摘 要:针对某装置的活塞和缸体间存在着摩擦而易使密封失效的问题,介绍了几种常用于动密封的密封机理与密封结构形式,采用组合密封结构密封性能良好,导向环起定位和导向作用,挡圈起支承和定位作用,弹性橡胶圈提供预紧力并补偿密封环的磨损,密封环与油缸内孔形成配合而对偶面产生密封效果,组合密封结构能够满足使用要求。
关键词:动密封;密封机理;组合密封;
0 引 言
密封是防止泄露的有效方法,被密封介质往往是以穿漏、渗漏或扩散的形式通过密封件泄露的。因此,密封结构决定着设备的安全性、可靠性和耐久性。活塞密封是最常见的密封,影响活塞密封的因素是多方面的,比如密封件的质量,活塞的加工质量,结构设计的合理性。本文对O形密封圈、Y形密封圈和组合密封圈的密封机理和密封结构的优缺点进行了介绍,结合某装置活塞动密封实际使用情况进行说明,采用组合密封活塞密封性能良好。
1密封问题分析
装置的工作条件恶劣。在重载冲击的工作环境中,装置的运动部件要进行往复运动,接触部位的温度由于冲击急剧升高,进而导致普通密封很快失效。尤其是由于冲击力将外界固体颗粒或液体将进入活塞与缸体内壁之间的间隙,使运动部件发生腐蚀磨损和磨料磨损,导致运动部件很快报废,进而导致装置不能正常工作。要提高该装置的使用寿命,密封结构的设计需要考虑由于冲击而产生的摩擦热、由于冲击而带入活塞间隙的固体颗粒或液体、活塞表面的润滑等。
2动密封的密封机理
常用的适用于往复运动的动密封结构形式主要有:O形密封圈密封、唇形圈密封和组合密封GDKK密封,下面分别介绍这几种动密封的密封机理和密封结构存在的不足。
2.1 O形密封圈密封机理
O形密封圈是一种挤压型密封,其密封机理是依靠密封件发生弹性变形,在密封接触面上造成接触压力,接触用作往复运动密封件时,其预密封作用和自密封作用与用作静密封时一样。但由于活塞杆往复运动时很容易将液体带到O形圈和活塞杆之间,导致发生黏附泄露,情况比静密封复杂。当往复运动时,密封是依靠密封件与运动活塞杆之间流体膜的弹性流体动压效应来实现的。活塞杆的动密封及润滑机理决定于由活塞杆带入密封界面液压流体的行为。首先,在外行程过程中,密封件应能将大部分液压流体刮离液压杆表面,但不可避免地总有一层很薄的液体被带入密封件与液压杆间的界面,形成一充满液体的密封间隙,这一间隙很少超过。如果每一个运动方向的该间隙可以计算确定,则流体通过密封件的流量可以确定,泄露率和摩擦力则可预测。
2.2 Y形密封圈的密封机理:
Y形圈依靠其张开的唇边贴于密封副耦合面。无内压时,仅仅因唇尖的变形而产生很小的接触压力。在密封的情况下,受内压作用,与介质接触的每一点上均有与内压相等的法向压力,所以Y形圈底部将受到轴向压缩,唇部受到周向压缩,唇与密封面接触变宽,同时接触压力增大。当内压再升高时,接触压力的分布和大小进一步改变,唇部与密封面配合更紧密,密封性更好,这就是Y形圈的自密封作用。由于这种自密封作用,一个Y形圈能有效地封住32MPa的高压。
Y形圈对偏心载荷和偏心运动的适应性并不强。当活塞的运动和受力遇到偏心时,为了避免唇部偏心磨损,常在密封之间设一抗磨环。抗磨环的材料应耐磨并具有自润滑性,一般采用尼龙或聚四氟乙烯。
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2.3 组合密封GDKK的密封机理
GDKK组合密封由密封环、两个导向环、两个挡圈、一个弹性橡胶圈组成。导向环起定位和导向作用,挡圈起到支承和定位作用,弹性橡胶圈提供预紧力并补偿密封环的磨损,密封环与油缸内孔形成配合而对偶面产生密封效果,具有双向密封效果,如图1所示为密封结构示意图。导向环采用材料是聚四氟乙烯PTFE,该种材料具有自润滑性,耐磨性能优异,与金属表面无粘着作用,摩擦阻力小的优点,而聚四氟乙烯PTFE的最大缺点是缺乏弹性,没有自密封能力,而弹性橡胶圈具有良好的弹性,从而使组合式密封圈具有自密封能力。这种组合密封利用了聚四氟乙烯PTFE低的摩擦系数和磨损系数,由此降低了密封件的摩擦系数,提高了密封的可靠性和使用寿命。
1——导向环;2——挡圈;3——弹性橡胶圈
图1 组合密封示意图
3应用举例
如图2所示为液压缸中往复运动密封结构,活塞在往复运动中通常需要对两个方向的压力介质实现密封,活塞杆伸出元件外部,即要严格阻止油液泄露至外部,又要防止外部的水、气和杂质侵入元件。弹性橡胶圈提供预紧力,与滑移表面的摩擦因数低,摩擦特性好,对密封装置的机械加工精度低,不会出现爬行的优点;导向环起定位和导向作用,防止液压缸烧结,提高运动平稳性;挡圈起支承和定位作用,防止弹性橡胶圈发生挤出现象,提高其使用压力,组合密封结构能够满足液压缸使用要求。
![](/userUpload/8(10804).png)
1——活塞;2——挡圈;3——导向环;4——弹性橡胶圈;5——活塞杆
图2 液压缸密封结构示意图
4结束语
本文对常用的适用于往复运动的动密封结构形式O形密封圈密封、唇形圈密封和组合密封GDKK的密封机理和密封结构存在的不足进行了介绍,并且结合某装置的活塞和缸体间动密封进行应用举例,采用导向环、挡圈和弹性橡胶圈的组合密封GDKK,实现了活塞和缸体间在工作时的动密封要求,保证了机械密封件的动、静密封端面能够紧密贴合,防止密封端面剧烈磨损,提高了密封的可靠性和使用寿命。该方法也为苛刻工况条件下动密封的解决提供了一种有效方法和途径。
参考文献
[1](德)海因茨K.米勒、(英)伯纳德S.纳乌、程传庆译.流体密封技术—原理与应用[M].北京:机械工业出版社,2002.6.
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[3] 明宇密封产品说明书. 太仓市明宇密封件有限公司. 2009年第6版.