Gundrill life improvement for deep-hole drilling on manganese steel

Problems of heat dissipation and drill tip strengthening become intensified when deep-hole drilling on manganese steel, due to the higher cutting resistance and poorer heat conductivity of this material. The characteristics of manganese steel drilling are investigated and a novel drill point is developed. Industrial on-line tests, for drilling a slant oil hole on a crankshaft of manganese steel, confirm that drill life is improved by 33% in comparison with that of a conventional drill point.     

麻花钻几何参数对不锈钢钻削性能影响的研究

采用ProE和Deform-3D软件分析了影响麻花钻钻411性能关健的几何参数,主要研究麻花钻横刃和顶角对不锈钢钻削过程中切削力、扭矩、刀具磨损的影响.介绍了缩短横刃长度和采用S形横刃螺旋面钻尖对不锈钢钻削力和扭矩的影响.重点分析了顶角影响主切削刃的长度、单位刃长的切削负荷、切削层中切削宽度与切削厚度的比例、切削中轴向力与扭矩、切屑形成与排屑情况.对于在钻削中,如何提高钻头的寿命,提高钻削加工的生产率和孔的加工质量具有重要的指导意义.     

基于CFD-DEM的新型铝合金钻杆携岩仿真分析

由于川渝地区的地层结构较复杂,在钻探过程中产生的岩屑容易在井内沉积,使得岩屑运移难度大,最终还会造成卡钻与钻具断裂等重大井下事故。为了提高页岩气井的携岩能力,提出一种新型铝合金钻杆,对新型铝合金钻杆的携岩原理进行分析,得出该钻杆既可以提高岩屑运移能力,也可以降低摩阻,减少钻井液压耗,再对该钻杆进行力学分析与建模,利用实际参数计算,验证了钻杆的可浮性;然后对岩屑沉降与排出全过程进行分析,提出岩屑沉降与排出全过程的5个阶段;最后在充分考虑了钻井液、岩屑颗粒、钻杆和井壁相互作用的影响下,利用CFD-DEM耦合对新型铝合金钻杆的携岩过程进行精确仿真。改变钻井液排量、钻杆转速、岩屑粒径、钻杆偏心度,对新型铝合金钻杆的携岩能力进行分析,并将该钻杆的携岩效率与传统钢钻杆进行对比,研究了两种钻杆的岩屑运移率,最终得出新型铝合金钻杆相比传统钢钻杆具有更高的携岩效率。该研究成果对减少岩屑沉降、提高岩屑运移能力具有重要意义。     

Temperature Measurement of Cutting Edge in Drilling -Effect of Oil Mist-

In drilling, the temperature of the cutting edges of a drill is measured using a two-color pyrometer with an optical fiber. A cemented carbide drill with a diameter of 10 mm is used as a cutting tool, and carbon steel, cast iron and aluminum die-cast alloy are used as work materials. The temperature distribution along the cutting edge of a drill is measured and the influence of spindle speed and feed rate on the tool temperature is investigated. The maximum tool temperature is observed during the drilling of carbon steel. The effect of oil mist supplied from oil holes in the drill on the tool temperature is examined and the result is compared to that in turning and end milling. The temperature reduction in oil mist turning is approximately 5%, while in oil mist end milling it is 10-15% and that in oil mist drilling is 20-25% compared to the temperature in dry cutting.     

Experimental studies of step drills and establishment of empirical equations for the drilling process

Various sizes of step drills were manufactured by a CNC grinder machine and used in the drilling process with different speeds and feed rates to produce single step holes in S1214 free machining steel. The performance of step drills was compared with that of conventional twist drills in the drilling of the free machining steel for the same task. The influences of drill size, feed rate and cutting speed on the performance of step drills were studied. Experimental results show that for better cutting performance, the small diameter should not be less than 60% of the large diameter. Also, most of the changes in the characteristics of the thrust force were influenced by the smaller drill of the step drill. On the other hand, the small diameter part of the step drill only contributed about 30% of the torque. From the experimental results, empirical equations for drilling thrust force and torque have been established for step drills.     

The wear of WC-Co drill bits during rotary-percussive drilling of reinforced concrete

The wear mechanisms of WC-Co hardmetal drill bits during rotary-percussive drilling of reinforced concrete depend a number of factors such as the loading spectrum (thermo-mechanical stresses); workpiece material (type of concrete and reinforcement steel); hardmetal grade (WC-grainsize and Co-content); and drill bit geometry (design and location on the drill bit).Differences in wear mechanisms and wear intensity are evident, being highly dependent on the factors listed above. Additionally, the extreme conditions acting on the cutting edges during drilling of reinforcement steel (rebar) within the concrete induce significant microstructural and metallurgical changes within the near-surface regions of the drill bit.In this work, experimental studies have documented, analysed and quantified the active wear mechanisms in this complex and challenging application. A wide range of experimental variables have been investigated covering the large proportion of real-world cases encountered in the application of these drill bits on the construction site.     

