Multi-Plastic Handlebar with Interlocking Locking Members
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Solution Overview
Problem
Metal handlebars for exercise equipment are heavy, costly, and difficult to manufacture in high volumes, posing challenges for lightweight and cost-effective alternatives.
Innovation Solution
A solid, multi-plastic handlebar is designed with an inner load-bearing structural plastic substrate and an outer less rigid plastic component, both injection molded using a two-shot process, featuring interlocking locking members and a soft-touch finish for ergonomic grip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal handlebars are used, then strength and structural integrity are improved, but weight and manufacturing cost increase
Solution Approach 1:
The handlebar uses a composite structure with an inner substrate component made of rigid plastic (polycarbonate or polypropylene) and an outer component made of softer plastic (thermoplastic elastomer), creating a multi-material composite that provides both strength and weight reduction compared to solid metal handlebars
Solution Approach 2:
The handlebar is divided into two distinct components: an inner substrate component that provides structural integrity and an outer component that provides ergonomic grip. These segments are joined through injection molding with mechanical interlocking features (locking members) that distribute stress and maintain structural strength while reducing overall weight
2Reliability
If metal handlebars are used, then durability is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The inner substrate component and outer component are merged into a single integrated assembly through injection molding processes. The locking members are formed as integral parts of each component, and the injection molding process automatically creates the bonded joint, eliminating the need for separate welding, threading, or fastening operations required in metal handlebar manufacturing
Solution Approach 2:
The manufacturing process changes from metal forming and assembly operations to plastic injection molding, which allows for high-volume production with consistent quality. The molecular entanglement and chemical bonding mechanisms in injection-molded plastics provide durability comparable to welded metal joints while enabling more efficient manufacturing
3Strength
If a single rigid plastic material is used, then structural strength is improved, but ergonomic grip and comfort deteriorate
Solution Approach 1:
The handlebar applies different material properties to different regions: the inner substrate component uses rigid plastic (polycarbonate or polypropylene) for structural strength in load-bearing areas, while the outer component uses softer thermoplastic elastomer for ergonomic grip where the user's hand contacts the handlebar, creating local optimization of both strength and comfort
Data Source
AI summary
A solid, multi-plastic handlebar is provided. The handlebar includes an inner substrate component made of a load-bearing, structural plastic material. In one embodiment, the substrate component includes a first set of circumferentially-spaced, longitudinally-extending locking members. The handlebar also includes an outer component overlying the substrate component and made of a plastic material less rigid than the plastic material of the substrate component. The outer component is configured to be gripped by a human hand. The outer component includes a second set of circumferentially-spaced, longitudinally-extending locking members which interlock with the first set of locking members to mechanically lock the substrate component and the outer component together.