摆线齿轮泵内转子加工工艺及工装设计

摆线转子泵具有体积小、结构紧凑、零件少、重量轻、噪声低、工作平稳、自吸性强及良好的高转速特性等特点,广泛用于纺机、印机、机床、轻工机械等需低压连续润滑或间断供油润滑的机械设备上.分析了内转子齿廓为短幅外摆线圆内等距线,而不宜采用普通外摆线及长幅外摆线的原因,确定了磨削参数、机床的改装方法及专用工艺装备.     

三头单螺杆泵定转子接触磨损分析

采用ANSYS软件对短幅内摆线外等距曲线及短幅外摆线内等距曲线2种线型的三头单螺杆泵在过盈及压差作用下的变形、受力及接触情况进行有限元分析,得到定转子接触时变形及应力分布云图,比较2种线型三头单螺杆泵的密封性能.结果表明:过盈量的存在是实现螺杆泵密封的重要条件;压差的存在使定子橡胶发生较大的变形,应力应变值也相应增加;短幅内摆线外等距曲线三头单螺杆泵密封性能优于短幅外摆线内等距曲线三头单螺杆泵.     

短幅外摆线的等距线齿廓的生成、加工及测量

摆线转子泵、摆线液压马达、摆线式全液压转向器等三种液压元件,由于体积小、重量轻、结构简单、成本低、性能好,被广泛地应用于工程、建筑、农业、轻工等机械和机床行业。它们的主体机构是内啮合一齿差短幅外摆线针轮传动机构,由两个关键的基本件——定子和转子组成。转子短幅外摆线的等距线齿廓精度高低,直接影响到元件的机械效率、容积效率、压力损失、噪音和使用寿命等主要性能。所以对这个零件的质量,作了很多方面的研究和工艺试验。我厂生产的摆线液压马达和摆线式全液压     

新型内啮合齿轮油泵设计的参数选择与量柱测量距的计算

一、前言短幅外摆线内啮合齿轮油泵是一种体积小、流量大、脉动小、噪音低、寿命长、结构简单的定轴轮系的新型内啮合齿轮油泵。目前已被应用到机械、化工,纺织,石油等行业中低压的润滑、输送、液压系统中。其构造见图1。     

高性能摆线油马达

随着工业的发展,世界各国都在研制适用于车辆、机床以及各种机械所需要的小型低速大扭矩油马达。摆线油马达就是其中之一。它的结构是内啮合短幅外摆线齿轮式,并采用一齿差行星减速器的原理,故具有高速液压马达和机械减速机相组合的低速大扭矩装置的特点。而且还具有结构简单、紧凑、体积小,重量轻、输出扭矩大、起动及低速稳定性好和使用方便等优点,所以发展较快。     

RV传动啮合齿形参数化设计及其软件开发

RV(Rotate Vector)减速器是工业机器人的关键元器件之一,啮合齿形设计是RV传动设计的重要环节。根据RV传动基本几何参数之间的关系及短幅摆线与长幅外摆线的不同齿廓特点,提出相应的参数化设计方法;以Auto CAD软件为平台,采用Auto Lisp语言开发了正/负一齿差、正二齿差、正三齿差等典型少齿差短幅摆线针轮传动及长幅外摆线针轮传动的参数化设计软件,提高了设计效率。     

短幅外摆线齿轮的公法线测量

近二十年来我国已有许多工厂生产摆线针轮行星减速器,其摆线轮是用摆线磨床磨削成形的,一般是用顶根距测量法控制其制造精度;但这样的测量方法不能正确反映短幅外摆线的齿形;例如,机床径向进给量的调整、砂轮圆弧半径等方面是否满足设计要求,用上述的方法是不能判断出来的,因此本文提出简便的公法线测量法。     

计算机辅助求解长幅外摆线针齿传动的啮合参数

根据干涉原则.将求解长幅外摆线齿轮极限齿顶圆半径的问题转化为有约束优化问题.提出了相应的目标函数和约束.同时,应用计算机求解最小齿厚等参数.在此基础上,得到长幅外摆线针齿传动的全部啮合参数.     

