Rotational moulding process and related mould for rotational moulding comprising a venting device

A rotational moulding process for producing an article, the process comprising:

• providing a mould comprising:
• a main body which defines an inner cavity having a conformation surface counter-shaped to said article, and
• a venting device fixed to said main body and comprising:
• an inner chamber in air communication with said inner cavity through a first mouth and with an outer environment through at least one second mouth and a third mouth;
• a shutter movable between an open position, in which said first mouth is open for putting said inner cavity in air communication with the outer environment, and a closed position, in which said first mouth is closed for preventing said air communication, said third mouth being arranged at an opposite side of said inner chamber with respect to said shutter;
• an actuator for alternately moving said shutter between the open position and the closed position,
• the process further comprising:
• inserting a fluid form polymeric material into said inner cavity;
• closing said main body and rotating said mould;
• while keeping the mould in rotation and with said shutter in the closed position, heating said main body until the main body reaches a first temperature;
• while keeping the mould in rotation, heating said main body until the main body reaches a second temperature higher than said first temperature;
• cooling said main body and extracting said article,
• during said heating said main body until the main body reaches the first temperature, subtracting heat from said shutter for maintaining said shutter at a respective temperature lower than said first temperature by generating an air flow that flows from the outer environment through the third mouth, touches a surface of said shutter facing away from said inner cavity and then returns to the outer environment through said at least one second mouth.