Research On The Control Technology Of Operation Reliability Of NC Machine Tools

So far, CN Machine Tools produced by our country are limited to low quality and high quality productions basically depend on importation. The reasons are various, such as low level of design, low capacity of manufacture both in machine and key-function assembly, among them the most important is the low reliability of machine tools. By statistics, the Mean Time Between Failure (MTBF) of CN Machine Tools produced by our country is about 500 hours. However, the MTBF of overseas CN Machine Tools exceed 1000 hours. So, it restricts seriously the development of CN Machine Tools. To improve the reliability level of homebred CN Machine Tools as soon as possible, this paper researched the operation reliability of CN Machine Tools. The key-factors which influence the operation reliability were discussed, and the operation reliability monitor system of CN Machine Tools was designed and developed to provide manipulation flat roof for ensure the operation reliability, as well do stably base for the improvement of the reliability of CN Machine Tools.First of all, it started with three key-factors which influenced NC Machine Tools (maintenance activity, operation state parameter, working environment-factors), and researched the influence mechanism of the operation reliability of NC Machine Tools. On the base of study data of machine tools users, the important of operation reliability which influenced by maintenance activity, operation state parameter, working environment-factors was discussed and relevant guarantee measures were put forward.Then, on the base of reliability analysis, it researched weightily the maintenance activity. On the base of traditional frequency of the failure, a method to apply the concept of failure density proportion to establish the importance level model of maintenance was proposed. The model considered not only the frequency of the failure of accessories but also the importance of the machine reliability. So users could take suitable measures through local state condition to avoid the loss of economy. While, on the base of failure data analysis, Weibull Proportional Hazards Models containing the early failure period and random failure period was constructed. This model considered the rule of the failure through time and provided believable monitoring data for maintenance. The implication of hydraulic system and tray exchange device illustrate the models are correct and useful.At last, on the base of theory analysis above, the operation reliability monitor system of NC Machine Tools which contained maintenance monitor system and operation condition monitor system was designed and developed on the system of SINUMERIK 840D with the technology of measure, electronic, computer. The process of the design and development of the system was introduced detailedly. The implication of the monitor system on THM6380 illustrates the system can not only reduce the failure of Machine Tools but also improve the reliability of Machine Tools.