Method and machine for manufacturing containers allowing a modification of heating rate

1. A method of manufacturing containers from blanks of plastic material on a production line comprising a critical machine having a proper tempo, the method comprises:

a phase of heating blanks as they pass through an oven provided with a plurality of radiation sources, at a predetermined speed of travel (V) and heating profile;

a phase of blowing the blanks in a blowing unit, in order to form the containers, said method comprising:

(a) modifying the speed (V) of movement of the blanks in accordance with the tempo of the critical machine, wherein the modification is incremental and corresponds only to a percentage of a final modification sought;

(b) modifying the heating profile with regard to the modified speed;

(c) establishing, at the end of a heating phase, an actual thermal profile of at least one blank;

(d) measuring a pressure in said blank during the blowing phase and detecting at least one singular pressure point (B);

(e) measuring a first difference between the actual thermal profile of the blank and a theoretical thermal profile, and a second difference between the singular pressure point and a theoretical singular pressure point;

(f) as long as the differences are not both below a respective predetermined tolerance, repeat operations b) to e);

(g) as long as the differences are both below the respective tolerance, and while the speed of travel (V) has not reached a predetermined final value, repeat operations a) to e).

2. The method according to claim 1 , characterized in that the actual thermal profile comprises a thermography of the blank.

3. The method according to claim 1 , characterized in that the actual thermal profile comprises a temperature measurement made on an outer wall of the blank.

4. The method according to claim 1 , characterized in that the actual thermal profile comprises a temperature measurement made on an inner wall of the blank.

5. The method according to claim 1 , characterized in that the singular pressure point is a local pressure peak.

6. The method according to claim 1 , characterized in that the heating profile comprises an electric power (P S ) delivered to the radiation sources.

7. The method according to claim 1 , characterized in that the heating profile comprises an electric power (P V ) delivered to a ventilation system of the oven.

8. A method of manufacturing containers from blanks of plastic material on a production line comprising a critical machine for processing a container following a blow molding of the blanks in a blowing unit, the critical machine having a certain tempo, the method comprises:

a phase of heating blanks as the blanks pass through an oven provided with a plurality of radiation sources at a predetermined speed of travel and heating profile;

a phase of blowing the blanks in the blowing unit, in order to form the containers, wherein the phase of blowing comprises:

(a) modifying the speed of travel of the blanks in accordance with the tempo of the critical machine, wherein the modification is incremental and corresponds only to a percentage of the final modification sought;

(b) modifying the heating profile based on the modified speed of travel;

(c) establishing, at the end of a phase of heating, an actual thermal profile of at least one blank;

(d) measuring a pressure in the blank during the phase of blowing phase and detecting a pressure point from the measured pressure;

(e) measuring a first difference between the actual thermal profile of the blank and a theoretical thermal profile, and a second difference between the pressure point and a theoretical pressure point;

(f) as long as the differences are not both below a respective predetermined tolerance, repeat operations b) to e);

(g) as long as the differences are both below the respective tolerance, repeat operations a) to e) until the speed of travel has reached a predetermined final value.