短幅外摆线滚子链轮齿廓方程研究

根据短幅外摆线的形成机理,推导出一种新型滚子链轮。为了获得短幅外摆线链轮的性能,建立了短幅外摆线链轮的正时链传动模型,并进行了仿真分析。结果表明,采用短幅外摆线齿廓的凸轮轴链轮的角速度不均匀系数比GB1244-85标准链轮的降低了25.2%,比DIN8196标准链轮的降低了3.6%,短幅外摆线链轮能有效降低链轮的角速度波动,提高系统传动的平稳性。     

加工摆线齿轮的宏程序

本文论述在加工中心上加工摆线齿轮及其编程特点，并给出了可用机床基本功能G02／G03，而无须借助机床选配功能来加工摆线齿轮的宏程序。程序调用简单，摆线齿轮更改参数时只要改变赋值即可。一、摆线齿轮的参数方程摆线齿轮齿形为短帽等距外摆线，其方程为：W、Z——内、外转子齿数R——分度圆半径U——齿形圆直径E——内、外转子偏心距由于摆线齿轮几何形状复杂，技术要求高，在加工中心上采用圆弧插补法编程加工，经粗加工后余量可做到小而均匀，加工后的几何误差和齿形误差都小，最后用硬质合金铣刀高切削速度低进给量精铣到位，既能…     

A study of friction in worn misaligned journal bearings under severe hydrodynamic lubrication

Friction occurs in all mechanical systems such as transmissions, valves, piston rings, bearings, machines, etc. It is well known that in journal bearings, friction occurs in all lubrication regimes. However, shaft misalignment in rotating systems is one of the most common causes of wear. In this work, the bearing is assumed to operate in the hydrodynamic region, at high eccentricities, wear depths, and angular misalignment. As a result, the minimum film thickness is 5–10 times the surface finish, i.e., near the lower limit of the hydrodynamic lubrication when taking into account that in the latest technology CNC machines the bearing surface finish could be less than 1–2 μm.An analytical model is developed in order to find the relationship among the friction force, the misalignment angles, and wear depth. The Reynolds equation is solved numerically; the friction force is calculated in the equilibrium position. The friction coefficient is presented versus the misalignment angles and wear depths for different Sommerfeld numbers, thus creating friction functions dependent on misalignment and wear of the bearing. The variation in power loss of the rotor bearing system is also investigated and presented as a function of wear depth and misalignment angles.     

Smart lubrication via pump response interval (PRI) variation in the machining process

The development of new lubrication methods in CNC machine carriages is a current requirement in the machining industry. Previously, lubrication systems of CNC machines were only improved via injection automation approaches. This paper focuses on the lubrication mode on the linear guideways of CNC machines. Additionally, the research investigates the effects of oil injection time and the amount of the required lubricant for accurate and precise machining. This study was also concerned with variations in environmental temperature and carriage movement conditions. Oil injection amount was determined by pump response interval (PRI), which was varied for optimization. Smart optimum quantity lubrication (SOQL) was applied to overcome unexpected changes in practical parameters during machining. The optimum oil consumption of SOQL was achieved when PRI was 15 s, resulting in a reduction of oil consumption of up to 25 %. The SOQL technique is an emerging method in lubrication technology and plays an important role in alleviating the current issues that CNC lubrication systems are faced with.     

超声波电机驱动接触面的润滑和效率

为了提高复合振动体型超声波电机的效率，利用润滑剂在动压下混合润滑的特点，试制了与润滑摩擦驱动相适应的新型转子和定子．检测和分析了油膜的形成，转子、定子间的相对变位和扭转振动速度的关系以及电气-机械变换效率、转速、扭矩等。实验结果表明，干磨擦驱动时的电机效率为40％左右，注润滑油润滑驱动时，电机效率可以达到70％。     

Vibratory behaviors of Jeffcott system on cylindrical roller bearings

A Jeffcott rotor system on cylindrical roller bearings is studied in detail. Its critical speed is calculated by a new calculation method with roller bearing stiffness and damping. The influences of bearing parameters, such as the roller length, rotor mass, distance between the bearings and the kinematics viscosity of lubrication on the system critical speed are numerically studied, and the influences of an oil film and damping on the critical speed are also studied. Regular curves of the relationship between the geometric parameters and the system critical speed are obtained. The results show that with increasing roller length and radial load, the critical speed increases; and with increasing rotor mass and the distance between the bearings and the kinematics viscosity, the critical speed decreases. This means that an oil film will decrease the critical rotational speed of the rotor system.     

