Double piston alternating action pressing apparatus
BACKGROUND OF INVENTION 
     Technological Background 
     The object of the invention relates to a press apparatus having a double piston and alternating action. 
     It is adapted to exert an adjustable pressure on various products and more particularly grapes, to extract the juice without grinding the bunches, or stems and seeds. 
     Until the present time, grape presses have generally been utilized which include a helical screw shaft and a blocker so as to avoid having the grapes turn with the screw. However in these types of presses, the blocker, by rubbing on the helical screw, causes the grapes to be crushed with the grinding of the bunches and the seeds. 
     SUMMARY OF THE INVENTION 
     The apparatus according to the invention overcomes these disadvantages by replacing the compression screw by a double piston system which makes it possible to modulate the pressure in rapid sequence and in slow sequence by successive impulses with pressure on the assembly of the mass uniformly distributed over all of the surfaces. 
     The apparatus according to the present invention is constituted by the combination of a rapid advancement feed piston and a second telescopic piston having low and stepwise advance. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the annexed drawings, given by way of non-limiting example, one embodiment of the object of the invention is shown as follows: 
     FIG. 1 illustrates the apparatus seen in its entirety in elevation and in longitudinal cross-section; and 
     FIGS. 2, 3 and 4 illustrate the various phases of the pressure cycle according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The horizontal presser, as shown in FIG. 1, is constituted by a sealed container 1 within which is concentrically positioned the perforated cylindrical cage 2. This cylindrical cage 2 is directly connected to the charging funnel 3. It is blocked at its rear portion 4 by a pivotable door 5 and at its front portion by the double plate pressure piston 6, 7. 
     Plate 6 is mounted at the end of the telescopic shaft 8 of double action jack 9. Double action jack 9 includes double shaft 8, 10, which performs the first push on the grapes by means of plates 6 and 7 connected to one another. The second push on the grapes is performed by shaft 8 and plate 6. 
     Grapes are fed into press 2 by the funnel 3. The grapes fall into the feed chamber 11. Thereafter, under the effect of rapid advance piston 9, the grapes are brought into pressure chamber 12, as shown in FIG. 2. 
     As the piston advances, as shown in FIGS. 2 and 3, chamber 11 is blocked. The grapes are stored in funnel 3 which has a large capacity. 
     When rapid advance piston 9 reaches the end of its stroke, piston 10 and plate 6 are brought into action. Piston 10 and plate 6 are moved according to a cycle which comprises a slow and stepwise advance with slight retreat on each impulse to apply pressure to, or compress, the grapes and activate the flow of the juices. 
     Then the drained grapes are evacuated through door 5 by forming stopper 13. 
     Pistons 9 and 10 retract rapidly thus creating a vacuum in sector 12 of the pressure chamber. They allow, by opening of the feed chamber 11, the grapes to fall therein, while sector 14 of the stopper is evacuated. 
     The press is ready for a new cycle and returns to phase 1. 
     Door 5 remains open, the stopper 13 being able to furnish a sufficiently strong counterpressure to assure the extraction of the juices. However, one can modulate its closure to adjust the evacuation of the pressed grapes or to regulate the resistance force. 
     The pressure exerted by plates 6, 7 and telescopic shafts 10, 8 assure a complete and total extraction of the juices without grinding of the bunches, or stems, or of the seeds, or even tearing the ligneous portions. 
     The uniformly distributed pressure integrally, or completely drains the pulps; the compact and dry stopper, leaves at a rapid flow adapted to the feed sequences. 
     However, the configurations, dimensions and arrangements of the various elements may vary within the limit of equivalences as well as the materials utilized for their manufacture, without changing the general concept of the invention which has just been described.