Dynamic design for motorized spindles based on an integrated model

With increasing popularity in high-speed machining for its high efficiency, motorized spindles have been widely utilized in modern production facilities. Due to the combination of tools and built-in motors, the dynamic characteristics of motorized spindles are more complex compared with conventional spindles, and it is becoming necessary for engineers to thoroughly realize the influences of the system parameters to the system dynamics with considering the multi-physics coupling property. This paper presents an integrated model to study the electro-thermo-mechanical dynamic behaviors of motorized spindles. The integrated model consists of four coupled submodels as follows: bearing, built-in motor, thermal, and shaft model. Based on the proposed model, a design flow chart is developed and six design parameters are identified. The integrated model is validated experimentally and a design sensitivity analysis of the six parameters is then conducted based on a 170MD15Y20 type spindle. The results show that the integrated model is capable of accurately predicting the dynamic characteristics of motorized spindles, and the sensitivities of the six design parameters to the nature frequencies of the spindle system are obtained with and without the influence of the multi-physics coupling property. The coupling relationship among the electrical, thermal, and mechanical behaviors of the spindle system becomes clear from the results.     

Molecular dynamics in chlorinated butyl rubber containing organophilic montmorillonite nanoparticles

The dynamic mechanical loss tangent (tanδ) of chlorinated butyl rubber (CIIR) shows an asymmetrical double-peak structure with a shoulder on the low-temperature side and a maximum on the high-temperature side, which are attributed to local segmental motion and Rouse modes, respectively. To study the effect of nanoparticles on these two different modes of molecular motion, organophilic montmorillonite nanoparticles (OMMT) were incorporated into CIIR. With the increase of OMMT weight fraction, a filler network is formed and becomes more and more compact in the CIIR matrix, which exerts significant effect on the molecular dynamics of CIIR. The maximum and the shoulder of the tanδ peak are both suppressed by the filler network, but the maximum is suppressed to a higher extent and finally even becomes lower than the shoulder at high filler loading. The temperature position of the maximum is also shifted toward lower temperature with the formation of the filler network, while that of the shoulder remains nearly constant. These phenomena can be interpreted in terms of the different restriction extents of the filler network on the different modes of molecular motion.     

面向未来 2010上海世博会世博演艺中心设计

2010上海世博会世博演艺中心设计围绕主场馆演出空间设置相关的文化娱乐衍生功能,形成大型的、独特的文化娱乐聚集区。主场馆的规模可以调节,主观演区灵活多变的功能配置和完备的技术系统,确保了多功能、高规格的演出需求。配套的文化休闲娱乐空间,构成对演艺中心功能的补充,引导不同目标顾客群的附带消费,拓展了演艺中心的文化外延,演艺中心力求营造大众的、高雅的、时尚的文化氛围,激发整个园区的动感活力。     

基于网络协同设计的面向装配信息模型研究

提出一种为面向装配设计服务的网络协同设计体系结构和网络环境下面向装配设计的建模体系，该结构集产品协同设计、装配设计、装配规划、装配系统设计于一体。建立装配关系矩阵、装配信息矩阵、装配信息链表，给出了详细的协同机制和算法。该数据结构能方便地进行数据的插入、查询和编辑等工作，产品设计和装配规划能够在网络协同设计中和面向装配设计系统中同步地、智能地和完整地进行。     

基于WiFi的无线浪高数据采集系统的设计

在海洋工程实验室现场数据采集过程中,由于测试点分散、实时性能要求较高、现场布线相对繁琐,提出一种基于WiFi的无线浪高数据采集系统。该系统主要由数据采集模块、单片机控制模块、无线WiFi模块以及上位机系统构成。采集的浪高信号经过电压偏置和低通滤波后由单片机控制器进行AD转换,然后通过无线WiFi模块输出数据。上位机系统通过无线AP点接收数据,再利用分析软件对数据进行分析和显示动态数据。在实验水池中,搭建由造波机、数据采集系统、无线接入点、上位机组成的实验系统来采集实时的浪高数据并验证系统数据传输的稳定性和数据通信的可靠性。通过实验证明,该系统可以实时采集浪高数据,具有传输速率快、可靠性高、实时性好的特点。     

合成系统氢氮比异常的原因及对策

介绍合成系统氢氮比异常的原因分析及处理措施。     

Weighted sparsity-based denoising for extracting incipient fault in rolling bearing

Given that the incipient fault is too weak for extraction, a novel approach that is based on sparse optimization is proposed for incipient fault diagnosis. The proposed optimization method consists of three steps: First, autocorrelation analysis is utilized to filter broadband random noise. Then, the weighted sparsity-based denoising method is proposed to extract periodic impulses. The prior knowledge that periodic impulses are sparse is used to constitute a penalty term; thus a novel weighted sparse optimization model is established. The majorization-minimization method is used to solve the optimization model. The high-pass filter in quadratic fidelity term is constructed by a Butterworth filter based on banded matrices, thus effectively improving computational efficiency. Lastly, the interval of periodic impulses, which corresponds to the fault frequency of rolling bearing, is obtained. Moreover, simulation and experimental results show that the proposed approach can successfully extract fault features from the signals of low signal to noise ratio.     

Dynamics modeling and modal experimental study of high speed motorized spindle

This paper presents a dynamical model of high speed motorized spindles in free state and work state. In the free state, the housing is modeled as a rotor with equivalent masses including bearing pedestals, motor stator and rear end cover. As a consequence, a double rotor dynamics can be modeled for high speed motorized spindles by a bearing element which connects the housing and bearing pedestals. In the work state, the housing is fixed and the system becomes a bearing-rotor dynamical model. An excitation-measurement test in the free state is designed to analyze the cross spectral density and auto spectral density of input and output signals. Then the frequency response function of system and coherence function of input and output signals which are used to analyze the inherent characteristics of the double- rotor model can be obtained. The other vibration test in the work state is designed to research the dynamical supporting characteristics of bearings and the effects from bearings on the inherent characteristics of the system. The good agreement between the experimental data and theoretical results indicates that the dynamical model in two states is capable of accurately predicting the dynamic behavior of high speed motorized spindles.