Thermoplastic Joining Element Anchoring for Reproducible Assembly
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Solution Overview
Problem
Existing methods for joining objects using thermoplastic materials face challenges in controlling the flow characteristics and achieving reproducible results, especially when the properties of the objects to be joined are unpredictable.
Innovation Solution
A method involving a joining element with thermoplastic properties, where mechanical vibration is applied to anchor the element into blind holes of the objects, allowing the thermoplastic material to flow into the object's structure, forming a well-defined connection independent of the objects' properties, and optionally using a sonotrode or other vibration sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thermoplastic material is used for joining elements, then the joining process can be simplified and assembly stability is achieved, but controlling the flow characteristics and achieving reproducible results becomes difficult when object properties are unpredictable
Solution Approach 1:
The patent applies parameter changes by modifying the physical state of the thermoplastic material through temperature control. The joining element includes a thermoplastic material that transitions from a solid state during insertion to a molten state during joining, allowing it to flow into the workpiece and form a reliable connection. This phase transition enables reproducible results regardless of workpiece material properties, as the molten thermoplastic can adapt to any surface geometry and solidifies to create a strong bond.
2Reliability
If asymmetric joining elements are used to achieve similar anchorage qualities, then joining reliability improves, but device complexity and process difficulty increase
Solution Approach 1:
The patent applies local quality by creating an asymmetric joining element where the thermoplastic material is concentrated at the distal end rather than being uniformly distributed. This localized concentration of thermoplastic material at the working end allows the element to achieve reliable anchorage in the workpiece while simplifying the overall design compared to fully asymmetric configurations. The local quality approach enables consistent performance without requiring complex asymmetric geometries throughout the entire joining element.
3Productivity
If ultrasonic vibration is applied to liquefy thermoplastic material, then joining efficiency and productivity improve, but energy consumption increases
Solution Approach 1:
The patent applies periodic action by using ultrasonic vibration to intermittently liquefy and solidify the thermoplastic material during the joining process. The ultrasonic energy is applied in a periodic manner, causing the thermoplastic to melt during vibration cycles and solidify during non-vibration cycles. This periodic action enables efficient joining by repeatedly softening the material to allow flow into the workpiece and then hardening it to create the bond, achieving high productivity with controlled energy input.
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 provides reproducible and well-defined fixations, enabling immediate assembly stability without delaying the manufacturing process, suitable for various materials and applications, including furniture, building, and automotive industries.
Implementation Method 1
the application of energy, such as mechanical vibration, e.g. ultrasonic vibration
Implementation Method 2
at least part of the material having thermoplastic properties is liquefied where the joining element ends are pressed against the bottom faces of the holes
Implementation Method 3
the liquefied material is caused to infiltrate into pores of the hole surfaces or unevennesses or openings provided in the hole surfaces
Data Source
AI summary
A tool presses a joining element against a first object into a first opening of the first object while mechanical vibration energy is coupled into the first object and the joining element. Vibration energy and pressing force make the thermoplastic material of the distal portion of the joining element flowable and interpenetrates structures of the first object to yield, after re-solidification, an anchoring of the distal portion of the joining element in the first object. The second object is placed so that a proximal portion of the joining element is inserted into a second opening, and the first and second objects are pressed against each other while mechanical vibration energy is coupled into one of the first and second objects, until thermoplastic material of the joining element proximal portion is made flowable and interpenetrates structures of the second object to yield, after re-solidification, an anchoring in the second object.