專用銑床液壓系統(tǒng)設計
專用銑床液壓系統(tǒng)設計,專用銑床液壓系統(tǒng)設計,專用,銑床,液壓,系統(tǒng),設計
鎮(zhèn) 江 高 專
ZHENJIANG COLLEGE
畢 業(yè) 設 計 任 務 書
題 目∶ 專用銑床液壓系統(tǒng)設計
系 名: 機械系
專業(yè)班級: 機電W071
學生姓名: 束汝堅
學 號: 070108120
指導教師姓名: 戴月紅
指導教師職稱: 講師
二○一二年 二 月 十五 日
課題名稱
專用銑床液壓系統(tǒng)設計
同組學生姓名
無
設計(研究)內(nèi)容:
一臺專用銑床,銑頭驅(qū)動電機功率為7.5KW,銑刀直徑為120mm,轉(zhuǎn)速為350r/min,工作臺重量為4000N,工件和夾具最大重量為1500N,工作臺行程為400mm,(快進300mm,工進100mm)??爝M速度為4.5m/min,快進速度與快退速度相等近似,工進速度為60—1000mm/min。其往復運動始末的加減速時間為0.05s。工作臺用平導軌,靜摩擦系數(shù)為0.2,動摩擦系數(shù)為0.1。
符合以下要求,方可參加答辯:
(1)液壓系統(tǒng)原理圖及速度循環(huán)圖、負載循環(huán)圖、電磁閥動作循序表 一張A1
(2) 液壓缸裝配圖 一張A1
(3)液壓缸主要零件的零件圖 五張A3
(4) 設計計算說明書,字數(shù)不少于5000字 一份
(5)以上資料打印稿和電子版(圖紙用AutoCAD2004版本存盤、說明書及任務書用Word2003存盤)各一份
參考文獻:
1. 《液壓傳動》 丁樹模主編 機械工業(yè)出版社
2. 《液壓與氣壓傳動》 左健民主編 機械工業(yè)出版社
3. 《液壓與氣動技術(shù)》 張宏友主編 大連理工大學出版社
4. 《液壓系統(tǒng)設計簡明手冊》 楊培元、朱福元主編 機械工業(yè)出版社
5. 《液壓傳動設計指南》 張利平主編 化學工業(yè)出版社
6. 《液壓與氣壓傳動》 游有鵬主編 科學出版社
進 度 計 劃 表
序號
起止 日期
計劃完成內(nèi)容
實際完成情況
檢 查 日 期
檢查人簽名
1
2.15-2.28
了解設計內(nèi)容, 了解必要的設計步驟和方法,確定總體方案。
1、提前完成 ( )
2、按時完成 ( )
3、基本完成 ( )
4、未完成 ( )
2
3.1-3.15
完成設計核心內(nèi)容的計算,初定系統(tǒng)原理圖和油缸的形式。
1、提前完成 ( )
2、按時完成 ( )
3、基本完成 ( )
4、未完成 ( )
3
3.16-3.31
完成畢業(yè)設計論文初稿。 (包括設計說明書的輸入及編輯等)
1、提前完成 ( )
2、按時完成 ( )
3、基本完成 ( )
4、未完成 ( )
4
4.1-4.15
設計液壓缸的結(jié)構(gòu),在計算機上繪制所有圖紙。(包括系統(tǒng)原理圖,液壓缸裝配圖及主要零件圖)
1、提前完成 ( )
2、按時完成 ( )
3、基本完成 ( )
4、未完成 ( )
5
4.16-4.30
設計說明書及圖紙第一次修改補充。
1、提前完成 ( )
2、按時完成 ( )
3、基本完成 ( )
4、未完成 ( )
6
5.1-5.31
設計說明書及圖紙第二次修改補充。
1、提前完成 ( )
2、按時完成 ( )
3、基本完成 ( )
4、未完成 ( )
7
6.1-6.19
完善并打印提交全部資料。(含電子版)
1、提前完成 ( )
2、按時完成 ( )
3、基本完成 ( )
4、未完成 ( )
8
6.20-6.23
作好答辯前的準備工作。
1、提前完成 ( )
2、按時完成 ( )
3、基本完成 ( )
4、未完成 ( )
畢業(yè)設計(論文)評語及評分(指導教師專用)
學生姓名
束汝堅
專業(yè)班級
機電W071
總 分
評 分 內(nèi) 容
評 分 等 級
好
較好
一般
差
應用文獻資料和調(diào)研能力
分析與解決問題的能力(包括計算方法、數(shù)據(jù)處理等)
計算機能力(包括編程、數(shù)據(jù)、圖形及文字處理)
論文質(zhì)量(論點、論據(jù)、實驗分析、推理、深度等)
設計質(zhì)量(方案、技術(shù)路線、設計水平、圖面質(zhì)量等)
工作量、工作態(tài)度
技術(shù)經(jīng)濟分析能力(包括技術(shù)可靠性、經(jīng)濟合理性的分析評價)
創(chuàng)新 (包括創(chuàng)新意識、獨特見解)
寫作的規(guī)范性
指導教師評語:
該同學在畢業(yè)設計期間,設計態(tài)度(端正、較好、尚可、較差),(能、基本能、不能)遵守畢業(yè)設計紀律和相關(guān)規(guī)定,(設計工作量(多、飽滿、較輕、不足),(完成、基本完成、沒用完成)相關(guān)的畢業(yè)實習和調(diào)研任務,(能較好地、尚能、不能)處理好畢業(yè)設計與工作實習的關(guān)系。
該同學(獨立、基本獨立、根據(jù)參考、不能獨立)完成畢業(yè)設計規(guī)定的任務。設計方案(正確、基本正確、尚正確、不夠正確),結(jié)構(gòu)(合理、較合理、尚合理、不夠合理);圖面質(zhì)量(好、較好、一般、較差);說明書的寫作(規(guī)范、較規(guī)范、尚規(guī)范、不夠規(guī)范),計算能力(好、較好、一般、尚可、較差)。
本設計已達到的標準為(優(yōu)秀、良好、中等、及格、不及格)。
指導教師簽字:
年 月 日
注:各評語在相應的檔次上畫上“√”。
畢業(yè)設計(論文)評語及評分(主審教師專用)
學生姓名
束汝堅
專業(yè)班級
機電W071
總 分
評 分 內(nèi) 容
評 分 等 級
好
較好
一般
差
總體設計方案
零部件設計方案
圖
紙
質(zhì)
量
和
有
關(guān)
技
術(shù)
標
準
視 圖
圖紙幅面
標注
技術(shù)條件
標題欄
明細欄
圖號
說
明
書
質(zhì)
量
格式的規(guī)范性
內(nèi)容的完整性
分析的正確性
深 度
創(chuàng) 新
其它(資料袋、裝訂要求等)
備注:
主審教師簽字:
注:各評語在相應的檔次上畫上“√”。
年 月 日
畢業(yè)設計(論文)評語及評分(答辯小組專用)
學生姓名
束汝堅
專業(yè)班級
機電W071
總 分
評 分 內(nèi) 容
評 分 等 級
好
較好
一般
差
學生陳述清楚、精練、正確、邏輯性強
