METHOD AND APPARATUS FOR BLOW MOULDING OF CONTAINERS WITH A MOVABLE BASE PART

• US 20190315039A1
• Filed: 12/11/2017
• Published: 10/17/2019
• Est. Priority Date: 12/23/2016
• Status: Active Grant

• Current Assignee: Krones AG (Krones)
• Original Assignee: Krones AG (Krones)
• Inventors: Huettner, Gerald, Laine, Ludovic
• Granted Patent: US 11,554,527 B2
• Time in Patent Office: Days
• CPC Class Codes: B29C 2049/023 using inherent heat of the preform, i.e. 1 step blow moulding
• CPC Class Codes: B29C 2049/4892 Mould halves consisting of an independent main and bottom part
• CPC Class Codes: B29C 2049/7833 Blowing with three or more pressure levels
• CPC Class Codes: B29C 2949/0715 the preform having one end closed
• CPC Class Codes: B29C 49/06 Injection blow-moulding
• CPC Class Codes: B29C 49/12 Stretching rods
• CPC Class Codes: B29C 49/36 rotatable about one axis
• CPC Class Codes: B29C 49/48 Moulds
• CPC Class Codes: B29C 49/78 Measuring, controlling or regulating
• CPC Class Codes: B29L 2031/7158 Bottles

Abstract

A method for forming plastic parisons to plastic bottles includes the following steps: introducing in a blow mold a plastic parison to be expanded, the blow mold having at least two lateral parts and a base part that is mobile in relation to said lateral parts in a longitudinal direction of the plastic parison; inserting a rod-shaped element in the interior of the plastic parison through a mouth of the plastic parison; applying a first pressure the plastic parison, applying a second pressure to the plastic parison, the second pressure deviating from the first pressure and being higher than the first pressure, applying a third pressure to the plastic parison, the third pressure deviating from the second pressure and being higher than the second pressure. The base part is advanced in the longitudinal direction of the plastic parison while at least temporarily applying the second pressure to the plastic parison.

Claims

1. Method for transforming plastic parisons into plastic bottles, comprising the following steps:

introducing a plastic parison which is to be expanded into a blow mould, wherein this blow mould has at least two lateral parts and a base part which is movable relative to these lateral parts in a longitudinal direction of the plastic parison,

inserting a rod-shaped body into the interior of the plastic parison through a mouth of the plastic parison,

applying a first pressure to the plastic parison,

applying a second pressure to the plastic parison, wherein this second pressure deviates from the first pressure and is preferably higher than the first pressure,

applying a third pressure to the plastic parison, wherein this third pressure deviates from the second pressure and is preferably higher than the second pressure,

wherein at least temporarily while the second pressure is applied to the plastic parison, the base part is advanced towards the plastic parison in the longitudinal direction of the plastic parison.

2. Method according to claim 1, wherein the rod-like body is at least partially retracted before or during the advancement of the base part.

3. Method according to claim 1, wherein the base part is advanced by a distance which is greater than 5 mm, preferably greater than 10 mm and particularly preferably greater than 15 mm and/or that the base part is advanced by a distance which is less than 30 mm, preferably less than 25 mm and particularly preferably less than 20 mm.

4. Method according to claim 1, wherein after the application of the third pressure the plastic parison is again relieved of pressure.

5. Method according to claim 1, wherein after the application of the third pressure to the plastic parison the base part is retracted again.

6. Method according to claim 1, wherein the base part is advanced at least temporarily while the first pressure is applied to the plastic parison.

7. Method according to claim 1, wherein the base part is advanced for a duration which is between 1 sec and 20 sec, preferably between 1 sec and 15 sec and preferably between 2 sec and 10 sec and particularly preferably between 2 sec and 5 sec.

8. Method according to claim 1, wherein for the duration of the application of the third pressure to the plastic parison the base part always remains advanced towards the plastic parison.

9. Method according to claim 1, wherein the second pressure is greater than 3.5 bar, preferably greater than 5 bar, preferably greater than 7 bar and particularly preferably greater than 10 bar and preferably greater than 12 bar and/or the second pressure is less than 20 bar, preferably less than 18 bar, and particularly preferably less than 17 bar.

10. Apparatus for transforming plastic parisons into plastic bottles with at least one transport device on which a plurality of transforming stations are arranged, wherein each of these transforming stations has blow moulds which in each case have two lateral parts, which are movable with respect to one another for opening and dosing the blow mould, as well as a base part, wherein this base part is movable relative to the lateral parts in a longitudinal direction of the plastic parison and in a closed state of the blow mould, and wherein the apparatus furthermore has at least one application device in order to apply a gaseous medium and in particular compressed air to the plastic parisons for expansion thereof, as well as a control device which controls the application of the gaseous medium to the plastic parisons in such a way that first of all a first pressure, then a second pressure which is above the first pressure, and finally a third pressure preferably above the second pressure, are applied to the plastic parisons, characterised in that the apparatus has a driving device which is suitable and intended to move the base part at least temporarily during the application of pressure to the plastic containers, wherein at least temporarily while the second pressure is applied to the plastic parison, the base part is moved towards the plastic parison in the longitudinal direction of the plastic parison.