MATHEMATICAL MODELING OF FRICTION FORCE AND FRICTION COEFFICIENT AT DEEP DRAWING PROCESS
This paper includes: experimental determination of process and blank holder forces at plate deep drawing, calculation of friction force and friction coefficient on the basis of achieved experimental results, determination of mathematical models Ft = f (SHP, φ, pd) and μ = f (SHP, φ, pd), as well as graphical simulations and analyses of achieved mathematical models. As substance for cooling and lubrication molybdenum disulfide and oil EP50 were used, while tribological conditions of contact surfaces were varied using phosphated and non-phosphated plate (EN 10027-1: DC04; DIN: RRSt14). Research results have shown that the best tribological conditions were achieved with molybdenum disulfide on phosphated plate, and the most influencing parameter is material deformation degree.
Experimental Friction Test by Sheet Metal Deep Drawing Process
Friction in forming processes is a very complex phenomenon depending on the workpiece material, tool work zone geometry, deformation degree and drawing speed, contact conditions quality, motion and lubricant type. The knowledge of intensity and distribution of the contact stresses and the friction coefficient in metal forming processes is the importance both from the theoretical standpoint of process analysis and the practical application. The direct contact stresses determining method has been applied. On the basis of this has been conceptually elaborated and designed a sensor for normal (pn) and tangential contact stresses (tauf) measurement by deep drawing process of sheet metal. On the basis of the measuring results it has been analyzed the dependence of the friction contact coefficient (mi) on the technological lubricant type (lambda) and degree of deformation (fi).
Numerical and experimental investigation on air distributor design of fluidized bed reactor of sawdust pyrolysis
Abstract An improved biomass conversion in a lab-scale fluidized bed reactor (FBR) is achieved by optimizing the air distributor orifice size and number. Two approaches for introducing air were numerically and experimentally examined. These included perforated plate and downward orifice sparger. 3 mm and 5 mm orifice diameters, and 7, 9 and 13 holes were simulated at flow velocities of 2, 4, 6, and 8 times the minimum fluidization velocity, Umf. The simulation results revealed that increasing the orifice number has a positive effect on gas holdup, particularly for the perforated plate, which showed a uniform distribution of bubbles. The sparger configuration produced larger bubbles sizes, which could lead to better recirculation of solid flux, while stagnant particle zones were observed at the lower section of both distributors. A pyrolysis unit is also inserted at the top of freeboard of the FBR. For perforated plate with 6Umf, the pyrolysis process achieved thermal and cold gas efficiencies of 82.91% and 52.03%, respectively, while combustible gases with 41.6%mol CO, 8.7%mol CH 4 and 2.17%mol HC, were obtained. For sparger pipe and 6U mf _sp, 35.33 ppm NOx and 111 ppm SO 2 were measured in flue gas from combustion process at bed region.