【作者】 高超；

【导师】 袁军堂；

【作者基本信息】 南京理工大学 ， 机械制造及其自动化， 2011， 博士

【摘要】 现代战争对特种车辆的机动性和防护能力提出了更高的要求,以工程陶瓷、纤维增强复合材料为核心的高性能复合构件具有密度低、防护性能好的特点,在特种车辆上有着广泛的应用前景。高性能复合构件在制作成型以后,需要根据现场装配要求进行二次加工,如钻削、铣削等。工程陶瓷以及纤维增强复合材料均为难加工材料,在制作形成复合构件后更是由于组份材料加工性能的迥异,使加工更加困难。论文通过理论分析及试验研究,对特种车辆高性能轻质复合构件的加工技术进行深入研究,为其推广和应用提供技术支撑。首先对复合构件的刀具研制及加工工艺进行了分析。针对陶瓷复合构件,从刀具材料、刀具结构、刀具制作工艺、金刚石参数设计等方面阐述了烧结、电镀、钎焊金刚石工具的研制过程；针对玻璃钢复合构件,研制了包括涂层TiN、多刃尖、S刃、PCD在内的多材料多刃型麻花钻头,同时,通过设计预紧力装置,优化构件加工顺序,选择冷却方式等提高了复合构件的加工质量。从理论分析和试验研究两个方面对复合构件的加工机理及刀具磨损进行了研究。采用压痕断裂力学模型及切削加工模型对装甲陶瓷的磨削机理进行了分析,建立了烧结金刚石钻头单颗磨粒的平均切削载荷及切削深度的计算公式；通过试验观察,进一步分析了装甲陶瓷的材料去除机理。结果表明：陶瓷材料的去除方式以脆性断裂去除为主,也存在部分塑性变形去除,是一种混合型的去除模式；对玻璃钢(GFRP)的磨削及切削表面的扫描电镜观察表明：玻璃钢的磨削加工是玻璃纤维在多磨粒多刃口作用下的剪切、弯曲及拉伸断裂,纤维断口可分为平滑断口、两平面及多平面断口、倾斜断口、多平面剪切断口、剥层断裂面断口五种形貌；切削加工是玻璃纤维在主切削刃作用下的剪切、弯曲、拉伸断裂,纤维断口可分平滑断口、弯曲断口、倾斜断口三种形貌；磨削表面和切削表面均由玻璃纤维和树脂涂附表面组成；分析了金刚石磨粒、烧结、电镀、钎焊金刚石工具及麻花钻头的磨损特征及机理。结果表明：金刚石磨损是切削力和切削热共同作用的结果；烧结金刚石钻头因内外径切削线上金刚石磨粒的的切削负荷不同,导致内喇叭状磨损变相；金刚石磨粒大量磨平磨钝导致钻头打滑；烧结金刚石钻头的胎体磨损成“流沙型”模式,而电镀、钎焊金刚石钻头的磨损未呈现“流沙型”特征；麻花钻因刀具材料不同及切削刃各点负荷不均匀,其中的高速钢以及S刃钻头主要为后刀面磨损,多刃尖钻头为刃尖磨损,PCD钻头磨损较为轻微。针对氧化铝陶瓷复合构件,从金刚石品级、结合剂设计两个方面,对烧结金刚石工具的胎体性能进行了优化,并结合正交试验,对工具的结构参数(粒度、浓度、水口数、壁厚)进行了优化；采用胎体性能优化后的金刚石钻铣刀对复合构件进行了铣削试验,分析了主轴转速、背吃刀量、进给速度对加工效率的影响；采用烧结、钎焊、电镀三种钻头对碳化硅装甲陶瓷进行加工,优选出适合的加工工工具,并通过单因素试验,分析了主轴转速及轴向力对加工效率的影响。结果表明：采用SMD40品级金刚石和结合剂Cu50Co25Sn18Ti7(wt%)胎体以及壁厚2.5mm、金刚石粒度35/40、浓度100%,水口数为3的金刚石薄壁钻头可以实现氧化铝陶瓷复合构件的高效率高质量孔加工；加工工艺参数对铣削效率影响大小的顺序为进给力、背吃刀量和主轴转速；电镀金刚石钻头在轴向力800N左右,主轴转速2600r/min左右,采用双面加工工艺可以实现碳化硅装甲陶瓷的高效率高质量孔加工针对玻璃钢复合构件,分析了预紧力、横刃、TiN涂层、直径对轴向力及分层的影响,建立了进给速度、主轴转速、钻头直径等因素对轴向力影响的经验公式;选用S刃TiN涂层钻头及PCD钻头,研究了其对轴向力及分层的影响,结合临界轴向力模型,确定了采用PCD钻头可以实现玻璃钢复合构件的高效率高质量孔加工对便携式孔加工设备进行了真空吸盘底座改进设计,并对底座吸盘密封材料及密封技术进行了研究；对真空吸盘密封结构进行了有限元接触分析,重点分析了橡胶硬度对接触的影响,并结合加工试验,对其可靠性进行了验证。结果表明：采用硬度HA=60的丁腈橡胶真空吸盘底座便携式孔加工设备,可以实现不破损待加工材料表面的孔加工,可靠性好,满足现场加工要求。更多还原

