虚拟仿真技术在数控加工编程教学中应用研究

分析了数控编程课程教学的特点,讨论了数控虚拟仿真软件的分类及特点,并介绍了虚拟仿真软件在数控加工编程课程教学实践中的应用,最后讨论了数控虚拟仿真软件应用于教学中存在的优点和不足。     

AZ31镁合金热轧制工艺及数值模拟研究

针对AZ31镁合金平板的轧制过程进行试验研究,通过控制温度及不同道次的压下率等工艺条件,最终将36mm厚的镁合金铸锭,压制成厚度为1mm的板材.同时运用MSC.Marc软件,采用显式弹塑性有限元法对AZ31镁合金平板的轧制过程进行热-机耦合三维数值模拟.对轧件在轧制过程的金属流动、温度、应力及应变分布等特点进行分析,并与实际试验结果进行对比,验证了模拟结果的准确性.     

A virtual injection molding system based on numerical simulation

CAD and CAE have now become very popular in injection molding development. Integration with virtual reality is a new boost to these fields. This paper presents a research effort targeting the creation of a desktop-based, low-cost and independent virtual injection molding system, which is implemented based on the techniques such as virtual reality, finite element analysis, motion simulation and scientific visualization. With the stereoscopic display of the mold design and motion, the system provides engineers a cohesive view of mold structure and assembly. And by analyzing the numerical CAE results, the possible faults during molding process can also be highlighted. With this integration, the overall system would be a new powerful tool to mimic the real process of injection molding and evaluate various influences from product design to manufacturing, capable, therefore, of improving the moldability and the quality of molded products.     

一种基于数值模拟的金属粉末轧制力能参数计算方法

对金属粉末轧制的成形特点进行分析。基于可压缩连续体力学对金属粉末轧制的有限变形弹塑性本构模型进行推导,并编制了计算模块,利用该模块对铝粉轧制过程进行数值模拟。分析成形区域的特征,结果表明压实区所对应的等效应力、等效应变与相对密度都达到最大值,进入稳定轧制阶段后轧制力趋于平稳。结合对轧制变形的区域划分,根据应力、应变及密度等参数的分布,确定咬入角和中性角的位置。对轧制力和相对密度的实验和模拟结果进行对比分析,表明所提出的理论模型及计算模块稳定可靠。     

钻井稳定器Y形密封圈的数值仿真研究

稳定器在石油钻井中对井眼轨迹的控制具有重大作用,它的正常运行要求其内部的Y形橡胶密封圈对液压油进行有效地密封.通过建立稳定器中Y形密封圈的非线性有限元分析模型,对唇外径分别为70 mm和115 mm两种类型的Y形密封圈进行了分析,得到唇外径为70 mm及115 nn的两种密封圈其,临界工作压力分别为14.69 MPa和15.53 MPa.最后通过等效Von Mises应力对所得临界工作压力进行校核,结果表明通过最大接触压力判据所得数值是正确的.所得研究成果可对控制稳定器Y形密封圈密封失效提供理论依据,为提高稳定器的可靠性从而提高石油钻探效率提供指导.     

基于Virtools的机械零部件虚拟装配的仿真研究

本文首先通过三维绘图软件对机械产品的零部件进行实体建模,然后利用3Ds max和Virtools技术的交互性设计了各零部件的动态装配,最终实现了机械产品零部件虚拟装配的动态演示。构建该平台不仅可以节省开发时间和成本,还可大大减少对资源的利用,使虚拟现实技术更加实用。     

A comparison of asymptotic and numerical rolling models for quasi-three-dimensional problems

This study compares two quasi-three-dimensional steady-state rolling models. The validity of both models assumes that the ratio of strip half-thickness to contact length is small. Thickness to length ratios less than 0.3 are acceptable, and sometimes the models work well beyond this limit. One model is a finite element calculation which uses one layer of elements through the strip half-thickness. The other is an asymptotic approach which includes both first- and second-order terms. For this study, both models use the relative slip friction model at the roll/sheet interface and a hyperbolic sine constitutive relationship between stress and strain rate.An important feature of the solution is that it is very sensitive to the spread. Small changes in spread often lead to significant changes in stresses. The predicted spreads are always small and their magnitudes are typical of those found in practice. However, the spreads found by the models do not always agree. Results show that when the entry and exit forces for the two models coincide, the stress distributions in the roll bite are in good agreement.     

