高速立方氮化硼砂轮与绿色制造

以磨削加工汽车发动机凸轮轴、曲轴为例,对陶瓷CBN砂轮与普通刚玉砂轮进行了加工效果对比。结果表明:高速陶瓷CBN砂轮的耐用度是普通陶瓷刚玉砂轮的100倍,寿命是普通砂轮的的44.4倍,而原材料消耗仅为其1/56;加工相同的工件数量,使用刚玉砂轮进行加工,磨料消耗是高速CBN砂轮的400余倍;采用高速陶瓷CBN砂轮代替刚玉砂轮可提高生产效率30%以上,综合生产成本比刚玉砂轮磨削降低60%。高速CBN砂轮具有高效率、高精度、低磨削成本,低环境污染的技术优势,其代表了当今世界磨具产品发展的一个主要方向,是实现绿色加工目标的有效手段。     

CBN磨料特性对树脂砂轮磨削性能的影响

对6种不同CBN磨料的静压破碎负荷、冲击韧性（TI）和热冲击韧性（TTI）的数据进行分析研究,并分别制作成树脂结合剂砂轮。针对不同材料工件进行磨削,研究不同CBN磨料制作的砂轮磨削铸铁、高速钢、不锈钢和氮化不锈钢等材料的磨削比。实验结果表明:同样结合剂和工艺条件下,不同CBN磨料制作砂轮的磨削比相差较大;树脂CBN砂轮对铸铁和高速钢材料的磨削比相对较高,但对不锈钢和氮化不锈钢材料的磨削比低;CBN-B1500和CBN850磨料对几种工件材料的磨削性能相对较好。树脂CBN砂轮中磨料靠结合剂机械嵌合力把持,因此具有粗糙表面和适中静压破碎负荷的CBN磨料是较优选择。      

磨喷油嘴陶瓷结合剂CBN砂轮的研制及应用

本文对磨喷油嘴陶瓷结合剂CBN砂轮的制备及应用进行了研究,制定了适宜的陶瓷结合剂CBN砂轮的制备条件。所研制的陶瓷结合剂CBN砂轮磨削性能好,生产效率高,使用寿命长,加工工件质量高,能很好地满足喷油嘴的加工要求,且性能价格比优于普通砂轮和进口陶瓷结合剂CBN砂轮。     

Experimental characterization of micro-grinding process using compressed chilly air

The objective of this research is to characterize the micro-grinding process under the condition of compressed chilly air in the meso-scale grinding machine tool system. The meso-scale grinding machine tool having the size of 210×190×220 mm is developed in a horizontal configuration. To investigate the effect of compressed chilly air on the micro-grinding performances, grinding force, tool wear patterns and surface roughness are measured and analyzed with varying depths-of-cut feed speeds and temperatures of the compressed air. A series of micro-grinding experiments are conducted by considering electroplated CBN grinding tool and stainless steel workpiece and vitrified CBN grinding tool and tool steel workpiece. The experimental results show the effectiveness of compressed chilly air and its ability to improve tool life with decreased grinding forces in the micro-grinding process.     

CBN磁性磨料磁力研磨TC4钛合金工艺参数优化

为提高磁力研磨TC4钛合金的研磨效果,采用了一种新型CBN磁性磨料,通过正交试验法对磁力研磨TC4钛合金试验中各工艺参数进行优化,并通过试验评价新型CBN磁性磨料的结合强度和研磨能力。结果表明:优化工艺参数为:进给速度1mm/min、主轴转速1500r/min、加工间隙1mm和磨料填充量2.5g。在采用CBN磁性磨料和最优工艺参数组合下,钛合金工件经过30min研磨表面粗糙度从0.330μm下降到0.098μm,表面质量明显提高。研磨60min后磁性磨料未出现磨料脱落和破碎现象,磨料结合十分牢固。     

