Papers by Author: Bing Hai Lv

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.

Abstract: The lapping trace distribution on ball surface is one of the key factors during the lapping process, which can affect the sphericity of lapping. The Rotated Dual-Plates lapping mode (RDP lapping mode) can achieve better uniformity of lapping trace distribution on precision ball surface, which ensure the results of forming sphere by lapping. Combining with the basic principle of RDP lapping mode, as well as the analysis of the kinematics of the RDP lapping method, this paper puts forward a basic rule about the material removal at the contact point between the ball and the plate with the material removal rate equation of bearing steel, and the improvement of the sphericity which can be simulated, and is defined as the lapping uniformity according to basic rule equation. The influence caused by the lapping pressure and the speed of the plates are considered in the simulation, the surface of ball is triangle grid divided. The uniformity of lapping is evaluated at different speed ratio, and eventually a better curve of the speed ratio can be got, so the lapping uniformity during the RDP lapping mode can finally be accurately evaluated.

Abstract: This paper firstly summarizes two-dimensional numerical simulation of semi-fixed abrasive tool (SFAT), then three-dimensional model of SFAT is established by PFC3D (Particle Flow Code in 3 Dimensions). In order to make the compression ratio simulation match to experimental one about SFAT, the mechanical parameters of model are adjusted. In the direct shearing simulation, the relation between the shear stress and the horizontal shear displacement under different parallel bond stiffness are obtained. By Comparative Analysis the numerical results and test experiments of the direct shearing, the three-dimensional model of SFAT is further proven rational.

Abstract: Spin angle is an important target of expressing ball rotation in the lapping process. Whether lapping track can uniformly cover the ball surface or not is directly determined by the variation of the angle. The simulation of spin angle track of the ball based on ADAMS (Automatic Dynamic Analysis of Mechanical Systems) with Dual Rotation Plates Lapping Method by applying virtual prototype technology and using ADAMS is given by the article. The track based on ADAMS is similar with the track of using mathematical theory on the whole. The simulation results show that DRP lapping method owns better lapping uniformity and it is easy to apply to science for the simplicity of structure and control. The spherical lapping uniformity will be further studied with ADAMS in a convenient way.

Abstract: To improve the sphericity and processing uniformity of precision ball, Simulations and analysis of the mechanism Position Deviation of Rotated Dual-Plates Lapping on precise Sphere, it can be indicated that mechanism Position Deviation (down plate axial deviation and down plate radial deviation) have little disadvantageous influence on sphericity and processing uniformity.

Abstract: As the consumer market in the optics, electronics and aerospace industries grows, the demand of ultra-precision aspheric surface increases. The shape accuracy of the optical lens changes significantly with deformation conditions and optical properties of the lens varies with stress distribution within the lens. Therefore, determining the deflection and stress of glass lens is very important to improve the quality of the lens. In this paper, the deflection and stress theoretical results of BK7 glass plate have been presented in different cases of elastic deformation processing. The results are compared with the finite element analysis (FEA) to demonstrate the robustness and accuracy of algorithm in calculation of stress and deflection. The mentioned finite element models were established using the software Abaqus/CAE. The analytical and FEA results showed that if the edge of plate is simply supported, the maximum deflection is 4 times larger than in the fixed edge case. Otherwise if the edge and centre point of plate is simply supported, the maximum deflection is 2.5 times lower than in the fixed edge case and 11.3 times lower than in the simply supported at edge case.

Abstract: In order to obtain low surface damage and high machining efficiency for advanced ceramics, overcome clogging and dressing difficulties of traditional metal bonded super-hard abrasive, a novel fine super-hard abrasive with porous self-generating ability is proposed in this paper. And the matching of filler and dissolvent in abrasive are studied. Soluble filler is a key technology of porous self-generating fine super-hard abrasive. In this paper, metal, metal oxide and non-metallic oxide are respectively used as soluble fillers. Results of the experimental shows: In metal bonded super-hard abrasive, metal, metal oxide and non-metallic oxide as soluble filler are feasible, correspondingly, FeCl3 solution, aqueous solution and weak alkaline solution are used as dressing dissolvent, respectively. It can be met the requirement of high precision machining for advanced ceramic materials, hard and brittle machining materials.

Abstract: To improve the machining efficiency as well as surface roughness, a series of experiments employed fixed abrasive tools are carried out for stainless steel substrate, and influences of properties of fixed abrasive tool on the lapping process are studied. It is found that the resin is the best bonding material in this study. The surface roughness under different concentration of bonding material is similar, and the material removal rate (MRR) increases as the concentration of bonding material decreases from 50% to 20%. But too little of bonding material results into low bond strength that causing low material removal rate. It is also found that higher shear strength, lower wear rate, and the shear strength of the tool with 35% bonding material is the highest. It is obvious that the surface roughness and material removal rate decline as the grit size decreases. The roughness of surface lapped with resin bonded 4000# SiC abrasive tool comes to 18nm, and the material removal rate is 0.63μm/min.