Plastic Bicycle Frame Injection Molding with Fluid Displacement
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Solution Overview
Problem
Existing plastic bicycle frames made using Resin Transfer Moulding (RTM) are difficult to recycle, and the injection molding process is complicated by the frame's complex geometry and hollow pipes.
Innovation Solution
A procedure for producing a plastic frame for two-wheelers involves injecting a thermoplastic plastic melt into a closed injection molding tool, followed by the injection of a fluid to displace the plastic melt and create cavities, allowing for faster cooling and reduced production time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermosetting matrix material is used for manufacturing bicycle frames via RTM, then the frame achieves structural integrity and rigidity, but the material cannot be effectively recycled
Solution Approach 1:
The patent changes the material parameter from thermosetting to thermoplastic matrix material. This fundamental parameter change enables recyclability while maintaining frame rigidity through the thermoplastic material's mechanical properties and fiber reinforcement structure.
Solution Approach 2:
The patent uses composite materials consisting of thermoplastic matrix material combined with glass and/or carbon fiber fabric. This composite structure provides both the required structural integrity and rigidity while enabling recyclability through the thermoplastic component.
2Weight of moving object
If the injection molding process is used to manufacture frames with complex geometry and hollow tubes, then the frame achieves lightweight design and cost-effectiveness, but the manufacturing process becomes complicated
Solution Approach 1:
The patent introduces a fluid injection system as a secondary process step after plastic injection. The fluid is injected through injectors to displace the plastic core and form hollow cavities within the frame tubes, achieving the desired tubular cross-section without complex mold designs.
Solution Approach 2:
The patent performs preliminary plastic injection to fill the mold cavity, then subsequently injects fluid to create the hollow structure. This two-stage approach simplifies the overall manufacturing process by separating the forming and cavitation steps.
3Strength
If solid plastic material is used for frame manufacturing, then the frame achieves structural strength, but the cooling time during manufacturing is significantly extended
Solution Approach 1:
The patent uses fluid injection to create hollow cavities within the frame structure. This reduces the volume of plastic material that needs to be cooled, significantly shortening the cooling time while maintaining frame strength through the tubular cross-section geometry.
Solution Approach 2:
The patent transitions from solid to hollow tubular cross-sections, adding a dimensional aspect (internal cavity) to the frame structure. This dimensional change reduces material volume and cooling requirements while maintaining or improving structural strength through the tubular geometry.
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 enables the production of lightweight, cost-effective two-wheeler frames with improved rigidity, while also allowing for the potential recycling of the plastic material.
Implementation Method 1
injecting a fluid to displace the plastic core from the component cavity
Implementation Method 2
maintaining the fluid pressure inside the component for at least a short time
Implementation Method 3
the cooling phase of the hot plastic melt can be significantly shortened
Data Source
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AI summary
The invention relates to a method for producing a plastic frame for a two-wheeled vehicle by means of plastic injection molding, said plastic frame having at least one cavity in the interior, said method comprising a series of steps, wherein, after a preferably thermoplastic plastic melt has been injected into a closed injection-molding tool, a fluid is injected in order to displace the plastic core out of the component cavity.