Research On Structural Design Of High-Thrust Density Cylindrical Voice Coil Motor

The aim of this paper is to design high-thrust density,low-thrust fluctuation voice coil motor that used to numerical control punching machine.The commonly used numerical control punch press on the market is a pneumatic or rotary motor with crank mechanism,this paper proposes that voice coil motor is used as the linear impact part of the numerical control punch press.As a kind of liner motor,voice coil motor(VCM)can directly perform a linear motion,without intermediate switching mechanism.The cylindrical voice coil motor is characterized by structure,high utilization of permanent magnetic materials and coils,convenient control reversing,and has the advantages of fast response speed,no cogging effect.The linear impact system of numerical control punching machine generally requires high-acceleration,high-speed and high-frequency reciprocating motion.Therefore,the cylindrical voice coil motor is suitable for the linear impact system of numerical control punch,combining with the advantages of structure and control of the cylindrical voice coil motor.However,the low thrust density of the cylindrical voice coil motor is an urgent problem.Therefore,it is of great significance to make full use of its permanent magnetic materials,perform reasonable structural design,and increase the thrust without increasing the volume as much as possible.This paper studied the cylindrical voice coil motor used in the linear impact system of numerical control punch press.The main tasks include:Firstly,the basic electromagnetic theory of magnetic field and VCM’s working principle and classification were introduced.A mathematical model of VCM was established,and its voltage equation,back electromotive force equation and motor force balance equation were deduced.Secondly,according to the requirements of the linear impact system of numerical control punch press,the design index of the cylindrical voice coil motor is proposed.According to the characteristics of different type of voice coil motor and the design index of the motor,the type of the motor was selected.Then the primary and secondary materials of the motor were selected,and the primary and secondary structural parameters were calculated.The structure parameters of the cylindrical voice coil motor were optimized by finite element software.Finally,the paper introduced the theoretical basis of optimization design of voice coil motor.In order to improve the thrust density of a cylindrical voice coil motor,a novel winding-forward structure was proposed and the forward offset was optimized.The winding-forward structure type of Halbach was proposed,and it was optimized to further improve the thrust density of the motor.Based on the optimization results,experimental prototypes were made,and static thrust test was carried out on the prototype.The experimental results and the finite element results were mutually verified.The experimental results were consistent with the theoretical analysis and finite element results,and the prototype meets the design requirements of the numerical control impact system.