics of the key technology of the special machine tool for valves　　1. High performance　　At present, the main feature of the key technology of valve special machine tools is high performance, which is widely used in some difficult materials. Its materials and strength are required to have high temperature resistance, low temperature resistance, aging resistance, corrosion resistance, toughness and fatigue resistance, so CNC machining technology will be applied in the processing of some aluminum alloys, Qin alloys, composite materials, engineering ceramics and other aspects to meet its needs for high performance.　　2. Lightweight　　The processing technology of special machine tools for valves adopts an integral thin-walled structure, so it has the characteristics of light weight. Like many aviation products have relatively high requirements for lightweight, most of them have complex shapes and more components, such as those on aircraft