树脂金刚石砂轮内圆磨削硬质合金工件的试验研究

采用树脂结合剂金刚石砂轮,针对圆筒形硬质合金工件进行内圆磨削试验,研究不同修整工具和修整工艺对砂轮磨削性能的影响,同时对硬质合金磨削用砂轮类型和磨削参数进行了优选。试验结果表明:SiC砂轮及45#钢修整的树脂金刚石砂轮磨削效率和耐用度较高;2#锋利型砂轮在砂轮线速度17500r/min、工件转速280r/min、轴向进给速率1000mm/min和径向进刀量0.015mm的工艺条件下,试验砂轮的加工效率较高,加工工件的尺寸精度高且工件表面质量好。     

成形工艺对陶瓷结合剂金刚石砂轮磨削性能的影响

通过单向冷压、双向冷压和冷等静压3种不同成形工艺制备规格为D45W5陶瓷结合剂金刚石砂轮,分别加工洛氏硬度为71和85的硬质合金及45#钢,检测砂轮的磨削比和磨削效率、被加工工件的表面粗糙度和显微结构,研究不同成形工艺对砂轮磨削性能的影响。结果表明:经等静压处理的砂轮磨削不同工件时,其砂轮在磨削比和磨削效率高,工件表面粗糙度低,且工件表面划痕分布均匀且浅。     

氧化锆陶瓷沟道磨削表面质量研究

在氧化锆陶瓷沟道磨削中,为提高表面质量,并提高磨削效率、降低成本,采用单因素实验切入式磨削沟道,研究工艺参数对氧化锆陶瓷沟道表面质量的影响规律及材料的去除机理,并通过扫描电子显微镜,观察磨削后的表面形貌,在单因素实验基础上进行正交实验,对工艺参数进行优化.实验结果表明,表面粗糙度值Ra、R3y 、Rz随磨削深度、砂轮线速度、工件进给速度增大而减小;优化组合参数为磨削深度20 μm、砂轮线速度40 m/s、工件进给速度7 000 mm/min.为提高磨削效率、降低成本,可以适当提高磨削深度,适当的增加磨削热量有利于降低表面粗糙度;采用切入式方法磨削沟道,磨削内圈沟道时,尽量选用半径较大的金刚石砂轮;存在适当大小的峰谷高度差,波谷可以起到储油作用,有助于轴承润滑,减少轴承磨损.     

电镀超硬磨料砂轮修整技术现状与展望

电镀超硬磨料砂轮以其优异的磨削性能在难加工材料的精密成形磨削加工领域被广泛应用,但由于其磨削技术仍处于发展初期,还存在许多未解决的难题,而电镀超硬磨料砂轮的修整就是难题之一,该问题严重制约了此类砂轮的进一步拓展应用。文章针对电镀超硬磨料砂轮的修整技术,综述了电镀超硬砂轮在工程应用中主要的修整技术和先进的修整技术研究现状,通过分析各种修整技术的原理、特点及存在的问题,总结出对于不同复杂程度和精度要求的电镀超硬砂轮所对应的修整方法,并对电镀超硬砂轮修整技术的进一步发展趋势做出展望。     

蠕动进给碳化钨砂轮高速磨削实验研究

描述了在蠕动进给碳化钨砂轮磨削时的磨削应力和磨损的实验研究,这项实验是在热固性树脂结合剂砂轮的工作台移动速度从0.02m/min到0.4m/min和磨削速度从32m/s到58m/s的条件下进行的,当磨削速度提高到58m/s且工作台移动速度小于0.1m/min时,磨削力达到稳定状态,并且不会随着磨除率的增加而增大,砂轮磨损降低,这时可得到良好的磨削效果.     

钎焊金刚石砂轮磨削YG8硬质合金的试验研究

采用细粒度钎焊金刚石砂轮(粒度100/120)对YG8硬质合金进行磨削性能评价。结果表明:法向磨削力和切向磨削力均随着砂轮线速度的增大而减小、随着工件进给速度和磨削深度的增加而增大,其中磨削深度对磨削力的影响最大;法向磨削力与切向磨削力存在线性关系,其比值约为4.17;砂轮/工件接触面符合库伦摩擦定律,滑动摩擦系数为0.24;磨削后工件表面粗糙度随着砂轮线速度的增加而下降、随着进给速度和切深的增加而增加,其垂直方向粗糙度0.6~0.9μm,平行方向粗糙度0.05~0.2μm。     

