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本科生畢業(yè)設計 (論文)
外 文 翻 譯
原 文 標 題
AUTOMATING THE CONTROL OF MODERN Operated Melon Shelling Machine using Impact Technique of Manually and Motorized
Operated Melon Shelling Machine using Impact Technique
EQUIPMENT FOR STRAIGHTE
Operated Melon Shelling Machine using Impact Technique
NING FLAT-ROLLED PRODUCT
Technique
譯 文 標 題
現(xiàn)代化矯直軋制薄品設備的自動化控制
作者所在系別
機電工程學院
作者所在專業(yè)
機械設計制造及其自動化
作者所在班級
B13113
作 者 姓 名
李海俠
作 者 學 號
20134011309
指導教師姓名
賀俊杰
指導教師職稱
講師
完 成 時 間
2017年3月
北華航天工業(yè)學院教務處制
譯文標題
現(xiàn)代化矯直軋制薄品設備的自動化控制
原文標題
AUTOMATING THE CONTROL OF MODERN EQUIPMENT FOR STRAIGHTENING FLAT-ROLLED PRODUCT
作 者
YN Belobrov,
VG Smirnov,
AI Titarenko,
譯 名
百倫布若
國 籍
美國
原文出處
Mechanical Engineering Department, Faculty of Engineering and Technology University of Ilorin, P.M.B. 1515, Ilorin, Nigeria.Received 13 December 2008; Accepted 23 February 2009
譯文：
謝韋爾鋼鐵公司在2003年8月成功完成了新引進的規(guī)格為2800—5000米爾的直線式鋼板矯直機（平臺相關模型）。機器的主要設計特點如下：
l 每臺機器配備液壓緊固裝置(用于改善機器的動力學性能和調整的準確性以及更可靠地保持恒定的間隙)
l 每臺機器都有能在液壓缸的輔助下分別調節(jié)每根工作輥的機構(通過提供一種控制鋼板的曲率變化的方法來實現(xiàn)拓寬矯直范圍的目的)。
l 每個工作輥具有它自己的調節(jié)驅動(去除主軸之間的剛性運動學制約）
l 該系統(tǒng)平臺相關模型的輥軸是封裝在封閉箱（錄音帶）中的(便于維修,降低替換輥的成本)
l 這個模型有一個系統(tǒng),它可用于調整機器從九輥矯直方案轉變?yōu)槲遢伋C直方案，過程輥間的距離增加了一倍(這是為了擴大機器對板厚度的可允許范圍)。
因此,新的矯直機是一個多功能、復雜的機器,其包括一個可由數(shù)字和模擬信號控制的寬范圍、電驅動元件的液壓組件。整個復雜的機構可以分為兩個功能機體：主要的機體,包括直接參與矯直操作的機構(其夾緊裝置能獨立適應軋輥,調整組件以適應不同的矯直要求,可移動支線和主傳動裝置的上輥) ；輔助裝置(包括盒式替代裝置、主軸鎖定機構、輥軸支架設備冷卻系統(tǒng))。雖然平臺相關模型有大量的機制,運用現(xiàn)代液壓和電氣驅動，能夠在平臺相關模型和其運轉機構上幾乎完全的實現(xiàn)對主要和輔助機構的自動化控制操作。
下面描述的是薄板矯直機的特點以及自動控制系統(tǒng)的最重要的機理，同時對操作機理也進行了探討。
薄板矯直機的液壓緊固機構(HHMs)功能在于兩大系統(tǒng):調整系統(tǒng)；指定位置的維護系統(tǒng)。對控制系統(tǒng)和某些有效條件系統(tǒng)存在一定的要求。
在液壓緊固機構的調整系統(tǒng)、控制系統(tǒng),必須做到以下幾點：
l 液壓缸的同步運動保持，角偏轉到規(guī)定的限量以內(nèi)；
l 為適應新板的尺寸的最大調整速度；
l 保持高的定位精度的機制；
該控制系統(tǒng)在維護系統(tǒng)操作時具有以下要求：
l 使封閉箱的（錄音帶）附件保持穩(wěn)定，同時保證給料機的上輥具有較高的準確性；
l 當偏差出現(xiàn)時，最大限度地減少設備返還到約定坐標所需的時間(例如金屬板由于被矯直時而顯現(xiàn)出的彈力)。
