Pedelec Frame Laser Welding and Composite Material
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Solution Overview
Problem
Pedelec frames face challenges in achieving high load capacity, aesthetic appeal, and reduced weight due to the integration of electric motors and batteries, often requiring larger diameters and heavier metal components, which conventional plastic materials lack in resilience and stability.
Innovation Solution
A method involving the use of partially aromatic polyamide-based fiber-reinforced thermoplastic for producing pedelec frames by joining two mirror-image plastic half-shells, allowing for integrated component positioning and laser welding, which eliminates the need for adhesives and enhances rigidity, stability, and aesthetic appeal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If conventional plastic materials are used for pedelec frames, then weight is reduced, but resilience and stability are insufficient
Solution Approach 1:
The patent uses fiber-reinforced thermoplastic composite materials, specifically incorporating glass fibers or carbon fibers into the plastic matrix. This composite structure provides both the weight reduction benefits of plastic and the strength/resilience of fiber reinforcement, resolving the contradiction between lightweight construction and structural integrity for pedelec frames
2Ease of manufacture
If two plastic half-shells are joined using adhesive methods, then manufacturing is simplified, but curing time increases production time
Solution Approach 1:
The patent replaces chemical adhesive bonding with laser welding technology. The laser beam directly melts and fuses the plastic half-shells without requiring adhesives or curing time, maintaining manufacturing simplicity while eliminating the time-consuming adhesive curing process
Solution Approach 2:
The laser welding process utilizes phase transitions of the thermoplastic material - the laser energy heats the plastic above its melting point, causing it to melt and fuse the half-shells together. Upon cooling, the material solidifies to create a strong joint, eliminating the need for adhesive curing time
3Adaptability or versatility
If frame tubes are made with larger diameter to accommodate supply elements, then component storage is enabled, but aesthetic appeal deteriorates
Solution Approach 1:
The patent designs the pedelec frame as two nested half-shells with an internal cavity between them. This nested structure provides space for accommodating battery elements and other supply components within the frame itself, eliminating the need for external attachments and maintaining aesthetic appeal
4Strength
If pedelec frames are made from metal components, then load capacity is sufficient, but weight increases
Solution Approach 1:
The patent employs fiber-reinforced thermoplastic composites that combine the low weight of plastic with the high strength of fiber reinforcement (glass or carbon fibers). This composite material achieves sufficient load capacity for pedelec applications while maintaining significant weight advantages over traditional metal frame construction
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 results in lightweight, high-quality pedelec frames with improved thermal resistance and dimensional stability, enabling efficient storage of electric components and reducing the need for heavy metal components, while maintaining structural integrity and aesthetic appeal.
Implementation Method 1
the joining edge of the other half-shell is irradiated by a laser, so that the plastic is melted
Implementation Method 2
the joining edge of the other half-shell is irradiated by a laser, so that the plastic is melted
Data Source
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AI summary
The invention relates to a method for manufacturing a plastic pedelec frame (1) by, preferably integrally, joining two matching plastic half-shells (2, 3), said pedelec frame (1) being provided with receptacles (12, 13, 14) for a handlebar (4), a bottom bracket (5) and preferably a seat (6). The two plastic half-shells (2, 3) are made from a fiber-reinforced thermoplastic material containing a partially aromatic polyamide, using an injection molding process. The invention also relates to a pedelec frame (1) manufactured by said method.