Вестник МГТУ. 2020, Т. 23, № 3.

Вестник МГТУ. 2020. Т. 23, № 3. С. 224-236. DOI: 10.21443/1560-9278-2020-23-3-224-236 From design conditions we use a pump-compressor o f the 2NVR-5DM type. Electric motor power N = 0.55 kW, rotor speed n = 1430 rpm. We determine the performance o f a vacuum meat mixer when working in a vertical position according to the formula Q = 60X a ^ - ^ = 60 x 0.7 ° Л 5x1100 = 232 kg/h, T 30 (9) where a - the filling factor o f the capacity o f the meat mixer in the mixing mode (a = 0.6-0.7); V- the volume o f the mixing bowl of the mixer, V = 0.15 m3; q - the specific gravity o f minced meat, q = 1100 kg/m3; T - the cycle time, min T = ti + t 2 + t 3 = 9 + 12 + 5 = 26 min. ( 10) where ti - the duration of loading the working bowl, min; - the duration o f the mixing process, min; t3 - the duration o f unloading o f the working bowl, min. From the experience o f operating meat mixers of a similar design: ti = 9 min, = 12 min, t3 = 5 min. We accept for the calculation T = 30 min. Checking the selection of the geared motor for the torque on the output shaft when the mixer is in vertical position is necessary. We find the power required to overcome the resistance o f the horizontal blades. The resistance coefficient is found by the formula К = q 2 x g ( 11) where у - the coefficient depending on the shape o f the blade and the ratio o f its height and length. Due to the high viscosity o f the liquid, this coefficient is taken in the range o f 1.2-1.5. We take у = 1.5, then K = 15 x11° ° = 84. 2 x 9.8 We find the surface o f the blade (Fig. 3) f = (fa + fb + fc) X ri, where ri = 0.295 m. Fig. 3. Scheme for calculating the geometric parameters of the blade Рис. 3. Схема к расчету геометрических параметров лопасти ( 12) (13) fa = a x cosa = 0.054 х cos70° = 0.054 x 0.342 = 0.0185 m; fb = a x cosa = 0.022 х cos45° = 0.022 х 0.7071 = 0.0156 m; fc = a x cosa = 0.06 х cos75° = 0.06 х 0.2528 = 0.0156 m; f = (0.019 + 0.016 + 0.016) x 0.295 = 0.051 х 0.295 = 0.015 m2 Moving speed o f the blade is determined by the formula 2 x n x г x n V = max 60 (14) (15) (16) (17) (18) where n = 12 rpm - the number o f blade revolutions in min. 231