【正文】 KL— 液壓系統(tǒng)泄漏系數(shù)，一般取 KL=～ ，取 KL=； max)( q? — 同時動作的各執(zhí)行元件所需流量之和的最大值。 將參數(shù)代入公式中，即： m in/1 4 01 2 Lq P ??? 但是有蓄能器補油，可以選擇 A10VS0100DR 1500r/min 時，流量 150L/min,功率 62 千瓦，尺寸 206X 液壓機的執(zhí)行件有兩個，即：主缸和 平衡 缸。電動機額定功率的確定必須根據(jù)消耗功率最大的工況來確定，因此要分別計算主缸、頂出缸各工況消耗的功率。 P=18X10^6 X 140/1000/60 /=45600W= 選擇電動機型號 Y250M4,額定功率 55 千瓦，電流 安培，轉(zhuǎn)速 15 1480 轉(zhuǎn)每分，效率 ，質(zhì)量 520千克，電動機尺寸 845X435. 四． 繪制液壓系統(tǒng)圖 五． 液壓元件的選擇 通過液壓系統(tǒng)的參數(shù)計算查閱 液壓手冊，液壓元件選擇如表 22 所示： 表 22 液壓元件明細(xì)表 序 號 液 壓 元 件 名 稱 元 件 型 號 數(shù)量 額定流量（ L/min） 廠家 1 油箱 1200 16 2 過濾器 ZUH250X10FS 1 250 太原液壓機械廠 3 液壓泵 A10VS0100 2 力氏樂 4 電磁溢流閥 DBW10200 1 QMAX=250 力氏樂 5 液控單向閥 2 Z2S6 11 力氏樂 液控單向閥 1 Z2S10 6 力氏樂 6 Y1， Y3， Y5， Y7 Y16,Y17 4WEH10E30 各 1 100 力氏樂 7 Y2， Y4， Y6， Y8，Y9， Y10， Y11，Y12 ， Y13 ，Y14,Y15 4WE6E5 各 1 60 力氏樂 9 單向節(jié)流閥 3 Z2SF10 6 力氏樂 10 單向節(jié)流閥 4 Z2SF6 4 力氏樂 12 溢流閥 18 DBDS8P1100 2 50 力氏樂 13 溢流閥 19 DBDS20P1100 2 250 力氏樂 14 蓄能器 NXQLF63/H, 1 63 奉化液壓件廠 15 電動機 Y250m44 1 17 泵站圖 18 六．液壓系統(tǒng)性能驗算 液壓系統(tǒng)壓力損失，壓力損失包括管路的沿程損失 △ p1 ，和管路的局部壓力損失 △ p2，和閥類元件的局部壓力損失 △ p3，總的壓力損失 △ p=△ p1+ △ p2+ △ p3 △ p1= ρ v^2l/d 。 式中 l管道的長度（ m） d管道的內(nèi)徑（ m） v 液流平均速度 (m/s) ρ 液壓油密度 (kg/m3) λ 沿程阻力系數(shù) ξ 局部阻力系數(shù) △ p3=△ pn(Q/Qn)^2 式中 Qn閥的額定流量 (m3/s) Q通過閥的實際流量 (m3/s) △ pn閥的額定壓力損失 (Pa), 矯直 機執(zhí)行部件有主缸和 平衡缸，夾送輥擺動缸，輥道升降缸，換輥馬達，下中輥高度調(diào)整液壓馬達 ，供油管子管徑如下 名稱 D1 D2 D3 D4 D5 D6 D7 內(nèi)徑 60.3 25.4 15.9 8 19 28.6 19 最后根據(jù)標(biāo)準(zhǔn) 軟管 取值如下 液壓油選用 LHL32 液 壓 油 ， 15 ℃時該油液的運動粘度scmcst / 2??? ,油液密度 3/920 mkg?? 。進油管長度為 3m，沿程壓力損失 1P? 為： PaPavdlP 6222111 2 ?????????? ??? 閥的壓力損失 PaP ??? 閥 ；那么進油路總的壓力損失 進P?為： 進P? = 1P? + 閥P? = PaPa 666 )( ????? 由于進出口管徑相同，要求工作速度相同，所以估算壓力損失也相同，那么回油壓力損失 也為 兆帕； △ p=+= 20 其他元件可以看成是和主缸并聯(lián)的，入出口輥道升降液壓缸速度比較高，做一驗算，其他元件忽略。進油管長度為 10m，沿程 壓力損失 1P? 為： PaPavdlP 6222111 ?????????? ??? 閥的壓力損失 PaP ??? 閥 ；那么進油路總的壓力損失 進P?為： 進P? = 1P? + 閥P? = PaPa 666 )( ????? 由于進出口管徑相同，要求工作速度相同，所以估算壓力損失也相同，那么回油壓力損失 也為 兆帕； △ p=+= 要求工作壓力 14 兆帕，而設(shè)計的是 18 兆帕，所以這點壓力損失對系統(tǒng)的工作幾乎沒有影響！ 通過對主缸、 入出口輥道升降 缸各工況的壓力損失驗算可知，液壓系統(tǒng)的油路構(gòu)及元件參數(shù)選擇滿足要求 。開始，我不會用 ＣＡＤ，在老師的強烈建議下，我學(xué)會了ＣＡＤ，出了我的第一張ＣＡＤ圖紙，雖然很糟糕，頗有詬病，我還是很高興，因為我又多了一項技能，以后的路就更好走一些。后來問老師才知道不要求做三維制圖，也不用管缸，馬達等實體如何空間布置，只做系統(tǒng)圖和泵站圖，這才明白，所想與所要求的背道而馳。 元件選型感觸最深，第一次我選擇的元件很多，很雜，在畫裝配圖時，怎么也組合不起來，很是納悶！仔細(xì)觀察油孔布置之后發(fā)現(xiàn)力氏樂的六通徑和油研的六通徑空位置不一樣。第二次選擇，全部選擇力氏樂的電磁換向閥，液控單向閥，單向節(jié)流閥，可是，還是組合不到一起來，除非管式連接，可 是老師要求的是疊加閥，怎么就疊不起來呢？問同學(xué)，又問老師，還是不明白，明明他們都可以疊加起來，為什么我的就不行？思來想去，突然大笑，原來我是一個很爛的月老，非要把普通閥當(dāng)作疊加閥用，能疊起來嗎？第三次，經(jīng)歷元件選型就比較順利。這個過程就像織繭一樣，每一個動作都是在為最后的“房子”增磚添瓦。在老師的指導(dǎo)下，我順利的完成了畢業(yè)設(shè)計。 