【正文】 如刀具軌跡進行延伸、縮短或修改等。 3) 銑加工 UG/CAM 銑加工模塊可實現(xiàn)各種類型的銑削加工，包括平面銑、型腔銑、固定軸曲面輪廓銑、可變軸曲面輪廓銑、順序銑、點位加工和螺紋銑等。 煙臺大學畢業(yè)論文 (設(shè)計 ) 9 第三章 液壓 油 缸 液壓缸的作用 液壓缸是液壓系統(tǒng)中 最重要的執(zhí)行元件，它將液壓能轉(zhuǎn)變?yōu)闄C械能，實現(xiàn)直線往復(fù)運動 。 液壓缸的分類 按構(gòu)造形式對液壓缸分類，可分為單作用液壓缸和雙作用液壓缸。無論哪種，都只能利用液壓力實現(xiàn)單向動作，其返回行程是利用活塞桿的自重、負荷和彈簧力等的作用完成的，因此具有能夠節(jié)約動力的優(yōu)點。 （ 2） 雙作 用液壓缸 這種形式的液壓缸，液壓力可實現(xiàn)液壓缸的雙向往復(fù)運動。這種液壓缸有雙活塞桿式和單活塞桿式兩種。 雙作用單活塞桿式液壓缸的工作原理 圖 31 雙作用單活塞桿式液壓缸 煙臺大學畢業(yè)論文 (設(shè)計 ) 10 雙作用單活塞桿式液壓缸如圖 31 所 示。工作時 可以是缸筒 固定，活塞桿驅(qū)動載荷；還可 以是活塞桿固定，缸筒去驅(qū)動載荷。從而完成正、反兩個方向的運動，故稱之為雙作用液壓缸。液壓缸的規(guī)格、品種正日趨齊全，結(jié)構(gòu)也在不斷改進。此外，在船舶、飛機、農(nóng)業(yè)機械、冶金設(shè)備及其他自動化設(shè)備裝置中也大量應(yīng)用 。專業(yè)化生產(chǎn)不僅能提高生產(chǎn)效率、還能提高質(zhì)量、縮短生產(chǎn)周期、降低成本，更重要的是保證性能指標的穩(wěn)定。目前液壓缸 的最大工作壓力已超過 140Mpa。 今年來，國內(nèi)外發(fā)表的不少論文中，研究了液壓缸的穩(wěn)定性、強度和局部應(yīng)力等問題，研究了液壓缸的運動特性和緩沖理論，以及液壓缸的壽命等問題，用有限元法計算液壓缸的強度、重量及成本為目標函數(shù)的優(yōu)化設(shè)計也日益增多。因而，今后有必要進行大量的實驗研究工作，進一步充實并完善液壓缸的設(shè)計理論。 本次設(shè)計應(yīng)用三維建模軟件 UG 對液壓油缸進行建模和運動學仿真，更加形象的理解油缸工作的原理，同時認識到 UG 在同系列的建模軟件中更加強大的功能和智能化操作系統(tǒng)。 本文的重點在于探索如何更為直觀有效的模擬液壓挺柱工作時的實際情況，探索其工作時對車廂的作用，下一步的工作的重點就是改善油缸工作時的性能，從而使車廂在升降時更加穩(wěn)定、快捷、方便。 煙臺大學畢業(yè)論文 (設(shè)計 ) 36 致謝 時光荏苒，歲月如梭，不知不覺間大學四年的時光走到了終點，畢業(yè)后也許很多身影為從我們身邊溜走。 在本次設(shè)計過程中，特別感謝馬國清老師。同時馬老 師淵博的知識， 嚴肅的科學態(tài)度，嚴謹?shù)?治學精神，深深地感染和激勵著我。 論文即將完成，心情十分高興。 通過這次畢業(yè)設(shè)計 所收獲的不僅僅是愈加豐厚的知識，更重要的是在閱讀、實踐中所培養(yǎng)的思維方式、表達能力和廣闊視野。 在此我深深的感謝幫助過我的好朋友， 謹以最樸實的話語致以最崇高的敬意 ，謝謝 你們 。 ll wait in the line for one hour to get a ticket, and another two hours at the site, to only see a tiny bit of the place due to the crowds. Last year, 428 million tourists traveled in China over the weeklong holiday in October. Traveling during this period is a matter that needs thorough preparation. If you are short on time to plan the uping Golden Week it may not be a bad idea to avoid some of the most crowded places for now. There is always a place so fascinating that everyone yearns for. Arxan is a place like this. The beauty of Arxan is everlasting regardless of the changing of four seasons. Bestowed by nature, its spectacular seasonal landscape and mountains are just beyond word. Arxan is a crucial destination for the remended travelling route, China Inner Mongolia Arxan — Hailar — Manzhouli. It is also the joint of the four prairies across the SinoMongolian border, where people gravitate towards the exotic atmosphere mixed with Chinese, Russian, and Mongolia elements. As a historic site for the Yitian Battle, Arxan still embodies the spirit of Genghis Khan. Walking into Arxan, you will be amazed by a kaleidoscope of geous colors all the year round the Spring azaleas blooming red in the snow, the Summer sea wavering blue in the breeze, the Autumn leaves painted in yellow covering volcanic traces, and the Winter woods shining white on the vast alpine snowscape. Hinggan League Arxan city is situated in the far eastern area of Inner Mongolia Autonomous Region. Its full name Haren Arxan means hot holy water in the Mongolian language. Arxan is a tourism city in the northern frontier with a blend of large forest, grand prairies, vast snowfield, heaven lake cluster, thermium, as well as volcanic cluster. It is a rare and 煙臺大學畢業(yè)論文 (設(shè)計 ) 39 unique ecotourism base filled with healthy sunshine, clean air and unspoiled green. Nestled close to the country39。