新型铝合金钻杆对岩屑运移效率提升研究

设计一种新型铝合金钻杆。该钻杆可以悬浮在井眼上部,使高速区与岩屑床重合,提升岩屑运移效率。对新型铝合金钻杆进行载荷分析及各零件强度校核,验证新型钻杆的强度。在Fluent中,对环空井眼岩屑运移三维模型进行定性分析,对比不同钻杆转速、岩屑粒径、钻井液排量和钻井液密度下新型铝合金钻杆相对于传统钢钻杆岩屑运移的效率提升。结果表明：新型铝合金钻杆在不同条件下都有更好的携岩能力,特别是对于大粒径的岩屑运移有较大优势。研究结果有助于新型铝合金钻杆的使用和提升井眼清洁度。     

镶焊式金刚石取芯钻头的研制

提高金刚石取芯钻头寿命是提高整个矿产勘探效率的重要途径之一,特别是深孔钻探施工时,多采用高胎体金刚石取芯钻头。本实验首先利用热压法加工金刚石孕镶块,然后加工自带多层水口和水槽的新型钻头钢体,最后采用镶焊法将金刚石孕镶块与钻头钢体焊接在一起。试制的2只75/54.5mm金刚石取芯钻头,工作层高度达到22mm。野外实验证明:该钻头使用寿命分别达到86m和93m,比现场使用的普通金刚石取芯钻头,使用寿命分别提高120%和141%。     

石油钻杆刺穿失效原因分析

某石油钻杆在油田使用过程中发生早期刺穿失效。运用理化检测技术对失效的钻杆进行宏观形貌、化学成分、显微组织、力学性能分析和硬度测定。结果表明,钻井过程中在腐蚀介质的作用下,在钻杆内壁起刺处首先形成腐蚀坑,在复杂交变应力载荷作用下,钻杆表面腐蚀坑底部形成微裂纹并迅速扩展,最终导致钻杆发生腐蚀疲劳失效。为预防此类失效的发生,要严格控制钢管轧制工序,选用合适轧制工具尺寸,提高钢管内外壁表面质量,避免钻杆在油田使用时再次发生腐蚀疲劳失效。     

Taguchi optimization in drilling of AISI 316L stainless steel to minimize burr size using multi-performance objective based on membership function

Burr in drilling plays an important role on product quality and hence it is essential to minimize the burr size at the production stage. This paper presents the application of Taguchi optimization method for simultaneous minimization of burr height and burr thickness influenced by cutting conditions and drill geometry. The approach of Taguchi design for drilling optimization problem is based on multi-performance objective, which employs the membership functions. In the present work, optimal values of cutting speed, feed, point angle and lip clearance angle are determined for selected drill diameter values to minimize burr height and burr thickness during drilling of AISI 316L stainless steel workpieces. The effectiveness of the proposed approach is demonstrated through simulation results and experimental verifications.     

A study of high-performance plane rake faced twist drills.: Part I: Geometrical analysis and experimental investigation

A study of a modified drill point design with plane rake faces for drilling high-tensile steels is presented. A geometrical analysis has shown that the modified drill point design yields positive normal rake angle on the entire lips and point relieving in the vicinity of the chisel edge. This drill geometry can be expected to reduce the cutting forces and torque, and hence reduce the possible drill breakages when drilling high-tensile steels. An experimental study of drilling an ASSAB 4340 high-tensile steel with 7–13 mm titanium nitride (TiN) coated high-speed steel (HSS) drills has shown that the modified drills can reduce the thrust force by as much as 46.9%, as compared to the conventional twist drills under the corresponding cutting conditions, while the average reduction of torque is 13.2%. Drill-life tests have also been carried out and confirmed the superiority of the modified drills over the conventional twist drills. In some cases, the conventional drills were broken inside the workpiece, while the modified drills performed very well under the same cutting conditions. To mathematically predict the drilling performance and optimise the drilling process using the plane rake faced drills, predictive models for the cutting forces, torque and power will be developed in the second part of this investigation.     

Thrust force, torque, and tool wear in drilling the bulk metallic glass

The thrust force, torque, and tool wear in drilling of Zr-based bulk metallic glass (BMG) material are investigated. Drilling the BMG at high speed generates the chip light emission, high tool temperature, and severe tool wear. At low spindle speed, the BMG work-material builds up at the major and margin cutting edges and may break the drill. A range of feasible spindle speed and feed rate for the efficient drilling of BMG without the detrimental chip light emission and cutting edge work-material build-up has been identified in this study. Under the same drilling condition, the WC-Co tool generally requires less thrust force and about the same torque than the high-speed steel tool. The progressive wear of the major and margin cutting edges for BMG drilling is examined. Severe drill wear is associated with the bright BMG chip light emission. Without chip light emission, the drill wear is visible but not severe. This study concluded that precision holes in BMG could be generated with proper selection of tooling and process parameters.     

