Plastic Pivot Arms for Hospital Bed Side Rails
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Solution Overview
Problem
Existing side rails for beds, particularly sick and nursing beds, pose a risk of injury due to a scissor effect between the side rail and swivel arm, and are heavy and costly to manufacture, with complex assembly processes.
Innovation Solution
The side rail design features swivel arms made of plastic instead of steel, eliminating the need for welded connections and screw assemblies, and incorporates a simple clip-lock mechanism for assembly, reducing weight and manufacturing costs while enhancing safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If steel pivot arms with welded connections and screw assemblies are used, then structural strength and stability are improved, but manufacturing cost and assembly complexity increase
Solution Approach 1:
The patent changes the material parameter from steel to plastic for the pivot arms, which fundamentally alters the manufacturing approach. Plastic injection molding replaces expensive welded connections and screw assemblies, significantly reducing manufacturing cost while maintaining structural integrity through material selection and design optimization
Solution Approach 2:
The patent employs plastic pivot arms that can be manufactured more economically through injection molding. While plastic may have different durability characteristics compared to steel, the overall system achieves cost-effectiveness through simplified manufacturing processes and elimination of complex assembly requirements
2Strength
If steel pivot arms with welded connections and screw assemblies are used, then structural strength is improved, but assembly complexity increases
Solution Approach 1:
The patent integrates multiple functions into the plastic pivot arm structure. The bearing surface, mounting features, and structural elements are combined into a single molded component, eliminating the need for separate welded plates and screw assemblies. This merging of components directly reduces assembly complexity while maintaining structural strength
Solution Approach 2:
The plastic pivot arms are designed with self-aligning and self-securing features through injection molding. The integrated design allows components to fit together without requiring complex alignment procedures or multiple fastening steps, enabling simpler assembly operations
3Stability of the object's composition
If steel pivot arms are used, then structural stability is improved, but weight increases
Solution Approach 1:
The patent uses plastic as an alternative material to steel for the pivot arms. While plastic has different mechanical properties, the design compensates through geometric optimization and material selection to achieve adequate structural stability. The plastic material inherently provides weight reduction compared to steel while maintaining functional performance
4Strength
If flat material with bearing eye is welded to tube for pivotable arrangement, then structural strength is improved, but risk of crushing and pinching injuries increases
Solution Approach 1:
The patent extracts and eliminates the dangerous welded flat material component from the design. By using an integrated plastic pivot arm structure, the design removes the scissor-effect mechanism that caused pinching and crushing injuries, while maintaining the necessary structural strength through the molded plastic geometry
Solution Approach 2:
The patent converts the potential harm of rigid welded connections into a benefit by using flexible plastic material that can deform under load. This prevents the dangerous shearing effect and pinching injuries while maintaining structural integrity, turning a material limitation into a safety advantage
Data Source
Figure 1a~1b
Figure 2a~2b
AI summary
The invention relates to a side rail for a bed, in particular a hospital and/or nursing bed, with a first pivot arm (2) and a second pivot arm (3) which, in the final assembled state, are pivotably arranged on the bed in a vertical plane extending in the longitudinal direction of the bed and can be moved from a position of use to a position of non-use and vice versa, and with a side rail post (4) which is pivotably arranged at one end on the first pivot arm (2) and at the other end on the second pivot arm (3), wherein the two pivot arms (2, 3) are made of plastic.