| Spiral bevel gears are generally processed by milling or hard tooth surface grinding.When grinding the hard tooth surface,the grinding force is large and the temperature is high,and the gear surface is prone to thermal damage,which reduces the service life of the gear;Based on the above problems,scholars at home and abroad began to study the methods to improve the traditional grinding,in which the ultrasonic vibration assisted grinding is a machining method that can effectively improve the above problems,and its main core is the ultrasonic gear grinding device.In this paper,the ultrasonic gear grinding device is studied as follows:1.Design of ultrasonic machining system: The design of ultrasonic machining device mainly focuses on the design of horn.Taking the ordinary stepped horn as an example,a longitudinal resonant horn structure is designed by using the non resonant design theory,and its simulation analysis is carried out;The design frequency is28000 hz,the modal longitudinal vibration frequency of the horn is 28.10 khz,and the error is 0.36% compared with the theoretical value of 28 k Hz,which verifies the feasibility of this design.2.In order to join the ultrasonic machining vibration system to transform the machine tool,combined with the existing original conditions,an ultrasonic gear grinding device for spiral bevel gear with hollow cylindrical large tool head is designed;Based on the longitudinal vibration dynamic equation,combined with the boundary conditions of each region,the integral design and split design are carried out;The longitudinal vibration frequencies of the two models are reasonable,but the size and vibration characteristics of the two models are different;Only changing the connection mode for analysis,it is found that the connection mode will lead to the change of the model mode.Further analysis shows that the preload at the connection is the main reason for the change of the vibration characteristics of the model.3.Based on Mindlin plate theory,an ultrasonic longitudinal bending coupling resonant horn with large tool head is designed.The grinding wheel tool head mainly uses pitch circle vibration.Firstly,the grinding wheel model with the blade bottom height of 9mm is obtained through simulation analysis.Its modal frequency is 20045 hz,and the error with the theoretical design frequency is only 0.22%,which meets the design requirements.The vibration model of longitudinal bending resonant horn is established.The horn needs to meet the ultrasonic longitudinal bending coupling resonance conditions and boundary conditions.The unknown size parameters of the horn are obtained by calculation.The model of ultrasonic longitudinal bending resonant coupling horn is established,and its simulation modal analysis is carried out.The modal frequency is 19309 hz,and the error with the theoretical design frequency of20000 hz is 3.45%.The luffing rod vibrates axially,and the large tool head bends and vibrates based on the center of the circle,and the vibration type is pitch circle,which meets the design requirements. |
