GH33A高温合金的磨削温度与残余应力

以ＧＨ３３Ａ为例，分析了磨削时传入工件表层热量的百分比；计算了不同深度处的磨削温度，并试验验证了磨削温度场的计算结果。在考虑磨削温度对材料性能影响的条件下，分析计算了磨削残余应力。     

颗粒增强钛基复材缓进深切磨削加工研究

颗粒增强钛基复合材料(PTMCs)属于典型的难加工材料,在航空航天领域具有广阔应用前景.本文开展了PTMCs材料的缓进深切磨削研究,揭示了磨削用量和磨削方式(顺磨与逆磨)对磨削力与磨削温度的影响规律,同时利用有限元法分析了磨削温度场特征和材料去除机理.研究发现,缓进深切磨削PTMCs时,磨削力随工件进给速度和切深增加而增加,顺磨时的磨削力比逆磨大10％～20％,而顺磨的磨削温度要比逆磨约低10％.由于逆磨和顺磨工件的温度分布不同,当切深大于0.6mm、工件进给速度大于400mm/min时,顺磨比逆磨更易发生烧伤.在此基础上,提出了顺磨与逆磨条件下磨削温度场仿真计算的不同热源模型与边界条件,分别获得了两种磨削方式的温度分布特征,有限元仿真结果与试验结果相符.颗粒增强钛基复材磨削表面典型加工缺陷是表面涂覆和硬脆增强相破碎和拔出导致的孔洞,单颗磨粒切厚对硬脆增强相的去除行为有显著的影响.     

断续缓磨射流冲击强化磨削弧区换热的实验研究

通过深切缓磨时磨削烧伤机理的分析,提出高压射流冲击强化磨削弧区换热新构想,并通过断续缓磨射流侧向冲击弧区的磨削实验显示其换热效果．     

平面磨削温度场计算中的几个问题

平面磨削温度的实测值常低于目前的计算值,本文对原计算公式提出了修正,并给出了相应的计算公式以及使用这些公式的条件。     

断续 CBN 砂轮缓进给磨削 K417 航空叶片材料的研究

 全面比较了用Al2O3和CBN磨削K417铸造高温合金时的磨削效果，指出：Al2O3不适于高效磨削K417之类的航空难加工材料，而CBN是实现该材料高效深切磨削的有效工具。通过大量实验，验证了断续CBN砂轮缓进给磨削K417时的技术优势，解决了树脂结合剂应用于断续磨削时所遇到的新问题。分析显示出该技术具有很好的应用前景和极大的推广价值。     

用切点跟踪磨削法磨削曲轴的研究与应用

阐述了用切点跟踪磨削法磨削曲轴的原理,对数控插补逼近所带来的误差进行了分析和计算。通过对传统曲轴磨削加工中存在问题的分析,重点介绍了用切点跟踪磨削法磨削曲轴的工艺,包括磨削用量的选择、砂轮的选择、曲轴的定位与夹紧、数控曲轴磨床的调整、磨不同型号曲轴的调整等。磨削试验证明,切点跟踪磨削法具有高精度、高柔性和高效率的特点,是曲轴磨削加工方法的发展方向。     

冷滚打渐开线花键滚轮磨削建模研究

根据成形磨削的特点,在分析砂轮形状及其磨损的基础上,选择圆弧形砂轮截面进行冷滚打花键的磨削。磨削时接触点沿砂轮廓形曲线移动,不仅砂轮廓形曲线磨损均匀,而且提高了砂轮的耐用度,减少了砂轮的修整次数。试验结果表明,本文的理论分析、公式推导是正确的,为滚打轮的设计制造提供了理论依据,为其工艺参数的制定和磨床的设计提供了数学指导。     

磨削力的实时采集和数据处理

磨削一般是零件加工的最后一道工序。磨削过程较为复杂，磨削力的大小不仅影响工件的表面质量，而且还影响零件的精度。在磨削机理研究及生产实际中常常需对磨削力进行测试，通过调整磨削用量，修整砂轮，实现在允许的磨削力范围内进行加工。提出了在磨床上安装测力系统，并采用单片机对磨削力信号进行实时采集处理，建立磨削力的经验公式，同时显示并打印结果。     

镍基高温合金的磨削特征

以GH4169高温合金为主要研究对象,论述了高温合金的磨削特征。由于高温合金的难磨性以及磨削时砂轮表面存在严重的粘附物,因而使磨削力和磨削温度显着增高,磨削比非常低。     

表面硬化钢磨削表层质量的研究

 表面硬化钢磨削时容易引起烧伤,本文以单位面积磨削功率北P_c″作为磨削过程特征参量,应用各种测量技术评价磨削表层状态。试验表明,不同的磨削表层质量与P_c″有很好的对应关系。     

缓磨烧伤过程的计算机仿真研究

在关于缓磨时的磨削热 ,接触弧区换热过程以及工件表层非稳态温度场的深入研究的基础上 ,构造了一可用于计算缓磨烧伤前后工件表层温度场畸变历程的数学模型 ,并据此完成了关于缓磨烧伤过程的计算机仿真研究 ,仿真结果与实际吻合良好 ,它率先阐明了缓磨烧伤的热机理并且证明了缓磨烧伤是一具有明显前兆特征的典型渐变过程     

Suppression of Surface Burn in Grinding of Titanium Alloy TC4 Using a Self-inhaling Internal Cooling Wheel

