Influence of Friction Drive Lift Gears Construction on the Length of Braking Distance

The friction drive elevators the influence of the braking distance has very high significance to meet certain safety regulations and comfort.During the emergency braking the delay for the system a frame and a cabin should be within the range from 0.2 to 9.81 m/s~2.However,there are no specialist literatures regarding the issues connected with emergency braking of elevating devices either.The results of the own empirical research work are presented regarding the influence of design changes on the working parameters of the friction drive elevator gears.ASG100,KB 160,PP16,PR2000UD and CHP2000 types of safety progressive gears are analyzed.ASG100,KB 160,PP16,PR2000UD type progressive gears are already produced by European manufacturers.CHP2000 type gears are established as the alternative option for the already existing solutions.The unique cam system has been used in the CHP 2000 gears.The cam leverage gives the chance to unblock,in a very easy way,the clamed gears after braking.Thus,it is a key aspect to perform laboratory tests over the braking process of a newly created solution.The proper value of the braking distance has a significant influence on the value of delay in terms of binding standards.The influence of loading on the effective braking distance and the value of the falling elevator cabin speed are analyzed and the results are presented.The results presented are interesting from lift devices operation and a new model of CHP 2000progressive gear point of view.

Study on deformation and microstructure characterizations of mild steel joints by continuous drive friction welding

Macro-deformation characteristics of continuous drive friction welded mild steel joints were examined by using one deformable workpiece （objective） and the other undeformable one （rigid）. The microstructure evolution and hardness change across the joint were studied. The results show that the axial shortening and radial increment of joints increase with increasing the frictiou time at l 200 rpm. The cementite particles of pearlites in the weld center are uniformly distributed on the ferrite matrix, while the cementites of the pearlite in the thermal-mechanically affected zone are broken and discontinuously dispersed in the pearlite. The hardness decreases rapidly from the weld center to the parent metal under the coupled effects of heat and deformation during the rapid heating and cooling processes.

Evolution of microstructural and mechanical properties of AISI 316 during continuous drive friction welding process

The aim of present study is introducing a method by subdividing friction welding phases into three steps according to the temperature change during continuous drive friction welding operation. Thermal curve allowable subdividing of the friction welding phase's time into three distinct periods, while the microstructure evolution during friction welding goes through three different situations. The effects of three distinct periods were achieved by macro-microscopy, microhardness HV_(0.1), tensile tests and scanning electronic microscopy(SEM).The results clearly show that the microstructure during the friction phase goes through three completely different situations which mechanically influenced on microstructure, tensile strength and ductility of the welded joint.

NUMERICAL SIMULATION OF FLOW FIELD BETWEEN FRICTIONAL PAIRS IN HYDROVISCOUS DRIVE SURFACE

The flow field of the oil film between frictional pairs in the hydroviscous drive test rig is investigated. A three-dimensional Navier-Stokes（N-S） equation considering viscous force and inertial force rather than Reynolds equation or modified Reynolds equation is presented to model the flow field. Pressure and temperature distribution in radial and circumferential direction under three different conditions, i.e., isothermal, that considering viscosity-temperature characteristic as well as shear thinning non-Newtonian fluid are simulated, respectively, by utilizing the commercial computational fluid dynamics（CFD） software FLUENT. The results reveal that the grooves on the driven plate make the pressure, temperature distribution present periodic variation. The oil temperature and shear rate have important effects on the flow field between frictional pairs, and the oil temperature is more important parameter. The simulation results lay a theoretical foundation for the reasonable designs ofhydroviscous drive.

Effect of temperature field on flashes formation of continuous drive friction welding

On basis of the finite element software DEFORM, the 2D coupled thermo-mechanical model of continuous drive friction welding of ring parts is established. The temperature and the flashes during the welding process are investigated. The results of numerical simulation show that the temperature of friction surface is higher than that of other region and the peak temperature increases with the increase of welding time. During the process of friction stage, no flash appears because of the low temperature and the small axial friction pressure. At the forging stage, the flashes appear, whose dimensions and bending degree increase with the increase of welding temperature. Moreover, with the increase of rotational velocity and axial forging pressure, the dimensions and the bending degree of flashes of continuous drive friction welding increase.

