毕业设计外文文献翻译抛光瓷砖.doc

2012毕业设计外文文献翻译抛光瓷砖 毕业设计外文资料翻译题 目 抛光瓷砖 学 院 专 业 班 级 学 生 学 号 指导教师 二一二年月日MATERIALS AND MANUFACTURING PROCESSES 17 3 401413 2002 POLISHING OF CERAMIC TILESC Y Wang X Wei and H YuanInstitute of Manufacturing Technology Guangdong University ofTechnology Guangzhou 510090 PR ChinaABSTRACTGrinding 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 imum 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 machinabilityKey Words Ceramic tiles Grinding wheel Polishing wheelINTRODUCTIONCeramic tiles are the common decoration material for floors and walls ofhotel office and family buildings Nowadays polished vitreous ceramic tiles are more popular as decoration material than general vitreous ceramic tiles as they canCorresponding author E-mail cywangcom401Copyright q 2002 by Marcel Dekker Inc comhave a beautiful gloss on different colors Grinding and polishing of ceramic tilesplay an important role in the surface quality cost and productivity of ceramic tilesmanufactured for decoration The grinding and polishing of ceramic tiles arecarried out in one pass through polishing production line with many differentgrinding wheels or by multi passes on a polishing machine where differentgrinding wheels are usedMost factories utilize the grinding methods similar to those used for stonemachining although the machining of stone is different from that of ceramic tilesVitreous ceramic tiles are thin usually 58mm in thickness and are a sinteredmaterialwhich possess high hardness wear resistance and brittleness In general thesintering process causes surface deformation in the tiles In themachining process theceramic tiles are unfixed and put on tables These characteristics will cause easybreakage and lower surface quality if grinding wheel or grinding parameters areunsuitable To meet the needs of ceramic tiles machining the machinery grindingparameters pressure feed speed etc and grinding wheels type and mesh size ofabrasive bond structure of grinding wheel etc must be optimizedPrevious works have been reported in the field of grinding ceramic andstone1 4 Only a few reports have mentioned ceramic tile machining5 8 wherethe grinding mechanism of ceramic tiles by scratching and grinding was studied Itwas pointed out that the grinding mechanism of ceramic tiles is similar to that ofother brittle materials For vitreous ceramic tiles removing the plastic deformationgrooves craters pores and cracks are of major concern which depends on themicro-structure of the ceramic tile the choice of grinding wheel and processingparameters etc The residual cracks generated during sintering and rough grindingprocesses as well as thermal impact cracks caused by the transformation of quartzcrystalline phases are the main reasons of tile breakage during processing Surfaceroughness Ra and glossiness are different measurements of the surface quality It issuggested that the surface roughness can be used to control the surface quality ofrough grinding and semi-finish grinding processes and the surface glossiness toassess the quality of finishing and polishing processes The characteristics of thegrinding wheels abrasive mesh size for the different machining steps machiningtime pressure feed and removing traces of grinding wheels will affect theprocessing of ceramic tiles9In this paper based on the study of grinding mechanisms of ceramic tiles themanufacturing of grinding wheels is discussed The actions and optimization ofgrinding and polishing wheels for each step are studied in particular for manualpolishingmachinesGRINDING AND POLISHING WHEELS FOR CERAMIC TILEMACHININGThe machining of ceramic tiles is a volume-production process that usessignificant numbers of grinding wheels The grinding and polishing wheels forceramic tile machining are different from those for metals or structural ceramicsIn this part some results about grinding and polishing wheels are introduced forbetter understanding of the processing of ceramic tilesGrinding and Polishing WheelsCeramic tiles machining in a manual-polishing machine can be divided intofour stepseach using different grinding wheels Grinding wheels are marked as2 3 and 4 grinding wheels and 0 polishing wheel in practice 2 and 3grinding wheels are used for flattening uneven surfaces Basic requirements ofrough grinding wheels are long life high removal rate and lower price For 2 and3 grinding wheels SiC abrasives with mesh 180 320 are bonded bymagnesium oxychloride cement MOC together with some porous fillswaterproof additive