工件非整圆部分内径的快速测量

在机械制造行业中,测量零件的内径,并判断圆周上各个方向的直径值是否都在公差范围内,是经常遇到的事。但若零件的被检部分并非整圆,仅为半圆或一段圆弧,问题就较为复杂。尤其是在大批量生产的情况下,找出合适的测量方法并研制相应的检测装置往往显得更重要。图１所示的轴承盖中,有二个大小不等的半圆孔Ｒ１和Ｒ２,我们面对的问题就是要测量这二个孔在半圆范围内的内径变动量。图１　轴承盖　　由于这项参数是零件经高效专用机床成批加工后,在工序间进行检验的,因此,不可能采用计量室里那些测量方法,而得找到一种既有足够的测量…     

缸中活塞运动位移和速度的测量装置

众所周知,用系统来测量各种装置的运动部件线性位移和速度,在速度达数m/s,和加速度达数十m/s~2的复杂运动动态情况下,采用较少。它不可能在大的加速度情况下工作,也不可能保证必须的测量精度。下面介绍的装置,用来研究当使用一般的测量和记录仪器时,压气缸在完成快速运动过程中,活塞运动的动态特性.装置的原理示意图如图1所示.     

振动样品磁强计低温测量装置的研制

本文介绍了为美国ＰＡＰ公司产品振动样品磁强计（ＶＳＭ）配套的简易液氮低温测量装置的构造和制作方法。并对原样品盒作了改进。     

一种电梯平衡系数测量装置的研制

在当前测量电梯平衡系数的实际工作中,存在劳动强度大、测量方法复杂、工作效率低的缺点.文中介绍了一种新型电梯平衡系数测量装置的原理、设计和测量方法,具有便于携带、安装方便、操作简单、劳动强度低、工作效率高、测量结果准确的优点,适用于绝大多数电梯的平衡系数的测量.     

超精圆度仪全自动误差分离装置的研制

介绍作者研制的用于提高圆度仪测量精度的全自动误差分离装置。该装置不仅可以使圆度仪主轴回转误差从被测工件测量结果中可靠分离 ,而且整个测量过程实现了全自动无人操作 ,提高了系统的抗干扰能力及可靠性     

手拉葫芦性能参数测量装置的研制

手拉葫芦性能参数测量装置的研制机械部北京起重运输机械研究所郑时声顾原袁方定手拉葫芦是一种量大面广的手动起重设备。当手拉葫芦提升额定载荷时，在手拉链上要施加一定的手拉力，其力的大小将显示该手拉葫芦的整机效率。我们研制的测量装置就是专门用来测量手拉葫芦的...     

预防柴油机拉缸与烧活塞的措施

（1）确保活塞与气缸有合理的配合间隙更换新活塞与气缸时,要保证合理的配合间隙。确定此间隙有3种方法。①计算法。计算法仅从温度引起的热膨胀考虑,只是从理论上进行研究,实际应用还存在一定的问题,所以这种方法没有得到广泛的应用。     

特大型推力球保持架中心径测量装置的改进

通过对特大型推力球保持架中心径测量装置的改进,能精确测量保持架中心径,保证装配旋转精度。     

Analysis of oil consumption in cylinder of diesel engine for optimization of piston rings

