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本科畢業(yè)設(shè)計(jì) 論文 開題報(bào)告 學(xué)生姓名 曹 鑫 學(xué) 號(hào) 09B06070319 指導(dǎo)教師 吳元生 學(xué) 院 機(jī)電學(xué)院 專 業(yè) 機(jī)械設(shè)計(jì)制造及其自動(dòng)化 交稿日期 2012 12 23 教務(wù)處制 一 開題報(bào)告 畢業(yè)設(shè)計(jì) 論文 題目 教學(xué)液壓試驗(yàn)臺(tái)基本實(shí)驗(yàn)回路的設(shè)計(jì) 課題背景和意義 液壓實(shí)驗(yàn)臺(tái)是液壓實(shí)驗(yàn)室上世紀(jì) 80 年代初期生產(chǎn)的實(shí)驗(yàn)設(shè)備 類似早期的液壓設(shè)備試驗(yàn)系統(tǒng)大部 分按照 傳感器 模擬二次儀表 的模式組成 在試驗(yàn)過程中 一般由模擬記錄儀器在紙上記錄試驗(yàn)曲 線或由試驗(yàn)人員讀取并記錄試驗(yàn)數(shù)據(jù) 然后試驗(yàn)人員根據(jù)試驗(yàn)曲線和數(shù)據(jù)手工處理 得到設(shè)備的性能 教學(xué)實(shí)驗(yàn)臺(tái)利用壓力表測(cè)量液壓系統(tǒng)中某一給定點(diǎn)的壓力 表盤指針?biāo)甘镜目潭葘?duì)應(yīng)某一壓力值 由于小幅度波動(dòng)的壓力振擺和隨時(shí)間而漂移的壓力偏移值很難通過壓力表指針反映出來 有限的刻度 格數(shù)使讀數(shù)依賴于實(shí)驗(yàn)操作者的目測(cè)習(xí)慣 從而使測(cè)量精度得不到保證 原實(shí)驗(yàn)使用動(dòng)態(tài)應(yīng)變儀 光 線示波器 感光紙記錄閥從一種穩(wěn)定工作狀態(tài)到另一穩(wěn)定工作狀態(tài)的過渡過程曲線 操作過程復(fù)雜繁 瑣 對(duì)液壓系統(tǒng)加載一卸荷時(shí)的被控壓力隨時(shí)間變化所反映的動(dòng)態(tài)特性參數(shù)如動(dòng)態(tài)超調(diào) 只能做出定 性分析 實(shí)驗(yàn)臺(tái)利用橢圓齒輪流量計(jì)測(cè)量流量 由于指針指示的刻度值是通過流量計(jì)的流體體積總量 因此實(shí)驗(yàn)時(shí)需利用秒表觀測(cè)流量計(jì)指針每分鐘走過的格數(shù)來計(jì)算此時(shí)的流量值 當(dāng)流量較小時(shí) 如測(cè) 量溢流閥的溢流量時(shí) 齒輪的轉(zhuǎn)速很低 泄漏量較大 致使誤差很大 為測(cè)量液壓缸活塞桿在不同負(fù) 載條件下的運(yùn)動(dòng)速度 實(shí)驗(yàn)時(shí)首先測(cè)出活塞桿的總行程 再利用秒表測(cè)量活塞桿走完這段行程所用時(shí) 間 兩者相除得到活塞桿的運(yùn)動(dòng)速度 這種方法很難客觀準(zhǔn)確地反映液壓缸活塞桿帶負(fù)載工作時(shí)的速 度特性 對(duì)于像閥門快開 快關(guān)這樣的快速性試驗(yàn) 往往是通過人的經(jīng)驗(yàn)來判斷設(shè)備是否工作正常 顯然用這種試驗(yàn)方法得到的結(jié)果帶有嚴(yán)重的人為誤差 效率低 精度差 而且試驗(yàn)過程操作繁瑣 分 析不方便 因此 對(duì)現(xiàn)有的教學(xué)實(shí)驗(yàn)臺(tái)進(jìn)行必須進(jìn)行更新?lián)Q代才能滿足實(shí)際需求 隨著液壓技術(shù) 控制理論 微型計(jì)算機(jī) 測(cè)量測(cè)試技術(shù) 數(shù)字信息處理 可靠技術(shù)的發(fā)展 新的 液壓試驗(yàn)臺(tái)已朝著高速 高效 智能化 多功能化的液壓計(jì)算機(jī)輔助測(cè)試 CAT 方向發(fā)展 早期 傳 感器 模擬二次儀表 的模式組成液壓設(shè)備試驗(yàn)系統(tǒng)已停止使用 基于虛擬儀器技術(shù)的液壓 CAT 系統(tǒng)廣 泛應(yīng)用于新的液壓實(shí)驗(yàn)臺(tái)制造及應(yīng)用 采用的計(jì)算方法有平均值濾波法 中值濾波算法 新型 PID 算 法等 采用有 vB6 等應(yīng)用軟件開發(fā)液壓 CAT 實(shí)驗(yàn)軟件 由于原有設(shè)備的陳舊或故障面積太大 僅法相 用 MCS 51 單片機(jī)技術(shù)對(duì)舊式液壓實(shí)驗(yàn)臺(tái)重新開發(fā)與利用 因此 很少發(fā)現(xiàn)采用液壓計(jì)算機(jī)輔助測(cè)試 CAT 對(duì)舊式液壓實(shí)驗(yàn)臺(tái)重新開發(fā)與利用 對(duì)舊式液壓試驗(yàn)臺(tái)重新開發(fā)與利用有一定的推廣應(yīng)用價(jià)值 研究的主要內(nèi)容 一 課題主要內(nèi)容 1 在了解液壓實(shí)驗(yàn)臺(tái)結(jié)構(gòu)的基礎(chǔ)上 根據(jù)液壓實(shí)驗(yàn)臺(tái)的功能要求 給出液壓實(shí)驗(yàn)臺(tái)系統(tǒng)原理的設(shè)計(jì) 及基本實(shí)驗(yàn)回路的設(shè)計(jì) 2 根據(jù)設(shè)計(jì)好的液壓系統(tǒng) 設(shè)計(jì)出基本的實(shí)驗(yàn)回路 3 詳細(xì)分析系統(tǒng)的輸入輸出 完成液壓實(shí)驗(yàn)臺(tái)的硬件的選取 4 對(duì)液壓實(shí)驗(yàn)臺(tái)的液壓控制回路進(jìn)行設(shè)計(jì) 可以使用戶更加方便的了解實(shí)驗(yàn)臺(tái)的運(yùn)行狀況 5 用三維軟件繪制所有圖紙 二 課題主要要求 1 了解液壓試驗(yàn)臺(tái)的應(yīng)用和發(fā)展 2 對(duì)液壓試驗(yàn)臺(tái)的結(jié)構(gòu) 工作原理 特點(diǎn)有一個(gè)非常深入的了解 3 在掌握機(jī)械設(shè)計(jì) 機(jī)械制圖 液壓傳動(dòng)課的基本知識(shí)基礎(chǔ)上 學(xué)會(huì)查閱有關(guān)國(guó)內(nèi)外有關(guān)設(shè)計(jì)資料 進(jìn)行有關(guān)設(shè)計(jì) 4 液壓試驗(yàn)臺(tái)的液壓元件 系統(tǒng)管路 油箱等元件的選用 5 設(shè)計(jì)液壓試驗(yàn)臺(tái)的液壓系統(tǒng) 6 能夠設(shè)計(jì)常用的基本回路實(shí)驗(yàn) 7 繪制所有圖紙 研究方法 或技術(shù)路線 1 查閱資料文獻(xiàn) 查找設(shè)計(jì)所需的資料 資料的內(nèi)容要有深度 要具有參考意義 2 熟練掌握設(shè)計(jì)所需的內(nèi)容 復(fù)習(xí)以前所學(xué)設(shè)計(jì)有關(guān)的專業(yè)知識(shí) 并熟練的運(yùn)用到設(shè)計(jì)中去 