Efect of Micro Abrasive Slurry Jet Polishing on Properties of Coated Cemented Carbide Tools

Owing to the popularization of coating technology, physical Vapor Deposition (PVD) coated tools have become indispensable in the cutting process. Additionally, the post-treatment of coated tools applied to industrial production can efectively enhance the surface quality of coating. To improve the processing performance of coated tools, micro abrasive slurry jet (MASJ) polishing technology is frst applied to the post-treatment of coated tools. Subsequently, the efects of process parameters on the surface quality and cutting thickness of coating are investigated via single-factor experiments. In the experiment, the best surface roughness is obtained by setting the working pressure to 0.4 MPa, particle size to 3 μm, incidence angle to 30°, and abrasive mass concentration to 100 g/L. Based on the results of the single-factor experiments, combination experiments are designed, and three types of coated tools with diferent surface qualities and coating thicknesses are obtained. The MASJ process for the post-treatment of coated tools is investigated based on a tool wear experiment and the efects of cutting parameters on the cutting force and workpiece surface quality of three types of cutting tools. The result indicates that MASJ machining can efectively improve the machining performance of coated tools.

Approach for Polishing Diamond Coated Complicated Cutting Tool: Abrasive Flow Machining(AFM)

Lower surface roughness and sharper cutting edge are beneficial for improving the machining quality of the cut?ting tool, while coatings often deteriorate them. Focusing on the diamond coated WC?Co milling cutter, the abrasive flow machining(AFM) is selected for reducing the surface roughness and sharpening the cutting edge. Comparative cutting tests are conducted on di erent types of coated cutters before and after AFM, as well as uncoated WC?Co one, demonstrating that the boron?doped microcrystalline and undoped fine?grained composite diamond coated cutter after the AFM(AFM?BDM?UFGCD) is a good choice for the finish milling of the 6063 Al alloy in the present case, because it shows favorable machining quality close to the uncoated one, but much prolonged tool lifetime. Besides, compared with the micro?sized diamond films, it is much more convenient and e cient to finish the BDM?UFGCD coated cutter covered by nano?sized diamond grains, and resharpen its cutting edge by the AFM, owing to the lower initial surface roughness and hardness. Moreover, the boron incorporation and micro?sized grains in the underly?ing layer can enhance the film?substrate adhesion, avoid the rapid film removal in the machining process, and thus maximize the tool life(1040 m, four times more than the uncoated one). In general, the AFM is firstly proposed and discussed for post?processing the diamond coated complicated cutting tools, which is proved to be feasible for improving the cutting performance

Machining of the Flat Surfaces with Abrasive-metallic Lapping Tools

The constructional principle of abrasion metal disc is that abrasive insertions are spread uniformly on the working surface of a metal base. During lapping by means of such tools only the machining fluid is dosed and that by drop. Abrasive elements of circular shape pellets are produced by mixing boron carbide BC400 micrograins with electrographite components, the pellets were pressed with a load of about 12 kN. Next they were heated in furnace at about 520K for hours, then cooled together with the furnace. Tests were carried out on the making of circular abrasive insertions of which the main components were born carbide and micrograins of electric copper mixed the epoxide resins.

油气井井下切割技术发展现状及趋势

油气开发后期,退役井数量急剧增加,完井修井作业中套管磨损、卡钻等问题突出,退役经济耗费显著增加。为最大限度减少卡钻和退役经济耗费,有必要开展新型套管切割技术及装备的研发与应用。首先,总结了现阶段井下管柱切割技术的主要类型、工作原理和配套装备,包括机械切割、磨料射流切割、聚能切割、化学切割、电弧切割以及激光切割;对比机械切割、磨料射流切割以及特种切割方式的技术发展现状和趋势,分析上述切割方式的工程应用及优缺点;在此基础上,提出面向高效套管切割工程需求的主要切割技术及工具。结合目前切割技术及工具的发展现状,对未来井下管柱切割技术给出优化割刀性能、加强磨料射流切割的控制、研制新型切割工具及切割工具智能化等建议。

磁弹磨粒对刀具冲击特性仿真分析

磁弹磨粒因其低弹性可在加工时产生弹性变形而减轻对工件的冲击和划伤,成为了抛光和研磨表面精加工领域的热门材料。基于双磁盘磁力刀具钝化方法,探究磁弹磨粒的几何形状对硬质合金刀具材料冲击特性的影响。首先,通过仿真软件ABAQUS建立磨粒冲击刀具模型并进行仿真;其次,通过仿真分析磨粒冲击速度、几何形状等对应力应变、冲击深度和冲击过程中的能量转移等的影响规律。结果表明,同条件下锥体磨粒对刀具造成的最大应力、冲击深度值皆比球体磨粒的大,且随着锥体磨粒锥角的增大,刀具受到的最大应力呈减小趋势。

