| 1. The aims and meanings of the taskThe friction material plays an especially important role inautomobile and almost motor vehicle brake system.With automobileindustry avail driving,it affords increasing at synchronous speed inselling space for friction material not only in appoint provider marketbut also service market .A lot of material are harmful to environmentand the operaters.To fit the need of competing market and humanenvironment protect consciousness strengthen,Some friction materialfactories in rather size begin invest to research auto metagesystem.This task is about more research work after we helped a frictionmaterial factory of SHANDONG Group Co. research friction material autometage system.The task offers solve precept and theory base with friction materialtrade development of our country.At the same time ,it has referencepurpose for else trade metage material research such as metallurgy,construct material,curative trade and so on.2. Basic design ideaThe system is consist of PLC,transducer to correspond auto producecourse;brainpower megate controller to accomplish weight signalmagnify,filter,modulus conversion and real time pass data to epigynycomputer with COMport. The epigyny computer accomplishes displayingand data disposing,And that industry-control computer is directions forproducing chemicals manage and control system core.The epigyny computer except communicating with hypogyny computerto accomplish the need of controling,and should display the workcondition dynamic currently,optimizing directions for producingchemicalsand managing consultation and so on .So epigyny computersoftware design coach idea is operating easyly ,controllingreliablyand full function . The system chooses VB6.0 as epigynycomputer software flat,It can easy edit amity application interface,also have apowerful data-base function ,and can deal with directionsfor producing chemicals data very well, it should be easy to carrythrough system setting or changing , At the same time currentdisplaying object run status and hopper material weight ,can satisfythe request for auto metage weight system epigyny computer appliancesoftware flat as well.3.The task brief introduction3.1 The basic form of system hardware The system adopted industry-control computer made of yanhua actingas control core,Chose OMRON Co. CPM2AH Programmer Logic Controllerto control electromagnetism-valve,motor . The COMport of OMRON Co.CPM2AH type Programmer Logic Controller may very easyly communicatewith PC. In order to improve efficiency,six hoppers can work at one time,additional repeat-check metage , The system needs seven metagecontroller.Thinking of the scalequality and price and companycontinuous development, A suit of brainpower metage controller wasresearched by ourselfbeingmade up of 89C51 singlechip computer addingamplifier,A/D conversion circuit,data transmission circuit.The amplifier choose a sort of minitype and cheap photo electricitycoupling isolation amplifier ISO 100, as ISO 100 volume is small,maladjustment voltage is depress,excursion is little,frequency-rangeis wide,leak current is little and cost is low enough ,satisfying manyindustry and measure-control equipment require.Because the presssensor signal is small,it should be plus about 100 again preamplifierAD620 magnifying ,then to isolation amplifier.ICL7135 is abroadpopularity singlechip integration 4 digit half double integral A/Dconvertor at present internal market. As ICL7135 have 4 bit halfprecision,automatism zero,automatism polarity output,single referencevoltage ,dynamic word bit scan BCD code output ,automatismmeasurement range control signal outputand low price .It can be fitfor the system.The metage controller need current magnifying 0-40mAfaintness signal coming from press sensor signal , magnifying ,filtering and transmit 89C51,The metage controller pass MAX485 chipto realize singlechip distance communication with PC, According tothe signal gathering weight PC setted arithmetic to control D/Aoutput and transfer order to PLC,PLC control feeding material motoraction sequence,hopper door on-off and material vehicle advance andback off according to epigyny computer's order. Commonly computer mainboard all have one to four COMport,howeverthe system except PLC even have seven weight gather systems passingCOMport communication with computer,choosing a piece of MOXA oneentrain eight COMport to resolve the problem. According the experience and message researched automatism metagemachinein the past,feed material motor only adopts single speed orrough feed and precise feed at two speeds.Precision is difficult toassure,especially each transducer of the system wants to control fourfeed material motors,moreover every material's humidity,conglutinateand proportion are different ,so it needs a program to setupcurrent change the speed of feed material motor's---Appointedtransducer voltage. D/A conversion moulding board is designedwithMAXIM company MAX5270 as core. MAX5270,eight channels thirteen bitD/A. After through electricity output state can be set up with programfitting for the system.3.2 The system software function design VB6.0 are chosen as Epigyny computer softeare flat,exceptcommunicating with hypogyny computer,but controlling ,alsodisplaying the current dynamic work state ,optimizing directionsfor producing chemicals,managing consultation function and so on. In addition according to control object characteristic,The systemadopts integral separate model PID arithmetic.For one separate modelPID controller, The first are scale and integral effectthat strengthenthe system adjust function,the second is integral effect,tilleliminate static error.In computer control system integral separatecontrol method is adopted,this can obviously reduce control overrunand transition time of object parameter,improving adjust capability . The PID control equation is follows: μ(t)=K [e(t)+T 1 T P ∫e(t)dt + 0 T D (de(t)/de)]The system include not only tradition feedback closed loop systemcontrol function,but also utilizing forecast error expiation valuey( to correct every kind material e(k)i(viz. the error of theory k)igiven value comparing with output value ,And add to k-1 scale panbefore i kind material ,using this sum value ∑( k)(i ?1) to adjust themasterial metage rough,precise setting value.On running course,Epigyny computer ceaseless measure the last scale pan masterialdynamic error e(k-1)i,according to the value is big or small and thedynamic error ofthe two scale pans that one is next to the other tochoose polarity,changing return coefficient KO ,to sure that surgedoesn't appear in the metage course.In this course the errorconvergence speed can automatically adjust,making dynamic errorconvergence course in good state.At one time according differ kindmaterial to choose motor speed.and improve the precision of the systemdynamic control.4.Experiment result analyse Practice carry out the friction material full automaticallymetage weigh system comparing with handcraft. Strongpoint as follows: (1)High batch stability. (2) High material-weigh efficiency 。 (3) Small pollution . (4) Precise directions for producing chemicals secrecy. (5) Precise directions for producing chemicals recur. (6) High automatization grade . With going deep into consumer use and investigate continuously,the... |
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