Research On Design Method And Vibration Characteristics Of Permanent Magnet Synchronous Motorized Spindle

The motorized spindle is one of the major components of high-performance CNC machine tool systems.However,high-performance motorized spindles configured in high-speed,high-precision CNC machine tools and machining centers produced independently by China are mainly dependent on imports.The key components and complete machine of domestically produced motorized spindles in China are relatively weak in system design,manufacturing,testing,and inspection technology,which seriously restricts the technological development of domestically produced motorized spindles.Therefore,it is urgent to further improve the design theory and key technology system,comprehensively enhance the design and manufacturing capabilities of motorized spindles,overcome the localization difficulties of key supporting components,form a complete system of digital design,manufacturing,inspection,assembly,and testing of high-performance motorized spindles,and comprehensively improve the industrialization level of domestic high-performance motorized spindles.It is extremely important to accelerate the transformation and modernization of China’s manufacturing industry and promote high-quality economic development.Permanent magnet synchronous motorized spindle has become an important research direction in recent years due to its high power density,high efficiency,high power factor,good dynamic performance,and the ability to simultaneously achieve low-speed powerful cutting and high-speed precision cutting.With the increasing demand for the performance of motorized spindle in high-speed and high-precision machining,there is still some weakness in the design methods and theoretical research of high-speed permanent magnet synchronous motorized spindle systems.Therefore,this article conducts research on the design methods and vibration characteristics of high-speed motorized spindles.Based on the sub domain analytical calculation method,a precise solution method for radial and tangential magnetic flux density was studied for the no-load magnetic field,stator winding magnetic field,and load magnetic field of surface mounted permanent magnet synchronous motorized spindle.The calculation results were validated using finite element numerical methods.A study was conducted on the characteristics of electromagnetic force and electromagnetic force waves,revealing the regularity of the number,frequency,and amplitude of radial electromagnetic force waves at the air gap of surface mounted permanent magnet synchronous motorized spindle.At the same time,the vibration characteristics of the stator structure were studied,and the influence of the key structural dimensions on the vibration of the stator core was obtained.On the basis of completing the overall structural design of the motorized spindle,the basic size equation and key parameters of the motorized spindle drive motor were analyzed to determine their impact on the electrical performance of the motorized spindle.At the same time,a parameterized electromagnetic design was carried out on the performance of the motorized spindle using a combination of field and circuit methods,and finite element analysis and verification were conducted.Based on the structural characteristics of high-speed permanent magnet synchronous motorized spindle,a study was conducted on the optimization method of the main pole magnetic field waveform,and a magnetic resistance modulation main pole magnetic field waveform optimization method that is more suitable for high-speed rotation was proposed.This method can effectively suppress and weaken electromagnetic force harmonics and torque ripple.Multiple schemes were compared and analyzed based on the amplitude of the fundamental wave and the total harmonic distortion rate of the air gap magnetic density.The methods of restraining tooth harmonic and torque ripple were studied,and the high-precision manufacturing and assembly methods and permanent magnet protection methods were explored according to the structural characteristics of the reluctance modulated permanent magnetic spindle rotor.Finally,the stiffness and strength analysis and validation of the rotor were conducted using the finite element method.The influence of the main structural parameters of the motorized spindle on its stiffness characteristics was analyzed,and the optimal range of the motorized spindle span was obtained.The motorized spindle model was appropriately simplified and equivalent using finite element software,and the stiffness of the motorized spindle was calculated.The results of the calculation of the stiffness of the motorized spindle were obtained.The actual stiffness testing of the motorized spindle was carried out on the static stiffness testing platform of the permanent magnet synchronous motorized spindle,and the test results were consistent with the finite element simulation results.The theoretical analysis and calculation results of the stiffness characteristics of the electric spindle have been effectively verified.The concentrated mass model was used to simplify and discretize the motorized spindle rotor,and the equivalent method of bearing support stiffness that affects the dynamic characteristics of the rotor was studied.A transfer matrix with a time factor was established to solve the effect of gyroscopic torque on rotor dynamic characteristics.The dual step QR algorithm was used to solve the critical speed and response of the electromechanical coupled anisotropic supported permanent magnet synchronous spindle rotor.Effectively prevent effective root loss and root overflow during the cleanvalues resolution process.The influence of rotor dynamics,static eccentricity,and magnetic tension on the critical speed and response of the rotor was also determined.The thermal deformation mechanism of permanent magnet synchronous motorized spindle was investigated,and its main heat source was explored,and thermal load analysis and calculation were conducted.At the same time,a comprehensive analysis was conducted on the impact of the cooling system,oil and air lubrication system,and central cooling system of the motorized spindle on heat dissipation,and thermal management methods were studied.The influence of the cooling water flow rate in the cooling system and the compressed air flow rate in the oil air lubrication system on the heat transfer coefficients of the motorized spindle was obtained.By reasonably changing the cooling water flow rate and conducting transient temperature field simulation analysis,the temperature rise of various components of the motorized spindle was effectively reduced.The central ventilation cooling method has been adopted,which can effectively improve the rotor and spindle heat dissipation capacity of the motorized spindle.A thermal characteristics test bench for motorized spindle was built,and vibration data at various speeds were collected and processed.The experimental data was analyzed,and the thermal vibration characteristics of motorized spindle were summarized.At the same time,combined with the experimental data in the thermal equilibration at different speeds,the front and rear bearing amplitudes of the motorized spindle were statistically analyzed,and the influence of the bearing stiffness and clearance changes caused by thermal deformation on the amplitude was summarized.