【机械类毕业论文中英文对照文献翻译】磨削方式对单晶硅表面磨削温度的影响
【机械类毕业论文中英文对照文献翻译】磨削方式对单晶硅表面磨削温度的影响,机械类毕业论文中英文对照文献翻译,机械类,毕业论文,中英文,对照,对比,比照,文献,翻译,磨削,方式,对于,单晶硅,表面,温度,影响
STUDIES OF SURFACE GRINDING TEMPERATURE AFFECTED BY DIFFERENT GRINDING WAYS OF SILICON WAFERAbstract: The surface g grinding temperature o f the silicon wafer ground by diamond w heels is studied. Rudimentally, the properties o f the surface grinding temperature generated by two grinding methods, ground by straight and cup wheels respectively , are analyzed. In addition, considering the effects o f grain size and grinding depth on surface grinding temperature during these two grinding processes, significantresults and conclusions are obtained from experimental research.Keywords: surface grinding temperature, straight wheel, cup wheel, silicon waferThe machining technique of silicon wafers has gradually become one o f the progressive projects in recent years. With the successful production of large size silicon wafers, researchers all over the world have paid more at tention to the machining techniques of silicon wafersAccording to the ductile grinding principle of brittle materials, remarkable developments have been achieved to make the precision machining of large size silicon wafers become true by adopting the cup wheel surface grinding technique, which is a high efficiency precision machining way and has wide application in hard-brittle material machining fields. To prevent the silicon wafer from burning , the research work of surface grinding temperature should not be ignored. Most of the former research works of surface grinding temperature focused on the straight wheel grinding process mainly . In the difference between these two machining principles, there are some distinct ions in surface grinding temperature, so it is necessary to understand the difference of surface grinding temperature between the cup wheel grinding and the straight wheel grinding processes. At the same time, the relevant researchwork is meaningful to the application of the cup wheel grinding technique.1.Comparison of Surface Grinding Techniques between Cup Wheel and Straight WheelFig. 1 shows the surface grinding method with a straight wheel. The contact length between the w heel and the workpiece, which is closely related to grinding directions and grinding depth, is variable with grinding parameters and has significant influence on grinding heat . The intensity of the heat source will change with the contact length.Fig. 1Shape of grinding zone with straight wheelFig. 2 show s the surface grinding process with a cup wheel. The contact length between the wheel and the workpiece has little relation with grinding directions and grinding depth. For a given wheel , the contact length keeps constant within a certain rang e of grinding depths. As the cause of the moving heat source is regarded as a linear source based on the traditional grinding heat theory , hence, this theory does not suit the cup wheel grinding process for its grinding zone is an arc instead o f rectangle. Therefore, the grinding heat model for the cup wheel should be set up to meet the needs of this technology.Fig. 2Shape of grinding area with cup wheel2.Experimental Method, Apparatus and Conditions2. 1Experimental methodT he surface grinding temperature is measured with a thermocouple. Two pieces o f thin thermocouple slices of 0. 