Effect of Immersion Time on the Mechanical Properties of S135 Drill Pipe Immersed in H2S Solution

During drilling process, if oil and gas overflow containing H₂S enters drilling fluids, the performance of drill pipes will decline significantly within a short time. In this paper, S135 drill pipe specimen was immersed in the saturated solution of H₂S at room temperature for 6, 12, 18, and 24 h, respectively. The tensile properties and impact properties of S135 drill pipe were determined before and after immersion for comparison. In addition, the S135 specimens were immersed for 3 days at 80 °C to determine the changes in fatigue performance. The test results indicated that the yield strength of S135 material fluctuated with immersion time increasing and the tensile strength slightly varied with immersion time. But the plasticity index of S135 decreased significantly with the increase in immersion time. The impact energy of S135 steel also fluctuated with the increase in immersion time. After 3-day immersion at 80 °C, the fatigue properties of S135 steel decreased, and fatigue life showed the one order of magnitude difference under the same stress conditions. Moreover, fatigue strength was also decreased by about 10%. The study can guide security management of S135 drill pipe under the working conditions with oil and gas overflow containing H₂S, reduce drilling tool failures, and provide technical support for drilling safety.     

基于声发射和振动信号的振动钻削钻头故障诊断试验研究

针对钻削过程中钻头状态监测问题,基于声发射采集系统和振动采集系统设计超声轴向振动钻削钻头故障监测装置,分别应用完整钻头和故障钻头进行45钢板的超声振动钻削对比试验,采集不同钻头状态的AE和振动信号,通过时域分析、频域分析和小波分解,分析故障钻头对AE和振动信号的影响。试验结果表明：通过AE和振动信号判别钻头状态,判别结果与实际一致,能够实现钻头的故障诊断。     

23CrNi3Mo钢钎尾端部崩落原因分析

为了提高 23CrNi3Mo钎具钢的凿岩疲劳寿命,采用光学显微镜、扫描电镜、硬度计等方法对不同疲劳寿命下的 23CrNi3Mo钢钎尾端部崩落的形貌、显微组织、晶粒度、硬度分布进行分析。结果表明：端部崩落程度与凿岩寿命有一定的对应关系,凿岩寿命越长,崩落越严重,崩落发生在渗碳层到基体的过渡层。崩落的原因是材料达到疲劳强度。端部奥氏体晶粒度越细,渗碳后硬度高,凿岩寿命延长。     

硬质涂层的微磨粒磨损评价方法

微磨粒磨损试验是最近发展起来的评价涂层耐磨性的方法。比较了通过微磨粒磨损试验和球（销）盘磨损试验评价硬质涂层耐磨性的差别,论述了涂层耐磨性评定结果与涂层零件使用性能之间的关系。被测试的涂层为CrN和CrSiN,工件为高速钢钻头。研究结果表明,用微磨粒磨损试验测得的微粒磨损系数（ka）与镀层钻头的钻孔寿命之间存在一定关系,也即当后。小于某一数值时,镀层钻头的钻孔寿命较高。而用球（销）盘磨损试验法测定的比磨损率则与钻头的钻孔寿命无内在联系。     

45钢超声振动钻削加工机理及其试验研究

通过超声振动加工技术对45钢进行钻削加工试验,研究超声振动加工技术的钻削机理、加工孔的表面微观形貌、切屑形态,以及超声振幅和主轴转速对加工孔表面粗糙度的影响规律。结果表明:在普通车床CA6140上利用超声振动发生器、换能器、变幅杆连接钻头对45钢进行钻削,可实现传统钻削加工与超声振动钻削加工的良好结合,有效改善孔内表面的形貌,降低表面粗糙度值,且切屑形态规整;同时,超声振幅控制在20μm最佳,主轴转速在320~400 r/min范围内的加工效果较好。     

和田青玉超声波深孔高速钢麻花钻钻削试验研究

基于和田玉特殊的物理性能,采用直径为2、1.5、1 mm的高速钢麻花钻,在其主轴转速为700、1500、1800r/min;进给量为3μm/r和5μm/r的情况下;分别进行附加超声波振动和不附加超声波振动加工试验;在钻削加工过程刀具磨损,扩孔量、孔内表面粗糙度三个方面进行对比分析,超声振动波钻削能获得更好的加工质量和效率,并能减少钻头的磨损和破坏,为和田玉精密加工提供了一种新的深孔加工工艺方法。     

小孔导电加热钻削钻头后刀面磨损及孔表面质量研究

难加工材料的小孔钻削加工严重地磨损钻头的后刀面,而后刀面的磨损是麻花钻磨损的主要形式。针对难加工材料不锈钢板采用导电加热钻削小孔进行试验,定量地分析了进给量、加热电流以及切削速度等参数与麻花钻后刀面磨损程度之间的关系,并研究了该磨损量对孔壁表面粗糙度的影响趋势。     

基于回归正交试验的浅孔钻钻削的有限元仿真

基于回归正交试验法设计钻削模拟方案,利用最小二乘法原理得到钻削力的经验公式;基于有限元软件Deform3D平台,建立了用浅孔钻钻削加工45钢的有限元模型,动态模拟浅孔钻钻削过程,获得了浅孔钻钻削加工过程中工件的等效应力和温度,分析预测了加工过程中硬质合金刀具所受的主切削力、径向力以及两刀片所受的扭矩,并评估刀片的磨损情况。