四輥逆軋機設計畢業論文-資料下載頁

　　

【正文】 低、使用壽命長、允許傾角大等優點。，提高了傳動質量；電機采用直流變頻調速，具有良好的調速性能，其調速范圍寬，平滑性好，響應速度快，效率高大大提高軋制質量，加快反向速度。致謝畢業設計作為大學的最后一課，教會了我很多以前在課堂上所沒有學到的東西。將我們的所學用到了實際問題上。在整個設計過程中，得到了很多老師的幫助，學院老師嚴謹的治學態度讓我受益匪淺。我非常感謝我的指導教師徐澤寧教授，每當我到困難時，徐老師都能在百忙中抽出時間為我悉心講解。感謝同組人員在整個設計過程中的幫助；感謝鞍鋼集團冷軋廠、寶鋼股份有限公司特鋼廠、鋼股份有限公司熱軋廠的領導和工人師傅門，為我們畢業實習提供的幫助；感謝圖書館計算機機房為我查閱資料提供的方便。正是有了大家的幫助我才能利完成畢業設計，謹此致以最誠摯的謝意。參 考 文 獻[1] (第三版).北京：冶金工業出版社，2006[2] ：機械工業出版社，1976[3] （第一版）. 北京：機械工業出版社，1992[4] （第一版）. 北京：機械工業出版社，1992[5] （第一版）. 北京：機械工業出版社，1992[6] （第一版）. 北京：機械工業出版社，1992[7] （第一版）. 北京：機械工業出版社，1992[8] 鞏云鵬， 田萬祿， 黃秋波，. 沈陽：東北大學出版社，2000[9] 濮良貴，（第七版）. 北京：高等教育出版社，2005[10] . 北京：機械工業出版社，1983[11] 張建宇，高立新，工會剛，等. ， 2005，22（2）付：外文翻譯 電火花加工 電火花加工法對加工超韌性的導電材料（如新的太空合金）特別有價值。這些金屬很難用常規方法加工，用常規的切削刀具不可能加工極其復雜的形狀，電火花加工使之變得相對簡單了。在金屬切削工業中，這種加工方法正不斷尋找新的應用領域。塑料工業已廣泛使用這種方法，如在鋼制模具上加工幾乎是任何形狀的模腔。 電火花加工法是一種受控制的金屬切削技術，它使用電火花切除（侵蝕）工件上的多余金屬，工件在切削后的形狀與刀具（電極）相反。切削刀具用導電材料（通常是碳）制造。電極形狀與所需型腔想匹配。工件與電極都浸在不導電的液體里，這種液體通常是輕潤滑油。它應當是點的不良導體或絕緣體。 ~（~）的間隙，以阻止他們相互接觸。頻率為20000Hz左右的低電壓大電流的直流電加到電極上，這些電脈沖引起火花，跳過電極與工件的見的不導電的液體間隙。在火花沖擊的局部區域，產生了大量的熱量，金屬融化了，從工件表面噴出融化金屬的小粒子。不斷循環著的不導電的液體，將侵蝕下來的金屬粒子帶走，同時也有助于驅散火花產生的熱量。 在最近幾年，電火花加工的主要進步是降低了它加工后的表面粗糙度。用低的金屬切除率時，表面粗糙度可達2—4vin.(—)。用高的金屬切除率[如高達15in3/h()]時，表面粗糙度為1000vin.(25vm)。 需要的表面粗糙度的類型，決定了能使用的安培數,電容,頻率和電壓值?？焖偾谐饘伲ù智邢鳎r，用大電流,低頻率,高電容和最小的間隙電壓。緩慢切除金屬（精切削）和需獲得高的表面光潔度時，用小電流,高頻率,低電容和最高的間隙電壓。 與常規機加工方法相比，電火花加工有許多優點。 1 . 不論硬度高低，只要是導電材料都能對其進行切削。對用常規方法極難切削的硬質合金和超韌性的太空合金，電火化加工特別有價值。 2 . 工件可在淬火狀態下加工，因克服了由淬火引起的變形問題。 3 . 很容易將斷在工件中的絲錐和鉆頭除。 4 . 由于刀具（電極）從未與工件接觸過，故工件中不會產生應力。 5 . 加工出的零件無毛刺。 6 . 薄而脆的工件很容易加工，且無毛刺。 7 . 對許多類型的工件，一般不需第二次精加工。 8 .隨著金屬的切除，伺服機構使電極自動向工件進給。 9 .一個人可同時操作幾臺電火花加工機床。 ，加工出常規方法不可能加工出來的極復雜的形狀。 。，在陰模板上復制其形狀，并留有必須的間隙。Electrical discharge machiningElectrical discharge machining has proved especially valuable in the machining of supertough, electrically conductive materials such as the new spaceage alloys. These metals would have been difficult to machine by conventional methods, but EDM has made it relatively simple to machine intricate shapes that would be impossible to produce with conventional cutting tools. This machining process is continually finding further applications in the metalcutting industry. It is being used extensively in the plastic industry to produce cavities of almost any shape in the steel molds. Electrical discharge machining is a controlled metal removal technique whereby an electric spark is used to cut (erode) the workpiece, which takes a shape opposite to that of the cutting tool or electrode. The cutting tool (electrode) is made from electrically conductive material, usually carbon. The electrode, made to the shape of the cavity required, and the workpiece are both submerged in a dielectric fluid, which is generally a light lubricating oil. This dielectric fluid should be a nonconductor (or poor conductor) of electricity. A servo mechanism maintains a gap of about to in. ( to mm) between the electrode and the work, preventing them from ing into contact with each other. A direct current of low voltage and high amperage is delivered to the electrode at the rate of approximately 20 000 hertz (Hz). These electrical energy impulses bee sparks which jump the dielectric fluid. Intense heat is created in the localized area of the park impact, the metal melts and a small particle of molten metal is expelled from the surface of the workpiece . The dielectric fluid, which is constantly being circulated, carries away the eroded particles of metal and also assists in dissipating the heat caused by the spark.In the last few years, major advances have been made with regard to the surface finishes that can be produced. With the low metal removal rates, surface finishes of 2 to 4 um. ( to ) are possible. With high metal removal rates finishes of 1 000uin. (25um) are produced.The type of finish required determines the number of amperes which can be used, the capacitance, frequency, and the voltage setting. For fast metal removal (roughing cuts), high amperage, low frequency, high capacitance, and minimum gap voltage are required. For slow metal removal (finish cut) and good surface finish, low amperage, high frequency, low capacitance, and the highest gap voltage are required.Electrical discharge machining has many advantages over conventional machining processes.1. Any material that is electrically conductive can be cut, regardless of its hardness. It is especially valuable for cemented carbides and the new supertough spaceage alloys that are extremely difficult to cut by conventional means.2. Work can be machined in a hardened state, thereby overing the deformation caused by the hardening process.3. Broken taps or drills can readily be removed from workpieces. 4. It does not create stresses in the work material since the tool (electrode) never es in contact with the work.5. The process is burrfree.6. Thin, fragile sections can be easily machined without deforming.7. Secondary finishing operations are generally eliminated for many types of work.8. The process is automatic in that the servomechanism advances the electrode into the work as the metal is removed.9. One person can operate several EDM machines at one time.10. Intricate shapes, impossible to produce by conventional means, are cut out of a solid with relative ease.11. Better dies and molds can be produced at lower costs.12. A die punch can be used as the electrode to reproduce its shape in the matching die plate, plete with the necessary clearance.