etc The MOC is used as a bond because of its low pricesimple manufacturing process and proper performanceThe 4 grinding wheel will refine the surface to show the brightness of ceramictile The GC600 abrasives and some special polishingmaterials etc are bonded byMOC In order to increase the performance such as elasticity etc of the grindingwheel the bakelite is always added The 4 grinding wheels must be able to rapidlyeliminate all cutting grooves and increase the surface glossiness of the ceramic tilesThe 0 polishing wheel is used for obtaining final surface glossiness whichis made of fine Al2O3 abrasives and fill It is bonded by unsaturated resin Thepolishing wheels must be able to increase surface glossiness quickly and make theglossy ceramic tile surface permanentManufacturing of Magnesium Oxychloride Cement Grinding WheelsAfter the abrasives the fills and the bond MOC are mixed and poured into themodels for grinding wheels where the chemical reaction of MOC will solidify theshape of the grinding wheels The reaction will stop after 30 days but the hardness ofgrinding wheel is essentially constant after 15 days During the initial 15-day periodthe grinding wheels must be maintained at a suitable humidity and temperatureFor MOC grinding wheels the structure of grinding wheel the quality ofabrasives and the composition of fill will affect their grinding ability All thefactors related to the chemical reaction of MOC such as the mole ratio ofMgOMgCl2 the specific gravity of MgCl2 the temperature and humidity to carethe cement will also affect the performance of the MOC grinding wheelsMole Ratio of MgOMgCl2When MOC is used as the bond for the grinding wheels hydration reactiontakes place between active MgO and MgCl2 which generates a hardXMgeOHT2·YeMgCl2T·ZH2O phase Through proper control of the mole ratio ofMgOMgCl2 a reaction product with stable performance is formed The bond iscomposed of 5MgeOHT2·eMgCl2T·8H2O and 3MgeOHT2·eMgCl2T·8H2O As theformer is more stable optimization of the mole ratio of MgOMgCl2 to producemore 5MgeOHT2·eMgCl2T·8H2O is required In general the ideal range for themole ratio of MgOMgCl2 is 46 When the contents of the active MgO andMgCl2 are known the quantified MgO and MgCl2 can be calculatedActive MgO The content of active MgO must be controlled carefully so that hydrationreaction can be successfully completed with more 5MgeOHT2·eMgCl2T·8H2O Ifthe content of active MgO is too high the hydration reaction time will be too shortwith a large reaction heat which increases too quickly The concentrations of thethermal stress can cause generation of cracks in the grinding wheel On thecontrary if the content of active MgO is too low the reaction does not go tocompletion and the strength of the grinding wheel is decreasedFills and AdditivesThe fills and additives play an important role in grinding wheels Some porous fills must be added to 2 and 3 grinding wheels in order to improve the capacity to contain the grinding chips and hold sufficient cutting grit Waterproof additives such as sulfates can ensure the strength of grinding wheels in processing under water condition Some fills are very effective in increasing the surface quality of ceramic tile but the principle is not clearManufacturing of Polishing WheelsFine Al2O3 and some soft polishing materials such as Fe2O3 Cr2O3 etc are mixed together with fills Unsaturated resin is used to bond these powders where a chemical reaction takes place between the resin and the hardener by means of an activator The performance of polishing wheels depends on the properties of resin and the composition of the polishing wheel In order to contain the fine chips which are generated by micro-cutting some cheap soluble salt can be fed into the coolant On the surface of the polishing wheel the salt will leave uniform pores which not only increase the capacity to contain chips and self-sharpening of the polishing wheel but also improves the contact situation between polishing wheel and ceramic tilesExperimental ProcedureTests were carried out in a special manual grinding machine for ceramictiles Two grinding wheels were fixed in the grinding disc that was equipped to thegrinding machine The diameter of grinding disc was 255 mm The rotating speedof the grinding disc was 580 rpm The grinding and polishing wheels are isoscelestrapezoid with surface area 315 cm2 the upper edge 2 cm base edge 5 cmheight 9 cm The pressure was adjusted by means of the load on the handle fordifferent grinding