論文質(zhì)量(論點、論據(jù)、實驗分析、推理、深度、創(chuàng)新等)
設計質(zhì)量(方案、技術(shù)路線、設計水平、圖面質(zhì)量、創(chuàng)新等)
問題:
1、
2、
3、
答辯小組意見:
該同學設計方案(正確、基本正確、尚正確、不夠正確),結(jié)構(gòu)(合理、較合理、尚合理、不夠合理);圖面質(zhì)量(好、較好、一般、較差);說明書寫作(規(guī)范、較規(guī)范、尚規(guī)范、不夠規(guī)范)。在答辯中的陳述(清楚、較清楚、尚清楚、不夠清楚) ,對所提問題的回答(正確、基本正確、尚正確、不夠正確), 對基礎知識和專業(yè)知識的基本掌握(好、較好、一般、尚好、較差),(已達到、未達到)畢業(yè)設計的要求。
答辯小組成員:
答辯小組組長 年 月 日
最 終 評 定 成 績
注:各評語在相應的檔次上畫上“√”。
5
鎮(zhèn) 江 高 專
ZHENJIANG COLLEGE
畢 業(yè) 設 計 (論 文)
專用銑床液壓系統(tǒng)設計
Special milling machine hydraulic system design
系 名: 機械系
專業(yè)班級: 機電W071
學生姓名: 束汝堅
學 號: 070108120
指導教師姓名: 戴月紅
指導教師職稱: 講師
二○一二 年 六 月
目 錄
引 言 5
第一章 概述 6
1.1 設計的目的 6
1.2 設計的要求 6
1.3 設計題目 7
第二章 工況分析 8
2.1 工作負載 8
2.2 摩擦阻力 8
2.3 慣性負載 8
第三章 繪制負載圖、速度圖和動作循環(huán)圖 9
第四章 初步確定液壓缸的參數(shù) 11
4.1初步確定液壓缸的參數(shù) 11
4.2 計算液壓缸的尺寸 11
4.3 液壓缸工況 11
第五章 擬定液壓原理圖 14
5.1選擇液壓基本回路 14
5.2 組成系統(tǒng)圖 16
第六章 選擇液壓元件 18
6.1液壓傳動系統(tǒng) 18
6.2 液壓裝置的結(jié)構(gòu)設計,繪制工作圖及編譯技術(shù)文件 18
6.3 液壓傳動系統(tǒng)參數(shù)及元件選擇 18
6.4 確定系統(tǒng)工作壓力 19
6.5執(zhí)行元件控制方案擬定 19
6.6確定執(zhí)行元件的主要參數(shù) 19
6.7確定液壓泵的工作壓力和流量計算 20
6.8控制閥的選擇 20
6.9確定油箱直徑 20
第七章 液壓系統(tǒng)的性能驗算 21
結(jié) 論 23
致 謝 24
參考文獻: 25
專用銑床液壓系統(tǒng)設計
專業(yè)班級:機電WO71 學生姓名:束汝堅
指導教師:戴月紅 職稱:講師
摘要 液壓系統(tǒng)是以電機提供動力基礎,使用液壓泵將機械能轉(zhuǎn)化為壓力,推動液壓油。通過控制各種閥門改變液壓油的流向,從而推動液壓缸做出不同行程、不同方向的動作。完成各種設備不同的動作需要。液壓系統(tǒng)已經(jīng)在各個工業(yè)部門及農(nóng)林牧漁等許多部門得到愈來愈廣泛的應用,而且愈先進的設備,其應用液壓系統(tǒng)的部分就愈多。所以像我們這樣的大學生學習和親手設計一個簡單的液壓系統(tǒng)是非常有意義的。
關(guān)鍵詞 液壓傳動、穩(wěn)定性、液壓系統(tǒng)
Special milling machine hydraulic system design
Abstract The special milling machines, hydraulic system design in the design programme and the hydraulic system shall be able to finish the work into fast forward, and backed out when the milling machine architecture to understand and grasp for the hydraulic knowledge on the basis of from a given conditions, and the value analysis of the theory with practice, the work of drawing in autocad software diagram of the hydraulic system, the principle of the assembly drawing and analyzing the parts, the process, Set down to a time too short, the time of the short, at the start of the larger, slow down a short time will result in oscillatory too much, so damage to equipment, make failure of the jug, the main argument is based on innovation innovation power, the motor drivers head first, revolution speed and work in the process of the maximum load and the itinerary for design calculations. Friction factor is also a need to think of it. although friction of the relatively small, but will also be affected. the design of the difficulty is mainly the principle of the analysis and design purpose is to achieve appropriate control, and to choose a relative rationality, high precision, economically affordable hydraulic components, and design talents widely used.
Key words hydraulic transmission, control system, hydraulic system.
