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本科生畢業(yè)設(shè)計(jì) (論文)
外 文 翻 譯
原 文 標(biāo) 題
Mechanical seal performance and a new technical
innovation
譯 文 標(biāo) 題
機(jī)械密封的性能及新型技術(shù)改造
作者所在系別
機(jī)電工程學(xué)院
作者所在專業(yè)
機(jī)械設(shè)計(jì)制造及其自動(dòng)化
作者所在班級
作 者 姓 名
作 者 學(xué) 號
指導(dǎo)教師姓名
指導(dǎo)教師職稱
企業(yè)指導(dǎo)教師
完 成 時(shí) 間
譯文標(biāo)題
機(jī)械密封的性能及新型技術(shù)改造
原文標(biāo)題
Mechanical seal performance and a new technical innovation
作 者
Masayuki INABA
譯 名
美男雅之
國 籍
日本
原文出處
University of Tokyo
譯文:
摘要:論文分析機(jī)械密封工作的基本原理,并且探討在各個(gè)環(huán)節(jié)中怎樣提高機(jī)械密封的性能和注意事項(xiàng),簡要介紹幾種先進(jìn)密封技術(shù)。
關(guān)鍵詞:機(jī)械密封性能,注意事項(xiàng),先進(jìn)密封技術(shù)
由于傳動(dòng)軸貫穿在設(shè)備內(nèi)外,這樣軸與設(shè)備之間存在一個(gè)圓周間隙,設(shè)備中的介質(zhì)通過該間隙向外泄露,如果設(shè)備內(nèi)壓力低于大氣壓,則空氣向設(shè)備內(nèi)泄露,因此必須有一個(gè)阻止泄露的軸封裝置。軸封的種類很多,由于機(jī)械密封具有泄漏量少和壽命長等優(yōu)點(diǎn),所以是當(dāng)今世界上最主要的軸密封方式。
機(jī)械密封主要是通過一系列零件將徑向密封轉(zhuǎn)化為軸向密封,在彈簧和介質(zhì)壓力共同作用下,對由于設(shè)備運(yùn)行所造成的軸向磨損可以及時(shí)補(bǔ)償,使軸向密封始終保持貼合。其密封性能和使用壽命取決于許多因素,如選型、機(jī)器的精度以及在安裝、啟動(dòng)前、運(yùn)行和停運(yùn)后的維護(hù)操作等。
1. 選型
機(jī)械密封按工作條件和介質(zhì)性質(zhì)的不同,有耐高溫、耐低溫機(jī)械密封,耐顆粒介質(zhì)機(jī)械密封和適應(yīng)易汽化的輕質(zhì)烴介質(zhì)的機(jī)械密封等,應(yīng)根據(jù)不同的用處選取不同結(jié)構(gòu)型式和材料的機(jī)械密封。在安裝與使用中要根據(jù)機(jī)械密封的要求選擇機(jī)器的精度,按轉(zhuǎn)軸的旋向來選擇彈簧的左、右旋。
2. 安裝
安裝方法隨機(jī)械密封型式、機(jī)器的種類不同而有所不同,但其安裝要領(lǐng)幾乎都相同,安裝步驟和注意事項(xiàng)如下:
2.1 安裝尺寸的正確確定。
2.2 裝入前,軸(軸套)、壓蓋應(yīng)無毛刺,軸承狀況良好;密封件、軸、密封腔、壓蓋都應(yīng)該清洗干凈。為減少摩擦阻力,軸上安裝機(jī)械密封的部位要薄薄地涂上一層油,以進(jìn)行潤滑,考慮到橡膠O形圈的相溶性,若不宜用油,可涂肥皂水。浮裝式靜環(huán)不帶防轉(zhuǎn)銷的結(jié)構(gòu),不宜涂油,應(yīng)干式裝入壓蓋。
