面向工程陶瓷的单颗金刚石磨粒划擦磨损规律

为了研究工程陶瓷平面磨削中金刚石砂轮的磨粒磨损规律,制备圆锥形单颗粒金刚石磨具模拟实际磨粒切削刃。以金刚石磨粒的尖端圆弧半径表征磨粒切削刃锋利程度与磨削能力,并用圆弧半径的磨损规律等效描述切削刃磨损特性。采用基于扫描电镜与数据拟合的技术测量单颗磨粒金刚石尖端圆弧半径。运用单因素试验及正交试验分析了金刚石颗粒尖端形状、材料种类与加工参数对磨粒磨损规律的影响。实验结果表明,当顶锥角2θ为120°、磨削深度ap0.01 mm时,金刚石磨粒具有较高划擦寿命。各因素的影响主次顺序为:顶锥角>磨削深度>工作台速度。本研究为金刚石砂轮磨粒规格和磨削用量的选取提供了重要参考。     

超硬磨具磨粒有序排布技术的原理及应用

磨料有序排布的超硬磨料工具是磨削工具家族的新品种,其工作表面具有按一定规律整齐排布的磨削刃,与传统磨具相比具有容屑空间大、磨削刃锋利、磨削力小和磨削温度低等优点,目前已经成功应用于高效精密磨削加工领域,并表现出良好的应用潜力。但如何实现磨粒高效率和精确的有序排布还是一个难题,因此迫切需要发展新的磨粒排布技术。文章介绍了有序排布磨料的基本理论,磨具的构造、主要制造方法以及研究发展情况,分析了排布方式对磨削性能的影响,并对其今后的发展方向进行了展望。      

钎焊金刚石磨削石材过程中磨粒磨损状态研究

通过数字视频采集系统跟踪观察钎焊金刚石砂轮磨削过程中磨粒表面形貌变化.研究了钎焊金刚石砂轮在磨削花岗石材料过程中,金刚石磨粒的出刃高度和磨损状态的变化规律.结果表明,钎焊金刚石工具在加工过程中,钎焊金刚石磨粒可分为六种磨损状态:完整晶形、微观破碎、宏观破碎、磨平、折平和脱落.磨粒磨损路径主要是以完整→微观破碎→宏观破碎→脱落的方式进行.金刚石磨粒在磨损过程中,可分为初期磨损、正常磨损和剧烈磨损三个阶段.     

微粉金刚石表面镀钛对钎焊磨具性能的影响

在微粉金刚石磨具的制备过程中,金刚石热损伤和磨粒与结合剂间界面特性是影响磨具性能的主要因素。利用电铸与钎焊相结合的工艺把表面镀钛和未镀钛两种微粉金刚石磨料制备成磨具,并将其用于氧化铝陶瓷的磨削试验。通过对钎焊后金刚石磨粒与钎料的界面分析,磨削力、磨粒脱落率以及工件表面粗糙度的比较,探讨磨粒表面镀钛对钎焊微粉金刚石磨具性能的影响。结果表明,镀钛微粉金刚石表面镀层在钎焊过程中对微粉金刚石起到包裹隔离的作用,可以降低微粉金刚石的热损伤和石墨化;在利用两种钎焊微粉金刚石磨具磨削氧化铝陶瓷时,镀钛微粉金刚石磨具的磨削力较小,磨料的脱落率也较少,且工件表面粗糙度值更低。综合比较,磨粒表面镀钛后,可以减弱微粉金刚石的热损伤,提高磨具的磨削性能。     

改性树脂立方氮化硼磨具力学性能的研究

以改善钛合金磨削高温和磨具黏附问题为研究目的,通过在树脂CBN(立方氮化硼)磨具中添加不同量的六方氮化硼(HBN)作为固体润滑剂,并对样品进行力学性能测试,以探究不同添加量对磨具磨削性能的影响及钛合金磨削高温和磨具黏附的改善情况。经测试,在HBN添加量为8 g的树脂磨具样条中,磨粒出刃效果好,结合剂黏结磨粒的强度较好,失去磨削效果的磨粒脱落及时。     

钎焊金刚石砂轮高速磨削氧化铝陶瓷的磨损特征

利用真空炉中钎焊工艺制作了钎焊金刚石砂轮,并对氧化铝陶瓷进行高速磨削的磨损研究.实验中,监测了磨削过程中每道磨削的磨削力特征,观察和统计了不同磨削阶段的砂轮表面磨粒磨损状态及变化情况,同时测量了磨粒的出刃高度.结果表明:在高的砂轮线速度和高的材料磨除率下,容易造成大量的磨粒断裂和完全破碎.仅有1.23％的金刚石磨粒是经历“完整-磨平—微破碎—半破碎—断裂(全破)”的失效过程,即磨粒理想的失效路径.通过对钎焊工艺、磨粒承受的载荷以及砂轮表面磨粒浓度和排布方式等因素的分析,阐明了文中钎焊金刚石砂轮中磨粒失效的原因.     