引 言
目前,隨著電子、信息等高新技術(shù)的不斷發(fā)展及市場需求個性化與多樣化,世界各國都把機械制造技術(shù)的研究和開發(fā)作為國家的關(guān)鍵技術(shù)進行優(yōu)先發(fā)展,將其他學科的高技術(shù)成果引入機械制造業(yè)中。 因此機械制造業(yè)的內(nèi)涵與水平已今非昔比,它是基于先進制造技術(shù)的現(xiàn)代制造產(chǎn)業(yè)??v觀現(xiàn)代機械制造技術(shù)的新發(fā)展,其重要特征主要體現(xiàn)在它的綠色制造、計算機集成制造、柔性制造、虛擬制造、智能制造、并行工程、敏捷制造和網(wǎng)絡制造等方面。
近年來,我國的工程機械取得了蓬勃的發(fā)展,其中,液壓傳動技術(shù)起到了至關(guān)重要的作用。而且,隨著液壓傳動技術(shù)的快速發(fā)展和廣泛應用,它已成為農(nóng)業(yè)機械、工程建筑機械等行業(yè)不可缺少的重要技術(shù)。
然而,盡管液壓技術(shù)在機械能與壓力能的轉(zhuǎn)換方而,已取得很大進展,但它在能量損失和傳動效率上仍然存在著問題。因為,在液壓系統(tǒng)中,隨著油液的流動,有相當多的液體能量損失掉,這種能量損失不僅體現(xiàn)在油液流動過程中的內(nèi)摩擦損失上,還反映在系統(tǒng)的容積損失上,使系統(tǒng)能量利用率降低,傳動效率無法提高。高能耗和低效率又使油液發(fā)熱增加,使性能達小到理想的狀況,給液壓技術(shù)的進一步發(fā)展帶來障。因此,探索和研究高效液壓傳動技術(shù),提高其綜合性能就成為了液壓技術(shù)領域研究的重點之一
第一章 概述
1.1 設計的目的
液壓傳動系統(tǒng)設計是本設計的一個綜合實踐性教學環(huán)節(jié),通過該教學環(huán)節(jié),要求達到以下目的;
1.鞏固和深化已學知識,掌握液壓系統(tǒng)設計計算的一般方法和步驟,培養(yǎng)學生工程設計能力和綜合分析問題、解決問題能力;
2.正確合理地確定執(zhí)行機構(gòu),選用標準液壓元件;能熟練地運用液壓基本回路、組合成滿足基本性能要求的液壓系統(tǒng);
3.熟悉并會運用有關(guān)的國家標準、部頒標準、設計手冊和產(chǎn)品樣本等技術(shù)資料。對學生在計算、制圖、運用設計資料以及經(jīng)驗估算、考慮技術(shù)決策、CAD技術(shù)等方面的基本技能進行一次訓練,以提高這些技能的水平。
1.2 設計的要求
1.設計時必須從實際出發(fā),綜合考慮實用性、經(jīng)濟性、先進性及操作維修方便。如果可以用簡單的回路實現(xiàn)系統(tǒng)的要求,就不必過分強調(diào)先進性。并非是越先進越好。同樣,在安全性、方便性要求較高的地方,應不惜多用一些元件或采用性能較好的元件,不能單獨考慮簡單、經(jīng)濟;
2.獨立完成設計。設計時可以收集、參考同類機械的資料,但必須深入理解,消化后再借鑒。不能簡單地抄襲;
3.在設計的過程中,要隨時復習液壓元件的工作原理、基本回路及典型系統(tǒng)的組成,積極思考。不能直接向老師索取答案;
4.液壓傳動設計的題目均為中等復雜程度液壓設備的液壓傳動裝置設計。具體題目由指導老師分配,題目附后;
5.液壓傳動設計一般要求學生完成以下工作:
(1)液壓系統(tǒng)原理圖及速度循環(huán)圖,負載圖,電磁發(fā)動工作循環(huán)表 一張A1
(2)液壓缸裝配圖 一張A1
(3)液壓缸主要零件的零件圖 五張(A3)
(4)設計計算說明書,字數(shù)不少于5000字
(5)以上資料打印稿和電子版(圖紙用AutoCAD2004版本存盤,說明書及任務書用Word2003存盤)各一份。
1.3 設計題目
一臺專用銑床的銑頭驅(qū)動電機的功率N= 7.5KW ,銑刀直徑D=120mm,轉(zhuǎn)速n=350rpm,工作臺重量G1=4000N,工件及夾具重量G2=1500N,工作臺行程L=400mm,(快進300mm,工進100mm)快進速度為4.5m/min,工金速度為60~1000mm/min,其往復運動和加速(減速)時間t=0.05s,工作臺用平導軌,靜摩擦系數(shù)fs=0.2,動摩擦系數(shù)fd=0.1。設計其液壓控制系統(tǒng)。
第二章 工況分析
2.1 工作負載
2.2 摩擦阻力
2.3 慣性負載
查液壓缸的機械效率,可計算出液壓缸在各工作階段的負載情況,如下表所示:
液壓缸各階段的負載情況表
工 況
負載計算公式
液壓缸負載
液壓缸推力/N
啟 動
1100
1222.22
加 速
1390.98
1545.53
快 進
550
611.11
工 進
3960.46
4400.51
快 退
550
611.11
第三章 繪制負載圖、速度圖和動作循環(huán)圖
根據(jù)工況負載和以知速度和及行程S,可繪制負載圖和速度圖,如下圖所示:
負載循環(huán)圖
速度循環(huán)圖
動作循環(huán)圖
第四章 初步確定液壓缸的參數(shù)
4.1初步確定液壓缸的參數(shù)
查各類液壓設備常用工作壓力初選,
4.2 計算液壓缸的尺寸
選用差動液壓缸,無桿腔與有桿腔的有效面積為;回油路上有背壓閥或調(diào)壓閥,取背壓;回油管路壓力損失。
按JB2183—77取標準值 D=70mm
活塞桿的直徑為:
取標準值 d=50mm
由此求得液壓缸的實際有效工作面積
4.3 液壓缸工況
液壓缸各工作循環(huán)的負載、壓力、流量和功率數(shù)值表
工況
負載
回油腔壓力
進油腔壓力
輸入流量
輸入功率
計算公式
快進
啟動
1222.22
—
12.7
—
加速
1545.53
21.27
—
恒速
611.11
11.56
4.33
0.08
工進
4400.51
8
26.5
1.96~0.12
0.086
快退
啟動
1222.22
—
12.2
—
加速
1545.53
25.24
—
恒速
611.11
15.91
4.5
0.119
繪制液壓缸的工況圖
工況圖
第五章 擬定液壓原理圖
5.1選擇液壓基本回路
從工況圖可知:該系統(tǒng)的流量、壓力較小,可選用定量泵和溢流閥組成的供油源,如圖a所示。銑床加工有順銼和逆銼之分,宜采用出口節(jié)流調(diào)速,具有承受負切削的能力,如圖b所示??紤]到工作進給時負載大、速度低,而快進、快退行程中負載小、速度快,所以采用由換向閥聯(lián)通的差動快速回路,如圖c所示。根據(jù)一般專用銑床的要求不高,采用電磁閥的快慢換接回路,其特點是結(jié)構(gòu)簡單。選用簡便的電氣行程開關(guān)和擋鐵控制行程方式,如圖d所示。
(a) (b)
(c) (d)
按下SB1→工作臺快進→壓下2→工作臺工進→壓下SP1→工作臺快退→壓下1S→工作臺停止。
電液聯(lián)合控制如下:
(1)工作臺快進
按下按鈕SB1,中間繼電器K1得電動作并自鎖,其常開觸點閉合,使電磁鐵YV1得電。YV1得電使三位五通電液換向閥左位動作,工作臺向前快進移動。
