Dual-Maximum Sealing Force Curve for Tubular Film
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Solution Overview
Problem
Existing methods for generating welding force in vertical tubular bagging machines are inefficient in terms of energy usage and system design, as they apply unnecessarily high sealing forces during the heating process, leading to excessive energy expenditure and equipment load, and result in suboptimal weld quality due to inappropriate pressure profiles.
Innovation Solution
A sealing method with a dual-maximum sealing force curve, where the force initially rises to a lower maximum, remains constant, and then increases to a higher maximum, allowing for efficient energy use and reduced drive power requirements, with the higher force applied briefly to achieve high weld quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high sealing force is applied continuously during the heating process, then the weld quality is improved, but the energy consumption increases and the drive system becomes more expensive
Solution Approach 1:
The sealing force is applied periodically in two distinct phases: a first phase with lower sealing force during heating, and a second phase with higher sealing force after the film reaches melting temperature. This periodic application of force matches the thermal process stages, providing high force only when needed for welding while reducing force during heating to minimize energy consumption.
Solution Approach 2:
The sealing force parameter is dynamically changed based on the thermal state of the film. The control system adjusts the sealing force from a first level (sufficient for heat transfer) to a second level (sufficient for welding) based on temperature feedback or time-based control, optimizing the force application to match the material's thermal and mechanical state throughout the sealing process.
2Manufacturing precision
If high sealing force is applied continuously, then the weld quality is improved, but the drive system design becomes more complex and expensive
Solution Approach 1:
The drive system is designed to provide high torque only during the brief second phase when high sealing force is needed, rather than continuously. This allows the use of lighter, less expensive drive components that are sized for peak rather than continuous high-force requirements, reducing system complexity and cost while maintaining weld quality.
3Stability of the object's composition
If high sealing force is applied during heating, then the film is compressed, but unnecessary drive energy is expended and the plastic material may be displaced from the welded joint
Solution Approach 1:
The sealing force is applied in two periodic phases: first a lower force during heating that provides sufficient compression for heat transfer without excessive displacement, then a higher force after melting begins to ensure proper welding. This periodic application reduces energy loss by matching force magnitude to the actual needs of each process stage.
Solution Approach 2:
The sealing force parameter is adjusted based on the thermal state of the film. During heating, a lower force parameter is used that provides adequate compression for thermal conduction without causing excessive material displacement. After the film reaches melting temperature, the force parameter is increased to ensure proper welding of the softened material.
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 reduces energy consumption, allows for a lighter and cheaper drive system, and produces high-quality welds by optimizing the sealing force profile, ensuring efficient energy use and improved weld quality with reduced system costs.
Implementation Method 1
heat the tubular film to a temperature at which the material of the tubular film is at least partially melted
Implementation Method 2
Only a relatively low sealing pressure is required to heat the film tube. Only when the tubular film has reached a temperature such that it is at least partially plasticized does the sealing force have to be increased
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a method for generating a welding force or welding pressure for a sealing jaw (1, 6), in particular a sealing jaw (1, 6) of a transverse sealing station (2) of a vertical form-fill-seal machine (3), wherein the sealing jaw (1, 6) is moved circumferentially or back and forth along a closed web (4) or along a linear web (29) in order to abut against a resistance, in particular a second, counter-rotating sealing jaw (1, 6), wherein a film tube (7) is compressed between the resistance and at least one sealing surface (30) of the sealing jaw (1, 6) in order to seal the film tube (7) by means of heat introduced into the film tube (7) via the sealing surface (30) at an applied pressure in a sealing plane (S) under a sealing force (Fs) within a sealing time (ts), and wherein at least one drive (8, 9) is provided for moving the sealing jaw (1,6) to move in a normal direction to a surface of the resistance in order to carry out the welding process in a stationary position or along an effective sealing path (Zseff) within the sealing time (ts), and wherein the sealing force (Fs) or a sealing parameter correlated with the sealing force (Fs), in particular the sealing pressure or the drive power of the drive (8, 9), is specified by a control device (27) during the sealing time (ts) such that the sealing force (Fs) within the sealing time (ts) follows a sealing force curve (32), wherein the sealing force curve (32) has a first relative sealing force maximum (33) with a sealing force (Fs1) and at least a second relative sealing force maximum (34) with a sealing force (Fs2), wherein the sealing force (Fs2) is higher than the sealing force (Fs1) at the second sealing force maximum (34). at the first maximum sealing force (33).,