同步需求。根據(jù)謝韋爾鋼鐵集團3號金屬板矯直機組得出的操作經(jīng)驗,調整機器時最不確定的因素是因為應用液壓缸兒產(chǎn)生的不均勻力。這種非均勻性是由平臺模型上大部分活動部件不對稱分布所引起的（特別是主軸裝配時的偏重效應）。伺服閥的“液壓零點”與“電氣零點”的相對位移也是一個因素。液壓缸的體積越小后者越重要。因此，給料機上輥的HHM的零點漂移是最敏感的。
也有其他因素的影響,同時性, 緊固機制的同步運行：
l 液壓缸上部分區(qū)域的摩擦力的差別源于成對零件的規(guī)模大小的組合差異，即使偏差非常的小；
l “彈起”差異特征和液壓供應渠道的慣性表征指標(由于液壓缸的伺服閥不同長度管的入口)。
因此,即使模型上沒有配置機械地保持液壓缸操作同步的裝置, 伺服閥的相同振幅信號的傳輸?shù)妮斎氩豢杀苊鈱е乱粋€嚴重危害機器的速差。
對降低及消除上述因素的影響,研制出一種對緊固機制進行電氣同步的算法。
包括四個緊固缸、四個平衡缸的封閉箱頂部的HHM,是為保證機器的靈活的調整設定所需尺寸的矯直差(按照板的厚度),并通過現(xiàn)有的準確性和遮蔽物上矯直力的符合缺乏來維持這個精度范圍。液壓系統(tǒng)的緊固機制設計是這樣一種方式,只有一室的液壓缸,是用來作為工作室。第二室總是與排泄通道相連。平衡力量被緊固氣缸克服時封閉箱降低頂端的。只有在氣缸平衡時封閉箱才提起。這樣的布置可以消除精度范圍在設備上的影響。
頂部的HHM的輥的支線由兩個液壓缸組成。當輥被提升的同時，輥降低和油液輸入桿腔，液柱塞腔被注入液油。
控制原則。特有電路如圖所示(圖1),來控緊固機制的液壓缸。伺服閥輸入端的控制信號（Xctl）是由一個比例-積分(PI)控制器傳遞的(為了提高靈系統(tǒng)的敏度,我們選擇了用瓣膜,以“零”觸發(fā))。輸入信號（錯誤信號Xerr）發(fā)送到控制器的輸入端后形成位置（Xcpt）和反饋信號的要點控制信號（Xf.b），后續(xù)信號是從所給液壓缸的直線位移軌距（G）接收的。
密封箱頂部的HHM的標定測量頭組成了平衡液壓缸(HCs)。氣瓶是安裝了這樣一種方式,他們的動作可以被認為是等于位移相應圓柱棒、與津貼為某些系數(shù)。支線上輥的HHM的測量頭組成了緊固氣瓶。
該控制器的不可分割的組成部分,僅在最后被激活時調整階段和穩(wěn)定規(guī)定的坐標。當位移超過一定閾值,PI控制器的功能是被一個比例(P)控制器的傳遞函數(shù)所代替的W(s)= k。因此,Xctl(t)= kXerr(t)。
當有工作中的輥子有非常顯著的差異時,這其中之間的關鍵控制點和反饋信號的區(qū)別(誤差)從直線位測量達到足夠大,這樣值輸出信號控制伺服閥的操作達到飽和區(qū)。在這種情況下,進一步位移、速度和同步動作的規(guī)定,這樣當誤差超過范圍時氣缸的同步移動變得不可能，這時Xctl大于飽和區(qū)的邊值問題(Xsat)。
通過減少k來解決特定的問題導致了在調整PSM時的速度損失和矯直機的操作中控制精度的降低。因此,為了保持控制信號到達飽和區(qū)當有大的位移、整個系統(tǒng)的設計，這樣的輸入端控制器并不是實際的所需值（Xrq),但增量(?X)是巨大的，k ?X < Xsat 這樣的狀況是令人滿意的。液壓缸的位置變化后，控制點的增加取決于?X的大小，其與相對于圓柱的運動方向相應的有最大的滯后量有關。調整的關鍵控制點維持現(xiàn)狀，直到所需要求和裝置的實際位置之間的差異小于其增量：Xrq – Xf.b < ?X。
然后控制器的輸入適應其增值Xcpt，相當于調整要求：Xcpt= Xrq。調整如此完成。
使用的原則是一步幾乎對所有的理想重復的因素而言，增加控制點使人們有可能同步運動的汽缸和設置的關鍵控制點以高度的準確性。獨特的調整機制工作輥。平板矯直機如此設計通過借助于V-belt驅動液壓缸動作來實現(xiàn)每個工作輥可以移動垂直。通過操作與比例伺服閥的控制來提供液壓缸的動力。線性位移測量器設置在每一個液壓缸上獲得輥的位置反饋信號。由于這些測量頭實際上是傳遞著液壓拉桿的位置信息而不是工作輥本身，在接下來的轉換中來得到坐標：kred驅使齒輪d動比;Xf.b是通過直線位移傳感器測量的柱桿位置。
因此,位置反饋電路反應了各項工作輥的姿態(tài)控制。圖1為電路圖。
控制信號產(chǎn)生采用PI控制器,它使得人們有可能達到了高度的調節(jié)系統(tǒng)的預測精度而不損失速度。
獨立驅動的輥子。這四種設計是基于使用獨立驅動的交流電機，其分別采用了不同動力反饋的變頻器。每一個單獨的驅動提供了以下一種優(yōu)于集中驅動:
l 由于在組件的機制中存在著線性工作輥和速度板之間速度不同的這種可能性；
l 如果一個乃至幾個驅動器出現(xiàn)故障，這臺機器可以繼續(xù)操作，但在這種情況下,相應的矯直輥的驅動將會被停止；