(2)電磁鐵YV1得電。YV1得電使三位五通電液換向閥左位動作,
工作臺向前快速移動。
(3)工作臺工進
當工作臺快進到2檔被擋塊壓下時,其常開觸點閉合,使中間繼電器K2得電并自鎖,K2的常閉觸點斷開,二位二通機械換向閥關(guān)閉油液經(jīng)過調(diào)速閥實現(xiàn)工進。
(4)工作臺快退
當工作臺工進到壓力繼電器壓下SP1閉合,其常開觸點閉合,使K3得電動作并自鎖。K3的常閉觸點斷開,工作臺停止工進;其常開觸點閉合,使YV2得電。二位五通電液換向閥右位工作,工作臺快速退回。
(5)循環(huán)動作
當工作臺退到行程開關(guān)1S接通時,其常開觸點閉合,使K3斷開,YV1得電,工作臺停止。
電磁鐵動作順序表圖如下
電磁鐵動作順序表
5.2 組成系統(tǒng)圖
為了實現(xiàn)工作臺快退選用具單向閥的調(diào)速閥,圖為所設計的液壓系統(tǒng)圖。
27
液壓系統(tǒng)原理圖
第六章 選擇液壓元件
6.1液壓傳動系統(tǒng)
液壓元件的選擇,主要是計算它們的主要參數(shù)(如壓力和流量)來確定。一般先計算工作負載,再根據(jù)工作負載和工作要求的速度計算液壓缸的注意啊尺寸、工作壓力和流量或液壓馬達的排量,然后計算液壓泵的壓力,流量和液壓系統(tǒng)性能的驗算。
確定了各個液壓元件之后,要對液壓系統(tǒng)進行驗算。驗算內(nèi)容一般包括系統(tǒng)的壓力損失、發(fā)熱溫度、運動平穩(wěn)性和泄露量等。
6.2 液壓裝置的結(jié)構(gòu)設計,繪制工作圖及編譯技術(shù)文件
根據(jù)擬定的液壓系統(tǒng)原理圖繪制正式工作圖。正式工作圖包括
a. 液壓泵的型號、壓力、流量、轉(zhuǎn)速以及變量泵的調(diào)節(jié)范圍。
執(zhí)行元件的運轉(zhuǎn)速度,輸出的最大轉(zhuǎn)矩或推力、工作壓力以及工作行程等。
b. 所有執(zhí)行元件及輔助設備的型號及性能參數(shù)。
c. 管路元件的規(guī)格與型號。
d. 在繪制時,各元件的方向和位置,盡量與實際裝配時一致。
e. 設計該機床的液壓傳動系統(tǒng)
6.3 液壓傳動系統(tǒng)參數(shù)及元件選擇
對液壓系統(tǒng)進行分析,就是要查明它的每個執(zhí)行元件在各自工作過程中的運動速度和負載的變化規(guī)律。這是滿足設備規(guī)定的動作要求和承載能力所必須具備的。液壓系統(tǒng)承受的負載可由設備的規(guī)格規(guī)定,由樣機通過實驗測定。也可以有理論分析確定。當用理論分析確定系統(tǒng)的實際負載時,必須仔細考慮它所有的組成項目,例如工作負載(切削力、擠壓力、彈性塑性變形抗力、重力等)、慣性負載和阻力負載(摩擦力、背壓力)等,并把它們繪制成圖,同樣地,液壓執(zhí)行元件在各動作階段內(nèi)的運動速度也須相應地繪制成圖,設計簡單的液壓系統(tǒng)時,這兩種圖可以省略不畫。
6.4 確定系統(tǒng)工作壓力
系統(tǒng)工作壓力由設備類型、載荷大小、結(jié)構(gòu)要求和技術(shù)水平而定。系統(tǒng)工作壓力高,則省材料,機構(gòu)緊湊,重量輕,是液壓系統(tǒng)的發(fā)展方向;但要注意泄露、噪音控制和可靠性問題的妥善處理。系統(tǒng)工作壓力可根據(jù)負載來選取,也可根據(jù)設備類型選取。
6.5執(zhí)行元件控制方案擬定
根據(jù)已訂的液壓執(zhí)行元件、速度圖或動作線路圖,選擇適當?shù)膲毫刂?、方向控制、速度換接、差動連接回路,以實現(xiàn)對執(zhí)行元件的方向、出力及速度的控制。需要無級調(diào)速或無級變速時,可選擇的方案。有級變速比無級調(diào)速使用方便,適用于速度控制精度低,但要求速度能夠預置,以及在動作循環(huán)過程中有多重速度自動變換的場合。具體參見基本回路一章內(nèi)容。完成上述的選擇,所需液壓泵的類型就基本確定了。
6.6確定執(zhí)行元件的主要參數(shù)
根據(jù)液壓系統(tǒng)載荷圖和已確定的系統(tǒng)工作壓力,計算出液壓缸內(nèi)徑、活塞桿直徑,柱塞缸的柱塞直徑、柱塞桿直徑;根據(jù)液壓缸缸徑內(nèi)徑、活塞桿直徑、活塞桿直徑及行程的國家標準系列,確定主要參數(shù)。如采用液壓馬達,還需計算出液壓馬達的排量。
6.7確定液壓泵的工作壓力和流量計算
進油路的壓力損失取,回路泄露系數(shù)取,則液壓泵的最高工作壓力和流量為:
根據(jù)上述計算數(shù)據(jù)查泵的產(chǎn)品目錄,選用YB-6型定量葉片泵。
6.8控制閥的選擇
根據(jù)泵的工作壓力和通過各閥的實際流量,選取各元件的規(guī)格,如表所示。
各元件的規(guī)格表
序號
元件名稱
最大通流量/(L/min)
型號規(guī)格
1
定量葉片泵
6
YB-6
2
溢流閥
6
Y—10B
3
三位四通電磁閥
6
34D—10B
4
單向調(diào)速閥
6
QI—10B
5
二位三通電磁閥
6
23D—10B
6
單向閥
6
I—10B
7
過濾器
6
XU—B
6.9確定油箱直徑
進出液壓缸無桿腔的流量,在快退和差動工況時為所以管道流量按計算。取壓油管流速
,取內(nèi)徑為的管道。
吸油管的流速,通過流量為,則
,取內(nèi)徑為管道。
確定管道尺寸應與選定的液壓元件接口處的尺寸一致。
第七章 液壓系統(tǒng)的性能驗算
7.1 液壓系統(tǒng)的效率
(經(jīng)計算,)
取泵的效率,液壓缸的機械效率,回路效率為:
當工進速度為時,
當工進速度為時,
7.2 液壓系統(tǒng)的溫升
(只驗算系統(tǒng)在工進時的發(fā)熱和溫升)定量泵的輸入功率為:
工進時系統(tǒng)的效率,系統(tǒng)發(fā)熱量為:
取散熱系數(shù),油箱散熱面積
時,
計算出油液溫升的近似值:
,固合理。
結(jié) 論
目前我國液壓技術(shù)缺少技術(shù)交流,液壓產(chǎn)品大部分都是用國外的液壓技術(shù)加工回來的,所以發(fā)展國產(chǎn)液壓技術(shù)振興國產(chǎn)液壓系統(tǒng)技術(shù)。
不管人們有沒有意識到,科學技術(shù)已經(jīng)深深的影響著我們的日常生活,在經(jīng)濟社會發(fā)展扮演著不可或缺的角色??茖W技術(shù)在一定程度上也改變著我們的生活方式,改變著我們的文化。
正是因為科學技術(shù)具有如此的重要性,我們的國家領導人也在多種場合提出大力發(fā)展科學技術(shù)。我國在改革開放以后取得了很大地進步,步入了科技強國之林。但是,我們還應該認識到,我國很多技術(shù)都受限于發(fā)達國家。所以,我們應該奮起直追,迎頭趕上。
