Determining kinetic energy distribution of the working medium in a centrifugal disc finishing process—part 1: theoretical and numerical analysis with DEM method

Abstract

The centrifugal disc finishing process is an abrasive technique of mass machining, and it is very effective but very frequently time consuming. In this paper, a simulation of the centrifugal disc finishing process was presented in order to estimate the kinetic energy distribution of the working medium and to find its regions that make the process more efficient. Numerical results were obtained using an explicit method in the Ansys/Ls-Dyna program. Due to the fact that the physical properties of numerous objects in free motion need to be calculated in a simulation process, the discrete element method (DEM) was used. Results from the numerical simulations indicate that the velocity and energy of particles is variable in an axial cross-section of working medium. The article presents particle velocity distributions in the working chamber for various rotational speeds of the rotor. The typical changes in velocity in the function of time are also discussed. Statistical important functions of the average kinetic energy of the working medium and accumulated energy by machining surface have been estimated in respect to the rotational speed and machining time with a high value of adjustment coefficients. This article constitutes the first stage of research, which is continued in order to experimentally verify the results in the real process, as presented in the companion paper (Part 2: Experimental analysis with the use of acoustic emission signal).

Determining kinetic energy distribution of the working medium in a centrifugal disc finishing process—part 2: experimental analysis with the use of acoustic emission signal

“…Owing to the results of simulation studies [1], the authors knew what distribution should be expected and that it could limit the number of measurement points. However, in order to fully verify the results of the simulation tests and to estimate the functional dependencies with greater accuracy, it was decided to do measurements in the whole cross section of working medium, with the accuracy of 5 mm in the X and Y axes (assuming the workpiece size of at least 20 mm).…”

“…where m avg is the average media mass, v is the effective impact velocity, Tis the duration of force signal, A sensor is the force sensor The results presented in [4] show that during more than 85% of the finishing time, the sensor did not register a contact of any type (impact or non-impact) (Fig. 3).…”

“…This article is a continuation of the research, this time in an experimental form, on the problem of determining the kinetic energy distribution in the working medium during a centrifugal disc finishing process. A companion paper [1] describes the problem, a theoretical analysis, and results of numerical simulation research aimed at an identification of the variability of velocity and energy of the working medium. The numerical simulation tests, carried out with the use of the discrete element method (DEM), indicated that there are regions with different values of velocity and levels of kinetic energy in the working medium.…”

“…The state of the art in respect to estimation determining the kinetic energy distribution in the working medium by numerical method (DEM) has been reviewed in the companion paper [1], so attention is centered here on experimental verification of previous results.…”

“…More aggressive finishing conditions, characterized by greater impact velocities, caused more plastic deformation and resulted in more Almen strip deflection in shorter finishing time. The total kinetic energy was calculated on the basis of the value of effective impact velocity (recalculated from maximum impact force recorded by the sensor) [4]:…”