基于反刍类动物臼齿仿生的平面磨具形貌结构设计与性能研究

目的 提高平面研磨加工效率及加工质量。方法 提取了反刍类动物臼齿齿面形貌特征,设计了一种模块化分布式平面研磨工具,采用ABAQUS分析了无特征规则排布磨具与仿生特征排布磨具在研磨抛光过程中对工件压力分布均匀性的影响;采用Fluent分析了仿生特征排布磨具形貌结构对磨削液流动性的影响;利用3D打印技术制备了仿生特征排布磨具与无特征规则排布磨具并进行了对比实验,通过响应面分析法讨论了转速、压力、表面结构特征等因素对磨具研磨性能的影响。结果 仿真结果表明,与无特征规则排布磨具相比,在4 N研磨压力下仿生特征排布磨具具有更优的工件表面应力分布均匀性;磨削液在磨具形貌特征间隙入口的流速为2.400 m/s时,与其他特征磨具相比,仿生特征模块化排布磨具的形貌特征间隙出口平均流速提升了29.45%。实验结果表明,与无特征规则排布磨具相比,在同等工艺下,使用仿生特征模块化排布磨具研磨的铝合金试件表面粗糙度由0.301μm降至0.188μm,下降了17.94%;当研磨压力为5 N时,材料去除速率由1.44μm/min提升至1.93μm/min,提升了34.47%。结论 平面磨具的形貌结构特征设计与排布对研磨过程中的工件接触压力分布、磨削液流动性具有重要影响。与无特征规则排布磨具相比,在相同工艺条件下臼齿仿生特征模块化排布磨具能够更有效地提升加工效率及加工质量。

磁弹磨粒几何特征对刀具刃口的影响研究

针对双磁盘磁力刀具钝化中磁弹磨粒的不规则形状、不确定尺寸等几何特征,仿真研究了磁弹磨粒几何特征对刀具刃口材料去除的影响。基于ABAQUS有限元仿真软件建立磁弹磨粒冲击刀具刃口模型并进行仿真,分析磁弹磨粒冲击角度、几何特征等参数对刀具刃口的应力应变、冲击深度和冲击过程中能量转换的影响规律。

基于双磁盘刀具钝化中磁弹磨粒的磨损及寿命研究

为了探究磁弹磨粒在双磁盘刀具钝化中磨损规律以及使用寿命的长短,通过对磁弹磨粒进行受力分析讨论了其磨损失效的形式,得出了影响磁弹磨粒寿命的主要因素。然后,制备出不同质量配比和不同磨粒相类型的磁弹磨粒,采用双磁盘钝化设备进行钝化实验,分析了磁弹磨粒质量配比和磨粒相类型对磁弹磨粒的磨损规律和对刃口表面粗糙度的变化规律,同时还对钝化前后的磁弹磨粒进行X射线能量色散普(EDS)和激光粒度分析。实验结果表明,以氧化铝为磨粒相的磁弹磨粒在钝化过程中主要发生磨粒相磨钝磨损,以金刚石为磨粒相的磁弹磨粒主要发生磨粒相脱落磨损,两种类型的磁弹磨粒都是在质量配比3:1时使用寿命最好。

弹性基体软固结磨料磨具的材料去除机理

基于弹性磨具的磨抛工艺为硬脆材料超精密加工效率与加工质量的兼顾平衡提供了新的解决思路,但其磨抛过程的材料去除机理尚未明确。为研究弹性磨抛过程中的材料去除行为,以硅橡胶作为磨具基体材料,混合微米级金刚石磨料制备弹性基体软固结磨料磨具,利用有限元仿真分析方法研究弹性基体软固结磨粒的受力状态,结合接触力学与运动学分析建立考虑单颗磨粒磨损行为与有效磨粒数量的材料去除模型,通过石英玻璃试件的弹性磨抛加工试验验证预测模型的准确性。结果表明:石英玻璃试件的材料去除率随着磨抛压力、主轴转速、磨具偏角的增大而显著增加,而磨料粒径对其影响程度较小;当工艺参数组合为磨料粒径100μm、磨抛压力7 N、主轴转速1500 r/min、磨具偏角20°时,经60 min磨抛后,工件已加工表面粗糙度由1.069μm降至0.089μm,材料去除率为8.893×10^(8)μm^(3)/min;该试验条件下,建立的材料去除模型预测准确度相比Preston经典模型提高36.7%。研究成果可为实现硬脆材料的确定性材料去除提供技术支持和理论依据。

