Sonotrode Anvil Welding Contact Elements for Plastic Containers
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Solution Overview
Problem
Existing ultrasonic welding techniques for plastic containers with blow-moulded surfaces, particularly those produced via stretch blowing, face challenges in achieving strong weld seams due to concentric wall thickness differences, leading to uneven compression loads and inadequate weld strength, which limits customization and filling capacity.
Innovation Solution
A combination of a sonotrode and an anvil with specifically designed welding contact elements, featuring alternating alignments and curved surfaces, that increase the welding contact surface area and penetrate the plastic layers effectively, ensuring a strong and uniform weld seam even with varying wall thicknesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If flat pressing systems are used for sealing blow-moulded plastic containers, then the sealing process is simple, but uneven compression load occurs due to concentric wall thickness differences, resulting in insufficient weld seam strength
Solution Approach 1:
The sonotrode and anvil surfaces are segmented into multiple welding contact elements arranged in rows and columns, with each element having a specific geometry (plateau surface with lateral surfaces at defined angles). This segmentation allows localized pressure distribution across different wall thickness zones, enabling effective welding of blow-moulded containers with concentric wall thickness variations.
Solution Approach 2:
The welding contact elements are designed with specific local geometries including plateau surfaces and lateral surfaces at defined angles (e.g., 45° to 90°), creating localized high-pressure zones that adapt to varying wall thicknesses. This local quality enhancement ensures adequate penetration and weld seam strength in areas with thinner walls while preventing excessive pressure in thicker wall regions.
2Strength
If projections with small pressurised area are used to break heat-resistant layers, then the welding unit can create weld seams, but only a very small pressurised area is achieved, limiting weld seam structure options
Solution Approach 1:
The welding contact elements extend in multiple dimensions with defined lengths, widths, and heights, and lateral surfaces at specific angles. This multi-dimensional geometry creates extended pressurized areas that penetrate through the container walls more effectively than simple projections, enabling robust weld seams while maintaining adaptability to wall thickness variations.
3Productivity
If hot stamping is used for sealing, then the sealing process is straightforward, but the tube cannot be filled to sufficient height due to hot stamp application requirements
Solution Approach 1:
The patent replaces thermal sealing (hot stamping) with ultrasonic welding, which uses mechanical vibrations converted to heat through direct contact between welding elements and the plastic material. This substitution eliminates the need for hot stamp application, allowing the container to be filled to maximum height while maintaining reliable seal integrity through ultrasonic welding of the rim.
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 provides a robust weld seam structure that resists splitting under pressure changes and allows for greater filling capacity, enhancing the durability and functionality of plastic containers.
Implementation Method 1
ultrasonic welding allows thermoplastic plastics to be joined together. With ultrasonic welding mechanical vibrations are converted into heat as a result of which the plastic layers undergo molecular melting
Implementation Method 2
mechanical vibrations are converted into heat as a result of which the plastic layers undergo molecular melting
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
Combination of a sonotrode (1) and anvil (20), comprising a sonotrode/anvil surface (3, 21) and a first row of sonotrode/anvil welding contact elements (4, 22), whereby aforesaid first/second series of each aforesaid sonotrode/anvil welding contact element of a first row (11, 30) comprises a first/second adapted lateral surface (12, 31) that joins at least one part of aforesaid first/second plateau surface (9, 27) with at least one part of aforesaid sonotrode/anvil surface side (5, 23), whereby aforesaid first/second adapted lateral surface (12, 31) comprises a first/second curved surface (13, 32) positioned between aforesaid first/second plateau surface (9, 27) and aforesaid first/second substantially straight surface (14, 29), whereby aforesaid first/second curved surface (13, 31) has a convex outward arch. The welding contact element (4) is positioned in relation to aforesaid anvil welding contact element (22) such that aforesaid sonotrode welding contact element (4) is positioned during welding next to aforesaid anvil welding contact element (22) and is provided to form at least one part of a weld seam (80).