Papers by Author: Zhe Wu

Abstract: Porous self-generation superabrasive tool (PSST) is a newly developed metal bonded superabrasive tool. It is found that processing parameters have great influence on the machining quality when using PSST. This paper focuses on the application of Taguchi method for optimization of lapping process parameters when using PSST to obtain the best surface quality. An optimization experiment for lapping optical glass with PSST was designed by Taguchi method. Surface roughness Ra is considered as criteria for optimization. Influence of parameters involving filler concentration in binder, lapping load, lapping speed and concentration of solute are discussed, and the optimum lapping condition is figured out. The optimization result illustrates that the experiment design based on Taguchi method can successfully applied to determine the optimum processing conditions for lapping process using PSST.

Abstract: Deformation behavior; Aspheric surface; Finite element method; Contact area Abstract. Elastic deformation machining is a novel processing method for aspheric surface. In the machining process, the workpiece will deform and be in contact with the molded surface once load is applied. In this paper, a finite element model was built with Abaqus/CAE package to predict the deformation behavior of glass plate and some significative conclusions were obtained. The numerical simulation results show that the contact area between the plate and the mold is increasing with different pressure. Once the required pressure value is determined exactly, the glass plate can be deform and completely contact with the mold. The deformed shape of glass plate will completely contact with the mold at pressure p=100kPa. These conclusions have the positive significance for the applying of elastic deformation machining.

Abstract: Elastic deformation machining is a new developing machining method for machining aspheric optical workpieces. Fracture property of glass plate under uniform pressure has important influence on the design of mould which is the key part of elastic deformation machining. In this study, to explore the fracture property of glass plate under uniform pressure, the deformation property of glass plate under uniform pressure is analyzed, a fracture experiment of glass plate using vacuum absorption is carried out on a self-developed “fracture testing system” and the values of critical vacuum degree is fit to Weibull distribution. Results show that fracture of glass plate under uniform pressure is comminuted, and for glass plate with depth of 1.95mm and diameter of 96mm, the relative safe value of maximum center offset of the mould’s profile is 0.5mm.

Abstract: The soluble filler in the newly developed metal bonded superabrasive tool named porous self-generation superabrasive tool (PSST) plays the most important role. To investigate the influence of filler material and its content on the mechanical properties, Zn, CaO, SiO₂ are employed as the soluble filler.Shear experiments and lapping experiments are carried out. It is found that the shear force of PSST with Zn is the highest, and declines little from 3.2 kN to 2.9kN with increase of filler content from 10wt% to 30wt%. On the contrary, the shear force of PSSTs with CaO and SiO₂ decline obviously from 2.1kN to 1.2kN, and 1.7kN to 0.6kN respectively. The wear rate of PSST depends on not only its own mechanical strength but also the dissolution rate of the filler. It comes out that the wear rate of PSST with Zn is similar to that of PSST with SiO₂, ranges from 0.04mm/h to 0.13mm/h. The wear rate of PSST with CaO is much lower, ranges from 0.02 mm/h to 0.08 mm/h.

Abstract: The dressing principle of a newly developed metal bonded superabrasive tool named porous self-generation superabrasive tool (PSST) is introduced. It is found that the ‘soluble’ filler added in the bond material can be dissolved by certain solution, and porous structure can be formed on the highly compacted surface layer of the metal-bonded superabrasive tool. The dressing process of PSST are investigated by a series of lapping experiments. Surface topography of PSST during lapping process is observed. It is found that the porous structure can be maintained on the PSST surface layer during the lapping process. There is little jam happened on the PSST surface. The generated porous binder on PSST surface layer is more susceptible to bond fracture, which is benefit to the self-sharpening of the metal bonded superabrasive tool.

Abstract: Plane lapping method using the elasticity of materials has many advantages comparing with current machining method for aspherical surface machining. Due to the deformation of the workpiece, the material removal characteristics of this method are different from the traditional lapping process of flat surface. In this paper, based on the Preston equation and plate theory, the theoretical model of the material remove rate is built in the case of proving experiment. Then the proving experiment of elastic deformation method is carried out, the recorded values fit well with theoretical ones, which shows that the theoretical model of material removal property is valid and the variation of MRR is related to the deformed profile of workpiece.

Abstract: The mechanics of elasticity is a novel aspheric fabrication technology that could transform aspheric optical fabrication technology into sphere optical fabrication technology. The shape accuracy of the optical lens changes significantly with deformation conditions and various parameters of machining process. Considering Polymethyl-methacrylate (acrylic PMMA) characteristic and elastic deformation aspheric surface generated by the load is uniformly distributed over the inner portion of the plate, the investigation of elastic deformation machining method for aspheric surface generation is introduced in this paper. The subject of this study is to determine finished surface shape of acrylic after lapping process. The experiment results are compared with the finite element analysis (FEA) and theoretical results. The mentioned finite element models were established using the software Abaqus/CAE. The experiment result showed that the error of deformation curves between analytical and experimental result is smaller than FEA and experimental result. The theoretical of deformation curves obtained close to the experiment curves. The results indicate that the experimental investigation of elastic deformation machining method can be used to fabricate the aspheric surface with simple machining process and high efficiency.