不同刀具钝化方法加工硬质合金立铣刀刃口的对比试验研究

为改善刀具性能、提升加工质量,采用旋转磨粒流对刀具钝化。通过对比立式旋转钝化法和旋转磨粒流钝化法钝化硬质合金立铣刀的效果,研究刀具刃口变化规律。试验结果表明:未钝化的刀具刃口半径值最小,且存在很多缺陷,刃型呈尖锐形;立式旋转钝化法得到的刃口半径值变化较小,但刀具刃口缺陷仍然存在,刃型呈不均匀的钝圆形;旋转磨粒流钝化法处理后的刃口半径值变化最大,去除了部分刃口缺陷,刃型呈均匀的钝圆形。旋转磨粒流钝化法不仅可以更好地去除刀具刃口的表面缺陷,同时有着更高的钝化效率以及刃口半径变化率,可以显著提高刀具性能,降低刀具磨损并改善加工质量。

不同类型磁弹磨粒对刀具钝化的研究

为研究不同类型磁弹磨粒对刀具钝化的影响,分别以硅胶和环氧树脂为黏弹性基体、氧化铝(Al_(2)O_(3))颗粒为磨粒相、铁颗粒为磁粒相制备出硅胶型磁弹磨粒和环氧树脂型磁弹磨粒;基于双磁盘的磁场特性,采用Maxwell软件建立双磁盘磁场的三维模型,对双磁盘磁场及磁弹磨粒的磁场强度和磁感应强度进行分析;并建立磁弹磨粒细观单元模型,运用ABAQUS软件分析2种磁弹磨粒的细观力学特性;最后,基于双磁盘磁力钝化设备,研究2种磁弹磨粒对刀具钝化的影响。实验结果表明:采用环氧树脂型磁弹磨粒钝化后的刀具刃口表面粗糙度值比硅胶型磁弹磨粒钝化后的刀具刃口表面粗糙度提高了约4.2%,且刀具刃口形貌更为规则。

金刚石砂轮盘轮廓精度检测及盘面精密修整方法

金刚石砂轮盘的轮廓精度检测及盘面精密修整是金刚石刀具制造领域的关键问题。首先为实现砂轮盘轮廓误差的高精度测量,提出一种基于激光三角测量的在位测量方法,实现了砂轮盘面误差亚微米级精度的高效检测。实验结果表明,该方法可以方便地评估不同精修参数下的修整精度。随后,采用单点金刚石修整法对青铜基金刚石砂轮盘进行了盘面精密修整工艺实验,分别探究了修整进给深度、主轴转速、主轴往复运动频率以及修整压力对盘面修整精度的影响,并优选了修整工艺参数,优选的工艺参数为:修整深度1µm,主轴转速3000r/min,主轴往复频率0.15Hz,接触压力14.7N。最后,不同修整精度的砂轮盘分别被用于研磨金刚石微楔形刀具。实验结果表明,所提出的砂轮盘精度检测和盘面精密修整方法对提高金刚石刀具的制造质量具有重要应用价值。

Experimental study on the working performance of different milling tools for multistage fracturing ball seats

To achieve the secondary production in multistage fracturing wells of tight oil,milling tools are usually used to remove the multistage fracturing ball seats to achieve production with a large diameter in later.In this paper,first of all,the working mechanism of milling tools for multistage fracturing ball seats was studied and a mechanical analysis model of single abrasive grain was established.Then,an experimental system for milling tools was developed,and the experimental tests of the flat,the blade,and the slope milling tool were conducted in order.Besides,the morphology of chips and the surface morphology of the workpiece after the experiment were analyzed.Also,the working performance of milling tools was evaluated from the perspectives of working safety,working efficiency,and wear resistance of the milling tool.The results show that the torque of the milling tool increases nonlinearly with the increase in the cutting depth of the abrasive grain and increases linearly with the increase in the cutting width.Also,the chips are irregular particles and the size is mainly from 10 to 50μm.So,the chips should be pumped up with a small pump pressure and a large displacement.Besides this,the cutting depths of the abrasive grains are from 216.20 to 635.47μm and the bottom surface of the milling tool should be eccentric to avoid the zero point of cutting speed.Furthermore,the torque of the slope milling tool is 23.8%larger than that of the flat milling tool,which is also 30.4%smaller than that of the blade milling tool.Compared with the flat milling tool,the working efficiency of the blade milling tool improves by 79.9%and the slope milling tool improves by 111.1%.Also,the wear resistance of the blade milling tool decreases by 102.7%,while the slope milling tool declines by 32.6%when compared with the flat milling tool.Therefore,the slope milling tool has the characteristics of moderate torque,stable working conditions,the highest working efficiency,and fine wear resistance,which is preferably used to mill multistage fracturing ball seats.This study provides a theoretical basis and guidance for milling multistage fracturing ball seats on-site and realizing production with a large diameter in later stages of multistage fracturing wells.

