Research On Intelligent Control System Of Numerical Control Roll Grinder Based On Knowledge

Rolling is a process where the metal is compressed between two rotating rolls for reducing its cross-section area. The rolls are expensive and consumptive tools. They are used to endure rolling force and make rolling material thin in roll grinding. There are some requirements for roll such as sufficient intensity, higher surface hardness, accurate structure and size, and roll shape and its grinding accuracy which can meet the product quality and proper rolling process.Roll grinding is a kind of special grinding technique which requires some special process technology. During the rolling process of profile and shape of plate, roll begins to wear. Worn roll must be ground in roll grinder. Roll grinder is a large type precision machine tool, and it is a key device in manufacturing metal plate, strip, foil material enterprise. Hence it is very important to ensure and improve product quality.In recent years, with the rapid development of metallurgy, paper making, rubber, plastic, printing and dyeing industries economy, roll diameter is up to 3000mm, roll weight is also close to 300 tons and its geometric accuracy isμm degree. Meantime, with the coming of heavy load roll grinder, the requirement of roll grinding technique is more and more high. With the lasting development of NC, traditional roll grinder is introducing in the direction of NC roll grinder. NC technology is not only kernel technology of modern NC roll grinder, but also the base of automation, flexibility and integration of it. Under the action of NC technology, traditional manufacturing industries are being converted to information manufacturing stage, system architecture is also converting from closeness to openness. Openness is an important characteristic of modern control system. This will make plentiful software and hardware resource of computer technology to be employed in a greater degree, simultaneously make precision on-line sensor and measurement system to be integrated. Intelligence technology can help the system to acquire knowledge from practical experiences, provide process planning strategy for roll grinding, and ultimately realize the intelligent roll grinding.Intelligence will be a main characteristic of modern NC roll grinder. Because roll grinding is very complex machining process with too many influence factors, the final quality and performance of grinding is deeply correlated with specialist knowledge, previous grinding practical experiences. Because there is strict quality requirement in complex rolling process of plate, roll profile and its grinding accuracy must be strictly controlled, this requires knowledge of roll grinding and rolling process. Knowledge is used to reveal information combination on regularity of thing. It contains relation between information and decision, and is used to directly or indirectly solve problem. With the development of knowledge economy, information integration is converted to knowledge based processing method. Research on knowledge based engineering (KBE) in the field of grinding will be a main trend. KBE system obtains knowledge and practical experiences of field specialist by means of a series of processing methods on knowledge, selects reasonable modeling method and language of knowledge, computer knowledge, and selects adequate knowledge strategy to make intellectual reasoning, deduction and decision according to given production model. The control system can make intellectual decision and control for roll grinding by combination of knowledge based method and mathematics model based method.Because NC technology is developing towards to practicality technology, special system integrated with manufacturing technology is more applicable to high efficient and quality machining of special product. General NC system can not include machining technology of part. It is a control system which suits various general parts. Due to many influence factors such as specialist knowledge, roll technology knowledge and. plate rolling knowledge etc, traditional ideals using general NC system is not effective in this special manufacturing field. Hence roll grinding technology integrated into control system is most important characteristic of intelligent NC roll grinding system in this dissertation.Modern intelligent control system should adopt intelligent NC standard. Due to traditional ISO6983 NC standard has many disadvantages such as bad flexibility, one-way data flow from CAD/CAM/CNC, postprocess, no spline data etc, new intelligent STEP-NC standard is built by ISO. STEP-NC has many advantages such as bi-directional data flow between CAX and CNC etc, and it can improve interchangeablity and flexibility of information. Because of obvious parameterized characteristic of roll shape, STEP-NC ideal is adapted to efficiently realize CAX/CNC of roll in this dissertation.Though NC technology has developed in general NC control system for many years, it indicated slow development in roll grinding field. Because of nonlinearity, randomicity, uncertainty in grinding process, there are many insufficiency facts in roll grinder. At the present time, many problems about existing NC roll grinder at home and abroad need to be solved, such as creation of roll shape, expression of roll shape model, interpolation strategy of roll shape, compensation for grinding wheel wear, wheel dressing method, grinding of alternating speed, optimization of grinding parameters, historical data traceability of roll shape and grinding process data, intelligent fault diagnosis. At present, adjusting the grinding process strongly relies on the operator's experience and skill. The grinding is one of the key technologies that constraints some elements of advanced technology development.Intelligent system used in the field of abrasive processes usually draw on one or more of the following approaches such as KBS, ES, FL, NN, GA, ACO and model based method etc. The most common operation researched is external and internal cylindrical grinder, robotic IC grinder, screw grinder, surface grinder and creep grinder. At present, related literatures on roll grinding system are seldom reported.The paper is supported by the production, teaching, and scientific research project of Science and Technology Commission of Shanghai Municipality (05dz11c04). In this paper, aiming at the problems existing in the roll grinding, the theoretical and experimental study were conducted for roll grinding, principle of roll grinding, influence elements of roll grinding, principle of grinding wheel wear, principle of wheel dressing. Some mathematical model were built such as the dynamic model of roll grinding, contact length between grinding wheel and roll, grinding force, grinding power, compensation for grinding wheel wear. Architecture on NC roll grinding intelligent control system integrated with roll grinding process based on knowledge was built. Some key techniques and strategies were also studied, such as multi-objective optimization and decision of grinding parameters based on knowledge, on-line intelligent grinding wheel dressing method based on dual channels, intelligent roll shape based on STE-NC ideal and its spline interpolation strategy, adaptive optimization control for grinding of alternating speed etc In this paper, in order to obtain better quality of roll grinding, intelligent theory and methods such as KBE, ES, GA, FL, NN etc were introduced into roll grinding control system.This study is of great theoretical and practical value to improve quality and accuracy of roll grinding. Research result also provided new ideal for roll grinding in home and abroad, this will be helpful for producing the remarkably socioeconomic benefit.