Resin Gear With Core Metal Pin Gate Arrangement
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Solution Overview
Problem
The existing methods for manufacturing resin gears with a core metal result in increased material waste and costs due to film or disc gates, and the strength of the gear is compromised when using pin gates, as gate positions and weld positions can overlap, reducing the gear's strength.
Innovation Solution
A method involving primary and secondary injection molding steps using pin gates, tunnel gates, or side gates, with strategically arranged gate positions that are circumferentially intermediate between gate and weld positions, reducing material waste and maintaining gear strength by avoiding overlapping weld lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If film gates, disc gates, or ring gates are used for injection molding, then the molding process can be completed, but material waste increases and manufacturing costs rise
Solution Approach 1:
The patent changes the gate type parameter from film gates/disc gates/ring gates to pin gates or tunnel gates. This parameter change reduces material waste because pin gates and tunnel gates use less resin material compared to film gates, disc gates, or ring gates, thereby resolving the contradiction between completing the molding process and reducing material waste.
Solution Approach 2:
The patent extracts the gate structure that causes excessive material waste (film gates, disc gates, ring gates) and replaces it with a more efficient gate system (pin gates or tunnel gates). This extraction of the problematic element allows the molding process to continue while significantly reducing material waste.
2Loss of substance
If pin gates are used to reduce material waste, then material costs decrease, but gate positions and weld positions may overlap radially reducing gear strength
Solution Approach 1:
The patent transitions from a single gate configuration to a multi-dimensional gate arrangement where multiple pin gates or tunnel gates are distributed around the circumference. This dimensional change allows the gate positions to be strategically placed so that weld lines do not overlap radially, maintaining gear strength while using material-efficient pin or tunnel gates.
Solution Approach 2:
The patent segments the gate system into multiple pin gates or tunnel gates positioned at different circumferential locations. This segmentation allows each gate to be positioned independently to avoid radial overlap of weld lines, thereby maintaining structural strength while benefiting from the material efficiency of pin/tunnel gates.
3Strength
If multiple gates are used to avoid weld line overlap, then gear strength is maintained, but the complexity of gate arrangement increases
Solution Approach 1:
The patent employs pin gates or tunnel gates that serve multiple functions: they efficiently inject resin with minimal waste, create manageable weld lines, and can be strategically positioned to control weld line patterns. This multi-functionality allows multiple gates to be used for strength purposes without proportionally increasing complexity, as each gate type provides a standardized, predictable behavior.
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 approach decreases manufacturing costs and maintains the strength of the resin gear by minimizing material waste and ensuring non-overlapping weld lines, enhancing the gear's structural integrity.
Implementation Method 1
forming the inner member by injection molding in a first cavity molding die with the sleeve as an insert; and forming the outer member by injection molding in a second cavity molding die
Data Source
AI summary
The present invention is intended to provide a method for manufacturing a resin gear with a core metal by which there is no reduction in strength even with gates allowing decrease in material costs such as pin gates in the molding die for injection molding.The manufacturing method includes: gates at a primary molding step and gates at a secondary molding step are pin gates or the like. The number of the gates at the primary molding step and the number of the gates at the secondary molding step are plural and identical, and the gates are arranged circumferentially. Gate positions G21, . . . at the secondary molding step are circumferentially intermediate or nearly circumferentially intermediate between gate positions G11, . . . and weld positions W11, . . . adjacent to the gate positions G11, . . . in the primary molded article.