Strapping Apparatus Variable Cooling Time for Seal Strength
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Solution Overview
Problem
Friction-welded band seals produced by mobile strapping apparatuses often lack sufficient tensile strength, especially with thicker and wider straps, despite adjusting welding time.
Innovation Solution
A variable cooling time period is implemented after welding, dependent on the band tension, allowing the heated material more time to cool and solidify, which enhances the seal's load-bearing capacity, and this is automatically determined by the strapping apparatus using an algorithm considering tensioning force and welding time settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding time is increased to improve seal strength, then tensile strength of seal is improved, but productivity decreases due to longer processing time
Solution Approach 1:
The sealing process is divided into two distinct phases: welding phase and cooling phase. The welding phase melts the band layers through friction, while the cooling phase allows the melted material to solidify and form a strong seal. This segmentation allows optimization of each phase independently, ensuring sufficient cooling time for strength while maintaining overall productivity.
Solution Approach 2:
The cooling time is predetermined and automatically applied after welding based on the band tension settings. By pre-calculating the required cooling duration during the welding phase, the system ensures adequate solidification time without requiring extended total processing time, thus maintaining productivity while achieving sufficient seal strength.
2Strength
If cooling time is extended to improve seal quality, then load-bearing capacity is improved, but productivity decreases due to longer cycle time
Solution Approach 1:
The cooling time is dynamically adjusted based on the band tension settings rather than being a fixed value. The control unit automatically selects appropriate cooling durations from predetermined values corresponding to different tension levels. This dynamic adaptation ensures optimal cooling time for each specific application, maximizing seal strength while minimizing unnecessary cycle time extensions.
Solution Approach 2:
The system incorporates feedback from the band tension detection to automatically determine the appropriate cooling time. The control unit receives information about the applied tension and uses this feedback to select the optimal cooling duration, ensuring that each seal receives adequate cooling time for its specific load requirements without unnecessarily extending the overall cycle time.
3Strength
If band tension is increased to improve seal strength, then tensile strength is improved, but reliability decreases due to higher risk of band breakage
Solution Approach 1:
The system applies beforehand cushioning by implementing a predetermined cooling period after welding during which the band remains clamped. This cooling period allows the melted material to solidify and gain strength gradually, cushioning against sudden stress concentrations that could cause band breakage. The gradual solidification process reduces thermal shock and stress, improving reliability while maintaining seal strength.
Solution Approach 2:
The system changes parameters dynamically by adjusting cooling time based on band tension levels. For higher tension applications, longer cooling periods are automatically applied to allow thorough solidification and stress relief. This parameter adaptation ensures that the band and seal can withstand the applied tension without failure, maintaining both strength and reliability across different operating conditions.
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 solution significantly reduces seal failures and optimizes the number of strappings by adapting the cooling time to match the applied band tension, improving the strength and quality of the seals.
Implementation Method 1
a seal is produced between the two band layers by friction welding at the loop. In this connection, pressure is applied to the band in the region of two ends of the band loop by a fraction shoe moving in an oscillating manner. The pressure and the heat arising because of the movement melt the band, which generally contains plastic, locally for a short time.
Implementation Method 2
a cooling time period for the seal, during which the strapping apparatus keeps the strapping band clamped following a welding time, is variable depending on the band tension which is variably adjustable at the strapping apparatus. The longer cooling time means that the material heated during the friction welding also has a longer time to cool and to solidify, which contributes to an increase in the load-bearing capacity of the seal.
Data Source
AI summary
A strapping apparatus for strapping articles with a strapping band having a base plate provided for arranging on an article, a tensioning device with which a band tension can be applied to the strapping band, and a sealing device for permanently connecting two band layers to each other.