Hole cleaning evaluation and installation spacing optimization of cuttings bed remover in extended-reach drilling

In extended-reach or long-horizontal drilling,cuttings usually deposit at the bottom of the annulus.Once cuttings accumulate to a certain thickness,complex problems such as excessive torque and drag,tubing buckling,and pipe stuck probably occur,which results in a lot of non-productive time and remedial operations.Cuttings bed remover can efficiently destroy deposited cuttings in time through hydraulic and mechanical stirring effects.This paper aims to build a method for hole cleaning evaluation and installation spacing optimization of cuttings bed remover to improve the wellbore cleaning effect.Firstly,a Computational Fluid Dynamics approach with Eulerian—Eulerian multiphase model was utilized to investigate the mechanism of cuttings transportation,and a new type of cuttings bed remover was designed.Next,an evaluation method of hole cleaning effect of remover was established.After that,the effects of several drilling parameters on hole cleaning including flow rate of drilling fluid,rotational speed of drillpipe,rate of penetration,wellbore size,rheological property of drilling fluid,and remover eccentricity on the performance of cuttings bed remover were investigated.The results demonstrate that the new type of remover with streamline blade performs better than conventional removers.The efficiency of hole cleaning is greatly improved by increasing the rotational speed of drillpipe,flow rate of drilling fluid,remover eccentricity,and 6 rpm Fann dial reading for drilling fluid.While higher rate of penetration and large wellbore size result in worse hole cleaning.These findings can serve as an important guide for the structure optimization design of cuttings bed remover and installation spacing of removers.

Design and Numerical Simulation of Dust Removal System for Sutomotive Iongitudinal Beam Plasma Cutting

To improve the poor efficiency of the dust removal system in the plasma cutting station of automotive longitudinal beams,and reduce the cutting surface quality degradation due to dust,a bottom-side suction dust removal system is designed,and the dust removal effect is optimized through the setting of the following dampers and diversion plates.The result of numerical simulation indicates that the particle collection rate can reach 99.44%,and the field test also proves the effectiveness of the dust removal system,which is of guiding significance for the transformation of other similar dust removal systems.

An autotrophic nitrogen removal process:Short-cut nitrification combined with ANAMMOX for treating diluted effluent from an UASB reactor fed by landfill leachate

A combined process consisting of a short-cut nitrification （SN） reactor and an anaerobic ammonium oxidation upflow anaerobic sludge bed （ANAMMOX） reactor was developed to treat the diluted effluent from an upflow anaerobic sludge bed （UASB） reactor treating high ammonium municipal landfill leachate.The SN process was performed in an aerated upflow sludge bed （AUSB） reactor （working volume 3.05 L）,treating about 50% of the diluted raw wastewater.The ammonium removal efficiency and the ratio of NO 2 N to NOx-N in the effluent were both higher than 80%,at a maximum nitrogen loading rate of 1.47 kg/（m 3 ·day）.The ANAMMOX process was performed in an UASB reactor （working volume 8.5 L）,using the mix of SN reactor effluent and diluted raw wastewater at a ratio of 1：1.The ammonium and nitrite removal efficiency reached over 93% and 95%,respectively,after 70-day continuous operation,at a maximum total nitrogen loading rate of 0.91 kg/（m 3 ·day）,suggesting a successful operation of the combined process.The average nitrogen loading rate of the combined system was 0.56 kg/（m 3 ·day）,with an average total inorganic nitrogen removal efficiency 87%.The nitrogen in the effluent was mostly nitrate.The results provided important evidence for the possibility of applying SN-ANAMMOX after UASB reactor to treat municipal landfill leachate.

Experimental Investigation of Material Removal in Elliptical Vibration Cutting of Cortical Bone

To benefit tissue removal and postoperative rehabilitation,increased efficiency and accuracy and reduced operating force are strongly required in the osteotomy.A novel elliptical vibration cutting(EVC)has been introduced for bone cutting compared with conventional cutting(CC)in this paper.With the assistance of high-speed microscope imaging and the dynamometer,the material removals of cortical bone and their cutting forces from two cutting regimes were recorded and analysed comprehensively,which clearly demonstrated the chip morphology improvement and the average cutting force reduction in the EVC process.It also revealed that the elliptical vibration of the cutting tool could promote fracture propagation along the shear direction.These new findings will be of important theoretical and practical values to apply the innovative EVC process to the surgical procedures of the osteotomy.

