Proceedings of SerbiaTrib '13

olling. Rolling resistance of radial motion of f thecylinder at flat surface was investigated in the paper[9]. Tested results showed that the coefficientofrolling friction depends on the speed of cylindermovement. At low speeds of cylinder, thecoefficient of rolling friction increases duee toincreasing of substraterate of deformation.Forhigher speeds, however, the coefficient of rollingfriction is reduced, thereby loweringthe area off thedeformed surface. The maximum force f of frictionat the initial moment of slip has been investigatedon rubber-metal frictionpairs under conditionss ofconstant compressivedeformation of the rubberduring transition from the high-elastic to the glassystate questioned A. I. El'kin et al [10] in the paper.Filled butadiene-nitrilee rubber compounds werestudied in the temperature rangefrom +200 to−50°C. The temperature dependence of themaximum force of friction has a sharply expressedmaximum near the glass transition temperature. . Asthe temperature falls, the force of friction at firstincreases, inaccordancewith the molecular-kinnetictheory. As the temperature continues to fall, inn thetransition region maximum force off friction beginsto rise more sharply owing to a sharp increasee inthe volume-mechanicalfriction component.Thefall in the maximum force of friction below theglass transition point associated with a decrease inthe deformed volume of rubber due to shrinkageand with the reducedd mechanical loss factor.Persson et al [11] study the sliding friction forviscoelasticc solids, e. .g., rubber, on hard flatsubstrate surfaces. Consider first the fluctuatingshear stress inside a viscoelastic solid which resultsfrom the thermal motionof the atoms or moleculesin the solid. At the nanoscale the thermalfluctuationsare very strong and give rise to stressfluctuationsin the MParange, which is similar tothe depinning stresses which typically occurr atsolid-rubberr interfaces, indicating the crucialimportance of thermal fluctuations for rubberfriction on smooth surfaces. Developed a detailmodel which takes into account the influencee ofthermal fluctuations on the depinning of smallcontact patches (stresss domains) at the rubber-thesubstrate interface. The experiment led toconclusion that the amplitude of the surfaceroughness has a very small effect off friction slidingrubber. Theeffects of carbon and cellulose fiberson the tribological characteristicsof rubber-basedfriction materials examined Akbar et al in his paper[12]. Friction tests realized with different slidingspeeds anddifferenttemperatures, with theexaminationn of the microstructureand mechanicalproperties of the surfaces in contact. Experimentalresults showed that carbon fibers had a minor effecton the coefficient friction, but that increase wearresistance. Shanahan et al [13] investigated ithemechanism of adhesion that occurs inthe contacttpair rubber andd hard metal rolling bodies. The highhdegree of adhesion can bee apparent even at roomtemperature if the contact time and pressure reachsufficient values. Based onn obtained results it wasdetermined thatt energy, which is dissipated duringrolling, refers not only to the influence thattaccompanies histeresis h adhesive separation, butalsoto the losses caused by loadingwith largecylinder. The nature n of friction between the rubberrandthe solid substrate is very important for manytechnical applications. Friction of rubber issignificantly different fromm the friction betweenhard substancess such as metals and ceramics. In thepaper [14] it was proved that the tire hassignificantly favorable friction characteristics.In order too optimize the construction wereeperformedlargenumberof theoreticalconsiderationsand preliminary ideas were done fora detailed review and analysis of the literature thattexamines this issue. Research is based ondetermining the transmission of torque from thespecial device on marine winch drum, which isdone by means of friction between rubber andmetal.2. CONCEPTUAL DESING OF ROTATINGEQUIPMENT FOR WELDINDAn important aspect of implementing of anyautomated system to the manufacturing process isits price. Because of that, design should beanalyzed in detail determing which parts of thetechnical systemm are not meaningful to t automate.To define the appropriate general design, projectstarts with the technicall requirements of theproduct, discusses designn solutions of existingproducts with similar functions (Figure 1). Drive ofrotary positioner shown is realized by two electriccmotors and gears, because speed and variable speeddrive is required. The principle of operation of theelectric motor which w drivess pieces of the t structurerequires ensuring synchronization of movement,which is seriouss theoretical and practical problem.Figure 1. Rotating positioner34213 th International Conference C onn Tribology – Serbiatrib’13