Modal Analysis And Optimization Design Of Hydrostatic Spindle For High Precision Small Modulus Gear Slotting Machine

With the development of industrial robot,precision reducer,as the core component of robot,is mainly driven by small modulus gear.However,the machining accuracy of domestic gear shaper can not meet the requirements of robot machining with small module gear.Therefore,gear processing industry is in urgent need of a high-precision gear-shaper machine designed for the characteristics of small module machining.As the core component of high precision small module gear slotting machine,the main factors affecting machining accuracy are the structural characteristics,bearing capacity and static and dynamic characteristics of NC hydrostatic spindle.In this paper,the structure design and check,statics analysis,modal analysis and structural optimization design of the hydrostatic spindle of NC gear shaper are carried out to improve the machining accuracy of the small module gear slotting machine.The rational structure design of the main body structure of the static pressure spindle and the static pressure support is carried out.And check the bearing capacity of static bearing and static pressing spline,the maximum deformation of the spindle is obtained by static analysis of the maximum cutting force of the spindle,and the results show that the shape variable can meet the requirement of machining accuracy.The first six modal parameters of the spindle are obtained by the modal simulation of the spindle with ANSYS workbench finite element software.The results show that the maximum rotational speed of the spindle is lower than the critical speed,and the dynamic index meets the design requirements.Through the modal simulation analysis of the spindle bearing system,it can be seen that the support stiffness of the hydrostatic bearing has little effect on the natural frequency of the spindle,and the variation law of the natural frequency is the same with the increase of the modal order.Through the calculation of the unbalance of crank and slider mechanism,the structural optimization design of the spindle system is carried out.Firstly,the mechanical structure of the spindle system is analyzed,and the motion parameters of the structure are solved,and the mathematical model of the unbalance quantity is established through the motion parameters.Then the MATLAB is used to solve the imbalance,and the unbalanced maximum value of the whole mechanism in two directions on the crank is obtained.Finally,the design of the optimization device is carried out through the result of the solution.The test modal analysis of the static pressure spindle by hammering method shows that the simulation results are not different from the test results,and the natural frequency of the spindle measured in the free state will be lower than that of the simulation results.The vibration of the spindle was tested at 500str/min to 1000str/min,the acceleration sensor was installed on the tool holder side and the crank side,and thevibration data in X direction of the machine tool were collected,then the signal was de-noised by using the MATLAB wavelet toolbox,and the accurate vibration signal was obtained.The frequency spectrum is analyzed and the vibration parameters are calculated.The results show that the dynamic balancing device designed in this paper is used for gear shaper.The effect of vibration optimization is obvious,the optimization rate is 6.2%~11.4%.