還要學(xué)習(xí)一些設(shè)計(jì)中所用到的其它 方面的知識(shí) 通過查閱資料文獻(xiàn) 解決發(fā)現(xiàn)的問題 3 設(shè)計(jì)內(nèi)容 1 完成綜合液壓實(shí)驗(yàn)臺(tái)系統(tǒng)設(shè)計(jì) 2 完成綜合液壓實(shí)驗(yàn)臺(tái)基本實(shí)驗(yàn)回路的設(shè)計(jì) 3 具體能夠完成以下試驗(yàn) 1 液壓回路的溢流控制 2 液壓回路的節(jié)流控制 3 液壓油缸伸出與收回?zé)o 級(jí)調(diào)速控制控制 4 單活塞液壓缸的差動(dòng)連接控制 5 液壓馬達(dá)的正 反轉(zhuǎn)無級(jí)調(diào)節(jié)控制 6 液壓系統(tǒng)的無級(jí) 調(diào)壓等試驗(yàn) 4 具體設(shè)計(jì)步驟 經(jīng)參閱文獻(xiàn)資料以及對(duì)本校液壓試驗(yàn)臺(tái)觀察研究 初步提出以下方案 1 對(duì)現(xiàn)有液壓試驗(yàn)儀器進(jìn)行整合 采用模塊化設(shè)計(jì) 使其集中到一臺(tái)儀器上操作 安裝多個(gè)電磁閥 以實(shí)現(xiàn)不同液壓回路的控制 2 對(duì)于額定壓力為 6 3MP 進(jìn)行試驗(yàn)臺(tái)的系統(tǒng)設(shè)計(jì) 3 對(duì)于額定壓力對(duì)液壓元件進(jìn)行選擇 4 基本實(shí)驗(yàn)回路的設(shè)計(jì) 5 設(shè)計(jì)說明書 預(yù)期結(jié)果 1 結(jié)合機(jī)械設(shè)計(jì) 機(jī)械制圖 液壓傳動(dòng)課的學(xué)習(xí) 設(shè)計(jì)液壓系統(tǒng)原理圖 2 用 CAD 畫出各部件圖 零件圖和總圖 3 設(shè)計(jì)計(jì)算說明書一份 進(jìn)度計(jì)劃 2012 年 12 月 6 日 2012 年 12 月 12 日 尋找資料 查閱文獻(xiàn) 文獻(xiàn)翻譯 2012 年 12 月 13 日 2012 年 12 月 23 日 開題報(bào)告準(zhǔn)備 2012 年 12 月 24 日 2013 年 1 月 11 日 液壓試驗(yàn)臺(tái)的工作原理和機(jī)械結(jié)構(gòu)分析 2013 年 1 月 12 日 2013 年 1 月 31 日 設(shè)計(jì)液壓試驗(yàn)臺(tái)的液壓系統(tǒng)原理圖 2013 年 2 月 1 日 2013 年 3 月 1 日 設(shè)計(jì)液壓基本實(shí)驗(yàn)回路 2013 年 3 月 2 日 2013 年 4 月 1 日 繪制所有圖紙 2013 年 4 月 2 日 2013 年 4 月 14 日 編寫設(shè)計(jì)說明書 2013 年 4 月 15 日 論文遞交 2013 年 4 月 30 日 論文內(nèi)審和外審 2013 年 5 月 論文答辯 指導(dǎo)教師意見 指導(dǎo)教師簽名 年 月 日 系部意見 審 查 結(jié) 果 同 意 不 同 意 系主任簽名 年 月 日 二 閱讀文獻(xiàn)目錄 序號(hào) 作者 文獻(xiàn)名 文獻(xiàn)出處 文獻(xiàn)發(fā)表時(shí)間 1 張福臣 液壓與氣壓傳動(dòng) M 北京 機(jī)械工業(yè)出版社 2006 1 2 吳杰 多功能液壓元件綜合實(shí)驗(yàn)臺(tái) 的設(shè)計(jì) J 機(jī)械工程師 2008 4 3 鄧克 多功能綜合液壓實(shí)驗(yàn)臺(tái)的研 制 J 液壓與氣動(dòng) 2008 4 4 張志偉 液壓綜合教學(xué)實(shí)驗(yàn)臺(tái)在 液 壓傳動(dòng) 實(shí)驗(yàn)教學(xué) J 中的 應(yīng)用 裝備制造技術(shù) 2007 1 5 卞和營(yíng) 李增權(quán) 李宏 偉 PLC 在液壓回路實(shí)驗(yàn)臺(tái)控制 中的應(yīng)用 J 內(nèi)江科技 2007 12 6 孫小權(quán) 何喜玲 基于 PLC 的液壓實(shí)驗(yàn)臺(tái)控制系統(tǒng)改造設(shè)計(jì) J 應(yīng)用科技 2006 11 7 鄭勝利 可拆式液壓實(shí)驗(yàn)臺(tái)的電氣控 制系統(tǒng)改造 J 煤礦機(jī)械 2006 11 8 王吉芳 陳秀梅 多功能液壓教學(xué)實(shí)驗(yàn)臺(tái)設(shè)計(jì) J 液壓與氣動(dòng) 2003 1 9 王文深 PLC 控制的多功能液壓教學(xué)綜合實(shí)驗(yàn)臺(tái)的研制 J 液壓與氣動(dòng) 2003 10 10 田玲 楊連發(fā) PLC 控制液壓回路快速組合 實(shí)驗(yàn)臺(tái)設(shè)計(jì) J 機(jī)械 2003 1 11 瞿愛琴 王同建 呂景 忠 快速插接任意組合式液壓與 氣壓傳動(dòng)綜合教學(xué)實(shí) J 驗(yàn)臺(tái)的研 制 實(shí)驗(yàn)技術(shù)與管理 2003 6 12 陳為國(guó) 丁敘生 李堯 忠 多功能液壓教學(xué)實(shí)驗(yàn)臺(tái)執(zhí)行 裝置的設(shè)計(jì) J 機(jī)床與液壓 2003 6 13 陸寶春 張衛(wèi) 路建萍 電氣與 PC 控制技術(shù) M 南京 南京理工大學(xué)出 版社 2000 14 王積偉 章宏甲 等 液壓與氣壓傳動(dòng) M 第二版 北京 機(jī)械工業(yè)出版社 2005 15 李賢焱 液壓傳動(dòng)與控制 M 重慶大學(xué)出版社 1993 16 王占林 近代液壓控制 M 機(jī)械工業(yè)出版社 1997 8 17 王鑫 等 液壓設(shè)計(jì)手冊(cè) M 機(jī)械工業(yè)出版社 1996 18 賈銘新 液壓傳動(dòng)與控制 M 第二版 國(guó)防工業(yè)出版 社 2001 三 文獻(xiàn)綜述 注意 學(xué)生閱讀文獻(xiàn)后 必須寫出 3000 字左右的綜述 作為開題內(nèi)容之一 可增頁 一 液壓傳動(dòng)的發(fā)展及研究對(duì)象 液壓傳動(dòng)技術(shù)的發(fā)展可追朔到 17 世紀(jì)帕斯卡提出了著名的帕斯卡定律 開始奠定了流體靜壓傳 動(dòng)的理論基礎(chǔ) 從 18 世紀(jì)末英國(guó)制成了世界上第一臺(tái)水壓機(jī)算起 已有近 300 年的歷史 但真正的發(fā) 展只是在第二次世界大戰(zhàn)后 液壓技術(shù)由軍用工業(yè)迅速轉(zhuǎn)向民用工業(yè) 而我國(guó)液壓工業(yè)只經(jīng)過 40 余年 的發(fā)展 就已經(jīng)形成門類齊全 有一定的技術(shù)水平并初具規(guī)模的生產(chǎn)科研體系 其生產(chǎn)的液壓產(chǎn)品廣 泛應(yīng)用于工業(yè) 農(nóng)業(yè)和國(guó)防等各個(gè)部門 近 20 