1mm thickness, made of standard thermocouple wires, are clamped between two parts of the workpiece and are insulated from the workpiece. When the wheel grinds the surface of the workpiece, the two slices,end points on the workpiece surface can be welded together as a node. Due to the small volume of this node, heat capacity is small enough. If the amplifying and recording instrument s react quickly enough, the response time is extremely short . The real grinding temperature can be measured accurately without furtherdeductive computing .2. 2ApparatusFig. 3 shows the experiment system. The thermocouple wires out of the workpiece are connected with a DC amplifier which enlarges the thermic signals 100 to 1 000 times. The signals are analyzed by a digital real-time oscilloscope, and recorded by a computer. The minute grinding depth is performed in 0. 1 um per step by a micro-feed system which is manufactured by our own laboratory. T he feed principle is shown in Fig . 3.The computer pro vides accurate digital signals to the amplifier. The amplified signal is transmit ted into a piezoquartz to perform micro-feed.Fig. 3Principle of measurement system2. 3Experimental conditionsT ab. 1 show s the experimental conditions by a straight wheel, while Tab. 2 by a cup wheel .Tab. 1 Equipment and parameters of surface grinding with a straight wheelGrinding machine HZ-63 horizontal surface grinderGrinding w heel resin bonded diamond shape: straight300 mm25 mm240# , W10Workpiece single crystal silicon 25 mm10 mm5 mmGrinding fluid noTab. 2Equipment and parameters of surface grinding with a cup wheelGrinding machine CG6125A latheGrinding w heel resin bonded diamondshape: cupouter diameter: 100 mminternal diameter : 90 mmabrasive size: 120# ,W28, W10Workpiece single crystal silicon 25 mm10 mm5 mmGrinding fluid water-based coolant3Experimental Results3. 1 Comparison of surf ace grinding temperature generated by straight wheel and cup wheelFig . 4 shows the real-recorded thermic voltage signal waveshape of the silicon wafer ground by a straight wheel (W10) . The grinding parameters are, grinding depth 3 um, table-speed 20 m/ min, plunge and dry grinding. The lasting time of the grinding thermic voltage wave varying from rapid ascending to desending gradually only lasts 0. 02 to 0.03s. This result indicates that the range of the high grinding temperature only last s a very short time on any point of the silicon wafer ground surface. T he rapid table-speed during the straight wheel grinding processes makes the grinding zone moving fast through the surface o f the workpiece. Little burn can be found on the workpiece surface.Fig. 4Signal waveshape ground by a straight wheelFig. 5 show s the thermic voltage wave of the silicon wafer ground by a cup w heel (W28) . The grinding parameters are as follows: grinding depth is 10 um, tablespeed is 12 mm/ min, and coolant is engaged. Compared with Fig . 4, the thermic voltage signal wave lasts about 12. 5 s from ascending to descending. Obviously ,the lasting time of the high temperature in the cup wheel grinding process is as long as several hundred times compared with the straight wheel grinding process.The longer time the high temperature lasts, the more influence the workpiece qualities will suffer by heat . A complementary test , in which the conditions are similar to Fig. 4 but the coolant , presents further evidence to above opinions. Serious result s appeared: extreme high temperature, cracks o n the workpiece surface, and the scorch of the adhesive between the workpiece and its supporter . These experimental results suggest that the coolant is essential to the cup wheel grinding process, and some suitable methods, such as decreasing the width of the cup wheel, choosing a proper coolant and dressing w heel in time, shouldbe adopted to reduce the generation of grinding heat .Fig. 5Signal waveshape ground by a cup wheel3. 