THE GRINDING MECHANISM ON A KNIFE CENTRIFUGAL GRINDING MACHINE

The article presents a methodology for calculating the force effect on a fibrous suspension of working bodies in a centrifugal grinding apparatus. The aim of the research is to calculate the force per tooth of an inertial body at different speeds of rotation of the rotor, to determine the effect of the circumferential speed of movement of inertial bodies on the grinding process of fibrous semi-finished products. The article discusses the mechanism of grinding on a centrifugal knife grinding apparatus, determines the tangential shear forces at the contact of the grinding satellite knives with the grinding bowl knives, determines the effect on the fiber of rolling friction forces and sliding friction forces when the grinding satellite knives come into contact with the grinding bowl knives, as well as the effect of specific pressure at the point of contact of the satellite knives with the grinding bowl knives under the influence of inertial forces. Based on the research results, it is scientifically substantiated that the forces arising at the minimum of the considered values of the rotation speed of inertial bodies are sufficient to break the fiber when using this installation for grinding fibrous semi-finished products. An increase in the speed of rotation of the satellites causes a positive change in the physical and mechanical characteristics of the finished castings.

A New Device for Characterisation of the Drainage Kinetics of Fibrous Suspensions Under Gravity

Gravity dewatering of fibrous suspension is one of basic technological operations in paper production process. Although there are numerous methods to determine dewatering of such suspensions, none of them can measure undisturbed flow of removed water. In the paper the idea and design of a new apparatus for the determination of drainage rate of fibrous suspensions is presented. The apparatus differs from other known devices by minimisation of filtrate flow resistance in the outlet part of the equipment. In the second part of the paper measurements of the drainage rate have been presented. The flow resistance of the fluid through the bottom wire screen in the device was determined. The calculated flow resistance will be used in the developed model of dynamic drainage of fibrous suspensions, which will be discussed in our following paper (Przybysz et al., 2014).