高速陶瓷CBN砂轮贴片的实验研究

本文从影响高速CBN砂轮陶瓷贴片性能的因素入手,凭借扫描电镜、差热分析仪等先进精密仪器对磨料进行了常温性能、差热分析、焙烧处理（870℃）分析;同时对陶瓷结合剂配成原理、比例和性能进行了试验探讨;利用ANSYS软件对陶瓷砂轮贴片的尺寸大小进行了优化分析;最后,利用超高速点磨削试验台对焙烧好的砂轮贴片进行了磨削性能实验。实验表明：研发的低温高强陶瓷结合剂,该配方结合剂的耐火度890℃,抗折强度达到了60.13 MPa;烧制的陶瓷贴片在小进给、小切深、超高速磨削下,表面粗糙度Ra值为0.002 mm左右。     

Precision grinding using CBN wheels

The paper systematically reviews experimental research on the performance of cubic boron nitride (CBN) grinding wheels and discusses advantages and difficulties experienced in the application of CBN wheels particularly for internal grinding with fine-grain wheels.The hardness of CBN grains potentially increases re-dress life and improves dimensional stability. The problem is that increased re-dress life increases the importance of avoiding wheel loading, particularly for small-grain wheels. This paper highlights the importance of touch dressing for improved dimensional stability and other operational techniques to maintain an open surface topography of the wheel. The paper also demonstrates the benefit of an open-structured small-grain CBN wheel for precision grinding. Effects on grinding temperature are also illustrated.     

Thermal Analysis of Grinding

Thermal damage is one of the main limitations of the grinding process, so it is important to understand the factors which affect grinding temperatures. This paper presents an overview of analytical methods to calculate grinding temperatures and their effect on thermal damage. The general analytical approach consists of modeling the grinding zone as a heat source which moves along the workpiece surface. A critical factor for calculating grinding temperatures is the energy partition, which is the fraction of the grinding energy transported as heat to the workpiece at the grinding zone. For shallow cut grinding with conventional abrasive wheels, the energy partition is typically 60%-85%. However for creep-feed grinding with slow workspeeds and large depths of cut, the energy partition is only about 5%. Such low energy partitions are attributed to cooling by the fluid at the grinding zone. Heat conduction to the grains can also reduce the energy partition especially with CBN abrasives which have high thermal conductivity. For High Efficiency Deep Grinding (HEDG) using CBN wheels with large depths of cut and fast workspeeds, preheated material ahead of the grinding zone is removed together with the chips, thereby lowering the temperature on the finished surface. Analytical models have been developed which take all of these effects into account. Much more research is needed to better understand and quantify how grinding temperatures affect the surface integrity of the finished workpiece.     

Improving minimum quantity lubrication in CBN grinding using compressed air wheel cleaning

The application of minimum quantity lubrication (MQL) in grinding has emerged as an alternative for reducing the abundant flow of cutting fluids, thus achieving cleaner production. Although considered an innovative technique in grinding operations, its widespread application is hindered due primarily to the high heat generation and wheel pore clogging caused by machined chips, harming the final product quality and increasing tool wear on the machine. This study sought to improve MQL use in grinding. In addition to the conventional MQL injected at the wheel/workpiece interface, a compressed air jet was used to clean the mixture of MQL oil and machined chips from clogged wheel pores. Experiments were conducted using external cylindrical plunge grinding on AISI 4340 quenched and tempered steel, and a vitrified cubic boron nitrite (CBN) wheel. The cooling-lubrication methods employed were the conventional flood coolant application, MQL (without cleaning), and MQL with a cleaning jet directed at the wheel surface at different angles of incidence. The main goal of these experiments was to verify the viability of replacing the traditional abundant flow of cutting fluid with MQL and wheel cleaning. The analyses were conducted by measuring the following output variables of the process: workpiece surface roughness and roundness errors, diametrical wheel wear, acoustic emission generated by the process, and metallographic images of the ground surface and subsurface. Results show the positive effects of implementing the cleaning jet technique as a technological improvement of minimum quantity lubrication in grinding in order to reduce the usage of cutting fluids. The MQL technique with cleaning compressed air jet, for a specific angle of incidence (30°), proved to be extremely efficient in the improvement of the surface quality and accurate workpiece shape; it also reduced wheel wear when compared to the other cooling-lubrication methods that were tested (without a cleaning jet).     

