高速主轴在线动平衡控制策略与实验研究

针对高速主轴机械式电机驱动平衡装置存在错调、平衡时间长等对主轴旋转精度造成的破坏问题,采用影响系数法无线控制在线动平衡作为试验调控手段,并提出解决方法。搭建实验平台,利用平衡装置在手动平衡的条件下多次实验,针对质量块移动方式总结出质量块移动策略,并对该移动策略进行仿真和实验验证,通过实验效果选出最佳移动方案。结果表明:该移动策略设计合理,可准确调整质量块,平衡时间短,达到预期效果;利用影响系数法对主轴在线动平衡,振幅降低明显,平衡精度、效率提高,为高速机械主轴在线动平衡调控提供依据。     

利用偏最小二乘回归法对主轴热误差数值建模的研究

采用五点法测量了加工中心主轴系统的温度场和热误差数据,利用偏最小二乘回归法建立了两者的多元线性回归模型.经研究分析,该模型具有较强的预测能力和较为理想的精度,可以满足热误差实时补偿的需要.     

非导电超硬材料电火花磨削主轴电机变频调速电路的设计

主轴电机速度的控制是非导电超硬材料双电极同步伺服电火花磨削技术中的一个重要环节，它对非导电超硬材料电火花磨削的率高、精度、表面质量和加工成本等都有很大的影响。论文在对该加工技术的工作原理和特点等进行分析研究的基础上，设计出了其主轴电机变频调速电路，对该电路的主电路和驱动保护电路的设计原理、构成和工作特点等进行了研究，给出了该电路的计算机仿真结果。     

侧铣不可展直纹面模具原理性加工误差计算方法

分析了侧铣不可展直纹面模具的原理性加工误差的来源及特点，提出通过计算被加工表面各点到刀具旋转轴扫掠面的距离以确定误差分布，为刀位主动补偿和后续加工提供了依据。采用有限次离散和平面替代的方法求取点到曲面之间的距离，根据求解精度要求确定曲面最小离散次数，提高了计算效率，平面替代法将问题简化为可精确求解的点到平面的距离问题。实例通过与三坐标测量结果的对比验证了算法的可靠性。     

Thermomechanical modelling of oblique cutting and experimental validation

An analytical approach is used to model oblique cutting process. The material characteristics such as strain rate sensitivity, strain hardening and thermal softening are considered. The chip formation is supposed to occur mainly by shearing within a thin band called primary shear zone. The analysis is limited to stationary flow and the material flow within the primary shear zone is modelled by using a one-dimensional approach. Thermomechanical coupling and inertia effects are accounted for. The chip flow angle is determined by the assumption that the friction force on the tool face is collinear to the chip flow direction. At the chip–tool interface, the friction condition can be affected by the important heating induced by the large values of pressure and sliding velocity. In spite of the complexity of phenomena governing the friction law in machining, a reasonable assumption is to consider that the mean friction coefficient is primarily function of the average temperature at the tool–chip interface. Comparisons between model predictions and experimental results are performed for different values of cutting speed, undeformed chip thickness, normal cutting angle and inclination angle. A critical study is presented in order to show the influences of the input parameters of the model including the normal shear angle, the thickness of the primary shear zone and the pressure distribution at the tool–chip interface. The model permits to predict the cutting forces, the chip flow direction, the contact length between the chip and the tool and the temperature distribution at the tool–chip interface which has an important effect on tool wear.     

Fine grinding of silicon wafers: effects of chuck shape on grinding marks

Silicon wafers are used for production of most microchips. Various processes are needed to transfer a silicon ingot into wafers. With continuing shrinkage of feature sizes of microchips, more stringent requirement is imposed on wafer flatness. Fine grinding of silicon wafers is a patented technology to produce super flat wafers at a low cost. Six papers on fine grinding were previously published in this journal. The first paper discussed its uniqueness and special requirements. The second one presented the results of a designed experimental investigation. The third and fourth papers presented the mathematical models for the chuck shape and the grinding marks, respectively. The fifth paper developed a mathematical model for the wafer shape and the sixth paper studied machine configurations for spindle angle adjustments. This paper is a follow up of the above-mentioned work. A mathematical model to predict the depth of grinding marks for any chuck shape will be first developed. With the developed model, effects of the chuck shape (as well as the wheel radius) on the depth of grinding marks will be studied. Finally, results of pilot experiments to verify the model will be discussed.     

Bearing load analysis and control of a motorized high speed spindle

Angular contact ball bearings are the most popular bearing type used in the high speed spindle for machining centers. Because the bearing load is increased rapidly with the raised spindle speed due to the centrifugal force and temperature raise, proper initial preload and especially operating-induced load control of the angular ball bearing is important to the rigidity, accuracy and life of the spindle. The bearing layout, preload mechanism an on-line load bearing control are discussed in this paper. The management of the centrifugal force and thermally-induced bearing loads is especially emphasized. An active bearing load monitoring and control mechanism that consists of an integrated strain-gage load cells and piezoelectric actuators has been developed and tested. This active control and monitoring mechanism on-line adjusts the bearing load according the cutting conditions. Experiments were conducted to identify the proper initial bearing preload range. Optimal preload for the lowest bearing temperature raise existed for a specified spindle speed. The optimum preload, however, should be raised when the operational speed is increased.     

DT360型倍捻机的改造及倍捻丝生产技术

通过对DT360倍捻机的原理及结构进行分析,研究其设计思路,提出了倍捻机的技术改造方法和维修技巧,实现了维修备件国产化,同时阐述了倍捻丝的生产技术,列出了生产中常见问题的处理措施,为倍捻机的设计、维修和使用等提供了参考。     

转子辅助槽对高速电主轴齿槽转矩的影响机理研究

针对高速永磁同步电主轴中永磁体与有槽铁心相互作用产生的齿槽转矩过高,从而导致电主轴产生振动与噪声的问题,通过在转子齿上开辅助槽来优化电主轴结构.以一台FL系列永磁同步电主轴三相星接Y型电机为模型,利用Ansoft软件对它进行运动仿真和磁场瞬态分析,得到了能有效削弱电主轴齿槽转矩的转子齿辅助槽设计方案.研究结果表明,在转...     

包缠复合纱摩擦纳米发电机的制备及其电学性能

为制备基于涤/棉与导电锦纶长丝包缠复合纱的摩擦纳米发电机,以涤/棉混纺纱为皮层,导电锦纶长丝为芯层,通过空芯锭花式加捻技术,将涤/棉混纺纱均匀包缠在导电锦纶长丝上,得到基于复合纱的摩擦纳米发电机.通过研究基于包缠复合纱的摩擦纳米发电机的电量输出性能,结果表明:该摩擦纳米发电机具有优异的电学能量输出性能,其电量输出值随着...