Theoretical Model and Experimental Research on Friction and Torque Characteristics of Hydro-viscous Drive in Mixed Friction Stage

The hydro-viscous drive(HVD)has been widely used in fan transmission in vehicles,fans,and scraper conveyors for step-less speed regulation or soft starting.In the mixed friction stage,the contact,friction,and torque characteristics of friction pairs are very complex and change at any time.The characteristics of the frictional and hydrodynamic lubrication states were studied in order to calculate and predict the friction and torque characteristics of the friction pairs in the mixed friction stage.The fluid torque was calculated by applying the average shear stress model and the load-carrying capacity of asperity was determined on the basis of the fractal contact theory.In addition,the contact friction coefficient of the friction pairs was taken into consideration and measured by using the MM1000-Ⅲfriction and wear testing machine.The asperity friction torque and total torque in the mixed friction stage were obtained and finally,the test rig for the torque characteristics was set up.The results show that the contribution to the total torque is shared by the oil film and the asperity friction.The friction coefficient decreases sharply at first and then increases with a change in the relative rotational speed,following the Stribeck curve closely,and the contact frictional coefficient slowly decreases with increase in the pressure between the friction pairs.The torque between the friction pairs is provided by the asperity friction,and the torque due to the oil film reduces to zero.When the thickness of the oil film is small,a major contribution to the total torque is due to the asperity friction.The total torque also increases with the decrease in the film thickness ratio.Therefore,by theoretical analysis and experimental verification,the torque of the friction pairs in the mixed friction stage can be accurately calculated using the average shear stress model and asperity friction torque model.

Impulse Controller Design of a Harmonic Drive System with Friction

A friction model was established for impulse control design in a precision control system. First, the physical characteristics of the impulse in momentum, such as motion and energy, were analyzed and formulated. Then, experimental response to a new pulse with two harmonic expansions was studied. The first harmonic is the main pulse to drive the arm, and the second harmonic has two functions： its first half helps the main pulse eliminate the dead zone, and its second half, a negative pulse, stops the arm motion quickly. Finally, an impulse feedback controller was developed. Comparison between simulation and experiments shows the effectiveness of the proposed controller.

摆线针轮减速机参数对传动效率的影响与参数优化

为进一步提高摆线针轮减速机的传动效率,对减速机传动效率的影响规律进行了深入研究,提出了考虑设计参数与工况参数变化的摆线针轮减速机传动效率计算模型,并对参数进行了优化。首先,考虑摩擦力和啮合齿隙,建立了摆线针轮传动机构的多齿承载接触分析模型,计算了摆线针齿啮合力与载荷分布规律;然后,考虑摆线针轮减速机的啮合损耗、输出损耗、轴承损耗、润滑损耗和密封损耗,提出了摆线针轮减速机传动效率计算模型,并分析了设计参数和工况参数对摆线针轮减速机传动效率的影响规律。研究表明,在考虑摩擦受力的情况下,转速、负载、针齿销半径、针齿分布圆半径、偏心距、针齿套半径是影响传动效率的主要参数,针齿销数、柱销分布圆半径、柱销半径和摆线轮齿宽次之。最后,以齿轮强度、齿轮宽度、齿廓形状、齿间间隙和承载能力作为参数优化范围,将效率和体积作为目标对设计参数进行多目标优化分析,得到最优参数解,进而获得了更小体积、更高传动效率的摆线针轮减速机。

热循环下铝/钢连续驱动摩擦焊接接头应力应变分析

利用ABAQUS有限元软件,建立了一个新的连续驱动摩擦焊接头热-力耦合过程的数值模型,分析了试验过程接头温度场、应力应变分布规律,通过与实际试验结果的对比,验证模型的准确性。得出如下结论:热循环过程中,冷却及低温保温过程是热应力最大的阶段;接头颈缩形貌和产生位置与试验结果吻合较好,颈缩位置与实际试验相对误差为6%,颈缩现象的本质是铝在自由膨胀收缩时应力超过强度极限产生的塑性变形。在拉伸断口观察到解理断裂圆环,其位置、宽度与模拟结果的应变集中区域吻合度高。该模型较准确的模拟了连续驱动摩擦焊接头的热-力耦合过程,为实际生产和工艺优化提供了有力支持。