2 Experimental phenomena and analysis during straight wheel grinding processThe surface grinding temperature of spark-out grinding was tested to observe the laws of surface grinding temperature during the elastic recovery process of the grinding system in which the actual grinding depth decreases gradually to zero . During this grinding process, the material removal mechanism might change and there will have some influence on the surface grinding temperature.Fig . 6 shows the relation between the surface grinding temperature and spark-out times. With the increase of spark-out times, surface grinding temperatures degrade step by step, finally to steady state.From the experiment result s, we have the following discussions.Fig. 6Relation of surf ace grinding temperature and spark-out timesFirst , at the sixth spark-out grinding time, the surface grinding temperature increases abnormally. Similar test s w ere repeated three times to avoid possible errors. The tests present similar abnormal resultsat the same time. There may exist sever al factor s causing the results, such as the abnormal contact of thermocouple node, etc. We attribute the results to the change of material removal mechanism. When the actualgrinding depth decreases with the spark-out grinding times, the material removal mechanism turns to ductile-mode from brittle-mode. In this process, the grinding force and temperature will have significant changes. The results also ex press that the ductile-mode grinding has not close relationship with grain-size. Proper conditions provided, a coarse grain size wheel can realize ductile-mode grinding , too . Because of the less number of grains around the coarse grain wheel periohery , the surface roughness ground by a coarse grain wheel is larger than that g round by a fine grain wheel .Second, according to Fig . 6, surface grinding temperatures tend to have a steady value after the sixth spark-out grinding process. That is to say, maybe there is not any material being removed from the workpiece,s surface. Thus there exist s a limit time of silicon wafer spark-out grinding .It is useless beyond the limit .Finally, after the sixth spar k-out grinding process, surface temperature also can be tested even if it is meaningless in fact . The tested temperatures keep constant on the whole even after the sixtieth spark-outgrinding . The grinding thermic voltage curve measured is shown in Fig.7.Fig. 7Signal waveshape after the sixth spark-out grindingIn contrast with Fig. 4, it is obvious that these two kinds of thermic voltage curve differ entirely . The fact that the thermic voltage curves change from one peak to multi-peaks ex presses that the grinding heat isgenerated by individual grains. Though, there is no actual grinding depth and no material removal, the wheel and workpiece contact anyway in the form of ploughing or scratching . There is still some energy transformedinto grinding heat . In order to verify the assumption that each peak in the multi-peak curve results from the sing le grain grinding intercourse, the relationship between the number of peaks and workpiece tables-peed is observed, as shown in Fig. 8.Fig. 8Relation between grain number and table speedT he faster the tables-peed is , the fewer the peak number is. This is because the contact time between the w heel and the workpiece becomes shorter with the increase of table-speed, so , the number of grain engagedinto grinding process decreases. The effective grain number can be measured through this method during the spark-out grinding process.3. 