Investigation of wear resistance of drill bits with WC,Diamond-DLC,and TiAlSi coatings with respect to mechanical properties of rock

Drilling is an important engineering operation with extensive application in many fields of industry including mining engineering, oil and gas exploration and exploitation, civil engineering, groundwater management, etc. Drill bits must be able to endure enormous stresses that gradually wear them down during the drilling operation. In rock drilling, wear resistance is a key determinant of the drill bit lifetime and hence the drilling cost, thus basically affecting the choice of drilling method for any given rock type. With the advent of new wear-resistant materials, they can be used to improve the resistance of drill bits against wear and erosion. This study investigated the wear resistance of drill bits with tungsten carbide (WC) coating, DLC-Diamond coating, and titanium-silica‑aluminum (TiAlSi) coating when drilling in three types of hard rock, namely Khoshtinat Granite (A₁), White Natanz Granite (A₂) and Nehbandan Granite (A₃). The drilling tests were performed on cuboid specimens using a drilling machine at rotation speeds of 850, 900 and 950 rpm and penetration rates of 12, 18 and 24 mm/min. The results showed that for any fixed drilling conditions, the wear rates of the TiAlSi drill bit in A₁, A₂, and A₃ were respectively 48%, 52%, and 60% lower than those of the WC drill bit. In the same rocks, the Diamond-DLC drill bit also showed 42%, 44.25%, and 55% lower wear rates than the WC drill bit. in addition to the observed changes in wear rate of the drill bits, the surface roughness created by these drills represents the optimum performance of the TiAlSi drill bit. It was observed that, as the mechanical properties of the rock (uniaxial compressive strength, Mohs hardness, Schimazek's abrasivity index and Young's Modulus) increased, the tested drill bits showed wider differences in terms of wear resistance. As the TiAlSi drill bit had the lowest wear rate (27%) and after that, the Diamond-DLC drill bit showed a better wear (30%) performance than the WC drill bit (60%).     

Examination of wear damage to rock-mining hardmetal drill bits

WC/Co mining bits from a drill head used for drilling holes for roof support bolts in a mine were examined using a focused ion beam scanning electron microscope (FIB-SEM). This was combined with energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) analyses to study the chemical interaction between the drill bit and the rock. It was found that at the surface of the buttons there was depletion of cobalt, change in chemistry of the remaining binder regions, and changes to the morphology of the WC grains. Tribochemistry calculations were done to understand the possible formation of silicides at the surface of the drill bits, and thus emphasise the importance of quartz content in rock on wear. The evidence of mechanical damage combined with chemical reactions is another step towards understanding the complete wear process in hardmetal mining tools.     

Near-surface phenomena occurring in cemented carbides with different binders during rotary-percussive drilling of reinforced concrete: FE simulation and microstructural investigations

Rotary-percussive drilling through steel rebar in reinforced concrete subjects drill bits to intensive thermomechanical loading and wear. Significant microstructural changes occur in near-surface regions. These include, but are not limited to, micro- and mesoscopic cracking; fracture at WC-binder interfaces; WC comminution; partial WC dissolution and rearrangement; surface decarburization; binder depletion and pore formation; and the creation of secondary phases within the binder [1–4].Cemented carbide drill bits with three different binders (Co, CoNi and Ni) were drilled in steel reinforced concrete. After sectioning the drill bits, numerous analysis methods were employed to identify the type and composition of phases present; to characterize microstructural changes and wear phenomena; and to locally measure the properties of the modified surface microstructure. Noticeable differences between the binder types are evident.A variety of finite element (FE) simulation methods were used to describe the thermo-mechanical loading spectrum acting on the drill bits. Transient (dynamic) impact loading and quasi-static indentation simulations calculated the stresses and temperatures generated in the application. The magnitude, orientation vectors and spatial distribution of the simulated stress and temperature fields were correlated with the experimental findings regarding crack initiation sites and regions experiencing thermo-mechanically induced surface microstructural and compositional modification. This paper presents some of these findings from extensive experimental and simulation studies.     

孔底流场和温度场数值模拟与试验研究——以取心孕镶金刚石钻头为例

为提高金刚石钻头的钻进效率,采用数值模拟与试验的方法研究孕镶金刚石钻头孔底流场与温度场,以合理设计钻头结构,保证钻进过程中钻头具有良好的冷却和排屑能力,避免钻头底唇面温度上升过高造成其非正常磨损。结果表明:流场产生的横向压力对转向面水口壁的压力破坏作用较大;钻头与岩石接触面温度变化与水口数目有关,水口过多会导致单个水口的钻井液流量减少,降低水口处的热传导效率,冷却效果不足,从而造成钻头磨损。      

