Identification of grinding wheel wear using random process analysis

Profiles of grinding wheel surfaces have been analysed in terms of a random signal using virtually on-line instrumentation. By this method the contribution of the three acknowledged modes of grinding wheel wear, attritious, grit fracture, and bond-post fracture (or grit dislocation), to overall wheel wear can be readily identified.Results of tests under varying conditions of controlled force plunge cylindrical grinding are reported in detail.     

A precision grinding method for screw rotors using CBN grinding wheel

Aiming at the high precision machining of screw rotors, a new grinding method for screw rotors using cubic boron nitride (CBN) grinding wheel is presented in this paper. Small electroplated CBN grinding wheel is firstly used to grind screw rotors. The mathematical model for the axial profiles of CBN grinding wheel is developed based on gear engagement theory. Taking the backlash of screw rotors and the coating thickness of CBN layer into consideration, the modification of the base body of the wheel shape is introduced into the design of the CBN grinding wheel. Wire cut electrical discharge machining low speed (WEDM-LS) was used to machine the base body of the CBN grinding wheel. The formed turning tools of the base body of CBN grinding wheel using WEDM-LS and the wheel shapes of CBN grinding wheel using the formed turning tool were performed. The CBN grinding wheels for the screw rotors were made to verify the validity and effectiveness of the presented method. The electroplated CBN grinding wheels were used to machine the screw rotors, and the machining experiments were performed. The data obtained in the experiments reach the fifth class of Chinese Standard GB10095-88.     

成形砂轮磨齿工艺中磨削烧伤缺陷的研究与防止对策

根据成形砂轮磨齿工艺的特点,说明磨削烧伤产生的原因,经过分析研究与实践,给出烧伤缺陷的防止对策.     

实现双沟轴承双沟道一次磨削的新型砂轮修整定位机构

介绍一种采用电磁铁驱动的砂轮修整定位机构,用于单沟道轴承磨床改造,实现轴承套圈双沟道一次磨削和自动磨削。阐述了该机构的工作原理与结构特点。     

Study on precision grinding of screw rotors using CBN wheel

With increasing demands for high-speed and high-precision machining technology, CBN shape grinding is an effective means in the field of precision machining for screw rotors. Aiming at the high precision machining of screw rotors, a mathematical model for the axial profiles of the CBN wheel for machining screw rotors is developed based on theory of gear engagement. Small electroplated CBN wheel is firstly used to grinding screw rotors. Taking the backlash of screw rotors and the coating thickness of CBN layer into consideration, the modification of the base body of the wheel shape is introduced into the design of CBN wheel. For reducing the tooth profile errors of screw rotors induced by mounting errors and wears of CBN wheel, a mathematical model of the error analyses is established and the influence curves of the profile errors affected by mounting errors and radius error of grinding wheel are proposed. The electroplated CBN wheels for the screw rotors are made to verify the validity and effectiveness of the presented method and the machining experiments were performed. Results of this study reveals that the method proposed in this paper can be used as the precision grinding of screw rotors.     

Experimental study on ultrasonic-assisted grinding of micro-structured surface on silicon carbide using small diameter grinding wheel

Journal of Mechanical Science and Technology - As an effective machining method for hard and brittle materials, ultrasonic-assisted grinding (UAG) was employed to manufacture microstructures on SiC...     

微孔砂轮射流冲击内外冷却技术在钛合金磨削中的应用研究

论述了钛合金材料理化特性和导致磨削加工困难的原因;阐述了冷却液在磨削中的基本作用;描述了微孔砂轮射流冲击内外冷却机理;给出了微孔砂轮射流冲击内外冷却磨削钛合金零件表面质量和砂轮表面形貌电子扫描分析报告;指出微孔砂轮射流冲击内外冷却新工艺最大限度地发挥了冷却液的冷却、润滑和冲淋作用,有效地解决了磨削钛合金零件表面产生拉伤、烧伤和夥轮表面粘结等工艺难题.     

数控成形磨齿机砂轮截形计算

砂轮加工斜齿轮时,斜齿轮齿面法线与砂轮轴线相交。利用这一原理,首先根据斜齿轮方程,计算斜齿轮与砂轮的接触线,求得加工斜齿轮时的砂轮廓形;其次,考虑到实际加工砂轮时金刚轮半径的存在,对砂轮刃形部分和过渡曲线部分分别进行了半径补偿;最后,利用B样条曲线和de boor算法,根据插补步长要求,运用时间分割插补算法,得到金刚轮加工砂轮时的插补点,给出了计算实例,并对砂轮廓形进行了拟合。     

磨床砂轮架设计与制造研究

就磨床的砂轮架在设计、制造、装配诸方面进行了比较详细、系统的研究与分析,揭示了磨床砂轮架中各零件之间的相互内在联系,指出了砂轮架设计、制造中如何对各种零件性能相互进行配合,从而满足不同性能的要求。     

Determining the optimum process parameter for grinding operations using robust process

We applied combined response surface methodology (RSM) and Taguchi methodology (TM) to determine optimum parameters for minimum surface roughness (Ra) and vibration (Vb) in external cylindrical grinding. First, an experiment was conducted in a CNC cylindrical grinding machine. The TM using L ₂₇ orthogonal array was applied to the design of the experiment. The three input parameters were workpiece revolution, feed rate and depth of cut; the outputs were vibrations and surface roughness. Second, to minimize wheel vibration and surface roughness, two optimized models were developed using computer-aided single-objective optimization. The experimental and statistical results revealed that the most significant grinding parameter for surface roughness and vibration is workpiece revolution followed by the depth of cut. The predicted values and measured values were fairly close, which indicates (R _Ra ² =94.99 and R _Vb ² =92.73) that the developed models can be effectively used to predict surface roughness and vibration in the grinding. The established model for determination of optimal operating conditions shows that a hybrid approach can lead to success of a robust process.     

