液壓支架液壓閥的密封技術(shù)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.
液壓支架液壓閥的密封技術(shù)分析
液壓支架是采煤機(jī)械中的支護(hù)設(shè)備，經(jīng)過大修在井下一般可使用五年，但是液壓支架中各種液壓閥的使用壽命卻很低，長的3個(gè)月，短的只有幾個(gè)星期，國外解決的途徑和辦法是增加系統(tǒng)的過濾精度和提高乳化液的質(zhì)量，但收效不大。以英國某液壓閥為例，雖然加工精度及整個(gè)液壓系統(tǒng)的過濾精度都比較高，但因使用壽命低，已在我國面臨淘汰。
1）影響液壓閥密封性能的主要因素
密封元件損壞的主要因素是工作液中的雜質(zhì)。這些雜質(zhì)在密封元件間研磨，使閥產(chǎn)生泄漏。因此，國外曾提出相應(yīng)等級(jí)的液壓元件，應(yīng)采用相應(yīng)精度的過濾器。他們認(rèn)為5μM的油泵密封元件，如果采用過濾精度為3／μM的過濾器，壽命可比采用10μm的'提高10倍。但液壓支架用閥，工作環(huán)境十分惡劣。在采煤工作面，油管總長1000多米，接頭插口多達(dá)4000多個(gè)，液箱無特殊的防塵設(shè)施。乳化液中有大量的漂浮雜質(zhì)，在立柱缸底和閥腔，留有較多的煤粉、巖粒和鐵屑。進(jìn)液閥芯和閥座，由于開啟關(guān)閉比較頻繁，液體流速高，密封很快就會(huì)失效。實(shí)踐證明減少支架液壓系統(tǒng)液體的污染雜質(zhì)，是十分困難的，有人曾經(jīng)設(shè)想在乳化液泵站采用高壓過濾器，同時(shí)在每臺(tái)支架進(jìn)口處增加小型過濾器。但在工作中很快被堵塞，形成斷流。另一方面，隨著液壓支架技術(shù)的發(fā)展。對(duì)閥的使用性能和閥的使用壽命提出了更高的要求。目前，在裝有120目時(shí)的過濾器和磁過濾裝置的條件下，用通過被測試閥的乳化液的總流量和閥的啟閉次數(shù)，來計(jì)量閥的壽命。但實(shí)際上室內(nèi)型式試驗(yàn)與井下實(shí)際工作結(jié)果相差很大。現(xiàn)在許多國家的形式實(shí)驗(yàn)，增加了抗污染要求，有的是在乳化液中摻入適當(dāng)?shù)拿悍�，有的是加入機(jī)械雜質(zhì)。
為此，需要使用新型的、抗污染能力強(qiáng)的、適合于井下工作條件的密封副。
2）液壓閥密封材料的歷史及現(xiàn)狀
閥芯和閥座接觸面的泄漏，是工作液體分子擠入的結(jié)果。影響密封效果的主要原因是閥芯和閥座的接觸比壓、不平度及壓差。當(dāng)閥芯與閥座的接合面以P力壓緊，工作液體分子以F力擠入，密封材料會(huì)產(chǎn)生彈性變形。如果密封副總抗力大于分子斥力，則密封有效，否則就會(huì)形成泄漏。
早期的液壓支架，運(yùn)動(dòng)副之間沒有其他密封措施，是金屬直接接觸密封，即要求密封副接觸平面吻合，具有較高的加工精度，否則必須加大密封副的結(jié)合力，使接觸表面產(chǎn)生塑性變形，堵塞泄漏通道。
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