应用陶瓷cBN砂轮的微型轴承套圈内圆磨削方案

研究开发了应用陶瓷cBN砂轮的微型轴承套圈内圆磨削方案,对比分析研究了不同砂轮磨削过程中出现的电流、功率峰值数设置等问题原因并针对性进行改善。实验数据表明:与刚玉砂轮相比,采用陶瓷cBN砂轮磨削微型轴承套圈内圆,工件内径尺寸散差下降78%,工件粗糙度R_a的波动幅度下降50%。采用无序滚轮修整后砂轮的耐用度较有序滚轮修整后cBN砂轮的耐用度提高33%,砂轮的磨削效率相差30%。砂轮芯轴刚性提高后总磨削时间较优化前减少25.8%,芯轴刚性改善后砂轮的功率峰值较之前提高50%。开发出的内圆磨削方案,可提升轴承套圈内圆磨削质量的一致性,降低磨削成本。     

超硬磨料砂轮圆弧修整技术综述

超硬磨料砂轮以其优异的磨削性能获得业内普遍认可。但是,由于超硬磨料具有很高的硬度及耐磨性,使其砂轮修整极其困难。对于复杂形面砂轮修整,则更是难上加难。为此,选最简单形面-圆弧砂轮修整为研究对象,梳理了超硬磨料砂轮圆弧修整相关技术,分析了工作原理、修整特点及其应用状况。结果发现：基于金刚石的机械式修整仍是当下超硬磨料砂轮圆弧修整之主流;点轮摆动修整,适于疏松型结合剂砂轮修整;成型修整、插补修整,易损伤工具轮精度,主要用于砂轮精修整、点修整;展成法修整,主要用于精修整。普通磨料磨具,以其脆硬特性以柔克刚,主要用于密实型结合剂超硬磨料砂轮圆弧修整;往复+摆动复合修整,主要用于大圆弧修整;插补修整,用于小众砂轮圆弧修整;往复+插补复合修整,多用于小圆弧修整;电火花成型修整,适于导电性金属结合剂砂轮粗修整;激光修整,寿命超长,但修整技术尚存不足。集非接触与机械式协同之复合修整是工程界期待的超硬磨料砂轮圆弧理想修整方法,尚需深入研究。     

用磨粒为ABN800的立方氮化硼砂轮磨削Inconel718

立方氮化硼(cBN)磨削技术为林林总总的工业生产带来了许多好处,包括它在汽车制造业、航空和航天工业中的运用,它可以提高生产率,降低生产成本,减少噪音.一直以来,相关研究都表明通过磨削即可得到表面完整性极好的工件是立方氮化硼(cBN)的独特机械性能尤其是热性能发挥作用的结果.然而,尽管cBN优点众多,但它却很难在实际应用领域中占优势,既使是在对工件表面完整度要求极其迫切的领域中,以及普通磨料被广泛应用的领域中,cBN的应用都颇多阻碍.在既定应用领域中决定cBN成本效益的一个关键因素是修整间隔,使修整间隔最优化可以明显地改善超硬磨料磨削过程的经济效益,通常来说,砂轮在修整过程中的消耗要多于磨削过程本身.超硬磨料砂轮的修整间隔是由其形状或成型磨砂轮的外径决定的.修整超硬磨料砂轮必须离线操作(可认为是生产停工),陶瓷结合剂cBN砂轮的修整方案对保持砂轮性能来说十分重要,文章将集中探讨采用不同修整参数会对Inconel718的磨削过程产生何种影响.     

超硬砂轮精密修整中异常点修正方法研究

磨粒加工作为现代“高精、高效”零部件加工手段,相比其它加工方法具有不可替代性。其中以“高精度、复杂型面”为代表的超硬材料电镀砂轮,作为磨粒加工重点发展工具之一,相比传统磨具,具有磨削比高、磨削力小、发热少、环境友好、加工精度一致性好等优势,在现代高精密磨削中地位优势突发明显。而电镀砂轮因其本身采用人类已知的最硬材料金刚石、cBN磨料制成,其型面修整工具耐磨性与电镀砂轮相当,修整难度极大。其中工具砂轮本身的制造精度低、修整过程磨损严重,是造成超硬砂轮型面修整精度低的关键原因。针对电镀砂轮精密整形的技术难题,文章借鉴Pareto多目标优化问题解决思路,构建超硬砂轮复杂型面插补修整粒子矩阵模型,提出了利于工程应用的坐标单向逼近算法。通过坐标单向逼近算法推导出矩阵粒子实际位置与理想位置的坐标偏差矩阵,对修整路径的进行修正,得到最优修整路径。从而使工具砂轮制造精度低、修整过程磨损的难题得到有效补偿。最终通过电镀砂轮修整实验,验证了算法的正确性。     

The mechanism investigation of ultrasonic roller dressing vitrified bonded CBN grinding wheel

To clarify the ultrasonic roller dressing mechanism of the vitrified bonded cubic boron nitride grinding wheel (V-CBN), the collision number model between the diamond dresser and CBN grits was established based on the geometric and kinematics analysis. The influence of each dressing parameter on the collision number was analyzed and discussed. The grinding experiment was performed on the bearing raceway with the dressed V-CBN grinding wheel, results obtained discovered that there was an inverse relationship between the collision number and the surface roughness and runout of the workpiece. Additionally, compared with conventional dressing, ultrasonic dressing has the advantage in improving the surface quality because it can produce more collision numbers and raise grit retention. In words, the collision number can be used to predict the dressing effect, which provides a reference for formulating an appropriate dressing process for V-CBN to improve the workpiece surface quality and production efficiency.     

