Overmolded Gear Wheel Hook Design for Return Spring Strength
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Solution Overview
Problem
Existing gear wheels with metal inserts overmolded with plastic for stabilization face issues such as hook breakage, increased material costs, and manufacturing complexities due to hook extraction difficulties, leading to potential deformation during operation.
Innovation Solution
The hook for holding the return spring is formed as part of the metal insert, which is overmolded with plastic, enhancing stability and eliminating the need for additional parts, resulting in a two-part design with a disc-shaped metal insert and overmolded plastic body, facilitating easier demolding and reducing plastic material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a robust plastic hook is used to hold the return spring, then the hook strength is improved, but the material costs increase and the hook may still deform during operation
Solution Approach 1:
The hook is formed as an integrated part of a metal insert that is overmolded with plastic. The metal insert provides the structural strength and rigidity for the hook, while the plastic overmolding provides stabilization and integration with the plastic body. This composite structure eliminates the need for purely plastic hooks while reducing overall material costs.
Solution Approach 2:
The hook function is merged into the metal insert structure. Instead of being a separate plastic component, the hook is formed directly from the metal insert material, combining the holding function with the stabilizing function of the metal insert. This integration eliminates the need for additional robust plastic hooks.
2Reliability
If a robust plastic hook is used to prevent breakage, then the reliability is improved, but the manufacturing complexity increases due to extraction difficulties
Solution Approach 1:
The hook is merged into the metal insert structure, which is then overmolded with plastic as an integrated unit. This eliminates the need for separate hook components and simplifies the manufacturing process by allowing the entire assembly to be removed as one piece from the injection mold, avoiding extraction difficulties.
Solution Approach 2:
The hook is extracted from the plastic body design and transferred to the metal insert structure. This extraction solves the extraction problem because the metal insert with the hook can be easily removed from the mold cavity before or during the plastic overmolding process, eliminating the need for complex demolding operations.
3Ease of manufacture
If additional sliding elements are added to facilitate hook extraction, then the ease of manufacture is improved, but the device complexity and material costs increase
Solution Approach 1:
The hook is extracted from the plastic body and integrated into the metal insert structure. This extraction eliminates the need for additional sliding elements or complex demolding mechanisms because the metal insert with the integrated hook can be directly removed from the mold cavity, simplifying the manufacturing process.
Solution Approach 2:
The metal insert serves multiple functions: it provides structural stabilization, forms the hook for holding the return spring, and facilitates easy extraction from the mold. This multi-functionality eliminates the need for separate components like sliding elements, reducing overall device complexity.
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 configuration enhances the gear wheel's stability, allows for stronger return springs, simplifies manufacturing, and reduces costs by minimizing plastic material usage while extending the gear wheel's service life.
Implementation Method 1
the hook for holding a return spring (6) is formed as part of the metal insert (1), which is overmolded with plastic
Data Source
Figure 1~3
AI summary
A gear and a method for manufacturing a gear are described. The gear has a plastic body with a hook for holding a return spring, inside which a metal insert is arranged for stabilization. The hook is formed by a plastic-coated portion of the metal insert, with the hook located at the end of one arm of the metal insert. Because the metal insert also stabilizes the hook that holds the return spring, a particularly stable gear can be manufactured at low cost.