年來我國(guó)液壓工業(yè)通過引進(jìn)先進(jìn)技術(shù) 科研攻關(guān) 產(chǎn) 品應(yīng)用技術(shù)飛快發(fā)展 設(shè)計(jì)生產(chǎn)了許多新型的液壓元件 此外通過計(jì)算機(jī)輔助技術(shù) CAD 計(jì)算機(jī)輔助 測(cè)試 CAT 污染控制 故障診斷 機(jī)電一體化等方面研究成果的應(yīng)用 液壓技術(shù)水平得到了很大的提 高 當(dāng)前液壓技術(shù)正向著高效率 高精度 高性能等方向發(fā)展 液壓元件向著體積小 重量輕 微型 化和集成化 易維修的方向發(fā)展 因此急需加速人才培養(yǎng)和技術(shù)創(chuàng)新 使我國(guó)液壓工業(yè)盡早達(dá)到世界 先進(jìn)水平 液壓傳動(dòng)技術(shù)的發(fā)展旨在研究液壓系統(tǒng)各類元件結(jié)構(gòu) 作用 工作原理 應(yīng)用方法以及組 成液壓系統(tǒng)的特點(diǎn) 人們經(jīng)過理論與實(shí)踐的有機(jī)結(jié)合 能夠很快的掌握液壓傳動(dòng)設(shè)備的安裝 調(diào)試 維護(hù)及操作 由于液壓技術(shù)廣泛應(yīng)用了高技術(shù)成果 如自動(dòng)控制技術(shù) 計(jì)算機(jī)技術(shù) 微電子技術(shù) 磨擦磨損技 術(shù) 可靠性技術(shù)及新工藝和新材料 使傳統(tǒng)技術(shù)有了新的發(fā)展 也使液壓系統(tǒng)和元件的質(zhì)量 水平有 一定的提高 盡管如此 走向二十一世紀(jì)的液壓技術(shù)不可能有驚人的技術(shù)突破 應(yīng)當(dāng)主要靠現(xiàn)有技術(shù) 的改進(jìn)和擴(kuò)展 不斷擴(kuò)大其應(yīng)用領(lǐng)域以滿足未來的要求 綜合國(guó)內(nèi)外專家的意見 其主要的發(fā)展趨勢(shì) 將集中在以下幾個(gè)方面 1 減少能耗 充分利用能量 液壓技術(shù)在將機(jī)械能轉(zhuǎn)換成壓力能及反轉(zhuǎn)換方面 已取得很大進(jìn)展 但一直存在能量損耗 主要 反映在系統(tǒng)的容積損失和機(jī)械損失上 如果全部壓力能都能得到充分利用 則將使能量轉(zhuǎn)換過程的效 率得到顯著提高 為減少壓力能的損失 必須解決下面幾個(gè)問題 減少元件和系統(tǒng)的內(nèi)部壓力損失 以減少功率損失 主要表現(xiàn)在改進(jìn)元件內(nèi)部流道的壓力損失 采用集成化回路和鑄造流道 可減少管道 損失 同時(shí)還可減少漏油損失 減少或消除系統(tǒng)的節(jié)流損失 盡量減少非安全需要的溢流量 避免采用節(jié)流系統(tǒng)來調(diào)節(jié)流量和壓力 采用靜壓技術(shù) 新型密封材料 減少磨擦損失 發(fā)展小型化 輕量化 復(fù)合化 廣泛發(fā)展 3 通徑 4 通徑電磁閥以及低功率電磁閥 改善液壓系統(tǒng)性能 采用負(fù)荷傳感系統(tǒng) 二次調(diào)節(jié)系統(tǒng)和采用蓄能器回路 為及時(shí)維護(hù)液壓系統(tǒng) 防止污染對(duì)系統(tǒng)壽命和可靠性造成影響 必須發(fā)展新的污染檢測(cè)方法 對(duì)污 染進(jìn)行在線測(cè)量 要及時(shí)調(diào)整 不允許滯后 以免由于處理不及時(shí)而造成損失 2 主動(dòng)維護(hù) 液壓系統(tǒng)維護(hù)已從過去簡(jiǎn)單的故障拆修 發(fā)展到故障預(yù)測(cè) 即發(fā)現(xiàn)故障苗頭時(shí) 預(yù)先進(jìn)行維修 清除故障隱患 避免設(shè)備惡性事故的發(fā)展 要實(shí)現(xiàn)主動(dòng)維護(hù)技術(shù)必須要加強(qiáng)液壓系統(tǒng)故障診斷方法的 研究 當(dāng)前 憑有經(jīng)驗(yàn)的維修技術(shù)人員的感宮和經(jīng)驗(yàn) 通過看 聽 觸 測(cè)等判斷找故障已不適于現(xiàn) 代工業(yè)向大型化 連續(xù)化和現(xiàn)代化方向發(fā)展 必須使液壓系統(tǒng)故障診斷現(xiàn)代化 加強(qiáng)專家系統(tǒng)的研究 要總結(jié)專家的知識(shí) 建立完整的 具有學(xué)習(xí)功能的專家知識(shí)庫(kù) 并利用計(jì)算機(jī)根據(jù)輸入的現(xiàn)象和知識(shí)庫(kù) 中知識(shí) 用推理機(jī)中存在的推理方法 推算出引出故障的原因 提高維修方案和預(yù)防措施 要進(jìn)一步 引發(fā)液壓系統(tǒng)故障診斷專家系統(tǒng)通用工具軟件 對(duì)于不同的液壓系統(tǒng)只需修改和增減少量的規(guī)則 另 外開發(fā)液壓系統(tǒng)自補(bǔ)償系統(tǒng)也是液壓行業(yè)努力的方向 3 機(jī)電一體化 電子技術(shù)和液壓傳動(dòng)技術(shù)相結(jié)合 使傳統(tǒng)的液壓傳協(xié)與控制技術(shù)增加了活力 擴(kuò)大了應(yīng)用領(lǐng)域 實(shí)現(xiàn)機(jī)電一體化可以提高工作可靠性 實(shí)現(xiàn)液壓系統(tǒng)柔性化 智能化 改變液壓系統(tǒng)效率低 漏油 維修性差等缺點(diǎn) 充分發(fā)揮液壓傳動(dòng)出力大 貫性小 響應(yīng)快等優(yōu)點(diǎn) 其主要發(fā)展動(dòng)向如下 1 電液伺服比例技術(shù)的應(yīng)用將不斷擴(kuò)大 液壓系統(tǒng)將由過去的電氣液壓 on oE 系統(tǒng)和開環(huán)比例控 制系統(tǒng)轉(zhuǎn)向閉環(huán)比例伺服系統(tǒng) 為適應(yīng)上述發(fā)展 壓力 流量 位置 溫度 速度 加速度等傳感器應(yīng) 實(shí)現(xiàn)標(biāo)準(zhǔn)化 計(jì)算機(jī)接口也應(yīng)實(shí)現(xiàn)統(tǒng)一和兼容 2 發(fā)展和計(jì)算機(jī)直接接口的功耗為 5mA 以下電磁閥 以及用于脈寬調(diào)制系統(tǒng)的高頻電磁閥 小于 3mS 等 3 液壓系統(tǒng)的流量 壓力 溫度 油的污染等數(shù)值將實(shí)現(xiàn)自動(dòng)測(cè)量和診斷 由于計(jì)算機(jī)的價(jià)格降 低 監(jiān)控系統(tǒng) 包括集中監(jiān)控和自動(dòng)調(diào)節(jié)系統(tǒng)將得到發(fā)展 4 計(jì)算機(jī)仿真標(biāo)準(zhǔn)化 特別對(duì)高精度 高級(jí) 系統(tǒng)更有此要求 5 由電子直接控制元件將得到廣泛采用 如電子直接控制液壓泵 采用通用化控制機(jī)構(gòu)也是今后 需要探討的問題 液壓產(chǎn)品機(jī)電一體化現(xiàn)狀及發(fā)展 二 實(shí)驗(yàn)臺(tái)的組成 