基于任务请求的简单柔性装配系统设计和实现

针对小批量、多品种产品的装配特点,使用紊流输送技术,提出并实现了一种基于任务请求的简单柔性装配系统的设计方法.该简单柔性装配系统由柔性装配线、控制系统、监控和调度系统3部分组成,为小批量、多品种产品装配线的建设提供了一个柔性化的解决方案.     

雷达T/R组件柔性装配系统设计与实现

针对手工装配雷达T/R组件质量和效率较低的问题,设计了雷达T/R组件柔性装配系统。该系统以紊流输送技术为基础,由柔性装配线体和监控调度系统组成,调度系统根据生产任务,结合现场数据模型和工艺数据模型自动生成生产数据模型并按调度规则进行调度,工序与工位之间多对多的工艺约束关系使得系统具有更大的柔性。该系统经过实际应用,表明...     

液压锥阀内部流场的可视化分析

利用Fluent计算流体软件对液压锥阀的内部流场进行分析,经对阀芯不同开口量的可视化分析,采用标;住紊流模型模拟了内部流体的流动状态及漩涡的产生区域,并对其稳态液动力进行了分析,可为阀的整体性能和结构优化提供参考依据：     

用于汽车座椅滑轨生产线的钢球自动装配装置

介绍了一种汽车座椅滑轨钢球装配装置,可通过钢球输送供料、间隔条输送供料、钢球和间隔条装配等机构,实现汽车座椅滑轨装配过程中的钢球、间隔条等零件的自动装配过程。本装置结构紧凑、自动化程度高,能够有效保证各钢球及间隔条在座椅滑轨中的准确装配,同时可根据后道工序对座椅滑轨滑移力检测的结果,系统自动调整,选择不同直径的钢球进行装配。     

轮胎轮毂装配线仿真设计研究

文章所设计的工业机器人装配线是轮胎轮毂装配线。文章对装配线整体结构进行设计,对输送流程进行了分析,然后通过机器人工作环境和必要参数去对机械臂的受力得出范围,并且对装配的动作形式进行设计,选择适合的机器人类型、控制器类型以及电机和减速器类型。     

基于SolidWorks的黏土输送泵转阀的设计

针对流动性差的黏土材料的输送工艺,提出一种采用三通转阀结构实现连续稳定输送黏土的泵送设备。利用SolidWorks软件实现黏土输送泵模型的建立,根据实际工况需要设计该泵的输送传动装置,该装置采用了三通转阀。利用SolidWorks的高级建模功能和装配功能,对各零部件进行设计并装配,利用SolidWorks的演示功能描述了该设备装配后的运行状态,同时也为验证设计和装配的合理性提供了一定的参考依据。     

新型折板式升降机

根据电子工业装配生产线连续输送的特点,我院设计了Z型、C型折板式升降机,用于装配生产线输送电视机、收录机及各种成箱物件,能把上下楼层的水平装配生产线联系起来。也可单独用于上下输送货物,如仓库的堆     

自动选送钉装备的设计

针对飞机装配铆接工序中铆钉输送的工艺过程和技术要求,研制了一种铆钉自动分选输送装备。对该装备中的关键机械结构进行了详细设计,实现了飞机铆接过程中铆钉的自动化分选、输送,降低了劳动强度,提高了劳动生产率。     

螺旋槽水润滑橡胶合金轴承沙粒侵蚀磨损研究

螺旋槽水润滑橡胶轴承橡胶面的破坏除了与运动轴直接接触造成磨损外,水中泥沙颗粒等污染物对水润滑橡胶的侵蚀磨损也是影响水润滑橡胶工作面的主要破坏方式。对液-固两相流中固体颗粒的受力情况进行分析;借助于Finne磨损基本数学模型,对不同转速、不同大小沙粒和水组成的流场进行分析,得到内部颗粒随液态流场变化的趋势;对中高转速下颗粒对壁面磨损的过程和位置进行初步的预测。结果表明,在不同转速下,不同粒子对橡胶面不同位置的侵蚀磨损是显著不同的:低转速下,接近层流状态时,对承载面的磨损较大;高转速下,流体呈现紊流状态,并在导流槽内出现独立的漩涡现象,导致颗粒在漩涡内聚集,从而造成漩涡面的磨损侵蚀较大。螺旋槽结构导致流场内漩涡出现,对于排污具有较好的作用。     