procedures A zigzag path was used as the moving trace for thegrinding disc To maintain flatness and edge of the ceramic tiles at least one thirdof the tile must be under the grinding disc During the grinding process sufficientwater was poured to both cool and wash the grinding wheels and the tilesFour kinds of vitreous ceramic tiles were examined as shown in Table 1Two different sizes of ceramic A A400 size 400 400 5mm3T and A500 size 500 500 5mm3T were tested to understand the effect of the tile size Forceramic tile B or C the size was 500 500 5mm3 The phase composition of thetiles was determined by x-ray diffraction technique Surface reflection glossinessand surface roughness of the ceramic tiles and the wear of grinding wheels were measuredThe grinding and polishing wheels were made in-house The 2 grindingwheels with abrasives of mesh 150 and 3 grinding wheels with mesh 320 wereused during rough grinding Using the ceramic tiles with different surfacetoughness ground by the 2 grinding wheel for 180 sec the action of the 3grinding wheels were tested The ceramic tile was marked as A500-1 or B500-1C500-1 A400-1 with higher initial surface toughness or A500-2 or B500-2C500-2 A400-2 with lower initial surface toughnessTwo kinds of finishing wheels 4A and 4B were made with the same structure abrasivity and process but different composition of fills and additives Only in 4B a few Al2O3 barium sulfate and magnesium stearate were added for higher surface glossiness The composition of the polishing wheels 0A and 0B were different as well In 0B a few white alundum average diameter 1mm barium sulfate and chrome oxide were used as polishing additives specially After ground by 4A or 4B grinding wheel the ceramic tiles were polished with 0A or 0B The processing combinations with 4 grinding wheels and 0Table 1 Properties of Ceramic TilesCeramic TilesHV01CrystallineGrain Size mm Mullite vol Quartz vol VitreousMass vol Porosity vol Pore Size mm A400A500661010-3032-4015-1835-403-55-20B500710610-3032-4010-1335-405-73-50C500614210-3012-1510-1335-403-55-30polishing wheels were marked as 4A0A 4A0B 4B0A 4B0B for each ceramic tileRESULTS AND DISCUSSIONSEffects of 2 and 3 Grinding WheelsSurface Quality In rough grinding with a 2 grinding wheel the surface roughness for all the tiles asymptotically decreases as the grinding time increases see Fig 1 The initial asymptote point of this curve represents the optimized rough grinding time as continued grinding essentially has no effect on the surface roughness In these tests the surface roughness curves decrease with grinding time and become smooth at 120 sec The final surface quality for different kinds of ceramic tiles is slightly different In terms of the initial size of the tile the surface roughness of ceramic tile A400 e 400 5mm3T is lower than that of A500 e500 500 5mm3T The surface roughness of ceramic tile B500 rapidly drops as the grinding time increases Thus it is easier to remove surface material from the hardest of thethree kinds of the ceramic tiles Table 1 However as the final surface roughness of ceramic tile A500 is the same as that of ceramic tile C500 the hardness of theceramic tile does not have a direct relationship with the final surface qualityIn the 3 grinding wheel step all craters and cracks on the surface of ceramic tiles caused by the 2 grinding wheel must be removed If residual cracks and craters exist it will be impossible to get a high surface quality in the next step The surface roughness obtained by the 2 grinding wheel will also affect the surfaceFigure 1 Surface roughness of several ceramic tiles as a function of grinding time for 2 grindingwheelquality of next grinding step by the 3 grinding wheel In Fig 2 the actions of the 3 grinding wheels are given using the ceramic tiles with different initial Ra which were ground by the 2 grinding wheel for 180 sec The curves of surface vs grinding time rapidly decrease in 60 sec Asymptotic behavior essentially becomes constant after 60 sec In general the larger the initial surface roughness the worse the final surface roughness For example for ceramic tile B500-1 the initial Ra was 153mm the finial Ra was 059mm after being ground by the 3 grinding wheel When the initial Ra was 206mm for ceramic tile B500-2 the finial Ra was 067mmIn Ref 8 we studied the relations between abrasive mesh size and evaluation indices of surface quality such as surface roughness and surface glossiness In rough grinding the ground surface of ceramic tile show