實(shí)驗(yàn)臺(tái)由三大部分組成 即液壓泵站 實(shí)驗(yàn)操作臺(tái)和電氣控制系統(tǒng) 在總體布置上 充分考慮到 使用方便及空間布置緊湊 液壓泵站即液壓源 用來將液壓油提供給實(shí)驗(yàn)臺(tái) 系統(tǒng)采用一臺(tái)變量柱塞 泵供油 泵站安裝有蓄能器 用于吸收系統(tǒng)油液脈動(dòng) 提供均勻穩(wěn)定的壓力油 根據(jù)實(shí)際需要 設(shè)計(jì) 系統(tǒng)最高工作壓力為 6 3MPa 為了使泵站維修方便和主操作平臺(tái)大小適中 操作方便 將液壓泵 電 機(jī) 蓄能器等外置 實(shí)驗(yàn)操作平臺(tái)上安裝各種測(cè)試儀表及傳感器 可根據(jù)需要將元件或元件與油路塊 之間通過液壓硬管或軟管進(jìn)行連接 電氣控制系統(tǒng)主要包括實(shí)驗(yàn)用的電控設(shè)備及操縱裝置 如油溫自 控及操縱裝置 電擊啟動(dòng)器 電表以及各種操作按鈕 液壓源驅(qū)動(dòng)電動(dòng)機(jī)起動(dòng)和停止 事故急停 等 考慮到結(jié)構(gòu)緊湊 將電氣控制部分放置在操作臺(tái)下部 重要操作按鈕放在操作臺(tái)上部 三 實(shí)驗(yàn)的重要性 在人類對(duì)自然界規(guī)律的探索和認(rèn)識(shí)過程中 科學(xué)實(shí)驗(yàn)是必不可少的一個(gè)重要環(huán)節(jié) 可以說沒有實(shí) 驗(yàn)也就沒有現(xiàn)代科學(xué) 當(dāng)然 在科學(xué)實(shí)驗(yàn)中人是應(yīng)一直居于主導(dǎo)地位的 人們?cè)讷@得感性認(rèn)識(shí)的基礎(chǔ) 上 必須通過頭腦的綜合和思維 上升成為理性認(rèn)識(shí) 提出假設(shè)和廣義的規(guī)律性結(jié)論 為了檢驗(yàn)和驗(yàn) 證理性結(jié)論的正確性 人們還必須主動(dòng)地 積極的投身到科學(xué)實(shí)驗(yàn)中去 用理論來指導(dǎo)實(shí)驗(yàn)的進(jìn)行 并由實(shí)驗(yàn)結(jié)果的分析中來不斷充實(shí) 驗(yàn)證和發(fā)展理論 增加理論的深度和廣度 因此 對(duì)于每一個(gè)獻(xiàn) 身于科學(xué)的人 特別是工程技術(shù)人員 都應(yīng)對(duì)所從事的學(xué)科中的實(shí)驗(yàn)技術(shù)予以充分的重視 實(shí)驗(yàn)技術(shù)涉及的知識(shí)面比較廣 如 機(jī)械學(xué) 電工學(xué) 計(jì)算技術(shù) 應(yīng)用光學(xué) 液壓流體力學(xué) 數(shù)理 統(tǒng)計(jì)及現(xiàn)代控制理論等 且實(shí)驗(yàn)技術(shù)本身隨著科學(xué)技術(shù)的發(fā)展 也在日新月異地更新和發(fā)展 隨著科學(xué)技術(shù)的發(fā)展 液壓技術(shù)的發(fā)展也非常迅速 其應(yīng)用范圍也愈來愈廣 因而對(duì)它的元件和 系統(tǒng)的性能要求也就愈來愈高 因此 為了確定和考核液壓系統(tǒng)及其組成元件完整的性能參數(shù) 品質(zhì) 指標(biāo)等所進(jìn)行的測(cè)試 實(shí)驗(yàn)工作 也就需要滿足更高的要求 液壓教學(xué)要與液壓技術(shù)發(fā)展同步 需要 引進(jìn)先進(jìn)技術(shù)設(shè)備 讓學(xué)生了解不斷發(fā)展的液壓技術(shù)狀況 并通過教學(xué)實(shí)驗(yàn)掌握它們 以培養(yǎng)真正能 夠適應(yīng)社會(huì)發(fā)展的液壓技術(shù)人才 四 實(shí)驗(yàn)臺(tái)的工作原理 實(shí)驗(yàn)臺(tái)原理圖如圖 1 所示 電磁溢流閥 10 用于調(diào)定系統(tǒng)壓力 電液換向閥 11 用于控制主油路中 油流方向 單向節(jié)流閥 15 用于調(diào)節(jié)系統(tǒng)流量 減壓閥 12 與電磁換向閥 16 用于調(diào)節(jié)控制油的壓力和方向 測(cè)試壓力表 19 可與各測(cè)壓接頭 17 快速換接 以靈活方便地測(cè)壓 負(fù)載由單向閥橋式回路中的溢流閥 20 或節(jié)流閥 21 調(diào)節(jié) 外接液壓設(shè)備 18 用于被試缸或馬達(dá)的加載等 圖 1 液壓綜合實(shí)驗(yàn)臺(tái)原理 1 油箱 2 液位液溫計(jì) 3 過濾器 4 電接點(diǎn)溫度表 5 空濾器 6 泵 電機(jī)組 7 液壓軟管 8 冷卻器 9 單向閥 10 電磁溢流閥 11 16 電液換向閥 12 減壓閥 13 高壓球閥 14 渦輪流量計(jì) 15 單向節(jié) 流閥 17 測(cè)壓接頭 18 外接液壓設(shè)備 19 測(cè)試壓力表 20 溢流閥 21 節(jié)流閥 22 蓄能器 板式閥測(cè) 試底板 測(cè)試接管 五 小結(jié) 綜合液壓實(shí)驗(yàn)臺(tái)的設(shè)計(jì)是一項(xiàng)復(fù)雜的工作 涉及的知識(shí)面很廣 技術(shù)要求很高 隨著機(jī)電液一體 化技術(shù)的不斷發(fā)展 人們對(duì)于利用機(jī)電液一體化技術(shù)來研發(fā)綜合液壓實(shí)驗(yàn)臺(tái)的觀念將更趨于成熟 它 有著設(shè)計(jì)周期短 操作方便 工作效率高等優(yōu)點(diǎn) 整個(gè)設(shè)計(jì)工作使我得到了鍛煉 不僅僅擴(kuò)寬了我的 知識(shí)面 而且還培養(yǎng)了我的創(chuàng)新能力和實(shí)踐能力 總之 在這次設(shè)計(jì)工作中使我受益匪淺 也有了 成就感 不僅僅擴(kuò)寬了我的知識(shí)面 而且還培養(yǎng)了我的創(chuàng)新能力和實(shí)踐能力 把書本中學(xué)到的知識(shí)確 實(shí)用到了實(shí)踐中 為以后的工作打下了基礎(chǔ) The Sunflower Seed Huller and Oil Press IN 2 500 SQUARE FEET a family of four can grow each year enough sunflower seed to produce three gallons of homemade vegetable oil suitable for salads or cooking and 20 pounds of nutritious dehulled seed with enough broken seeds left over to feed a winter s worth of birds The problem heretofore with sunflower seeds was the difficulty of dehulling them at home and the lack of a device for expressing oil from the