2.3 先將靜環(huán)與壓蓋一起裝在軸上,注意不要與軸相碰,然后將動(dòng)環(huán)組件裝入。彈簧座或傳動(dòng)座的緊定螺釘應(yīng)分幾次均勻擰緊。
3. 啟動(dòng)前的準(zhǔn)備工作及注意事項(xiàng)
3.1 全面檢查機(jī)械密封,機(jī)械密封啟動(dòng)前進(jìn)行靜壓試驗(yàn),檢查是否有泄漏現(xiàn)象。
3.2 啟動(dòng)前應(yīng)保持密封腔內(nèi)充滿液體。對于輸送凝固的介質(zhì)時(shí),應(yīng)用蒸氣將密封腔加熱使介質(zhì)熔化按泵旋向盤車,檢查是否輕快均勻。如盤車吃力或不動(dòng)時(shí),則應(yīng)檢查裝配尺寸是否錯(cuò)誤,安裝是否合理。
4. 運(yùn)行中的維護(hù)
4.1 當(dāng)輸送介質(zhì)溫度偏高、過低、或含有雜質(zhì)顆粒、易燃、易爆、有毒時(shí),必須采取相應(yīng)的阻封、沖洗、冷卻、過濾等措施。
4.2 運(yùn)轉(zhuǎn)前用手盤車,注意轉(zhuǎn)矩是否過大,有無擦碰及不正常的聲音。
4.3 注意旋向,聯(lián)軸器是否對中,軸承部位的潤滑油加法是否適當(dāng),配管是否正確。
4.4 運(yùn)轉(zhuǎn)前首先將介質(zhì)、冷卻水閥門打開,檢查密封腔內(nèi)的氣體是否全排出,防止靜壓引起泄漏,然后開機(jī)運(yùn)行。
4.5 開車后是否正常穩(wěn)定,有無因軸轉(zhuǎn)動(dòng)引起的異常轉(zhuǎn)矩,以及異常響聲和過熱現(xiàn)象。
5. 停運(yùn)
5.1 對于用泵外封油系統(tǒng)的機(jī)械密封,應(yīng)先啟動(dòng)封油系統(tǒng)。停車后最后停止封油系統(tǒng)。
5.2 熱油泵停運(yùn)后不能馬上停止封油腔及端面密封的冷卻水,應(yīng)待端面密封處油溫降到80度以下時(shí),才可以停止冷卻水,以免損壞密封零件[3]。
6. 新型技術(shù)改造
為了提高機(jī)械密封的可靠性和壽命,降低磨損,出現(xiàn)了采用新材料和新工藝的各種機(jī)械密封技術(shù)。目前先進(jìn)的機(jī)械密封應(yīng)用技術(shù)主要有密封端面改形技術(shù)、控制平衡比密封技術(shù)、組合密封技術(shù)和可控機(jī)械密封技術(shù)等,都可以改變機(jī)械密封的性能。
下面主要介紹一下密封端面改形技術(shù)。密封端面改形技術(shù)就是通過在密封端面上開各種形式的槽來改善端面件的潤滑情況,從而實(shí)現(xiàn)機(jī)械密封的長壽命運(yùn)行,它是當(dāng)今機(jī)械密封領(lǐng)域的高新技術(shù)。
6.1 干氣密封技術(shù)
外側(cè)加工有均勻分布的2.5-10um的動(dòng)壓槽,當(dāng)東環(huán)旋轉(zhuǎn)時(shí),流體動(dòng)壓槽把外側(cè)的高壓隔離氣體泵入密封端面之間,由外徑至槽根部氣膜壓力逐漸增加,而自槽根部至內(nèi)徑處氣膜壓力逐漸下降,因端面膜壓增加使所形成德爾開啟力大于作用在密封環(huán)上的閉合力,在摩擦副之間形成很薄的一層氣膜,從而使米粉工作在非接觸狀態(tài)下,所形成的氣膜完全阻塞了相對低壓的密封介質(zhì)泄露通道,實(shí)現(xiàn)了密封介質(zhì)的零泄露。
