Reliability Research Of Bevel Gear Machine Tool Based On Vibration Characteristics And Quality Characteristics

Heavy-duty CNC machine tools are mainly used for the processing of large-scale high-precision parts and components,and are the master check-in equipment for national key enterprises such as national defense,military industry and aerospace.In the field of gear processing,the spiral bevel gear milling machine is the key equipment for processing spiral bevel gears.Its accuracy directly affects the processing accuracy of the spiral bevel gear tooth surface,and further affects the accuracy and stability of the gear transmission.However,due to the complex structure and processing principle of the spiral bevel gear milling machine,and the many couplings of the kinematic relationship,it has always been a difficult point to determine the mapping relationship between the accuracy of the machine tool and the machining accuracy of the tooth surface.It is difficult to accurately judge the milling of spiral bevel gears.Changes in the state and performance of the gear machine during service.This subject originated from the Chongqing Municipal Science and Technology Commission "Development and Application of Efficiency Technology for Numerical Control Machine Tools for Processing Key Components of Automotive Power Systems"(No.cstc2017zdcy-zdzx X0005).In view of the above problems,the spiral bevel gear milling machine of Tianjin No.1 Machinery Co.,Ltd.was selected as the research object.Due to the long life cycle of the spiral bevel gear milling machine,the traditional reliability evaluation method based on failure data cannot reflect the real-time reliability of the machine tool.Based on state monitoring,signal processing,and feature extraction,it collects the meshing processing vibration signals of the key parts of the machine tool in different states and the accuracy test report of the product,and then conducts the reliability analysis of the machine tool in different states,which is the state of the machine tool.Real-time performance monitoring and maintenance provide certain theoretical support,which has certain reference significance for the reliability evaluation of the whole machine.The specific research contents are as follows:(1)Taking the spiral bevel gear machine tool as the research object,due to its complex structure,many sources of excitation,and the coupling of the mutual motion relationship between each moving part,it brings many difficulties to the reliability evaluation of the machine tool.Based on the basic structure,main motion parameters and working principle of the cutter head part of the spiral bevel gear machine tool,this paper analyzes the vibration mechanism of the machining process,and conducts a theoretical summary of the current commonly used machine tool vibration signal analysis methods and reliability evaluation methods and analysis.(2)In view of the obvious non-linear and non-stationary characteristics of the vibration signal of the spiral bevel gear machine tool,the machine tool vibration signal acquisition platform was built using Labview and NI acquisition system to complete the collection of test data.The signal analysis method of stationarity signal completes the extraction of multiple indicators of the signal,and then uses the distance evaluation technology to screen them,and selects the root mean square value and the PF2 energy value as the state-sensitive feature indicators.(3)Based on the two characteristic indexes screened out by the vibration signal of the machine tool under different conditions,based on the reliability analysis method,the vibration signal characteristic index and the reliability index of the machine tool reflecting the operating state of the machine tool are established through the Weibull proportional failure rate model.Contact,and then obtain the Weibull proportional reliability function based on state characteristics.Finally,the maximum likelihood estimation is used to estimate the reliability parameters of the parameters in the model,and the reliability calculation of the different operating states of the machine tool is completed.(4)After the process of collecting and testing the vibration signals of different states of the machine tool,through the gear measuring center,the processed gear parts are detected to obtain the detection accuracy data,and the machine tool processing error distribution behavior sequence is constructed,and the gray relational analysis method is used to analyze the gears.The machining quality of the parts is evaluated,and then by calculating the absolute correlation degree of each machining error distribution behavior sequence,the reliability of the consistency,retention and repeatability of the machining error of the machine tool is evaluated.