Braking Device for Transverse Welding of Elastic Composite Tapes
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Solution Overview
Problem
The existing methods for producing transverse welds in composite tapes for sanitary products, such as training pants, face limitations in operation speed due to the need for adequate sealing force and consistent angular positioning of welds, which affects the quality and efficiency of the welding process.
Innovation Solution
A method and apparatus that involve a braking device to reduce the speed of the composite tape after folding, allowing for a higher number of ultrasonic blows per unit length, thereby improving the quality and consistency of transverse welds while enabling higher production speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the tape passes through the welding system at high speed, then productivity is improved, but the number of ultrasonic blows per unit length decreases, worsening weld quality
Solution Approach 1:
The patent applies a braking device that dynamically adjusts the tape speed before the welding station. The tape is fed at high speed through most of the production line, then temporarily decelerated only in the welding zone to ensure adequate ultrasonic blows per unit length, and then accelerated again. This dynamic speed adjustment resolves the contradiction by allowing high overall productivity while maintaining weld quality in the critical welding region.
2Manufacturing precision
If the tape speed is reduced to improve weld quality, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The patent implements local speed reduction only at the welding station rather than reducing the speed of the entire production line. The braking device creates a localized deceleration zone that affects only the tape portion being welded, allowing high-speed operation elsewhere in the system. This local approach to speed control maintains weld quality while preserving overall productivity.
3Strength
If the number of ultrasonic blows is increased to ensure adequate sealing force, then weld strength is improved, but the time required per weld increases, reducing productivity
Solution Approach 1:
The braking device performs a preliminary action by pre-decelerating the tape before it enters the welding zone. This prepares the system to deliver the required number of ultrasonic blows at the correct speed, ensuring adequate sealing force and weld strength. The preliminary speed adjustment prevents the need for excessive blows that would otherwise be required to compensate for high-speed passing, thus maintaining strength while improving productivity.
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 enhances the tensile strength of transverse welds, ensuring a safe and reliable closure of the sanitary articles while allowing for faster production without compromising weld quality, thus addressing the limitations of existing technologies.
Implementation Method 1
the welding is carried out by repeatedly striking, with a strong intensity, the layers of material interposed between the vibrating device of the ultrasonic system and the respective counter-roller
Implementation Method 2
Due to the repeated blows, the material of the tape interposed between the welding pattern and the vibrating element of the ultrasonic system decreases in thickness by compressing and moving toward the side edges of the protuberances of the counter-roller, generating the heat necessary to melt all the layers of material
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A method for producing sanitary articles of the pre-fastened type in the form of pants (10, 10') that involves the transverse welding of a composite tape (100, 100') formed of at least two overlapping elastic structures (1a, 1a', 1b, 1b'), which continuously advance in a longitudinal direction (MD) at a first feeding speed (V1) and at a first feed tension (T1) ; - slowing down (70) said composite tape (100, 100'), taking it to a second speed (V2) and a second tension (T2), respectively less than said first feeding speed (V1) and said corresponding first feed tension (T1), - feeding said composite tape (100, 100') at said second speed (V2) and tension (T2) to a welding station (80) and welding (80) said composite tape (100, 100') with welding lines (13) transverse to said longitudinal feed direction (MD), and - feeding said composite tape (100, 100') at said second speed (V2) and tension (T2) to a cutting station (90) and - cutting (90) said composite tape (100, 100') with cuts (12) transverse to said longitudinal feed direction (MD).