Optimization of material removal strategy in milling of thin-walled parts

The optimal material removal strategy can improve a geometric accuracy and surface quality of thin-walled parts such as turbine blades and blisks in high-speed ball end milling.The dominant conception in the material removal represents the persistence of the workpiece cutting stiffness in operation to advance the machining accuracy and machining efficiency.On the basis of theoretical models of cutting stiffness and deformation,finite element method (FEM) is applied to calculate the virtual displacements of the thin-walled part under given virtual loads at the nodes of the discrete surface.With the reference of deformation distribution of the thin-walled part,the milling material removal strategy is optimized to make the best of bracing ability of still uncut material.This material removal method is summarized as the lower stiffness region removed firstly and the higher stiffness region removed next.Analytical and experimental results show the availability,which has been verified by the blade machining test in this work,for thin-walled parts to reduce cutting deformation and meliorate machining quality.

单晶镍纳米切削材料去除行为与机理研究

单晶镍纳米尺度加工时的材料去除机理对实现其超精密加工尤为重要。为此,借助分子动力学仿真研究单晶镍纳米切削时的力热行为、表面/亚表面形成特征以及塑性变形机制以揭示材料去除机理。结果表明单晶镍纳米切削时,有序的镍原子在刀具挤压和剪切作用下以非晶结构的形式被去除,部分具有面心立方(face center cubic, FCC)结构的镍原子转变成密排六方(hexagonal close-packed, HCP)结构和非晶结构,主导了相变与非晶化;同时出现伯氏矢量分别为1/6<112>、1/3<100>、1/6<110>、1/3<111>以及1/2<110>的位错线。单晶镍纳米切削时的塑性变形机制为相变、非晶化和位错滑移。在切削过程中,由于几何条件与能量条件被同时满足,发生1/2<110>全位错转变为1/6<112>不全位错的位错反应。在切削力热的作用下,已加工亚表面出现了位错环、梯杆位错、棱住位错、V型位错、原子团簇和空位等缺陷结构。相比于(100)晶面和(110)晶面,沿(111)晶面切削有利于减小亚表面缺陷层深度。

钛合金深孔环形套料钻削切削液参数优化

为提高钛合金深孔环形套料钻削时的排屑性能,选取TC4钛合金棒材为研究对象,基于响应面法(box-behnken design, BBD)结合仿真试验开展了深孔环形套料钻削切削液参数优化研究。以切削液密度、切削液黏度、切削液流量为三参数输入条件,以第一刀齿断屑槽压力和断屑槽湍流动能为优化目标,建立影响因素与响应值之间的回归模型,探究三参数对响应值的影响规律。试验结果表明,切削液黏度与流量交互对两响应值的影响最大。切削液的最优参数为密度1 100 kg/m^(3)、黏度0.002 kg/(m·s)、流量180 L/min。物理试验验证表明,优化后的切削液可以明显的改善切屑形态,有利于提高排屑性能。

基于VERICUT的刀具切削参数优化

以分流叶轮为例,基于VERICUT软件提出了恒体积去除率和恒切削厚度的优化方式。试验证明该优化方法效果明显,极大提高了加工效率。

Friction behaviors in the metal cutting process:state of the art and future perspectives

