Plastic Spout With Gradient Wall Thickness for Uniform Film Bag Sealing
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Solution Overview
Problem
The introduction of a spout into film bags for liquid consumer goods poses difficulties in achieving a uniform and reliable seal due to varying surface rigidities and pressures between the sealing tool, film edges, and side walls, especially with thin wall thicknesses, leading to irregularities and errors in sealing or welding processes.
Innovation Solution
The spout design features uneven wall thickness with increased thickness towards the open edges and slightly diverging sealing surfaces, providing a uniform stiffening and compensation for deformation, allowing for even pressure distribution during sealing, and is made from injection-moldable plastic materials like polyethylene.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the spout is designed with thin wall thicknesses (about 1.0 mm or less) to save material and reduce weight, then material consumption and weight are reduced, but the sealing uniformity and reliability deteriorate due to varying surface rigidities and pressure distribution
Solution Approach 1:
The spout is designed with non-uniform wall thickness where the wall thickness increases from the bottom toward the open end. This local variation in thickness creates corresponding variation in rigidity along the sealing surface, with thicker walls at the open end providing greater rigidity to compensate for the naturally lower pressure in that region during sealing, while thinner walls at the bottom reduce overall material consumption.
2Productivity
If the spout is designed with thin wall thicknesses to enable fast injection molding and adapt to flexible film bags, then production speed and adaptability are improved, but sealing uniformity deteriorates due to insufficient structural support and pressure distribution
Solution Approach 1:
The gradient wall thickness design allows thin walls (0.3-1.0 mm) in the bottom region for fast cooling and molding, while progressively increasing thickness toward the open end (up to 1.5-2.0 mm) to provide sufficient rigidity and uniform pressure distribution during sealing, thus achieving both fast production and high sealing precision.
Solution Approach 2:
The wall thickness parameter is varied continuously or in steps along the height of the spout, creating a gradient structure that optimizes the balance between molding speed (requiring thin walls) and sealing quality (requiring adequate rigidity), allowing the spout to adapt to flexible film bags while maintaining sealing uniformity.
3Device complexity
If the sealing surfaces are made flat and uniform to simplify the design, then manufacturing complexity is reduced, but pressure distribution during sealing becomes uneven due to differential stiffening from curvature and internal supports
Solution Approach 1:
Instead of making the entire sealing surface complex to achieve uniform pressure, the design keeps the overall structure simple with a gradient wall thickness. The varying thickness itself creates the desired variation in local rigidity, with thicker sections providing natural stiffening where needed, eliminating the need for additional curvature or internal reinforcement elements.
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 design ensures a more reliable and uniform seal or weld between the spout and film edges, reducing material stress and deformation, and facilitating easier demolding, while maintaining a smooth, rib-free sealing surface.
Implementation Method 1
The increase in wall thickness towards the open edges is also suitable for counteracting the deformation of the socket as a result of high material shrinkage of the plastic material after injection molding
Implementation Method 2
The increase in wall thickness towards the open edges is also suitable for counteracting the deformation of the socket as a result of high material shrinkage of the plastic material after injection molding
Data Source
Figure 1~2
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Figure 5~6
AI summary
A plastic spout (1) for foil bags with a nozzle (2) and a lanceolate spout (3) with two side walls (9, 10) and external sealing surfaces (22, 23) which converge to form two opposite end areas (11, 12), are connected at the edges (18, 19) facing the nozzle (2) and are open at the opposite edges (20, 21), is designed to ensure even pressure between the sealing tool, foil edges and side walls by having a non-uniform wall thickness that increases towards the open edges (20, 21).