| Numerical control machine tool is a highly mechanical and electrical integrationproduct; its development level is directly related to national economic constructionand national security and strategic position. Under the circumstances of thedevelopment of the NC machine tool technology，The numerical control machine tooltechnology of our country also has improved by leaps and bounds, but there are still aseries of the problems on the production of high-grade CNC machine tool，which，onthe whole，restrict the development of the CNC technology in China。The key featuresas an important part of NC machine tool, its level of reliability directly influences thewhole machine’s reliability level. The machining center disc-type tool changer as thepart of the key features of the NC machine tools, under the condition of existingstructures，Building test bench to study the reliability，Which has a vital significancefor improving the reliability level of the whole machine.The main contents of this paper are as follows:(1)The design of the disc-type automatic tool changer system. First of all, thedesign of the overall program of the test bench, including the process of automatictool changer and the functions of the test bench. Secondly, the test bench will bedesigned from three aspects of the mechanical structure, electrical control and processcontrol to ensure that the test bench can complete tool changer functions smoothlyand rapidly and to prepare for subsequent reliability tests.(2) The reliability test methods of the disc-type automatic tool changer. First ofall, writing the reliability testing program of the disc-type automatic tool changer,including the environment, the preparation and the requirements and so on. Secondly，giving the criterion and the counting principle of the failure of the disc-type automatictool changer. Meanwhile, dividing the fault level, and adopting the different protectivemeasures on different level of the failures. Finally, the specification of the contentscollected of the different types of data and the tabular format of these data collectedand counted.(3) The data processing and analysis of the disc-type automatic tool changer.First of all, classifying the data collected, including failure data and tool changerfrequency data. Second, Through research and analysis, the reliability of the modelsof field test and laboratory test are two parameter weibull distribution model, the model parameters and MTBF point estimate for the former is：=1257.897，=1.549,MTBF1131.4h，the later is： BYS=1167.3， BYS=1.514, MTBF1052.6h. Throughthe graphical comparison and computing laboratory tests can be found on the field testhas a certain guiding significance; Finally, A typical data processing method is given.After calculated: the changeover frequency is0.074times per minute, laboratory toolchange frequency as follows:6.0696times per minute. Frequency compared to thescene in the knife, laboratory tool change frequency is fast, is conducive to stimulatethe potential failure of tool change system.(4) Using the advantage of both to handle failure data through combining thegood visual interface of VB with the power of the calculation and the graphicsprocessing of Matlab. At the same time, considering the weibull distribution model isused differently according to the different research object in construction machinery,the two parameters Weibull distribution model and the three parameters Weibulldistribution model are developed. Meanwhile, the programming method and theexample of processing data with the software are given. |
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