Material removal in the cutting process is regarded as a friction system with multiple input and output variables.The complexity of the cutting friction system is caused by the extreme conditions existing on the tool–chip and tool–workpiece interfaces.The critical issue is significant to use knowledge of cutting friction behaviors to guide researchers and industrial manufacturing engineers in designing rational cutting processes to reduce tool wear and improve surface quality.This review focuses on the state of the art of research on friction behaviors in cutting procedures as well as future perspectives.First,the cutting friction phenomena under extreme conditions,such as high temperature,large strain/strain rates,sticking–sliding contact states,and diverse cutting conditions are analyzed.Second,the theoretical models of cutting friction behaviors and the application of simulation technology are discussed.Third,the factors that affect friction behaviors are analyzed,including material matching,cutting parameters,lubrication/cooling conditions,micro/nano surface textures,and tool coatings.Then,the consequences of the cutting friction phenomena,including tool wear patterns,tool life,chip formation,and the machined surface are analyzed.Finally,the research limitations and future work for cutting friction behaviors are discussed.This review contributes to the understanding of cutting friction behaviors and the development of high-quality cutting technology.

Analysis of Striation Formation and Suppression Strategy on Upper Edge of Cutting Surface in Laser Cutting

Metal laser cutting belongs to mature laser material processing technologies in industry applications. However, without understanding of the mechanism underlying the overall process, the improvement of the cutting quality is restricted. In this paper, an instantaneous melt removal model is presented to describe the process of material removal and striation formation. In the temperature field calculation, melted metal layer is removed when it grows to an assumed thickness. The effects of cutting parameters including cutting speed, gas pressure and laser power on the shape of striation are discussed. A novel method of getting striation free cutting surface is presented. Finally, laser cutting experiments of mild steel is conducted to validate the model. The striation variation trend can be well predicted by the model presented here and the disagreement may be caused by the coupling effect of cutting speed and critical thickness value.

弹性磨抛轮加工硅片面形预测模型及试验验证

目的为分析弹性磨抛轮磨削硅片面形精度变化的影响因素,优化加工参数以获得良好的磨削面形。方法通过建立考虑弹性磨抛轮转速、硅片转速、偏心距等参数的弹性磨抛轮磨粒运动轨迹模型,结合单颗磨粒切削深度,提出了弹性磨抛轮加工硅片的材料去除非均匀性预测方法,建立了基于弹性磨抛轮磨削硅片的面形预测模型,并通过不同转速比下的磨削试验验证了预测模型的准确性。结果面形预测模型仿真出的面形与弹性磨抛轮加工试验后的硅片面形一致,均呈“凸”形,且PV值随转速比的增大而增大。转速比为1时,磨削后硅片面形PV值为0.54μm,仿真模型计算出的PV值为0.49μm,转速比为5时,磨削后硅片面形PV值为2.12μm,仿真模型计算出的PV值为2.38μm。结论磨削试验面形PV值与模型计算面形PV值的预测误差小于13%,建立的面形预测模型能够成功预测硅片的面形规律,可以分析加工参数对硅片面形的影响规律。由面形预测模型分析可知,转速比对硅片面形精度有影响,且随着转速比的增加,硅片面形不断恶化,因此在实际加工中,应选择较小的转速比进行加工,以获得更优的硅片面形精度。

小井眼水平井洗井岩屑清除效率研究

为研究小井眼水平井洗井钻柱旋转时的岩屑清除规律,针对玛湖深层三叠系长水平井小井眼洗井工况,进行了相似试验设计,开展了岩屑启动流速和岩屑清除效率的试验研究。试验发现,采用不同排量冲洗岩屑床时,岩屑床呈现稳定运移、沙丘式波浪运移和整体运移等3种运移形态。试验研究了岩屑床稳定运移形态下岩屑粒径、排量和钻柱转速对岩屑启动流速及钻柱转速对岩屑床高度和形成稳定岩屑床所需时间的影响规律,分析了岩屑床整体运移形态下岩屑粒径、排量和岩屑床初始质量对岩屑床清除效率的影响。研究结果表明,岩屑粒径越小所需启动流速越低,钻柱旋转后等效岩屑启动流速降低45.5%,钻柱转速升高会使形成稳定岩屑床所需时间缩短,岩屑清除效率提高;当岩屑床发生整体运移后,较低排量下岩屑床清除速度受岩屑粒径影响较小,高排量下大粒径岩屑床的运移速度快。排量和钻柱转速是提高洗井过程岩屑床清除效率的关键,而现在洗井时钻柱转速较低,可适当提高钻柱转速,以提高洗井效率。

