A new design of the pressing unit is proposed, which uses a processing center for controlling the flow of pasta dough in the pre-matrix chamber of the optimal configuration. The internal configuration of the pre-matrix chamber is made in the form of a Venturi pipe, while the pipe is connected to the rod chamber by a confuser, and the diffuser is connected to the forming holes of the matrix, i.e. the mechanism for using the pre-matrix space for pre-compaction, plasticization and heating of the dough is implemented Laboratory experiments on the MIT-2 press machine for the production of pasta using a Venturi pipe gave positive results, and the expected economic effect due to increasing the productivity of the press, reducing specific energy consumption while improving the quality of products is about 20%.
One of efficient directions for pasta press designs modernization is installation of special conical-and-cylindrical inserts in the matrix wells in front of the dies having, like Venturi tubes, narrowing zones (convergent), expansion (divergent) and a cylindrical path located between them. However, rheological aspects of such method of forming tool modernizing in relation to pasta presses have not been studied, recommendations for structural elements calculation and design have not been developed. All this is a significant obstacle for using the method in engineering and industrial practice. The research purpose is to develop rheological models the pasta dough flow in the conical-cylindrical channels of convergent-divergent inserts and to evaluate with their help the impact of structural dimensions and rheological properties on resistance to pasta dough flow. Pasta dough was considered as a rheological complex nonlinearly viscous plastic material. In technical calculations contribution of shear strength was neglected and a rheological analysis was performed using the Oswald-de-Vila power law equation. Analytical dependences obtained make it possible to calculate the pressure drops in the convergent-divergent insert and its elements. Numerical modeling was performed and calculated data were obtained regarding the impact of dimensions of structural elements of the insert and rheological parameters of pasta dough on its resistance to viscous flow. The results obtained can form the basis of engineering and technological calculations in design of convergent-divergent inserts for laboratory and industrial matrices of pasta presses.
The introduction provides information about the state of the problem and substantiates the relevance of the research. The purpose of the work is to develop a methodology for calculating the relationship between pressure losses during the flow of pasta dough in channels with a stepped-variable cross section with the dimensions of the channel structural, as well as with the pasta dough rheological properties and the performance of device. In the methodological part of the work, the applied rheological model is described and a technique for mathematical modeling of power and kinematic parameters of pasta dough flow in stepped cylindrical channels is given. Due to the small contribution of the pasta dough shear strength to the total pressure loss, a rheological model of a non-linear-viscous medium is used, which is described by the power – law rheological Ostwald–de Waele equation. Neglecting the elastic deformations of the dough and the elastic change in volume, we assumed the condition of constancy of the volume and mass flow (productivity) for any cross section of the channel in each of its sections. In the main part of the work, analytical dependencies are presented that relate the magnitude of the pressure drop to overcome viscous resistance during the flow of pasta dough in channels with a stepped-variable cross section with the dimensions of the structural elements of the channel, as well as with the rheological properties of the pasta dough and the performance of the device. These dependences formed the theoretical basis for calculating method of the pasta dough flow parameters in stepped cylindrical channels. The technique was tested on the example of an industrial macaroni press matrix equipped with a system of stepped-variable channels in the pre-forming zone. The results of the research can be used in the design of new sizes of matrices for pasta dough molding as well as in the educational process in the training of food production process engineers.
Grinding of various materials is carried out in various ways: cutting, crushing, sawing, breaking, hitting. In the technological equipment of meat processing plants, grinding is achieved by a combination of several types of mechanical action. Each type of grinding is characterized by an average particle size, while large, medium, fine, fine, ultrafine (colloidal grinding) grinding is used. A block diagram of meat and meat products grinding has been compiled, which reveals the essence of the processes taking place and serves as the basis for justifying the improvement and creation of new working bodies of machines for more efficient meat grinding. The basic laws of the sliding cutting process are described, a mathematical model of the movement of meat raw materials in cylindrical channels of the knife grate is constructed. Analytical equations are obtained to determine the duration of grinding from the volume of finished products. A mathematical model of the knife grid of the emulsifier with a concentric arrangement of holes has been developed. The model allows you to get the same throughput capacity of the working surface of the grid in the horizontal plane. This model uses the regularities of the theory of preferred numbers.
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