Plastic Container Compression Preventing Stress Whitening
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Solution Overview
Problem
The existing methods for compressing plastic containers often result in white fractures and instabilities, making it difficult to remove the containers from the holding device and affecting their stackability due to uncontrolled folding and pressure issues during the compression process.
Innovation Solution
A device with a first holding device that has a smaller cross-section than the container, allowing it to roll into the container and form a controlled circumferential fold, combined with a pressure-generating device to apply internal pressure above external pressure, and a stop element to manage the fold, preventing kinking and stress whitening, along with temperature control to maintain the fold position after decompression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the container is compressed by rolling the mouth area into the bottom area, then the compression is controlled and systematic, but white fractures and stress whitening occur leading to container instability
Solution Approach 1:
The patent applies internal pressure to the container during compression to prevent stress whitening and material failure. By controlling the pressure parameter within a specific range (0.5-5 bar), the material maintains its integrity while being deformed, thus resolving the contradiction between controlled compression and container stability
Solution Approach 2:
The patent introduces a stop element as an intermediary component that contacts the fold at a predetermined position. This stop element mediates the compression process by preventing excessive folding and controlling the deformation, thereby preventing white fractures while maintaining systematic compression
2Stress or pressure
If the container is compressed and then depressurized, then the internal pressure is reduced to atmospheric pressure, but the folds contract and become creased making removal difficult
Solution Approach 1:
The patent applies internal pressure during the compression process as a preliminary action to prevent fold contraction and creasing. By maintaining pressure while the fold is being formed and positioned, the material remains pliable and the fold stays in the desired configuration, preventing the tightening that would occur upon depressurization
Solution Approach 2:
The patent controls the pressure parameter throughout the compression and holding process. By maintaining appropriate internal pressure during fold formation and only reducing it after the fold is stabilized by the stop element, the material properties are optimized to prevent creasing and facilitate easy removal
3Stability of the object's composition
If the fold tightens strongly on the stamp after venting, then the compressed container can only be detached with difficulty, but maintaining pressure prevents proper folding
Solution Approach 1:
The stop element serves as an intermediary that takes over the function of holding the fold in position. Once the fold reaches the predetermined position and contacts the stop element, the stop element maintains the fold position without requiring continuous pressure, thus preventing tight tightening on the stamp while ensuring fold stability
Solution Approach 2:
The stop element is positioned in advance at the predetermined location where the fold should stop. This preliminary positioning ensures that when the fold reaches this point during compression, it is automatically stabilized without excessive tightening, facilitating easy detachment while maintaining fold integrity
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
The solution facilitates easier removal of compressed containers from the holding device and improves stackability by preventing kinking and stress whitening, ensuring the containers maintain pressure stability and barrier properties.
Implementation Method 1
a pressure-generating device (26) is provided, which applies an internal pressure to an interior of the container to be compressed at least temporarily during its compression, with an internal pressure that exceeds the external pressure around the container
Implementation Method 2
a stop element (22) is provided on the first holding device, which contacts the folding point in a predetermined relative position of the first holding device with respect to the second holding device
Implementation Method 3
the first holding device (2) has a temperature control device (24) for the temperature control of at least one section of the first holding device
Data Source
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AI summary
An apparatus (1) for compressing plastic containers (10), having a first retaining device (2), which is suitable for retaining a first region (10a) of a container (10) which is to be emptied, having a second retaining device (4), which is suitable for retaining and/or for supporting a second region (10b) of the container (10) which is to be emptied, the second region (10b) being spaced apart from the first region (10a), and having a movement device (17, 19), which is suitable for moving the first retaining device (2) in the direction of the second retaining device (4), in order to compress the container (10) located between the first retaining device (2) and the second retaining device (4), wherein the first retaining device (2) has a cross section which is preferably smaller than a cross section of the container which is to be compressed, and therefore it is possible for the first retaining device to be introduced, with the first region (10a) of the container retained by the first retaining device (2), into a further portion of the container (10) to form an encircling folding location (10c), as seen in a longitudinal direction (Y) of the container (10). According to the invention, the first retaining device (2) has provided in it a stop element (22), which makes contact with the folding location (10c) at a predetermined position of the first retaining device (2) relative to the second retaining device (4), and/or the apparatus (1) has a pressure-generating device (82), by means of which an interior of the container which is to be compressed is subjected, at least at certain times during the compressing operation, to an internal pressure which is above the external pressure in the area around the container (10).