掺杂种类对磷化铟晶片切割损伤层及翘曲度的影响

研究了掺杂对磷化铟(InP)单晶切割损伤层及翘曲度的影响。使用化学腐蚀法研究了相同切割工艺条件下不同掺杂晶片的损伤层厚度的差别,得到了切割损伤层厚度以及在相同腐蚀条件下不同掺杂晶片的本征腐蚀速率。4种InP晶片的本征腐蚀速率排序为掺S晶片>掺Fe晶片>非掺杂晶片>掺Zn晶片。研究晶片损伤层对翘曲度的影响时应结合晶体各向异性。利用Stoney公式,结合InP单晶加工应力特性,分析了损伤层厚度与晶圆翘曲度的关系。研究结果表明,由于[001]晶片表面各区域的加工性能呈现出较强的各向异性,造成表面损伤状态也呈现同样的规律,导致切割片呈现“马鞍”状。最后提出了如降低加工应力、优化腐蚀方案等降低InP切割片翘曲度的有效途径。

簇生番茄果梗超声切割过程仿真与试验

为揭示超声技术应用于簇生番茄切割采收的机理及优势,比较了簇生番茄果梗材料在常规切割和超声切割中的切割力和去除特性。首先测定了簇生番茄果梗和自制超声切割刀的参数,然后基于Abaqus进行仿真,将果梗纤维化,在宏观和微观仿真中对比常规切割和超声切割过程中的应力及去除机理。最后,自制试验台,通过改变超声切割刀的激振频率、输入电压、切割速度和切割角度进行切割力测定试验并采用响应面法的Box-Behnken进行四因素三水平分析,随后观察果梗断面形貌。结果表明:在自制超声刀工作频率(35~37 kHz)和电压(340~380 V)内,切割速度、角度对切割效果影响最显著,激振频率和输入电压在特定值附近时切割效果最好;在36 kHz、360 V、0.125 cm/s、0°的条件下,仿真中超声切割耗时约为8 s,平均最大切割力为0.635 N,相对于常规切割(1.019 N)降低37.7%;试验中超声切割耗时约为5.3 s,所需切割力最大为0.543 N,相较于常规最大切割力(1.017 N)降低46.6%,同时表面粗糙度降低20.9%,试验与有限元仿真的切割力结果误差为8.9%,基本吻合。超声切割可以降低切割力,缩短切割耗时,同时还提高断面质量,减少果梗组织损伤、水分散失,对延长果实保鲜时间具有一定的意义。

ITO导电玻璃单颗磨粒切削机理仿真试验研究

为研究氧化铟锡(indium tin oxide,ITO)导电玻璃材料的去除机理,采用单磨粒对材料进行切削仿真,建立了ITO导电玻璃的材料模型,根据加工表面形貌、应力和切削力情况分析了材料去除机理,之后研究了切削参数对切削力和残余应力的影响,并与钠钙玻璃进行对比分析。结果表明:在磨粒的切削过程中,材料的去除受ITO薄膜层、玻璃基底和内聚力接触行为的共同影响,会产生分层、通道开裂和层间断裂等失效形式;随着磨粒的进给,切削力在一定范围内波动,且呈现上升、稳定、降低的变化,同时磨粒的切削力与切削速度和切削深度呈正相关;薄膜上残余应力相比玻璃基底,数值更大且波动更剧烈;当切削深度接近ITO薄膜厚度时,薄膜的存在对磨粒切削行为的影响显著。