金属结合剂#600金刚石砂轮的接触放电修锐实验研究

针对微细金刚石磨粒很难从金属结合剂砂轮的胎体中出刃的问题，开发出一种新修锐方法一接触放电修锐、它采用一种旋转复合电极修整轮与砂轮接触磨削，在金属结合剂胎体与电极间产生微小的脉冲放电，逐渐去除砂轮的金属结合剂，使微细金刚石在砂轮工作表面出刃，达到精密修锐的目的。通过对金属结合剂#600金刚石砂轮进行修锐实验，研究其有效性、修锐条件和实际应用。实验表明，该修锐方法不仅不损伤微细金刚石磨粒出刃刃角，而且还可以消除磨粒周围的结合剂尾状物，产生较好的容屑空间。磨削光学玻璃(BK10)的试验结果显示它比机械修锐能够更好地提高磨削表面质量，Ra达到0．12μm。     

低刚度约束下复合材料螺旋铣磨制孔

针对复合材料构件空间狭小、加工可达性差、加工精度不足的问题,使用基于微刃切削原理的电镀金刚石磨具,在低刚度约束下螺旋铣磨制孔。通过理论分析磨粒切削长度和实验对比加工效果,发现:相较于普通硬质合金刀具,金刚石磨具的磨削力峰值降低30%,且普遍低于60 N;用金刚石磨具加工的孔边缘几乎无毛边,也不见磨削烧伤。采用微刃切削方法可降低切削力,减少加工毛刺,提高加工精度。      

金刚石砂轮磨削氮化硅陶瓷数值仿真及实验研究

针对金刚石砂轮磨粒的尺寸多变化、位置不规则的特点,通过切割正四面体的方法,获得了接近实际的十四面体磨粒模型,并通过其建立了金刚石砂轮模型。采用DEFORM-3D进行金刚石砂轮磨削氮化硅陶瓷数值仿真,分析工件的切屑去除过程以及其间的切削力变化,并分析不同的工艺参数对切削力的影响;同时,在平面磨床上进行磨削氮化硅陶瓷的实验。结果表明:磨削加工和数值仿真的磨削力值变化趋势相同,且差值在10%的误差范围内。最后,结合实际砂轮表面面积密度、磨粒平均个数、出刃高度等测量参数,共同验证了所建立的十四面体磨粒模型和砂轮整体模型的正确性。     

钎焊单层金刚石磨具的研究进展

钎焊单层金刚石磨具的研究和应用在国内外越来越受重视,与电镀单层金刚石磨具相比,钎焊单层金刚石磨具具有金刚石出刃高、容屑空间大、金刚石与基体之间的结合强度高等无可比拟的优点。从钎焊机理、钎料选择和钎焊工艺流程三方面介绍国内外钎焊单层金刚石磨具的研究现状,并分析大批量制造单层金刚石磨具存在的问题,指出下一步的研究有四项关键技术值得关注:钎料厚度的实用化控制、优质钎料的开发、钢基体受热变形、金刚石磨粒有序排布技术,为钎焊单层金刚石磨具的产业化提供借鉴。     

Study on micro-topographical removals of diamond grain and metal bond in dry electro-contact discharge dressing of coarse diamond grinding wheel

A coarse diamond grinding wheel is able to perform smooth surface grinding with high and rigid grain protrusion, but it is very difficult to dress it. Hence, the dry electro-contact discharge (ECD) is proposed to dress #46 diamond grinding wheel for dry grinding of carbide alloy. The objective is to understand micro-topographical removals of diamond grain and metal bond for self-optimizing dressing. First, the pulse power and direct-current (DC) power were employed to perform dry ECD dressing in contrast to mechanical dressing; then the micro-topographies of diamond grains and metal bond were recognized and extracted from measured wheel surface, respectively; finally, the relationship between impulse discharge parameters and micro-topographical removals was investigated with regard to grain cutting parameters, dry grinding temperature and ground surface. It is shown that the dry ECD dressing along with spark discharge removal may enhance the dressing efficiency by about 10 times and dressing ratio by about 34 times against the mechanical dressing along with cutting removal. It averagely increases grain protrusion height by 12% and grain top angle by 23%, leading to a decrease 37% in grinding temperature and a decrease 46% in surface roughness. Compared with the DC-25V power along with arc discharges, the Pulse-25V power removes the metal bond at 0.241 mm³/min by utilizing discharge energy by 73% and diamond grain at 0.013 mm³/min through surface graphitization, respectively, leading to high and uniform grain protrusion. It is confirmed that the impulse discharge parameters are likely to control the microscopic grain protrusion topography for efficient dressing according to their relations to the micro-removal of metal bond.     