l 輥子的線性速度的可能性滾筒可單獨按照矯獨有的直板進給的實際速度；
l 輥子的線速度按照實際板材的速度進行更正成為可能,其速度可以進行一個修正或者作為一個初步調整措施；
l 這樣的修正作為一個初步措施（在測量和理論計算的基礎上)或在矯直機的實際操作中(在操作中獲得的數(shù)據(jù)和采用變頻調速器實現(xiàn)人工智能的基礎上)。
矯直機的主傳動為的矯直機九個矯直輥與兩個輔助輥。該驅動必須在操作中高度可靠,如果驅動不能正常工作甚至持續(xù)很短的一段時間，意味著軋機生產(chǎn)線的生產(chǎn)量可能會招致?lián)p失。
驅動所必須滿足的要求決定于機器整體的操作和設備的設計特點：
l 板材被矯直就必須在矯直機的下輥、上輥和相鄰輸送輥之間創(chuàng)造一個剛性運動耦合關系的；
l 板材應該承受到矯直機矯直操作中所導致的伸長塑性變形,伸長長度的不同增加是因為每個工作輥彎曲半徑的分化；這種情況導致了當板材移動快到PSM的末端時速度的不均勻增加；
l 必須使使用不同直徑的工作輥成為可能(這是必須的,比如說,由于不均勻磨損)；
l 負載輥應依照選擇而分化矯直體系；
l 反向矯直應當是可行的。
l 根據(jù)上述因素以及實際操作的體系板材矯直機正在被研制在這里,下列要求建立電力驅動:
l 廣泛的范圍內(nèi)規(guī)定的速度,包括啟動馬達在荷載作用下；
l 在逆向體系中的運行；
l 一個剛性的特點ω = ?(M)；
l 在保持規(guī)定的速度中有高度的準確性；
l 完全同步操作。
要求操作者顯示想要的位置的底部(5 -或9輥子l矯直);調整頂部和底部的間距;為工作輥子的個別調整設定坐標,選擇的矯直速度和方向;產(chǎn)生一個命令給機器開始調整到指定的機構。
這機器是自動適應所選擇的機構。調整完成后時,一個信號發(fā)送給控制面板顯示的坐標的狀態(tài)發(fā)生了變化,預示這些已經(jīng)達到他們的滾筒規(guī)定的工作速度。
在自動變量中、板式矯直機是為基礎調整的數(shù)據(jù)發(fā)送通過數(shù)據(jù)網(wǎng)絡從更高水平的系統(tǒng)。這些數(shù)據(jù)包括下列事項:
l 被矯直板的厚度;
l 鋼的組別 (物質比例的信息);
l Psm入口的溫度;
l PSM調整分幾個階段:
l 初步調整基于鋼板厚度及鋼鐵的種類,為冷軋鋼板(t = 20°C);
l 基于安裝在距psm50m的高溫計獲得的數(shù)據(jù)作進一步調整;
l 基于安裝在機器入口的高溫計做最終調整;
l 在自動變量控制輥輸送毗鄰機是轉向了控制。
系統(tǒng)的詩作為下一盤方法這臺機器。在這種情況,該盤直到及其調整完成才能進入工作區(qū)域。如果有必要板通過機器沒有矯直它,本機完全改變到運輸?shù)臓顟B(tài)。在這種情況下,頂端的橫木與黑盒將以規(guī)定的數(shù)量被提升并且輥子的速度被改變,以致于它的速度等于相鄰輥輸送線。
磁帶替換機制將被應用在輥子損壞的情況或有必要再研磨工作輥和后排輥,在這種情況下,操作者能控制輔助機制的運行:主軸鎖定機制、滾動式推車、底部的機制,鎖住底部錄音帶和車里的位置,推動車的液壓缸。
通過非接觸傳感器固定機器的位置。PSM控制系統(tǒng)。板式矯直機的控制要求一種功能強大的、高能力體系的開發(fā),該體系可以提供需要的控制精度與快速的運轉相結合。
該控制系統(tǒng)分為兩個層次:基層,和一個上層。診斷系統(tǒng)作為一個獨立的系統(tǒng)創(chuàng)建。第二個控制器對PSM的控制泵站進行控制。
基層的控制系統(tǒng)采用一種西門子系列S7的可編程工業(yè)控制器,而上層和診斷系統(tǒng)建立在標準電腦的基礎上。用于上層系統(tǒng)的計算機也作為PSM的控制面板。
不同要素的控制系統(tǒng)由兩圈連接的PROFIBUS網(wǎng)絡來連接，如圖3所示。第一個循環(huán)的功能是作為控制器、上層計算機、診斷站以及pump-station控制器之間的通信連接。第二個循環(huán)把PSM控制器和系統(tǒng)的功能元素連接起來（即頻率轉換器，線性位移量具和遠程輸入輸出模塊）。
基于以下準則，將控制系統(tǒng)的功能在基層和上層區(qū)分開來：基層承擔涉及從傳感器接收數(shù)據(jù)的機制安裝、從自動過程控制系統(tǒng)板上獲取即將矯直的信息、為執(zhí)行機構產(chǎn)生和傳輸控制信號（執(zhí)行器）的功能；上層承擔控制要點的歸檔以及監(jiān)控控制面板操作的功能。
以下特定功能是由基層的自動化系統(tǒng)來執(zhí)行的：
