Penetration and impact resistance of PDC cutters inclined at different attack angles

1　ＩＮＴＲＯＤＵＣＴＩＯＮＳｉｎｃｅｔｈｅｉｎｔｒｏｄｕｃｔｉｏｎｏｆｐｏｌｙｃｒｙｓｔａｌｌｉｎｅｄｉａｍｏｎｄｃｏｍｐａｃｔ (ＰＤＣ)ｂｉｔｓｉｎｔｈｅｍｉｄ 1970’ｓ ,ｔｈｅｓｅｔｏｏｌｓｈａｖｅｇａｉｎｅｄｉｎｃｒｅａｓｉｎｇｌｙｗｉｄｅａｃｃｅｐｔａｎｃｅ .Ｔｈｉｓｉｓｎｏｔｂｅｃａｕｓｅｏｆｔｈｅｔｏｏｌｉｔｓｅｌｆ ,ｂｕｔａｌｓｏｂｅｃａｕｓｅｏｆｔｈｅａｄ ｖａｎｃｅｓｔｈａｔｍａｄｅｉｎｔｈｅｍａｔｅｒｉａｌｓｕｓｅｄｔｏｆｏｒｍｔｈｅｂｉｔｓａｎｄｉｎｔｈｅｂｉｔｄｅｓｉｇｎｓ…     

基于火山岩地层钻井岩心资料的PDC钻头设计改进

PDC钻头在钻进火山岩地层过程中,技术性能常得不到充分发挥,针对火山岩地层岩心资料,从复合片、切削齿受力、齿型、切削齿的角度等方面设计和改进了PDC钻头。研究分析了剖面形状、布齿、切削齿工作角等设计对PDC钻头性能的影响。提出了以加强钻头的稳定性、耐磨性和提高钻速为目标的设计观点。研制的新型钻头采用抛物线形剖面,中密度布齿,切削齿后倾角在10°-15°范围内变化。结果表明：与牙轮钻头相比,PDC钻头钻速提高了约20％,每米钻井成本降低了27％。     

Cutting capacity of PDC cutters in very hard rock

An experimental programm of investigating the cutting capacity of PDC flat cutters in very hard rock has been performed, Experiments include both the cutting of PDC fixed at different angles on the granite core or bar and linear cutting with different static thrust on the block of granite, The effects of the rough degree of rock surface, cutting angles,and static thrust on the cutting capacity of PDC in very l‘mrd rock were investigated and analyzed. The results show that the single modp of rotarv drilling llsing PDC cutterg is not annlied fnr very hard rocks.     

Effect of cobalt content on the performance of polycrystalline diamond compacts

Cobalt was an indispensable role in the damage of a PDC cutter due to its inevitable adverse thermal effect like thermal catalysis, thermal expansion and thermal oxidation in the welding and drilling process, while the quantitative studies on its serial thermal damage effect were still seldom reported. In order to understand the damage mechanism of a PDC cutter and therefore design better products, it was quite necessary to study the roles of cobalt in the PDC cutter by a quantitative means. In present study, the total cobalt content of the PCD layer of polycrystalline diamond compacts were adjusted by blending different amount of microsized cobalt powder in the mixed diamond grains and the infiltrated cobalt from the cemented carbide cylinder during the HTHP sintering process. The sintered PDC cutters were examined by XRD, SEM, EDX, vertical lathe tests, and impact tests, and it was found that the abrasive ratios of the fabricated PDC cutters were strongly dependent on the cobalt content of sintered diamond layers. The PDC cutter without adding cobalt powder exhibited the best resistance to the abrasion, while the PDC cutters sintered by adding 4% mass of cobalt powder demonstrated the worst abrasive ratio, which was the direct proof confirming that by decreasing the content of residual cobalt in the PCD layer the resistance of the PDC cutter to the abrasion would be improved significantly. A non-destructive characterization method was adopted based on the statistical calculation was proposed by using Matlab and Image-J software to quantitatively explore the relationship between the cobalt content as well as the average size of residual cobalt in the PCD layer and the abrasion performance, which opened a new technical route for the disclosure of cobalt-dependent abrasion resistance for the PDC cutter analysis. Moreover, a cobalt-rich narrow zone was found to appear in the interface of PCD/cemented carbide, which was deduced to be the main reason to cause the delamination of PCD layer from the cemented carbide. It was also interesting to find that the percentage of added cobalt powders seemed no adverse effect on the impact performance of the PDC cutters. The conclusion of present study about the cobalt role in the PDC performance was quite good for understanding the PDC damage modes and helped for the better design and fabrication of PDC.     