Based on analysis of surface average temperature and burn degree, this article obtains the threshold temperature of surface burn in grinding titanium alloy with cup wheels. Meanwhile, the impact of the burn degree on the metallographic structure of workpiece surface and metallurgical phase transformations is investigated. In order to reduce the grinding temperature and improve the grinding efficiency, a self-inhaling structure cup segmented wheel is developed to generate internal cooling effect. The internal cooling technology is compared with traditional cooling conditions in the grinding experiments on TC4 (Ti-6Al-4V). The results indicate that the self-inhaling internal cooling wheel can reduce the grinding surface temperature by 30% or more, and the grinding efficiency doubles. Utilizing water-based semi-synthetic coolant, the segmented wheel with the self-inhaling structure can further reduce the grinding temperature by about 50%.     

TC4钛合金高速外圆磨削表面完整性实验

为充分发挥钛合金的优良性能,以TC4为研究对象进行高速外圆磨削实验,分析外圆磨削工艺参数对工件表面完整性的影响规律。结果表明:工件亚表面未出现变质层;随着砂轮线速度提高,表面质量提高;随着工件转速提高,表面划痕明显;随着磨削深度增加,出现表面烧伤现象,并且磨削深度对表面完整性的影响程度最大;磨削力与磨削温度对表面硬度的影响是正相关的,且磨削力对表面硬度的影响程度较大。因此可以通过选择合理的工艺参数来保证较大的材料去除率与较好的工件表面质量,为TC4钛合金高速外圆磨削提供指导。     

Development of a new high-shear and low-pressure grinding wheel and its grinding characteristics for Inconel718 alloy

Nickel-based alloy has been widely used due to its outstanding mechanical properties. However, Nickel-based alloy is a typical difficult-to-machine material, which is a great constrain for its application in the manufacturing field. To improve the surface quality of the ground workpiece, a new high-shear and low-pressure grinding wheel, with high ratio of tangential grinding force to normal grinding force, was fabricated for the grinding of selective laser melting (SLM) manufactured Inconel718 alloy. The principle of high-shear and low-pressure grinding process was introduced in detail, which was quite different from the conventional grinding process. The fabrication process of the new grinding wheel was illustrated. A serial of experiments with different processing parameters were carried out to investigate the grinding performance of the developed grinding wheel via analyzing surface roughness and surface morphology of the ground workpiece. The optimal processing parameters of high-shear and low-pressure grinding were obtained. The surface roughness of ground workpiece was reduced to 0.232 μm from the initial value of 0.490 μm under the optimal grinding conditions. It was found that the initial scratches on the ground workpiece were almost completely removed after the observations with the metalloscopy and the field-emission scanning electron microscopy (FE-SEM). The capability of the newly developed high-shear and low-pressure grinding wheel was validated.     

Grindability and Surface Integrity of Cast Nickel-based Superalloy in Creep Feed Grinding with Brazed CBN Abrasive Wheels

The technique of creep feed grinding is most suitable for geometrical shaping, and therefore has been expected to improve effectively material removal rate and surface quality of components with complex profile. This article studies experimentally the effects of process parameters (i.e. wheel speed, workpiece speed and depth of cut) on the grindability and surface integrity of cast nickel-based superalloys, i.e. K424, during creep feed grinding with brazed cubic boron nitride (CBN) abrasive wheels. Some important factors, such as grinding force and temperature, specific grinding energy, size stability, surface topography, microhardness and microstructure alteration of the sub-surface, residual stresses, are investigated in detail. The results show that during creep feed grinding with brazed CBN wheels, low grinding temperature at about 100 °C is obtained though the specific grinding energy of nickel-based superalloys is high up to 200-300 J/mm³. A combination of wheel speed 22.5 m/s, workpiece speed 0.1 m/min, depth of cut 0.2 mm accomplishes the straight grooves with the expected dimensional accuracy. Moreover, the compressive residual stresses are formed in the burn-free and crack-free ground surface.     

Developing a novel radial ultrasonic vibration-assisted grinding device and evaluating its performance in machining PTMCs

Particle-reinforcing titanium matrix composites(PTMCs) exhibit the sharp raising applications in modern industries owing to its extraordinary physical and mechanical properties. However, the poor grindability and unstable grinding processes due to the existence of TiC particles and TiB short fibres inside PTMCs, leading to the sudden grinding burn and low material removal rate.In this work, a novel radial ultrasonic vibration-assisted grinding(RUVAG) device with a special cross structure was dev...     

K417航空叶片材料缓进深磨烧伤特征及烧伤程度判别

 利用扫描电镜、电子探针、x射线光电子谱仪等测试分析手段,按照传统的烧伤分档标准对K417铸造镍基高温合金缓进磨削时烧伤表面的形成机理及烧伤表面层物理性态所发生的种种变化进行了系统的研究。文中针对高温合金本身的特点,结合性态测试与疲劳试验结果指出:仅有紫色档才可能对零件的使用寿命构成实质性损伤。     

氧化锆陶瓷拉伸试件的精密磨削

对氧化锆陶瓷拉伸试件的精密磨削进行了研究。提出了一种新型的成形修整装置,用于平型带弧金刚石砂轮的修整;并对表面粗糙度、弧型部分的廓形、试件的对称性等问题进行了探讨。