Wheeled Device Core Projections for Overmold Retention
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Solution Overview
Problem
Existing wheel assemblies for wheeled devices often experience decoupling of the soft over-molded portion from the core due to prolonged use, leading to reduced durability and comfort.
Innovation Solution
A wheel assembly design featuring a core with projections and an outer portion where material is positioned radially between the core and projections to limit radial, axial, and circumferential movement, enhancing coupling and retention through engagement with throughbores and undercuts, allowing for improved structural support and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a soft over-molded portion is formed or adhered directly to a cylindrical outer surface of the core, then comfort and impact resistance are improved, but the outer portion may fail to remain coupled to the core after prolonged use
Solution Approach 1:
The core structure is segmented by adding projections extending from the cylindrical outer surface. These projections divide the coupling interface into multiple engagement points, preventing the outer portion from sliding or detaching during prolonged use. The projections create a mechanical interlock that segments the motion paths between core and outer portion.
Solution Approach 2:
The coupling mechanism transitions from a two-dimensional surface adhesion to a three-dimensional mechanical interlock. Projections extend radially outward, creating depth and volume in the coupling interface. This dimensional change allows the outer portion to engage with throughbores and undercuts, providing multi-directional constraint against detachment.
2Reliability
If material is positioned radially between the core and projections to limit movement, then retention and structural support are enhanced, but manufacturing complexity increases
Solution Approach 1:
The core is pre-formed with projections, throughbores, and undercuts during the initial manufacturing process. These features are prepared in advance to receive and mechanically interlock with the outer portion material. The preliminary preparation of engagement features eliminates the need for post-assembly modifications and ensures proper alignment during assembly.
Solution Approach 2:
The wheel assembly combines the hard core material with the softer outer portion material to create a composite structure. The material positioned radially between the core and projections acts as a bonding medium and mechanical connector, combining the advantages of both materials while achieving strong retention through physical interlocking rather than chemical adhesion alone.
Data Source
AI summary
A wheel assembly, a wheeled device and a method of manufacturing a wheel assembly. The wheel assembly includes a core and an outer portion coupled to the core. The core includes a body and one or more projections extending from the body. Material of the outer portion may be positioned radially between the body and a portion of the projection to limit radial movement of the outer portion relative to the core. The projection may define a bore and/or an undercut. Material of the outer portion may encompass the projection and fill the bore and/or the undercut. Engagement of the material of the outer portion and the projection(s) may limit relative movement between the core and the outer portion radially, axially, circumferentially, etc.