Resin Gear Sleeve Layout for Stable Tooth Accuracy in Molding
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Solution Overview
Problem
The manufacturing process of gears, where a reinforced resin sleeve is molded followed by non-reinforced resin toothing, faces challenges in maintaining gear accuracy due to increased holding pressure causing thermal deformation and rigidity loss, leading to decreased mesh runout.
Innovation Solution
A gear design featuring a disc-shaped resin sleeve with protrusions and ribs arranged at equal intervals, where the installation counts of these features match the gear teeth counts, ensuring synchronized deformation during molding to maintain accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If holding pressure in the mold is increased to improve gear tooth accuracy, then manufacturing precision improves, but the sleeve is heated by molten resin causing rigidity decrease and deformation
Solution Approach 1:
The sleeve is segmented with multiple protrusions arranged at equal intervals in the circumferential direction. These protrusions divide the sleeve structure into discrete segments that can deform independently, allowing controlled thermal deformation while maintaining overall gear accuracy. The segmentation enables the sleeve to accommodate thermal expansion without compromising the precision of gear teeth formation.
Solution Approach 2:
The sleeve has non-uniform structure with protrusions and ribs at specific locations. The protrusions are positioned at locations where thermal deformation is expected, providing localized rigidity enhancement where needed while allowing deformation in other areas. This local quality variation optimizes the balance between maintaining rigidity for accuracy and allowing thermal deformation.
2Manufacturing precision
If holding pressure in the mold is increased to improve gear tooth accuracy, then manufacturing precision improves, but the sleeve deforms due to thermal contraction
Solution Approach 1:
The sleeve is divided into multiple protrusions that can deform independently during thermal contraction. This segmentation allows the sleeve to maintain its overall circular shape while accommodating local dimensional changes, ensuring that gear teeth remain accurately positioned even as the sleeve undergoes thermal contraction.
Solution Approach 2:
The protrusions and ribs are pre-formed in the sleeve before the toothing molding process. These pre-formed features create a template that guides the deformation behavior during subsequent thermal processes, ensuring that any deformation occurs in a controlled manner that preserves gear accuracy.
3Ease of manufacture
If the sleeve rigidity decreases due to heating, then ease of manufacture improves, but gear accuracy decreases
Solution Approach 1:
The segmented protrusion structure allows the sleeve to become more compliant during molding (improving ease of manufacture) while maintaining accurate gear geometry. The protrusions act as discrete elements that can flex independently, enabling the sleeve to conform to mold cavities without compromising the precision of gear tooth formation.
Solution Approach 2:
The sleeve structure is designed to change its effective rigidity parameter during the molding process. At room temperature, the protrusions provide structural support for accuracy, but during heating, the material properties change allowing the protrusions to flex, facilitating easy molding while maintaining final gear precision.
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 design suppresses the decrease in gear accuracy by ensuring that any deformation occurs at synchronized positions, reducing fluctuations and undulations in the rotation period, thereby stabilizing the steering system operation.
Implementation Method 1
the sleeve may be heated by the molten resin, the rigidity of the sleeve may decrease, and part of the sleeve may slightly be deformed due to thermal contraction
Data Source
AI summary
A gear includes a resin sleeve having a disc shape, and a resin toothing that covers an outer peripheral portion of the sleeve and includes a plurality of gear teeth arranged at equal intervals in a circumferential direction. The sleeve includes a plurality of protrusions arranged on an outer peripheral surface at equal intervals in the circumferential direction, and a plurality of ribs arranged at equal intervals in the circumferential direction at positions on a radially inner side of the protrusions. A first installation location count L of the protrusions in the circumferential direction and a second installation location count M of the ribs in the circumferential direction are equal to each other and are integral multiples of a third installation location count N of the gear teeth in the circumferential direction.