The performance and particulate emission of a diesel engine are affected by the consumption of lubricating oil.Most studies on oil consumption mechanism of the cylinder have been done by using the experimental method,however they are very costly.Therefore,it is very necessary to study oil consumption mechanism of the cylinder and obtain the accurate results by the calculation method.Firstly,four main modes of lubricating oil consumption in cylinder are analyzed and then the oil consumption rate under common working conditions are calculated for the four modes based on an engine.Then,the factors that affect the lubricating oil consumption such as working conditions,the second ring closed gap,the elastic force of the piston rings are also investigated for the four modes.The calculation results show that most of the lubricating oil is consumed by evaporation on the liner surface.Besides,there are three other findings:(1) The oil evaporation from the liner is determined by the working condition of an engine;(2) The increase of the ring closed gap reduces the oil blow through the top ring end gap but increases blow-by;(3) With the increase of the elastic force of the ring,both the left oil film thickness and the oil throw-off at the top ring decrease.The oil scraping of the piston top edge is consequently reduced while the friction loss between the rings and the liner increases.A neural network prediction model of the lubricating oil consumption in cylinder is established based on the BP neural network theory,and then the model is trained and validated.The main piston rings parameters which affect the oil consumption are optimized by using the BP neural network prediction model and the prediction accuracy of this BP neural network is within 8%,which is acceptable for normal engineering applications.The oil consumption is also measured experimentally.The relative errors of the calculated and experimental values are less than 10%,verifying the validity of the simulation results.Applying the established simulation model and the validated BP network model is able to generate numerical results with sufficient accuracy,which significantly reduces experimental work and provides guidance for the optimal design of the piston rings diesel engines.     

液压缸拆卸设备的开发与设计

液压缸作为液压系统的执行元件,属于故障多发部位。维修液压缸时通常需要将其拆卸解体,为降低检修劳动强度、提高生产效率,设计开发出了一套新型的液压缸拆卸设备,由工作缸和待拆卸缸组成,工作缸的快速伸出、慢速伸出、慢速退回由液压系统控制实现,并介绍了电气控制系统设计原理。经实践检验,该液压缸拆卸设备结构合理、制作简单、成本低,能够满足生产实际需要,且性能优良。     

斜盘式柱塞泵柱塞-缸体摩擦副的润滑计算与分析

通过对柱塞-缸体间的油膜厚度进行理论计算与分析,进一步分析柱塞-缸体间的倾角、供给压力、柱塞自转及偏心距等相关因素对油膜压力分布的影响,并从润滑角度提出改善其润滑状态、减少磨损和延长使用寿命的建议.     

Tribological evaluation of piston skirt/cylinder liner contact interfaces under boundary lubrication conditions

The friction and wear between the piston and cylinder liner significantly affects the performance of internal combustion engines. In this paper, segments from a commercial piston/cylinder system were tribologically tested using reciprocating motion. The tribological contact consisted of aluminium alloy piston segments, either uncoated, coated with a graphite/resin coating, or an amorphous hydrogenated carbon (a‐C : H) coating, in contact with gray cast iron liner segments. Tests were conducted in commercial synthetic motor oils and base stocks at temperatures up to 120°C with a 2 cm stroke length at reciprocating speeds up to 0.15 m s⁻¹. The friction dependence of these piston skirt and cylinder liner materials was studied as a function of load, sliding speed and temperature. Specifically, an increase in the sliding speed led to a decrease in the friction coefficient below approximately 70°C, while above this temperature, an increase in sliding speed led to an increase in the friction coefficient. The presence of a coating played an important role. It was found that the graphite/resin coating wore quickly, preventing the formation of a beneficial tribochemical film, while the a‐C : H coating exhibited a low friction coefficient and provided significant improvement over the uncoated samples. The effect of additives in the oils was also studied. The tribological behaviour of the interface was explained based on viscosity effects and subsequent changes in the lubrication regime, formation of chemical and tribochemical films. Copyright © 2010 John Wiley & Sons, Ltd.     

Scuffing failure analysis and experimental simulation of piston ring–cylinder liner

The scuffing failure phenomenon of piston ring–cylinder liner is studied theoretically and experimentally. The load and bulk temperature when scuffing failure occurs are measured under different engine speed, lubricant, and environmental temperature in a bench test. Based on the experimental results, the asperity capacity when scuffing occurs is evaluated. Surface contact temperature is determined with the measured bulk temperature and the surface flash temperature calculated by Blok theory. The scuffing failure threshold of piston ring–cylinder liner is established by using specific oil film thickness. This revised version was published online in June 2006 with corrections to the Cover Date.     