seeds About six months ago we decided to change all that The job was to find out who makes a sunflower seed dehuller or to devise one if none were manufactured And to either locate a home scale oilseed press or devise one No mean task Our researches took us from North Dakota hub of commercial sunflower activity in the nation to a search of the files in the U S Patent Office with stops in between We turned up a lot of big machinery discovered how difficult it is to buy really pure unrefined vegetable oils but found no small scale equipment to dehull sunflowers or press out their oil The key to success however was on our desk the whole time In spring 1977 August Kormier had submitted a free lance article describing how he used a Corona grain mill to dehull his sunflower seeds and his vacuum cleaner exhaust hose to blow the hulls off the kernels A second separation floated off the remaining hulls leaving a clean product We d tried it but because some kernels were cracked and the process involved drying we hadn t been satisfied Now we felt the best approach was to begin again with what we learned from Mr Kormier and refine it Staff Editor Diana Branch and Home Workplace Editor Jim Eldon worked with a number of hand and electric powered grain mills While the Corona did a passable job they got the best results with the C S Bell 60 hand mill and the Marathon Uni Mill which is motor driven I couldn t believe my eyes the first time I tried the Marathon Diana says I opened the stones to 1 8th inch and out came a bin full of whole kernels and hulls split right at the seams What a thrill that was She found that by starting at the widest setting and gradually narrowing the opening almost every seed was dehulled The stones crack the hulls open then rub them to encourage the seed away from the fibrous lining The Bell hand mill worked almost as well As long as the stones open at least as wide as the widest unhulled seed any mill will work she says Because the seed slips through the mill on its flat side grading is an important step to take before dehulling We made three sizing boxes The first is 1 4 inch hardware cloth wire screen The second is two layers of 1 4 inch cloth moved slightly apart to narrow the opening in one direction and the third is two layers of screen adjusted to make a still smaller opening Since the smallest unhulled seeds are about the size of the largest hulled kernels the grading step prevents these undersized seeds from passing through unhulled Processed together at a closer setting the smallest seeds hulled out Jim Eldon s workshop is littered with strange looking pieces of apparatus They represent initial attempts to build a workable winnowing box using Kormier s vacuum exhaust idea for a source of air Jim Fred Matlack and Diana finally made a box with a Plexiglas front through which they could observe what was happening They cut a hole in the back of the box with a sliding cover to regulate the air pressure and fiddled with various arrangements of baffles The result was a stream of hulls exiting through one hole while the kernels fell to the bottom of the box Now they were ready to try a five pound sample of unhulled