Hot-Filled Container Bottom Shaping via Fluid Jet
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Solution Overview
Problem
Hot-filled plastic containers deform inwardly due to negative pressure during cooling, and existing methods for compensating this deformation are either design-unfriendly or require complex equipment and late-stage activation, leading to transportation issues and potential permanent deformation.
Innovation Solution
The method involves using a fluid jet or fluid pressure wave to shape the bottom of hot-filled containers from a bulged outward state to an inward state, allowing for early activation without mechanical elements, and can be applied in various orientations during or after filling and closing, particularly using jets of water or compressed air in the neck sterilization or recooling stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If vacuum compensation surfaces (panels) are integrated into the side wall of containers to compensate for negative pressure during cooling, then the deformation of containers is controlled, but the design freedom is reduced and labeling on side walls is impeded
Solution Approach 1:
The invention extracts the vacuum compensation function from the side wall panels and relocates it to the bottom of the container. By creating a recess in the bottom that is drawn inward during cooling, the compensation function is separated from the side wall surface, thereby maintaining design freedom and labeling capability on the side walls while still controlling container deformation.
Solution Approach 2:
The invention transitions the vacuum compensation mechanism from a two-dimensional panel on the side wall to a three-dimensional recess structure in the bottom of the container. This dimensional change allows the compensation function to be integrated into the container's volumetric structure rather than occupying surface area, preserving side wall availability for design and labeling.
2Manufacturing precision
If the bottom of panel less bottles is mechanically forced inwardly with a punch while clamped between turntable and centering bell, then the bottom shaping is achieved, but the equipment complexity increases due to complicated lifting mechanism and the activation occurs at late stage after containers have largely cooled down
Solution Approach 1:
The invention replaces the complex mechanical punch and lifting mechanism with a mold cavity approach. The recess in the bottom is formed directly by the mold cavity during the blow molding process, eliminating the need for separate mechanical shaping equipment and complex lifting mechanisms while achieving precise bottom shaping.
Solution Approach 2:
The bottom recess is formed during the initial blow molding process rather than as a separate subsequent operation. By incorporating the recess formation into the primary manufacturing step, the bottom is shaped before the container is filled and cooled, eliminating the need for late-stage activation equipment and mechanisms.
3Manufacturing precision
If the bottom of panel less bottles is mechanically forced inwardly with a punch, then the bottom shaping is achieved, but the containers may have already deformed in an undesirable manner by the time shaping occurs after they have largely cooled down
Solution Approach 1:
The bottom recess is formed during the initial blow molding process while the plastic material is still hot and formable. This preliminary formation of the recess structure prevents subsequent deformation during filling and cooling operations, as the compensating geometry is already in place before the container undergoes thermal contraction and pressure changes.
4Ease of manufacture
If containers are handled in the non-activated state of the bottom until the bottom has been shaped, then the bottom shaping can be performed, but reliable transport of containers standing upright becomes more difficult and requires appropriately adapted transport devices
Solution Approach 1:
The bottom recess is formed during the blow molding process, creating the activated bottom structure before the container leaves the molding machine. This ensures that containers are transported in their final, stable configuration from the outset, eliminating handling issues associated with unactivated bottoms and requiring no special transport adaptations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces the volume of containers by at least 50% to counteract negative pressure, preventing unwanted deformation and allowing for reliable transportation and storage with minimal equipment complexity, while enabling flexible design and labeling options for thin-walled plastic bottles.
Implementation Method 1
the bottoms are forced inwardly by at least one fluid jet and/or one fluid pressure wave
Implementation Method 2
The bottoms are preferably forced inwardly by a jet of water, in particular a jet of cooling water
Implementation Method 3
The bottoms are preferably forced inwardly by a jet of cooling water. As a result, the bottoms can be forced inwardly in a production step immediately downstream of where the containers are closed, in particular during neck sterilization, or, for example, when the containers are recooled. A desired cooling effect and the activation of the container bottom can be effected simultaneously, in particular, with a jet of cooling water
Data Source
AI summary
A method is described for shaping the bottom of hot-filled containers, in which the bottoms of the containers are forced inwardly from a state bulged outwardly, in particular as they cool down. Complex mechanisms for forcing the bottom inwardly are dispensable for the reason that the bottoms are forced inwardly by at least one fluid jet and/or fluid pressure wave. In addition, shaping the bottom can advantageously be carried out in a production region immediately downstream of a closer.