电镀cBN砂轮油石修整效果及评价研究

针对电镀砂轮制造过程中存在的磨粒等高性不好的问题,采用白刚玉油石对其进行修整。通过选择合理的修整参数,使得砂轮和油石的相互作用力控制在一定的范围内,实现突出高度较高,结合强度差的磨粒的去除;而对等高性较好,结合强度较高的磨粒影响不大,从而达到修整的目的。为了对修整效果进行评价,采用激光扫描方法得到修整前后砂轮的地貌,并根据地貌的不同特征分析和验证修整效果,重点关注磨粒出刃高度和等高性。     

金属结合剂金刚石砂轮的修整研究(Ⅰ)——用立体照片对测量磨粒的突出高度及磨粒突出高度对磨削性能的影响

金属结合剂金刚石砂轮的磨粒突出高度极大地影响砂轮的磨削性能。磨粒突出高度大小容易导致砂轮堵塞从而使磨削力增大;磨粒突出高度太大则容易导致磨粒脱落从而使砂轮磨损加快。然而,迄今为止,精确测量磨粒突出高度的方法尚未见诸报道。本文提出了一种用立体照片对测量磨粒突出高度的方法,即所谓“3D法”,并对磨削Si_3N_4时,磨粒突出高度对砂轮磨削性能的影响进行了实验研究。砂轮的修整用杯形砂轮修整器完成。主要结论如下:(1)砂轮表面修整后,磨粒突出于金属结合剂基面,并且在磨粒后方存在一三角洲状结合剂残留物。磨粒突出高度分布近似为正态分布。(2)磨削力随磨削次数单调增加。(3)通过研究磨削力、工件表面粗糙度及砂轮磨损同磨粒突出高度的关系,对最佳磨粒突出高度进行了一些讨论。     

3D laser investigation on micron-scale grain protrusion topography of truncated diamond grinding wheel for precision grinding performance

A grain tip (GT) truncation is proposed to truncate grain protrusion tips of #270 diamond grinding wheel in plunge grinding of hard and brittle material. In this study, a 3D laser microscopy was employed to measure the wheel working surface and parameterize its 3D grain protrusion topography. The objective is to investigate how micron-scale grain protrusion parameters influence grinding performance such as grinding force and surface roughness. First, the GT truncation was performed after dressing of diamond grinding wheel in grinding experiment of quartz glass; then its 3D grain protrusion topography was constructed by smoothing 3D measured noise, matching measured point cloud, transferring protrusion frame and extracting 3D diamond grains; finally, the grain protrusion parameters such as grain protrusion number, grain protrusion height, grain protrusion volume, grain rake angle, grain clearance angle, etc. were investigated in connection with ground surface and grinding force. It is shown that GT truncation averagely decreases grain protrusion number, grain protrusion height, grain protrusion volume, grain rake angle and grain clearance angle by about 44%, 74%, 75%, 24% and 70% on whole wheel surface, respectively. However, it greatly increases active grain number by about 32 times and active grain volume by about 181 times in actual grinding with the depth of cut in 1 μm, thus leading to a decrease (about 80%) in surface roughness and an increase (about 40 times) in grinding force. It is also found that truncated diamond grain tips are mostly shaped with nanometer-scale tip wedges along grain cutting direction, leading to about 75% very large negative grain rake angles and about 75% large grain clearance angles, thus contributing to ductile-mode grinding. It is confirmed that the active grain number and active grain volume for the actual depth of cut may be regarded as main grain protrusion parameters to evaluate and predict the precision grinding performance of a coarser diamond grinding wheel.     

