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1、<p><b> 附 錄 A</b></p><p> The working principle of gear pump</p><p> By into the internal gear pump a pair of gear, gear of two side have cover, shell, cover and gear of ea
2、ch tooth formed many seal groove between work cavity. When gear as shown on the right direction rotates, oil absorption cavity due to mesh with each other in engagement gradually withdraw, seal volume increase gradually,
3、 vacuum forming part of the oil in the tank, so outside the atmospheric pressure, the function of the oil absorption, oil absorption into the cavity, the gear, and as full of sl</p><p> I n terms of speakin
4、g, the gear pump also called positive displacement device, that is like a cylinder piston, when in a tooth into another tooth fluid, liquid space by mechanical discharged. To squeeze Because liquids as incompressible, so
5、 the liquid and tooth can occupy the same space at the same time, such, liquid was ruled out. Because of the constant mesh, this phenomenon is in continuous occur, thus also in the pump export provides a continuous remov
6、al amount, pump every around, the amount</p><p> In fact, there were a small amount of the pump fluid loss, which make the pump efficiency can't reach 100%, because these fluid is used to lubricating be
7、arings and gear, and on both sides of the pump body can't without clearance fit, so can't make fluid from export 100% from a small amount of fluid loss, so is inevitable. However pump can still operating well, fo
8、r most extrusion material, it can still reach 93% ~ 98% of efficiency. For viscosity or density in the process of change, this pump is </p><p> For a pump rotation speed, in fact, there is a limit, it mainl
9、y depends on process flow, if the transfer of oil, it can pump is at high speed rotating, but when the fluid is a kind of high viscosity polymer melt, the restrictions will be significantly reduced. Promote high sticky f
10、luid into the suction side of the two tooth space is very important, if the space did not fill, it can't pump discharge accurate flow, so the PV value (pressure x velocity is also a) a limiting factor, and it's a
11、 proce</p><p><b> 附 錄 B</b></p><p><b> 齒輪泵的工作原理</b></p><p> 輪泵由裝在殼體內(nèi)的一對(duì)齒輪所組成,齒輪兩側(cè)有端蓋,殼體、端蓋和齒輪的各個(gè)齒間槽組成了許多密封工作腔。當(dāng)齒輪按圖示方向旋轉(zhuǎn)時(shí),右側(cè)吸油腔由于相互嚙合的輪齒逐漸脫開,密封工作容積逐漸增大,
12、形成部分真空,因此油箱中的油液在外界大氣壓力的作用下,經(jīng)吸油管進(jìn)入吸油腔,將齒間槽充滿,并隨著齒輪旋轉(zhuǎn),把油液帶到左側(cè)壓油腔內(nèi)。在壓油區(qū)一側(cè),由于輪齒在這里逐漸進(jìn)入嚙合,密封工作腔容積不斷減小,油液便被擠出去,從壓油腔輸送到壓力管路中去。在齒輪泵的工作過程中,只要兩齒輪的旋轉(zhuǎn)方向不變,其吸、排油腔的位置也就確定不變。這里嚙合點(diǎn)處的齒面接觸線一直分隔高、低壓兩腔起著配油作用,因此在齒輪泵中不需要設(shè)置專門的配流機(jī)構(gòu),這是它和其它類型容積式液
13、壓泵的不同之處。齒輪泵的概念是很簡(jiǎn)單的,即它的最基本形式就是兩個(gè)尺寸相同的齒輪在一個(gè)緊密配合的殼體內(nèi)相互嚙合旋轉(zhuǎn),這個(gè)殼體的內(nèi)部類似“8”字形,兩個(gè)齒輪裝在里面,齒輪的外徑及兩側(cè)與殼體緊密配合。來自于擠出機(jī)的物料在吸入口進(jìn)入兩個(gè)齒輪中間,并充滿這一空間,隨著齒的旋轉(zhuǎn)沿殼體運(yùn)動(dòng),最后在兩齒嚙合時(shí)排出。</p><p> 在術(shù)語上講,齒輪泵也叫正排量裝置,即像一個(gè)缸筒內(nèi)的活塞,當(dāng)一個(gè)齒進(jìn)入另一個(gè)齒的流體空間時(shí),液體
14、就被機(jī)械性地?cái)D排出來。因?yàn)橐后w是不可壓縮的,所以液體和齒就不能在同一時(shí)間占據(jù)同一空間,這樣,液體就被排除了。由于齒的不斷嚙合,這一現(xiàn)象就連續(xù)在發(fā)生,因而也就在泵的出口提供了一個(gè)連續(xù)排除量,泵每轉(zhuǎn)一轉(zhuǎn),排出的量是一樣的。隨著驅(qū)動(dòng)軸的不間斷地旋轉(zhuǎn),泵也就不間斷地排出流體。泵的流量直接與泵的轉(zhuǎn)速有關(guān)。</p><p> 實(shí)際上,在泵內(nèi)有很少量的流體損失,這使泵的運(yùn)行效率不能達(dá)到100%,因?yàn)檫@些流體被用來潤滑軸承及齒
15、輪兩側(cè),而泵體也絕不可能無間隙配合,故不能使流體100%地從出口排出,所以少量的流體損失是必然的。然而泵還是可以良好地運(yùn)行,對(duì)大多數(shù)擠出物料來說,仍可以達(dá)到93%~98%的效率。對(duì)于粘度或密度在工藝中有變化的流體,這種泵不會(huì)受到太多影響。如果有一個(gè)阻尼器,比如在排出口側(cè)放一個(gè)濾網(wǎng)或一個(gè)限制器,泵則會(huì)推動(dòng)流體通過它們。如果這個(gè)阻尼器在工作中變化,亦即如果濾網(wǎng)變臟、堵塞了,或限制器的背壓升高了,則泵仍將保持恒定的流量,直至達(dá)到裝置中最弱的部
16、件的機(jī)械極限(通常裝有一個(gè)扭矩限制器)。 </p><p> 對(duì)于一臺(tái)泵的轉(zhuǎn)速,實(shí)際上是有限制的,這主要取決于工藝流體,如果傳送的是油類,泵則能以很高的速度轉(zhuǎn)動(dòng),但當(dāng)流體是一種高粘度的聚合物熔體時(shí),這種限制就會(huì)大幅度降低。 推動(dòng)高粘流體進(jìn)入吸入口一側(cè)的兩齒空間是非常重要的,如果這一空間沒有填充滿,則泵就不能排出準(zhǔn)確的流量,所以PV值(壓力×流速)也是另外一個(gè)限制因素,而且是一個(gè)工藝變量。由于這些限制,
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