毕业设计外文资料翻译
题 目 POLISHING OF CERAMIC TILES
抛光瓷砖 学 院 材料科学与工程 专 业 复合材料与工程 班 级 复材0802 学 生 学 号 20080103114 指导教师
二〇一二年三月二十八日
济南大学毕业设计外文资料翻译
MATERIALS AND MANUFACTURING PROCESSES, 17(3), 401–413 (2002)
POLISHING OF CERAMIC TILES
C. Y. Wang,* X. Wei, and H. Yuan
Institute of Manufacturing Technology, Guangdong University ofTechnology,
Guangzhou 510090, P.R. China
ABSTRACT
Grinding and polishing are important steps in the production of decorative vitreous ceramic tiles. Different combinations of finishing wheels and polishing wheels are tested to optimize their selection. The results show that the surface glossiness depends not only on the surface quality before machining, but also on the characteristics of the ceramic tiles as well as the performance of grinding and polishing wheels. The performance of the polishing wheel is the key for a good final surface quality. The surface glossiness after finishing must be above 208 in order to get higher polishing quality because finishing will limit the maximum surface glossiness by polishing. The optimized combination of grinding and polishing wheels for all the steps will achieve shorter machining times and better surface quality. No obvious relationships are found between the hardness of ceramic tiles and surface quality or the wear of grinding wheels; therefore, the hardness of the ceramic tile cannot be used for evaluating its machinability.
Key Words: Ceramic tiles; Grinding wheel; Polishing wheel - 2 -
济南大学毕业设计外文资料翻译
INTRODUCTION
Ceramic tiles are the common decoration material for floors and walls of hotel, office, and family buildings. Nowadays, polished vitreous ceramic tiles are more popular as decoration material than general vitreous ceramic tiles as they can
*Corresponding author. E-mail: cywang@gdut.edu.cn
401
Copyright q 2002 by Marcel Dekker, Inc. www.dekker.com have a beautiful gloss on different colors. Grinding and polishing of ceramic tiles play an important role in the surface quality, cost, and productivity of ceramic tiles manufactured for decoration. The grinding and polishing of ceramic tiles are carried out in one pass through polishing production line with many different grinding wheels or by multi passes on a polishing machine, where different grinding wheels are used.
Most factories utilize the grinding methods similar to those used for stone machining although the machining of stone is different from that of ceramic tiles. Vitreous ceramic tiles are thin, usually 5–8mm in thickness, and are a sintered material,which possess high hardness, wear resistance, and brittleness. In general, the sintering process causes surface deformation in the tiles. In themachining process, the ceramic tiles are unfixed and put on tables. These characteristics will cause easy breakage and lower surface quality if grinding wheel or grinding parameters are unsuitable. To meet the needs of ceramic tiles machining, the machinery, grinding parameters (pressure, feed speed, etc.), and grinding wheels (type and mesh size of abrasive, bond, structure of grinding wheel, etc.) must be optimized. Previous works have been reported in the field of grinding ceramic and stone[1 – 4]. Only a few reports have mentioned ceramic tile machining[5 – 8], where the grinding mechanism of ceramic tiles by scratching and grinding was studied. It was pointed out that the grinding mechanism of ceramic tiles is similar to that of other brittle materials. For vitreous ceramic tiles, removing the plastic deformation grooves, craters (pores), and cracks are of major concern, which depends on the micro-structure of the ceramic tile, the choice of grinding wheel and processing parameters, etc. The residual cracks generated during sintering and rough grinding processes, as well as thermal impact cracks caused by the transformation of quartz crystalline phases are the main reasons of tile breakage during processing. Surface roughness Ra and glossiness are different measurements of the surface quality. It is suggested that the surface roughness can be used to control the surface quality of rough grinding and semi-finish grinding processes, and the surface glossiness to assess the quality of finishing and polishing processes. The characteristics of the - 3 -
济南大学毕业设计外文资料翻译
grinding wheels, abrasive mesh size for the different machining steps, machining time, pressure, feed, and removing traces of grinding wheels will affect the processing of ceramic tiles[9].
