Research And Design Of Surface Plates Flatness Detection System

More and more surface plates technology has been used in electronics products, aselectronic technology developing. The surface flatness of the palte products is the importantfactor of it quality.So, General Administration of Quality Supervision, Inspection andQuarantine promulgated the rules of the flat test procedures.Making the standard of theparameter of flatness parameters, and setting the maximum flatness error and thecorresponding level of accuracy of plate. It proposed and implemented a more economicaltesting program of surface plates according to the verification procedures of state andcombining the requirement of the actual market detection accuracy, to achieve the goal ofon-line mass detection.Proposing the design project of surface plates flatness based on mixed-signal system on achip-based smart C8051F MCU. The system was according to the standard of diagonal spotevaluation rule, using the principle of minimum conditions for the evaluation method, andused the SOC system-chip MCU core intelligence collector to collect the data of measuredplates through the multi-channel eddy current displacement sensor. Making up the industrialgrade232network by Modbus protocol, to finish the completion of handshakecommunication with the PC. The PC used LabVIEW to design program-controlled interface,and collect the data of plates, refer and manage the historical information, combined withAccess database technology.The major work is as the following aspects:(1) Researching the assessment criteria of surface plates flatness. Selectting the eddycurrent displacement sensor by the maximum error reference of actual detection andmeasuring the plate in accordance with rules of distribution measurement. Selectting theappropriate base plane of the plate, using12-point distribution to measure, and calculating thedeviation of all measurement points relative to the ideal plane, the difference between themaximum and minimum value was the flatness of the surface plate. After assessing the errorby diagonal rule, the raw measurement data changed into the data relative to the referenceplane. Assessing again in accordance with the principle of minimum conditions to checkingflatness measurements.(2) Putting forward an intelligence collection system byt he highly integrated SOCsystem-chip MCU as the core. The system used sensors to collect the displacement signal ofplates, used multi-channel analog switch to strobe analog signal input, and blowed up thesignal by the instrument’s front-end circuit. Data acquisition system had analog/digitalconverter ADC, digital/analog converter DAC, voltage comparators, programmable gainamplifiers, and UART communication interface, to design a single-chip intelligent acquisition. System used the Modbus protocol RTU transmission mode to achieve the communicationwith PC.The systerm check entire system for news content by CRC in order to prevent theerrors during the transmission.(3) Using the visualization graphical software LabVIEW to design programmableinterface of flatness detection system on PC. Gating system acquisition channels, andcollecting zero voltage which channel gated. Setting serial communication parameters,collecting voltage data of gated channel, and converting the voltage detection value based onacquisition value. Setting pass criteria flat detect, and determining flat plane degree qualifiedstatus. Make testing data statistical by multiple acquisitions. Calling the Access database tostore real-time detection data, and seeing about qualified conditions of history test case andthe query specify the date of the test panel data. Deleting or printing the data and otheroperations handling. Design interface of user login and password to enhance detection systemsecurity.(4) According to the flat flatness detection system required to complete function test.Constructing function generator, six and a half DMMS, PCI GPIB interfacecontroller-automatic precision calibration system, to improve the measurement accuracy.Using Agilent33220function generator to imitate potential voltage signal by12road eddycurrent displacement sensor. Collecting the zero voltage value and the simulation of platedetection voltage value, and showing verification and detection qualified status indication.According the request to inquire the history test data, detect the management function ofsystem database. The testing process ensure the the normal work of the operation of thedetection system.Currently, plate electronic products develop much more fast, and people pay moreattention on the quality detection. By the cost and precision of the demand, this system notonly has high price ratio, and has perfect database management and other functions. It alreadyhas been used in the line successfully at present.