CLARIFICATION OF THE METHODS USED FOR CALCULATING POWER OF SIEVE SEPARATORS

Calculation of sieve separators power is usually done during their development. The goal of such calculations is to determine the power of driven electric motors. The imperfection of existing methods for calculating power of some types of sieve separators makes developers to use indicative methods to determine the gear power. For example, it is done using the method of specific energy consumption or the comparison method with parameters of similar equipment. These methods provide only indicative results, that is why the power of the installed electric motors sometimes even exceeds the needed one, so in such way it worsens technical and economic factors of the equipment. The methods for calculating power of flat-sieve separators moving progressive and invers or circular progressive have clearly determined sense and consider all energy consumptions of separators’ engine. The goal of the calculation of technological equipment and sieve separators in particular is to define the power of the electric motors. The imperfection of existing methods for calculating power leads to use in some machines of high power engines which selection is based on indicative calculations, for example, using a method of specific energy consumption or comparing with analogues. As the calculating methods depend on the law of working parts movement and their engine each example considered separately. In the calculation of the power of separators with flat sieve which are moving oscillatory the effective power required by the engine of sieve bodies equal to the sum of the average power required to drive the oscillatory moving mass; the average power that is needed for product overclocking; the average power required to overcome the friction force of the product in the sieve; the average power used to deform the suspension; the average power need to overcome the drag of the air environment. The current value of the power which is need to drive the oscillatory construction elements is determined considering the total value of oscillatory bodies mass; the weight and the amount of sieve bodies; the product weight on the bodies sieves; the weight of the oscillator; the frame weight. During a circular progressive movement of sieve bodies the power which is need to overclock the product mass on the sieve which are moving reciprocally is almost equal to zero, because the product is moving with stops during the all-time being on the sieve. This also refers to the movement of the product on the barrel sieves which are rotating, where parts change the direction of movement while they are slipping down and get accelerated again. The acceleration power in the separators with circled progressive motion of the sieves is equal to the kinetic energy of its circle oscillations. To provide the relative motion of the parts on the horizontal sieve surface which is making a circled progressive motion it is necessary that the difference between the centred inertial force and friction force to be more than zero.

Operational parameters and modes of rotary working body for harrowing crops

A rotary working body with evenly spaced needles along perimeter is a flat disk (rotating in longitudinal–vertical plane). The technological process of interaction with soil is that when rolling rotary disk in soil layer, needle is introduced into it, crushing and shifting soil in direction of rotation. The degree of soil loosening of freely rotating needle disk on axis in longitudinal–vertical plane depends on several parameters: diameter of a disk, number and shape of needles, speed of progressive motion, soil properties. There was made an analytical research of needle working bodies in terms of influence of sizes of disk and needles on process of their interaction with soil.

TESTING A PROTOTYPE FRICTION DRIVE TRANSMISSION

The article presents research on the mechanical properties of a drive system using an innovative mechanism converting rotary motion to progressive motion. The operating principle of the mechanism uses the friction-based transmission of drive from the motor to the drive shaft by means of two oppositely arranged unidirectional clutches. A side effect of such a solution utilized in the mechanism is the possibility of shifting the couplings while transmitting torque. The clutches were combined with a mechanism converting rotational motion to linear motion by utilizing friction between radial ball bearings and the shaft. This has resulted in an innovative mechanism for converting rotary motion to progressive motion, with the drive source being bound with a “friction screw” (a “slide” screw). A characteristic feature of this solution is the fact that there is no need for the nut to rotate in order to achieve progressive movement. Known solutions are based on a rotating nut and a fixed shaft system. The mechanism uses a fixed pitch nut, but it is possible to use a regulated pitch nut as a possible modification of the mechanism at a later stage of the system development. The main advantage of the mechanism tested is the possibility of uncoupling, which occurs when the maximum force transmitted by the nut is exceeded. This force is related to the friction force resulting from the pressure exerted by angularly shifted ball bearings on the drive shaft. The bearings are a substitute for the screw line in the classical ball screw mechanism. The research results presented in the article give an overview of the mechanical properties of the solution developed. The article also presents the influence of rotational speed and load on the mechanical parameters of the drive. The application of the described invention as the basis of the linear motion mechanism driving the tool of a surgical robot is a safe solution with unique and desirable characteristics.