CALCULATION OF PERFORMANCE FOR MECHANICAL DEBONING SCREW PRESSES CONSIDERING COUNTERPRESSURE

The article presents an analysis and formalization of existing methods for calculating the performance of different equipment for mechanical processing of raw materials with screw working body (grinders, mixers, pumps). It is noted that these methods do not consider the presence of counterpressure at the exit, where the reverse flow of the processed raw material is observed. Thus, the calculation of performance (e.g. grinders and pumps) is carried out more simply through the use of single empirical coefficient linking the design parameters, structural and mechanical properties of raw materials and the value of counterpressure with performance. It is shown that the existing calculation methods are developed for a homogeneous medium using Newtonian isothermal models and that their adjustment to experimental data was carried out by introducing the relevant empirical coefficients. These recommendations are widely used, but they do not allow the calculation of performance based on the counterpressure. The study was conducted mathematically by the method based on the technique of ?deployment of the screw channel? in the form of a rectangle covered by plate (wall of the working cylinder) and moving at a constant speed. The main attention is drawn to the assumption that the screw channel has the form of a rectangle, one side of which is equal to the depth of thread and the second side is equal to the pitch of thread. The equation linking volumetric performance with the geometric parameters of the screw, the formula for determining the volumetric performance of the reverse flow and the equation linking the actual performance of the screw with its geometrical parameters, rotation speed, counterpressure and the rheological characteristics of raw materials are developed. The value of performance loss for the screw press is calculated considering reverse flow of meat through the gap. For the first time, a method for calculating the performance of mechanical deboning screw presses is developed allowing to consider the effect of the gaps between the tip of the screw and the chamber, as well as the effect of ?sleeve-screw? gaps on the value of the performance loss.