作為當前社會的一員,我們不僅應該認識到科技的重要性,還應該努力學習科學技術(shù),用科學技術(shù)來武裝我們的頭腦,具有獻身科學的勇氣和決心,具有用科學技術(shù)來發(fā)展全人類的博大胸懷。更重要地是,我們還應當教育我們的后代,要熱愛科學,尊重科學!
致 謝
在論文的寫作過程中遇到了無數(shù)的困難和障礙,都在同學和老師的幫助下度過了。尤其要強烈感謝我的論文指導老師—戴月紅老師,她對我進行了無私的指導和幫助,不厭其煩的幫助進行論文的修改和改進。另外,在校圖書館查找資料的時候,圖書館的老師也給我提供了很多方面的支持與幫助。在此向幫助和指導過我的各位老師表示最忠心的感謝!
感謝這篇論文所涉及到的各位學者。本文引用了數(shù)位學者的研究文獻,如果沒有各位學者的研究成果的幫助和啟發(fā),我將很難完成本篇論文的寫作。
感謝我的同學和朋友,在我寫論文的過程中給予了我很多相關(guān)素材,還在論文的撰寫和排版的過程中提供熱情的幫助。
參考文獻:
[1] 《液壓傳動》 丁樹模主編 機械工業(yè)出版社
[2] 《液壓與氣壓傳動》 左健友主編 機械工業(yè)出版社
[3] 《液壓與氣動技術(shù)》 張宏友主編 大連理工大學出版社
[4] 《液壓系統(tǒng)設計簡明手》 楊培元、朱福元主編 機械工業(yè)出版社
[5] 《液壓傳動設計指南》 張利平主編 化學工業(yè)出版社
[6] 《液壓與氣壓傳動》 游有鵬主編 科學出版社
n Appication of hydraulic AGC and
width control to a hot strip mill
D.Alan Davies,Project Sale Manager,Engineering and Construction Div. Davy Mckee (Sheffie id)Lid, Sheffieid, U. K.
THE Pohang Iron & Steel Co.(POSCO) No.2 hot strip mill at Pohang, South Korea,is a modern, three-quarter continuous mill built by Mitsubishi in 1980.The mill is 2050mm wide,has four roughing stands and seven finishing srands.The seven finishing srands have a combined power of 56,000kw with a maximum strip speed of 21 metres/s.Coil weight is up to 35.3 tonnes. Annual mil capacity is 3.56 million tonnes.
To improve width and gage tolerances,POSCO decided to install hydraulic automatic width contol (HAWC) on the last edger (E4) and hydraulic automatic gage control (HAGC) on finishing stands F4 to F7.
Davy McKee's contract was for the total ackage associat-ed with modernization of the mechanical and hydraulic systems,the computer-bassd AWC/AGC controls, new widthmeter, mechanical installation, commissioning and training. The new equipment was put into service during a 14-day shutdown in 1987.
n Outline of new facilities
A priority requirement was that the new equipment should be integrated with the existing facility in such a way as to permit reversion to conventional operation in a few seconds. Accordingly, hydraulic AGC and AWC cylinders were designed to withstand normal rolling conditions when in a collapsed state.
All of the control systems had to be in parallel with the existing systems (which were retained ) and existing operator's desk contromechanical system, depending on which system was selected.
The AWC system comprises short-stroke, single-acting cylinders (four in total )engineered between the ends of the horizontal screwa and the vertical roll chocks . These cylinders are servo-controlled, with a stroke speed of 100 mm/s (4 ips) to provide in -bar width control. (With the bar being typically 50 mm thick at this stage, only a limited amount of correction was expected.)
A new widthmeter after roughing stand R3 is used to give feed forward control signals to the edger E4 AWC with the existing widthmeter after rougher R4 providing bar to bar updating .
The AGC system on the last four finishing stands has short-stroke, single-acting cylinders located between the top chocks and the acrewdown thrust bearing/load cell units.These cylinders have excetionally high dynamic performance (28 Hz ,10 mm/s velocity ).
