Optimum Design Of Vibration And Noise Of The Electric Angle Grinder

Vibration and noise are important characteristic parameters of power tools,and also an important factor affecting the mental and physical health of operators.Therefore,vibration and noise reduction are an indispensable research object in the power tool industry.In this paper,a certain angle grinder is taken as the research object.The vibration signal spectrum is analyzed experimentally to find the main excitation source of vibration.By optimizing the rotor design and dynamic balance,the vibration value of the whole machine is improved,and the rotor natural frequency is quickly calculated based on the Rayleigh method.form.Through the modal analysis method,the noise source is analyzed,and the design of the stator and the fan is optimized,which reduces the whistling sound and the total sound pressure level of the whole machine,achieves the purpose of noise reduction,and improves the performance of the product.(1)According to the relevant test standards,the angular vibration noise was tested and evaluated;the vibration level of the original design was evaluated by the vibration test;the vibration signal spectrum was analyzed,and the first-order natural frequency of the rotor was 320Hz and the machine resonance frequency was 325Hz.It is inferred that the machine resonance caused by the rotor.(2)Simulate in Hypermesh to get the modal parameters and compared with the test results,find out the CAE simulation results are not precise.Establish the rigid body dynamics model of the angle grinder system,establish the system vibration differential equation according to the Lagrange equation,program the rotor natural frequency expression in Excel,and verify the accuracy of the program by sweep test.A rapid design method of rotor natural frequency is provided,a new rotor is designed according to the optimized parameters,and the feasibility of the new design is verified by the frequency sweep test.It is effective by increasing the rotor shaft diameter and changing the connection stiffness between the lamination and the rotor shaft.Increase the natural frequency of the rotor and avoid the resonance point.(3)The relationship between the balance of the angle grinder rotor and the vibration was studied.The equilibrium quality level limit table and the dynamic balance were converted into a static couple balance table by Excel.The static balance limit of the angle grinder rotor was defined according to the table.The accuracy of the definition of the equilibrium limit was verified by further vibration tests and the vibration of the whole machine was completely reduced to below the vibration limit of 2.5 m/s2.(4)The modal test is performed on the angular grinding stator to further verify the noise source.After experimental data analysis,it is confirmed that the noise source is derived from the stator resonance and the fan rotation noise.By improving the stator structure and reducing the fan diameter,the total sound pressure level and the whistling sound of the machine are greatly reduced.By optimizing the design of the motor rotor to avoid the resonance point of the whole machine,combined with the optimization of the dynamic balance,the purpose of reducing the vibration of the whole machine can be achieved.The optimization of motor noise adjusts the natural frequency of the stator under electromagnetic excitation to avoid the whistling sound caused by resonance,and reduces the rotational noise of the fan through the optimized design of the fan,thereby achieving the purpose of vibration reduction and noise reduction.At the same time,for the calculation of rotor natural frequency and dynamic balance,it is proposed that Excel can be used to calculate the table aid design by fast calculation formula method,which can quickly optimize the rotor design scheme or find the root cause of the balance problem,and achieve the purpose of quickly optimizing the vibration noise problem.