Stamped Locking Arm Structure for Fracture-Resistant Carrier Rods
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Solution Overview
Problem
The existing manufacturing process for bicycle carrier connecting rods is costly and time-consuming due to mechanical cutting, and the locking arm is prone to fractures from shear stress during transportation due to precise perforations and positioning holes at the bend.
Innovation Solution
A method involving stamping dies to form a locking arm with arc-shaped protrusions and conical positioning holes, reducing material waste and requiring no specialized tools, combined with plastic molding for an L-shaped stopper, enhancing structural strength and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical cutting is used to manufacture the locking arm, then the locking arm can be produced with precise dimensions, but the processing time and cost increase significantly
Solution Approach 1:
The patent replaces the traditional mechanical cutting process with a stamping process. The locking arm is formed by stamping a metal sheet using a stamping die, which directly creates the final shape including the bent section and holes in one operation. This substitution of manufacturing method eliminates the need for multiple cutting steps and tool changes, thereby maintaining precision while dramatically improving production efficiency.
2Manufacturing precision
If mechanical cutting is used to manufacture the locking arm, then the locking arm can be produced with precise dimensions, but the processing cost increases
Solution Approach 1:
The patent replaces expensive mechanical cutting operations with a stamping process that uses a pre-designed stamping die. The die is created once and then used repeatedly for mass production, amortizing the tooling cost over many units. This eliminates the need for expensive cutting tools, fixtures, and skilled operators for each part, significantly reducing per-unit manufacturing cost while maintaining precision through the die's built-in geometry.
Solution Approach 2:
The stamping die is prepared in advance with all the necessary features (bent section geometry, hole positions and sizes) already incorporated into its design. This preliminary action of creating the die with integrated features eliminates the need for multiple subsequent machining operations, reducing both time and cost while ensuring consistent precision across all produced parts.
3Device complexity
If perforations and positioning holes are located precisely at the bend, then the locking arm can be compact and functional, but continuous vibrations cause shear stress and may lead to fractures
Solution Approach 1:
The patent applies curvature by forming the bent section with a specific radius rather than a sharp angle. This curved geometry distributes the stress more evenly across the material, reducing stress concentration at the bend location. The curved path allows forces to be distributed along the arc rather than concentrated at a single point, thereby improving fracture resistance while maintaining the compact form factor needed for functionality.
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 significantly reduces production time and costs, increases structural strength, and minimizes the risk of fractures by using stamping and plastic molding to create a robust locking arm for bicycle carrier connecting rods.
Implementation Method 1
placing the metal sheet in a first stamping die which presses the metal sheet to form a first half-finished product
Implementation Method 2
pressing the first half-finished product to form a second half-finished product, the bent middle section being pressed through the circular groove of the second stamping die to form two arc-shaped portions
Implementation Method 3
placing the second half-finished product into a plastic mold, injecting plastic to cover the front section and the aperture to form an L-shaped stopper
Data Source
AI summary
A method for manufacturing a locking arm of a carrier connecting rod includes four steps to press a metal sheet via a first stamping die and a second stamping die to form the metal sheet to include a front section, a bent middle section and a rear section. A stopper is formed to the front section, and a recessed area is formed to one side of the bent middle section. A positioning hole is defined through a center of the recessed area. A guide surface is formed to the bent middle section opposite to the recessed area. The locking arm is pivotably connected to the extendable tube of the carrier connecting rod, and the protrusion of the spring member in the extendable tube is guided by the guide surface to be retractably engaged with the positioning hole. The locking arm is manufactured at low cost and has better structural strength.