Vibration Optimization Of Hob Spindle System On Direct-drive Gear Hobbing Machine

“Zero-transmission” also known as Direct-drive, namely the executioncomponent(such as the spindle rotation, the table linear feed or the low-speed rotation ofthe rotary table) of the machine directly drived by the motor, cancels all mechanicaltransmission links and makes the length of main drive zero. It not only can increase themachining precision and speed of the machine in a large scale, but also can morethoroughly solve the attrition and larger moment of inertia problems which exist in themechanical transmission links, which enhances the precision retentivity and the movementsensitive of the machine, in addition, simplifies the mechanical structure effectively.Zero-transmission Technology application in machine enhances the cutting speed greatly,which put forward higher requirements. At the same time, Zero-transmission cancels thetransmission buffer and makes the cutting force act on the spindle and motor directly,which similarly makes the final execution component have better vibration resistance. Sodeeply making researches on and enhancing the static and dynamic characteristic of thespindle of Zero-transmission gear hobbing machine becomes the important work that mustdo in time.Based on Zero-transmission gear hobbing machine as research object, this papermainly includes the following research work:①On the basis of a brief description of gear machining technology, especially thegear hobbing processing status quo and development trends, this paper analyzes the“Zero-transmission” technology application status in detail; focuses on the structuralcharacteristics the domestic and foreign research situation of the static and dynamiccharacteristic of the electric spindle; analyzes and summarizes the problems China faces onthe static and dynamic characteristic, and puts forward the research objectives and maincontent.②On the basis of a brief description of the use, the transmission system and themain structure of YK3610Zero-transmission gear hobbing machine, this paper analyzesthe structure of the hob spindle system in detail, and according to the structuralcharacteristics of the system, puts forward the research requirements of the static anddynamic characteristic and the evaluation index of the dynamic characteristic.③This paper analyzes the principle, characteristics and applicability of the transfer matrix method systematically, and improves the conventional transfer matrix effectively, inaccordance with the research requirements. The natural frequency is calculated by usingthe improved transfer matrix, and the calculated results are compared with results obtainedby the modal analysis of finite element method. The results show that, the improvedtransfer matrix method is more suitable for the research; on the basis of the transfer matrixmethod, the application of MATLAB achieves the variable parameter analysis of thenatural frequency, vibration mode and dynamic stiffness of the spindle component, andanalyzes the laws and characteristics which the plurality of design parameters influence thestatic and dynamic characteristic, and provides the fundamental basis for the structuraloptimization of the system.④In accordance with the basic theory, nature and characteristic of the Orthogonalexperiment, this paper makes researches on the correlation and significance which eachimportant design parameters affects the dynamic stiffness of the system. Range analysis,variance analysis and correlation analysis results of the factors show that, the impact of theback-end bearing stiffness is the biggest for the amplitude, following the overhang, thefront bearing stiffness, the bearing span and the spindle inside diameter. Each factor for theeffect of the dynamic stiffness of the system is not obviously related. So components of theoverall structural optimization can be used the method which each design parameter getsthe optimal values within the design constraints. The method can greatly improved thevibration resistance under the premise of the system structure without significant changes.