Becayse of the physlcal distance between the edger E4 and the finishing stands F4 to F7 ,separate pump sets serve each atra ,The hydraulic pressure is 275 bars, mineral oil,with a filtration level of 3 microns .
The new computer configuration compries a network of seven PDP 11/73 microprocessors linked by an Ethernet highway . An unusual feature of the system was the need to tap into the existing 64-way parallel communications link between the existing supervisory control computer (SCC) and the melplac plc's which perform the screwdown AGC, The tap had to be transparent to existing communication and of a high integrity . (Hence a warm spare stand by computer was included in the system .)
The required data for the AGC/AWC was extracted , serialized and communicated to the new system along the Ethernet , highway , This had the advantage of opening up the computer system to easier communications in the future , as new systems could be attached easily to the Ethernet .(A few months later , a further contract for ENCO heat retention panels and interstand water curtains was retention panels and interstand water curtains was received which required a further 11/73 miceoprocessor .)
n Mechanical/hydraulic design features
AGC cylinders ---Various components of the AGC cylinders and their assembly are illustrated in Fig . 4,5 and 6.
The cylinder design incorporates a single , low -friction seal that constests of a Teflon band mounted on the piston below a bronze , side trust ring . The base of the piston is chamfered to give a rocking surface when the cylinder is used in a collapsed state .It gives the necessary degree of freedom to absorb the normal deflections in the mill .
A hydraulic manifold is mounted to the front of each cylinder that includes the servo-valves.One of the position transducers is slightly discernible behind the small accumulator .Another position transducer is fitted diametrically opposite . The two signals from the transducers are averaged to provide a mean stroke signal .
The transducer package is shown in .The Sonymagnescale transducers with 1 micron resolution are hermetically sealed insode the brass bodies .
Three-stage servo-valves are employed (Moog 79 series ) .The third stage has its own built-in closed-loop position control . Each valve is nominally rated at 230 litres /min . Two valves are fitted to each cylinder and operate electrically in cascade , ie , as the drive signal to the first valve reaches saturation , it spills over to the second valve . They have a frequency response of 200 Hz . Cylinder parameters and performance data are summarized in Table I .
Dynamic performance was checked on a similar cylinder (890 mm dia compared to 960 mm on the POSCO mill ) with identical transducers , servo-valves , etc , installed on a mill housing equipped as a test rig . Steel blocks accurately represent the masses of the chocks and rolls , giving a truerepresentation of the mass-spring conditions in a real mill . The frequency resonse as a function of the rolling load is illustrated in , Loop gain is automatically adjusted by the software to optimize the dynamics .
One of the inberent features of a single-acting cylinder design is that the flow rate through the servo-valves and , thus , the cylinder speeds , is a function of the actual pressure in the cylinder . To prevent unnecessarily high speeds at the higher and lower sections of the range , simple software rules limit the electrical drive signals to the servo-valves ,effectively creating a stable and symmetrical velocity performance in both the extending and retacting directions , over the working range of the cylinder .
AWC cylinders --The AWC cylinders have a thrust bearing with spherical seating , embedded into the piston . Each cylinder is served by its own 3-stage servo-valve located nearby . The servo-valves and position transducers are interchangeable with the AGC counterparts . Performance details are also summarized in Table 1 .
Collapse force is provided by pull-back cylinders acting on the roll chocks . These cylinders are controlled to maintain a constant , low , pull-back force during the body of the bar , but increasing to a higher value to assist in achieving the tail end antinecking feature .
n Hydraulic systems --Hydraulic pumpsets are located in the oil cellars . The system serving the HAGC on stands F4 to F7 comprises a stainless steel reservoir tank with gravity feed to four axoal piston pumps ( three duty , one standby ) that deliver at 275 bars ( 4000 psi ) .
Filtration throughout is 1 micron nominal ( 3 micron absolute ) with a separate oil cooler/filter unit supplied by a separate recirculation pump , drawing oil from the tank , through the filter /cooler and back to the tank .
Accumulator manifolds with 38-litre , high -pressure nitrogen-filled accumulators ( that supply the transient demands mill stand . These accumulators are mounted as close to their respective cylinders as practically possible , to maximize dynamic performance .
n Contol system hardware features
One of POSCO's major concerns was the integration of the new computer systems without jeopardizing the existing system . (The existing system was to remain service and be available as a standby facility at all times .)
The 64-bit parallel interface between the existing supervisory setup computer (SCC) and the PLC ( MELPLAC) responsible for screw AGC could not be expanded or duplicated .
The solution was to interpose a PDP 11/73 with its standard digital I/O equipment betweent the SCC and the MELPAC to act as a communications link (Fig .9 ) . Its function was simple . It read-in the data from the a SCC as 64-bit data , stored it in memory and passed it immediately out again as identical digital output to the MELPLAC . The same exchange occurs in reverse order when data is passed back to the SCC . At each transaction , the 64 bits are decoded and converted into serial form for distribution to the remainder of the new systom . Such data would include all PDI and sretup information .
Because of the extreme concern for reliability in this exchange , a standby PDP 11/73 was included .When not in use , the standby machine is available as a software development facility for the entire new system .
These two machines were installed and commissioned approximately four months before the main shutdown when their function , operation and reliability were established prior to the main commissioning .In the main 14-day shutdown , the remaining conputer systems were brought on -line , although the AWC was given a lower priority than the AGC . The overall system configuration is shown .
Functionally , the HAGC for four stands were split between two 11/73 microprocessors to give a reasonable compromise between cost and utilization . Approximately 40% of the processor capability remains unused .
The roll eccentricity compensation (REC ) microprocessor can be switched to serve any one of stands F4 and F7 , whichever is seen to have the most significant eccentricity input . Afurther microprocessor could sasily be added in the future ( the REC function is described later in more detail ) .
The functions of the coordinating and logging microprocessor are evident ; it organizes the data flow between the various processors on the Ethernet and analyzes , stores and points out engineering and production data .
n Control system operational features
AWC system --The AWC system has two functions ;
l Reduce end crop losses by minimizing under-width ends .
l Improve width tolerances in the body of the bar .
