Two-Wheeled Vehicle Head Pipe Molding for Stiffness and Weight Reduction
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Solution Overview
Problem
Conventional body frames of two-wheeled vehicles, particularly those with forged head pipes, face challenges in achieving a balance between stiffness and lightweight design due to unwanted thick regions that increase weight, necessitating cumbersome manufacturing processes to cut these regions.
Innovation Solution
A body frame design featuring a head pipe manufactured by molding, with an upper and lower head pipe configuration that supports the main frame and down tube, respectively, allowing for separate molding and coupling to achieve stiffness and light weight without the need for cutting thick regions, using dies divided into parts for forging to form concave and channel-shaped sections for enhanced coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the head pipe is manufactured by forging with a die divided into parts, then the structural complexity is reduced and manufacturing becomes easier, but unwanted thick regions are created that increase weight
Solution Approach 1:
The die is divided into multiple parts (first die part and second die part) that can be separately configured and assembled. This segmentation allows precise control over the molding process to eliminate unwanted thick regions while maintaining ease of manufacture through modular die construction.
Solution Approach 2:
The die parts are designed with different local characteristics - the first die part forms the upper head pipe with specific thickness distribution, while the second die part forms the lower head pipe with different thickness requirements. This local quality differentiation ensures optimal weight distribution and structural integrity without uniform thickness throughout.
2Strength
If the head pipe is made stiffer through extended welding length, then the structural strength is improved, but the manufacturing time and complexity increase
Solution Approach 1:
The upper and lower head pipes are pre-formed with optimized geometries during the molding process before assembly. The die parts are designed to create pre-stressed structures that enhance strength without requiring extended welding lengths, thus maintaining productivity.
Solution Approach 2:
The head pipe assembly combines different material properties in the upper and lower portions through the multi-part die molding process, creating a composite structure that achieves enhanced strength through material differentiation rather than extended welding.
3Device complexity
If the main frame tongue portion and down tube tongue portion are forged as single pieces, then the manufacturing process is simplified, but the weight increases due to unwanted thick regions
Solution Approach 1:
The die is segmented into multiple parts that can be independently configured to form different portions of the head pipe. This allows the main frame tongue portion and down tube tongue portion to be formed with optimized, variable thickness profiles rather than uniform thickness, reducing weight while maintaining structural integrity.
Solution Approach 2:
The molding process uses dynamic die part configuration where the first and second die parts can be positioned and adjusted to create varying thickness distributions in the head pipe sections. This dynamic control during molding eliminates static, uniform thickness and creates optimized weight distribution.
Data Source
AI summary
A body frame of a two-wheeled vehicle. The body frame typically includes a head pipe to which a steering shaft extending substantially vertically is rotatably mounted. The head pipe includes an upper head pipe and a lower head pipe that are configured to be molded and to be coupled to each other. The upper head pipe includes an upper tubular portion into which the steering shaft is inserted and a main frame tongue portion that is configured to extend rearward from the upper tubular portion and is configured to support a front portion of the main frame from above. The lower head pipe includes a lower tubular portion into which the steering shaft is inserted and a down tube tongue portion that is configured to extend downward from the lower tubular portion and to support an upper portion of the down tube from forward.