有序排布热压孕镶金刚石钻头的性能研究

用点胶-热压法制备了有序排布孕镶金刚石钻头,并用形貌仪观测了钻头的表面形态以及通过室内钻进实验研究其钻进性能。结果表明:在进尺数相同的情况下,有序排布钻头的钻进效率比随机排布钻头高出23%,有序排布钻头的金刚石颗粒出刃高度比随机排布钻头高出1倍;而且有序排布钻头的胎体磨损呈有利于金刚石颗粒自锐的蝌蚪状。有序排布的钻头金刚石表面出现微破碎,与随机排布钻头的2种金刚石极端磨损形貌相比,在钻进过程中优势明显。      

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%。     

煤矿井下随钻测量定向钻进用PDC钻头的研制

煤矿井下随钻测量定向钻进需要设计高品质的PDC钻头。本论文从PDC钻头的结构参数到PDC切削齿的选型均进行了较深入的分析研究;同时研制了96 mm胎体式定向钻进用PDC钻头,并进行了现场试验,共钻进1个主孔和4个分支孔,平均钻进时效为4.12 m/h,累计进尺达1 001.6 m。试验结果表明,该钻头造斜效果好,使用寿命长,完全能满足使用要求。     

提高金刚石钻头耐磨性和降低烧结温度的试验研究

目前，大多数金刚石钻头采用粉末冶金热压疗法烧结，热压法普遍存在烧结温度较高，对金刚石的原始强度产生不利的影响，也直接影响钻头的质量。同时，胎体配方还比较单一．钻头的耐磨性能不理想，在强研磨性岩层或破碎岩层中钻进寿命较低：这两方面的问题有待进一步研究解决。本文针对这两个问题，采用正交设计方法，在胎体材料中通过加入磷与硼元素，进行了有益的试验研究。结果表明：烧结温度有所下降，钻头的性能有了提高。     

适合吐哈油田西山窑地层的PDC钻头提速研究

吐哈油田西山窑地层具有高硬度、研磨性强等特点。该地层采用过多种PDC钻头,但机械钻速提高不甚明显,为此,研究分析了PDC切削齿磨损对机械钻速的影响,提出了以加强PDC钻头的耐磨性为目标来提高机械钻速的设计观点,对PDC钻头的冠部形状、切削齿尺寸、切削齿排布、切削齿工作角等进行优化设计,设计的钻头在吐哈核3井进行了钻井试验。结果表明：设计的新钻头机械钻速与使用过的两种PDC钻头相比分别提高了29%和92.5%,且钻头钻时60 min以上时,有轻微磨损,仍可继续使用。     

超声振动钻削减摩机制研究与试验分析

在振动钻削加工原理的基础上建立振动钻削过程中平均摩擦力的数学模型,分析动载荷对平均摩擦力的影响规律。在超声振动钻削试验装置上对0Cr17Ni4Cu4Nb不锈钢进行了普通钻削和超声振动钻削试验,对比分析了孔壁表面粗糙度、钻头磨损形貌和切屑形状。结果表明:超声振动钻削能够减少平均摩擦力;通过观察加工后钻头与孔的表面形貌,超声振动钻削钻头磨损程度低,孔壁表面粗糙度值小,具有更好的断屑、排屑性能。     

Wear characteristics of the cemented carbide blades in drilling limestone with water jet

Drilling hard rock with water jet is considered to be an efficient way to improve the work life of the cemented carbide blade. In this paper, cemented carbide material YG-6 is used on the drill bit in limestone drilling with water jet. Wear characteristics of the cemented carbide blades in drilling limestone with water jet is studied. Experiment results showed that the water jet pressure and nozzle diameter played an important influence on the wear rates of the cemented carbide blades in the drill bits. The wear rates of YG-6 blades decreased when the jet pressure increased. But the decline speed of wear rates was not even, it declined more and more slowly when the jet pressure upon 10 MPa. It was also showed that wear rates decrease with the increase of the nozzle diameter in the drill bit, for the bigger nozzle diameter could provide more impact force which could reduce the mechanical force on the YG-6 blades. SEM photographs were taken to characterize the wear mechanism of the cemented carbide blades in limestone drilling with water jet. Surface analysis demonstrated that cemented carbide blades in limestone drilling with water jet showed circular action of brittle fracture, grain pullout and polishing, which induced material removal process.     

多元纳米颗粒强化WC–青铜基金刚石钻头胎体材料

为提高孕镶金刚石钻头胎体性能,使其更好地满足钻探需求,向WC–青铜基胎体材料中加入纳米NbC和纳米WC颗粒,研究其对胎体力学性能、微观结构的影响。利用配方均匀设计法、回归分析和规划求解得到纳米颗粒的最优添加量,并烧制钻头开展室内钻进试验。结果表明：加入纳米NbC和纳米WC后,WC–青铜基胎体材料的硬度和抗弯强度最高提高25.23%和5.73%;含金刚石的胎体材料的耐磨性明显增强,其磨耗比最高升高57.4%;金刚石与胎体之间结合得更加紧密。纳米颗粒强化后的孕镶金刚石钻头的机械钻速提高19.63%,单位进尺工作层消耗减少32.84%,说明纳米颗粒能强化孕镶金刚石钻头,提高其钻进效率,并延长钻头寿命。     

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.     

