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.
NUMERICAL AND EXPERIMENTAL METHODS FOR DETERMINATION FRICTION COEFFICIENT
In this paper is analyzed and determined the coefficient of friction between the wheels of the vehicle and asphalt. Coefficient of friction is gained through practical measurements and theoretical methods. It is set changes between values gained through practical measurements and theoretical methods. Coefficient of friction is presented as a system of forces applied in engineering, which is described in a system of forces acting on a rigid body. The model for determining the coefficient of friction is built based on a rigid body and to elaborate was taken the vehicle tires which are loaded with a testing mass, with different physical parameters of roughness (asphalt, concrete, gravel road congestion, ice, etc). Analyzed changes of static coefficient subjected to rigid body forces, changes the dynamic coefficient of friction, geometric constraints, values calculated with mathematical method through variables. Measurements were made with gauge forces applied to enable more accurate measurements and also are seen changes of values depending on the solid foundation for testing. Keyword: Values of coefficient of friction, static and dynamic friction coefficient, the system of displacement forces.
Modelling And Optimization Of The Tool Geometry For Deep Drawing Of Sheet Metal
By means of modelling of the deep drawing process of axis-symmetric workpiece a mathematical model of drawing force process, has been defined the optimal range of roundness radius of the die, the optimal range of degree of strain and the optimal technological lubricator. The mathematical models, which show dependency of deep drawing force and the parameters of drawing process, the geometry of tool and the tribological conditions of the plastic forming, were estimated by regression analysis. The results of performed research indicate that the mathematical-experimental modelling can be successfully used to define the form of the tool work zone, the parameters of tribological processes and the technological parameters of the deep drawing process.