3Effect of grain size and grinding depth on surface grinding temperature3. 3. 1Surface grinding temperature caused by straight wheelFig . 9 shows the experimental relations between the surface grinding temperature of the silicon wafer and straight w heel grinding parameters that include grain size, grinding depth, up grinding and down grinding. The grinding wheel speed and the table-speed are kept constant , where the grinding wheel speed is 22. 8m/ s, table-speed is 8m/ min. From Fig . 9, we know that, at the same grinding depth, the surface grinding temperature ground by a fine g rain wheel is higherthan that by a coarse g rain wheel, in which a similar relation in grinding force was observed by other scholars . Though the surface grinding temperature increases with the grinding depth increasing, the increasingrates are different with grain size. When the grinding depth is smaller than 0. 02 mm for a 240# wheel, the surface grinding temperature increases slowly. When the grinding depth is over 0. 03 mm, the surfacegrinding temperature increases abruptly and causes burn of the workpiece. As to a wheel o f grain sizeW10, the surface grinding temperature grows quickly at a grinding depth of 0. 005 mm, but , when the grinding depth is higher than 0. 01 mm, the grinding process is unsteady , the surface grinding temperature increases abruptly, and the workpiece burn is found.Fig. 9Surface grinding temperature ground by straight wheel3. 3. 2Sur face grinding temperature caused by cup wheelT he cup w heel speed and the workpiece feed speed are constant . Experimental conditions are listed in T ab. 2. The rotation speed of the cup wheel is 1 500r / min, the feed r ate of the workpiece is 12 mm/ minand the grinding depth ranges from 0. 001 mm to 0. 01mm. The experimental result s are show n in Fig . 10. In the same straight w heel grinding process, the surface grinding temperature ground by a fine grain w heel is obviously higher than that by a coarse grain w heel .Moreover , the coolant has critical influence on the cup wheel grinding process. Without a coolant , the grinding heat will remain and accumulate in the workpiece, and finally, cause the unstability of the grinding process and workpiece burn.Fig. 10Surface grinding temperature ground by cup wheel4.Conclusions1) Ground by a cup w heel, the high temperature period lasts longer than that ground by a straight wheel. The coolant takes very important effect s to reduce the lasting time of high temperature.2) For both straight wheel and cup w heel, the surface grinding temperature ground by fine grains is higher than that by coarse grains.3) T he effective spark-out grinding times have a limit with a straight wheel . After the effective sparkout grinding times, there is some energy converted into grinding heat . T his process can last for a long time.4) T he experimental setups and methods can reflect the effective numbers of g rains during the sparkout grinding process with a straight wheel.References 1 Jaeger J C. Moving sources of heat and the temperature at sliding contacts J . Proc Roy Soc of New South Wales ,1982, 76: 203. 2 Kenichiro Imai, Hiroshi Hashimoto. Some fundamental findings in ductile grinding various brittle materials C . Proceedings of the ICPE,96 & 6th SJS SUT , 6163. 3 Pang N, Zhou ZX, Zheng H W. T he study of plastic ultrasonic grinding machining process in silicon wafer C . Proceedings of the IC PE, 96 & 6th SJ SSUT , 8386. 4 Zhan g C H, L in B. T he experiment al analysis of ELID grinding force in super -precision mirror finishing J . Aviation Precision Manufacturing Technology , 1998, 34: 811.