不同斧型钻齿切削刃角下的破岩方式

为进一步理解斧型 PDC钻齿破岩机理,建立PDC钻齿破岩的3D有限元模型,对3种不同切削刃夹角的斧型PDC钻齿破岩方式开展对比研究。结果表明:与150°和165°的钻齿相比,135°的斧型钻齿受到的剪切力和切削力更小,从而具有更高的破岩效率。在相同的后倾角、相同的切削深度和相同的切削力下,165°斧型钻齿切削力波动较小,稳定性更高。与立式车床上的实验数据相比,仿真结果与实验结果总体趋势一致,误差在可接受范围内。      

石油天然气钻采用PDC切削齿的最新发展

本文介绍了近年来PDC钻头的设计理念和PDC切削齿的最新技术动向,PDC切削齿的若干关键技术,以及国际上最新采用的测试技术。通过提高金刚石含量,加强D-D键结合,优化界面几何形状,减少内应力,精细控制各种原辅材料的质量,最终提高PDC切削齿的综合性能。文中介绍了PDC超声波逐行扫描探伤技术,最新的重负荷检测耐磨性能,以及耐热性和抗冲击性的检测技术。最后还对石油钻井市场现状进行了介绍。     

Cutting force and dimensional surface error generation in peripheral milling with variable pitch helical end mills

Mechanics of cutting force and dimensional surface error generation are presented for variable pitch helical end mills. It has been known that the variable pitch cutters reduce the chatter vibrations by disturbing the regeneration mechanism in dynamic milling. In this paper, it is also demonstrated that the variable pitch cutters reduce the dimensional surface errors caused by the static deflection of slender end mills. Since the pitch angles between the adjacent flutes are different, each flute experiences different chip loads, hence leading; to the varying surface errors imprinted at each tooth period. The excess surface errors left by the flutes, which have larger chip loads, are removed by the following flutes with smaller effective chip loads due to variable pitch. Unlike in the case of uniform pitch cutters, the regeneration of chip thickness mechanism is always present in milling with a statically flexible, variable pitch end mills. A mathematical model. of force and surface prediction, which considers the chip regeneration mechanism under static end mill deflections, is presented with experimental verifications. Up to 20% reduction in surface errors are achieved by using variable pitch over uniform pitch cutters.     

Polycrystalline diamond cutters sintered with magnesium carbonate in cubic anvil press

Polycrystalline diamond cutters (PDC) were sintered with magnesium carbonate (MgCO₃) around 8 GPa and 2200–2400 °C in a single-stage cubic anvil press. Different analyzing techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) were applied to characterize the micro-structure, sintering behavior, and composition of the diamond-MgCO₃ system. Wear resistance, thermal stability, and rupture strength of MgCO₃-sintered PDC were compared against conventional cobalt-sintered PDC. An improvement in performance was observed from our laboratory tests, which may enable MgCO₃-sintered PDC to be a functional superhard material for the cutting, drilling, and machining industries.     