Kinematics analysis and numerical simulation of a manipulator based on virtual prototyping

Manipulator kinematics refers the analytical study of the motion of manipulator, such as positions, velocities, and accelerations of the links of a manipulator. As formulating the suitable kinematics models for a manipulator is very crucial for analyzing the behavior of manipulators and light weight design of manipulators, many researches have been focused on it in recent decades with a result of many valuable contributions. However, current researches always focus on rigid manipulator, while the manipulator is always a rigid-flexible coupling multibody system, which can affect the accuracy of kinematics analysis and numerical simulation. This paper proposed a model of kinematics analysis of manipulator based on rigid-flexible coupling virtual prototyping. After a model of manipulator kinematics based on the D-H method was proposed, rigid-flexible coupling virtual prototyping-based kinematics simulation and numerical simulation was then put forward. The kinematical experiment is carried out based on manipulator physical prototyping, which demonstrates that the accuracy of the kinematics calculation and the rationality of design based on rigid-flexible coupling virtual prototyping. The design of a five-degrees-of-freedom manipulator is given as an example, which demonstrates that the methodology is obviously helpful to manipulator design.     

A multi-step progressive fault diagnosis method for rolling element bearing based on energy entropy theory and hybrid ensemble auto-encoder

It is meaningful to efficiently identify the health status of bearing and automatically learn the effective features from the original vibration signals. In this paper, a multi-step progressive method based on energy entropy (EE) theory and hybrid ensemble auto-encoder (HEAE), systematically blending the statistical analysis approach with the deep learning technology, is proposed for rolling element bearing (REB) fault diagnosis. Firstly, a preliminary detection about the REB health status is performed by the statistical analysis technique integrated with the EE theory. Secondly, if fault exists in REB, a new HEAE is constructed based on denoising auto-encoder and contractive auto-encoder to strengthen the feature learning ability and automatically extract the deep state features from the raw data. Subsequently, a modified t-distributed stochastic neighbor embedding (M-tSNE) algorithm is developed to achieve the features reduction to further improve the diagnosis efficiency. Finally, the low-dimensional representations after features reduction are as the inputs of softmax classifier to recognize the fault conditions. The proposed method is applied to the fault diagnosis of REB. The results confirm the effectiveness and superiority of the proposed method, and it is more suitable for the actual engineering applications compared with other existing methods.     

ISG混合动力汽车控制策略研究及仿真

混合动力汽车在节能减排方面体现了巨大的优势,成为当前的研究热点.对于混合动力汽车而言,制定合适的控制策略是实现整车良好性能的关键.介绍了用于ISG型并联混合动力汽车的几种控制策略,详细分析了各种控制策略的控制思想,并通过仿真对各种控制策略下汽车的性能进行了对比研究.     

高颈法兰封闭轧制的数值模拟研究

基于DEFORM有限元软件建立了高颈法兰封闭轧制过程的仿真模型,对整个周期的动态轧制过程进行数值模拟分析,分别分析了驱动辊转速、芯辊进给速度对轧制过程以及轧制力的影响规律,并获得了工艺参数的优化指标。研究结果表明,计算机数值模拟对优化工艺参数、提高轧制效率具有重要的意义。     

A hybrid supervisory control approach for virtual production systems

With the development of computer technology, the anticipated extensive use of virtual production systems (VPSs) in the future has encouraged its intensive research recently. However, a limited amount of research has been made on its efficient control. In this paper, a hybrid supervisory control approach based on autonomy and coordination is proposed for VPSs to enhance the efficiency of control. Its three primary advantages are: (1) application of supervisory control theory, which can efficiently obtain the desired property through closed-loop feedback; (2) use of hybrid control structure combining hierarchical and distributed ones, which can avoid the exponential explosion of state space due to synthesis of models; and (3) utilization of autonomous and coordination mechanisms, which can keep the balance of local quick response and global optimization. A case study is used to illustrate how to implement the proposed approach, and is finally analyzed and simulated by an integrated tool named UPPAAL.     