這種密封運(yùn)行無磨損,功耗?。恍孤读啃?,可實(shí)現(xiàn)零泄露;結(jié)構(gòu)相對簡單,無需復(fù)雜的油封系統(tǒng),安裝維護(hù)費(fèi)用低;系統(tǒng)可靠,可實(shí)現(xiàn)長周期穩(wěn)定運(yùn)行。
干氣密封端面的槽形主要分單旋向和雙旋向兩類。單旋向槽形只可使用于單向旋轉(zhuǎn)的轉(zhuǎn)動(dòng)設(shè)備,在要求的旋向下才可產(chǎn)生開啟力,如反轉(zhuǎn)則產(chǎn)生負(fù)的開啟力而可能導(dǎo)致密封的損壞。但相對于雙旋向的槽形,它可形成更大的開啟力和氣膜剛度,產(chǎn)生更高的穩(wěn)定性而更可靠的防止端面接觸。故在很低的轉(zhuǎn)速下和較大的振動(dòng)下也可使用,在目前也是使用最多的。雙向槽無旋向要求,正反轉(zhuǎn)皆可使用。轉(zhuǎn)子的反轉(zhuǎn)不會(huì)造成密封的損壞。其使用范圍較單旋向槽寬,但其穩(wěn)定性、抗干擾能力較單向旋向差。
6.2 上游泵送密封
上游泵送密封的工作原理與干氣密封類似,是借助密封環(huán)斷面內(nèi)側(cè)開設(shè)的流體動(dòng)壓槽在旋轉(zhuǎn)條件下的粘性剪切作用把液體泵入密封端面之間,使液膜的壓力增加并把兩密封端面分開;與干氣密封不同之處在于,上游泵送密封的端面液體動(dòng)壓槽式把由高壓側(cè)泄露至低壓側(cè)的被密封液體重新反輸志高壓側(cè),以消除密封介質(zhì)由高壓側(cè)想低壓側(cè)的泄露。
6.3 端面開深槽流體靜壓型機(jī)械密封
端面開深槽流體靜壓型機(jī)械密封是在密封端面上開出幾組深度達(dá)幾毫米的凹槽或孔和壓力介質(zhì)引入孔,將密封流體或外界潤滑流體引入密封端面,從而對密封端面進(jìn)行充分潤滑和冷卻。在結(jié)構(gòu)上有自加壓凹槽式和外加壓凹槽式等。自加壓凹槽式在非旋轉(zhuǎn)的外周開若干個(gè)小孔并與端面開出的環(huán)形凹槽相通,從而將被密封的壓力介質(zhì)引入密封端面;外加壓凹槽式非旋轉(zhuǎn)環(huán)圓周外的小孔不與密封介質(zhì)相通,而與外界起潤滑作用的流體源相通,將外界流體引入密封端面進(jìn)行潤滑和冷卻。端面開深槽流體靜壓型機(jī)械密封,由于壓力介質(zhì)引入端面,平衡了閉合力,從而使兩端面分開成為非接觸型機(jī)械密封,盡管泄漏量比較大,一般為每小時(shí)幾百毫升,遠(yuǎn)大于常規(guī)機(jī)械密封泄漏量,但仍廣泛用于高壓、高速、高溫等普通機(jī)械密封難于勝任的工況。
為了揭示機(jī)械密封有關(guān)規(guī)律,提高機(jī)械密封端面參數(shù)測試的可靠性與研究是關(guān)鍵。納米材料的特殊性能有助于改善機(jī)械密封端面間潤滑狀態(tài),開發(fā)納米材料機(jī)械密封和應(yīng)用納米沖洗液將是機(jī)械密封研究的近期目標(biāo)。隨著經(jīng)驗(yàn)的完善和技術(shù)的發(fā)展,機(jī)械密封將越來越成熟,逐步走向零泄露,長期穩(wěn)定運(yùn)行。
原文:
Abstract: the paper analyses the basic principle of mechanical seal, and discusses how to improve the performance of mechanical seals in each link and the matters needing attention, several advanced seal technology are briefly introduced.