Since the edger concerned is E4 and the bar is comparatively thin ( approximately 50 mm ) , little can be done to improve necking already created by the previous roughing /edging stands .Nevertheless , a small improvement can be expected by avoiding further worsening through stand E4/R4 . This is accomplished by preopening the edger roll gap a calculated amount and then swiftly closing onto the target width as the head end enters the edger . A similar procedure occurs at the tail end , when the gap is quickly opened a calculated amount .
The loci of these fast cylinder movements (eg , linear , expontial , parabolic , etc ) can be chosen by the setup computer , as well as the required gap adjustment velocity and stroke length .
Accurate tracking of the approach of the head and tail end is essential . This is achieved by special hot metal detectors coupled with bar speed measurement .
In-bar width control has two modes : BISRA gagemeter , and feedforward . Although the potential for the former mode of control ( which relies on the accurate sensing of instantaneous roll force to reduce mill stretch ) was always considered limited , due to the high frictional forces relative to the low rolling loads , it was , nevertheless , investigated . It was found to be unsatisfactory for the reason stated .
The feedforward mode , utilizing incoming width error variations detected by a widthmeter after stand E3/R3 , was successful . It resulted in exit width variations , measured after stand E4/R4 , within +2.0 mm for 95% of the bar length , as measured by the new widthmeter in this location . This instrument is used to give bar to bar width updating to maintain system calibration . However , it is not used for in -bar monitor feedback , because the transport distances involved are a significant proportion of the bar length .
n Hydraulic AGC--The operational features included in the hydraulic AGC system can be divided into those that can be considered as conventional and those that have a novel element .
Conventional AGC features include : absolute and lock-on BISRA gagementer modes for each hydraulic stand ; variable mill modulus ; oil film compensation ; draft comensation and absolute or lock-on feedback monitor .
Absolute and lock-on BISRA gagemeter modes for each hydraulic stand are selectable either automatcally by the SCC or manually .
The BISRA gagemeter action artificially stiffens the mill modulus . This occurs because the feedback from the measured roll foece causes the AGC cylinders to extend to compensate for mill stretch . The amount of compensation can be varied from zero ( ie , no gagemeter action ) , which leaves the mill with its natural mechanical stiffness , to 100% which , in effect , increases the mill modulus to infinity . Each hydraulic stand can be given a stiffness value ( 0 to 100% ) either from the SCC or manually .
Dynamic oil film compensation is obtained by cylinder movement to correct for dynamic changes in the backup roll bearing oil-film thickness , which varies as a function of speed and roll load .
Every gage correcting movement of the AGC cylinders results in a strip mass-flow change that alters the looper angle which , in turn , requests the stand speed to change . This sequence is anticipated and effectively shot circuited by direct speed trim signals sent directly from the AGC .
With regard to absolute or lock-on feedback monitor ,stand F7 etit x-ray gage can be selected to back in either mode . In the former mode , the system continues to make corrections until the target gage is achieved . In the latter mode , the head-end gage is accepted and maintained consistently for the remainder of the coil .
Novel AGC features include : auto-steering ; distibuted monitor feedback ; and roll eccentricity compensation .
Auto-steering , in which the tendency for the strip to steer to one side as a consequence of uneven heating across its width , is opposed by the control system . The roll force difference side to side is measured and fed to a functional representation of the tilt modulus of the mill stand ( the measured mill modulus characteristic when the roll gap is tilted differentially ) . The output of this functional block represents the amount of roll stack tilt that must have taken place to cause the force difference . The correction , similar to BISRA gagemeter , then restores parallelism to the roll gap and , hance , improves strip tracking .
Feedback from the exit x -ray gage to stands F4 , F5 , F6 andF7 is , in itself , conventional . However , the novel feature of this approach is that the distribution of correction is calculated to cause incremental force changes at stands F4 to F7 in direct proportion to the original roll force pattern calculated by the SCC . This minimizes the disturbance to profile and shape ( Fig .10 ) .Calculation of factors x , y and z take into account the following pattern ; required force distribution pattern ; percentage gagemeter set at each stand ; and calculated material stiffness at each stand .
The eccentricity of the backup rolls and bearings can cause a significant imprint in the material being rolled , particularly with gagemeter AGC , where the mill stands behave as if they were infinitely stiff .
Roll eccentricity is a complex function , generally different for top and bottom rolls , and from side to side . The resulting waveform is multivariable , changes with time and exhibits high frequency components ( up to 5th harmonic ) caused by bearing key effects .
The requirements for an effective automatic roll eccentricity compensation ( REC ) system are :
l Dynamic to follow the changing pattern .
l Cappble of isolating and identifying top and bottom backup roll effects , and the drive side and roll change side effects (ie , 4-axis operation ) .
l AGC cylinder response is sufficiently fast to respond to the REC system demands and counteract the disturbances .
A block diagram of the system is shown in Fig . 11 .
n Performance
Early equipment reliability problems , generally associated with the high shock forces created as this high-speed mill threads and tails-out , have been resolved for the most part with minimum loss of productivity due to the ability to revert almost instantaneously to the old system
The AWC system achieved its target of 95% bar length within +2 mm .
AGC performance for the coil body is well within + 0.050 mm (+ 0.002 in . ) . Occasional misses at the head end are attributable to mill setup . A new scheduling and setup computer system is to be installed .
Data collected over a 2-week period in March 1998 , covering approximately 3900 coils , showed that close to 96% of light gage coil lengths were within +0.035 mm (+0.00138 in . ) and that , for heavier gages (up to 6 mm ) , close to 95% of coil lengths were within +0.045 mm ( +0.00177 in . ) . ( These lengths refer to the coil lengths after exclusion of the first and last 5 metres of each coil . )
n Summary
The AWC and AGC systems , incorporating many new hardware and software features , with extremly exacting performance requirements , have met their objectives of improving strip quality .The potentially difficult area of interfacing with existing computer systems , while retaining their integrity , was accomplished through extensive planning and design .
