Injection-Molded Wheel Recess Design for Tread Appearance
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Solution Overview
Problem
Existing injection-molded plastic wheels lack the appearance and performance of blow-molded wheels, particularly in harsh environments, and often suffer from manufacturing defects like sink marks and residual stress due to uneven wall thickness and design complexities.
Innovation Solution
A wheel design featuring a hub with radially extending web and an annular rim with deep and shallow recesses, forming a pattern resembling a tire tread, which is injection molded to achieve a strong, aesthetically pleasing, and defect-minimized structure with uniform wall thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If injection molding process is used to manufacture wheels, then manufacturing cost and productivity are improved, but the appearance quality and surface smoothness deteriorate compared to blow-molded wheels
Solution Approach 1:
The wheel is divided into multiple recesses (first recesses, second recesses, third recesses) that segment the rim structure. This segmentation creates a tread-like appearance similar to blow-molded wheels while maintaining the injection molding process advantages. The recesses are formed by separate mold components that can be precisely controlled to achieve smooth surfaces.
2Manufacturing precision
If complex wheel designs with tread patterns are implemented, then appearance quality is improved, but manufacturing complexity and cycle time increase
Solution Approach 1:
Multiple functional features are merged into a single injection molding process. The hub, web, rim, and tread patterns (recesses) are all formed in one cycle using a integrated mold design. The mold includes multiple cavities and cores that simultaneously create the complex geometry without requiring post-processing or assembly steps.
Solution Approach 2:
The tread pattern is created by adding depth dimension through recesses rather than adding protruding elements. This dimensional approach allows complex tire-like appearance to be achieved within the constraints of injection molding, avoiding the need for separate tread components or complex multi-step processes.
3Manufacturing precision
If uniform wall thickness is maintained in wheel design, then manufacturing defects like sink marks are reduced, but structural strength and load-bearing capacity may be compromised
Solution Approach 1:
The wheel design incorporates localized thickness variations through the recess structures. The rim maintains sufficient uniform thickness to prevent sink marks, while the recesses create localized material redistribution that provides structural reinforcement. The hub and web areas maintain optimal thickness for strength, demonstrating local quality optimization throughout the structure.
Data Source
AI summary
A wheel when viewed from the outside having the general appearance of a wheel with a tread pattern. The wheel comprising a hub having a central bore dimensioned and configured to receive an axle, a web extending radially from the hub, and an annular rim encircling the web, the rim including a plurality of deep recesses extending in a transverse direction from an inner surface to an outer surface of the rim, each deep recess having a depth substantially equal to a width of the rim. The wheel further includes a plurality of shallow recesses each having a depth less than the deep recesses.