s time for the wild fruits to ripe. The picturesque Arxan in Autumn is indeed a fairyland only exists in a dream that satisfies all your fantasies. If it rains heavily on Saturday night, some elderly Chinese will say it is because Zhinu, or the Weaving Maid, is crying on the day she met her husband Niulang, or the Cowherd, on the Milky Way. Most Chinese remember being told this romantic tragedy when they were children on Qixi, or the Seventh Night Festival, which falls on the seventh day of the seventh lunar month, which is usually in early August. This year it falls on Saturday, August 2. Folklore Story As the story goes, once there was a cowherd, Niulang, who lived with his elder brother and sisterinlaw. But she disliked and abused him, and the boy was forced to leave home with only an old cow for pany. The cow, however, was a former god who had violated imperial rules and was sent to earth in bovine form. One day the cow led Niulang to a lake where fairies took a bath on earth. Among them was Zhinu, the most beautiful fairy and a skilled seamstress. The two fell in love at first sight and were soon married. They had a son and daughter and their happy life was held up as an example for hundreds of years in China. Yet in the eyes of the Jade Emperor, the Supreme Deity in Taoism, marriage between a mortal and fairy was strictly forbidden. He ordered the heaven troop to catch Zhinu back. Niulang grew desperate when he discovered Zhinu had been taken back to heaven. Driven by Niulang39。 Festival. In this day, girls will throw a sewing needle into a bowl full of water on the night of Qixi as a test of embroidery skills. If the needle floats on top of the water instead of sinking, it proves the girl is a skilled embroiders. Single women also pray for finding a good husband in the future. And the newly married women pray to bee pregnant quickly. Tradition transformed The love story of Niulang and Zhinu, and the Qixi Festival have been handed down for generations. Yet these ancient traditions and customs are slowly dying out. Many modern Chinese, particularly youngsters, seem to know more about St Valentine39。s Day. More and more young Chinese people begin to celebrate this day in a very similar way as that in western countries. Fewer people than ever will gaze at the heavens on Saturday to pick out the two stars shining bright on either side of the Milky Way, that is, if people even know on which day Qixi falls. There are ready reminders dotted about, in the form of big ads saying Sales on Chinese Valentine39