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。     

Drilling of carbon composites using a one shot drill bit. Part II: empirical modeling of maximum thrust force

In order to extend tool life and improve quality of hole drilling in carbon composite materials, a better understanding of ‘one shot’ hole drilling is required. This paper describes the development of an empirical model of the maximum thrust force and torque produced during drilling of carbon fiber with a ‘one shot’ drill bit. Shaw's simplified equations are adapted in order to accommodate for tool wear and used to predict maximum thrust force and torque in the drilling of carbon composite with a ‘one shot’ drill bit. The mathematical model is dependent on the number of holes drilled previously, the geometry of the drill bit, the feed used and the thickness of the workpiece. The model presented here is verified by extensive experimental data.     

水平井PDC钻头优化设计与应用

同常规直井、定向井聚晶金刚石（polycrystalline diamond compact,PDC）钻头相比,水平井钻头保径更易磨损、导向能力要求更高、切削齿所受冲击载荷更大。针对鄂尔多斯盆地红河油田水平段地层特点,通过室内试验优选切削齿尺寸和后倾角;针对水平井钻头的特点,设计了浅内锥、短外锥、大冠顶圆弧的钻头剖面形状,"主动保径齿+低摩擦保径块"的加强型保径及非对称、多喷嘴布置的加强水力结构。现场应用表明:新型钻头相比区块普通钻头,进尺提高了193%,机械钻速提高了132%。      

钎焊地质金刚石钻头的试验与研究

为探索钎焊技术在地质金刚石钻头制造中的应用,本文在分析与比较钎焊法、电镀法和热压法各自优缺点的基础上,介绍了钎焊金刚石钻头的制作工艺,并采用N i-Cr合金钎料制作了35 mm、50mm、70 mm三种规格的薄壁钻头;对试制的钻头进行了室内钻进试验,钻进材料为混凝土、钢筋混凝土和花岗岩。试验发现,烧结温度和钎焊材料中添加剂的成分与含量对金刚石钻头的性能有着非常重要的影响,烧结温度为980℃时钻头的性能最好,加入低熔点的Cu合金可以明显改善钎料与基体的浸润性。钻进结果表明:钎焊地质金刚石钻头具有金刚石出刃高,钻进时效好,寿命长等优点,该技术在金刚石钻头领域的开发与运用中具有重要的意义。     

Drilling of carbon composites using a one shot drill bit. Part I: Five stage representation of drilling and factors affecting maximum force and torque

The thrust force and torque produced during drilling contain important information related to the quality of the hole and the wear of the drill bit [1]. In this paper, the force and torque produced during drilling of carbon fibre using a ‘one shot’ drill bit is investigated. The signals in the time domain were divided into stages and common problems and defects associated with each stage discussed. It is also shown how tool wear and thickness of the workpiece affect the thrust force and torque throughout the drilling process. The findings of this paper are used to develop a mathematical model of the maximum thrust force and torque as described on Part II of this paper and are a valuable reference for future optimisation of drilling carbon composites with a ‘oneshot’ drill bit.     

3D打印金刚石复合片及其钻头的研究进展

PDC钻头已成为油气勘探领域的首选钻头类型，日益提升的PDC钻头性能要求特别是钻进效率要求给钻头制造带来较大挑战。钻头工作面结构改进是PDC钻头实现高效破岩的关键，但这给PDC钻头制造带来难题。3D打印技术是一种新型的快速成形技术，具有制造任意复杂形状结构、个性化定制和创意设计的优点，将3D打印工艺应用于PDC及其钻头的生产是未来发展的必然趋势。本文中介绍了目前用于制备PDC及其钻头的3D打印技术的基本原理，包括光固化成形技术（SLA）、熔融沉积技术（FDM）、激光选区烧结（SLS）、激光选区熔化技术（SLM）和喷墨粘粉式（3DP）等；总结了现有3D打印技术在PDC及其钻头制造方面的研究进展，并对未来3D打印PDC钻头的发展进行了展望。     

骨钻孔钻削力与钻削温度的研究综述

骨钻孔手术是关键的外科手术之一,广泛应用于修整骨折及颅骨开孔等方面.在骨钻孔手术过程中,医疗钻头与骨组织相互作用,不可避免地产生钻削力和钻削温度,从而导致不同程度的骨损伤.基于当前研究现状,综述了实验法和仿真分析法2种骨钻孔研究方法;阐述了医疗钻头钻削温度的产生、测量及其影响因素;分析了钻头参数、钻头设计及超声辅助钻削...