sunflower seeds to see how much they could recover The five pounds were graded and dehulled then winnowed We got about one hull for every ten kernels in the final winnowed product These are easily picked out They usually contain kernels still held behind the fibrous strings of the hull Their weight prevents them from blowing out with the empty hulls We found that bug eaten seeds do blow away with the chaff which was a bonus for cleanliness of the final product Toss the hulls to the birds who will find broken seeds among them Starting with 80 ounces of unhulled seed we ended up with 41 1 4 ounces of edible whole seeds 1 8 ounces of damaged seeds suitable for animal feed and 36 6 ounces of hulls It took us about an hour Not bad Sunflower seeds store perfectly in the hulls but they deteriorate more rapidly when shelled out The grain mill dehuller and winnowing box give the gardener a way to have the freshest possible seeds for eating at all times of the year With the construction of one more piece of equipment the oil press he can have absolutely fresh unrefined polyunsaturated sunflower oil for salads mayonnaise and cooking Most light refined vegetable oils have been extracted using hexane a form of naphtha The oil is then heated to boil off the hexane Lye is dumped into it It s washed with steam then heated to remove odors and taste before being laced with preservatives and stabilizers It may feel oily in the mouth but you might as well taste air No so with fresh made sunflower oil it s deliciously yet subtly nutty in flavor adding unsurpassed flavor to salads There s good reason to believe that sunflower oil may become the 1 vegetable oil in the U S in a few years It s already 1 in health conscious Europe Corn oil has already caught on here for health reasons and sunflower oil is so much better Sunflower oil s 70 percent polyunsaturate is just under safflower with corn oil bringing up the rear with 55 percent And sunflowers yield 40 percent oil soybeans only 20 percent Our oil press is relatively simple but it must be welded together Check the construction directions for details The press consists of a welded tubular frame which accepts a three ton hydraulic jack You may already have one If not it can be purchased at most auto and hardware stores for about 16 A metal canister with holes drilled in its sides and one end welded shut holds the mashed sunflower seeds A piston is inserted in the canister and then inverted and slipped over a pedestal on the frame The jack is set in place and the pressure gradually increased over half an hour The oil drips from the sides of the canister into a tray the bottom of a plastic jug slipped over the pedestal works fine which empties the oil into a cup You can filter the oil with a coffee filter to remove pieces of seed and other fine particles that would burn if the oil were used for cooking If it s for salads or mayonnaise there s no need to filter it We first tried using confectionary sunflower seeds for oil These are the regular eating kernels we re used to seeing They give less than half as much oil as the oilseed types of sunflower Although you can use confectionary types such as