单颗CBN磨粒高速磨削过程的仿真研究

为研究单颗CBN磨粒高速/超高速磨削的微观机理,以随机形状CBN磨粒为模型,采用Lagrange/Euler流固耦合方法,仿真分析不同工艺参数下的CBN磨粒磨削SHK-9高速钢的过程。结果表明:CBN磨粒（124~150μm）在切削深度a_p 20 μm、30 μm,切削速度120m/s时,切向磨削力达到最大,但在a_p 40 μm切削深度下反而最小。随着CBN磨料粒度尺寸变小,磨削力下降明显,磨粒可以在工件表面形成更为窄密的耕犁沟痕,配合适当的磨削深度有助于提高表面磨削质量。      

陶瓷CBN砂轮修整参数的量化分析研究

采用正交试验方法量化分析了陶瓷CBN砂轮的修整参数对工件表面质量的影响。研究结果表明:进给速度对工件表面粗糙度和支承长度率均有明显的影响;修整量对表面粗糙度影响较小,但对支承长度率却有较为明显的影响,且修整时往复次数越少,砂轮越锋利;修整速差对表面质量影响较小。因此,可以通过加大进给速度、降低单次深度和增大往复次数的方法,来达到提高首件表面粗糙度、增加修整间隔、提高砂轮使用寿命的目的。      

多孔CBN/Cu-Sn-Zn堆积磨料在钢轨打磨砂轮中的应用

为提高钢轨打磨砂轮的磨削效率和使用寿命,制备一种表面多孔但内部紧实的CBN/Cu-Sn-Zn堆积磨料。讨论Cu-Sn-Zn结合剂的性能、孔隙结构对CBN堆积磨料的影响以及堆积磨料对砂轮结构强度的影响,并通过钢轨被动打磨试验,对堆积磨料添加前后砂轮的磨削效果进行评价。试验结果表明:最佳的多孔CBN堆积磨料试样弯曲强度为78.5?MPa,抗冲击强度为5.5?kJ/m2,表面孔隙率在30%～40%。磨料的复合使用可以有效地结合CBN高硬度与锆刚玉良好的冲击韧性的特点,添加体积分数为20%的堆积磨料提高钢轨打磨砂轮的打磨效率及打磨质量。      

低温陶瓷结合剂CBN平面磨砂轮的制备工艺研究

本文系统地研究了用低温陶瓷结合剂制作CBN平面磨砂轮的工艺过程,确定了合适的工艺参数。结果表明:选用烧制温度范围较宽(660～800℃)的低温陶瓷结合剂,可以通过调节烧结温度调整砂轮的硬度和强度,缓慢的升温和降温速度是抑制砂轮产生裂纹的有效方法;加入造孔剂既能得到满足客户需要的孔隙率,又能保证其抗折强度不低于30MPa。砂轮强度随气孔率增加而快速降低,当气孔率为18.02%时,其抗折强度为67.33MPa;当气孔率增加到37.60%时,其抗折强度降为33.09MPa;当气孔率进一步增加到47.85%时,其抗折强度下降到20.44MPa。通过合理选用工艺参数,所制备的陶瓷结合剂CBN平面磨砂轮,具有磨削效果好,生产效率高,寿命长及性价比高的综合特性。     

钎焊CBN砂轮与陶瓷CBN砂轮磨削粉末冶金高温合金的加工性能对比研究

采用钎焊CBN砂轮和陶瓷CBN砂轮进行FGH96粉末冶金高温合金磨削对比试验,从磨削力与温度、表面粗糙度以及砂轮磨损等方面对CBN砂轮磨削性能进行评价.结果表明:钎焊CBN砂轮磨削力接近或低于陶瓷CBN砂轮的;在较低进给速度下(≤360 mm/min),钎焊CBN砂轮磨削温度与陶瓷CBN砂轮的相近,在较高进给速度下(≥...     

Turning of interrupted and continuous hardened steel surfaces using ceramic and CBN cutting tools

In the machining of hardened steel surfaces, turning instead of grinding has been employed increasingly due to several advantages it offers, such as flexibility and the possibility of dry cutting. The main tool materials used for this purpose are CBN and ceramic due to their high hardness and, in the case of some grades of these materials, high chemical stability with iron. However, when interrupted surfaces are turned, the tool requires not only these properties but also sufficient toughness to resist impacts against workpiece interruptions. Therefore, the main goal of this work is to compare CBN and ceramic tools in continuous and interrupted cutting. To this end, several turning experiments were carried out on continuous surfaces (in this case, CBN with an added ceramic phase and a mixed ceramic were compared, due to their high chemical stability and hardness) and on interrupted surfaces (here, a high CBN content and a SiC-reinforced ceramic were compared due to their good ability to withstand impacts), applying different cutting speeds. The main conclusions of this work were that in both continuous and interrupted cutting, the CBN tools exhibited a much better performance with respect to both tool life and workpiece surface roughness than the ceramic tools.     