Morphological evolution and grinding performance of vitrified bonded microcrystal alumina abrasive wheel dressed with a single-grit diamond

Dressing experiments under different conditions were carried out on a vitrified bonded microcrystal alumina abrasive wheel with a single-grit diamond dresser. The grinding performance of the as-dressed abrasive wheels was investigated. The dressing force, grinding force and the surface morphology of abrasive wheel and machined workpiece were studied to shed light on the relationship among the dressing processing vectors, morphology of abrasive wheel and the grinding performance. The results obtained show that the dressing forces increase with the increasing volume of the abrasive wheel material removed per unit time. The sensitive analysis reveals that the dressing feed speed take a greater effect than the single dressing depth on the dressing force. The self-sharpness of vitrified bonded microcrystal alumina abrasive wheel brings into some functions under certain dressing conditions, but a deep dressing depth would lead to an excessive abrasive self-sharpness, i.e. abrasive grits fall off and embed into the workpiece surface.     

陶瓷轴承外圈内圆磨削力与表面质量研究

为了探究陶瓷轴承外圈内圆(简称外圆)磨削力以及磨削力对表面质量的影响机制,通过磨削实验首先获得了不同磨削参数对外圆磨削力的影响规律,其次得出了旋转磨削力与表面粗糙度和表面去除方式的关系。结果表明,随着砂轮速度减小,进给量和工件转速增加,陶瓷外圆磨削法向与切向磨削力均增加,且法向磨削力是切向磨削力的3倍左右;当磨削力增大,磨削表面由塑性去除向脆性去除转变,表面粗糙度值增大,表面质量变差。在陶瓷轴承外圆磨削时可适当选用较高的砂轮速度、较小的进给量和工件转速以保证表面加工质量和加工效率。     

Grinding performance improvement of silicon nitride ceramics by utilizing nanofluids

Silicon nitride ceramics are widely used as advanced structural components because of their excellent thermal and mechanical properties at ambient and elevated temperatures. In manufacturing industries, grinding is an efficient and productive technique for finishing ceramic workpieces. However, high wheel-workpiece friction and the extreme hardness associated with silicon nitride cause large heat generation during grinding. The heat produced during grinding impairs the workpiece quality by inducing surface and sub-surface damages, tensile residual stresses etc. The damages can critically limit the applications of ground ceramic components. Extensive experimental studies have been carried out to find the effect of dry and nano MQL (Graphite, WS₂ and MoS₂) grinding conditions on silicon nitride using resin bonded diamond wheel at different parametric (wheel speed, depth of cut and table speed) combinations. Results indicate that the use of nanofluids considerably improve the process performance in terms of grinding forces, surface finish and sub-surface damage. The ground surface is characterized by optical microscopy, SEM/EDX and XRD.     

Theoretical model of warping deformation during self-rotating grinding of YAG wafers

YAG wafers are the most host laser crystals used for high-power lasers, which are usually machined by grinding to meet the required accuracy for laser components. Warping deformation induced by the residual stress is one of the main damages for YAG wafers after the grinding process, which will seriously decrease the service accuracy and life of the lasers. Developing theoretical model of warping deformation is of great significance to achieving the ultra-precision machining of YAG wafers. The cutting depth of single abrasive and grinding force in self-rotating grinding were investigated by considering the kinematic trajectory of abrasives, brittle-to-ductile transition, elastic mechanics, elastic deformation of the grinding wheel and strain rate effect. A theoretical model of warping deformation in self-rotating grinding of YAG wafers was developed based on the cutting depth and grinding force. The influence of subsurface damage and residual stress on warping deformation was analyzed based on the theoretical model and finite element simulation. Self-rotating grinding tests of YAG wafers were performed, and the results showed that the warping deformation decreased as the wheel rotational speed increased, and increased as the abrasive size, workpiece rotational speed and feed speed increased. The experimental results agreed well with the simulated results of the theoretical model, indicating that the theoretical model can accurately predict the warping deformation induced by self-rotating grinding process. This work will not only enhance the understanding of the essence of the wafer warping induced by ultra-precision machining, but also provide a guide for optimizing the processing parameters in self-rotating grinding of YAG wafers.     

