Study on improving the precision of form surface produced in elastic deformation molding process

Elastic deformation machining method is a simple machining method in manufacturing aspheric surfaces process. In this method, the top surface of workpieces will deform and be in contact with the mold surface once vacuum is applied, while the bottom of workpiece is polished to flatness with the vacuum pressure is maintained stability. The machining process is finished when the thickness of workpiece is polished to size as required. When the vacuum is turned off and the workpiece is released from the mold, the bottom surface of the workpiece will be shaped into the aspheric surface as the top surface returns to its original flat surface form due to material elasticity. During machining, the form accuracy of aspheric surface is dependent on the value of vacuum pressure and contact between workpiece and mold surface. Therefore, the study of behavior of the glass in contact with the mold surface is necessary to determine the suitable mold surface. In this paper, the simulation results of the glass in contact with the mold in the different pressure values have been carried out. Based on the simulation and experiment results, the appropriate pressure values and mold surface are established for machining process by elastic deformation machining method. In order to improve the precision of form surface produced in elastic deformation machining, the mold profile is modified by selecting the finite element analysis results of workpiece in the case of vacuum pressure P = −95 kPa and the conic constant K = −3.