齿轮啮合周期内摩擦载荷变化有限元仿真分析

为能更好地分析齿轮啮合周期中摩擦载荷变化,建立齿轮分析模型,研究齿轮间传动关系,区分齿轮输入端和输出端的阻力扭矩,搭建有限元分析模型。为保证模型的精确度,在前期预处理阶段针对齿轮不同位置的实际情况构建对应网格,区分不同位置的网格密度,根据齿轮的轮动比和角位移得出旋转自由度。在齿轮啮合过程中,搭建动力学分析模型,研究摩擦载荷的变化情况,考虑齿轮啮合频率,根据长度线条确定摩擦因数,利用摩擦函数明确齿轮间的最大接触应力和弯曲应力,完成摩擦载荷变化分析。经仿真验证可知,所研究方法能准确描述齿轮啮合周期内摩擦载荷的实时变化。

一种丝鞘机构的长距离摩擦损失分析

针对丝鞘机构中严重的非线性摩擦力损失与非线性弹性伸长,提出了一种考虑速度影响的丝鞘机构新型摩擦模型,并进行了摩擦参数辨识工作。此外,对不同驱动速度下的摩擦模型进行了仿真分析。结果表明,所提出的摩擦与伸长模型可以补偿长距离丝鞘传动带来的传动损失,提高连续体操作臂的运动准确性。

煤矿长距离带式输送机线摩擦驱动增压装置设计与应用

针对线摩擦带式输送机运行过程中,空载、少载时承载带与传动带间摩擦产生的驱动力不足,导致主机系统能耗增加,以及满载时承载带与传动带间摩擦力激增造成的皮带过度磨损问题,设计了带式输送机线摩擦驱动增压装置,并通过模拟软件对其进行仿真分析.结果表明,摩擦驱动增压装置可按照预先设定的压力大小,自动调节皮带的法向力,能够改善驱动力不足的现象,有利于输送机长距离、大运量运输.同时为类似工况下线摩擦带式输送机的大规模投产使用提供借鉴.

顶锻压力对异种金属连续驱动摩擦焊接头力学性能的影响研究

针对顶锻压力对异种金属焊接质量影响的问题,通过在双主轴连续驱动摩擦焊机两侧主轴设置传感器对其进行监测。采用金相显微镜(OM)、扫描电镜(SEM)对比分析焊缝的断口形貌;基于左右两侧接头焊缝及同一焊缝不同位置的显微硬度的分析结果,总结顶锻压力对异种金属管材连续驱动摩擦焊缝力学性能影响规律,为连续驱动摩擦焊在生产中使用提供理论基础。

汽车电动尾门系统及电动撑杆的设计研究

研究了电动尾门系统的结构组成、系统功能及电动尾门的应用技术方案。并且针对电动尾门系统的核心部件执行机构——电动撑杆进行了进一步的设计与研究,详细介绍了电动撑杆的内部结构及外部布置环境校核,提供了电动撑杆的动态输出力值、尾门手动开闭操作力值、电动撑杆内部系统摩擦阻力及机械弹簧力值的设计计算方法。

肩部康复外骨骼单关节摩擦建模及补偿方法研究

针对肩部康复外骨骼关节转动时摩擦力大、反向驱动困难的问题,搭建了一个单关节实验平台,用于模拟肩部单关节的运动。为了较好反映运动中的摩擦力,采用Stribeck摩擦模型对单关节摩擦力进行建模,并通过最小二乘法拟合模型的未知参数,此外结合位置差和电流差的正负号确定摩擦力的方向。实验结果表明,采用Stribeck摩擦模型对摩擦力进行建模后,反向驱动力矩均值至少减少了80%,从而有效解决了肩部康复外骨骼单关节中阻力大、反向驱动困难的问题。