丝锥刀具旋转磨粒流去毛刺和钝化抛光技术

目的高效、低成本地消除丝锥、铰刀、钻头、铣刀等金属加工刀具磨削后产生的表面毛刺、亚表面烧伤等加工缺陷,实现刀具的高效钝化抛光。方法基于磨粒流加工(AFM)技术,提出一种刀具旋转磨粒流抛光(R-AFM)原理和方法。通过模拟仿真方法获得优化的刀具运动轨迹,进一步研发可装夹40把刀具的多工位旋转磨粒流高效抛光专用设备;以高速钢丝锥为研究对象,选用新研制的GC磨料介质作为钝化抛光介质,采用正交实验设计法,通过极差分析和方差分析,探究工件转速、加工时间、磨粒粒径及磨粒质量分数等工艺参数对刃口钝圆半径的影响规律;再选用正交试验获得的工艺参数组合,采用自主研制的WS和GC磨料介质,分别对丝锥刀具进行钝化抛光试验,分析2种新型磨料介质的钝化抛光特性;最后,基于前面的实验结果和理论分析,优选刀具钝化抛光复合加工的工艺参数,并验证刀具的钝化抛光效果。结果各工艺参数对刀具刃口钝圆半径的影响程度依次为刀具回转速度、钝化抛光时间、磨粒质量分数和粒度。高硬度的GC磨料介质具有材料去除率高、对刃口的钝化能力较强等特点。在保持切削刃锋利度的前提下,采用低硬度的WS磨料介质,其毛刺去除效果更好。采用优化的工艺参数和自主研制的WS、GC磨料介质,对新加工的丝锥分别进行了1.5 min和1 min的组合抛光,加工后丝锥表面的毛刺得以完全去除,表面磨削烧伤痕迹显著消减,表面粗糙度Sa可从0.73μm降至0.26μm,刃口圆角半径可控制在企业要求的5μm以内,刃口得到了有效修整,且避免了刀具刃口的“过顿”现象,抛光效率平均可达20支/min。结论旋转磨粒流抛光技术与装备能高效去除刀具表面的毛刺,有效地改善了刃口加工缺陷,为复杂结构成型刀具等零件的高质、高效钝化抛光加工提供了一条新途径。

基于改进LCPC测试方法的盾构隧道土体磨蚀性试验

法国桥梁道路实验室磨蚀性(Labroatoire Central de Ponts et Chaussées,LCPC)试验是测试土体磨蚀性的一种常用方法,但现有LCPC试验在评估盾构隧道土体磨蚀性时存在土体颗粒有效破碎率高、测试过程中颗粒级配变化较大等问题。鉴于此,采用圆形测试钢片替代原有矩形测试钢片,并进行对比试验。结果表明:改进后的圆形测试钢片比原有矩形测试钢片导致的土样颗粒有效破碎率大幅降低,提高了土样在LCPC试验过程中颗粒级配的稳定性;改进后的圆形测试钢片在测试过程中的磨损以磨粒磨损为主,有效剔除了冲击磨损,更符合盾构隧道工程特点;在以磨粒磨损为主时,2种测试条件下的磨损指数(LCPC abrasivity coefficient,LAC)值换算关系为LAC_(矩)=0.93LAC_(圆),其中LAC_(矩)为矩形钢片测试条件下的LAC_(值),LAC_(圆)为圆形钢片测试条件下的LAC值;改进后的试验方法准确评估了北京地铁19号线右安门外站—牛街站区间和大兴国际机场线3#风井—草桥站区间的圆砾卵石地层的磨蚀性。本研究对于提高LCPC试验方法评价盾构隧道土体磨蚀性的准确性提供了重要途径。

