Tham khảo tài liệu 'friction and lubrication in mechanical design episode 1 part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | The Contact Between Rough Surfaces Ì05 The results as generated from the simulation for cutting conditions covering the practical range of applications are used in a regression analysis to obtain the best fit for the equation parameters c ky and kị. The values of the system parameters of Eq. for the case of a chuck mass A of 34 kg and machine structures with stiffness K greater than 108 N m were found to be independent of K and are only dependent on the uncoupled tool natural frequency 0 . All the simulated results were curve-fitted to give the following equations c 1 -e 29 lli 3 kị 1 - k2 1 - e-f -29 - 1 kj - 1 - e - -29 0-1 k4 - 1 - c- 29 515 where ã natural frequency of tool assembly Hz These equations are applicable for the following conditions when is greater than 108 N m 61m min V 305m min rev f rev mm d mm mm r mm THE REAL AREA OF CONTACT BETWEEN ROUGH SURFACES Analytical studies and measurements show that the real area of contact between surfaces occurs at isolated points where the asperities came together. This constitutes a very small fraction of the apparent area for flat surfaces Fig. or the contour area for curved surfaces Fig. . For the case of steel on steel flats the real area of contact is in the order of cm2 per kilogram load. This indicates that pressure on the microcontacts for any combination of materials is constant and is independent of load. The interactions between the two bodies at the real area are what determines the frictional resistance and wear when they undergo relative Ỉ06 Chapter 4 Contour Area Real Area Figure a Contact of flat surfaces b Contact of spherical surfaces. b The Contact Between Rough Surfaces 107 sliding. Even in the case of a Hertzian contact the pressure distribution is not continuous. Due to surface roughness it occurs at discrete points and the force between the bodies is the
