采用西門子數控直流調速裝置（6RA70系列），來控制圓盤電機的轉速，由PLC設定參數作為數控調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。根據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，將其與上位機流量給定值比較，得出偏差，然后進行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，改變電機的轉速，達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需要，分別編制了工程量轉換、數字濾波、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用這些功能塊。實現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，負壓測量與顯示，燒結料層厚度檢測。實現了抽煙機入口流量檢測，進口廢氣負壓、溫度測量，電機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工藝的重要環節，有比例自動控制和單回路控制兩種方式。當選擇比例自動控制時，計算機以點火爐的爐溫為主調參數，以煤氣流量和空氣流量為輔調參數。由溫度調器的輸出作為煤氣流量調節器的設定值，溫度調節器的輸出經配比計算（空燃比）后作為空氣調節器的設定值，然后進行PID調節，實現煤氣調節閥和空氣調節閥開度的自動控制。當選擇單回路控制時，根據現場輸入流量的設定值，與實際測量值進行單回路PID計算，分別控制煤氣和空氣流量調節閥，分配其流量來控點火爐溫度。單回路控制圖見圖3。4 系統特點

（1） 實現了三電一體化。該系統現場檢測信號直接進入PLC，電氣控制去掉了中間聯鎖。操作方式分為自動和機旁，取消了控制室內操作臺、模擬屏及顯示表，改為CRT監控，所有數據全部在上位機上顯示，用鼠標和鍵盤操作。

（2） 建立了3臺燒結機的局域網。通過網橋使4#燒結機的PLC系統與3 5#燒結機的PLC系統實現數據交換，從而實現對燒結生產線的統一監控。

（3） 故障報警及自動生成報表。當出現故障時，監控畫面將以警示色提醒用戶，同時控制柜發出電鈴報警聲，以便操作工及時處理。系統能實時地將歷史數據記錄在上位機中，對數據的查詢、統計和打印很方便，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