Finishing of mold corner by ultrasonic-vibration planing method

To process the cavity for forming plastic molds, a machining center with a rotational tool, such as an end mill, is generally used. However, a deep pocket groove with a right-angled corner configuration is generally difficult to process by the above-mentioned processing method. In this study, to investigate the method of processing a deep pocket groove with a right-angled corner using a machining center, a finishing method was examined in which a corner R in a pocket groove which was processed by an end mill, was subjected to finishing by ultrasonic-vibration planing in the direction of the groove. To realize this process, a tool unit for ultrasonic-vibration planing, which incorporates a planing tool for longitudinal vibration, was proposed. Then, the basic cutting performance of the unit in planing a pocket groove was studied in comparison with the conventional bending mode ultrasonic vibration tool. Our study revealed that in general, the ultrasonic-vibration planing method considerably decreased the cutting resistance, improved the dimensional accuracy, and furthermore, reduced the roughness of the finished surface compared to the conventional planing method. Finally, an experiment on processing the right-angled corner of a deep pocket groove was carried out, the results of which clarified that proposed longitudinal ultrasonic-vibration planing enables the corner R of a deep pocket groove to be processed at a right angle, which has been impossible or at least unpractical using the conventional bending mode ultrasonic-vibration tool.