超高压管材液压成形控制系统的研制

介绍了管材液压成形工艺,根据液压成形原理,自主研制出具备高压发生器、阀门管路等配件的超高压液压系统,同时通过可编程控制器实现对电磁元件的控制,有效地解决了管材在液压成形过程中的端口密封、进给补料等关键问题,为管材液压成形的实验研究奠定了基础。     

牙轮钻头径向非对称扁平密封性能研究

为了提高HAR橡胶密封圈寿命,提出一种新的径向非对称扁平密封结构。相比传统对称截面扁平密封圈,径向非对称截面的密封接触面积更小,因而减小了内圈动密封面旋转产生的热量以及磨损。通过试验对比氢化丁腈橡胶(HNBR)与丁腈橡胶（NBR）的性能,选择出合适的橡胶密封圈材料;分别建立径向非对称扁平密封圈与传统对称截面扁平密封圈的有限元模型,对比2种结构的密封性能;在不同的环境压力和温度下对径向非对称扁平密封圈的密封性能进行评价,并在现场进行应用验证。仿真结果表明：径向非对称扁平密封圈接触应力更大,密封性能更优;同时,其Mises应力明显低于传统对称截面扁平密封圈,证明径向非对称扁平密封更适合长期稳定工作。现场应用结果同样验证：在高温高压工况下,径向非对称扁平密封圈密封性能可靠,具有较高的实用价值。     

同心注水管柱分层测压密封段设计与研究

设计一种用于同心注水管柱长期分层静压测试的密封段，该密封段为纯机械结构，利用重力冲击触发，依靠井下压力推动活塞压缩胶筒进行坐封，具有施工简单、长期工作稳定可靠的优点。根据该密封段的使用要求，对常用的桶形胶筒结构进行改进，在胶筒内侧增加金属衬环，以增强变形的稳定性和可控性。ABAQUS有限元仿真结果表明，改进后的胶筒与配水器内壁的密封系数和最大接触压力均提高了30%以上，初始密封性能有了很大提高，室内样机试验证明其双向密封压差最大可达20 MPa。将该密封段样机在井下进行了10天的长期测试，达到了预期功能，可用于生产实践     

An analysis of hydroforming of longitudinally curved boxes with regular polygonal cross-section

A new kinematically admissible velocity field is suggested for the upper-bound solution of hydroforming of longitudinally curved boxes with regular polygonal cross-section. In order to maintain the uniform wall thickness the back-up fluid pressure is controlled to vary with respect to the punch position during the hydroforming process. The pressure vs punch stroke curves for various process conditions are determined from theoretical analysis. The effects of punch shape, work-hardening exponent, drawing ratio and friction are then analysed and discussed. Experiments are carried out in a hydroforming press according to the computed pressure vs punch stroke curves. The hydroformed specimens have shown very little thickness variation within a 5% range. Thus, the validity of the assumption of uniform wall thickness has been confirmed. The flange deformation from the computation is found to be in good agreement with the experimental observation. When the computed reference curve of pressure vs punch stroke relation has been used, no defect, i.e. no necking or no wrinkling has been observed in the experimental specimens. It has been shown that the present method of analysis can be effectively used for the hydroforming process design of longitudinally curved boxes with regular polygonal cross-section.     

大尺寸O形丁腈橡胶圈动密封性能测试分析

为研究大尺寸O形橡胶密封圈端面动密封性能,研制适应于大尺寸O形橡胶圈的动密封性能测试平台,测试水介质条件下绝对压力在15～600 kPa范围内O形橡胶密封圈端面动密封性能.基于正交试验设计,研究不同介质压力、压缩量(0.75～1.25 mm)和转速(5～50 r/min)下内径600 mm(截面直径10 mm)的丁腈橡...     

基于流固耦合的橡胶O形圈密封泄漏计算方法*

提出一种基于流固耦合的橡胶O形圈静密封泄漏计算方法。对平行平板泄漏模型进行改进,使其适用于通道截面高度可变的泄漏率、介质压力计算;采用有限元仿真方法进行固体力学分析,求解宏观接触压力;采用Greenwood-Willamson模型进行接触力学分析,求解泄漏通道平均高度。基于数值方法研究介质压力、环境温度、表面形貌参数对橡胶O形圈密封性能的影响规律。结果表明,随着介质压力、环境温度、表面高度分布标准差的增大,体积泄漏率逐渐增大。上述数值方法以泄漏率作为表征密封性能的参数,能综合考虑橡胶材料、介质、工况等多种因素对O形圈密封性能的影响,对橡胶O形圈的寿命预测和失效分析更具指导意义。     

An analysis of hydroforming of regular polygonal boxes

A new kinematically admissible velocity field is suggested for the upper-bound solution of three-dimensional hydroforming of regular polygonal boxes. In order to maintain the uniform wall thickness a back-up fluid pressure is controlled to vary with respect to the punch position during the hydroforming process. Thus the pressure vs punch stroke curves for various process conditions are determined from theoretical analysis. The effects of the work-hardening exponent, drawing ratio and friction are then analyzed and discussed. Control of the hydroforming pressure with respect to the punch stroke is shown to be very important for proper design of the process.     

