Development Of Reliability Test And Condition Monitoring System Of Chain-type Tool Changer

Chain-type Tool Magazine and Automatic Tool Changer (refer to Chain-typeTool Changer) is one of the key functional features which affect the reliability levelof machining center. According to statistics, foreign Chain-type Tool Changers arebetter than similar domestic products in reliability, which directly cause that thereliability of domestic machining centers can’t reach the international advancedlevel and limit the development of CNC machine tool industry. Accelerated test inlaboratory are one of effective ways to evaluate the reliability of functional featuresof CNC machine tools. We can conduct accelerated test of test bench, stimulatefaults, find the weakness link in the short term and put forward improvementsuggestion by developing test system of relevant features.This article associates with the project of Jilin Province Science andTechnology Development Plan——"Research on reliability test system of the keyfunctional features of CNC machine tools series" and develops reliability test systemof Chain-type Tool Changer. Conduct the study of condition monitoring ofChain-type Tool Changer. By taking accelerated test of test bench in laboratory wecan stimulate functional failure of Chain-type Tool Changer and collect failure data.The main contents of this article include:(1) Develop hardware system of the reliability test bench, including mechanicalsystem and electrical system. Using the mechanical spindle, together withChain-type Tool Changer completes automatic tool changing function. Takeintensity analysis on the support structure of both. Ensure concentricity of ATCarm’s axis and spindle’s axis. Design the electrical schematic of experiment systemand build electrical system. Electrical system, with PLC as the lower computer andindustrial control computer as the host computer, implements control for toolchanging process of Chain-type Tool Changer.(2) Develop control system of the reliability test bench, including controllingprogram of the lower computer and the host computer. By programming the toolchanging procedure of the lower computer PLC according to the timing diagram ofChain-type Tool Changer we can complete a whole process of tool selection and tool changing. Using Visual C++software to write the test program of the host computerand complete function of the lower computer controlling, test mode selection, testdata showing and database management.(3) Develop condition monitoring system of Chain-type Tool Changer. Install awireless vibration sensor to monitor the tool-stuck failure of Tool Changer andconduct experimental analysis. Use Empirical Mode Decomposition to takede-noising preprocessing for the original vibration signal. Then use Short-timeFourier Transform (Hamming window function) to analysis time-frequencycharacteristics of the vibration signal. Draw energy spectrum pictures of empty andfull tools of Tool Changer. And extract signal characteristics. Recognize the statecondition of tool-stuck.In this paper, the reliability test and condition monitoring system provides testcondition for the study of the reliability of Chain-type Tool Changer, and havesignificance of engineering practice.