Investigation on the radial micro-motion about piston of axial piston pump

The limit working parameters and service life of axial piston pump are determined by the carrying ability and lubrication characteristic of its key friction pairs. Therefore, the design and optimization of the key friction pairs are always a key and difficult problem in the research on axial piston pump. In the traditional research on piston/cylinder pair, the assembly relationship of piston and cylinder bore is simplified into ideal cylindrical pair, which can not be used to analyze the influences of radial micro-motion of piston on the distribution characteristics of oil-film thickness and pressure in details. In this paper, based on the lubrication theory of the oil film, a numerical simulation model is built, taking the influences of roughness, elastic deformation of piston and pressure-viscosity effect into consideration. With the simulation model, the dynamic characteristics of the radial micro-motion and pressure distribution are analyzed, and the relationships between radial micro-motion and carrying ability, lubrication condition, and abrasion are discussed. Furthermore, a model pump for pressure distribution measurement of oil film between piston and cylinder bore is designed. The comparison of simulation and experimental results of pressure distribution shows that the simulation model has high accuracy. The experiment and simulation results demonstrate that the pressure distribution has peak values that are much higher than the boundary pressure in the piston chamber due to the radial micro-motion, and the abrasion of piston takes place mainly on the hand close to piston ball. In addition, improvement of manufacturing roundness and straightness of piston and cylinder bore is helpful to improve the carrying ability of piston/cylinder pair. The proposed research provides references for designing piston/cylinder pair, and helps to prolong the service life of axial piston pump.     

Design approach for single piston hydraulic free piston diesel engines

The operating characteristics of a single piston hydraulic free piston diesel engine differ significantly from conventional diesel engines and this provides a theoretical basis for controlling and optimizing the design of the engine. The design of the proposed engine intended as a power supply for a hydraulic propulsion vehicle is presented. An engine performance forecast model was generated in AMESim. The performance of the prototype engine is predicted and the predictive results are verified with experiments. The particular features of the engine are discussed. The dynamic characteristics of the prototype engine are analyzed and the results indicate the rationality and feasibility of the engine design parameters. The features of the controllable working frequency and the intermittence output flows are provided. The flow capacity characteristics of the hydraulic valves on the prototype engine are offered. The methods for starting and the operation after misfire are presented.     

Research on unsteady flow measurement standard device based on active piston

In this paper, an unsteady flow measurement standard device is studied and designed. The device can be used to measure the flow rate of any liquid medium. First, through comparative analysis of the design scheme of the unsteady flow measurement standard device, the structure of the active piston type is determined, and the schematic diagram is designed. According to the schematic diagram, the mathematical model of the device based on the active piston is established, and the uncertainty of the device is evaluated. Second, the hardware control system is designed and built according to the uncertainty evaluation results. Then, the upper computer operating system of the device is constructed, and a highly integrated human-computer interaction data acquisition and control system is established. Finally, the measurement performance of the device is verified by comparing the set value with the measured value of flow rate, and the uncertainty of the device is analyzed. The combined standard uncertainty can meet the expected value of 0.5%.     

电液锤活塞密封窜漏的原因分析及改进

电液锤液气缸活塞密封采用由PTFE制造的格莱圈密封,在使用中液压油会窜入气腔,导致气体压力升高。本文分析了由于缸体膨胀、密封失效而发生窜漏的两种原因,即液膜流过密封环时在气腔积聚和收锤造成的压力冲击。并提出了在格莱圈后安装Yx圈的改进措施。     

发动机缸套轴颈部滚压装置及其控制系统的设计

对发动机缸套轴颈部进行滚压加工的意义和要求进行了探讨,设计了一套滚压结构与控制系统。通过机械结构与液压伺服系统实现对滚压工艺过程及滚压力、滚压圈数、滚压速度等滚压参数的精确控制,解决了缸套轴颈部滚压实施过程中没有合适监控方法的问题,对发动机缸套的实际生产具有重要意义。