Research on laser preparation and grinding performance of hydrophilic structured grinding wheels

In order to solve the problems of workpiece damage and grinding wheel clogging when grinding difficult-to-cut materials such as alumina ceramics, organisms with regular hexagonal structures distributed on the body surface and with strong hydrophilicity and high anti-wear functions were used as biomimetic objects for the first time, and the preparation process optimization, structure size design and grinding performance evaluation of hydrophilic structured bronze-bonded diamond grinding wheels were explored in this paper. The influence of the preparation process parameters on the micro-topography and the dimensional accuracy of the structure on the surface of the grinding wheel was revealed, and a new laser structuring process based on the coordinated control of focus position and scanning times was proposed, which could efficiently prepare regular hexagonal structures with a small wall inclination angle and a depth of several millimeters on the surface of the grinding wheel. It was the first to clarify the influence of sub-millimeter-scale structure size on the contact angle of grinding fluid droplet on the surface of the grinding wheel and the surface hydrophilicity of the grinding wheel. Compared with that of the non-structured grinding wheel, the hydrophilicity of the structured grinding wheel was significantly improved, and its surface hydrophilicity increased with the increase of the structure spacing and depth, but had little correlation with the structure side length. The grinding performance of hydrophilic structured grinding wheels and non-structured grinding wheels was evaluated under extreme working conditions. Under the condition of grinding depth of 50 μm, 100 μm and 200 μm, compared with that of the non-structured grinding wheel, the peak grinding temperature of the structured grinding wheel was reduced by 18.0%, 30.4% and 15.2%, respectively, and the surface damage depth of the alumina ceramic after grinding by the structured grinding wheel was reduced by 53.7%, 46.8% and 24.3%, respectively. The hydrophilic structured grinding wheel can enhance the storage and transportation capacity of grinding fluid/chips, effectively relieve the clogging and dullness of the grinding wheel, and significantly reduce the high temperature and damage of grinding. In the next step, we will try to apply this type of grinding wheel to form grinding, in order to provide a reliable solution for suppressing form grinding damage of difficult-to-cut materials.     

在MQ1350A磨床上磨削高精度抛光辊

通过选用合理的砂轮、磨削工艺参数、磨削液等并进行适当的修整砂轮、调整与平衡磨床,即可在MQ1350A普通外圆磨床上磨削修复进口1450冷轧机抛光辊。经分析磨削结果可知,在MQ1350A普通外圆磨床上磨削高精度要求的进口1450冷轧机抛光辊是完全可行的。     

Modified gel casting technique to fabricate honeycomb structured vitrified-bonded ultrafine diamond grinding wheels

To avoid agglomeration of ultrafine diamond particles and to improve machining precision of silicon (Si) wafers, a combination of gel casting and pore-forming agent is introduced to fabricate vitrified-bonded ultrafine diamond grinding wheel with ultrahigh porosity (~75%), honeycomb structure, and homogeneous microstructure. Moreover, the as-prepared grinding wheel possesses uniformly distributed closed pores, which are highly desirable for chip removal, heat dissipation and extended service life. In addition, influences of sintering schedules on microstructure, porosity and bending strength of the as-prepared grinding wheel are systematically investigated. Because of the honeycomb structure, the as-fabricated grinding wheel renders superior self-sharpness, which is required for continuous grinding of Si wafers without dressing, and this subsequently enhances the working efficiency. Results reveal that the surface roughness and damaged layer of the ground Si wafers are approximately 5.0 nm and 0.21 μm, respectively. The current study provides a novel pathway for efficiently processing high-quality silicon wafers.     

辊磨磨盘转速对粉磨能力的影响

基于变频调速直驱电机,研究了不同辊磨磨盘转速对辊磨产量的影响,试验结果显示,磨盘转速调节对水泥厂产量提升和降低能耗有较大助力。     

Grinding performance improvement of laser micro-structured silicon nitride ceramics by laser macro-structured diamond wheels

Silicon nitride ceramics are widely used in various industrial fields because of their excellent characteristics: high hardness, high elastic modulus, abrasion resistance, and high heat resistance. Diamond wheel grinding is the predominant and most productive method to machine silicon nitride ceramics. However, a lot of heat is generated due to high friction between a diamond grinding wheel and extremely rigid silicon nitride during grinding. This causes surface/subsurface damage, wheel wear, etc., which impairs the surface quality of silicon nitride. This impairment can restrict the use of silicon nitride ceramic components. To improve the surface quality and service life of grinding wheels, a laser macro-micro combination structured grinding (LMMCSG) method was presented. The results indicated that the grinding force ratio and surface roughness when using LMMCSG were respectively 31% and 40% lower than the grinding force ratio and surface roughness when using conventional grinding. Moreover, the LMMCSG method effectively reduced the wheel wear and workpiece subsurface damage.