Rolling mill with direct drive motors and method for operating said rolling mill

A rolling mill for grinding and processing cereals, granular materials, and mixtures of cereals, said rolling mill comprising:

• a pair of parallel cylinders comprising a first cylinder and a second cylinder positioned side by side, wherein the first cylinder and the second cylinder are provided with a respective torque motor, the torque motor being mounted on a shaft of the respective cylinder or being built directly on the shaft of the respective cylinder;
• and
• a control circuit to which a respective set of coils or windings of the motor of the first cylinder and of the motor of the second cylinder, respectively, is connected, the control circuit being capable to supervise rotation parameters of said first and second cylinders;
• wherein said first and second cylinders have a grooved surface, comprising a plurality of projections with cross section in a shape of saw teeth, an asymmetrical triangular cross section, each projection defining a cutting edge, or blade, and an inclined surface, or back;
• wherein the control circuit controls a power supply and change of polarity or power intensity of said coils or windings of the motors in an independent manner through respective control units and wherein the control circuit selects which one of the first and second cylinders rotates faster, thus defining a faster cylinder and a slower cylinder for the pair of parallel cylinders, and thus further defining a faster torque motor and a slower torque motor, respectively,
• wherein said faster cylinder can selectively be the first cylinder or the second cylinder according to a processing of cereals, granular materials, mixtures of cereals to be obtained, whereby by making the first cylinder rotate faster it is possible to obtain a processing of cereals, granular materials, mixtures of cereals that is different from a the processing cereals, granular materials, mixtures of cereals obtained by making the second cylinder rotate faster;
• wherein the control circuit controls the power supply and the change of polarity of the coils or windings of the motors of the first and second cylinders by transmitting a higher rotation speed and torque for one of the two cylinders, while in the other cylinder, which is the slower cylinder, the respective motor operates as a brake, wherein the control units comprise a control unit of the slower motor and a control unit of the faster motor, and wherein the control unit of the slower motor recovers energy not used by the slower cylinder, making the energy recovered by the control unit of the slower motor available to the faster motor and transmitting the recovered energy directly to the respective control unit of the faster motor;
• wherein the control units control operating parameters comprising torque of each motor, number of revolutions of the cylinders, power absorption, temperature and speed ratio between the cylinders, said control circuit comprises a plurality of predefined programs comprising one or more sequences of said operating parameters, wherein said programs are selectable according to the type of cereals to be grinded.