Dynamics of air drive press for extracting grape juice at the stage of opening of raw materials

For pressing grapes, berries and fruits, basket, screw and pneumatic presses are used. They differ from each other structurally and have their advantages and disadvantages. Among the well-known designs of presses and drainage presses at the present time the most effective in modern farms are pneumatic presses for squeezing juice from grapes, berries and fruits. Of these, piston engines are quite complex in design and inconvenient in operation. Their design is constantly being improved, the pneumatic drive uses not only overpressure air, but also vacuum, but they have not been studied enough, the scope of application can be much wider. The proposed pneumatic press, in the body of which is installed a perforated basket for raw materials, pressed by a piston, above which there is a pneumatic chamber communicating periodically with a vacuum source, then with excess air pressure, which provides a pneumatic drive of the press. In this regard, when a vacuum is created over the piston, the compressed raw material loaded into the perforated basket is loosened. When overpressure air is supplied to the pneumatic chamber, the piston, when descending, compresses this raw material and ensures the squeezing of juice from it. The paper presents theoretical studies of the pneumatic drive of the executive bodies of the press in conditions of the constancy of its working volume at the stage of loosening of raw materials, which will simplify the process of squeezing juice from grapes, berries and fruits. The dependences are given for determining the duration of the main stages of the pneumatic drive of the press: pumping air from the pneumatic chamber until the formation of a working vacuum in it and the subsequent process of filling it with excess pressure air. Cyclograms of the press drive are given. The assumptions and simplifications made in it, taking into account all the cycles of the press, make it possible to calculate the main parameters without using special tables of integral sums, as provided by the accepted methods. This process will increase the volume of raw materials obtained.