Resin Gear Recess Geometry for Fiber Orientation Control
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Solution Overview
Problem
When fiber orientation in gears is controlled by the gear shape rather than the molding method, local uniformization of fiber orientation can lead to deformation and stress, compromising dimensional accuracy and strength.
Innovation Solution
A gear design featuring a resin with a filler and a plurality of recesses on its shaft-direction end surface, which spread from one side to the other side of straight lines extending outward in the radial direction from gate points, and have asymmetric shapes. This design disrupts the uniform resin flow, preventing local deformation and stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fiber orientation is controlled by the gear shape (asymmetric recesses) rather than molding method, then fiber orientation can be uniformized in the radial direction, but local deformation and stress occur leading to deteriorated dimensional accuracy and strength
Solution Approach 1:
The patent applies asymmetry by designing recesses with asymmetric shapes relative to straight lines extending from gate points. This asymmetric geometry disrupts the uniform radial flow of resin and fiber orientation, preventing the formation of localized stress concentrations that would otherwise occur with symmetric designs. The asymmetric recesses create varied flow paths that distribute stress more evenly throughout the gear structure.
Solution Approach 2:
The patent implements local quality by positioning multiple recesses at specific locations on the shaft-direction end surface, where each recess locally modifies the resin flow pattern. Rather than uniformly controlling fiber orientation across the entire gear, the recesses create localized variations in flow that collectively prevent dangerous uniformity and associated stress concentrations.
2Manufacturing precision
If fiber orientation is locally uniformized in the radial direction, then fiber alignment is improved, but local deformation and stress occur leading to deteriorated dimensional accuracy
Solution Approach 1:
The asymmetric recess geometry prevents the formation of uniformly aligned fiber structures that would lead to localized deformation. By creating non-uniform flow patterns through asymmetric shapes, the design maintains dimensional accuracy while avoiding the structural instability that arises from overly uniform fiber orientation.
Solution Approach 2:
The patent segments the gear structure by introducing multiple discrete recesses at strategically positioned gate points. This segmentation divides the resin flow into multiple localized paths, preventing the formation of large-scale uniform fiber structures that would cause dimensional inaccuracies and structural instability.
Data Source
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AI summary
A gear (10) formed of a resin containing a filler includes a plurality of recesses that are formed on a shaft-direction end surface (11) of the gear (10), that spread from one side to the other side of respective straight lines extending outward in the radial direction of the gear (10) from respective corresponding gate points, and that have asymmetric shapes with respect to the respective straight lines, where each of a plurality of points on the shaft-direction end surface (11) corresponding one-to-one to a plurality of pin gates used to eject the resin during molding of the gear (10) is taken as the gate point.