l 從上層系統(tǒng)獲取指定的矯直參數(shù)（輥子轉速，頂部橫臂的坐標，輥子相對于橫臂的坐標）；
l 處理參數(shù)，給執(zhí)行機構發(fā)送相應的控制信號；
l 從安裝在機制上的傳感器獲取信息來決定PSM是否正確安裝以及是否為矯直機操作做 好準備。
l 從安裝在機制上的反饋變送器獲取信息來估算控制措施；
l 分析傳感器讀數(shù)來決定數(shù)據(jù)的準確性；
l 與PSM泵電池站（PBS）進行數(shù)據(jù)交換，并發(fā)射站的運行參數(shù)到到上一級以進行顯示。
表1 平板矯直機的機器規(guī)格
參數(shù)
機器型號
LPM 2800
LPM 5000
厚度，mm
寬度，mm
長度，mm
板材最大屈服點，MPa
矯直速度，m/sec
矯直力，MN
矯直后鋼板殘余曲率(在整個厚度范圍),mm/m
7–60
1500–2700
from 5000
≤850
0.3–0.6
30.0
≤3.0
10–100
1500–4800
from 8000
≤1250
0.2–0.6
50.0
≤3.0
l 從上一級系統(tǒng)獲得初始數(shù)據(jù)進行自動校正和數(shù)據(jù)傳輸以便進行適當?shù)恼{整。
上一級自動化系統(tǒng)的功能如下：
l 在矯直管理系統(tǒng)中輸入數(shù)據(jù)以便隨后進行狀態(tài)選擇，并將信息錄入數(shù)據(jù)庫中；
l 從數(shù)據(jù)庫中手動選擇矯直狀態(tài)以選擇相應板材（這個由操作者完成）；
l 在從上一級系統(tǒng)中獲得信息的基礎上，從數(shù)據(jù)庫中自動選擇矯正狀態(tài)；
l 在矯正和盒子替換過程中進行手動控制機器表明機構定位的根據(jù)是傳感器和限位開關的位置讀數(shù)；
l 表明一個金屬板存在于PSM的工作區(qū)；
l 表明金屬板的溫度是由高溫計測量得到的；
l 視覺代表矯直系統(tǒng)和機器調整；
l 視覺代表機器結構和PBS的情況以用于診斷目的；
l 遠程輸入輸出模塊ET200是用來為未校準的驅動裝置供電。立柜中包括繼電器和接口，因為這些驅動器距離控制者有相當長的一段距離。該模塊的應用，使電纜長度的有效縮短成為可能。
診斷系統(tǒng)。高濃度的電器及液壓設備中包括類似PSM設備的一部分，這些設備與機器本身有一段距離，并且常常是難以到達的地方，這使之更難以為機器提供服務和尋找問題根源。為方便PSM的保養(yǎng)和維修時間的縮短，必須建立一個先進的診斷系統(tǒng)。
該系統(tǒng)是基于安裝在控制崗位的工業(yè)控制計算機。它診斷PSM各種機構，以及它的液壓和電氣設備的狀態(tài)。該系統(tǒng)可用于評估的自動開關的條件下，電機的溫度傳感器，線性位移計，當?shù)豍ROFIBUS網(wǎng)絡終端，電流，速度和電機的旋轉方向，以及其他設備和參數(shù).
診斷系統(tǒng)也可用于建立的PSM的操作協(xié)議。其文件包括即時的數(shù)據(jù)和錯誤的類型和發(fā)生故障的設備，機構的坐標，電機電流和速度，以及其他信息。
為了使控制系統(tǒng)更可靠，診斷臺的軟件和硬件與?控制系統(tǒng)的上一級相應的組件相對應。當電腦控制操作發(fā)生問題時，?PSM的控制功能可以轉移到診斷系統(tǒng)的計算機上面。
?結論，NKMZ曾與獨立國家聯(lián)合體（獨聯(lián)體）的創(chuàng)始伙伴合作，成功地引進了裝有現(xiàn)代自動化控制系統(tǒng)的板矯正機。
使用機器使人們有可能減少或者幾乎完全消除成品板質量對機床操作人員技能的依賴。?
控制系統(tǒng)，連同其方便的用戶界面，讓即使沒有受過專門培訓的人迅速掌握機器的操作。?高品質的產(chǎn)品的生產(chǎn)是在機器的運動機制保證下的確切結果?，并且其位置精確度也由其得到保證，這得益于具有比例控制和特殊控制算法的精密設備。?
此外，該機配備了先進的診斷系統(tǒng)，它也記錄關鍵?參數(shù)。該系統(tǒng)可方便機器的許多復雜的零部件的維修和保養(yǎng)。
原文：
The company Severstal’ completed the successful introduction of new in-line plate-straightening machines (PSMs) on its 2800 and 5000 mills in August 2003 [1, 2, 3]. The main design features of the machines are as follows:
