Optimized Design of a Grape Marc Press with helicoidal Screw

A grape mashing machine has been set up to use during the mashing process, that is able to operate in continuous way and to act with a pressure distribution in according to the oenological requirements. Besides the methodology used, it has allowed to design mashing machines with conic helicoidal screws that realize any preset pressure distribution required during the mashing process. The mashing work is performed by mean a device with conical screws with changing pitch, that cause on the elementary control volumes, with which they interact, a pressure increasing Dp that depended by the helicoidal surfaces geometry and by how it changed along the machine axis. Insofar it has been necessary to study of the conical helicoidal surfaces that interact with the control volume of the considered product, as well as, how these change along the machine axis. In such way it has been possible to determine both the pressure at which the control volume is submitted and the pressure gradient that is obtained along the machine axis. Insofar conical helicoidal screws with changing pitch have been examined and the elementary control volume that is ranged between the considered helicoidal surface, it has been studied, and following a “Lagrangian” procedure type, its characteristic has been studied during the rotatory - translatory motion that happened along the machine axis, determining the conical helicoidal geometry to use to mash the considered grapes according to the pressure distribution assigned during the operative phase.