Developing Of Ultrasonic Abrasive Device For WC Optical Mold And Processing Properties Study

In recent years, compression molding has become an important method for lens mold processing. How to process the nano-surface roughness and high shape precision lens mold has become a subject which the scholars extensive researched. Abrasive and polishing is an important method to improve the forming accuracy. At present, the commonly abrasive methods for lens mold are MRF and magnetic jetting, which can reduce the workpiece's surface roughness, but hardly improve its shape precision. So there is an urgent to develop a new type of advanced abrasive method with high efficient and high quality.Ultrasonic abrasive technology is a non-traditional processing technology. Compared with traditional abrasive techniques, ultrasonic abrasive is high efficiency, and has small cutting force when abrading, and could achieve high surface quality after abrading. Especially, when abrade hard and brittle materials, ultrasonic abrasive could easily realize ductility removing. Therefore the processing surface is hardly ruptured, and high shape precision and low surface roughness is achieved. In this research, ultrasonic abrasive technology was applied to grind lens mold, being hoped to achieve high-precision aspheric lens mold by deterministic ground.This project is from the Key Project of State Supporting Program for Science and Technology (ultra-precision polishing equipment and technology for vehicle optical lens and its mold). In view of the current challenges in abrading lens mold, the researching was carried out as follows:(1) To meet the requirements of high precision and efficient in lens mold processing, ultrasonic elliptical vibration abrasive technology was proposed, so that lens mold could be ground in three-axis linkage machine tools though ultrasonic vibration abrasive.(2) The previous elliptical vibration transducer is a three incentive structure. It is not only difficult to design and costly to produce, but also high energy consumption and large heat. In this paper, a single-excitation ultrasonic elliptical vibration system was designed. The vibration characteristics of acoustic system were clarified on the base of Finite Element Analyses (FEA). The system's natural frequencies within the adjustable scope of generator and corresponding vibration modes were obtained. The results provide a powerful guarantee for the studies in ultrasonic elliptical vibration abrasive mechanism and related experiment.(3) A set of ultrasonic elliptical vibration abrasive device was produced. By applying the devices, K9 glass abrasive experiments were carried. The abrasive factors in this method such as workpiece rotation speed, abrasive particle size, abrasive force in this abrasive method which affecting the efficiency of abrasive and the roughness of abraded surface were Analyzed. And the experiment of ultrasonic vibration abrasive for tungsten carbide aspheric workpiece was carried. By comparing the results of ultrasonic vibration abrasive and non-ultrasonic vibration abrasive, the effectiveness of the ultrasonic abrasive method is proved. Additional, in view of the uneven surface quality after abrading, ultrasonic varying speed abrasive was proposed. The Experimental results show that the method has good effect.The study results would contribute to reveal the mechanism of the high precision abrasive in tungsten carbide and develop new technologies for non-spherical optical mold abrasive, and further promote the promotion and applications of aspheric optical components.