CVD金刚石条强化孕镶金刚石钻头的试验研究

本文将经过激光切割的CVD金刚石条镶嵌到传统的孕镶金刚石钻头胎体中,研制了一种新型的硬支点强化型金刚石钻头,以提高钻头在坚硬地层中的钻进效率和使用寿命。介绍了该新型钻头的设计及制造工艺,并进行了室内钻进试验。结果表明：与聚晶金刚石柱强化孕镶金刚石钻头相比,CVD金刚石条强化的孕镶金刚石钻头的钻进效率较高,达5．575m／h,且该钻头的磨损程度更小,使用寿命长。在钻进过程中更加稳定.     

孕镶金刚石钻头性能变化规律及机理

孕镶金刚石钻头有一个共同的性能变化规律,在等压钻进时,随着进尺,钻头时效不断降低,直到最后出现钻头打滑现象,尤其是在孔底压力低的时候。作者对这种现象做了研究,发现产生这种现象的原因,是由于唇面上金刚石新陈代谢规律所决定的,并给出唇面上金刚石新陈代谢的变化全过程。     

高效率孕镶金刚石钻头的研制

分析了研制高效率孕镶金刚石钻头的意义,讨论了高效率对孕金刚石钻头的配方要求,设计了高效率孕镶金刚石钻头的配方参数,现场试验表明,研制的高效率孕镶金刚石钻头的使用效果比较理想。     

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 ...     

金刚石孕镶钻头的面形状

本文对金刚石孕镶钻头磨损机理进行了分析。讨论了目前钻探领域广泛使用的几种典型的金刚石孕镶钻头唇面形状的优缺点。最后从理论的角度改进了金刚石钻头的唇面形状。并阐述了制造该形状钻头的方法及该钻头的优越性。     

孕镶金刚石钻头钻进花岗岩岩屑特性室内试验研究

岩屑的特征参数是影响其环空上返的一个重要因素。为研究孕镶金刚石钻头钻进花岗岩所产生的岩屑特性,开展室内微钻试验。研究发现碎岩产生的岩屑在一定范围内呈单峰值分布,且岩屑粒度分布范围与钻压、转速等钻进参数有关;在一定程度上岩屑峰值粒径随着钻压的增大而变大,随着转速的增大而变小。进一步显微观察岩屑形貌特征,发现岩屑颗粒基本小于岩石原矿物颗粒尺寸,且岩屑颗粒多呈单一矿物成分,较少有多种矿物相互混杂的岩屑颗粒;显微观察岩屑与岩石表面形貌特征,发现孕镶金刚石钻头钻进花岗岩时以体积破碎的方式为主、塑形微切削方式为辅。     

自形成同心圆齿孕镶金刚石钻头研究

通过钻头胎体配方的分区设计，钻头在钻进过程中，其唇面会自动形成同心圆齿，该类钻头具有钻进时效高，使用寿命相对延长，破碎岩石时的稳定性好，钻进质量明显改善等优点，并详细阐述同心圆齿金刚石钻头的碎岩机理，研究表明，设计的自形成同心圆齿钻头，使钻头在碎岩机理方面有所突破，与普通钻头相比，自形成同心径向环齿钻头在时效和寿命方面均有所提高。     

低温电镀热压金刚石孕镶块钻头的研制

采用低温电镀工艺（室温）生产热压金刚石孕镶块钻头，或者说金刚石孕镶块镶嵌在钻头刚体上，然后在其表面镀覆生层金刚石复合镀层使其与刚体相结合从而使其避免银焊对金刚石二次热损伤，同时这处钻头具有胎体性能可调性好和内外保径强的优点。深受生产用户好评。     

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。     

制作电镀孕镶金刚石钻头的几个关键问题

通过对生产实践经验的积累总结，分析了影响电镀孕镶金刚石钻头使用效果的因素，对生产环节中金刚石对使用性能的影响以及胎体性能和电镀工艺对使用性能的影响进行了探讨。     

基于模糊聚类算法的孕镶金刚石钻头出刃图像分割

本文针对孕镶金刚石钻头唇面彩色图像的特征,采用模糊聚类方法对图像中的色彩进行了聚类分析,以提取出刃的金刚石图像。在图像预处理的基础上,对比了两种图像色彩描述空间对聚类分析的影响,并把模糊聚类分析结果与最大类间方差阈值分割法的分析结果进行了比较。结果表明：模糊聚类方法可对孕镶金刚石唇面的颜色进行有效分类,并准确提取出刃的金刚石图像;用RGB的线性变换量描述金刚石唇面图像,比用Lab色彩空间描述图像,更能得到理想的分割效果;对于孕镶金刚石唇面图像而言,最大类间方差阈值分割法难以区分金刚石颗粒和犁沟,分割效果不如模糊聚类法。     

WC strengthened W–Cu nanocomposite powder synthesized by in-situ reactions

A novel strategy to prepare W–Cu nanocomposite powder with WC nanoparticles for strengthening was proposed. The feasibility and mechanisms of the present in-situ reactions method for synthesizing multicomponent powders were demonstrated by both thermodynamic calculations and experiments. The W-Cu-WC nanopowder can be prepared at a low temperature with pure phase constitution and homogeneous microstructure with a mean particle size of 60 nm. Owing to in-situ reactions, the orientation relationship of WC and W is formed, which facilitates strong bonding between the strengthening particles and matrix. The new method is applicable to synthesize a variety of composite powders with tailorable phase and particle size.     