Modeling and analysis of rigid multibody systems with driving constraints and frictional translation joints

An approach is proposed for modeling and anal- yses of rigid multibody systems with frictional translation joints and driving constraints. The geometric constraints of translational joints with small clearance are treated as bilat- eral constraints by neglecting the impact between sliders and guides. Firstly, the normal forces acting on sliders, the driv- ing constraint forces （or moments） and the constraint forces of smooth revolute joints are all described by complementary conditions. The frictional contacts are characterized by a set- valued force law of Coulomb＇s dry friction. Combined with the theory of the horizontal linear complementarity problem （HLCP）, an event-driven scheme is used to detect the transi- tions of the contact situation between sliders and guides, and the stick-slip transitions of sliders, respectively. And then, all constraint forces in the system can be computed easily. Secondly, the dynamic equations of multibody systems are written at the acceleration-force level by the Lagrange multiplier technique, and the Baumgarte stabilization method is used to reduce the constraint drift. Finally, a numerical example is given to show some non-smooth dynamical behaviors of the studied system. The obtained results validate the feasibility of algorithm and the effect of constraint stabilization.

助飞运载器螺旋传动失效的机理研究

助飞运载器的螺旋传动缺乏摩擦及温升对其传动的作用机制研究。建立这种螺旋传动机构的热机耦合模型,并利用真实参数模拟传动接触面的热、力学等特性,通过分析应力、温升数据及其与摩擦系数之间的规律,揭示该螺旋传动的失效机制。数值模拟结果表明,该螺旋传动在大载荷的高速摩擦作用下,其传动接触面的温度能快速升至454.3℃,其接触应力可达699.4 MPa,高温降低了接触面的材料强度,因此高速滑动的摩擦力将对接触面造成持续破坏,计算结果和故障现象一致,研究成果也对该传动技术的工程应用提供了理论基础。

交错轴摩擦轮传动及其应用

交错轴摩擦轮传动具有回转运动与直线运动的转换、直线运动位移任意调节和远程往复输送、驱动能力自适应、过载自保护、传动效率高、磨损小、寿命长、成本低、结构和制造工艺简单等特点,100多年来得到较快的发展和应用,被广泛应用于自动化、智能化、精密定位等装备上,然而,在机械工程领域的教材和手册中并未将其明确系统地列出,在分类体系中仅对平行轴和相交轴摩擦轮传动进行归类。鉴于此,本文介绍交错轴摩擦轮传动技术原理和特点,归纳总结交错轴摩擦轮传动基本原理和两种基本运动形式及4种基本结构形式,构建完整的摩擦轮传动分类体系;同时从传动基本原理的角度,综述交错轴摩擦轮机构在不同工程领域中的应用和研究进展;指出交错轴摩擦轮传动技术目前存在的难点及问题,并对其发展趋势进行展望。

基于专创融合的摩擦轮传动教学体系的构建

文章基于专创融合的理念,在总结摩擦轮传动,特别是在交错轴摩擦轮传动100多年发展的基础上,完善了摩擦轮传动的分类体系,结合创新思维方法系统地梳理了交错轴摩擦轮传动在工程上的应用及特点,并提出了可破除领域知识壁垒的交错轴摩擦轮传动规范命名,突破了传统的摩擦轮传动教学体系,为机械设计中摩擦轮传动知识体系系统传播和教学体系的完整设计提供了参考,也为交错轴摩擦轮传动知识的普及传播奠定了基础。

A New Motor of Stick Type with Coupled Mechanical Vibration of Bimorph Beam and Frictional Force

This paper proposes a new non-magnetic motor with a rotor rotated by using the resonance energy of a bimorph cantilever beam excited by electrostatic force. The use of flexible material enables conversion of translational vibration to rotary movement in one direction. Basic characteristics of a prototype motor with two bimorph cantilever beams, such as rotational speed, output torque, and efficiency were determined experimentally. Results show that a maximum rotational speed of 2800 rpm was obtained without a load torque. It is also observed that this motor produces the output torque of 98 μNm when the rotational speed was 980 rpm. The maximum efficiency was 24% when the input power was 0.065 W.