Thermoplastic-to-Sheet Edge Bonding by Friction Embedding
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Solution Overview
Problem
The challenge in the automotive, aviation, and other industries is to achieve a reliable and cost-efficient mechanical connection between thermoplastic parts and non-liquefiable materials, particularly when dealing with temperature fluctuations and varying coefficients of thermal expansion, as traditional adhesive bonds are unreliable and costly, and mechanical fasteners face precision issues with large or complex parts.
Innovation Solution
A method involving a thermoplastic material in a solid state, where a second object with a flat sheet portion and edge is positioned relative to the first object, and a rotational movement generates friction heat to melt the thermoplastic, embedding the edge within it, forming a strong and reliable connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive bonds are used to connect thermoplastic parts to metal parts, then the bonding can be light and strong, but the reliability cannot be controlled long-term and manufacturing costs rise due to slow hardening processes
Solution Approach 1:
The patent replaces adhesive bonding (chemical/mechanical system) with friction-induced melting and embedding (thermal-mechanical system). The thermoplastic material is melted by friction heat generated during relative movement and embeds the edge of the metal sheet, creating a mechanical interlocking connection that is both strong and controllable, eliminating the slow hardening process of adhesives.
Solution Approach 2:
The patent utilizes the phase transition of thermoplastic material from solid to melted state through friction heat, allowing the material to flow and embed the metal sheet edge, then transitions back to solid state upon cooling, creating a reliable mechanical bond without the time-consuming hardening process of adhesives.
2Reliability
If mechanical fasteners such as screws and nuts are used, then the connection is reliable, but precise definition of relative locations is required which is hard to reach with large parts and tolerance compensation issues
Solution Approach 1:
The patent changes the connection mechanism from rigid mechanical fastening requiring precise positioning to a process where thermoplastic material undergoes phase change and flows to embed the metal edge. This allows tolerance compensation as the material adapts to positional variations during the embedding process, maintaining connection reliability without requiring high positioning precision.
Solution Approach 2:
The thermoplastic material acts as an intermediary between the metal sheet and the connection point. During the bonding process, it melts and flows to accommodate tolerance variations, then solidifies to create a reliable mechanical interlocking connection, effectively mediating the positioning precision issue.
3Strength
If adhesive bonds are used for flattish objects with different coefficients of thermal expansion, then bonding is achieved, but substantial shearing forces occur due to temperature fluctuations reducing reliability
Solution Approach 1:
The patent creates a localized embedding connection where the thermoplastic material surrounds and mechanically interlocks with the metal sheet edge. This localized mechanical interlocking is resistant to shearing forces from thermal expansion differences, as the embedded edge acts as an anchor point that accommodates thermal movement without compromising bond integrity.
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 a quick, efficient, and reliable mechanical connection with reduced axial joining forces, suitable for lightweight materials, enhancing bonding strength and control, while minimizing material and manufacturing costs.
Implementation Method 1
a melting zone including flowable thermoplastic material is formed and such that thermoplastic material of the melting zone flows around the edge
Implementation Method 2
bringing the first object and the second object to a relative movement to each other such that a melting zone including flowable thermoplastic material is formed
Data Source
AI summary
The relates to a method of mechanically securing a first object to a second object and includes the steps of: providing the first object including thermoplastic material in a solid state, providing the second object with a generally flat sheet portion having an edge, positioning the first object relative to the second object and bringing the first object and the second object to a relative movement to each other. The relative movement includes a rotational movement, such that a melting zone including flowable thermoplastic material is formed and such that thermoplastic material of the melting zone flows around the edge to at least partially embed the edge in the thermoplastic material. The invention further concerns a connector that is suitable for being used in a method according to the invention.