Blown Film Bag Closure Device Deformation Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing closure devices with multiple complementary profiles face deformation issues during the extrusion-inflation process, leading to poor sealing and increased risk of opening due to stress at the interface between the profiles and the film, especially when produced by extrusion-inflation methods.
Innovation Solution
A manufacturing method involving an inflation rate less than 1.5, with complementary profiles formed integrally with their base via a connecting rod that maintains the base at a distance from the film, and sequential alterations to improve engagement and sealing, reducing deformation and stress between the profiles and the film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the inflation ratio is increased to improve film formation quality, then the film quality improves, but the deformation of closure devices increases due to differential necking
Solution Approach 1:
The closure device geometry is pre-corrected in the die design to anticipate and compensate for the deformation that will occur during inflation. By calculating the expected deformation based on the inflation ratio, the die is designed with adjusted dimensions so that after inflation, the closure device achieves the correct final geometry for proper profile engagement.
2Reliability
If multiple complementary profiles are used to improve sealing, then sealing performance improves, but stress concentration at the film interface increases leading to deformation
Solution Approach 1:
The closure device incorporates profiles with varying geometries and distributions tailored to specific locations. Certain profiles are designed with enhanced engagement features or modified shapes to distribute stresses more evenly across the film interface, preventing concentration of stresses that would lead to deformation while maintaining effective sealing at each profile location.
3Stability of the object's composition
If the inflation ratio is reduced to minimize deformation, then closure device shape stability improves, but film quality and thickness uniformity deteriorate
Solution Approach 1:
The die geometry is pre-corrected to account for the limited inflation expansion. By designing the die with adjusted dimensions that anticipate the smaller final size after low-ratio inflation, the closure device achieves correct geometric tolerances and shape stability without requiring high inflation ratios, thereby maintaining both shape stability and acceptable film quality.
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 method results in a more airtight closure device with improved sealing and reduced risk of accidental opening, maintaining stability and mechanical properties while allowing for tactile and sound effects, all at a moderate cost.
Implementation Method 1
In a second stage, the plastic material is heated and extruded in such a way as to plasticize it and form, through an annular die, a film of annular shape.
Implementation Method 2
In a third step, air is blown inside the film to inflate it and form a tube (or bubble).
Implementation Method 3
Air is also blown onto the tube from the outside through a system of rings to cool the extruded and inflated film.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a method for manufacturing (S) a bag (3) by means of blown film extrusion, including the following steps: extruding (S2) plastic such as to form an annular film (2) including closing assemblies (10, 20), said annular film being intended to form the walls of the bag; and blowing (S5) the annular film such as to form a sheath, the complementary profile sections (14, 24) of each of the closing assemblies (10, 20) being integrally formed with a base (18, 28) connected to the annular film (2) via a connection rod (19, 29) that extends parallel to the longitudinal axis (X) between the annular film (2) and the base (18, 28) and is designed to keep the base (18, 28) separated from the annular film (2).