l each machine is equipped with hydraulic hold-down mechanisms (to improve the dynamics and accuracy of the machine adjustments and more reliably maintain a constant gap);
l the machines have mechanisms to individually adjust each work roller with the aid of hydraulic cylinders (this broadens the range of straightening regimes that can be realized by providing a measure of control over the change in the curvature of the plate);
l each work roller is provided with its own adjustable drive (to eliminate rigid kinematic constraints between the spindles);
l the system of rollers of the PSM is enclosed in cassettes (to facilitate repairs and reduce roller replacement costs);
l the PSM has a system that can be used to adjust the machine from a nine-roller straightening scheme to a five-
l roller scheme in which the distance between the rollers is doubled (this is done to widen the range of plate thick-nesses that the machine can accomodate).
Thus, the new straightening machine is a sophisticated multi-function system of mechanisms that includes a wide range of hydraulically and electrically driven components controlled by digital and analog signals. The entire complex of PSM mechanisms can be divided into two functional groups: the main group, which includes the mechanisms that partici-pate directly in the straightening operation (the hold-down mechanisms, the mechanisms that individually adjust the rollers,the mechanisms that adjust the components for different straightening regimes, the mechanism that moves the top roller of the feeder, and the main drive); the auxiliary group (which includes the cassette replacement mechanism, the spindle-lock-ing mechanism, and the equipment that cools the system of rollers). Although the PSM has a large number of mechanisms,the use of modern hydraulic and electric drives has made it possible to almost completely automate the main and auxiliary operations performed on the PSM and the units that operate with it.
