Method for blow-molding a packaging container using a gas and device for implementing same
The invention relates to a method of gas blow forming packaging in a mould using a preform and comprising recovery of the blow gas. The inventive method comprises the following steps consisting in: —) pre-blowing the gas into the preform at a first pressure (P 1 ); —) blowing the gas into the pre-blown packaging at a second pressure (P 2 ) which is greater than the first pressure (P 1 ); —) blowing the gas into the partially-blown packaging at a third pressure (P 3 ) which is greater than the second pressure (P 2 ); —) recovering the gas in a recovery volume until a pre-determined pressure is obtained in the packaging or for a pre-determined period of time; —) using the recovered gas in order to preform pre-blowing operations and the first blowing step; and expanding the air that is free of residual gas in the packaging during and after the recovery phase. The invention also relates to a device that is used to implement said method.
1. A method for blow-molding a packaging container by means of a gas in a mold starting from a preform and for recovering the blow-molding gas according to the following steps:
pre-mold blowing of the gas under a first pressure (P 1 ) in a closed mold;
blow-mold blowing of the gas under a second pressure (P 2 ) higher than the first pressure (P 1 );
recovery of the gas in a recovery volume until a pre-determined pressure is reached in the container;
characterized by the following steps:
blow-mold blowing of the gas under a third pressure (P 3 ) higher than the second pressure (P 2 ) before the step for recovering the gas in a recovery volume until a pre-determined pressure is reached in the container or for a pre-determined time and use of the recovered gas at or below the predetermined recovery volume pressure for carrying out the pre-molding and the first blow-molding step operations;
release into the open air of the residual gas in the container during and after the recovery phase.
2. The method as claimed in claim 1 , wherein the first pressure value is between 4 and 16 bar, the second pressure value is around 18 bar and the third pressure value is between around 30 and 40 bar.
3. The method as claimed in claim 1 , wherein the pre-molding step lasts for between 0.1 s and 0.3 s.
4. The method as claimed in claim 1 , wherein the blow-molding step under the second pressure lasts for up to 0.3 s.
5. The method as claimed in claim 1 , wherein the blow-molding step under the third pressure lasts for between 0.2 s and 2 s.