【作者】 张辽远；

【导师】 贾春德；

【作者基本信息】 长春理工大学 ， 机械制造及其自动化， 2007， 博士

【摘要】 随着科研和工业技术的迅速发展，硬脆材料在各个领域的应用已经日益普遍。这些硬脆材料，如硅单晶、石英晶体、陶瓷、宝石、玻璃、稀土磁性材料、半导体材料、硬质合金等。金刚石线锯在硬脆材料的加工方面逐渐显现出一系列无可比拟的优点：加工表面损伤小、挠曲变形小、切片薄、片厚一致性好、能切割大尺寸硅锭、省材料、效益好、产量大、效率高等，是一种相对较新的技术，在近十几年来得到了快速发展。本文提出了电镀金刚石线锯超声波切割技术完全具有自主知识产权的切割方法。该研究课题具有较大的研究价值和实际应用意义。研究内容包括：①研制一台电镀金刚石线锯超声波切割实验装置；②研制适合超声振动条件下的电镀金刚石线锯；③对电镀金刚石线锯和磨粒进行运动和动力学分析，研究电镀金刚石线锯的加工轨迹；④对电镀金刚石线锯超声振动锯切有关的工艺参数与材料去除率、锯切力、表面质量等方面进行系统的实验研究；⑤对电镀金刚石线锯的超声锯切时线锯的失效形式及机理进行了实验研究与分析；⑥最后通过研究电镀金刚石线锯超声锯切过程的分析，从断裂力学和锯切力的角度分析研究材料去除机理。该项技术与传统的硬脆材料切割方法不同，通过研制电镀金刚石线锯超声波切割实验装置验证了该项技术的原理是可行的。与有关单位合作，采用自制的电镀设备及工装进行了线锯的电镀工艺研究，并制造出了质量稳定的电镀金刚石线锯，镀层和基体结合牢固，镀层对金刚石颗粒的把持良好，金刚石颗粒分布均匀，达到该项技术条件的使用要求。通过对该实验装置中的关键技术研究，设计制造了超声电源、换能器、变幅杆等。该实验装置的主要技术参数是：超声发生器的功率为250W(可调)，频率为20KHz，工具的最大振幅为20μm。对电镀金刚石线锯超声振动锯切工艺进行了深入研究，实验结果表明该方法的材料去除率可达25mm/min以上，大大高于相同条件的往复式线锯，是其材料去除率2.5～3倍，能充分发挥金刚石的卓越性能。在此基础上进一步研究了金刚石粒度、侧向压力、线锯速度以及工件材料性质对锯切过程的影响。通过正交试验对锯切工艺参数进行了优化。优化实验表明：要获得较高的锯切效率，较好的质量和最优的经济性，其最佳的工艺参数为：金刚石粒度为180~#，侧向压力为12N，线锯往复速度为300rpm，锯切效率最高。其加工零件的表面粗糙度为Ra0.7～0.8μm，比相同条件下的往复式线锯(Ra1.3～1.5μm)提高近1倍。经过对电镀金刚石线锯和磨粒进行了运动和动力学分析，作者认为在锯切过程中磨粒在去除过程中与工件的接触是非连续状态的，其实际接触时间只占整个工作周期的1/3～1/5，试验结果和理论分析都证明其总的平均锯切力小、锯切温度要降低，而且局部产生的应力也有充足的释放时间和条件。通过对电镀金刚石线锯实验和分析，作者认为金刚石线锯的失效形式主要有：金刚石颗粒的磨损、破碎和脱落等。在超声振动切割时，金刚石颗粒受到的冲击作用，由线锯的柔性而得到一定程度缓解，一般不会因机械冲击而产生破碎或脱落，主要表现为抛光磨平。在较低锯切速度下，由于锯切力较大，金刚石颗粒将产生破碎和脱落。金刚石颗粒首先在较小的应力和锯切热的作用下，在尖角和棱边处产生抛光磨平或轻微的局部破碎，随着磨平和局部破碎的不断增加，金刚石承载能力下降，部分金刚石颗粒将产生整体破碎。摩擦产生大量的锯切热，使镀层软化，降低镍镀层对金刚石颗粒的把持力，在机械冲击的作用下，金刚石颗粒会产生整体脱落现象。当参数选择不当，线锯的寿命会大大降低甚至会发生断裂。通过对金刚石线锯锯切力的理论研究，建立了线锯切割时锯切力的理论模型。该模型在分析单颗粒金刚石的锯切力的基础上，综合考虑了线锯速度、工件进给速度、线锯参数和工件性质对锯切力的影响。研究结果表明：金刚石线锯的锯切力与工件材料的厚度和工件进给速度成正比和线锯速度成反比，并且和材料性质有关。在研究分析已有的硬脆材料去除机理的基础上，提出了电镀金刚石线锯超声锯切机理的模型，根据压痕模型，认为电镀金刚石线锯超声锯切过程中的材料去除的主要原因是由赫兹碎裂(Hertzian Fracture)引起的。假如工件材料的表面被一个滑动的压头弹性地压下，则在压头滑移轨迹后面的材料中产生张应力场，当其值超过临界的正常负荷时，就会产生局部圆锥形裂纹，这个负荷比使材料表面形成永久刻痕所必需的力要小得多，这说明在较低的压力下硬脆材料仍可被破碎。在此基础上分析了电镀金刚石线锯超声锯切去除材料中，除常规的锯切过程外还包括压缩状态下的裂纹扩展、拉伸状态下的裂纹扩展、空化状态下的裂纹扩展、在锤击、冲击和滚动切削作用下裂纹的扩展等。而裂纹在形成、扩展、闭合过程中，在纵向和横向是不同的，纵向裂纹的尺寸要大于横向裂纹，而横向裂纹尺寸是形成工件表面粗糙度的主要因素。更多还原

