Radu Ilea, Cornelia Tonea, Gheorghe Drăgoi, Daniel Popa, Lorin Piloca
The flat sieves are often used in agricultural processes of seed separation at harvester reapers, as well as at seed conditioning. The operation of separation of seeds is realized due to the vibration of flat sieve. Generally, the phenomenon of vibro-transfer is essentially influenced by the material behavior, characterized by composition, humidity, adherence, nature etc. In the first approximation, the experiences shown that the material can be schematized by a simple material particle which moves with friction on the vibrating surface. There are analyzed displacement regimes of particle by forward sliding, back sliding and detachment. Because of velocity discontinuity which appears as consequence of friction between particle and plan or of dropping on plan in the case of detachment, vibro-impact motion regimes appear. That is why, for the study of motion, there are applied the specific methods, concerning the vibro-impact regimes. It must underline that in some processes of vibro-transfer, motions with detachments can appear and also, droppings of particle on the vibrating plan. This kind of regimes is of the nature of vibro-impact phenomena and forms a special domain of study. There are taken into consideration only vibration displacements with sliding on the vibrating plan, which have vibro-impact character because of the discontinuity of friction force. The motion investigation of particle on flat sieve is analyses by the aid of motion parameters: the angle of gradient of the shaking surface, the angle between the direction of the shaking and the surface, the sliding friction coefficient, the angular velocity etc. It is supposed that the vibrating plan executes a vibration translation according to rsinwt law. As a rule, at a certain moment, the particle begins to slide on the plane, from the repose position, forward or back. The moment when the forward sliding begins is noted by t 1 and for the beginning of the back sliding by t 2 . It is specified that these moments correspond to the condition that the acceleration to be null. If the expression of the acceleration is annulled, are obtained the motion laws. Forward, the differential equations of the movement are established and the mathematical apparatus are developed in order to obtain the charts which emphasize and limit different possible dynamic regimes. The obtaining of this charts is computerized, therefore, with the help of a computer program it is possible the specification of the parameters which leads to realization of some optimum dynamic regimes. The work have a real interdisciplinary character because requires large knowledge of mechanics, agricultural machines, mathematics and computer programming.
flat sieves; vibrational transport; particle; relative motion; optimum parameters
Presentation: oral