门座起重机臂架系统在起升动载激励下的动态特性研究

根据机械振动理论,对门座起重机臂架系统结构在起升动载激励下动力学特性进行研究,建立起重机起升机构的动力学模型,确定了起升机构在起动、制动工况下,钢丝绳系统弹性力的计算公式;运用ADAMS动力学软件,对臂架系统结构在起升过程时的动态响应进行仿真研究,为起升动载系数的选取提供一种新方法和理论依据.     

水电站大型桥式起重机起升机构结构形式和性能分析

以三峡1 200/125 t桥式起重机为例,分析了水电站大型桥式起重机起升机构的整体布置方案、主传动及速度控制系统、制动系统、减速器的固定形式、钢丝绳缠绕系统的结构形式和性能特点。     

基于MSC-ADAMS的某型起升机构建模及起升工况动力学仿真

为研究某型起升机构启动工况的动态特性,利用动力学软件MSC-ADAMS对其进行分析建模,采用离散刚体模拟钢丝绳结构,通过编制宏命令,分别得到了离散刚体结构、刚体间轴套力以及刚体与滑轮间的接触力模型,并针对多倍率滑轮系统,通过引入“等效钢丝绳”,构建了系统的仿真模型.通过对起升工况进行动力学仿真,得到机构的位移时间历程、...     

桥式起重机起升机构最大动张力的分析研究

建立了桥式起重机起升机构的动力学模型,通过模型推导出了振动引起的最大动张力计算公式,得出了钢丝绳的刚度与最大动张力的关系。在此基础上分析研究了受力钢丝绳的长度及滑轮组的倍率对振动引起的最大动张力的影响,为生产操作和设计选择提供了一定的理论基础。     

桥门式起重机起升机构设计

通过对起升滑轮组倍率、钢丝绳、电动机以及减速器与联轴器的选择对起升机构性能的影响分析,确定桥门式起重机起升机构各部件的参数与指标值,从而便于桥门式起重机的起升机构的设计。     

集装箱起重机多功能起升系统设计

起升系统是集装箱起重机的主要工作机构,通常具备起升或钢丝绳斜拉防摇的功能,而文中设计的多功能起升系统是对常规的集装箱起重机起升系统的升级和优化。通过合理设计、布置起升机构,整合升级防摇系统,使整个起升系统具备起升、倾转、回转、双向平移、主动防摇多种功能。能够满足日益增长的自动化精度需求,显著提高集装箱起重机可操作性、抗摇摆性、装卸效率,减轻司机的劳动强度。     

起重机起升故障的排除

一台QY25型汽车起重机在使用过程中,出现主起升机构有响声、起升无力(6倍率钢丝绳吊重16t时吊不起来) 的现象。 (1)起升机构有响声。据观察分析故障可能出在平衡阀上,该阀从意大     

RMG起升机构制动器的选择计算分析

对RMG起升机构制动器的工况做了简单介绍，分析了制动距离对司机安全操作的重要性，给出RMG起升机构制动距离的计算方法。     

汽车起重机起升机构的维修

现代汽车起重机多采用液压式起升机构。它由起升装置、驱动装置和控制装置3部分构成。起升装置由卷筒、卷筒离合器、卷筒制动器、卷筒轴、钢丝绳、吊钩和起升高度限位器等组成;起升驱动装置由起升液压马达及其减速器组成;起升控制装置由手动分配阀、离合器控制阀、液压助力缸、平衡阀及液压管路等组成。起升液压马达,可分为定量轴向柱塞型和变量轴向柱塞型两种。1.定量液压马达的维修 通过改变发动机的转速来控制卷筒转速,按制动的型式又可分为机械制     

200t桥式起重机起升机构的动力学仿真分析

对桥式起重机的起升机构进行动力学仿真分析,建立起升机构的动力学理论模型和振动微分方程,推导出起升工况下的动载系数;探讨了起升机构中柔性体钢丝绳的建模方法,并在ADAMS中建立起升机构的动力学仿真模型,进行仿真分析,验证理论推导的起升动载系数,分析机构中零部件的受力状况,为起重机整机的设计及分析时力的加载提供依据。     

Objective Characterization on the Dynamic Friction Coefficient of Disc Brake

As the most significant parameter for evaluating the friction state of disc brakes, the friction coefficient was characterized solely by its average and stability coefficient, which cannot accurately represent its dynamic variation characteristics during braking. In this article, a new characterization parameter set consisting of an overall and a partial characteristic parameters subset was established to characterize the dynamic variation in friction coefficient of disc brakes. Moreover, the influence of braking conditions on these new parameter sets was studied by tribological experiments. Several simulated braking experiments were carried out and the dynamic variation rules were observed. Secondly, a new characterization parameter set including eight parameters (mean value, stability coefficient, energy coefficient, end point of rapid rising, starting and end points of the up-tail, trend coefficient, and catastrophe coefficient) was established. Finally, the influence of initial braking velocity and braking pressure on these parameters and its mechanism was analyzed by braking experiments. It is concluded that the parameter set established in this article can be used to characterize the dynamic variation rules of the friction coefficient of disc brakes more objectively and comprehensively.     