MAMMOTH RUS SIAN for oil don t expect to get more than an ounce and a half from a pound of seed Oilseed produces three or more ounces of oil from a pound of seed and is well worth planting along with confectionary type seeds Oilseed has another big advantage to prepare it you can put the whole unhulled seed into a blender and whiz it until it forms a fine meal while confectionary seeds must be dehulled first The entire sequence of grading dehulling and winnowing is avoided with oilseed Oil types produce about a tenth of a pound of seed per head in commercial production Gardeners with their better soil and care invariably do better than that Our conservative estimate is that 1 280 plants will be enough for three gallons of oil Spaced one foot apart in rows two feet apart 1 280 oilseed plants will take a space 40 by 56 feet or 80 by 28 if you want a more rectangular patch to face south We worked in pound batches since the canister just holds one pound of mash After blending we heated it to 170 degrees F 77 deg C by placing it in a 300 degree F 149 deg C oven and stirring it every five minutes for 20 minutes Heating gets the oil flowing and doubles the yield of oil In case you re wondering cold pressed oils sold commercially are also heated and some are subjected to the entire chemical process The term has no firm meaning within the industry according to the literature we ve surveyed Heating does not change the structure of fats It will not turn polyunsaturated fats into saturated fats In fact Dr Donald R Germann in his book The Anti Cancer Diet says that an unsaturated fat must be heated to high temperatures above 425 degrees F or 200 degrees C at least 8 or 10 times before any shift toward saturation occurs Dean C Fletcher Ph D of the American Medical Association Department of Foods and Nutrition in Chicago says It s true that either high temperature or repeated heating does change the nature of some of the unsaturated oil molecules But the flavor of the oil changes as these chemical changes occur spoiling its taste This effect is probably more profound than any of the physiological changes the altered oil might produce within the body From 500 gm of heated mash we pressed 89 gm of oil 89 percent of the entire amount available and twice as much as we could press from unheated oil The decision is up to you whether or not to heat the mash but that extra 50 percent seems like an awful lot especially when the whole technique is so labor intensive The oil should be stored in the refrigerator and it s probably best to use it within a month since it has no preservatives Mayonnaise made with such fresh oils should be kept refrigerated and used within two weeks The leftover cake still containing 50 percent of its oil is a nutritious addition to your dishes and makes excellent feed for animals or winter birds Store the pressed cake in the freezer We re talking then about a sunflower patch with two kinds of plants confectionary such as MAMMOTH RUSSIAN and oilseed such as PEREDOVIK The oilseed plants should be grown 12 inches apart in rows two feet apart Four average confectionary heads yield about a pound of unhulled seed You ll need about 