Key words: mechanical seals, Performance Matters, needing attention, Advanced sealing technology
Due to the drive shaft through both inside and outside the equipment, so there is a circumferential clearance between shaft and equipment, equipment of medium leak out through the gap, if the device internal pressure below atmospheric pressure, the air to leak inside equipment, so there must be a stop leaking of shaft seal device. Many different kinds of shaft seal, mechanical seal has the advantages of less leakage and long service life, so is the main shaft seal way in the world today.
Mainly through a series of mechanical seal parts axial radial seal can be converted to seal, in the spring and medium pressure, under the function of the equipment operation caused by the axial wear can timely compensation, make the axial seal always stay fit. The sealing performance and service life depends on many factors, such as type selection, the precision of the machine, and before the installation, start-up, operation and shut down after the maintenance operation, etc.
1. The selection of
Mechanical seal according to the working conditions and the properties of medium, there are high temperature resistant, resistant to low temperature mechanical seal, granular medium resistance of mechanical seal and adapt easy vaporization of light hydrocarbon medium mechanical seal, etc., should choose different according to different use of the structural type and materials of mechanical seal. In the installation and use to select according to the requirement of the mechanical seal the precision of the machine, according to the axis of rotation always choose spring left and right hand.
2. Install
Installation method according to the mechanical seal type and the type of machine is different, but the installation essentials are almost the same, the installation steps and matters needing attention are as follows:
2.1 installation of right determine size.
2.2 prior to loading, axial (collar), gland should be no burr, bearing in good condition; Seal, shaft, sealing cavity, gland should be cleaned. In order to reduce frictional resistance, and shaft installed on mechanical seal parts to thin coated with oil, for lubrication, considering the intermiscibility of rubber o-ring, if not oil, can besmear soap and water. Without a stop pin float mounted static ring structure, not oil, should be dry load a gland.
2.3 to static ring mounted on the shaft with gland, be careful not to into the shaft, then load ring components. Spring bridge or transmission of evenly tighten the set screws should be several times.
3. Before the start of the preparation work and the matters needing attention
3.1 overall check mechanical seal, mechanical seal before the start of hydrostatic test, check whether there is leakage phenomenon.
3.2 before the start of sealed cavity filled with liquid shall be maintained. For solidification of the medium, the application of steam seal chamber heating melt medium according to the pump rotate to turning, check whether the light evenly. Such as turning demanding or not move, should check whether assembly size error, installation is reasonable.
4. The running maintenance
4.1 when the temperature of the medium to high, low, or containing impurity particles, inflammable, explosive, toxic, must adopt corresponding resistance sealing and flushing, cooling, filtering and other measures.
4.2 before turning by hand operation, pay attention to whether the torque is too big, any scratch and abnormal sound.
4.3 turn to pay attention to, and whether the coupling of, the bearing parts of the lubricating oil additive is appropriate, piping is correct.
4.4 before the first operation will be medium, the cooling water valve is open, check the gas in the sealed cavity is completely discharge, to prevent leaks by static pres
4.5 is normal after driving stability, have without shaft turning caused by abnormal torque, as well as the abnormal noise and overheating.
5. Stop
5.1 with WaiFeng oil pump system of mechanical seal, should start the seal oil system. Stop after the last stop in sealing system.
5.2 hot oil pump shut down not immediately stop after the oil seal cavity and end face seal cooling water, should be end face seal oil temperature has dropped below 80 degrees, can stop the cooling water, so as not to damage sealing parts .
6. New technological upgrading
In order to improve the reliability and life of the mechanical seal, reduce wear and tear, the adoption of new materials and new technology of all kinds of mechanical seal technology. Has the advanced mechanical seals used technology mainly have the seals to shape, control balance ratio sealing technology, combined sealing technology and controllable mechanical seal technology, etc., can change the mechanical seal performance.
