Thermoplastic Resin Composite Bonding via Wavy Linking Parts
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Solution Overview
Problem
Conventional methods for producing large fiber-reinforced thermoplastic resin composite components result in high facility and running costs, increased weight due to metal fasteners, and insufficient welding strength, while existing welding techniques do not allow for flat connections with sufficient strength and stiffness.
Innovation Solution
A resin composite structure is created by bonding members with randomly oriented and intertwined discontinuous fibers, using a method that involves forming linking parts and non-overlapping spaces, applying a load to fill the spaces, and thermally softening the linking parts to integrate the members, allowing for flat connections with enhanced strength and stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If members are connected using metal fasteners (nuts and bolts or rivets), then the connection is mechanically strong, but the weight of the component is increased and operating costs are high due to boring and fastening operations
Solution Approach 1:
The patent replaces the mechanical fastening system (metal fasteners, nuts, bolts, rivets) with a thermal bonding system. The members are heated to melt the thermoplastic resin at the connection portion, and the molten resin is pressed to bond the members together. This substitution eliminates the need for metal fasteners and associated mechanical operations (boring, fastening), thereby reducing component weight and operating costs while maintaining connection strength.
Solution Approach 2:
The patent changes the physical state of the thermoplastic resin from solid to liquid by heating it to the melting point. This parameter change (temperature increase) enables the resin to flow and fill the connection region, creating a strong bond between members. After bonding, the resin cools and solidifies, forming a rigid connection that replaces metal fasteners.
2Reliability
If a large scale molding apparatus is used to produce the entire component in one molding process, then the component integrity is high, but the facility cost and running cost are high
Solution Approach 1:
The patent divides the large component into multiple separate members that are produced individually using standard-sized molding apparatus. These members are then connected through thermal bonding at connection portions. This segmentation allows the use of smaller, more cost-effective molding equipment while maintaining overall component integrity through the bonded connections.
Solution Approach 2:
The members are prepared with connection portions (such as protrusions or recesses) during the molding process, before the actual assembly. This preliminary action ensures that when the members are later heated and bonded, the connection portions align properly and the bonding process is efficient, maintaining component integrity without requiring expensive large-scale molding apparatus.
3Ease of manufacture
If conventional welding methods (thermal welding, vibration welding, ultrasonic welding, or laser welding) are used to connect members, then the connection process is simplified, but the welding strength is insufficient
Solution Approach 1:
The patent uses heating to change the temperature parameter of the thermoplastic resin to its melting point, transforming it from a solid to a liquid state. This allows the resin to flow and fully penetrate the connection region, creating strong intermolecular bonds. After bonding, cooling solidifies the resin, forming a rigid connection. This parameter change approach achieves both process simplicity and high welding strength.
4Strength
If the welding method from Japanese Laid-Open Patent Publication No. 11-090986 is used to achieve excellent appearance and high welding strength, then the connection strength is improved, but the component cannot have a flat shape and the connection has large thickness increasing weight
Solution Approach 1:
The patent applies local quality by concentrating the bonding action at the connection portions (protrusions or recesses) rather than across the entire member surface. The heating and pressing are localized to these specific regions, allowing the rest of the member surfaces to remain flat. This localized approach maintains both connection strength and overall component flatness.
Solution Approach 2:
The patent uses protrusions or recesses (adding a third dimension) at the connection portions to enable effective bonding. These three-dimensional features allow the molten resin to flow into and fill the connection region, creating strong bonds. The protrusions/recesses are localized features that do not prevent the overall member surfaces from being flat, thus resolving the contradiction between connection strength and shape flatness.
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 produces a lightweight resin composite structure with sufficient bonding strength and stiffness, enabling flat connections and reducing weight and operational costs, while avoiding the limitations of conventional welding techniques.
Implementation Method 1
the members first are heated and melted such that the reinforcing fiber is partially exposed on the surface of the connection, and thereafter, the melted members are press-molded and welded
Implementation Method 2
a heating step of thermally softening at least the linking part, before the overlapping step, after the overlapping step, or during the bonding step
Data Source
AI summary
Linking parts are formed on one end of a first resin composite member and on one end of a second resin composite member in order to bond the ends together. For example, the linking parts may be wavy parts containing concave portions and convex portions. In this case, the wavy parts initially are heated and softened. Then, in a molding unit, respective pairs of confronting convex portions are overlapped with each other, and respective pairs of confronting concave portions are utilized to form a non-overlapping space. The overlapped convex portions are pressed and crushed, such that a base thermoplastic resin and fibers contained therein flow toward the non-overlapping space. Thereafter, the thermoplastic resin is cooled and hardened, whereby the first resin composite member and the second resin composite member are bonded integrally to obtain a resin composite structure.