Method and packaging machine for producing sealed packages of pourable food products from precut blanks of sheet packaging material

1. A method of producing a sealed package of a pourable food product from a substantially tubular precut blank of sheet packaging material with opposite open ends, said method comprising:

feeding said blank onto a forming mandrel;

sealing one end of said blank on said mandrel to form a container open at the opposite end;

removing said container from said mandrel;

sterilizing said container before filling it with said pourable food product;

preheating said container before sterilizing it, wherein the preheating of said container is performed by heating said mandrel;

detecting a temperature of said mandrel; and

controlling the preheating of said container by controlling the heating of said mandrel based on the detected temperature.

2. A packaging machine for producing sealed packages of pourable food products from substantially tubular precut blanks of sheet packaging material with opposite open ends, said machine comprising:

a sealing station for sealing one end of said blanks to form respective containers open at the opposite end, and

a sterilizing station for sterilizing said containers, said sealing station comprising a plurality of forming mandrels engaging respective blanks and traveling along a given path, along which each blank is converted into a container open at one end;

wherein said sealing station comprises heating means for heating said mandrels to transmit heat to the containers before they are fed to said sterilizing station and means for controlling the temperature of each mandrel.

3. A machine as claimed in claim 2 , wherein said heating means comprise an electric resistance heater for each mandrel.

4. A machine as claimed in claim 2 , further comprising:

a plurality of temperature sensors for detecting respective temperatures of the plurality of mandrels, wherein the controlling means controls each heating means based on the detected temperature to control the heating of each mandrel.

5. A machine as claimed in claim 2 , further comprising:

a sensor mounted on the mandrel for providing information relating to the temperature of the mandrel, wherein said means for controlling is operatively connected to the sensor to control the temperature of the mandrel based on information provided by the sensor.

6. A method of producing a sealed package of a pourable food product from a substantially tubular precut blank of sheet packaging material with opposite open ends, said method comprising:

feeding said blank onto a forming mandrel;

sealing one end of said blank on said mandrel to form a container open at the opposite end;

preheating said container by heating said mandrel to increase a temperature of an inner surface of the container;

removing said container from said mandrel; and

sterilizing said container with hydrogen peroxide vapor at a sterilizing station, before filling the container with the pourable food product, the preheating of the container comprising preheating the container so that the temperature of the inner surface of the container at the sterilizing station is higher than a condensation temperature of the hydrogen peroxide vapor.

7. A packaging machine for producing sealed packages of pourable food products from substantially tubular precut blanks of sheet packaging material with opposite open ends, said machine comprising:

a sealing station for sealing one end of said blanks to form respective containers open at the opposite end, and

a sterilizing station downstream of the sealing station for sterilizing said containers with a vapor sterilizing agent, said sealing station comprising a plurality of forming mandrels engaging respective blanks and traveling along a given path, along which each blank is converted into a container open at one end;

wherein said sealing station comprises heating means for heating said mandrels to transmit heat to an inner surface of each container so that the temperature of the inner surface of the container at the sterilizing station is higher than a condensation temperature of the vapor sterilizing agent.

8. A packaging machine as claimed in claim 7 , further comprising a sensor mounted on one of the mandrels to provide information relating to the temperature of the one mandrel.