Inner Bag Detachment in Co-Extruded Containers
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Solution Overview
Problem
Existing methods for detaching the inner bag from the outer container wall in coextruded containers are complex, time-consuming, and often result in incomplete detachment, especially in the shoulder area, leading to impaired functionality and reduced production efficiency.
Innovation Solution
The method involves cutting diametrically opposite holes in the outer container's shoulder section and using pins to mechanically lift the inner bag, followed by applying external pressure or negative pressure through these holes to ensure complete detachment in a single cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods (pins through holes, pressure medium) are used to detach the inner bag, then the inner bag can be pushed away from the container wall, but the process is complex, time-consuming, and requires considerable external overpressure
Solution Approach 1:
The detachment process is divided into two distinct stages: first, partial detachment is achieved by inserting pins through pre-cut holes in the outer container wall to lift the inner bag locally; second, complete detachment is achieved by applying pressure medium through the same holes. This segmentation allows each stage to serve a specific function, reducing overall complexity while ensuring reliable detachment.
Solution Approach 2:
Holes are cut into the outer container wall at the lower edge of the shoulder section before the detachment process begins. These pre-cut holes serve as access points for both the pins and the pressure medium, eliminating the need for complex drilling operations during the detachment phase and simplifying the overall process.
2Reliability
If conventional methods are used to detach the inner bag, then detachment can be achieved, but production time increases
Solution Approach 1:
The detachment process is divided into two distinct stages: first, partial detachment is achieved by inserting pins through pre-cut holes in the outer container wall to lift the inner bag locally; second, complete detachment is achieved by applying pressure medium through the same holes. This segmentation allows each stage to serve a specific function, reducing overall complexity while ensuring reliable detachment.
Solution Approach 2:
Holes are cut into the outer container wall at the lower edge of the shoulder section before the detachment process begins. These pre-cut holes serve as access points for both the pins and the pressure medium, eliminating the need for complex drilling operations during the detachment phase and simplifying the overall process.
3Reliability
If conventional methods are used to detach the inner bag, then detachment can be achieved, but considerable external overpressure is required
Solution Approach 1:
The detachment process is divided into two distinct stages: first, partial detachment is achieved by inserting pins through pre-cut holes in the outer container wall to lift the inner bag locally; second, complete detachment is achieved by applying pressure medium through the same holes. This segmentation allows each stage to serve a specific function, reducing overall complexity while ensuring reliable detachment.
Solution Approach 2:
A pressure medium (gas or liquid) is introduced as an intermediary substance to transfer force from the external environment to the inner bag. This intermediary allows for controlled, gradual detachment without requiring direct mechanical force or considerable external overpressure, as the pressure medium can be regulated to achieve the desired detachment effect.
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 allows for reliable and faster detachment of the inner bag over the entire surface, reducing production time and minimizing the risk of damage, while requiring less pressure compared to conventional methods.
Implementation Method 1
the preform is inflated by a pressure medium to rest against the wall of the blow mold
Implementation Method 2
pins are inserted through the holes, preferably vertically, between the inner bag and the outer container to detach the inner bag from the inner wall of the outer container
Implementation Method 3
external positive pressure to be exerted through the holes on the inner bag and/or negative pressure to be generated within the inner bag in order to detach the inner bag from the inner wall of the outer container
Data Source
Figure 1A~2B
AI summary
The method for producing a usable container consisting of a rigid outer container (1) and a deformable inner bag, wherein a first screw conveyor feeds a first thermoplastic material for the outer container (1) and at least a second screw conveyor feeds at least a second thermoplastic material for the inner bag to an extruder which co-extrudes a preform which is arranged between the open halves of a blow mold of a blow molding machine, wherein the blow mold is closed when the preform has the length required to produce the container, wherein excess material in the bottom region of the container to be produced is squeezed off and a web of material from the outer container is formed in which the welded bottom seam of the inner bag is clamped, and wherein the preform is inflated by a pressure medium to conform to the wall of the blow mold,The process, in which the excess material is knocked off below the weld seam and the container is removed from the blow mold, is characterized by the following steps: a) At least two preferably diametrically opposed holes (3) are cut into the outer container (1) at the lower edge region of the shoulder section (2); b) Pins are inserted through the holes (3), preferably vertically, between the inner bag and the outer container (1) to detach the inner bag from the inner wall of the outer container; c) An overpressure is exerted on the inner bag from the outside through the holes (3) and/or a vacuum is created in the inner bag to detach the inner bag from the inner wall of the outer container.