Research on the technology for outer race elliptical groove grinding with basin-like grinding wheel

A new grinding method that outer race elliptic track in ball basket constant velocity joint is ground by means of basin-like grinding wheel is proposed herein. Aiming at the grinding process with basin-like grinding wheel, the paper establishes the mathematical model, optimizes the parameters by using restrictive random direction method, studies the processing principle in detail, and analyzes the machining errors. The simulation results indicate that the theoretical error of elliptical groove ground by basin-like wheel will be reduced to the level of 0.001 mm. Then, the grinding experiments of elliptical grooves with the basin-like grinding wheel were completed, and the measurements of the grooves by portable arm coordinate measuring machine were carried out, which validates the feasibility of this grinding technology.     

Research on elliptical groove grinding for plunging constant velocity joint with basin grinding wheel

The theoretical error of elliptical groove in outer race of plunging constant velocity joint ground by finger grinding wheel is about 0.004 mm. In order to decrease the error, a new grinding method with basin grinding wheel is proposed. When we optimize the design parameters, the basin grinding wheel will avoid the problems that the feasibility and grinding accuracy are restricted by the interference of the head in the grinding process by means of finger grinding wheel, and can be used to ensure the machining precision and the sectional shape of the raceway to the greatest extent. Aiming at the grinding process with basin grinding wheel, the paper establishes the mathematical model, optimizes the parameters by using simplex algorithm, studies the processing principle in detail, and analyzes the machining errors. The simulation results indicate that the theoretical error for elliptical groove ground by basin grinding wheel will be reduced to 0.631 μm.     

Automatic compensation for grinding wheel wear by pressure based in-process measurement in wet grinding

This paper deals with an application to automatic compensation of grinding wheel wear by a pressure based in-process measurement method in wet grinding. A pressure sensor is set beside a grinding wheel with a small gap. When grinding fluid is dragged into the gap by the rotation, hydrodynamic pressure, which corresponds to the gap length and the topography, can be measured. No electromagnetic properties of the workpiece and grinding wheel affect measured results. This method is applied to a CNC surface grinding machine. The pressure distribution and the relationship between the pressure and the gap length are measured. The pressure is decreased with the increase of the gap length. Its dispersion is around 1% for 0.5 μm-wear of a grinding wheel with 250 μm grit size. The dimensional error of a workpiece using the feedback of the wear is less than the feeding step, for the compensation, of 1 μm.     

基于LabVIEW的砂轮磨粒检测

为了对砂轮的状态进行检测,利用高倍显微镜景深小的特点,基于聚焦融合原理,建立了一套砂轮检测的三维成像系统,此系统用COM组件将LabVIEW和Matlab紧密结合起来后进行联合编程,既利用了LabVIEW的硬件控制能力又利用了Matlab的算法实现能力.然后使用动态轮廓模型对所得到的磨粒轮廓进行了提取,并通过使用遗传算法来进行动态轮廓模型的演化计算.最后对磨粒进行了分析.     

有机磨削液在氮化硅陶瓷磨削过程中的清洗机理研究

通过一系列试验考察了不同有机物的乳液作为冷却液时金刚石砂轮磨削氮化硅陶瓷的堵塞效果.试验结果表明:短链有机物及烷烃作为磨削液时,金刚石砂轮磨削氮化硅陶瓷会发生堵塞,而包含较强极性基团的长链有机物可以很大程度地降低砂轮堵塞.其原因是烷烃在氮化硅陶瓷表面形成的非极性油膜对非极性的氮化硅磨屑产生较强的吸引而聚集在磨削区,进而导致砂轮堵塞.油膜表面具有一定的极性可以很大程度地缓解磨屑的积聚并降低堵塞现象的发生.通过对几种极性有机物的清洗效果进行分析,探讨了有机物的分子结构特征与其清洗性能的关系.     

A robust condition monitoring methodology for grinding wheel wear identification using Hilbert Huang transform

Grinding is a finishing operation performed to obtain the desired finish on the component. Wheel wear is one of the primary constraints in achieving the desired productivity in grinding. A new methodology is proposed for accurate and timely identification of wheel wear in cylindrical grinding using Hilbert Huang transform and support vector machine. During the grinding of EN31 carbon steel, the condition of the wheel and its wear was monitored with an accelerometer and power cell. Both vibration and power signals captured were used to identify the condition of the wheel and its wear. An exhaustive feature set is generated in the frequency and the time-frequency domain. Hilbert Huang transform, an adaptive time-frequency analysis technique, was used to extract the features of tool wear in the time-frequency domain. The first three IMF constituents were further chosen for feature extraction of statistical parameters based on their mean energy. Random forests algorithm was used to identify the relevant features. The methodology was validated with several grinding experiments and, is found to give an accuracy of 100% with both low and high cutting depths. The results indicated the robust and reliable wheel wear detection in cylindrical grinding with the use of relatively cheap sensors like accelerometers. The proposed method can be widely used in many applications in the industry where grinding is predominantly used as the finishing operation.