ACTA TECHNICA CORVINIENSIS - Bulletin of Engineering

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ACTA TECHNICA CORVINIENSIS – BULLETIN of ENGINEERINGProduction logistics is the term used fordescribing logistic processes within an industry.Also, the purpose of production logistics is toensure that each equipment and technologies isbeing fed with the right product in the rightquantity and quality at the right point in time.What materials, products, or information comeinto the activity? What materials, products, orinformation flow out of the activity? Qualityengineers use the D-M-A-I-C model (define,measure, analyze, improve, and control) todocument processes before beginning processimprovement. If processes are documented,another series of logical questions apply: Are theprocesses being followed? Are they withinacceptable control and performanceparameters? Are they outdated? Can they beimproved? Those are the questions whichdetermine the correlations between the logisticsprocess and the quality assurance.a different influence upon the quality and thesafety in the exploitation. Our approaches theissue of quality assurance of the rolling millsrolls, from the viewpoint of the quality ofmaterials, which feature can cause duration andsafety in exploitation. The quality assuranceresearch fields can be defined through thegeneral research area, through the differentexperiments effectuated in the laboratories, and,also, through the modern calculation programs,optimization technologies and the bettercapitalization of the manufacturing data (seeFigure 2).QUALITY ASSURANCE IN THE ROLL INDUSTRYThe manufacture of rolls (see Figure 1) is incontinuously perfecting, the requirements forsuperior quality rolls are not yet completelysatisfied, in many cases, the absence of qualityrolls preventing the realization of qualitylaminates or the realization of productivities ofwhich rolling mills are capable. Basic propertiesof rolls and properties of the material are twototally different sides of a problem and veryoften this difference is ignored. However, whenwe start to discuss about the rolls mechanicalproperties, we have to analyze the rolls materialor the roll-properties.Figure 2. Quality assurance research fieldsFigure 3. Quality assurance in rolling industryIn the rolling industry, the quality of the rolls isin directly accordance with the quality oftechnologies (defined by the casting equipments,materials, applied procedures, etc), and also, bythe quality of the manufacturing process(charging, melting, inoculation, ladle treatment,casting, cleaning, etc), which are presented inFigure 3.Figure 1. Casting technology of the iron rollsThe technological manufacturing process of therolling mills rolls, as well as the quality ofmaterial used in manufacturing them, can haveQUALITY OF ROLLS ASSURED BY MODELLING OFMANUFACTURINGIndustrial engineering is also operationsmanagement, systems engineering, productionengineering, manufacturing engineering ormanufacturing systems engineering, where asmost engineering disciplines apply skills to very322010/Fascicule 2/AprilJune /Tome III
ACTA TECHNICA CORVINIENSIS – BULLETIN of ENGINEERINGspecific areas, industrial engineering is appliedin every industry. Industrial engineers typicallyuse computer simulation, especially discreteevent simulation, for system analysis andevaluation. The computer is used to generate anumerical model of reality for the purposes ofdescribing complex interaction amongcomponents of a system.Starting from the principle of modeling process,used as necessary basic instrument, both inphase of conception, as well as in the industrialtechnologies analysis, is determined theoptimum regimes of the cast rolls, from the viewfrom chemical composition, as one as the mostimportant parameters of disturbance of themanufacturing process. The enunciation ofsome mathematically modeling results,described through a number of multicomponentequations determined for the spaces with 3 theand 4 dimensions, as well as the generation ofsome regression surfaces, of some curves oflevels, of the volumes of variation, of the lines ofoutlines of the volumes of variation of surfacesand the areas of variation of these, can berepresented and interpreted by technologistsand can be considerate diagrams of correlationbetween the analyzed variables. From this pointof view the project is inscribes in context ofscientific capitalization of the process and theindustrial technologies optimizations, on theway of the analysis and the mathematicalexperiment. The quality assurance through themodeling phenomenon is presented in Figure 4.Figure 4. Quality assurance through themodeling phenomenonThe character of the metallurgical processesoptimization is influenced by the complexpeculiarities of these, which take place into agreat number of variables (parameters) thatoperates independently or cumulate.For this reason, to analyze the metallurgicalprocesses is used, mainly, the statisticalfundamental methods that permit to drawnconclusions, from the observed values, about therepartition of the frequencies of variousparameters, about their interaction, aboutverification validity of certain premises, andabout the research of the dependencies amongdifferent parameters. However, the statisticalmethods of the metallurgical process analysesdo not solve a series of aspects regarding themode of establish the decisions for themanagement of the process. Thereof, parallelwith the statistical methods it was developedoptimization methods.The optimization of any technological processhas, as a base, a mathematical model. Thesearch for the best solution, for the truth,requests either to find, on the way of a study,definitive truths, or of relative valid truths, validonly in certain conditions, and which, in relationwith the definitive truths, include implicationsand errors.QUALITY OF ROLLS ASSURED BY THE LABORATORYEXPERIMENTSThe researches of durability in the exploitationof cast from cast-iron rolls, constitute ascientifically novelty, and experimentally definean important chapter from the thermal fatigue ofthe organs of machines in the movement ofrotation, in variable temperature mediums. Hotrolling mills rolls work the in the variablecompound solicitations, due to laminationprocess and which repeated to regular intervalsof time.All these phenomena, which are more or lessemphases depending on the type and typical ofrolling mills, are not taking into consideration inthe classic calculus of rolls. If the study of therolls resistance is extended upon their durability,we must consider the whole complex of tensionswith mechanic-thermal influences.The research on durability in exploitation of hotrolling mills rolls assures relevant conditions forthe appropriation of the research methods of thethermal regimes that are submitted the rolls or2010/Fascicule 2/AprilJune /Tome III 33
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