正偏压对微波等离子体CVD法制备金刚石薄膜的影响

线形同轴耦合式微波等离子体CVD法是在硬质合金微型钻头(微钻)表面沉积金刚石涂层的最佳方法之一.本文首先研究了酸碱两步预处理后微钻表面的形貌和成分,然后研究了微钻工作表面金刚石的沉积情况,最后重点研究了正偏压对微钻不同位置金刚石生长的影响.结果表明,在微钻上施加50 V正偏压时,金刚石薄膜具有最佳的形貌和较好的均匀性.     

电路板复合材料高速钻削刀具的磨损

讨论印刷电路板(PCB)复合材料高速钻削刀具的磨损机制,分析PCB高速钻削刀具的磨损形态,总结PCB微钻材料的发展.提出PCB高速微钻刀具材料选择的基本要求.目的是延长PCB刀具寿命,提高PCB高速微钻孔质量.     

CVD金刚石强化孕镶金刚石钻头的冲击回转钻进试验研究

孕镶金刚石钻头的性能对地质勘探钻进的效率和成本有很大的影响.为了提高钻头的性能,本文设计、制造了一种用CVD金刚石条作为硬支点材料的新型孕镶金刚石钻头.设计了CVD金刚石务的尺寸、数量及在钻头胎体上的排列方式.根据被钻岩样的可钻性及研磨性,设计了钻头胎体硬度、金刚石粒度、浓度及钻头结构.采用中频感应热压法制造了φ59 ...     

印制电路板用微钻结构的优化设计

印制电路板材机械钻孔加工对硬质合金微钻要求极高,目前硬质合金微钻结构设计局限于螺旋角、芯厚、顶角、沟幅比、硬质合金晶粒度、晶粒结构等优化手段,印制电路板机械钻孔领域对提高硬质合金微钻的加工时孔位精度已经面临瓶颈。本研究设计了一种区别于传统双螺旋槽微钻的新型微钻结构,包含了短排屑槽、长排屑槽及连通槽将长短排屑槽连通设计。该设计在保证了硬质合金微钻正常切削性能和孔位精度的同时,提高了硬质合金微钻的钻体刚度。利用ANSYS有限元分析,在相同切削力加载情况下,新结构硬质合金微钻钻削时钻尖的径向位移量明显减小。经钻削实验验证,该新型微钻相较于传统硬质合金微钻钻削印制电路板背面孔位精度CPK值可提高1倍。     

PDC实钻性能的测试与评价

在总结分析国内外有关PDC切削齿性能测试方法的基础上,采用常规检测方法对不同生产厂家的5种PDC产品的磨耗比、冲击韧性和热稳定性进行测试、评价和优选,并对优选出的2种PDC在微钻试验平台上进行实钻性能测试。结果表明:用微钻试验的钻进效率衰减系数和钻进效率均峰值来评价PDC实钻性能,方法科学,数据准确,结果实用,可作为煤矿用PDC钻头切削齿选型的参考依据。      

闭合场非平衡磁控溅射离子CrAlTiN镀层在PCB用微钻中的应用

采用闭合场非平衡磁控溅射离子镀技术在PCB微钻上进行复合金属镀层处理,通过与无镀层微钻进行钻削试验对比,结果表明:CrAlTiN镀层微钻使用寿命与无镀层微钻相比,寿命可提高3倍;具有纳米结构的高硬度镀层显著提高了微钻的耐磨性.     

高性能涂层微钻在IC封装基板精密微孔加工应用研究

研究微钻不同涂层种类对IC封装基板加工性能及效率的影响。针对几种典型难加工IC封装基板，通过对IC封装基板机械钻孔加工难点、刀具失效机理、不同高性能涂层微钻的性能特点进行分析，设计不同高性能涂层微钻，获得了IC封装基板尤其是难加工封装基板的钻孔品质保障、效率提升、刀具寿命提高方面的有效解决方案。研究结果显示，针对刀具磨损极大的高填料封装基板，金刚石涂层可有效改善微钻的耐磨性能，相对于未涂层微钻和其他类型涂层微钻，刀具寿命显著提升。类金刚石涂层因其较低摩擦系数，有利于切屑的快速排出、降低了加工温度和减小了切削力。对厚径比大、排尘困难的封装基板，如FC-BGA用厚芯板的微孔加工，能有效改善孔壁粗糙度，提升孔位精度，降低断刀率，大幅提升钻孔品质；对于较薄的封装基板如CSP板的微孔加工，能够降低断刀率、增加叠板数量，提升加工效率。     