磁弹磨粒双磁盘磁力钝化仿真与实验研究

磁弹磨粒具有磁性、低弹性模量以及优良的研磨性能,能够提高加工效率和加工质量。首先,基于磁场基本理论和磁弹磨粒特性,分析了磁弹磨粒双磁盘磁力刀具钝化机制;然后,基于磁场中磁弹磨粒的磁场力对离散元软件EDEM进行二次开发,建立了磁弹磨粒双磁盘磁力刀具钝化过程仿真模型,研究了磨粒粒度、磁化率和磁盘间距对刃口碰撞次数和磨粒旋转速度的影响规律;最后,采用Matlab软件对刀具刃口轮廓进行重建,提出了基于钝化面积的改进形状因子表征方法,通过正交实验研究了磨粒粒度、磁化率和磁盘间距对刃口钝化量的影响规律,并验证了所提改进形状因子表征方法的可行性。结果表明:随着磁弹磨粒粒度的增大、磁化率的增加和磁盘间距的减小,刃口碰撞次数和磨粒旋转速度增大;钝化参数对刃口钝化量的影响程度大小依次为磨粒粒度、磁盘间距、磁化率,最优钝化参数组合为磨粒粒度40目、磁化率0.1、磁盘间距15 mm;仿真与实验钝化面积的最大相对误差为16.33%,最小相对误差为0.42%,仿真能够较好地预测刃口钝化形貌,且改进的刃口形状因子能够较好地表征刀具刃口钝化形貌。

石墨烯对铁基金属结合剂金刚石磨具性能的影响

本文通过调整Fe-Co-Cu-Sn中石墨烯的含量来探究石墨烯对铁基金属结合剂金刚石磨具性能的影响。通过X射线衍射仪、扫描电子显微镜、万能力学试验机等测试了铁基金属结合剂金刚石磨具的显微结构、物相结构、力学性能和物理性能。结果表明:结合剂中石墨烯的含量仅对晶相含量有影响;当石墨烯含量为0.4%(质量分数)时,磨具的抗弯强度最高,为256.0 MPa,较无石墨烯磨具提高了17.4%;随着石墨烯含量增加,石墨烯由片状均匀分布转变为逐渐团聚,断口组织由脆性断裂转变为韧性断裂,磨具的热膨胀系数逐渐降低,导热系数逐渐提高;磨具的磨耗比呈先增加后减少的趋势,当石墨烯含量为0.4%时,磨耗比最高,为199.8,较不添加石墨烯的磨具提高了约21%。

环氧树脂型磁弹磨粒对刀具刃口钝化的实验分析

为探究基于环氧树脂型磁弹磨粒在双磁盘磁场中对刀具钝化的影响,以黏弹性的丙烯酸酯为基体,制备出一种具有导磁性及研磨功能的磁弹磨粒。通过电子显微镜观察环氧树脂型磁弹磨粒形状特征,并测试环氧树脂型磁弹磨粒的密度、硬度和粒度等物理参数,基于磁弹磨粒在双磁盘磁场中对刀具刃口钝化的机制,建立环氧树脂型磁弹磨粒对刀具刃口钝化的实验方案。实验发现,环氧树脂型磁弹磨粒对降低刀具前后刀面的钝化值以及提高刀具刃口表面的粗糙度值都有很明显效果。

CBN超硬磨粒工具的超声振动辅助钎焊结合界面微观组织和力学性能

采用高频感应钎焊方法制备钎焊CBN工具存在钎料层厚薄不均匀、连接界面内部易出现气孔等问题,导致钎料对磨粒的把持强度大幅下降、工具使用寿命显著降低。提出用超声振动辅助钎焊的工艺方法制备钎焊CBN工具,借助超声波在钎焊过程中的空化效应和振荡作用减少钎料合金内部的气孔,同时细化晶粒,以大幅提升磨粒的把持强度。结果表明:相比于普通钎焊工艺,采用超声振动辅助钎焊工艺的钎料合金铺展更均匀,区域内部气孔尺寸变小,相同面积上气孔数量减少了75%,单颗CBN磨粒的剪切力提高了27.7%。通过Ti-6Al-4V钛合金磨削对比试验可知:相比普通钎焊工具,超声振动辅助钎焊工具的法向磨削力降低了4.1%~19.6%,切向磨削力降低了8.3%~26.4%,磨削温度降低了5.3%~17.9%。此外,在相同材料去除体积下,超声振动辅助钎焊CBN工具的磨粒大块破碎现象明显减少,大幅提升了工具的耐磨性和使用寿命。

基于K-Means聚类与凸包检测的金刚石磨粒分割与评价

金刚石工具广泛应用于磨削、线锯、研磨等领域,其表面的磨粒特征是影响加工结果与工具性能的重要因素。针对具有复杂背景信息的磨粒图像,提出一种基于K-means聚类与凸包检测的磨粒分割方法,结合二值化、形态学处理、主轮廓提取等相关操作实现磨粒的提取与分割;最终提出磨粒轮廓面积精度η_(CAA)、磨粒位置误差θ_(PE)和磨粒数量召回率σ_(QR) 3个相关指标来评价分割效果。结果表明:金刚石磨粒的平均轮廓面积精度为95.01%,平均位置误差仅为2.93%,平均数量召回率为98.30%,证明了该方法的准确性。