长尾夹自动装配系统上料卸料同步装置研究

针对长尾夹自动装配系统装配过程中上料卸料的欠缺和低效等问题,对自动装配系统上料卸料机构进行了研究,提出了新型的间歇性双段推板上料卸料同步装置,利用该同步装置实现了对未装配夹体进行上料和对已装配好的长尾夹进行卸料。利用西门子公司的S7-200系列PLC控制器对长尾夹装配机进行了上料卸料、输送、装配的系统控制,实现了过程中的自动装配。利用Matlab软件中的Simulink仿真工具对自动装配系统的上料卸料气缸进行了动力学仿真,通过仿真确定了上料卸料气缸在充气推出过程中的各个参数值,得出了工作气压最优值和平台的装配效率。研究结果表明,上料卸料同步装置装配在气缸压强为0.2 MPa,上料卸料时间为0.693 s时的工作效率最高,容错率更低,可有效取代人工上料卸料。     

A dynamic global subgrid-scale model for large eddy simulation of scalar transport in complex turbulent flows

In the present study, a dynamic global subgrid-scale eddy diffusivity model for large eddy simulation of scalar transport in complex turbulent flows is proposed by generalizing the dynamic global subgrid-scale eddy viscosity model [Phys. Fluids, 18 125109 (2006) and Phys. Fluids, 22 075106 (2010)]. The global model coefficient in the subgrid-scale model is determined by a dynamic procedure based on the Germano identity such that the model coefficient is globally constant in space but varies only in time. Large eddy simulations of passive scalar transport in turbulent channel flow, turbulent boundary layer, and turbulent ribbed channel flow are conducted and the proposed model shows an excellent performance for all the flows considered. Since the proposed model requires no ad hoc clipping and/or averaging over a homogeneous direction, it can be readily applied to large eddy simulation of scalar transport in complex turbulent flows.     

Low reynolds number κ-ε modeling with improved ε equation

A series of κ-ε model modification has been carried out using DNS data to include near wall effects. Though these methods aided by DNS data open new ways of turbulence modeling, the κ-ε turbulence models still have shortcomings in predicting turbulent flows for various Reynolds numbers and various geometric conditions. Therefore a new κ-ε models with improved dissipation rate of turbulent kinetic energy equation and the damping function for eddy viscosity model is proposed. The new dissipation rate equation is based on the energy spectrum and magnitude analysis. The damping function for eddy viscosity is also based on the dissipation rate length scale distribution near the wall and the DNS data. The new κ-ε model is applied to fully developed turbulent flows in channels and pipes with a various Reynolds numbers. Predictions show that the proposed model represents properly the turbulence properties in all turbulent regions over a wide range of Reynolds numbers.     

Large eddy simulation of turbulent premixed flame in turbulent channel flow

Large eddy simulation of turbulent premixed flame in turbulent channel flow is studied by usingG-equation. A flamelet model for the premixed flame is combined with a dynamic subgrid combustion model for the filtered propagation flame speed. The objective of this work is to investigate the validity of the dynamic subgridG-equation model to a complex turbulent premixed flame. The effect of model parameters of the dynamic subgridG-equation on the turbulent flame speed is investigated. In order to consider quenching of laminar flames on the wall, wall-quenching damping function is employed in this calculation. In the present study, a constant density turbulent channel flow is used. The calculation results are evaluated by comparing with the DNS results of Bruneaux et al.     

On the large eddy simulation of high prandtl number scalar transport using dynamic subgrid-scale model

The present study investigates passive scalar transport using an eddy viscosity/diffusivity model in turbulent channel flow with Prandtl number range 1-10. Dynamic subgrid-scale model (DSM) was applied to the transport equation for passive scalar to determine the eddy diffusivity dynamically. To assess the feasibility of the DSM model applied for passive scalar,a priori test on direct numerical simulation data was conducted and the results are compared with those obtained from a large eddy simulation that uses DSM modela posteriori. As the Prandtl number increases, the discrepancy in subgrid-scale (SGS) heat flux amplifies but the shape of SGS temperature dissipation profiles shows reasonable agreement. This suggests that energy transfer between resolved and subgrid-scales are reasonably predicted regardless of the accuracy in SGS heat flux vectors. Whilea priori test shows that SGS turbulent Prandtl number changes significantly with Prandtl number, the actual LES results are found to be insensitive to Prandtl number away from the wall. Thus, the DSM model has some limitations in the prediction of high Prandtl number flows.     