Detection of combined faults in induction machines with stator parallel branches through the DWT of the startup current

The main objective of this paper is to diagnose the presence of combined faults in induction machines. For this purpose, a methodology based on the application of the Discrete Wavelet Transform (DWT) to the stator startup current is used. This approach was applied in previous works with success to the diagnosis of rotor asymmetries and mixed eccentricities in motors with different sizes and conditions. However, as most of the diagnosis methods hitherto developed, the application of the proposed approach was circumscribed to situations in which a single fault was present in the machine. In addition, the influence of other phenomena such as load torque oscillations or voltage fluctuations was studied, but without considering the combination of these phenomena and the fault in the machine. This work is intended, first, to apply the proposed transient-based methodology to several cases in which different faults (rotor asymmetries, mixed eccentricities and inter-turn and inter-coil stator short-circuits) are simultaneously present in the machine and, second, to apply it to cases regarding faults combined with other phenomena making difficult the diagnosis, such as load torque oscillations. Interesting considerations regarding the preponderance of the effects of some of the faults are also done in the paper. The application of the methodology is focused on induction machines with stator parallel branches; in this sense, the suitability of the use either of the phase current or of the branch current for the diagnosis of each particular fault is analysed. The results look promising with regard to the validity of the methodology for the reliable discrimination of simultaneous electromechanical faults and the diagnosis of faults combined with other phenomena.     

A Transient Mixed Lubrication Model of a Rotary Lip Seal with a Rough Shaft

A rotary lip seal, widely used in machines containing rotating shafts, is usually protected from mechanical and thermal damage by a thin film of lubricant under the lip, separating the lip and the shaft surfaces. However, under some transient conditions such as those during startup and shutdown, the fluid film is not fully established or it breaks down, and the seal operates in the mixed lubrication regime. To simulate such cases, a transient mixed lubrication analysis has been developed. It generates predictions of such seal operating characteristics as load support sharing between hydrodynamic and contact pressure, contact and cavitation area ratio, the reverse pumping rate, and the average film thickness. In most previous numerical simulations of the rotary lip seal, the shaft surface is modeled as perfectly smooth. In the present study, a more realistic shaft surface with asperities is used, and the effect of the shaft surface roughness on the behavior of the seal is investigated.     

Measurements of Squeeze-Film Bearing Forces and Pressures,Including the Effect of Fluid Inertia

Squeeze-film dampers are commonly applied to high-speed rotating machinery, such as aircraft engines, to reduce vibration problems. The Reynolds theory of hydrodynamic lubrication has been used for the design and modeling of dampers in rotor dynamic systems despite typical modified Reynolds numbers in applications between ten and fifty. Lubrication theory is strictly valid for Reynolds numbers much less than one, which means that fluid viscous forces are much greater than inertia forces. Theoretical papers which account for fluid inertia in squeeze films have predicted large discrepancies from lubrication theory, but these results have not found wide acceptance by workers in the field. Recently, experimental results on the behavior of rotor dynamic systems have been reported which strongly support the existence of large fluid inertia forces. In the present paper, direct measurements of damper forces and pressures are presented for tile first time at high Reynolds number. Reynolds numbers up to 13 are obtained at eccentricity ratios 0.2, 0.5, and 0.8. Lubrication theory underpredicts the measured forces by up to a factor of two (100 percent error). Qualitative agreement is found with predictions of improved theories which include fluid inertia forces.     

Estimation of frequency components in stator current for the detection of broken rotor bars in induction machines

The limitation of data window length in induction machine broken rotor bar diagnostics is a real challenge in practice. Sideband frequencies which are used as broken rotor bar indicators are very close to the fundamental frequency and have low magnitude. Traditional spectral analysis approach such as Discrete Fourier Transform (DFT) can be inaccurate in these conditions due to its inherent drawbacks such as the requirement of long data window for high resolution and the side lobe leakage in frequency domain. In this paper, a high-resolution spectral analysis technique, Prony Analysis (PA), is proposed for broken rotor bar detection in induction machines. The method is described and demonstrated in detail, validated by experimental data, and compared with DFT. Results clearly indicate the advantages of PA over DFT in terms of maintaining a high resolution with a much shorter window and a better frequency estimate accuracy with the same window length.     

Influence of Rotor Eccentricity in Ultrahigh-Speed Electrical Machines on Their Characteristics

The influence of rotor eccentricity in high-speed and ultrahigh-speed electrical machines on their characteristics is considered. A mathematical model permits analysis of the processes in ultrahigh-speed electrical machines with an eccentric rotor. The model is verified by computer simulation and also by means of physical experiments.     

Single line metered oil lubrication systems

Although the majority of machine tools on the market are now equipped with some form of centralised lubrication system, there are still a great many small machines being sold without any effective system of lubrication. This is surprising since in many cases the fitting of such a system would add no more than 1% to the price of the machine. The latest developments in single line metered oil lubrication systems give both the manufacturer and user greater reliability, accuracy and flexibility. Considerable progress is being made towards even greater system reliability while future trends point towards even more simplicity combined with increased interest in safety devices to prevent pump and system failures.