金刚石树脂磨具的改进

以金刚石、立方氮化硼为磨料制造的树脂磨具、青铜磨具、陶瓷磨具、电镀磨具以及新兴的柔性磨具、单层钎焊磨具等超硬磨料的磨具，具有磨削力小、磨削温度低、磨削比高和加工精度高、效率高等特点；磨具的钢基体、铝合金、胶木以及新兴的铝／酚醛等不同材质的基体对磨具的寿命、加工效率和加工质量有着不同的影响规律；磨料、结合剂、辅助填料的弃旧更新以及配方的改进，有效地改善磨具性能，促进磨具更新换代；表面镀覆，磨料强度得以提高，同时减缓了对树脂结合剂的热冲击，提高了结合力，从而显著延长了磨具寿命；磨具的精加工和动平衡检查是保证高档精密磨具质量的重要措施。     

立方氮化硼砂轮的研究与发展

介绍了国内外立方氮化硼（CBN）砂轮的性能和金属结合剂（含电镀和钎焊结合剂）、树脂结合剂和陶瓷结合剂CBN砂轮的特点,论述了CBN砂轮中磨料的处理及气孔组织的调控技术。阐述了目前国内在CBN砂轮制造水平方面与国外存在的差距,提出CBN砂轮的未来制造应向着超高速、绿色制造等方向发展。      

GCr15钢平面磨削力仿真分析与实验研究

目的 对不同磨削工艺参数下的平面磨削力进行预测,对磨削机理进行研究,进而控制磨削加工质量。方法 考虑CBN砂轮表面磨粒形状的多样性、姿态的多样性和空间分布的随机性,建立CBN砂轮模型,对GCr15材料模型进行有限元砂轮磨削仿真。同时使用CBN砂轮,采用不同的工件进给速度对GCr15进行单因素平面磨削实验,使用三坐标测力仪测量不同磨削参数下的磨削力。结果 建立的仿真砂轮模型的表面形貌与真实砂轮接近,仿真砂轮上的磨粒出刃高度均服从正态分布,与实际砂轮一致。对比随机多面体磨粒模型和真实CBN磨粒照片,两者形貌相似。磨削力实验和仿真结果表明,工件进给速度由3 m/min增大到18 m/min时,磨削力逐渐增大,仿真所得法向磨削力最大误差远小于切向磨削力。结论 实验结果与仿真结果具有一致性,证明了砂轮磨削有限元仿真模型可用于磨削力预测。因为仿真中无法考虑实际砂轮尺寸和砂轮表面结合剂对磨削的影响,结果具有一定误差,仿真的准确性有待进一步提高。研究结果为使用有限元方法研究磨削机理和控制磨削加工质量提供了思路。     

干磨新工艺的试验研究

磨削加工时需要非常高的能量输入,导致磨削区温度升高,因此干磨变得非常困难。介绍一种新的方法来减少热能,即在特殊条件下使用金刚石修整器来修整CBN砂轮,使砂轮表面磨粒面积减少。实验结果表明:与同样的材料磨除率下的普通砂轮磨削过程比较,该砂轮的磨削力大幅下降,没有磨削烧伤和工件表面损伤发生。     

A study on the machining characteristics in the external plunge grinding using the current signal of the spindle motor

This paper describes the machining characteristics of external plunge grinding. The study investigates the process using the current signals of a spindle motor through a hall sensor. Grinding experiments were conducted under various grinding conditions such as wheel speeds, workpiece speeds and infeed rates with a conventional vitrified bonded wheel. Analyzing the current signal of the spindle motor, a relationship between current signals and the metal removal rate in terms of the infeed rate is induced. It was also shown that a hall sensor has similar capabilities in evaluation of grinding behavior compared to the AE signals, which are useful for monitoring the grinding process.