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deploy this chute successfully, he will have to slow to 172 mph (277 kph). He will have a reserve parachute that will open automatically if he loses consciousness at mach speeds. Even if everything goes as planned, it won39。 Baumgartner the disappointing news: Mission aborted. r plays an important role in this mission. Starting at the ground, conditions have to be very calm winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule attached, will move through the lower level of the atmosphere (the troposphere) where our daytoday weather lives. It will climb higher than the tip of Mount Everest ( miles/ kilometers), drifting even higher than the cruising altitude of mercial airliners ( miles/ kilometers) and into the stratosphere. As he crosses the boundary layer (called the tropopause),e can expect a lot of turbulence. The supersonic descent could happen as early as Sunda. The weatheThe balloon will slowly drift to the edge of space at 120,000 feet ( Then, I would assume, he will slowly step out onto something resembling an Olympic diving platform. Below, the Earth bees the concrete bottom of a swimming pool that he wants to land on, but not too hard. Still, he39。 From the corner at the beginning of deep friendship。嫌惡過(guò)自己的怯懦,最終卻發(fā)現(xiàn)有很多 緣分 ,有很多錯(cuò)過(guò),好像冥冥之中真的已經(jīng)注定。 A person39。 Then in high school, think don39。二十年的人生軌跡深深淺淺,突然就感覺到有些事情,非做不可了。s plaint. In a statement the Russian side added: We found no racist insults from fans of CSKA. Age has reached the end of the beginning of a word. May be guilty in his seems to passing a lot of different life became the appearance of the same day。s about how he felt and I would like to speak to him first to find out what his experience was. Uefa has opened disciplinary proceedings against CSKA for the racist behaviour of their fans during City39。re clear about the terms of the agreement. It might be best to get advice from an experienced adviser, for example, at a Citizens Advice Bureau. To find your nearest CAB, including those that give advice by , click on nearest CAB. For more information about making a claim to an employment tribunal, see Employment tribunals. The (lack of) air up there Watch mCayman Islandsbased Webb, the head of Fifa39。 指導(dǎo)教師: 院長(zhǎng)簽字: 年 月 日 g an employment tribunal claim Employment tribunals sort out disagreements between employers and employees. You may need to make a claim to an employment tribunal if: ? you don39。 主要技術(shù)參數(shù): 工作循環(huán):工件夾緊→左、右動(dòng)力部件快進(jìn)→左、右動(dòng)力部件工進(jìn)→左動(dòng)力部件快退,右動(dòng)力部件繼續(xù)工進(jìn)→左動(dòng)力部件停止,右動(dòng)力部件快退→左右動(dòng)力部件皆停止,工 件松開。 2. 液壓系統(tǒng)原理圖。還要感謝孫老師、郭老師他們給了我寶貴的意見,細(xì)心的講解了設(shè)計(jì)的格式等重要內(nèi)容。