Described below are the features and the automatic control systems for the most important mechanisms of the plate-straightening machine.The operating regimes of those mechanisms are also discussed.The hydraulic hold-down mechanisms (HHMs) of the sheet-straightening machine function in two main regimes:the adjustment regime;the regime in which the specified positions are maintained.There are certain requirements for the control system and certain efficiency criteria for each regime.
In the adjustment regime, the control system for the hydraulic hold-down mechanisms must do the following:
l synchronize the movements of the hydraulic cylinders and keep the angular deeflection within prescribed limits;
l maximize speed in adjusting the machine for a new plate size;
l maintain a high degree of accuracy in positioning the mechanisms;
The control system has the following requirements when operating in the maintenance regime:
l stabilize the coordinates of the top cassette and the top roller of the feeder with a high degree of accuracy;
l minimize the time needed to return the equipment to the prescribed coordinates when deviations occur (such as due to the force exerted by a plate being straightened).
Need for synchronization. Experience in operating the plate-straightening machine in plate shop No. 3 at Severstal’ has shown that the most problematic factor in adjusting the machine is the nonuniformity of the forces applied to the hydraulic cylinders. This nonuniformity is due to the asymmetric distribution of the masses of the moving parts of the PSM (in particular, the effect of the weight of the spindle assembly). Displacement of the “hydraulic zero point” relative to the “electrical zero point” in the servo valves is also a contributing factor.The latter reason is more significant, the smaller the volume of the hydraulic cylinder.Thus, the HHM of the top roller of the feeder is the most sensitive to drift of the zero point.
There are also other factors that affect the dynamism,simultaneousness,and synchronism of the operation of the hold-down mechanisms:
l differentiation of the frictional forces on parts of the hydraulic cylinders due to different combinations of deviations in the dimensions of the mated parts, despite the narrow tolerances;
l differences in the “springing” characteristics and the indices characterizing the inertia of the hydraulic supply channels (due to differences in the lengths of the pipes leading from the servo valves to the hydraulic cylinders).
Thus, since the PSM is not equipped with devices to mechanically synchronize the operation of the cylinders, the ransmission of signals of the same amplitude to the inputs of the servo valves inevitably results in a speed difference that can seriously damage the mechanisms.
To minimize and eliminate the effects of the above-mentioned factors, we developed an algorithm for electrical synchronization of the hold-down mechanisms.
The HHM of the top cassette, composed of four hold-down cylinders and four balancing cylinders, is designed to ensure
mobile adjustment of the machine to set the required size of straightening gap (in accordance with the thickness of the plate) and
maintain that gap with a specified accuracy in the presence .
and absence of a load on the housings from the straightening force.
The hydraulic system of the hold-down mechanism is designed in such a way that only one chamber of the hydraulic cylinders is used as the working chamber.The second chamber is always connected to the discharge channel.The top cassette is lowered when the balancing forces are overcome by the hold-down cylinders.The cassette is raised only by the action of the balancing cylinders.This arrangement has made it possible to eliminate gaps in the positioning of the equipment.
The HHM of the top roller of the feeder consists of two hydraulic cylinders. Hydraulic fluid is fed into the plunger chamber when the roller is to be lowered and is fed into the rod chamber when it is to be raised.
Control Principles. Individual circuits have been provided (Fig.1) to control the hydraulic cylinders of the hold-down mechanisms.The control signal (Xctl) sent to the input of the servo valve is formed by a proportional-integral (PI) controller (to improve the sensitivity of the system, we chose to use valves with “zero” overlap).The signal sent to the input of the controller (the error signal Xerr) is formed as the difference between the control-point signal for position (Xcpt) and the feedback signal (Xf.b).The latter signal is received from the linear displacement gage (G) of the given hydraulic cylinder.
The gages of the HHM for the top cassette are built into the balancing hydraulic cylinders (HCs).The cylinders are installed in such a way that their movements can be considered to be equal to the displacements of the corresponding cylinder rods, with allowance for certain coefficients.The gages in the HHM for the top roller of the feeder are incorporated directly into the hold-down cylinders.
