Multi-Component Gear Structure for Stress Crack Relief
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Solution Overview
Problem
Multi-component gears in prior art suffer from high internal stresses leading to stress cracks and low deformability, particularly in the axial and radial directions, due to large wall thicknesses and inadequate plastic distribution, resulting in component failure.
Innovation Solution
A multi-component gear design featuring an outer part with free-standing tabs on its end faces that protrude over the inner part, allowing for increased axial support and deformability, combined with strategically placed pockets to reduce plastic wall thickness and minimize cavity formation, while maintaining a form-fitting or integral connection between the parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the plastic wall thickness in the outer part is increased to avoid cavity formation, then the structural integrity is improved, but the deformability in axial and radial directions is reduced and stress cracks are promoted
Solution Approach 1:
The outer part is segmented into multiple functional zones: a connection region with reduced wall thickness for deformability and stress relief, and a support region with increased wall thickness for structural integrity. This segmentation allows each region to optimize its properties independently, resolving the contradiction between strength and deformability.
Solution Approach 2:
Different wall thicknesses are applied to different regions of the outer part based on local requirements. The connection region has thinner walls to accommodate deformability and stress distribution, while the support region has thicker walls for structural strength. This local differentiation resolves the global contradiction by making each region's thickness appropriate to its function.
2Manufacturing precision
If the plastic wall thickness is reduced to prevent cavity formation, then the manufacturing quality is improved, but stress cracks are promoted due to high internal stresses
Solution Approach 1:
The outer part is divided into a connection region with reduced wall thickness (preventing cavities) and a support region with increased wall thickness (resisting stress cracks). This segmentation allows the connection region to maintain manufacturing quality while the support region ensures reliability against stress cracking.
Solution Approach 2:
The outer part functions as a composite structure with varying plastic thickness zones, combining the advantages of thin-walled regions (cavity prevention, stress relief) and thick-walled regions (strength, stress crack resistance). This composite approach resolves the contradiction between manufacturing precision and reliability.
3Ease of manufacture
If the plastic wall thickness is uniformly distributed, then the manufacturing process is simplified, but the deformability is reduced and unfavorable stress conditions arise
Solution Approach 1:
The outer part is segmented into regions with different wall thicknesses optimized for their specific functions. The connection region has thinner walls for deformability, while the support region has thicker walls for structural stability. This segmentation maintains manufacturing simplicity through systematic design while dramatically improving deformability and stress distribution.
4Stability of the object's composition
If the outer part is designed with large wall thicknesses to provide axial support, then the structural stability is improved, but the deformability in axial direction is reduced
Solution Approach 1:
The outer part is segmented axially into a connection region with reduced wall thickness that allows axial deformability and stress absorption, and a support region with increased wall thickness that provides axial stability. This segmentation resolves the contradiction by allowing each region to fulfill its specific axial function independently.
Solution Approach 2:
Different axial wall thicknesses are applied to different regions: the connection region has locally reduced thickness for axial deformability and stress relief, while the support region has locally increased thickness for axial stability. This local quality differentiation resolves the global contradiction between axial support stability and axial deformability.
Data Source
AI summary
The present invention relates to a multi-component gear (1) with an axis of rotation (X) and a first end face (11) and a second end face (12), having an inner part (20) and an outer part (30) made of a plastic with at least one injection-molding section (32), wherein the outer part (30) is arranged on an outer lateral surface (24) of the inner part (20) in a form-fitting and/or integral manner on the inner part (20), and wherein the outer part (30) on the first and/or the second end face (11, 12) has at least one tab (40) which is free-standing in the circumferential direction around the axis of rotation (X) and which protrudes over the relevant end face (11, 12) of the inner part (20). The present invention also relates to a gear (2) and a planetary gearset (3).