【Abstract】 Special vehicles have demanded higher mobility and barrier properties for the development of offense weapons in modern conflict. Since engineering ceramics and fibre reinforced composites are characterized of low density and excellent barrier propterties, high performance lightweight composite components made of them have wide application prospect. Usually, after the composite components are manufactured, secondary machining processes such as drilling, slotting are required for the purpose of joining and assembling. Engineering ceremics and fibre reinforced composite are belong to "difficult to cut" materials and the composite components made of the two will be more difficult to cut for their totally different machinability. The difficulty has limited their application. This paper is devoted to study intensive and systematical technologies to process the high performance composite components, which could provide technical supports for its broader application.Firstly, cutting tools and processing technology were analized. For the ceramic composite component, manufacturing technology of diamond tools including sintering, electroplating and brazing was analyzed; for the glass fiber reinforced plastics (GFRP) composite component, twist drills inculing TiN-coating, multi-edge tip, S-shaped tip and PCD types were used to conduct the experiments. By designing a pretightening force component, optimizing processing sequence of the ceramic composite component and adopting different coolling methods, machining quality of the composite components is improved.Secondly, machining mechanisms of the composite components and tool wear were studied. By using indentation fracture mechanics and ceramic cutting model, examining the ground surfaces by scanning electron microscope (SEM), the ceramic removal mechanisms, machined surface characteristics of GFRP and tool wear were analized. The results show that the ground surface of the armor ceramic consists of fractured area and ductile streak area, which indicate that the material removal modes include brittle fracture and ductile cutting, which is called "mixed removal modes", and the brittle fracture removal is much more prevalent; for the grinding process of GFRP, fibers are broken by shear behavior of abrasive grain and six type of broken morphology are found; for the cutting process, fibers are broken by shear behavior of the main edge of the twist drill and three type of broken morphology are found; Both the surface consist of glass firber aera and resin coated area; diamond wear is caused by cutting force and cutting heat; sintering bit converting phase is caused by the difference of cutting load working on the bit outside and inside diameters; sintering bit skidding results from diamond wearing smoothly; sintering tools form wear topography of " drifting sand " mode, which does not present in electroplating and brazing ones.Thirdly, experimental researches were conducted for the composite components. For the alumina composite component, with diamond SMD40 and matrix Cu50Co25Sn18Ti7(wt%) being adopted, the matrix performance was improved, then bit structure parameters were optimized by an orthogonal experiment. The results show that the bit with wall thickness of 2.5mm, diamond grain of 35/40, diamond concentration of 100% and 3 of the slots can obtain a high drilling efficiency. Milling tests were conducted by using the performance improved diamond tools and the main influcing factors to the efficiency were analized. The results show that the ascending order is feeding force, milling depth and spindle speed. For the silicon carbide ceramic, sintering, brazing and electroplating diamond bits were used to conduct drill tests, with the best performing bit being chosed, and by conducting single factor experiments, the influence of axial force and spindle speed to the efficiency was analized. The results show that electroplating bits present the best performance,800N and 2600r/min are not suitable to exceed under the experimental conditions, and two side drilling could obtain qualified holes.For the GFRP composite components, the influence of the pretightening force, chisel edge, TiN coat and drill diameter to the thrust force and delamination was analized, thrust force empirical equations of feed rate, spindle speed and drill diameter were built. S shaped tip drill with TiN coated and PCD drills were also used to analyze their influence to the thrust force and delamination; with critical thrust force model being built, conclusions were made that PCD drill could obtain the best drilling quality and the longest tool life among the drills.Finally, portable hole-drilling equipment of diamond drill machine was modified. A kind of vacuum base to the machine was designed. Seal material and sealing technology were studied; sealing property of the vacuum base was analized by finite element methods; drilling tests were conducted to verify the reliability of the modified equipment. The results show that with using the vacuum base (seal material, nitrile rubber, hardness HA 60), the Portable hole-drilling equipment is dependable, and could realize the spot process with no destroying surface of the composite component.更多还原