双向连通槽热流固耦合热变形研究

针对传统的螺旋槽型不能满足旋转设备反向运转的密封要求的问题,根据双向槽型机械密封结构特点,提出一种双向连通槽型,通过建立热流固耦合模型,确立传热边界条件,采用ANSYS Workbench对几何模型进行单向耦合计算,讨论密封环在转速、压力作用下热变形规律.结果表明:双向连通槽泄漏量整体比螺旋槽型泄漏量小,且双向连通槽由...     

水平井裸眼封隔器密封结构优化研究

针对水平井压缩式裸眼封隔器存在的密封性差、坐封力低、胶筒与井壁间存在间隙等问题,对其密封结构进行改进与优化,设计出一种凸球形隔环和凹球形胶筒组相结合的新型密封结构。运用 ABAQUS 软件模拟密封结构封隔器胶筒的坐封情况,获得胶筒组轴向接触压力的分布规律,并分析胶筒硬度和摩擦因数对接触压力的影响。结果表明：新型密封结构凸球形隔环在轴向压缩胶筒的同时也起径向压缩作用,提高了胶筒与井壁和中心管间的接触压力,增强了封隔器的密封性能;胶筒与井壁间的接触压力随着胶筒硬度和摩擦因数的增大而增大,但过大的摩擦因数会导致下胶筒接触压力明显减小,应选择硬度和摩擦因数合适的胶筒,从而保证封隔器的密封可靠性。     

Theoretical study of solid back-up rings for elastomeric seals in hydraulic actuators

The use of back-up rings to support elastomeric seals in high-pressure hydraulic systems is well established in the industry. However, little is known about the operation of such devices and how they affect or interfere in the sealing mechanism of the seals they accompany. This study is an attempt to model solid, soft back-up rings in terms of elastohydrodynamic lubrication and establish their exact role in a sealing system in terms of sealing performance (leakage). The model is applied on a typical case of a linear hydraulic actuator for a wide range of sealed pressures (1–35 MPa) and operating temperatures (−55 to +135 °C), and with one ring installed on the low-pressure side of the actuator. A system of a rubber seal and a properly selected and installed back-up ring is shown to be often significantly more efficient in terms of fluid leakage than the seal without the back-up ring. A study reveals the effect of various parameters of the ring (e.g. the elastic modulus and the surface roughness) on the sealing mechanism and shows the optimum selection to minimize leakage.     

硅橡胶与金属黏附效应的产生与影响分析

为探讨橡胶密封件与金属法兰之间的黏附效应产生的原因及黏附效应对密封的影响,根据硅橡胶密封结构的使用特点,设计硅橡胶密封圈与金属法兰在不同温度、不同时间下的黏附实验.通过硅橡胶密封圈与防锈铝合金和2种不锈钢材料的对比实验发现,硅橡胶密封圈与不锈钢金属法兰易发生黏附,与防锈铝合金金属法兰不易发生黏附.通过对金属法兰表面接触...     

旋转式唇型圈停车密封开启全过程密封特性研究

为探究旋转式密封圈脱开全过程的密封性能参数变化,借助非线性有限元软件ANSYS,建立三维的"超弹性体"的两参数Mooney-Rivlin橡胶模型、弹簧和"刚体"的静止轴模型,研究传统唇型密封圈和2种新型唇形密封圈(G形与S形)在脱开过程中接触压力、接触宽度、摩擦力的变化规律,分析入口压力、过盈量、弹簧力、橡胶密度对脱开...     

氢冷汽轮发电机浮动环密封瓦结构创新设计研究进展

浮动环密封瓦是氢冷汽轮发电机的轴端关键密封件,提高其浮动性可有效降低耗氢量和提高发电机运行可靠性。综述氢冷发电机轴端密封发展历程中的3种典型产品：盘式密封瓦、环式密封瓦和以分段碳环密封为代表的先进浮动环式密封,简述各种浮动环密封瓦的结构特点和工作原理,分析密封瓦浮动性和氢气耗量的关键影响因素,重点探讨围绕以降低耗氢量、提高浮动性为目标的各类密封瓦结构和密封油系统创新设计方案及适用条件,为氢冷汽轮发电机轴端密封的技术研究和工程应用提供参考。     

Hydroforming of aluminum extrusion tubes for automotive applications. Part II: process window diagram

Based on the mathematical formulations for predicting forming limits induced by buckling, wrinkling and bursting of free-expansion tube hydroforming, a theoretical “Process Window Diagram” (PWD) is proposed and established in this paper. The theory developed in the first part of the present work was formulated within the context of free-expansion tube hydroforming with both combined internal pressure and end feeding. The PWD is designed to provide a quick assessment of part producibility for tube hydroforming. The predicted PWD is validated against experimental results conducted for 6260-T4 60×2×320 (mm) aluminum tubes. An optimal loading path is also proposed in the PWD with an attempt to define the ideal forming process for aluminum tube hydroforming. Parametric studies show that the PWD has a strong dependency on tube geometry, material property and process parameters. To the authors’ knowledge, this is the first attempt that a PWD is being formulated theoretically. Such a concept can be advantageous in deriving design solutions and determining optimal process parameters for tube hydroforming processes.     