the speed of an actuator depends on how much oil is pumped into it per unit of time. It is possible to regulate flow with a variable displacement pump, but in many circuits it is more practical to use a fixed displacement pump and regulate flow with a volume control valve. Flow Control Methods There are three basic methods of applying volume control actuator speeds. They are meterin, meterout and bleedoff. MeterIn Circuit In meterin operation, the flow control valve is placed between the pump and actuator. In this way, it controls the amount of fluid going into the actuator. Pump delivery in excess of the Metered amount I diverted to tank over the relief valve. With the flow control valve installed in the cylinder line as shown, flow is controlled in one direction. A check valve must be included in the flow control or placed in parallel with it for return flow. If it is desired to control directional valve. The method is highly accurate. It is used in applications where the load continually resists movement of the actuator, such as raising a vertical cylinder under load or pushing a load at a controlled speed. 24 MeterOut Circuit Meterout control is used where the load might tend to run away. The flow control is located where it will restrict exhaust flow from the actuator. To regulate speed in both directions, the valve is installed in the tank line from the directional valve. More often control is needed in only one direction and it is placed in the line between the actuator and direction valve. Here too a bypass check valve would be required for a rapid return stroke. BleedOff Circuit In a bleedoff arrangement, the flow control is bleed off the supply line from the pump and determines the actuator speed by metering a portion of the pump delivery to tank. The advantage is that the pump operates at the pressure required by the work, since excess fluid returns to tank through the flow control instead of through the relief valve. Its disadvantage is some less of accuracy because the measured flow is to tank39。 operating machinery engineering machinery, construction machinery, agricultural machinery, automobiles, etc.。 civil water projects with flo od control and dam gate devices, bed lifts installations, bridges and other manipulation of institutions。 ship from the deck heavy machinery (winch), the bow doors, bulkhead valve, stern thruster, etc.。 militaryindustrial control devices used in artillery, ship anti rolling devices, aircraft simulation, aircraft retractable landing gear and rudder control devices and other devi ces. A plete hydraulic system consists of five parts, namely, power ponents, the implementation of co mponents, control ponents, auxiliary ponents and hydraulic oil. The role of dynamic ponents of the original motive fluid into mechanical energy to the pressure that the hydraulic system of pumps, it is to power the entire hydraulic system. The structure of the form of hydra ulic pump gears are generally