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1、<p>  The hydraulic presses system of the form and the evaluation</p><p>  The hydraulic presses the component to carried out to standardize gradually, the series turn, its specification, species, quant

2、ity, functionses all had to raise very greatly, particularly is to adopt the new craft of new technique of electronics technique, servo technique...etc. after, the hydraulic presses the exaltation that the quantity of th

3、e system gets to show the highest , it developped the important function in national economy and the military industries.</p><p>  Set out from the different angle, can press the system to the liquid to be d

4、ivided into the different form.</p><p>  1)Press the circulating way of the oil liquid, the liquid press the system and can is divided into the open type system and shut type systems.The open type system mea

5、n that the liquid presses the pump to absorb the oil from the fuel tank, the oil is through various control valve, driving the liquid to press to carry out the component, returning to oil to has been changed to return to

6、 fuel tank toward valve again.This kind of system structure is more simple, can develop the fuel tank to spread ho</p><p>  2)According to system the liquid presses the number of the pump, can is divided int

7、o the list pump system, double pump system and pump system more.</p><p>  3)Press the dissimilarity of pump the form with the liquid by, can is divided into the fixed amount pump system and change the quanti

8、ty pump system.The advantage that changes to measure the pump is to regulate the scope inside, can make use of the power of launch the machine well, but its structure and the manufacturing craft complications, the cost i

9、s high, can is divided in to move to change the quantity, control to change the quantity possibly, servo change the quantity, pressure to compensat</p><p>  4)Press toward performance the component to provid

10、e the dissimilarity of the oil method, can is divided in to establish the system and merge the system.Establish in the system, it is next performance component that previous performance component return to oil of into oi

11、l, pass a performance component pressure and will lower once each time.In establish system, the each performance component that be the lord pump toward many roads valve control provides the oil, as long as the liquid p

12、resses the</p><p>  The whole liquid presses to spread the good and bad of move the machine function, mainly being decided by the quality that the liquid presses the system function, including the component

13、quantity good and bad use, basic back track whether fitting etc..The quality of the system function, in addition to satisfying to use the function to request, should make use of, adjust from the efficiency, power that th

14、e liquid press the system soon scope and tiny adjust characteristic, vibration and voice of n</p><p>  The modern engineering machine almost adopts the liquid to press the system, and combine with electronic

15、s system, the calculator control technique, the importance that become the modern engineering machine constitutes the part.</p><p>  液壓系統(tǒng)的形式及評(píng)價(jià)</p><p>  液壓元件逐步實(shí)現(xiàn)了標(biāo)準(zhǔn)化、系列化,其規(guī)格、品種、質(zhì)量、性能都有了很大提高,尤其是采

16、用電子技術(shù)、伺服技術(shù)等新技術(shù)新工藝后,液壓系統(tǒng)的質(zhì)量得到了顯著的提高,其在國(guó)民經(jīng)濟(jì)及軍事工業(yè)中發(fā)揮了重大作用。從不同的角度出發(fā),可以把液壓系統(tǒng)分成不同的形式</p><p>  1)按油液的循環(huán)方式,液壓系統(tǒng)可分為開(kāi)式系統(tǒng)和閉式系統(tǒng)。開(kāi)式系統(tǒng)是指液壓泵從油箱吸油,油經(jīng)各種控制閥后,驅(qū)動(dòng)液壓執(zhí)行元件,回油再經(jīng)過(guò)換向閥回油箱。這種系統(tǒng)結(jié)構(gòu)較為簡(jiǎn)單,可以發(fā)揮油箱的散熱、沉淀雜質(zhì)作用,但因油液常與空氣接觸,使空氣易于滲入

17、系統(tǒng),導(dǎo)致機(jī)構(gòu)運(yùn)動(dòng)不平穩(wěn)等后果。開(kāi)式系統(tǒng)油箱大,油泵自吸性能好。閉式系統(tǒng)中,液壓泵的進(jìn)油管直接與執(zhí)行元件的回油管相連,工作液體在系統(tǒng)的管路中進(jìn)行封閉循環(huán)。其結(jié)構(gòu)緊湊,與空氣接觸機(jī)會(huì)少,空氣不易滲入系統(tǒng),故傳動(dòng)較平穩(wěn)。工作機(jī)構(gòu)的變速和換向靠調(diào)節(jié)泵或馬達(dá)的變量機(jī)構(gòu)實(shí)現(xiàn),避免了開(kāi)式系統(tǒng)換向過(guò)程中所出現(xiàn)的液壓沖擊和能量損失。但閉式系統(tǒng)較開(kāi)式系統(tǒng)復(fù)雜,因無(wú)油箱,油液的散熱和過(guò)濾條件較差。為補(bǔ)償系統(tǒng)中的泄漏,通常需要一個(gè)小流量的補(bǔ)油泵和油箱。由于單

18、桿雙作用油缸大小腔流量不等,在工作過(guò)程中會(huì)使功率利用下降,所以閉式系統(tǒng)中的執(zhí)行元件一般為液壓馬達(dá)。</p><p>  2)按系統(tǒng)中液壓泵的數(shù)目,可分為單泵系統(tǒng),雙泵系統(tǒng)和多泵系統(tǒng)。</p><p>  3)按所用液壓泵形式的不同,可分為定量泵系統(tǒng)和變量泵系統(tǒng)。變量泵的優(yōu)點(diǎn)是在調(diào)節(jié)范圍之內(nèi),可以充分利用發(fā)動(dòng)機(jī)的功率,但其結(jié)構(gòu)和制造工藝復(fù)雜,成本高,可分為手動(dòng)變量、盡可能控變量、伺服變量、壓

19、力補(bǔ)償變量、恒壓變量、液壓變量等多種方式。</p><p>  4)按向執(zhí)行元件供油方式的不同,可分為串聯(lián)系統(tǒng)和并聯(lián)系統(tǒng)。串聯(lián)系統(tǒng)中,上一個(gè)執(zhí)行元件的回油即為下一個(gè)執(zhí)行元件的進(jìn)油,每通過(guò)一個(gè)執(zhí)行元件壓力就要降低一次。在串聯(lián)系統(tǒng)中,當(dāng)主泵向多路閥控制的各執(zhí)行元件供油時(shí),只要液壓泵的出口壓力足夠,便可以實(shí)現(xiàn)各執(zhí)行元件的運(yùn)動(dòng)的復(fù)合。但由于執(zhí)行元件的壓力是疊加的,所以克服外載能力將隨執(zhí)行元件數(shù)量的增加而降低。并聯(lián)系統(tǒng)中,

20、當(dāng)一臺(tái)液壓泵向一組執(zhí)行元件供油時(shí),進(jìn)入各執(zhí)行元件的流量只是液壓泵輸出流量的一部分。流量的分配隨各件上外載荷的不同而變化,首先進(jìn)入外載荷較小的執(zhí)行元件,只有當(dāng)各執(zhí)行元件上外載荷相等時(shí),才能實(shí)現(xiàn)同時(shí)動(dòng)作。    </p><p>  全液壓傳動(dòng)機(jī)械性能的優(yōu)劣,主要取決于液壓系統(tǒng)性能的好壞,包括所用元件質(zhì)量?jī)?yōu)劣,基本回路是否恰當(dāng)?shù)?。系統(tǒng)性能的好壞,除滿足使用功能要求外,應(yīng)從液壓系統(tǒng)的效率、

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