液压支架液压阀的密封技术分析
The liquid presses the support liquid to press the valve to seal completely the technique analysisThe liquid press the support is to adopt the coal machine in of pay and protect equipments, pass by to fix greatly and can use five years generally under the well, but the liquid press the support to press the service life of the valve in various liquid but very low, long 3 months, short only a few week, the path and ways that abroad solve are percolation accuracy and exaltations that increases the system to emulsify the quantity of the liquid, but yield results not greatly.To take British some liquid press valve as an example, although process the percolation accuracy that accuracy and the whole liquids press the system all higher, is low because of the service life, have already faced to eliminate in the our country.
1）Affect the liquid presses main factor that the valve seals completely the function
The main factor that seals completely the component damage is miscellaneous quality within the work liquid.These miscellaneous quality at seal completely the component grind, make the valve creation leak.Therefore, the abroad once puts forward the liquid that corresponds the grade to press the component, should adopt the filter of correspond the accuracy.They think that 5 oil pumps of the μ M seal completely the component, if the adoption filter the accuracy is the filter of the 3/ μ M, the life span can compare to adopt 10 μ Ms to raise 1000%.
But the liquid press the support to use the valve, the work environment is very bad.At adopt the coal work to face, total long more than 1000 rices of pipeline, deal with contact to put in a word to amount to more than 4000s more, the liquid box has no special dust palliative facilities.Emulsify to have a great deal of quality with miscellaneous flotage in the liquid at signing a bottom of pillar , stay to have the more coal powder, the rock grain and scraps of irons.Enter the liquid valve heart and the valves, because of openning the close more multifarious, the liquid current velocity is high, seal completely very quickly lose efficacy.Practice the certificate decrease support liquid presses the system liquid to pollute the miscellaneous quality, is very difficult, someone has ever conceive at emulsify the liquid pump station adoption high pressure filter, import a filter with small scaled increment at the each pedestal support at the same time.But was very quickly stop in the work, become to break to flow.
On the other hand, press the technical development of support along with the liquid[12].Put forward the higher request to the usage function of the valve and the service life of the valve.Currently, under the condition of having 120 eyes of filter, use to pass to be test total discharge and the opening of the valves that the valve emulsifies the liquid shut the number of times life span of calculate the valve.But the actually indoor pattern experiment with well next actual work result differ very big.Now many form experiment of nation, increased the anti- pollution request, have plenty of to add in emulsify liquid appropriate of coal powder, have plenty of to join the miscellaneous quality of machine.
For this, need to be use new, anti- pollution the ability is strong, suitable for well next the work seals completely conditionally vice-.
2）The liquid presses the history and the present condition that the valve seals completely the material
The leakiness that the valve heart and valve contacts face, is the result that the work liquid member crush into.The influence seals completely the main reason of result is the valve heart and the contact of the valves to compare to press, the gravamen degree and press bad.When the valve heart and the coalescence of the valves face to compress tightly with the P dint, the work liquid member crushes into with the F dint, seal completely the material and will produce the flexibility to transform.If seal completely the vice-president resistance big scold the dint in the member, then seal completely effectively, otherwise will become the leakiness.
The liquid of the earlier period presses the support, exercise the vice- have no other seal completely the measure, is a metals to get in touch with to seal completely directly, then request to seal completely the vice- contact flat surface to fit together, having to process the accuracy higherly, otherwise must the enlargement seal completely to combine the dint vice-ly, making get in touch with the surface creation to transform, stopping the leakiness passage.
液压支架液压阀的密封技术分析
液压支架是采煤机械中的支护设备，经过大修在井下一般可使用五年，但是液压支架中各种液压阀的使用寿命却很低，长的3个月，短的只有几个星期，国外解决的途径和办法是增加系统的过滤精度和提高乳化液的质量，但收效不大。以英国某液压阀为例，虽然加工精度及整个液压系统的过滤精度都比较高，但因使用寿命低，已在我国面临淘汰。
1）影响液压阀密封性能的主要因素
密封元件损坏的主要因素是工作液中的杂质。这些杂质在密封元件间研磨，使阀产生泄漏。因此，国外曾提出相应等级的液压元件，应采用相应精度的过滤器。他们认为5μM的油泵密封元件，如果采用过滤精度为3／μM的过滤器，寿命可比采用10μm的'提高10倍。但液压支架用阀，工作环境十分恶劣。在采煤工作面，油管总长1000多米，接头插口多达4000多个，液箱无特殊的防尘设施。乳化液中有大量的漂浮杂质，在立柱缸底和阀腔，留有较多的煤粉、岩粒和铁屑。进液阀芯和阀座，由于开启关闭比较频繁，液体流速高，密封很快就会失效。实践证明减少支架液压系统液体的污染杂质，是十分困难的，有人曾经设想在乳化液泵站采用高压过滤器，同时在每台支架进口处增加小型过滤器。但在工作中很快被堵塞，形成断流。另一方面，随着液压支架技术的发展。对阀的使用性能和阀的使用寿命提出了更高的要求。目前，在装有120目时的过滤器和磁过滤装置的条件下，用通过被测试阀的乳化液的总流量和阀的启闭次数，来计量阀的寿命。但实际上室内型式试验与井下实际工作结果相差很大。现在许多国家的形式实验，增加了抗污染要求，有的是在乳化液中掺入适当的煤粉，有的是加入机械杂质。
为此，需要使用新型的、抗污染能力强的、适合于井下工作条件的密封副。
2）液压阀密封材料的历史及现状
阀芯和阀座接触面的泄漏，是工作液体分子挤入的结果。影响密封效果的主要原因是阀芯和阀座的接触比压、不平度及压差。当阀芯与阀座的接合面以P力压紧，工作液体分子以F力挤入，密封材料会产生弹性变形。如果密封副总抗力大于分子斥力，则密封有效，否则就会形成泄漏。
早期的液压支架，运动副之间没有其他密封措施，是金属直接接触密封，即要求密封副接触平面吻合，具有较高的加工精度，否则必须加大密封副的结合力，使接触表面产生塑性变形，堵塞泄漏通道。
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