| Optical lenses,large reflectors,precision bearings,bionic bones,turbine blades,semiconductor devices and other key components affect national life,national defense and the development of science and technology.The key to improve the manufacturing capability of core components is to improve the capability of technology and equipment.Advanced machining technology represented by ultrasonic technology and magnetorheological technology is integrated with many disciplines to improve the surface precision and machining efficiency of parts to a certain extent.Ultrasonic machining technology has the characteristics of high frequency impact and intermittent cutting,which can not only improve the surface quality of the workpiece,but also change the stress distribution and reduce the heat generation.Ultrasonic vibration machining is often used in rigid contact machining.It is difficult to solve the coupling problem of force position in deterministic polishing.So this article focuses on the flexible control scheme,the ultrasonic vibration assisted the feasibility of spinning processing technology,design and manufacture a set of flexible ultrasonic vibration machining device,implement the perpendicular to the face of ultrasonic vibration assisted spinning processing functions,development control procedures,respectively from the aspects of theory and experiment research and prove the feasibility of scheme and device reliability.(1)The structure of the tool system is designed,and the manufacturing and calibration work is completed: the flexibility coefficient matrix equation of flexure hinges with different typical conic notches is established by using Euler Bernoulli beam theory of small deformation.The structural reliability of the device was verified by the strength check and modal analysis of the structural parts of the device using the knowledge of elastic mechanics,plastic mechanics and fracture mechanics and finite element calculation method.The vibration output sizes of different flexure hinges under different ultrasonic power output were calibrated through experimental tests.The electrical circuit of the pneumatic system was built,the output precision of the key components was calibrated,and the output compensation constant of the sensor was obtained.(2)Completed the tool system control program construction work: the channel between control system and upper computer was established through the RTW platform in Matlab/Simulink,and the pneumatic system model was identified by the M sequence input signals with a certain pulse shift period and amplitude,and the expression of the second-order transfer function of the pneumatic system was obtained.Genetic algorithm was used to optimize the PID controller,and a user program was written to optimize the controller parameters for the second-order system to simplify the parameter setting process.An adaptive controller with the function of automatic parameter correction is built,which can adjust the parameters in real time to adapt to different working conditions.Finally,the output performance of different controllers is compared and tested under different input signals.(3)Material removal model and three-dimensional finite element simulation model were established.Geometric models of single abrasive particle removal under ultrasonic vibration and traditional machining were derived,and the difference between material removal amount under ultrasonic vibration and traditional machining was analyzed.The finite element model of abrasive cutting of aluminum alloy workpiece was established by using finite element numerical calculation software.The single factor test method was used to simulate the cutting force,material removal amount,stress and temperature variation of traditional machining and ultrasonic vibration under different process parameters.Based on Preston equation,the ideal removal function of cylindrical polishing head with and without axial vibration is analyzed.(4)The tool system was used to complete the experimental study of multi-group removal:The stability and reliability of the tool system were verified,and the differences between traditional and ultrasonic vibration machining methods were analyzed.The tool system was used to reduce the surface roughness of the aluminum alloy workpiece to less than 10 nm.The low speed scratching experiment of single abrasive particle was carried out.The difference between the ultrasonic vibration assisted scratching and the traditional scratching was analyzed from the mechanical behavior,chip flow and removal depth.The material removal of ultrasonic vibration grinding and traditional grinding under certain pressure and the influence of process parameters on the material removal were analyzed by single factor experiment.The grinding and polishing experiments of aluminum alloy workpiece with red corundum and wool tool heads were carried out by orthogonal test method.The influence of ultrasonic vibration on the surface quality of workpiece processed by different tool heads was analyzed by Taguchi analysis method. |
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