Lateral Sonotrode for Plastic Friction Welding
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Solution Overview
Problem
The existing methods for welding plastic bags are inefficient, leading to poor quality welded joints due to product residues and require lengthy, space-consuming processes, making them expensive and time-consuming.
Innovation Solution
A sonotrode with a laterally arranged working surface that introduces joining energy adapted to the shape of the second joining part, allowing for friction welding of plastic parts without axial contact, ensuring reliable connections and eliminating local over/underwelding issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat welding with double heating and separate cooling is used, then welded joints can be formed, but the production machine becomes long and space-consuming, and welding time increases
Solution Approach 1:
The patent combines heating and cooling functions into a single welding station by using a through-conveying mold that allows the filled form to be cooled during the heating process. This eliminates the need for separate heating and cooling sections, reducing machine length and improving productivity while maintaining reliable welded joints.
Solution Approach 2:
The welding process is made continuous by implementing simultaneous heating and cooling operations. The filled form is cooled in the mold cavity while being heated at the welding surface, allowing both processes to occur concurrently rather than sequentially, thereby reducing total cycle time and increasing production efficiency.
2Ease of manufacture
If heat welding is performed after filling, then joining parts can be attached, but product residues accumulate at welding points, negatively affecting joint formation
Solution Approach 1:
The patent performs preliminary cooling of the filled form in the mold cavity before the welding operation. This pre-cooling step solidifies the product and prevents it from migrating to the welding zone during subsequent heating, ensuring clean welding surfaces and reliable joint formation while maintaining ease of manufacturing.
3Power
If ultrasonic welding is performed axially, then joining energy can be introduced, but local overheating occurs at the tip, causing material deterioration
Solution Approach 1:
The patent transitions from axial ultrasonic welding to lateral (tangential) welding, where the sonotrode acts on the side of the filled form rather than from the top. This dimensional change distributes the joining energy across a larger surface area, preventing localized overheating and material deterioration while maintaining effective power transmission for reliable welding.
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 method provides reliable, hygienic, and fast welding connections even with product residues, reducing maintenance and space requirements, and eliminates the need for separate cooling steps, resulting in a cost-effective and efficient process.
Implementation Method 1
friction welding of at least two parts to be joined, which at least partially consist of weldable plastic
Implementation Method 2
sonotrode for friction welding... which can be stimulated to vibrate
Data Source
Figure 1
Figure 2
Figure 3A~3
AI summary
A sonotrode (30) according to the invention for friction welding of at least two joining parts, which consist at least partially of weldable plastic, comprises a longitudinal axis along which the sonotrode (30) can be deflected during operation, a working surface which is arranged laterally on the sonotrode (30) with respect to the longitudinal axis, so that joining energy can be introduced laterally into a joining zone between a first and a second joining part (10), and which can be applied to the first joining part during operation, wherein the working surface has a first structure whose shape can be adapted to a shape of at least the second joining part (10).