阶梯收敛槽机械密封空化效应及密封性能优化分析

为解决波度端面机械密封精密加工困难的问题,基于收敛型槽具有较低的泄漏量和较高的流体静压效应的特点,提出一种由波度端面机械密封结构衍生变化的阶梯收敛槽机械密封结构,考虑空化作用,对不同结构参数及工况参数下机械密封密封性能进行CFD流体仿真分析。结果表明：工况参数及结构参数对液膜空化效应有显著的影响,其中随着膜厚、密封压力以及槽深的增加,液膜空化效应均减弱,随着转速的增大,液膜空化效应变强。以开漏比评价密封性能,结果表明,阶梯收敛槽机械密封在小膜厚、高转速、较低密封压力以及较小静环开槽深度下运行时可获得最优密封性能;但为保证密封端面液膜具有足够的承载力,开槽深度不宜过小。     

一种液压缸串联式组合密封及流场分析

针对液压缸传统的活塞密封,如接触密封、间隙密封存在的不足,将接触密封与间隙密封沿活塞轴向有机集成,提出一种新型串联式组合密封结构。建立该结构的数值分析模型,通过数值仿真获得流场压力分布、密封圈变形与内泄漏特性,以及结构参数对密封性能的影响规律。结果表明：在进出口压力相同的情况下,相比于接触密封,组合密封的内部结构中压力损失更大,密封圈受到的压力和冲击更小,有利于减少密封件变形;组合密封结构中端部的间隙密封对油液实施了阻滞,使中间的密封圈承受的油液冲击和压力变弱,因而密封圈变形更小;组合密封的多级密封结构能更好地屏蔽泄漏,提升密封性能;组合密封内泄漏受间隙密封长度、密封间隙和油液压力的影响,增大间隙密封长度、减小密封间隙和油液压力,可减少泄漏量。内泄漏物理实验进一步表明,该组合密封能有效减少内泄漏量,提高密封性能,且在密封圈出现损伤故障时,仍能在很大程度上抑制或减少内泄漏,提高密封效果与可靠性。     

密封试验夹具橡胶圈压量设计试验研究

针对实际现状,设计了一套密封试验夹具,通过多组试验,研究了橡胶圈压量以及沟槽同轴度对装配的影响,得到了当密封直径为105mm左右,胶圈直径3.55mm时,胶圈预压量为0.15～0.22mm,沟槽直径同轴度要求不大于0.05mm时,能够很好地保证零件在气压、油压、冲洗等试验中对密封元件的要求,保证压量适中、密封无泄漏的要求。     

阀门启闭件双密封装置

介绍一种具有大小两个启闭件并以快慢两阶段方式关闭阀门启闭件的密封装置。该密封装置是一种分别在大小两个启闭件上均装有环形橡胶密封圈和环形金属密封圈的双密封装置,在阀门关闭时,阀板上的环形橡胶密封圈与阀座先接触形成一道密封;在环形橡胶密封圈被稍微压缩后,阀板上的环形金属密封圈再与阀座接触又形成一道密封并承受整个启闭件上的压力;而环形橡胶密封圈良好的弹性变形减轻了启闭件关闭件时的冲击力,具有一定的消声减震性。     

内圆弧槽机械密封液膜流场特性分析

以内圆弧槽流体动压型机械密封为研究对象,建立了动静环端面间液膜的三维模型,运用计算流体动力学理论和有限体积法对端面间液膜的流场特性和装置的密封性能进行了模拟和数值分析。对处于不同工况、不同密封介质条件下的液膜流场,得到了其压力、泄漏量、开启力和摩擦扭矩的变化规律及相互影响关系。结果表明:圆弧槽能够产生明显的动压效应,动压效应的大小与动环转速呈正比;液膜的压力沿径向由内径到外径逐次降低;泄露量的大小随动环转速或介质压力的增大而增大;开启力的大小与动环端面的总压力具有相似的变化规律。     

螺旋槽机械密封泄漏率的控制方法

流体润滑的螺旋槽机械密封环端面在液膜摩擦热的作用下发生变形并构成径向楔形间隙。考虑液膜粘度随温度的变化，建立了液膜流动、密封环传热和热变形的耦合分析方法，依据该方法确定了与给定闭合力对应的端面间隙形式及泄漏率。研究表明，可通过调节闭合力可实现对泄漏率的控制；闭合力越大，液膜厚度越小，摩擦扭矩越大，泄漏率越小。