| Micro-EDM has unique advantages in machining micro array holes because of nomacro forces in processing, non-contact discharge between the tool and workpiece andmicro single discharge energy. But in general it should take a long time to fabricate themicro electrode tool on line which is used in micro-EDM, in addition, the electrode toolwear in processing, especially in micro-EDM milling. These two drawbacks greatlyaffect the processing efficiency and accuracy in machining micro array holes. Therefore,the development of the high turning speed and precision spindle which can directlyclamp commercially available micro electrode wire of different diameters andautomatically compensate the tool wear is of great significance in reducing microelectrode tool preparation time and improving the processing efficiency of themicrostructure.The advantages and disadvantages of domestic and international micro-EDMspindle device have been analyzed on perspectives of the range of electrode wirediameter that can be clamped, rotational accuracy, response frequency and the automaticcompensation of the tool wear. Then a program of peristaltic spindle that combined withthe precision2D aligning device has been proposed. In this program the micro electrodetool is clamped by a micro V-groove structure, the coaxial accuracy of the electrodewire and spindle is adjusted through the2D aligning device and the clamping,releaseing and feeding of the electrode wire is conducted by the voice coil motor.For the clamping of electrode wire is among100~300μm, the micro V-groove isdesigned after the analysis on influence of the dimension of micro V-groove to thelocating of different diameter electrode wire. Several programs of processing micro V-groove have been analyzed and compared to solve the problem of small size and highmachining accuracy. The micro V-groove clamping mechanism has been designed withtheoretical and finite element analysis, through the analysis, the force required inclamping the electrode wire is calculated as9.9N. The conditions of deformation andstrength are verified and it can meet the requirements.To optimize the design of the precision2D aligning device, the parametricmodeling has been established by ANSYS. Through the analysis of the effect of angularvelocity and angular acceleration of the spindle on the device it is found that thedeformation of the device with the angular velocity of2000r/min and angularacceleration of1500rad/s2is within0.3μm. Through analysis of the modal, it is got thatthe first-order to the third-order natural frequency of the device are742.9Hz,951.67Hz,2277.9Hz and they can meet the requirements of the dynamic response capability. Afterthe analysis on the interaction of the deformation of the aligning device in X and Y directions, it is obtained that when the adjustment in X direction is82.51μm, thedeformation in Y direction is7.26μm and when the adjustment in Y direction is101.7μm,the deformation in X direction can be neglected.The poly-magnetic and radial magnetizing voice coil motor have been analyzedand designed with the indicators such as the height, diameter, magnetic flux density inair-gap, force constant BL and permanent magnet volume of the voice coil motor. Thenthe poly-magnetic voice coil motor has more uniform air-gap magnetic field and morestable output force, and has been selected as the final plan. After machining of theoptimized voice coil motor, the maximum output force for21.96N is measured,and meetthe requirements. The maximum variation of the output force in the3mm range is1N... |
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