关于岩石分级问题

根据冶金部科技司的要求,我们开展了岩石分级的研究工作。三年来在矿山领导、工人和技术人员的大力支持下,以全国矿山为主,先后调查了15个省市44个单位,实测了28个矿山和工地的岩石可钻性指标,并收集了267个岩石标本,进行了有关力学指标试验,初步掌握了矿山穿凿工程的岩石可钻性分级情况,验证了所推荐的岩石可钻性分级的方案。     

小直径钻头（微钻）的正确使用

直径小于3．175mm的钻头，通常称为微钻。要使微钻在使用中发挥高效率，必须考虑一系列因素：如钻头本身的各项要素、加工参数、孔深、安装的完善性及工件的结构等。要把这些相互影响又对钻削过程十分敏感的因素处理好，需要有科学的创新精神。     

微细钻铣刀具表面涂层制备及应用研究进展(Ⅱ)

随着产品高度集成小型化,切削尺寸逐渐减小,微切削技术受到了国内外越来越多的关注。本文从印制电路板、钛合金、铝合金、镍基合金、淬硬钢等难加工材料出发,综述了各种难加工材料微细钻铣加工存在的难题。从切削力、刀具磨损、表面粗糙度、微细毛刺、表面加工硬化等方面进行讨论,介绍了针对难加工材料微细钻铣削常用的涂层种类,归纳了影响涂层微钻铣刀切削质量的相关因素,包括材料粘附性、切削力波动、磨粒磨损等。总结了各种难加工材料适用的微细钻铣刀具涂层,并提出一些改善涂层微钻铣刀具切削质量的方法及建议。综合经济性、材料加工适应性原则,开发出最佳涂层微细钻铣刀具,不断地提高微切削的质量,对微小零部件、微电子产品的发展具有重要意义。     

A NEW METHOD FOR CLASSIFICATION OF ROCK DRILLABILITY

A New method of rock drillability classification for impregnated diamond drilling is recommended. The essence of the method is comparing the area of the slots cut respectively on a standard synthetic rock sample and the rock sample being classified by one diamond saw to determine the rock drillability in diamond core drilling. This method has the advantages of good in simulation and stable in comparison standard.     

Sequential laser and mechanical micro-drilling of Ni superalloy for aerospace application

Laser percussion drilling is inherently associated with poor geometry and thermal defects. While mechanical micro-drilling produces good quality holes, premature drill breakage often occurs and it is difficult to drill holes at acute angles. This paper presents the feasibility and basic characteristics of a new approach for micro-drilling In718 alloy sheets at an acute angle, using sequential laser and mechanical drilling. The results demonstrate that sequential laser-mechanical micro-drilling alleviates the defects associated with laser-drilled holes, reduces burr size and machining time and increases the tool life compared with mechanical drilling.     

Micro-drilling of alumina green bodies with diamond grit abrasive micro-drills

Since ceramic plates containing many micro-holes are used for MCPs (Micro-channel plates) for electron amplification, catalytic converters, filters, electrical insulators and thermal conductors in integrated circuits, the efficient drilling of micro-holes in ceramic plates is important for productivity and cost. Since ceramics have poor machinability due to their low thermal conductivity, high hardness and high brittleness, in this work, alumina green bodies rather than sintered alumina were drilled to manufacture ceramic MCPs, followed by sintering the machined green bodies. Alumina green bodies were drilled with electro-deposited diamond grit WC micro-drills, and the cutting force with respect to drilling time was measured to determine a suitable micro-drilling condition. From the measurement of the micro-drill tip wear during micro-drilling of alumina green bodies, a model for the cutting force during micro-drilling was constructed.     

人造单晶金刚石激光微孔加工技术研究

人造单晶金刚石传统的激光打孔方法采用"轮廓法".该方法的缺点是越靠近孔的中心剥去的材料越多,精确的孔型难以得到.本文在理论和实践的基础上,提出了一种新的激光数控打孔自适应模型.在模具的压缩区,通过控制工件的转速实现材料的均匀去除,并且使激光脉冲能量随着孔径的减小而递减,以提高孔型精度.结果表明,该模型可以有效提高微孔的加工精度,最小加工孔径达到3.5 μm.理论和实践证明,本文提出的激光打孔数控模型是人造单晶金刚石激光打孔的有效方法.     