Large eddy simulation of turbulent premixed combustion flow around bluff body

Large eddy simulation (LES) of turbulent premixed flame stabilized by the bluff body is developed by using sub-grid scale combustion model based on the G-equation describing the flame front propagation. The basic idea of LES modeling is to evaluate the filtered-front speed, which should be enhanced in the grid scale by the scale fluctuations. The dynamic sub-grid scale models newly introduced into the G-equation are validated by the premixed combustion flow behind the triangle flame holder. The objective of this study is to investigate the validity of the dynamic sub-grid G-equation model to a complex turbulent premixed combustion such as bluff body stabilized turbulent premixed flames for realistic engineering application. A new turbulent flame speed model, introduced by the sub-grid turbulent diffusivity and the flame thickness, is also proposed and is compared with the usual model using sub-grid turbulent intensity and with the experimental data. The calculated results can predict the velocity and temperature of the combustion flow in good agreement with the experiment data.     

Turbulent heat transfer characteristics in compound channels with gap

To examine the characteristics of turbulent flow and heat transfer about the compound channel with gap, the present study has performed a numerical analysis by using large eddy simulation (LES). Our first aim was to analyze the cause of pulsating flow by investigating the turbulent flow through the unsteady analysis of compound channel. Next, to understand the correlations between gap width and heat transfer enhancement, we tried to verify the enhancement effect of heat transfer when a gap exists within the compound channel. From this numerical analysis, we could see that the lateral velocity occurs periodically around the gap and this is developed in the pulsating flow. The pulsating flow has generated a strong turbulent flow mixing within the compound channel. And the turbulent flow mixing in the pulsating flow plays an effective role of enhancing heat transfer effect by making the fluid temperature uniformly within the compound channel.     

基于涡流传感器阵列的火车轮在役自动检测系统设计

提出一种基于涡流传感器阵列的火车轮自动在役检测系统,为铁路运输提供一种安全的运营手段。     

Large eddy simulation of turbulent premixed combustion flows over backward facing step

Large eddy simulation (LES) of turbulent premixed combustion flows over backward facing step has been performed using a dynamic sub-grid G-equation flamelet model. A flamelet model for the premixed flame is combined with a dynamic sub-grid combustion model for the filtered propagation of flame speed. The objective of this study is to investigate the validity of the dynamic sub-grid G-equation model in a complex turbulent premixed combustion flow. For the purpose of validating the LES combustion model, the LES of isothermal and reacting shear layer formed at a backward facing step is carried out. The calculated results are compared with the experimental results, and a good agreement is obtained.     

Evaluation of subgrid-scale models in large-eddy simulations of turbulent flow in a centrifugal pump impeller

The current research of large eddy simulation (LES) of turbulent flow in pumps mainly concentrates in applying conventional subgrid-scale (SGS) model to simulate turbulent flow, which aims at obtaining the flow field in pump. The selection of SGS model is usually not considered seriously, so the accuracy and efficiency of the simulation cannot be ensured. Three SGS models including Smagorinsky-Lilly model, dynamic Smagorinsky model and dynamic mixed model are comparably studied by using the commercial CFD code Fluent combined with its user define function. The simulations are performed for the turbulent flow in a centrifugal pump impeller. The simulation results indicate that the mean flows predicted by the three SGS models agree well with the experimental data obtained from the test that detailed measurements of the flow inside the rotating passages of a six-bladed shrouded centrifugal pump impeller performed using particle image velocimetry (PIV) and laser Doppler velocimetry (LDV). The comparable results show that dynamic mixed model gives the most accurate results for mean flow in the centrifugal pump impeller. The SGS stress of dynamic mixed model is decompose into the scale similar part and the eddy viscous part. The scale similar part of SGS stress plays a significant role in high curvature regions, such as the leading edge and training edge of pump blade. It is also found that the dynamic mixed model is more adaptive to compute turbulence in the pump impeller. The research results presented is useful to improve the computational accuracy and efficiency of LES for centrifugal pumps, and provide important reference for carrying out simulation in similar fluid machineries.