【Abstract】 Along with the rapid development of scientific research and industrial technology the application of hard and brittle material in all kinds of field become more and more popularize. These hard and brittle material including silicon crystal, quartz crystal, ceramics, gem, glass, rare-earth element and magnetic material, semiconductor material, hard alloy etc. In a great deal application of industry they required to machining geometry shape some of them required high precision.In the machining of hard and brittle material diamond wire saw has some unexampled adventures: small damage of machining surface, small deflection deformed, thin cutting slices, good identical of thickness dimension, can cutting big silicon, save material, good efficiency, big output, high efficiency etc. This is a new technology has great development during these years.A cutting method of electroplated diamond wire saw with ultrasonic vibration has self knowledge property right was reported in this paper. This subject has great research worth and factual application. The research contents include: the design and manufacture of experiment setup, this setup fulfilled the basic requires of experiment, the design and manufacture of the electroplated diamond wire saw fit for ultrasonic vibration. Has done motion and dynamics analysis and has developed the machining locus of electroplated diamond wire saw. The experiment research on technological parameter, remove rate, cutting force, surface qualities etc about electroplated diamond wire saw were carried out systematically. The research and analysis were carried on lose efficacy and mechanism. At the end the lose theory was carried on the theory analysis of fracture mechanics and cutting force through the analysis of electroplated diamond wire saw cutting process.A new cutting technology- electroplated diamond wire saw with ultrasonic vibration cutting technology was first research and development. This technology was different from former hard and brittle material cutting method, the principle was validated feasible through the design and manufacture experiment setup for electroplated diamond wire saw with ultrasonic vibration. Cooperate with other associate unites, research on electroplate techniques was done through homemade electroplate device ,manufacture stable quality electroplated diamond wire saw , strong combination of electro paint and body, good keep of electro paint to diamond grain, equality distributing of diamond grain, reach the use request of this technology. Design and manufacture ultrasonic power source, transducer, amplitude etc through the research of the key technology. Ultrasonic generator power is 250W (adjusting), frequency is 20 KHz; maximal swing of tool is 20μm.The experiment indicates this system has stable and credible work.Through lucubrate of electroplated diamond wire saw with ultrasonic vibration technique, experiment result indicates use this method remove rate exceeds 25mm/min is 2.5～3 times of the same condition of come and back wire saw, the adventure property of diamond was full exerted. The influences of the work piece nature were taken into account based on diamond grain, side force, and wire saw speed. The cutting techniques parameter was optimize on orthodox test. In order to ensure high cutting rate the best technique parameter: diamond grain is 180~#,side force is 12N,wire speed is 300rpm.The work piece surface roughness is Ra0.7～0.8μm has increase 1 time over come and back wire saw.The author considers during the cutting process the contact of grain and work piece is not continuous, the factual work time is 1/3～1/5 of the vibration cycle so the average cutting force and temperature is decrease, has the time and condition to release the force of the part generate and develop electroplated diamond wire saw cutting track were based on the motion and dynamics analysis of electroplated diamond wire saw and grain.The main failure forms are diamond grain abrasion, crash, brushing off based on lucubrate of electroplated diamond wire saw and mechanism. During the high speed cutting the impact of diamond grain lightened because of wire saw flexible,generally the main behavior is polishing rubdown do not engender crash and brushing off of machine impact. During low cutting speed, the diamond grain will crash and brushing off because of big cutting force. First the diamond grain get little stress and caloric in the sharp-angled and arras engender polishing rubdown or light local crash, along with increase of rubdown and local crash the carrying capacity decline some diamond grain engender whole crash. Diamond grain get machine impact engender whole crash because of friction engender great cutting heat make electro paint intenerate, decrease nickel-plate’s hold of diamond grain .If parameter choose improper the life of wire saw will decrease even more parted.Cutting force theory model was made based on theory research of diamond wire saw cutting force .This model taking into account cutting speed, feed rate, wire saw parameter and work piece property to cutting force based on one grain cutting force. Research show that diamond wire saw direct ratio to the thickness and feed rate of work piece, inverse to wire saw cutting speed, and has something with material property. Electroplated diamond wire saw with ultrasonic vibration theory model was advanced based on research and analysis of the hard and brittle material lose theory, considers the main lose method of electroplated diamond wire saw with ultrasonic vibration cutting was Hertzian Fracture. If work piece surface was stretch pressed by a slip press head then after press head slippage locus material engender tensile stress field, when over critical usual burden will engender local taper crack .This burden less than the force make material surface engender permanent snick. This shows that in lower press hard brittle material still crashed. On this basis analyzed during electroplated diamond wire saw with ultrasonic vibration cutting including crack expand of compress condition, crack expand of extend condition, crack expand of cavitations condition and crack expand of hammer attack, impact and scroll cutting besides usual cutting. During the crack form, expand, close process upright and landscape orientation is different, upright crack dimension bigger than landscape orientation crack dimension and that landscape orientation crack dimension is the main factor of form the work piece roughness.更多还原