通過(guò)這次設(shè)計(jì)我不僅僅對(duì)液壓方面的知識(shí)有了更多的了解,而且機(jī)械制造和制圖的知識(shí)也有了拓展,更重要的是它大大提高了我的自學(xué)能力及分析問(wèn)題和解決問(wèn)題的能力。 致 謝 隨著歷時(shí)半年的畢業(yè)設(shè)計(jì)的即將結(jié)束 ,我的大學(xué)生活也將劃上完滿的句號(hào)。在閥塊的設(shè)計(jì)方面,由于資料的欠缺,國(guó)內(nèi)現(xiàn)有設(shè)計(jì)方法的限制。由于本系統(tǒng)壓力不高,屬于中壓系統(tǒng),根據(jù)經(jīng)驗(yàn)確定各通油孔道間的最小間隔尺寸為 5mm。公共壓力油和回油孔根據(jù)經(jīng)驗(yàn)和流量由《機(jī)械設(shè)計(jì)手冊(cè)》表功 31 選Ф 10mm孔。把四個(gè)閥放在同一個(gè)水平面上以簡(jiǎn)化油路,使集成塊尺寸減小。在底座右側(cè)裝兩個(gè)焊接式管接頭與液壓泵的兩個(gè)壓力油口相連,在底座上打 3 個(gè)孔,一個(gè)孔是公共回油孔 0 通油箱。 工進(jìn)時(shí)液壓泵的輸入功率如前面計(jì)算 P1=1201W 工進(jìn)時(shí)液壓缸的輸入功率 P2=FV=( 16821 1/60) W= 系統(tǒng)總的發(fā)熱功率φ為 φ =2( P1 P2) =[2( ) ]W= 已知:油箱容積 V=240L= 按《液壓與氣壓傳動(dòng)》式( 819)油箱近似散熱面積 A為 223 23 2 mmVA ??? 假定通風(fēng)良好,取油箱散熱系數(shù) G=15 103KW/(㎡℃) 則利用《液壓與氣壓傳動(dòng)》式( 818)可得油液溫升為 33 ??? ??????GAT ? ℃ 設(shè)環(huán)境溫度 T2=20℃,則熱平衡溫度為 T1=T2+Δ T=20+ =℃≤ [T1]=80℃ 所以油箱散熱基本可達(dá)到要求。 1)確定油液的流動(dòng)狀態(tài) 由《液壓與氣壓傳動(dòng)》式( 130)經(jīng)單位換算為 44 ???? ?? qvd 式中 v— 平均流速( m/s) d— 油管內(nèi)徑( m) ν — 油的運(yùn)動(dòng)粘度(㎝ 2/s) q— 通過(guò)的流量( m3/s) 則進(jìn)油路中液流的雷諾數(shù)為 4331 ????? ??? ?? 回油路中液流的雷諾數(shù)為 Re2= 33 ???? ???? 由上可知,進(jìn)油路中的流動(dòng)是層流。 因快退時(shí),液壓缸無(wú)桿腔的回油路是進(jìn)油路的兩倍,其壓力損失比快進(jìn)時(shí) 要大,因此必須計(jì)算快退時(shí)的進(jìn)油路與回油路壓力損失,以便確定泵 2 的卸載壓力。 油箱容積的確定 中壓系統(tǒng)的油箱容積一般取液壓系統(tǒng)額定流量的 57倍。根據(jù)《機(jī)械零件設(shè)計(jì)手冊(cè)》表 331選φ 14 3mm的 15號(hào)冷拔無(wú)縫鋼管。液壓泵油管的選擇根據(jù)泵的口徑選取。額定壓力 。查表《機(jī)械零件設(shè)計(jì)手冊(cè)》表 352選用型號(hào) WU40 180J型號(hào)的過(guò)濾器。 調(diào)圍 13Mpa,定流量20min。查表《機(jī)械設(shè)計(jì)手冊(cè)》 32321 選用 4WE5C600/OF型號(hào)的濕式電磁換向閥。調(diào)壓范圍 37Mpa 額定流量 20L/min。查表《機(jī)械零件設(shè)計(jì)手冊(cè)》 3211 選用 YE12HD10B 型號(hào)電磁溢流閥。 ( 7)卸荷閥: 最大通過(guò)流量 10L/min,所受壓力為 105Pa。查表《機(jī)械零件設(shè)計(jì)手冊(cè)》 3226 選用 X3FB10F型號(hào)順序閥。查表選用型號(hào) DFB10K1單向閥。 選擇液壓閥 根據(jù)液壓閥在系統(tǒng)中的最高工作壓力與通 過(guò)的最大流量,可選出這些元件的型號(hào)及規(guī)格。 ( 1) 差動(dòng)快進(jìn)時(shí),泵 2的出口壓力油經(jīng)單向閥 8 后與泵 1 匯合,然后經(jīng)單向閥 18,三位五通閥 3,行程閥 5進(jìn)入液壓缸大腔,大腔的壓力 p1=pj= 105Pa,泵 2 出口到泵 1 出口的壓力損失Δp2= 105Pa。 由表 3 可知工進(jìn)階段液壓缸工作壓力最大,若取進(jìn)油路壓力損失∑Δ p=5 105Pa,則液壓泵調(diào)節(jié)工作壓力 Pp=p1+∑Δ p=( +5) 105Pa= 105Pa 因此泵的額定壓力可取 Pr≥ 105Pa=53 105Pa 由表 3 可知,工進(jìn)時(shí)所需的最大流量是 ,設(shè)溢流閥最小溢流量為 ,加之減壓閥工作時(shí)的正常泄出(一般為),則小流量泵的流量應(yīng)為 qp1≥( + ) L/min=( ) L/min= L/min 快進(jìn)快退時(shí),液 壓缸所需的最大流量是 L/min,則泵總流量為 qp= L/min= L/min 即大流量泵的流量為 qp≥ qp=( ) L/min 根據(jù)上面計(jì)算的壓力和流量,查《機(jī)械零件設(shè)計(jì)手冊(cè)》表 3059選用 YB110/10型的雙聯(lián)葉片泵,該泵的額定壓力為 。 為便于觀察和調(diào)整壓力,在液壓泵的出口處設(shè)置測(cè)壓點(diǎn),并設(shè)置多點(diǎn)壓力表開關(guān)。先定位后夾緊的順序動(dòng)作可由順序閥來(lái)完成。工進(jìn)時(shí)只有高壓小流量泵供油,大泵可卸荷。由于液壓缸采用了差動(dòng)連接,電磁換向閥宜用三位五通電磁閥。另外采用液控順序閥與單向閥來(lái)切斷差動(dòng)回路。這種回路的效率較高,且能實(shí)現(xiàn)比最大工進(jìn)速度大得多的快速運(yùn)動(dòng),在機(jī)床上得到了廣泛的應(yīng)用。 經(jīng)比較選用雙泵供油形式更為合適。開式系統(tǒng)的缺點(diǎn)是抗污染能力差,而且油箱較大。 計(jì)算液壓缸各工作階段的工作壓力、流量和功率 根據(jù)液壓缸的負(fù)載圖和速度