不对行大蒜联合收获机设计与试验

现有大蒜联合收获机主要采用振动挖掘、对行夹持输送、自动切茎方式,这种收获方式要求大蒜种植时要对行播种,同时在收获过程中机具要尽量对行直线行驶,否则极易因对行不准而发生漏收、堵塞等问题。针对这一情况,设计一款可不对行收获的大蒜联合收获机。首先,基于不对行收获的特点和大蒜收获的农艺要求,进行整机总体设计;其次,通过建立数学模型完成灭茬机构设计和选型,建立运动学模型确定蒜秧切割机构和振动挖掘机构的运动参数;最后,以前进速度、入土倾角和挖掘深度为试验因素,以损伤率和漏收率为主要评价指标,进行三因素三水平正交组合试验并利用SPSS软件进行方差分析。结果表明:当前进速度为0.35 m/s,入土倾角为20°,挖掘深度为100 mm时,不对行大蒜联合收获机性能最优,此时损伤率为2.91%、漏收率为3.93%。

单颗CBN磨粒超声振动辅助磨削AISI 304材料去除机理

为了解释超声作用下磨粒切削材料的去除机理,对单粒磨削过程进行了分析,建立了未变形切削厚度和磨粒与试件的固定速度比(vs/vw)的数学模型.在AISI 304试件上进行了固定速度比的普通磨削(conventional grinding,CG)、切向超声振动辅助磨削(tangential ultrasonic vibration assisted grinding,TUVAG)以及径向超声振动辅助磨削(radial ultrasonic vibration assisted grinding,RUVAG)的单颗粒试验.结果表明,在固定速度比条件下,试件在CG与TUVAG作用下都是以塑性变形的形式去除,但超声辅助显著提高了材料去除率.试件在RUVAG作用下材料的去除方式与未变形切削最大厚度agmax的值息息相关.agmax小于0.8μm时,试件表现为脆性断裂的形式去除;之后随着agmax逐渐增大,试件转变为塑性变形的形式去除.

悬臂式掘进机整机测试系统

介绍了在掘进装备新发展形势下,太原煤科院建立了新的悬臂式掘进机整机测试系统,该系统包括:掘进装备整机截割试验装置、可调断面模拟巷道、坚固型多通道动态数据采集装置、液压系统动态测试仪、整机运行参数分析装置以及大处风量干式除尘装置,并对每种装置的关键技术进行了叙述。形成的整机测试系统可为我国现有掘进机进行全方面的测试,为我国掘进机的发展提供了基础理论和试验支持。

Crystallographic orientation effect on cutting-based single atomic layer removal

The ever-increasing requirements for the scalable manufacturing of atomic-scale devices emphasize the significance of developing atomic-scale manufacturing technology. The mechanism of a single atomic layer removal in cutting is the key basic theoretical foundation for atomic-scale mechanical cutting. Material anisotropy is among the key decisive factors that could not be neglected in cutting at such a scale. In the present study, the crystallographic orientation effect on the cutting-based single atomic layer removal of monocrystalline copper is investigated by molecular dynamics simulation. When undeformed chip thickness is in the atomic scale, two kinds of single atomic layer removal mechanisms exist in cutting-based single atomic layer removal, namely, dislocation motion and extrusion, due to the differing atomic structures on different crystallographic planes. On close-packed crystallographic plane, the material removal is dominated by the shear stress-driven dislocation motion, whereas on non-close packed crystallographic planes, extrusion-dominated material removal dominates. To obtain an atomic, defect-free processed surface, the cutting needs to be conducted on the close-packed crystallographic planes of monocrystalline copper.

2.5D C/SiC复合材料铣削材料去除的实验研究

为了探究2.5D C/SiC复合材料铣削加工的材料去除特性,分别选用端铣刀和鱼鳞铣刀对2.5D C/SiC复合材料开展普通铣削和超声振动辅助铣削实验。分析了四种铣削工况下切削力、切削温度的变化规律,研究了0°、90°和z向针刺纤维的去除特性。结果表明,相比于传统端铣刀和普通铣削,鱼鳞铣刀和超声振动辅助铣削分别可以显著地降低切削力和切削温度。超声振动辅助铣削可以使纤维的整体去除变为破碎去除,减小表面缺陷。鱼鳞铣刀和超声振动辅助铣削的组合工艺方式可以较大程度地降低表面缺陷、切削力和切削温度,提高工件表面质量,为2.5D C/SiC复合材料低损伤铣削提供了可行性。