Blow molding machine and method

A blow pin assembly for blowing aseptic plastic bottles, the assembly including:

• A) an elongate blow pin having a blow end, a sterile blow passage located in the blow pin and extending along the pin to a blow mouth at the blow end of the pin, and an exhaust passage located in the blow pin and extending along the blow pin to an exhaust mouth at the blow end of the blow pin, the exhaust mouth located adjacent to the blow mouth, the exterior surface of said pin being sterile from the blow end a distance along the pin away from the blow end;
• B) a blow pin sterilization maintenance device surrounding the blow pin to maintain the sterility of the surface of the blow pin;
• C) a blow pin drive for axially extending and retracting the blow pin to move the blow pin between a retracted position with the sterile surface of the pin located adjacent the sterilization maintenance device and an extended blow position with the end of the blow pin located away from the sterilization maintenance device for engagement with a parison held in a blow mold cavity;
• D) a first source of sterile blow gas connected to the blow passage of the blow pin away from the blow end;
• and
• E) a vacuum source connected to the exhaust passage of the blow pin away from the blow end;
• F) wherein when the blow pin is retracted the blow pin sterilization maintenance device maintains surface sterility of the pin and when the blow pin is extended into a parison held in a mold cavity sterile blow gas flowed into the parison from the source of sterile blow gas and through the blow passage blows the parison to form a sterile bottle and blow gas is exhausted from the bottle to the vacuum source through the exhaust passage without exhausting blow air through the blow passage to maintain sterility of the blow passage.

The method of blowing a sealed aseptic plastic bottle using a blow molding machine having a blow pin with a blow end, a sterile internal blow passage extending from a source of sterile blow gas through the blow pin to the end of the pin, a blow pin housing surrounding the blow pin and a blow pin drive to move the blow pin between extended and retracted positions, including the steps of:

• A) moving the blow pin to the retracted position to locate an end portion of the pin in the housing, flowing sterile gas at low pressure into a chamber between the pin and housing so that the sterile gas surrounds the pin and flows axially along the pin in laminar flow and over the end of the pin and the end of the blow passage to maintain sterility of the end of the pin and the passage;
• B) locating a closed blow mold with a parison captured in a blow cavity adjacent the blow pin;
• C) moving the blow pin outwardly from the housing to an extended position to locate the end of the blow pin in the mold in contact with the parison and with the end of the blow passage communicating with the interior of the parison while continuing to flow sterile air outwardly from the housing and along the blow pin to maintain sterility of the extended blow pin;
• D) maintaining the blow pin in contact with the parison while
• i) blowing sterile gas through the sterile blow passage, out the end of the passage and into the parison to blow the parison and form a sterile bottle;
• ii) removing blow gas from the interior of the blown bottle while maintaining the sterility of the blow passage to reduce the pressure within the bottle;
• and
• iii) sealing the bottle closed at a location below the blow pin after blow gas has been removed from the bottle;
• E) separating the blow pin from the bottle, moving the blow pin back to the retracted position in the housing and continuing to flow low pressure sterile gas along the pin in laminar flow and around the end of the pin to maintain the sterility of the pin;
• and
• F) opening the mold and removing the blown bottle.

A blow pin assembly for use in blow molding aseptic plastic bottles, the assembly including:

• A) an elongate blow pin having a blow end, the pin including a sterile internal blow air passage extending along the pin and having a blow mouth at the blow end of the pin;
• B) an annular blow pin housing surrounding the blow pin, the housing defining an upper opening and a lower mouth, and a sterile gas inlet port opening into a first annular chamber between the housing and the blow pin;
• C) a first circumferential seal adjacent the upper opening, said first seal extending between the housing and the blow pin whenthe blow pin is in a retracted position and the blow end of the pin is adjacent the housing, the surface of the pin below the first seal being sterile;
• and
• D) a drive for moving the blow pin between the retracted position and an extended position where the blow end of the pin is extended outwardly below the housing in position to blow a parison held in a closed mold below the housing,
• E) wherein when the blow pin is in the retracted position sterile gas flowed into the chamber through the sterile gas inlet port surrounds the blow pin, flows along the blow pin in laminar flow and across the blow end of the pin to shield the sterile pin from contamination by atmospheric air.