In this paper, based on the study of grinding mechanisms of ceramic tiles, the manufacturing of grinding wheels is discussed. The actions and optimization of grinding and polishing wheels for each step are studied in particular for manualpolishing machines.
GRINDING AND POLISHING WHEELS FOR CERAMIC TILE
MACHINING
The machining of ceramic tiles is a volume-production process that uses significant numbers of grinding wheels. The grinding and polishing wheels for
ceramic tile machining are different from those for metals or structural ceramics. In this part, some results about grinding and polishing wheels are introduced for better understanding of the processing of ceramic tiles.
Grinding and Polishing Wheels
Ceramic tiles machining in a manual-polishing machine can be divided into four steps—each using different grinding wheels. Grinding wheels are marked as 2#, 3#, and 4# grinding wheels, and 0# polishing wheel; in practice, 2# and 3# grinding wheels are used for flattening uneven surfaces. Basic requirements of rough grinding wheels are long life, high removal rate, and lower price. For 2# and 3# grinding wheels, SiC abrasives with mesh #180 (#320) are bonded by magnesium oxychloride cement (MOC) together with some porous fills, waterproof additive, etc. The MOC is used as a bond because of its low price, simple manufacturing process, and proper performance.
The 4# grinding wheel will refine the surface to show the brightness of ceramic
tile. The GC#600 abrasives and some special polishingmaterials, etc., are bonded by MOC. In order to increase the performance such as elasticity, etc., of the grinding wheel, the bakelite is always added. The 4# grinding wheels must be able to rapidly eliminate all cutting grooves and increase the surface glossiness of the ceramic tiles. The 0# polishing wheel is used for obtaining final surface glossiness, which - 4 -
济南大学毕业设计外文资料翻译
is made of fine Al2O3 abrasives and fill. It is bonded by unsaturated resin. The polishing wheels must be able to increase surface glossiness quickly and make the glossy ceramic tile surface permanent.
Manufacturing of Magnesium Oxychloride Cement Grinding Wheels
After the abrasives, the fills and the bond MOC are mixed and poured into the models for grinding wheels, where the chemical reaction of MOC will solidify the shape of the grinding wheels. The reaction will stop after 30 days but the hardness of grinding wheel is essentially constant after 15 days. During the initial 15-day period, the grinding wheels must be maintained at a suitable humidity and temperature.
For MOC grinding wheels, the structure of grinding wheel, the quality of abrasives, and the composition of fill will affect their grinding ability. All the factors related to the chemical reaction of MOC, such as the mole ratio of MgO/MgCl2, the specific gravity of MgCl2, the temperature and humidity to care the cement will also affect the performance of the MOC grinding wheels.
Mole Ratio of MgO/MgCl2
When MOC is used as the bond for the grinding wheels, hydration reaction takes place between active MgO and MgCl2, which generates a hard XMgeOHT2·YeMgCl2T·ZH2O phase. Through proper control of the mole ratio of MgO/MgCl2, a reaction product with stable performance is formed. The bond is composed of 5MgeOHT2·eMgCl2T·8H2O and 3MgeOHT2·eMgCl2T·8H2O: As the former is more stable, optimization of the mole ratio of MgO/MgCl2 to produce more 5MgeOHT2·eMgCl2T·8H2O is required. In general, the ideal range for the mole ratio of MgO/MgCl2 is 4–6. When the contents of the active MgO and MgCl2 are known, the quantified MgO and MgCl2 can be calculated.
Active MgO
The content of active MgO must be controlled carefully so that hydration reaction can be successfully completed with more 5MgeOHT2·eMgCl2T·8H2O: If the content of active MgO is too high, the hydration reaction time will be too short with a large reaction heat, which increases too quickly. The concentrations of the thermal stress can cause generation of cracks in the grinding wheel. On the - 5 -
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