자기연마 가공에서 초음파 진동을 이용한 표면거칠기 향상

Abstract

Recently, the demand of precision parts has increased due to the industrial development and moreover, the industry required precision finishing on hard material. Magnetic abrasive polishing (MAP) is one of the most promising finishing methods applying to complex surfaces. MAP process is a nontraditional method for polishing the surface of workpiece by the tool having flexibility. In this process, the working gap between workpiece and inductor is filled with abrasive mixture, which is well known as magnetic abrasive particles. These particles are able to remove a very small amount of materials from a workpiece. In this context, this process has a low efficiency when applied to very hardened materials and it is, therefore, necessary to improve the efficiency of this process. In this study, an US-MAP hybrid process using ultrasonic vibration by piezo electric actuator was developed. To evaluate the synergy effect between ultrasonic and magnetic abrasive polishing (US-MAP) process, an experiment was performed in each experimental condition. The experimental parameters were selected as frequency, amplitude, magnetic flux density, spindle speed, working gap and feed rate. As a result, vibration frequency at 28kHz was suitable for the US-MAP hybrid process. When amplitude was 11 and 34㎛, it was confirmed that surface roughness was improved compared to that of 55㎛. Surface roughness after the US-MAP hybrid process showed a tendency to be improved with the increase of spindle speed, magnetic flux density and selection of suitable amplitude. And, when a working gap was 1mm, the superior surface roughness was examined. Also the 60mT of magnetic flux density, 34㎛ of amplitude, 800rpm of spindle speed and 20mm/min of feed rate provided an optimum result in US-MAP hybrid process.