بررسي فرايند نورد سرد ورق تحت رژيم روانكاري مخلوط با امولسيون آب و روغن

چكيده انگليسي :

Analysis of Strip Cold Rolling Process in the Mixed Lubrication Regime with Oil Water Emulsion Behnam Haj Shir Mohamadi b hajshirmohamadi@me iut ac ir January 10 2014 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Dr M Mashayekhi mashayekhi@cc iut ac ir Abstract Growing need of industry for the precise and high quality metal sheets has made researchers study cold rolling process in more detail Among these studies lubrication of cold rolling is an interesting field for researchers On the other hand Oil in water emulsions are widely used in rolling industries as a lubricant due to its cost cooling ability non flammability and low adverse environmental impact characteristics whilst providing good rolling lubrication Therefore it is essential to investigate its behavior in cold rolling process In this study application of the extended Reynolds equation for emulsions proposed by Yan and Kuroda to the mixed film lubrication relation introduced by Chang and Mrsult has led to a model for cold strip rolling process with Oil Water emulsions For the sake of achieving a more realistic model front and back tensions which are normally applied to the strips are considered The model involves solving equations in two zones including inlet and work zone which consists of solving otal pressure and asperity contact ratio accompanied by a second order ODE to find the lubricant film pressure The extended Reynolds th equation order Runge kutta approach Neglecting the elastic deformation of the work roll may reduce the contact region between the strip and the work roll which causes an underestimation of the actual force and torque Thus the well known Hitchcock relation is used to consider the effect of the flattening deformation of the work roll during rolling By solving the equations all the boundary conditions are satisfied in five loops including a trial and error loop to correct the roll radius according to Hitchcock method and another loop to determine forward slip at the exit plane Going through solution procedure rolling force torque pressure distribution and oil concentration are found alongside with other unknown parameters Results show that oil concentration has a major effect on these parameters in high rolling speeds compared with minor influences in the low speed region The film thickness and pressure grows with oil concentration while rolling force and torque decrease By utilizing emulsion instead of pure oil as lubricant it is found that neutral point will shift to the inlet in high front tensions while it tends to approach to the outlet in low tensions In accordance with the experimental observations in EHL this model predicts formation of an oil pool at the end of inlet zone in low speeds which decrease in size by increasing the rolling speed The oil pool size depends intensively on the initial concentration of emulsion that means in high initial concentrations larger oil pool forms at the beginning of work zone causing entrance of pure oil to the contact region of roll and strip Keywords Cold Strip Rolling Mixed Film Lubrication Oil in water Emulsion Lubrication with Emulsion Extended Reynolds Equation

حاج شيرمحمدي، بهنام

بررسي فرايند نورد سرد ورق تحت رژيم روانكاري مخلوط با امولسيون آب و روغن

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