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1、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 polishi

2、ng 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 c

3、haracteristics 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

4、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 grin

5、ding 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

6、 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 surfa

7、ce 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 usedMo

8、st 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

9、 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 til

10、es 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

11、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

12、 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

13、 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 glossines

14、s 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

15、 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

16、 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 o

17、f 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 us

18、ed 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

19、 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 elasticit

20、y 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 fil

21、l 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

22、 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 humi

23、dity 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 an

24、d 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 hardXMgeOHT2YeMgCl2TZH2O phase Through proper control of the

25、 mole ratio ofMgOMgCl2 a reaction product with stable performance is formed The bond iscomposed of 5MgeOHT2eMgCl2T8H2O and 3MgeOHT2eMgCl2T8H2O As theformer is more stable optimization of the mole ratio of MgOMgCl2 to producemore 5MgeOHT2eMgCl2T8H2O is required In general the ideal range for themole

26、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 5MgeOHT2eMgCl2T8H2O Ifthe content of active

27、 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 tocompleti

28、on 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 Waterp

29、roof 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 s

30、uch 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 pol

31、ishing 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

32、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 grind

33、ing 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 zigz

34、ag 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 vitre

35、ous 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 dif

36、fraction 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 grind

37、ing 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

38、 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 w

39、heels 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 an

40、d 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 4B0

41、A 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 represent

42、s 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 te

43、rms 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

44、 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 c

45、eramic 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

46、 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 t

47、ime 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 grin

48、ding 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 shows f

49、racture craters These craters scatter the light so that the surface glossiness values are almost constant at a low level It is difficult to improve the surface glossiness afterthese steps Figure 3 shows the slow increase in surface glossiness with time by means of the 3 grinding wheel It can be seen

50、 that the glossiness of ceramic tile B500-1 is the highest The surface glossiness of ceramic tile A400-1 is better than that of A500-1 because the effective grinding times per unit area for former is longer than for latter These trends are similar to those for surface roughness inFig 2Wear of Grindi

51、ng WheelsThe wear of grinding wheels is one of the factors controlling the machining cost As shown in Fig 4 the wear of grinding wheels is proportional to grindingFigure 2 Surface roughness of several ceramic tiles as a function of grinding time for 3 grindingwheelFigure 3 Surface glossiness of seve

52、ral ceramic tiles as a function of grinding time by 3 grindingwheeltime for both the grinding wheels and the three types of ceramic tiles The wear rate of the 3 grinding wheel is larger than the 2 grinding wheel It implies that the wear resistance of the 3 grinding wheel is not as good as 2 for cons

53、tant grinding time of 180 sec When the slope of the curve is smaller life of thegrinding wheels will be longer Comparison of the ceramic tiles hardness Table 1 with the wear resistance behavior in Fig 4 does not reveal a strong dependency Therefore the hardness of the ceramic tile cannot be used to

54、distinguish the machinability The difference ofFigure 4 Wear of grinding wheels of several ceramic tiles as a function of grinding time for 2 and3 grinding wheelsinitial surface roughness of ceramic tile will affect the wear of grinding wheel In Fig 4 the wear of the 3 grinding wheel for ceramic til

55、e B500-1 is smaller than that for ceramic tile B500-2 The initial surface roughness of the latter is higher than that of the former so that additional grinding time is required to remove the deeper residual craters on the surface Improvement of the initial surface roughness can be the principal meth

56、od for obtaining better grinding quality and grinding wheel life during rough grindingEffects of 4 Grinding Wheels and 0 Polishing WheelsSurface QualityThe combination and the performance of 4 grinding and 0 polishingwheels show different results for each ceramic tile The grinding quality vs grindin

57、g polishing time curves are presented in Fig 5 where all the ceramic tiles were previously ground by 2 and 3 grinding wheels to the same surface qualityThe surface glossiness is used to assess surface quality because the surface roughness is nearly constant as finishing or polishing time increases8

58、In this test the ceramic tile A400 were fast ground by 4A and 4B grinding wheels Fig 5 a The surface glossiness increased rapidly during the initial 90 sec and then slowly increased The surface glossiness by grinding wheel 4B is higher than by 4A Afterwards polishing was done by four different combi

59、nations of finishing wheel and polishing wheel By means of polishing wheels 0A and 0B we processed the surface finished by 4A grinding wheel described as 4A0A and 4A0B in Fig 5 and the surface finished by 4B grinding wheel described as 4B0A and 4B0B in Fig 5 The curves of surface glossiness vs polis

60、hing time show parabolic behavior After 60 sec of polishing the surface glossiness reaches to 508 then slowly increases The polishing wheel 0B gives a better surface quality than 0AIn Fig 5 a the imum surface glossiness of ceramic tile A400 is about 75 by 4B0B The relation between initial surface gl

61、ossiness and the final surface quality is not strong The effect of pre-polishing surface glossiness can be observed by 0B polishing wheel as polishing ceramic tile A500 Fig 5 b The imum surface glossiness that can be achieved is 748 in 240 sec by 4A0B or 4B0B This value is lower than that of ceramic

62、 tile A400 Fig 5 a The final surface glossiness by 4A grinding wheel is highly different from that by 4B grinding wheel for ceramic tile B500 as shown in Fig 5 c but the final polishing roughness is the same when 0A polishing wheel is used The better performance of 0B polishing wheel is shown becaus

63、e the surface glossiness canincrease from 17 to 228 in 30 sec The imum surface glossiness is 658 by 4B 0B The curves of polishing time vs surface glossiness in Fig 5 d present the same results as polishing of ceramic tile B500 Fig 5 c With 0A polishingFigure 5 Surface glossiness for ceramic tiles a

64、A400 b A500 c B500 and d C500 as afunction of grinding polishing time for 4 grinding wheels and 0 polishing wheelswheel the action of pre-polishing surface glossiness is significant The best value of surface glossiness in 240 sec is 708 by 4B0B as polishing ceramic tile C500 The results discussed earlier describe that the surface glossiness by 0 polishing wheel will depend not only on the pre-polishing