Here mainly introduce the seals fractal technology. Seal face to fractal technology is through the various forms of trough on seal face to improve the face lubrication conditions, so as to realize the long life of mechanical seal, it is a high and new technology in the field of mechanical seal today.
6.1 a dry gas seal technology
Dry gas seal is a slotted sealing technology used in gas sealing, belongs to the non-contact seal. On the outside of a sealing ring end face of dry gas seal processing has a uniform distribution of dynamic pressure groove of 2.5-10 um, as east ring rotates, fluid dynamic pressure groove to the outside of the high voltage isolation between gases pumped into the seals, gas film from the outside diameter to the groove root pressure increase gradually, and the groove root of air film pressure gradually decreases from the inner diameter, because the face film formed by the pressure increase del open force is greater than the effect on the sealing ring closing force, between friction pair in the formation of a thin layer of gas film, so that the rice noodles work in non contact mode, the formation of the gas film completely blocked the relatively low pressure sealing medium leakage channel, to achieve zero leakage of sealing medium.
The sealing run without wear and tear, low consumption; Leak quantity is small, which can realize zero leakage; Structure is relatively simple, no complicated oil seal system, the low cost of installation and maintenance; System is reliable, which can realize stable operation for a long period of time.
Trough the main points of dry gas seal face of single screw and twin twist to the two classes. Single screw to the trough can be used only in unidirectional rotating rotating equipment, in spin down before the requirements can produce open, such as inversion produces negative and may cause the damage of seal opening force. But relative to the twin twist to the channel, it can form a bigger opening force and film stiffness, higher stability and more reliable protection against contact face. Reason under the low speed and large vibration can also be used, in the present is the most used. A two-way channel to require irrotational, positive &negative all can use. The reversal of the rotor will not result in damage to seal. The use scope is single screw to the groove width, but its stability, anti-interference ability is ChanXiangXuan to the poor.
6.2 the upstream pumping seal
Working principle of upstream pumping seal and dry gas seal, is by opening the seal ring cross section inside the fluid dynamic pressure groove under the condition of the rotation of the viscous shearing action between pumping the liquid seal face, make the liquid film pressure increases and separate the two seal face; Differs, dry gas seal and upstream pumping seal end of fluid dynamic pressure groove reveal your is composed of high voltage side to low voltage side of the sealed fluid to lose ambition high side, in order to eliminate the sealing medium is composed of high voltage side to low voltage side of the leak.
6.3 face deep groove type hydrostatic mechanical seal
Face deep groove type hydrostatic mechanical seal is on the seal face a few group of groove depth of a few millimeters or holes and pressure medium into the hole, the seal fluid or external lubrication fluid is introduced into the seals, and thus sufficient lubrication and cooling of the seals. In structure with the pressure groove and pressure groove outside, etc. Since the pressure groove type several small opening in the non-rotating peripheral and and end face of the ring grooves are interlinked, thus introducing the pressure of seal medium sealing end surface; Outside pressure groove type of rotating ring circumferential outer holes and sealing medium are interlinked, and lubrication fluid source communicates with the outside world, introducing the fluid seals for lubrication and cooling. Face deep groove type hydrostatic mechanical seal, because of the pressure medium is face, balance the closing force, so that two separate become a non-contact type mechanical seal, despite leakage is larger, general hundred milliliters per hour, far more than the conventional mechanical seal leakage, but it is still widely used in ordinary mechanical seal of high pressure, high speed and high temperature, working condition is difficult to do it.
In order to reveal the mechanical seal related laws, improve the reliability of parameters of mechanical seal face test and research is the key. Special properties of nanomaterials is helpful to improve the lubrication condition between the mechanical seal face, development of nano-materials mechanical seal mechanical seal research and application of nano rinses will be short-term goals. With the improvement of the experience and the development of technology, mechanical seal will be more and more mature, step by step towards zero leakage, long-term stable operation.
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