钎焊金刚石砂轮修整实验研究

单层钎焊金刚石砂轮的圆度轮廓精度由于受磨料粒径和钎焊结合剂层高度不均匀等因素的影响而使其难以在工程陶瓷等硬脆材料精密磨削中应用.然而单层钎焊金刚石砂轮的修整是直接对金刚石磨粒进行微量的磨损,修整难度大、效率低,因此,探讨快捷且精密的整形方法就成了解决其应用问题的关键技术之一.在本文研究中,分别采用铁基金刚石烧结磨块、钎焊细粒度金刚石板和氧化铝磨块三种整形工具对钎焊金刚石砂轮进行了磨削法整形实验研究,实验结果表明利用氧化铝磨块进行磨削修整效率极低;钎焊金刚石板磨削修整虽然效率高,但是对砂轮表面金刚石磨粒造成大量破碎磨损;铁基金刚石烧结磨块在整形过程中可稳定地以磨平方式磨损砂轮表面金刚石磨粒,经精密整形后的砂轮圆度轮廓精度较高,用其磨削工程陶瓷时工件表面的犁沟和裂纹明显减少.     

Study on axial-feed mirror finish grinding of hard and brittle materials in relation to micron-scale grain protrusion parameters

An axial-feed mirror finish grinding of hard and brittle materials is proposed by controlling grain protrusion parameters. In this grinding, the grinding wheel feed is along the wheel axial direction rather than in the traditional wheel cutting direction. The objective is to understand how micron-scale grain protrusion parameters influence ductile-mode grinding and ultimately to realize efficient mirror finish grinding using a coarse diamond grinding wheel. In this study, the grain tip truncation (GT-truncation) was performed after dressing to improve grain protrusion topography. First, a formation model of axial-feed ground surface was constructed to analyze the effect of grain protrusion parameters and grinding parameters on the critical cutting depth transferred from brittle-mode removal to ductile-mode removal; then GC dressing and GT-truncation of #180 diamond grinding wheel were experimentally performed to investigate surface roughness and ductile-mode grinding behavior with reference to grinding parameters and grain protrusion parameters; finally, a truncated coarser #60 diamond grinding wheel was employed for mirror finish grinding to observe active grain number and grain protrusion angle. Theoretical analysis shows that this ductile-mode grinding is dominated by active grain number, active grain protrusion angle, wheel rotating speed and axial-feed speed, but it does not depend on the depth of cut assumed to be less than the grain protrusion height. Experimental results indicate that the GT-truncation may increase active grain number and grain protrusion angle for ductile-mode grinding when the axial-feed speed decreases to some extent. Moreover, the micro tip radius of diamond grain also influences the ground surface. It is confirmed that by increasing active grain number and grain protrusion angle synchronously, a truncated #60 diamond grinding wheel can be applied for efficient mirror finish grinding of the SiC ceramic plate at the axial-feed speed of 50 mm/min and the tool path interval of 0.1 mm.     

面向快速制造车身模具的机器人软质工具研磨工艺研究

在研究以硬质工具进行机器人自动研磨的基础上。建立了采用软质工具的机器人自动研磨系统。根据被研磨工件的表面形状，对研磨轨迹进行了规划。以机器人研磨系统为平台，进行了基础工艺实验，分析了主轴转速、机器人行走速度、横向进给量等工艺参数对研磨质量的影响，从而综合选择合适的工艺参数，并进行相应的误差补偿。通过实验确定了合理的预压量，并进行了等离子熔射制造的车身模具表面研磨试验，得到了较好的研磨效果。     

金属结合剂金刚石砂轮的修整研究(Ⅱ)——修整金属结合剂金刚石砂轮的机理

在上一篇文章中。笔者提出了一种新的测量磨粒突出高度的方法,并就磨粒突出高度同砂轮磨削性能的关系进行了研究。本文探讨了结合剂密实型金刚石砂轮的修整机理,着重讨论修整时磨粒周围结合剂的会除过程。证明了去除结合剂的机制是杯形砂轮上脱落下来的GC磨粒的研磨作用。主要结论如下:(1)修整时,GC磨粒从杯形砂轮上脱落并研磨结合剂,从而产生修整效果。因此,杯形砂轮修整器在对金属结合剂金刚石砂轮进行整形的同时,也对其进行修锐。(2)控制冷却液流量使GC砂轮表面附有一层游离磨粒,可以使修整比最高。(3)只要修整次数足够多,平均磨粒突出高度只取决于修整条件。(4)游离GC磨粒的尺寸越大,研磨作用越强,因此修整比越高,平均磨粉突出高度越大。     

精密冲模零件的高精度磨削加工

介绍了高精度磨削加工的关键技术,把高性能、高精度磨削机床、最佳的加工工艺技术与工件材料相适应的砂轮选择技术有机地结合起来,可以提高精密冲模零件的加工精度和凸模的使用寿命。可避免使用传统光学曲线磨床加工精密零件时由于多次定位导致的零件形位精度被超差、磨削加工周期长、成本高等问题。