The Study On The Control System Of The Metallographic Sample Cutting Machine Controlled Based On PLC

The Metallographic sample cutting Machine is mainly used to cut the metallographic sample and lay off or make slot in all kinds of metal materials, which is widely used in machine, metallurgy, automobile and aviation etc. As a kind of sampling equipment, the Metallographic sample cutting Machine is one of the important equipments in metallographic analysis, but the design and manufacture of the large metallographic sample cutting machine which can cut the big part directly is still blank in china .It is necessary to research and manufacture the large Metallographic sample cutting Machine in order to meet the needs of industrial development.The moving principle of the mechanism of machine of the cutting Machine and the process of the metallographic sample's cutting were researched in this paper according to the requirement of the metallographic sample. The control system of the cutting machine was designed according, to the Mechatronics' system design Principle. As far as the control system is concerned, the heart of the control system is PLC(programmable logic controller),the single-chip Microcomputer which serially communicates with PLC is used for display and input .PLC dedicates itself to data processing and controlling, the functions of the parameters setting and display are finished by the single-chip Microcomputer .After the control information is transmitted to PLC by the single-chip Microcomputer ,PLC controls one transducer and three step motor drivers according to the cutting mode and cutting parameters which were set by user, as a result, the worktable, the cantilever and grinding wheel move in phase and the task of cutting is completed.In order to resolve the Problem of serial communication between OMRON CPM2A PLC and AT89C52 single-chip Microcomputer, the Host Link communication protocol was researched, the communication interface circuit and communication program were designed in this paper, so the data exchange between PLC and single-chip Microcomputer was realized.A module of the single-chip Microcomputer with the functions of display and input was designed in this paper, which provided PLC with a person-machine intercommunication interface that was simple and practical, safe and reliable, low cost. Frequency conversion timing technology was adopted to control the asynchronism motor to attain stepless timing .By the means that the photoelectric sensor real-time sampled the roate speed of the grinding wheel and making use of the functions of high speed count and PID control of analogue variable, the closed loop control of the velocity of the grindingwheel was achieved, so the control precision of the velocity was improved, the flexibility of cutting different material was boosted up and the sample quality was guaranteed.The control system of the cutting machine that has designed in this paper has tow kinds of workings: automatic operation and manual operation.lt has four kinds of cutting modes: cut off workpiece once;cut off workpiece with advancing three steps and retreating one step;cut off workpiece layer by layer;cut off workpiece in series .The cutting ability of the cutting machine was enhanced ,so that cutting machine can cut off various sizes of parts efficiently.