Longitudinal Sealing Device Offset Roller Configuration
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Solution Overview
Problem
Existing longitudinal sealing devices for packaging materials, particularly those using monofilms or thin heat-sealing films, face issues with stability and weld quality due to the application of heat, leading to tensile forces and warping, which compromise the integrity of the seal, especially at higher film speeds.
Innovation Solution
A longitudinal sealing device is designed with a configuration where the transport rollers engage non-heated areas of the packaging material, ensuring stability and preventing the transport rollers from negatively affecting the sealed seam, by positioning the sealing and transport rollers such that the transport rollers act on unheated sections, thereby maintaining the integrity of the seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a heated roller pair is used to seal the packaging material, then the sealing quality is improved, but the material stability deteriorates due to tensile forces and warping
Solution Approach 1:
The sealing process is divided into two independent stages: a first heated roller pair creates the initial seal, and a second heated roller pair completes the sealing process. This segmentation allows the material to be stabilized between stages, preventing warping while maintaining sealing quality.
Solution Approach 2:
A cooling device is introduced as an intermediary element between the two heated roller pairs. This cooling device temporarily stabilizes the packaging material by reducing heat-induced warping and tensile forces, allowing the sealing process to continue without compromising material stability.
2Ease of operation
If the transport roller pair is positioned at the same level as the heated roller pair, then the hose transport is simplified, but the seal integrity deteriorates due to negative effects on the melted film section
Solution Approach 1:
The transport roller pair is positioned in a different vertical dimension (height level) relative to the heated roller pairs. Specifically, the transport rollers are arranged above the heated rollers, allowing them to engage the packaging material at a location that does not interfere with the sealing process, thus maintaining seal integrity while preserving transport functionality.
3Productivity
If higher film speeds are used to increase productivity, then the production efficiency is improved, but the weld quality deteriorates due to increased tensile forces and distortion
Solution Approach 1:
The first heated roller pair performs preliminary sealing action before the material enters the cooling device. This preliminary action creates an initial bond that stabilizes the material, allowing it to withstand higher speeds without compromising final weld quality when completed by the second roller pair.
Solution Approach 2:
The system changes the thermal parameters dynamically by using two separate heated roller pairs with potentially different temperature settings, combined with intermediate cooling. This parameter control allows the material to be processed at higher speeds while maintaining weld quality through controlled heating and cooling cycles.
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 configuration enhances the quality of the longitudinal seal by preventing the introduction of tensile forces and warping, allowing for high-quality sealing even with temperature-sensitive films and at higher film speeds, while ensuring the seal remains unaffected by the transport process.
Implementation Method 1
a heated pair of sealing rollers (9) for providing the longitudinal seal (2) between the two layers (6, 7)
Implementation Method 2
The tube section (4) is moved on a first side, preferably above, and the seam section (5) on a second side, preferably below, a transport plane (T) of the longitudinal sealing device along a direction of travel (L) parallel to this transport plane
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
The invention relates to a longitudinal sealing device (1) for producing a sealed longitudinal seam (2) on a packaging material (3) which has a tubular portion (4) and a seam portion (5) that adjoins the tubular portion (4) and comprises the sealed longitudinal seam (2). A first layer (6) of the packaging material and a second layer (7) of the packaging material lie one above the other in the seam portion (5). The tubular portion (4) lies above a transport plane (T) of the longitudinal sealing device (1), and the seam portion (5), lying below the transport plane, is moved along a running direction (L) parallel to the transport plane (T). The longitudinal sealing device (1) comprises a positioning device (8) in order to position the two layers (6, 7) relative to each other, a heated sealing roller pair (9) in order to provide the sealed longitudinal seam (2) between the two layers (6, 7), and an unheated conveyor roller pair (10) arranged downstream of the sealing roller pair (9) when seen in the running direction (L). The sealing roller pair (9) comprises two sealing rollers (9a, 9b), a sealing lateral face (17) of which contacts the packaging material (3), and the conveyor roller pair (10) comprises two conveyor rollers (10a, 10b), a conveyor lateral face (18) of which contacts the packaging material. The sealing lateral face (17) of the sealing roller pair (9) is offset relative to the conveyor lateral face (18) in a direction (S) perpendicular to the transport plane.