n 對電控帶式銑床運用液壓
自動精度控制和寬度控制
戴維斯.艾倫博士,英國謝菲爾德股份有限公司工程與建筑部門項目經(jīng)理及營業(yè)主任。戴維.麥凱,英國謝菲爾德股份有限公司 。
在韓國南部浦項鋼鐵公司第二分公司的電控帶式銑床是在1980年建造的現(xiàn)代的,四分之三的連續(xù)的銑床。該銑床工作臺寬2050mm,能進行4次粗加工和7次精加工,其帶的最大速度 21m/s ,此時的總功率為 56,000kw.限卷重量是達 35.3噸以上。 該銑床的年產(chǎn)量為356萬噸。
為了改善加工寬度和精度公差, 浦項鋼鐵公司決定在尾末的修邊機安裝液壓自動控制(HAWC),并在精加工F4-F7處安裝液壓自動精度控制 (HAGC) 。
戴維.麥凱的任務是將現(xiàn)代化的機械系統(tǒng)和液壓系統(tǒng)連接在總體機器上,利用計算機建立 AWC/AGC的控制,實現(xiàn)新的寬度,機械的安裝,進行試車訓練。 新的機器在1987年在14 天的截止期間投入使用。
n 新設備的概述
一個先決條件是新的設備必須結(jié)合現(xiàn)有設備尋求一個方法,在很少次品的基礎上運用傳統(tǒng)操作實現(xiàn)反轉(zhuǎn)。 因此,液壓AGC和AWC氣缸設計成產(chǎn)生失穩(wěn)狀態(tài)時能夠抵擋正常的滾動。
所有的控制系統(tǒng)依靠被挑選的系統(tǒng)與現(xiàn)有系統(tǒng)保持平行,現(xiàn)有的操作員在實驗臺控制時,必須熟練地操作任何液壓系統(tǒng)和機電系統(tǒng)。
AWC 系統(tǒng)包含短行程,單作用氣缸設計在水平螺桿的后面與垂直滾動止動器之間,該氣缸是伺服控制的,以行程速度為100毫米/s提供在緩沖地址寄存器中的寬度控制,并且實現(xiàn)了頂部量器和尾部刀槽的效果控制。
在粗加工實驗臺R3后的一些寬度量具過去習慣于給正向反饋電傳送控制信號對修邊機E4進行自動寬度控制,現(xiàn)在現(xiàn)行的寬度量具在粗加工設備R4后,只需要面對面地調(diào)整。
自動精度控制系統(tǒng)在最后4次精加工中被設為短行程,單作用氣缸被定位在頂部止動器與螺桿下方的牽引軸承/載荷單元之間。這些氣缸具有異常的動態(tài)性能(28Hz,速度10mm/s).
由于實際距離在修邊機E4與精加工F4至F7之間,分離泵的總成裝配能供應到每一個地方。液壓設備需要壓力為275 bar,具有3微米過濾水平的礦物油。
新的計算機配置包含在以太網(wǎng)總線上連接7個程序數(shù)據(jù)處理機和11/73微理器處,系統(tǒng)的不同的零件需要被連接在現(xiàn)有的計算機監(jiān)督管理機構(gòu)(SCC)和可編程邏輯控制器(PLC)之間的現(xiàn)有的64位通訊端口上。再這之上有被透視的現(xiàn)有通訊和高速結(jié)構(gòu)(因此,現(xiàn)有的計算機系統(tǒng)包含有升溫設備站)。
給自動寬度控制/自動精度控制(AGC/AWC)的必須的數(shù)據(jù)被提取,并沿著以太網(wǎng)總線被連續(xù)的傳達給新系統(tǒng)。將來,如同新系統(tǒng)能簡單地被綁到以太網(wǎng)上那樣,這樣具有給計算機系統(tǒng)開墾更簡單的通信的優(yōu)點(兩三個月以后,更進一步的契約給ENCO加熱保留了展示板,并且,更多11/73微處理器必須的中間機座的云狀水紋被受到)。
n 機械/液壓的設計特點
自動精度控制(AGC)氣缸--自動精度控制(AGC)氣缸以及它們的部件的各種零件的視圖。
氣缸設計為單一的整體,低摩擦的封口的聚四氟乙烯萬能插孔帶被懸掛在青銅下的活塞上。當氣缸處于失穩(wěn)狀態(tài)時基準活塞被傾斜用于調(diào)節(jié)擺動曲面。在進行銑削時,反饋正常的偏差以達到所需要的自由度。
液壓管被安裝在每個氣缸的前面,包括伺服閥。其中一個位置檢測器在小型蓄力器之后稍稍可被辨別。其中一個位置檢測器在其正對面作配合使用。兩個信號從檢測器被平均地提供平均行程信號。
檢測器組件見。具有1微米分辨率的索尼magnescale 檢測器被密封在黃銅體內(nèi)。
第三類伺服閥被運用(穆格79系列)。第三類伺服閥有它自己的內(nèi)置組合式閉合環(huán)進行位置控制。每個閥的理論額定流量為2230升/分。兩個閥被配合每個氣缸安裝,并且被電線串聯(lián)運行。在工業(yè)工程學上,相當于傳動信號從最初的閥到達極限,并且遠遠超過第二類閥。他們具有200Hz的頻響應率響應,提供給所有28Hz的氣缸。氣缸參數(shù)和性能數(shù)據(jù)見表I。
其動態(tài)的性能的檢測是:將其安裝在相當于試驗設備的軋機機架裝備上,在一個類似氣缸上進行檢驗(浦項鋼鐵公司銑床上,直徑890mm與960mm比較),伴隨完全一樣的檢測器,伺服閥等等。鋼塊準確的表現(xiàn)了止動塊和滾子的質(zhì)量,給出質(zhì)量彈簧在實際銑削條件下的實際表達。頻率響應相當于載荷滾壓的作用,。環(huán)路增益通過動力學最優(yōu)化軟件自動校準。
一個單作用氣缸設計的固有特點是流動速率通過伺服閥被測定,因此氣缸的速率說明了氣缸的實際壓力。在氣缸的整個工作范圍內(nèi),在較高和較低區(qū)域的范圍內(nèi),為了防止不必要的高速率,用簡單的軟件規(guī)則把電傳動限制在伺服閥范圍內(nèi),并在延伸和收縮兩個方向有效地產(chǎn)生穩(wěn)定的,對稱的速度性能。
自動寬度控制(AWC)氣缸------AWC氣缸具有一個有球形座的止推軸承和壓入活塞。每個氣缸均可以通過它附近的自身帶的第三類伺服閥確定并使用。伺服閥和位置傳感器可與自動精度控制(AGC)相對的部位相互交換。性能細節(jié)見表1。
條 件
氣 缸
自動精度控制(AGC)
自動寬度控制(AWC)
內(nèi)徑(mm)
980
350
行程(mm)
30
5
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