我国复合超硬材料行业发展概况

介绍了我国超硬材料行业中的复合超硬材料领域20年的发展概况,详述了复合超硬材料领域3大类产品:钻探/工程用聚晶金刚石复合片、PCD/PCBN刀具用复合片、聚晶金刚石拉丝模坯,在高速发展期、转型升级期的发展历程,探讨了我国在该领域未来的发展趋势。      

适合强研磨性硬地层的新型混合钻头设计及现场应用

为提高金刚石复合片(polycrystalline diamond compact,PDC)钻头在强研磨性硬地层中的破岩效率和使用寿命,设计2只由PDC切削齿和金刚石孕镶块组合作为切削单元的PDC-金刚石孕镶块新型混合钻头,并在冀中某断层区块石英岩地层进行现场试验。试验结果表明:与同井段使用过的牙轮钻头的平均值相比,1#PDC-金刚石孕镶块混合钻头的平均机械钻速提高52.30%,平均钻头进尺提高97.30%;与牙轮钻头的平均值和M1375D PDC钻头相比,2#PDC-金刚石孕镶块混合钻头的平均机械钻速分别提高30.85%和 32.30%,平均钻头进尺分别提高70.50%和 47.40%。PDC-金刚石孕镶块混合钻头极大地提高了强研磨性硬地层中的钻进效率,降低了钻井成本。      

硬岩地层PDC钻头不良工况原因分析与改善措施

传统PDC钻头在硬岩地层钻进时,不良工况多,钻头寿命及钻进效率非常低。为了找出硬岩地层PDC钻头不良工况发生的原因,以四川元坝地区须家河组致密砂岩为例,建立单个PDC复合片切削岩层的模型,分别对模型中复合片及微小岩块进行受力分析,发现单个复合片受力随切入岩石弧长、岩石的内摩擦角及黏聚力的增加而增加。视所有复合片破岩的临界钻压及扭矩为整个钻头受到岩石的作用力,钻头受力超出转盘的输出钻压及扭矩会导致不良工况的发生。最后,从提高PDC钻头结构使其能适应硬岩钻进,及使用PDC钻头伴侣来改善PDC钻头的切削条件两方面提出了PDC钻头不良工况的改善措施。     

Control of exaggerated tungsten carbide grain growth at the diamond-substrate interface of polycrystalline diamond cutters (PDC)

Exaggerated tungsten carbide grain growth is common at the interface between the diamond table and the cobalt-cemented tungsten carbide (WC-Co) substrate in polycrystalline diamond cutters (PDC). The exaggerated WC grains at the interface can grow as large as 50 μm with an aspect ratio of 50:1. These large grains can also grow as clusters. The presence of large WC grains/clusters creates weakness at the diamond-substrate interface and impairs the strength of the PDC tool. In the present investigation, we tried to understand the root cause of exaggerated WC grain growth at the interface. Our findings show that WC grain growth at the interface decreases with a decrease in the carbon/tungsten (C/W) ratio. By adding 5 wt.% pure tungsten powder to the diamond, the C/W ratio decreased and we found no WC grain growth. By adding fully stoichiometric WC, which has 6.13 wt.% carbon, grain growth was reduced but still observed. Sintering on a substrate having η-phase (carbon deficient phase) also decreased the C/W ratio, and we did not observe WC grain growth.     

铣削大理石切削参数对PCD刀具磨损的影响

目的探索PCD刀具磨损机理,以延长刀具使用寿命。方法设计正交试验,研究不同加工参数切削大理石对刀具磨损的影响情况。分析主轴转速、进给速度与切削深度对PCD刀具磨损量的影响规律,以优化切削参数来减小刀具磨损量。根据经验公式,建立单位时间刀具磨损量和固定行程磨损量模型。通过对试验过程刀具振动情况记录,结合刀具实际磨损情况,给出了刀具磨损等级。结果主轴转速的提高可以减少刀具磨损量,进给速度的增大会加剧刀具磨损,而切削深度小于1 mm时,其对刀具磨损量的影响很小,但切削深度大于1 mm时,继续增大切削深度会使刀具快速磨损。利用预测模型能够很好地对刀具磨损情况进行预判,根据磨损等级,得出刀具与机床发生共振时磨损最为严重,在刀具表面产生了明显的犁沟、磨损以及金刚石颗粒脱落。结论在实际加工中,通过提高主轴转速、降低进给速度以及减小切削深度有助于增强刀具的耐用度,避开共振切削参数可以有效降低刀具磨损,主轴转速、进给速度、切削深度分别为12000r/min、500 mm/min、0.5 mm时的切削效果较佳,有最小的刀具磨损量。     