35 pounds of unhulled seed or 140 plants worth to yield 20 pounds of hulled kernels about what a family of four will use in a year That many plants can be grown in an area 26 by 10 feet That s 260 square feet Put that together with the 2 240 square feet for the oilseed sunflowers and you need a patch about 2 500 square feet 25 100 foot rows to keep yourself supplied year round with super nutrition and unsurpassable taste Winnowing Machine For Sunflower Seeds The winnowing machine operates on the age old principle of blowing the chaff away from the heavy grain with a controlled current of air The unit uses a household or shop type vacuum cleaner for its air supply A vacuum cleaner was used as a power source because it can supply a large volume of air over an extended period of time and most homes and farms have a vacuum cleaner A cloth bag has been attached to the chaff chute to catch the chaff as it is separated from the seed The bag allows the hulls to be collected and greatly reduces the amount of waste material normally blown into the air by conventional systems The unit has been constructed in such a way that the cloth bag and cleaner box can be placed inside the seed box making a compact package for storage Tools Required 1 Table Saw 2 Drill Press 3 Band Saw 4 Saber Saw Procedure cleaner box 1 Cut out the two sides of the cleaner box from 1 4 inch plywood 2 Cut out the six interior pieces of the cleaner box from 3 4 x 3 1 2 inch select pine 3 Assemble the cleaner box elements with glue and nails 4 Cut four 1 4 inch square strips of pine four inches long 5 Glue the strips around the end of the chaff chute 6 Sand all surfaces and edges 7 Finish with clear lacquer finish Procedure seed box 1 Cut two pieces of pine 34 x 5 12 x 15 inches for the sides 2 Cut two pieces of pine 3 4 x 5 1 2 x inches for the top and bottom 3 Plow a 14 x 1 4 groove for the front and back panels in all four pieces 4 Rip the top board to 5 inches so that the front panel can slide into the grooves in the side boards 5 Rabbet both ends of each 15 inch side piece to accept the top and bottom boards 6 Drill a hole in the left side board 2 1 2 inches from the top The size of the hole is determined by the vacuum cleaner hose fitting 7 Cut a 3 1 4 x 4 inch hole in the top 1 2 inch from the right end This hole will accept the cleaner box 8 Cut two pieces of pine for the baffle 9 Drill two 1 inch holes in the bottom of the baffle box 10 Cut a piece of 1 4 x 8 1 2 x 14 inch plywood for the back panel 11 Cut a 3 inch hole centered 1 7 8 inches from the top and left sides of the plywood back 12 Assemble the sides baffles top bottom and back panel with glue and nails 13 Cut an 8 7 16 x 15 3 4 inch piece of Plexiglas for the front 14 Cut a one inch radius on the top corners of the front and sand the edges 15 Drill a one inch thumb hole centered 7 8 inch from the top edge 16 Cut a 3 1 2 inch disk of 1 4 inch plywood for the vent cover 17 Drill a 3 16 inch hole 3 8 inch from the edge of the disk 18 Mount the disk over the vent with a 10 x 1 inch screw 19 Sand all surfaces and edges of the box 20 Finish with clear lacquer finish Materials Cleaner Box 2 7 3 4 x 7 1