Experimental characterization of micro-drilling process using nanofluid minimum quantity lubrication

This paper discusses the experimental characterization of the micro-drilling process with the nanofluid minimum quantity lubrication (MQL). The miniaturized drilling machine tool system is developed, and then a series of micro-drilling experiments are conducted in the cases of compressed air lubrication, pure MQL and nanofluid MQL. For the nanofluid MQL, nano-diamond particles having the diameter of 30 nm are used with the base fluids of paraffin and vegetable oils. For the micro-drilling process, an uncoated carbide twist drill having the diameter of 200 μm is used for making holes in the aluminum 6061 workpiece. The experimental results show that the nanofluid MQL significantly increases the number of drilled holes and reduces the drilling torques and thrust forces. In addition, the nanofluid MQL effectively eliminates remaining chips and burrs to enhance the quality of drilled holes.     

Tool life improvement by peck drilling and thrust force monitoring during deep-micro-hole drilling of steel

An unstable drilling process results from the insufficient supply of cutting fluid and bad chip removal as machining depth increases. These causes of unstable drilling lead to serious problems in micro-drilling. All drills were broken while drilling the first hole in the micro-deep-hole drilling of steel with an aspect ratio over 10, regardless of the cutting conditions. Peck drilling, which utilizes an intermittent feed, is widely used in drilling deep holes. Generally, the one-step feed-length (OSFL) of peck drilling is one and a half times longer than the drill diameter in conventional drilling. An OSFL between one half and twice the micro-drill diameter was used by some workers for micro-drilling. However, this range of OSFL was an arbitrary decision. This paper proposes the peck drilling method using thrust force signal monitoring. The monitoring parameters for peck drilling (MPPDs) are introduced through the analysis of thrust force in both the time and frequency domain. The monitoring system was embodied using LabVIEW. Through this monitoring system, the proper OSFL for stable machining in the deep-micro-hole drilling of steel was determined to be about a tenth of the tool diameter.     

Forces exerted on the tool-electrode during constant-feed glass micro-drilling by spark assisted chemical engraving

The forces exerted on the tool-electrode during Spark Assisted Chemical Engraving (SACE) constant velocity-feed glass micro-drilling are measured for different machining voltages, tool feed-rates and tool sizes. A diagram of the force regions in the hole-depth vs. tool feed-rate plane is constructed for different voltages and tool sizes. Two rate limiting steps for micro-drilling were identified. For low depths, the rate limiting step is the work-piece surface heating while for high depths it is the electrolyte flushing. Based on these findings, the tool feed-rate vs. hole-depth plane of the force regions was normalized using the time needed to heat the local glass surface and the tool radius. A correlation between the force occurrence and the current signal is identified where the current shifts upwards by a constant value when a force is exerted on the tool. This finding allows the usage of the current signal to detect the contact between the tool and the glass surface. The measurement and understanding of the forces exerted on the tool-electrode that this work brings is a first step towards the development of force feed-back algorithms for SACE machining.     

孕镶金刚石钻头破碎花岗岩岩屑粒径分布研究

收集微钻实验过程中孕镶金刚石钻头破碎花岗岩所产生的岩屑,分析其粒径分布,定量研究金刚石参数、钻进参数对岩屑粒径分布的影响。结果表明:岩屑粒径在一定范围内呈单峰值分布,粒径尺寸集中分布在40～100 μm,粒径分布基本符合对数正态分布规律;金刚石粒度、浓度,钻压和转速对岩屑的粒径分布有较大的影响。      

面向异型石材加工的开放式数控系统开发

本文简要介绍了开放式数控系统的特点，构造了基于开放式标准的石材加工业数控系统的软硬件基本结构。在此基础上，采用面向对象的方法开发了异型石材加工数控系统的自动编程模块。开发的基本原则是系统的开放性与可扩充性。     

Modeling surface roughness in the stone polishing process

In this paper, a new method for modeling and predicting the surface roughness of the workpiece in the stone polishing process is developed. This method is based on the random distribution of the stone grain protrusion heights and the force balance by contact grains. To do so, first, the topography of a polishing stone is generated based on a Gaussian distribution with the mean value and standard deviation determined from a given stone grit number. Second, the plasticity theory is applied to determine the micro depth of cut of a single grain for a given workpiece hardness (Brinell number). Third, a search method is developed to determine the number of the contact grains and the micro depth of cut, based on the force balance principle between the force applied on the stone and the forces transmitted to the grains that are in contact with the workpiece. Fourth, a method is presented for predicting the surface roughness based on the micro depth of cut and contact grains. A good agreement of the prediction results with the experimental data proves the effectiveness of the proposed method.