Papers by Author: Qiu Sheng Yan

Abstract: This paper establishes the simulation error data models of roundness error, spindle rotation error and noise signal from the characteristics of error signal based on three-point method. From the Matlab simulation, the influence of installation angle error of the sensor, roundness error magnitude and the noise on the segregation accuracy was studied in detail. This makes up the deficiencies of previous studies, and also provides a good foundation for further improving the accuracy of three-point method.

Abstract: To improve the effect of magnetorheological finishing (MRF), it is necessary to control the behavior of abrasive particle effectively in machining process. This article described the machining principle of semi-bond abrasives under the MR effect, then, analyzed the magnetic field of the polishing tool. Based on the magnetic field theory, the constrained model of abrasive particle was established, consequently, the force and the machining behavior of abrasive particle were analyzed. And an experiment was carried out to analyze the effect of the abrasive behavior on the material removal. The results show that the experimental results are identical with the theoretical analysis. Therefore, the control of the particle behavior in process is proved to be available.

Abstract: Based on the electro-magneto-rheological (EMR) effect, the Fe3O4-based EMR fluid dispersed with micron-sized finishing abrasives is used as a polishing fluid to form a dynamical tiny-grinding wheel under an electro-magnetically coupled field. Using this EMR-effect-based tiny-grinding wheel, experiments were conducted to investigate the effect of the grain size, content and material of abrasive on material removal effect of normal glass. Results indicate that the abrasive can change the chain-like structure of the EMR-effect-based tiny-grinding wheel and influence the material removal ability of the tiny-grinding wheel remarkably. The material removal amount increases with the increase of the content of diamond abrasive in the EMR fluid, and grows slowly when the proportion of diamond abrasive exceeds to 6%. While the grain size of abrasive increases, the material removal amount increases at the beginning and decreases afterwards. The effect of abrasive on material removal depends on the hardness of abrasive, the greater the abrasive hardness, the higher the material removal efficiency. The machined area has a close relationship with both the density and grain size of abrasive.

Abstract: A new planarization polishing method based on the cluster magnetorheological (MR) effect is presented to polish optical glass in this paper. Some process experiments were conducted to reveal the influence of the content of carbonyl iron and the abrasive materials in the MR fluid on the machining effect, and the machining characteristic of polished surface was studied. The results indicate that the surface roughness of the polished workpiece can be reduced rapidly when the strong magnetic field is applied, and ultra smooth surface with Ra 1.4 nm can be achieved while the CeO2 abrasives are used in the MR fluid. The content of carbonyl iron obviously influences the machining effect of this planarization polishing method based on cluster MR-effect. With the increase of the content of carbonyl iron in the MR fluid, the material removal rate improves and the surface roughness reduces rapidly. However, the difference of abrasive material results in various machining effects. As for the K9 optical glass, the CeO2 abrasive is better polishing abrasive than the SiC abrasive in the planarization polishing technique based on the cluster MR-effect.

Abstract: Aiming at micro machining of 3D microstructure of brittle materials with a novel tiny-grinding wheel based on the electro-magneto-rheological (EMR) effect, five conical tools with different cone angles are designed to reveal the effect of the cone angle on the machining characteristics. The distribution of the magnetic and electric fields in the polishing area is simulated using the finite element analysis software, and the machining experiments of micro groove were conducted to confirm the simulation results. Experimental results indicate that the material removal rate increases first and decreases afterwards with the increase of the cone angle, and the section width of micro groove increases but the section depth of micro groove shows a fluctuation phenomenon within a certain range. The intensities of the electric and magnetic fields on the tip of the conical tool with the 45° cone angle are at a larger level in the five tools, which is helpful to form a stable tiny-grinding wheel based on the EMR effect and obtain a better machining effect, so the tool with the 45° cone angle is an effective and ideal machining tool for the machining of 3D microstructure.

Abstract: Electro-magneto-rheological (EMR) fluids, which exhibit Newtonian behavior in the absence of a magnetic field, are abruptly transformed within milliseconds into a Bingham plastic under an applied magnetic field, called the EMR effect. Based on this effect, the particle-dispersed EMR fluid is used as a special instantaneous bond to cohere abrasive particles and magnetic particles together so as to form a dynamical, flexible tiny-grinding wheel to machine micro-groove on the surface of optical glass. Experiments were conducted to reveal the effects of process parameters, such as the feed rate of the horizontal worktable, feeding of the Z axis, machining time and machining gap, on material removal rate of glass. The results indicate that the feed rate of the worktable at horizontal direction has less effect on material removal rate, which shows a fluctuation phenomenon within a certain range. The feed rate of the Z axis directly influences the machining gap and leads to a remarkable change on material removal rate. Larger material removal rate can be obtained when the feeding frequency of Z direction is one time per processing. With the increase of rotation speed of the tool, material removal rate increases firstly and decreases afterwards, and it gets the maximum value with the rotation speed of 4800 rev/min. The machining time is directly proportional to material removal amount, but inversely proportional to material removal rate. Furthermore, material removal rate decreases with the increase of the machining gap between the tool and the workpiece. On the basis of above, the machining mode with the tiny-grinding wheel based on the EMR effect is presented.

Abstract: Based on the analysis of the machining process of magnetorheological finishing with the tiny-grinding wheel cluster, the motion model of abrasive in the tiny-grinding wheel cluster was proposed to describe the motion trajectory and the dwell time of abrasive relative to the surface of workpiece. Then, the experiment was applied to study the effects of the motion trajectory and the dwell time on surface quality and machining efficiency of the workpiece. According to the analysis, a method to improve surface quality and machining efficiency in MRF with the tiny-grinding wheel cluster was presented.

Abstract: A new tiny-grinding wheel cluster polishing method based on the Magnetorheological (MR) effect is presented to polish optical glass in this paper and some process experiments were conducted to reveal the influence of magnetic field strength, the content of carbonyl iron in the MR fluid and the speed of polishing disc on the material removal rate and the surface roughness of the glass workpiece. The results indicate that when the external magnetic field is applied, the material removal rate of the workpiece improves rapidly but the surface roughness increases slightly. When the Magnetic field strength is 100 Gs and the content of carbonyl iron is 3.5%, the material removal rate improves by a factor of 16.8% compared with that of the conventional polishing methods with dissociative abrasive particles, while the surface roughness of the workpiece increases unobviously.

Abstract: When grinding the revolving curved surface with Arc Envelope Grinding Method, the different curvatures in the convex and concave surfaces make a great difference in the surface roughness. In order to solve this problem, the relationship among envelope height, feeding rate, rotational speed and curvature of workpiece was analyzed based on equal-envelope-height grinding method. The results presented that, low feeding rate of grinding wheel and high rotational speed of workpiece were helpful to obtain smaller envelope height. And the smaller the radius of workpiece curvature, the more different the surface roughness. Besides, it was an effective method to solve this problem by changing feeding rate. The feeding rate should be changed directly proportionally to radius of workpiece curvature. Then, the experimental results indicate that, the fluctuation ratio of surface roughness with variable feeding rate is reduced to 4.896% from 26.17% with constant feeding rate. It proves the validity of hypothesis.

Abstract: The design and machining quality of mold core of luminaire reflector is the key to luminaire manufacturing. According to the structural characteristics of the mold core with axisymmetric uniform-distribution reflecting cells, the mathematical model with five-axis NC programming of this mold core was established. Based on five-axis CNC machine tools with dual rotary tables, then, the NC automatic programming calculation for this mold core was researched. Besides, a simple three-dimensional entity simulation was discussed. In this way, the three-dimensional entity simulation of automatic programming and processing in 5-axis NC machining of this mold core was realized.