Papers by Author: Dong Hui Wen

Abstract: This paper give some literatures for the technology of fluid polishing. Methods of fluid polishing using for optics curved surface, ultra-smooth plane and inner surface of non-circular curved surface. Each method is explained by above classifications, and some domestic cases which can produce ultra-smooth surface in different conditions, parts and technical parameters is listed and evaluated.

Abstract: This paper reviews three methods used to evaluate the uniformity in the lapping process. The first one evaluates the uniformity in lapping process according to studying the uniformity of lapping trajectory. The second one, compared with the measurement pattern based on polar coordinate, explains the advantages of Cartesian -based coordinate pattern in evaluating the lapping uniformity. The last one develops a model to calculate material removal in the lapping process and indicates the uniformity by calculating the material removal. These methods evaluate the uniformity in lapping process from different views, respectively, but each method still has various drawbacks. Therefore, further researches must be carried out to improve the system used to evaluate the uniformity in the lapping process.

Abstract: Ceramic materials are widely used in the fields of aviation, chemical industry, military, machinery, electronics, so there are so many researches on ceramic materials. This article is mainly about ceramic sample preparation by polishing process for nano-indentation, taking Alumina ceramic and Zirconia ceramic for example. As we know, nano-indentation test is an effective mean to study materials. It is concluded that after polishing, the ceramic surface roughness can reach Ra<10nm and maximum scratches<1nm, flatness<1μm, we can get good quality surface, that well meets the surface requirements in nano-indentation.

Abstract: The fast development of SAW requests higher quality surface of CVD diamond films. Nowadays the mechanical lapping method is one important way to polish CVD diamond films, but the processing cost is high due to the low machining quality and efficiency. This paper reports a new accelerant lapping technology base on mechanical lapping and exploratory studies the role of three kinds of metal of the iron, titanium and nickel in the process of lapping. Firstly, ANSYS/LS_DYNA was used to simulate the process of friction and cutting between the CVD diamond films and abrasive plate of different material to analyze the temperature distributing on the interface and weather it is helpful for lapping. Then, experiment researches were carried out using the abrasive plate with different accelerant materials ratio. The results indicate that titanium is the most potent accelerant for polishing, followed by iron and then nickel. Experimental study also found that the accelerant lapping can carried out effectively by using the abrasive plate made of different metallic materials as accelerant to the diamond film grinding.

Abstract: This paper discussed the polishing characteristic of single crystal sapphire (0001) when using 100°C vapor as polishing liquid and cedar wood as polishing pad. Surface roughness and scratch were compared before and after hydration polishing process. For 20 hours hydration polishing, both XRD and surface texture show that sapphire surface was changed in micro-structure and texture, even with minor scratch on the hydration polished surface, surface roughness could be decreased to Rt6.74 in X direction and Rt7.64nm in Y direction, it is about 2 nm surface layer was removed during hydration polishing.

Abstract: Accelerant polishing is a new polishing technique based on the principle of diamond graphitization. It makes full use of the catalysis of transition metal such as Fe, Ti. In this paper, it researches on the trend of the graphitization of CVD diamond film at different temperature by DTA, TG, DTG and Raman spectra analysis. The results show that accelerant polishing technique can reduce the required conditions of graphitization, and carry out the graphitization reaction at a low temperature.

Abstract: A new trajectory and uniformity was studied for single lapping process, kinematic theory analysis trajectories of the workpiece under the mode driven by swing motion. According to the theoretical analysis on lapping trajectory and simulated results, uniformity during swing driven lapping process is better than tranditional lapping process, angle rotation ratio between lapping plate and swing plate has great effect on lapping uniformity, when rotation speed of lapping plate is three times to that of swing plate, best uniformity could be gotten during lapping process.

Abstract: In this article, we propose a tool wear image segmentation algorithm based on Markov Random Field model. In this algorithm, the wear area was divided into wear area, background area and body area, in terms of the MAP (maximum a posteriori) criterion, and we got the pre-segmentation image. Afterwards, the aiming area (region B) was segmented out from the wear area by using peak-band algorithm and the edges are integrated in mathematical morphology theorem. As a result, we obtained an integrated tool wear region. Experiments indicate that the segmentation algorithm can be used to evaluate the degree of tool wear and applied to synchronously monitor tool wear condition effectively.

Abstract: Effect of lapping speed, plate material and crystal orientation on material removal rate and surface roughness were investigated by experiments and Taguchi Methods. Experimental results show both materials remove rate and surface roughness could be finished by using sythetic copper lapping plate with w3.5 cubic boron nitride abrasive than that for thin plate. Materials removal rate and surface roughness have no much difference for different crystal orientation as A-plane, C-plane and M-plane with experimental parameter conditions, lapping speed would be recommonded to not over 40rpm.

Abstract: This paper analyses the kinetic trajectory of abrasives both in initiative driving mode and passive driving mode, and the uniformity of lapping trajectory of the two opposite drive modes is discussed, respectively. The imperative relation between the kinematic trajectory and the uniformity is researched in this paper, as well as the simulation of the lapping trajectory.