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.     

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%).     

新型优质孕镶金刚石钻头研制

针对钻进中硬-坚硬岩层时钻头钻进效率低、寿命短等情况,研制了一种新型优质孕镶金刚石钻头.该钻头结合运用了交错式唇面和自形成同心圆齿设计,以及金刚石在胎体中的有序排列技术,提高了钻头在钻进该类岩层时的钻进效率及寿命.本文从理论上分析了这种新型钻头的碎岩机理,自形成同心圆齿钻头,使钻头在碎岩机理方面有所突破,并详细阐述了这种钻头的优越性:自形成同心圆齿交错式唇面钻头,减少了工作中钻头唇面与岩石的接触面积,提高了钻头对岩石的摩擦系数和摩擦力,有利于岩石体积破碎,提高碎岩速率;工作层胎体中金刚石按均匀有序方式排列,提高了金刚石的利用率,使钻头的钻进效率和使用寿命得到提高,同时提高了钻进质量的稳定性.实际应用中95/64 mm新型钻头的钻进时效比同规格普通钻头提高了52%,寿命提高了33%,钻进效果良好.     

Preparation of WC nanoparticles by twice ball milling

In order to improve the ball milling efficiency of WC powders and thus to fabricate nano-grained WC–Co cemented carbides with high mechanical properties, WC nanoparticles were prepared by twice ball milling in nylon vessels. The best technology to disperse WC powders in alcohol was investigated at first. Based on the dispersion results, 2 wt.% PEG was used with La₂O₃ as additive to improve ball milling efficiency. The particle size, crystal structure, surface morphology and surface properties were tested by a laser particle sizer, XRD, FE-SEM and FT-IR, respectively. During the first ball milling, sample d achieved the best milling performance, including average particle size (168 nm) and grain size (27.2 nm) among samples a (pure WC), b (with PEG), c (with La₂O₃) and d (with PEG and La₂O₃). La₂O₃ could greatly decrease particle size and grain size while PEG could narrow particle size distribution. During the second milling, the particle size and grain size of sample d reached 89 nm and 13.2 nm at 96 h, respectively. The results indicated that twice ball milling can greatly improve particle size and grain size compared with the first ball milling, and further narrow the size distribution. In conclusion, multiple ball milling can reduce the particle size of certain powders with suitable milling technology.     

Low-alloy high-speed steels for drill bits produced from cast blanks

Conclusion The steels investigated have satisfactory cutting and technological properties and can be recommended for manufacturing drill bits from cast blanks for more complete utilization of high-speed steel scrap.Tomsk Polytechnical Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 8, pp. 28–31, August, 1972.     

Effects of special drill bits on drilling-induced delamination of composite materials

Drilling is the most frequently employed operation of secondary machining for fiber-reinforced materials owing to the need for joining structures. Delamination is among the serious concerns during drilling. Practical experience proves the advantage of using such special drills as saw drill, candle stick drill, core drill and step drill. The experimental investigation described in this paper examines the theoretical predictions of critical thrust force at the onset of delamination, and compares the effects of these different drill bits. The results confirm the analytical findings and are consistent with the industrial experience. Ultrasonic scanning is used to evaluate the extent of drilling-induced delamination. The advantage of these special drills is illustrated mathematically as well as experimentally, that their thrust force is distributed toward the drill periphery instead of being concentrated at the center. The allowable feed rate without causing delamination is also increased. The analysis can be extended to examine the effects of other future innovative drill bits.     

钎焊镀钛金刚石钻头的研制及其钻进性能分析

分别使用Ni-Cr和Cu-Sn-Ti等2种合金钎料真空钎焊制作镀钛和无镀层金刚石钻头,通过钻进玻化砖试验,研究了4类钻头的钻进性能。试验结果表明:Ni-Cr钎料钎焊制作的镀钛金刚石钻头与无镀层金刚石钻头比较,钻头平均寿命下降了41.7%;Cu-Sn-Ti钎料钎焊制作的镀钛与无镀层金刚石钻头比较,钻头平均寿命相当,但镀钛金刚石钻头的钻孔效率更高,并对其机理进行了分析。      

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.