采用西門子數(shù)控直流調(diào)速裝置（6RA70系列），來控制圓盤電機(jī)的轉(zhuǎn)速，由PLC設(shè)定參數(shù)作為數(shù)控調(diào)速裝置的給定信號來改變瞬時流量。料流檢測由核子稱（JR2系列）信號與主皮帶信號換算得出，作為該圓盤系統(tǒng)的反饋信號。累計流量Q =K*T*∑G，G為瞬時流量，T為皮帶速度，K為比例系數(shù)。根據(jù)每一采樣時刻的瞬時流量計算出采樣時刻前一段時間（10S）的平均流量，將其與上位機(jī)流量給定值比較，得出偏差，然后進(jìn)行PID運算，得到控制量，后通過D/A模板輸出4~20MA的直流信號，作為直流傳動控制單元的給定值，改變電機(jī)的轉(zhuǎn)速，達(dá)到控制物料流量的目的。
3．2儀表控制
（1） 信號的采集與處理
利用Concept軟件*功能，針對不同的模擬量輸入信號和不同參數(shù)需要，分別編制了工程量轉(zhuǎn)換、數(shù)字濾波、偏差、上下限報警等各種信號處理的DFB，在控制程序中可直接調(diào)用這些功能塊。實現(xiàn)了混合料礦槽料位測量及上下限料位報警，混合料溫度的檢測，煤氣流量、氧氣流量的累計及瞬時顯示，煤氣與空氣壓力測量，低壓報警及低壓煤氣切斷，負(fù)壓測量與顯示，燒結(jié)料層厚度檢測。實現(xiàn)了抽煙機(jī)入口流量檢測，進(jìn)口廢氣負(fù)壓、溫度測量，電機(jī)軸承及定子溫度測量和超溫報警等。2） 點火爐溫度控制
點火爐燃燒控制是燒結(jié)工藝的重要環(huán)節(jié)，有比例自動控制和單回路控制兩種方式。當(dāng)選擇比例自動控制時，計算機(jī)以點火爐的爐溫為主調(diào)參數(shù)，以煤氣流量和空氣流量為輔調(diào)參數(shù)。由溫度調(diào)器的輸出作為煤氣流量調(diào)節(jié)器的設(shè)定值，溫度調(diào)節(jié)器的輸出經(jīng)配比計算（空燃比）后作為空氣調(diào)節(jié)器的設(shè)定值，然后進(jìn)行PID調(diào)節(jié)，實現(xiàn)煤氣調(diào)節(jié)閥和空氣調(diào)節(jié)閥開度的自動控制。當(dāng)選擇單回路控制時，根據(jù)現(xiàn)場輸入流量的設(shè)定值，與實際測量值進(jìn)行單回路PID計算，分別控制煤氣和空氣流量調(diào)節(jié)閥，分配其流量來控點火爐溫度。單回路控制圖見圖3。4 系統(tǒng)特點
（1） 實現(xiàn)了三電一體化。該系統(tǒng)現(xiàn)場檢測信號直接進(jìn)入PLC，電氣控制去掉了中間聯(lián)鎖。操作方式分為自動和機(jī)旁，取消了控制室內(nèi)操作臺、模擬屏及顯示表，改為CRT監(jiān)控，所有數(shù)據(jù)全部在上位機(jī)上顯示，用鼠標(biāo)和鍵盤操作。
（2） 建立了3臺燒結(jié)機(jī)的局域網(wǎng)。通過網(wǎng)橋使4#燒結(jié)機(jī)的PLC系統(tǒng)與3 5#燒結(jié)機(jī)的PLC系統(tǒng)實現(xiàn)數(shù)據(jù)交換，從而實現(xiàn)對燒結(jié)生產(chǎn)線的統(tǒng)一監(jiān)控。
（3） 故障報警及自動生成報表。當(dāng)出現(xiàn)故障時，監(jiān)控畫面將以警示色提醒用戶，同時控制柜發(fā)出電鈴報警聲，以便操作工及時處理。系統(tǒng)能實時地將歷史數(shù)據(jù)記錄在上位機(jī)中，對數(shù)據(jù)的查詢、統(tǒng)計和打印很方便，自動生成日報、月報及旬報。
period TK. (3) selected control system. The so-called control, is based on the analog regulator, the system control effect and the control effect of the analog regulator compared, its straight is the control system. Table 2 parameter setting table of extended critical ratio method. Thus the problem of setting four parameters is simplified to that of setting one parameter KP. Change KP, observe the control effect, until satisfactory, can determine KP value. Conclusion the above three methods of parameter setting can be used for reference by the engineers and technicians concerned. This paper introduces the design of the control system of the hot rolling mill's screwdown system and some problems needing attention. Key words: Press Down System AGC APC rolling table, plate thickness difference 1: Summarize Northeast Light Alloy Limited liability company according to the market demand, decided to carry on the technical transformation to the hot rolling mill, increases the mill aperture, increases from the original 300 mm to 400 mm, at the same time, the original hydraulic system, hydraulic control system, so as to improve the performance of hot rolling mill, improve product variety and quality. Two: The working characteristics of the original system hot rolling mill original reduction system is divided into electric reduction and hydraulic reduction two parts. The electric reduction is accomplished by a multi-speed control DC motor. The hydraulic down system is a hydraulic SERVO system. Because of the defect of the original system, the hydraulic down system is only used to adjust the roll gap, but not to control the roll down. Therefore, the original hot rolling mill screwdown system is actually only the electric screwdown screw positioning control system. The quality of the product is limited. In addition, there are some problems in the automatic control function of hot rolling mill, which can not be put into use. In production, the roller gap is set completely by manual operation. Three: the technical transformation must solve the question to increase the hot mill opening degree, enhances the rolling quantity, increases the product variety transformation
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