预防鸽尾铣刀淬火裂纹的工艺探索

分析了导致鸽尾铣刀产生淬火裂纹的因素，设计了能有效预防鸽尾铣刀淬裂的热处理工艺。实践证明，经过改进的热处理工艺能有效地防止鸽尾铣刀产生淬火裂纹，可推广应用于那些大直径、截面变化大和形状复杂的刀具。     

纳米TiN改性金属陶瓷刀具的磨损性能

Ti(C,N)基金属陶瓷由于具有优良的综合性能因而被广泛用作刀具材料。本文探讨了纳米 Ti N对 Ti C基金属陶瓷刀具显微组织的影响 ;还研究了它与 Ti(C,N)基金属陶瓷刀具 (cermetμm,下同 )及 YG8刀具在切削灰铸铁时的磨损曲线及磨损机理。结果表明 ,纳米 Ti N改性 Ti C基金属陶瓷刀具 (cerm etnm,下同 )的效果显著 ;与 cermetμm刀具及 YG8刀具相比 ,cermetnm刀具具有更高的寿命与耐磨性 ;崩刃是 cermetnm刀具主要的失效形式     

金刚石-硬质合金复合片的耐磨性测试方法研究

金刚石-硬质合金复合片的耐磨性是一个非常重要的技术指标,但迄今为止国际上尚无统一的PDC耐磨性测试标准。本文在分析我国和乌克兰评价PDC耐磨性方法优缺点的基础上进行了对比性研究,指出乌克兰超硬材料研究所按复合片在实验台上切削岩块的磨损高度和面积来评价的方法,更接近于孔底岩石破碎过程,PDC的几何磨耗量可更全面真实地反映复合片在钻探生产中的工作寿命。同时,讨论了乌克兰方法需要完善的地方。     

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。     

基于热性能分析的PDC切削齿选型试验研究

为提高PDC切削齿选型的可靠性,从热性能角度出发,分别对不同厂家的PDC切削齿进行常温激光拉曼、高温激光拉曼及热重等分析,并结合其高温磨耗比测试,分析PDC切削齿的残余应力、石墨化转变、热稳定性以及高温耐磨性等,综合评价不同厂家的PDC切削齿性能;同时,制作φ94 mm四翼弧角PDC钻头并进行现场钻进试验。结果表明:现场试验结果与PDC切削齿热性能检测和分析得出的结论基本一致。热性能优异的PDC切削齿高温磨耗比高,钻进性能表现出色,平均时效为25.0 m/h,平均寿命为266 m,相对于其他热性能稍差的PDC切削齿的均有不同程度的提高。故从微观角度完善和补充了PDC宏观检测方法,有利于提高PDC切削齿选型的准确性。      

PDC钻头自动焊接技术

在对PDC钻头的焊接性进行分析的基础上，选择了火焰加热的钎焊方法，研制出了适用于PDC钻头火焰钎焊，并具有专利技术的复合片焊接温度测控系统和数控变位操作系统，实现了复合片与钻头基体焊接工艺参数的自动控制和复合片焊接位置的数控定位，在稳定PDC钻头的焊接质量、提高焊接效率、降低劳动强度方面迈出了重要的一步。     

聚晶金刚石复合片(PDC)应力表征方法的探讨

聚晶金刚石复合片是采用HPHT方法生产的，所以不可避免地在界面处、以及聚晶金刚石层内部的缺陷处存在大量的残余应力。本文主要围绕聚晶金刚石复合片的应力表征问题进行了实验和理论分析。实验、研究表明，聚晶金刚石复合片在聚晶金刚石层内存在着宏观应力和微观应力，即第一类内应力、第二类内应力；聚晶金刚石表面应力的大小可以反映聚晶金刚石层的应力存在状况；XRD方法可以用于聚晶金刚石复合片应力的表征。