Study And Application Of Soft Sensor Technique In Plate Rolling Process

The dependence of measuring instruments is extraordinary high for plate rolling process, but producing condition of which is so formidable that all kinds of interference will affect the accuracy of measuring instruments, if there is an error or accuracy decreases in measuring instruments, the normal manufacture of plate will be affected. This paper combines with actual manufacture of national certain 3500mm plate mill, exploits soft sensor system platform of plate processing, combines with all kinds of field measuring instruments and plate production technology, measures on-line controlling parameters by rational soft sensor models and exploits artificial immune networks for fault diagnosis, so it will improve the process control accuracy and product quality. The specific research contents were shown as follows:(1) Data acquisition and handling platform was established. Study the data communication of real-time data between basic automation system and soft sensor system by OPC technique and stream Socket technique, exploit data acquisition system which used oracle 10g as database, built up data handling platform, which deal with random error data, misdate, noise data and rough data, and it supplied a reliable mass data platform for soft sensor system.(2) Product size parameters soft sensor method of plate rolling process was built. The impact of steel plate velocity by forward slip and steel dragging as well as the influence for steel plate volume changing by thermal expansion and iron scale were analysed, lateral flow regular pattern of work piece at spreading stage was studied, the current change tendency when steel dragging happens and changing regular pattern of head width when steel plate tongue shape deformation happens were considered, and then high accuracy on-line soft sensor models of length, thickness and width were deduced. A forward slipping extent conception was presented which evaluated the slipping phenomenon quantitative based on the changing of current. At the same time it put forward soft sensor on-line correction technique as race division and race correlation, which devised the race by thickness, width, temperature and steel grade, and then optimal division factor of soft sensor model is obtain by using association degree model which calculates the association degree of races. On-line actual application shown that the deviation between thickness soft sensor value and average of manual measuring could be controlled within 0.2mm, deviation of width soft sensor could be controlled within 8mm.(3) Deformation resistance soft sensor method of plate rolling process was built. The influences for deformation resistance by factors such as chemical composition, rolling temperature, strain rate, deformation and so on were analysed, for the residual strain affectes resistance to deformation greatly as to control rolling process, the influences to residual strain by Nb and grain dimension of austenite were also it analysied at the same time, and the residual strain model and deformation resistance soft sensor method by RBF neural networks were built up, by comparison of soft sensor value and laboratory value at condition of different steel grade and strain rate, the accuracy between measuring value and experiment value of this method was almost anastomotic.(4) Studies on rolling temperature inference controlling based on soft sensor technique were carried out. The influences to temperature changing of plate by major factor such as heat radiation, convection, high-pressure water descale, thermal conductivity of roll contact, rolling plastic work done and so on were analysed, and the relationship between blackening coefficient and plate thickness was analysed, then mathematical models in which thickness of iron scale changes as time going on were built up, which dynamic corrected the heat transfer coefficient of heat radiation as the changing of iron scale thickness. The confidence interval of pyrometer measured temperature and designs inference estimation implement by using partial least square solution were calculated, which considered pyrometer with highest confidence as conference, inference and estimates measured values of other on-line pyrometers and determines their measuring deviation.(5) Measuring instruments fault diagnose system based on soft sensor technique was built. The system structure and function survey of on-line measuring instruments were introduced, and the relationship among measuring instruments datas were analysed. Fault diagnosis technique of artificial immune networks was used based on real-time data of instruments, which built up by amicable numbers evaluation, individual density evaluation, calculation of motivation degree, immune selection, clone, dissociation, clone rejection and swarm update and so on. From actual application it shows that there was a better effect to fault diagnoses of on-line measuring instruments of this system and it supplied a reasonable guiding action to rolling process controlling and instruments fault diagnose.Research findings above have been applied to some national plate mill, which solved several puzzles in production. Plate production soft sensor technique was also an extensive research field, whose theory and method should be abundant, developed and sounded further, and many problems should be solved further.