The integral part of the controller is activated only during the final adjustment stage and during stabilization of the prescribed coordinate.When the displacements exceed a certain threshold value, the functions of the PI controller are taken over by a proportional (P) controller with the transfer function W(s) = k.Thus, Xctl(t) = kXerr(t).
When there are significant differences between the displacements of the working rollers,the difference (error)between the control point and the feedback signal from the linear displacement gage reaches values great enough so that the output signal which controls the operation of the servo valve reaches the saturation zone.In this case, further regulation of the displacement rate and,thus synchronization of the movements of the cylinders becomes impossible as long as the error exceeds the value at which Xctl is greater than the boundary value for the saturation zone (Xsat).The limiting error–the largest error for which Xctldoes not reach saturation–is inversely proportional to the gain of the controller k: Xerr< Xsat/ k.
Solving the given problem by decreasing k leads to a loss of speed in the adjustment of the PSM and a decrease in control accuracy during the straightening operation.Thus, to keep the control signal from reaching the saturation zone when there are substantial displacements, the system was designed so that the input of the controller is fed not the actual required value (Xrq) but an increment (?X) of a magnitude such that the condition k?X < Xsat is satisfied.The control point is increased by the amount ?X after the position of the cylinder has been changed by the amount corresponding to the increment having the largest lag relative to the cylinder’s direction of motion. The adjustment of the control point is continued until the difference between the required value and the actual position of the mechanism becomes less than the increment:Xrq – Xf.b < ?X.
Then the input of the controller is fed the value Xcpt, which is equal to the required adjustment: Xcpt= Xrq.The adjustment is thus completed.
Use of the principle of a stepped increase in the control point makes it possible synchronize the movements of the cylinders and set the control point with a high degree of accuracy for almost any ideal repetition factor.
Mechanisms for Individual Adjustment of the Working Rollers.The plate-straightening machine is designed so that each working roller can be moved vertically, which is done by means of a hydraulic cylinder acting in concert with a V-belt drive.The cylinders are supplied with power from servo valves operated with proportional control.A linear displacement gage is built into each cylinder to obtain a feedback signal on the position of the roller.Since these gages are actually transmiting
information on the position of the cylinder rods rather than the working rollers themselves, the following conversion is performed to obtain the rollers’ coordinates:
Xrol= kredXf.b,
where kred is the gear ratio of the drive;Xf.b is the position of the cylinder rod measured by the linear displacement transducers.
Thus, a position feedback circuit is provided to control the position of each working roller. Figure 1 presents a diagram of one of the circuits.
The control signals are generated by means of the PI controllere, which has made it possible to achieve a high degree of accuracy in adjusting the system without sacrificing speed.
The individual drive of the rollers. The above-described design is based on the use of individual ac drives with motors of different powers fed from frequency converters. Each individual drive offers the following advantages over a group drive:
l greater reliability thanks to the absence of additional loads on the components of the mechanisms due to differences between the linear velocities of the working rollers and the speed of the plate;
l the possibility that the machine could continue to operate if one or even several drives malfunction;in this case,the corresponding rollers would be removed from the straightening zone;
l the possibility that the linear velocities of the rollers could be individually corrected in accordance with the actual speed of the plate;such a correction could be made either as a preliminary measure (on the basis of measured and calculated values) or during the straightening operation (on the basis of the data obtained from the frequency converters, which employ artificial intelligence).
The main drive of the straightening machine rotates nine straightening rollers and two housing rollers.This drive must be highly reliable in operation, since the fact that the PSM is installed in the mill line means that sizable production losses can be incurred if the drive fails to work properly even for a short period of time.
The requirements that must be satisfied by the drive are determined by the operational and design features of the machine as a whole:
l the plate being straightened must create a rigid kinematic coupling between the straightening rollers, the rollers of the housing, and the adjacent sections of the roller conveyors;
l the plate should undergo elongation during the straightening operation as a result of plastic deformation, with the increments in length being different on each working roller due to the differentiation of the bending radii;this situation leads to a nonuniform increase in the speed of the plate as it moves toward the end of the PSM;
l it must be possible to use working rollers of different diameters (this being done, for example, due to nonuniform wear or regrinding);
l the loads on the rollers should be differentiated in accordance with the chosen straightening re