磨削方式对单晶硅表面磨削温度的影响摘要: 研究金刚石砂轮磨削单晶硅片时的表面磨削温度. 针对平形砂轮和杯形砂轮两种不同平面磨削方式所产生的表面磨削温度特点进行了比较分析. 对砂轮粒度和磨削深度对这两种平面磨削方式的表面磨削温度的影响进行了试验研究, 得到了一些有意义的试验结果和结论.关键词: 表面磨削温度, 平形砂轮, 杯形砂轮, 单晶硅在硅晶片加工技术已逐渐成为近几年来大力发展的项目之一的今天,随着大尺寸硅片生产成功,世界各地的研究者们在对硅片的加工技术发展潜力的研究方面付出了更多的精力 根据韧性和脆性材料磨削的原则,在大尺寸硅片精密加工已经取得了显着的发展并获得成功,方法就是通过采用杯形砂轮表面研磨技术,这是一个高效率的精密加工方法,并已广泛应用于对脆性材料加工领域。为防止硅片烧毁,表面磨削温度的研究工作就显得不可忽略。前人对表面磨削温度研究的大部分主要是集中在圆盘砂轮加工工艺方面。对于这两个不同的加工原则,有一些表面磨削温度的区别,因此有必要了解杯形砂轮和圆盘砂轮磨削加工工艺不同的表面磨削温度。与此同时,有关的研究工作对于杯形砂轮磨削技术的应用是很有意义的。1、杯形砂轮和圆盘砂轮表面磨削技术的比较图1显示了圆盘砂轮表面磨削技术。车轮和工件之间的接触长度是与磨削深度、磨削方向和多变的研磨参数密切相关,而且对磨削热有着十分重要的影响。热源强度会随着接触长度的变化而变化。图2显示了杯形砂轮表面磨削技术。车轮和工件之间的接触长度与磨削方向和磨削深度很少有关系。对于一个给定的砂轮, 在某一磨削深度范围,接触长度保持常值。移动热源的原因被认为是一种线性源基于传统磨削热理论,因而, 在其圆弧代替激光束的矩形磨削区域,这一理论不适合与杯形砂轮磨削加工。因此,杯形砂轮的磨削热模型也应建立起来以迎合这项新技术需要。2.实验方法、仪器和条件2.1实验方法表面磨削温度通过使用热电偶测量。热电偶由两片薄0.1毫米厚度的标准热电偶丝制成,并被夹在两个工件中间,且与工件绝缘。当砂轮研磨工件表面,两片热电偶在工件表面的终点可焊接在一起作为一个节点。由于这个节点体积小,热容量足够小。如果放大和记录仪器的反应速度足够快,那么响应时间极短。真正的磨削温度可以精确地测量计算不通过进一步的演绎计算。2.2仪器图3显示了实验系统。工件的热电偶导线连接直流放大器,使信号放大100-1 000倍。这些信号由一个数字实时示波器进行分析,并由计算机记录。那一刻执行的磨削深度通过微进给系统保持在每步1微米,微进给系统是由我们自己的实验室制造的。进给原理如图3所示计算机提供精确的数字信号放大器。被放大的信号传输到一个压电晶体进行微进给。2.3实验条件标签1显示了圆盘砂轮的实验条件,而标签2杯形砂轮。标签1设备及圆盘砂轮表面磨削参数研磨机 赫兹- 63水平平面磨床砂轮 树脂结合剂金刚石外形:直板 300毫米25毫米240,W10工件单 晶硅25毫米10毫米5毫米磨削液 无标签2设备及杯形砂轮表面磨削参数车床 磨床CG6125A砂轮 树脂结合剂金刚石形状:杯形外径 100毫米内部直径 90毫米磨料尺寸 120,W28,W10工件 单晶硅25毫米10毫米5毫米磨削液 水基冷却液3实验结果3.1比较圆盘砂轮和杯型砂轮产生的表面磨削温度图4显示了实时记录圆盘砂轮硅片电热电压信号的波形直轮(W10)。磨削参数,磨削深度3微米,工作台速度20米/分,翻孔和干磨。该磨削电热电压脉冲,持续时间从快速上升到后来逐渐变为持续0.02至0.03秒,这一结果表明,高磨削温度变动对任何硅片只持续相当短的时间。快速的工作台使得圆盘磨削砂轮表面快速通过磨削工艺磨削区。细微的烧伤可在工件表面发现。图5显示了硅晶片的电热电压信号波形是根据杯形砂轮确定的(W28)。磨削参数如下:磨削深度为10微米,工作台进给速度为12毫米/分钟,冷却液占线。相较于图4,电热电压信号波形持续约12.5由上升至下降。显然,在磨削过程中杯形砂轮高温持续时间是一样长的圆盘砂轮的数百倍较.较长时间的持续高温,更会影响工件的质量。一个互补实验,其中条件类似图4,除了冷却液,从而进一步来证明上述结论。严重的结果出现了:极端高温,工件表面的裂缝,和工件与支撑之间的胶粘剂烧焦。这些实验结果表明,冷却液是必不可少在杯形砂轮磨削过程中,应采取一些适当的方法,如降低杯子的轮宽,选择一个合适的冷却液和砂轮修整的时间,以减少磨削热的产生。3.2圆盘砂轮在磨削过程中的实验现象和分析 表面磨削火花磨削温度进行了测试,观察期间的粉磨系统中的实际磨削深度逐渐减小到零弹性恢复过程中表面磨削温度的法律。在此研磨过程中,材料去除机理可能会有变化,有一些表面上的磨削温度的影响。图6显示了磨削温度,引发出次表面的关系。随着出火花次数的增加,表面磨削温度一步一步分解,最后到稳定状态。从实验结果,我们有下面的讨论。首先,在第六次出火花的研磨时间,表面磨削温度升高异常。类似的测试重复3次,以避免可能的错误。目前的测试显示在同一时间出现相近异常的结果。这可能由于一些因素,如热电偶节点异常接触造成的结果等等,我们将结果归结于材料去除机理的变化。当实际的火花磨削深度随着磨削次数减小,材料去除机理由韧性模式转向脆性模式。在这个过程中,磨削力和温度将有重大变化。研究结果还表示,该韧性模式已经与磨粒度没有密切关系。另外提供适当的条件,粗晶粒尺寸砂轮也可以实现韧性模式研磨。由于粗磨轮周围的磨粒比较少,所以使得粗磨轮表面的粗糙度比细磨粒的粗糙度大。其次,根据图6,表面磨削温度往往在第六个火花磨削加工后出现稳定值。这就是说,也许没有任何从工件表面被删除的材料。因此,存在一个时间限制火花硅片出磨。它是超过极限的,是无用的。最后,在第六次出火花的磨削工艺中,表面温度也可以进行测试,即使它实际上是毫无意义的。经测试温度保持不变,甚至对整个第六十次出火花磨削。研磨电热电压曲线测量图如图7所示。与图4的对比,显然,电热电压曲线这两种完全不同的。这一事实从一个放热峰的电压变化曲线为多峰表示,该磨削热是由单个颗粒产生。虽然,没有实际磨削深度,没有材料去除,砂轮和工件接触正在刨伤或刮伤的形式。还有磨削热转化成一定的能量。为了验证中的每个从单一的磨性多峰曲线结果高峰期,高峰之间的数量关系和工件工作台进给速度观察的假设,如图8所示。进给速度越快,则波峰数目越少。这是因为砂轮与工件之间的接触时间会随着进给速度增加而减少,所以,磨粒数导致研磨过程变短。有效磨粒数可以通过此方法可在火花磨削工艺中进行测量。33磨削粒度和磨削深度对表面磨削温度的影响3.3.1表面磨削温度由圆盘砂轮造成图9显示了表面磨削温度的硅晶片和磨削参数,包括晶粒尺寸,磨削深度,降低了磨磨直轮实验的关系。砂轮速度和进给速度依然能保持恒定,那里的砂轮速度为22.8米/秒,进给速度是8m/分钟。从图9在相同的磨削深度,表面研磨轮由细晶温度高于地面是由粗磨轮,其中在磨削力的相似关系是由其他学者观察。虽然磨床磨削深度增加温度升高面,提高率与颗粒大小不同。当磨削深度小于0.02毫米为240砂轮,磨削表面温度上升缓慢。当磨削深度超过0.03毫米,表面磨削温度急剧增加,导致烧伤的工件。作为一个磨(W10)轮,表面磨削温度迅速增长在磨削深度为0.005毫米,但是,当磨削深度为大于0.01毫米,研磨过程是不稳定的,表面磨削温度急剧增加,和工件烧伤被发现。3.3.2由杯形砂轮引起的表面磨削温度杯形砂轮速度和工件进给速度是恒定的。实验条件列于标签2。杯形砂轮的转速为1500r/ min时,工件进给速度为12毫米/分钟,磨削深度变动范围为从0.001毫米为0.01毫米。实验结果显示在图10中。在同样的圆盘砂轮磨削工艺过程中,磨削表面由细粒组成磨轮的温度明显高于由粗磨粒组成的磨轮。此外,冷却液对杯形砂轮在磨削过程中有着至关重要的影响。没有冷却液,磨削热将依然存在,并且在工件上积累,最后导致磨削过程的不稳定性和工件烧伤。4.结论1)由杯形砂轮磨削高温持续时间比圆盘砂轮磨削更长。冷却液在减少高温持续时间方面具有非常重要的作用。2)无论圆盘砂轮还是杯形砂轮,磨削面细颗粒温度比磨削面粗颗粒高。3)有效的火花研磨次数对于圆盘砂轮有一定限制。在有效的火花研磨次数之后,有一定的能量转换成磨削热,这个过程可以持续很长时间。4)这个实验装置和方法可以反映在与圆盘砂轮火花磨削过程中的有效的磨粒数量。
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