Complete modeling and parameter optimization for virtual ring rolling

Virtual manufacturing, usually consisting of complete modeling and optimization, of a manufacturing process has recently become one of the research trends in the area of process designing and selection. With the aim to realize complete modeling of a ring rolling process, a complex actuation mechanism model of a heavy radial-axial ring rolling machine has been established in this study. Moreover, a self-modified computer program for controlling the real-time movements of two guide rollers and two conical rollers in a ring rolling process has been developed. An optimization objective function has been proposed for saving the rolling time, in which the slip rate is regarded as the state variable. With this function, the virtual ring rolling process for producing a titanium alloy ring with a rectangular section has been successfully conducted using the finite element method. The simulation results are in good agreement with the experimental findings. Thus, the feasibility of the proposed method has been demonstrated. The computational result also reveals that the proposed optimization method can reduce the rolling time by about 28%.     

基于虚拟仪器的冷轧带钢板纵向厚度监测策略研究

为了改善本钢冷轧厂1676mm酸洗一冷连轧联合机组的板带质量,提出了采用虚拟仪器技术构成监测系统的方法。在详细分析影响板带材纵向厚度和板凸度的各种因素基础上,采用基于LabVIEW的虚拟仪器构建方法开发了板带厚度和板凸度的监测软件系统,能够对冷轧厂现场的实际工况与设计系统实际测试结果进行对比分析。在轧制过程中,系统可以准确实时的完成对所需信号的监测,并进行实时显示等相关处理工作,实现了对监测数据的协同处理。     

车间生产调度系统的虚拟仿真研究

阐述车间生产调度问题及其特点,详细分析仿真调度的原理和特点;并结合车间调度的具体情况,提出一套车间生产调度系统虚拟仿真的解决方案.     

滚珠丝杠副制造中的"球心论"技术

滚珠丝杠副的运转平稳性(手感)是衡量产品质量的重要指标之一,是行业内长期以来所关注和亟待解决的问题,为此把滚珠丝杠副承载时钢球在滚道内产生弹性接触变形前后的球心位置变化作为研究对象建模,合理地改进统筹了设计参数,并采取有效的工艺措施,突破了滚道圆弧半径R的成型磨削和测量技术难点,成功地提升了滚珠丝杠副系列产品的品级。     

High-efficiency automated line for precise cold rolling of bearing rings

Russian Engineering Research -     

三环滚动转子压缩机的设计

对三环旋转压缩机的工作原理、结构设计作了介绍。并对压缩机样机的研制与试验也作了说明与分析，指出了试验中的不足。     

光电转塔虚拟装配工艺规划及仿真技术研究

本文以光电转塔为研究对象,在对虚拟装配中的装配路径规划基本流程进行分析的基础上应用虚拟装配技术,开发出一个实用的可视化工艺规划系统,对光电转塔装配过程进行虚拟装配仿真,并取得良好的效果。     

Flow pattern identification for gas-oil two-phase flow based on a virtual capacitance tomography sensor and numerical simulation

Gas-oil two-phase flow is widely encountered in oil exploitation and transportation pipelines. It's complex and transient changes of flow regimes present a great challenge for accurate and real-time measurement. As a non-invasion and real-time measuring method, electrical capacitance tomography (ECT) is suitable for the transient measurement of non-conductive gas-oil flow. However, the highly random and nonlinear nature of multiphase flow make it difficult and limited to investigate the flow parameters based on either static or dynamic measurement. In this research, the whole process of dynamic measurement of ECT applying in gas-oil two-phase flow is thoroughly studied, including simulation calculation, experimental validation and comprehensive data analysis. A simulation approach by coupling the flow and electrostatic field is proposed based on a virtual ECT sensor, in order to monitor the gas-oil two-phase flow characteristics. Based on FLUENT and COMSOL platform, the numerical simulation under six typical flow patterns in a horizontal pipe is carried out. Combining the visualized image generated by ECT measurement and the theory of flow pattern transition, the formation mechanism and structural characteristics of different gas-oil flow patterns are analyzed in detail. Furthermore, this research attempts to analyze the signal fluctuation characteristics caused by flow pattern change, in order to access more in-depth flow information implied in the original capacitance data, via time-series analysis as well as frequency domain analysis based on Flourier Transform. At last, a series of dynamic experiment is conducted to verify the feasibility of the simulation and data analysis approach. The experiment focuses on the flow pattern transition, gas-liquid dynamic characteristics and noise influence in the actual process. It can be concluded from the results of simulation and experiment tests, combining the visualized images and the dynamic characteristics of capacitance signals can make it more effective and intuitive for flow pattern identification, which might be used for the online measurement in real-industry process.