升降式输送机起动及制动阶段动态特性分析

由于升降式输送机在输送启停过程中会产生惯性作用力,其作为横向载荷作用在丝杠升降机上,使得丝杠升降机中滚珠丝杠应力极值大幅度提升,通过ADAMS软件建立升降式输送机虚拟样机模型,并对启停过程进行动态特性分析,得到启停时间对动态特性的变化规律,提出了导向支撑轮机构以减小丝杠升降机应力极值。实践表明,通过导向支撑轮增加丝杠升降机伸出端的支撑,大大改善其受力状况并降低其应力极值,对于延长升降机的工作寿命,提高其工作可靠性具有参考意义。     

带式输送机纵向振动分析

通过对带式输送机的动力学现象，机理及运动规律的分析，建立了输送带的有限元力学模型，分析了系统的纵向动态特性，从而实现了对起动、制动等过程的控制和优化。     

Investigation of in-train stability and safety assessment for railway vehicles during braking

In-train stability of railway vehicles has becoming a major concern for railway vehicles, which refers to the jackknifing behavior of couplers under large in-train forces. For the train to train rescue scenario, braking induced impacts from couplers can adversely affect the dynamic performance of the coupled train. It is indicated from field tests that in-train forces if combined with large rotational angles of couplers can produce vertical components, which will further lead to the interference of adjacent carbodies and structural damages. In this paper, the dynamic model of the train and coupler system is developed. The model verifications are conducted by comparing the calculated responses with the tested results. The safety indices are formulated on the basis of which the running safety of the coupled train is evaluated. The propelling test in the laboratory is conducted to reproduce the coupler jackknifing behavior. The quasi-static analysis and anti-jackknifing mechanism under compressing in-train forces are analysed. Parametric studies are then conducted to propose some limitations for the application of train to train rescue. It is indicated from numerical and testing results that the decrease of the braking deceleration or a limitation of the free rotational angle of couplers is beneficial to lower the amplitude of braking induced impacts.     

基于模糊动态故障树的动车制动系统可靠性分析

针对动车制动系统实际工作环境中的故障发生率具有模糊不确定性以及故障的发生具有动态性的特点,把模糊数学和马尔可夫（Markov）模型与故障树模型相结合提出一种基于模糊Markov模型的动态故障树分析方法,通过三角模糊数和扩展原理来表示底事件故障率和Markov模型中不同状态转移率的模糊性。利用动态故障树模型分析获得了系统故障树顶事件模糊故障率的隶属函数。解决了不确定条件下的动态系统可靠性分析问题,对兰新高速铁路上运行的动车组的制动系统进行分析,获得了制动系统可靠度预测曲线,为该路线上运行的动车的制动系统针对故障特点制定相应的检修和维护方案提供了理论依据。     

Dynamic simulation and analysis of the elevating mechanism of a forklift based on a power bond graph

An electric elevating mechanism is designed based on the working principle of the lifting equipment for the CPD30 forklift. The mathematical models based on the power bond graph for an electric elevating system and a hydraulic elevating system are built by considering the execution condition of the fork arms of a forklift, including starting, rising and braking. On the basis of these models, dynamic simulation and analysis are performed for the starting, rising and braking of the fork arms frame. Then, the corresponding mathematical model is derived. Furthermore, the curve of the movement velocity of the fork arms frame is determined. The characteristics of the two types of lifting mechanism are summarized for two types of working effect of the lifting system under the same conditions by comparing the difference between the actual trajectory curve and the curve of the original plan. The theoretical foundations for the type selection of the forklift elevating mechanism and even that of engineering machinery are provided.     

大惯量有轨输送车的精确定位控制

针对大型窑炉有轨输送车惯性大、要求平稳起动和制动、定位精度要求高的特点,阐述了大惯量有轨输送车起动和制动的控制方法,并详细地叙述了有轨输送车有选择地精确定位的控制方法。实践表明,采用软起动和二次停车完全可满足大惯量有轨输送车的控制要求。     

计入运动副间隙的汽车制动摆振动态响应分析

建立了考虑制动过程中参数时变特性,并计入转向系运动副间隙耦合作用的七自由度非自治摆振系统的动力学模型。通过MATLAB数值算例,对制动过程中转向轮摆振的动态响应进行了分析。考察了轴荷转移、车速、间隙、轴距等因素对系统瞬态响应的影响。研究结果表明：制动过程中,轴荷转移等时变特性及运动副间隙的耦合作用对摆振系统动力学行为有重要影响,在建模时应予以考虑。相关规律与试验结果基本吻合,验证了模型的准确性。     

运枕龙门起重机控制系统设计与高性能行走制动策略研究

介绍了运枕龙门起重机控制系统的组成和工作模式。通过分析龙门起重机制动过程动力学模型提出了1种高性能的行走制动控制策略,具有制动距离短、防打滑、制动性能高等优点。