Composite Door Frame with Cellulosic Core
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Solution Overview
Problem
Conventional door frame materials, particularly wood, are prone to decay and structural integrity issues due to environmental exposure, and existing alternatives like all-plastic frames lack durability and rigidity while increasing maintenance needs.
Innovation Solution
A door assembly featuring a composite frame member with a core made of non-metallic materials, such as wood, and a two-piece top piece formed from a cellulosic-plastic composite, which includes wood fibers and thermoplastic materials like polyethylene or polyvinyl chloride, providing structural stability and decay resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional wood frame materials are used, then appearance and structural strength are maintained, but decay resistance and durability deteriorate due to environmental exposure
Solution Approach 1:
The patent applies composite materials by combining a wood fiber core with a thermoplastic polymer coating to create a frame member that exhibits both decay resistance and structural strength. The composite structure allows the wood fiber core to provide rigidity while the thermoplastic coating provides moisture and decay resistance, resolving the contradiction between durability and strength.
Solution Approach 2:
The patent changes the material parameters by treating the wood fiber core with preservatives and selecting specific thermoplastic polymers with appropriate molecular weights and compositions. This parameter optimization ensures the composite achieves both decay resistance and maintains the structural integrity needed for door frames.
2Reliability
If all-plastic frames are used, then decay resistance improves, but structural strength and rigidity deteriorate
Solution Approach 1:
The patent uses a composite material system where a wood fiber core provides structural strength and rigidity, while a thermoplastic polymer coating provides decay resistance. This composite approach allows the frame to achieve both decay resistance and structural strength, overcoming the limitations of all-plastic frames.
Solution Approach 2:
The patent applies local quality by providing different material properties in different regions of the frame member. The wood fiber core provides structural strength where needed, while the thermoplastic coating provides decay resistance at the surface exposed to environmental elements. This localized material assignment resolves the contradiction between strength and decay resistance.
3Reliability
If aluminum cladded wood frames are used, then decay resistance improves, but cost increases
Solution Approach 1:
The patent employs a cost-effective thermoplastic polymer coating instead of expensive aluminum cladding to protect the wood fiber core. The thermoplastic material provides adequate decay resistance at a lower cost, making the frame more economically viable while maintaining durability.
Solution Approach 2:
The patent creates a composite structure using inexpensive wood fiber and thermoplastic materials to replace costly aluminum cladded wood frames. This composite approach achieves similar decay resistance functionality at a reduced cost, addressing the contradiction between reliability and cost.
4Reliability
If vinyl cladded wood frames are used, then decay resistance improves, but impact damage resistance deteriorates
Solution Approach 1:
The patent selects thermoplastic polymers with specific mechanical properties including appropriate hardness, elasticity, and impact resistance. By optimizing these material parameters, the coating provides both decay resistance and improved impact damage resistance compared to vinyl alternatives.
Solution Approach 2:
The composite structure of wood fiber core with thermoplastic coating provides a synergistic effect where the thermoplastic material's superior impact resistance properties protect the frame from damage while maintaining decay resistance, overcoming the limitations of vinyl cladded frames.
Data Source
AI summary
A door assembly and a frame member for a door assembly. The door assembly may include at least one door panel and a door frame having a plurality of frame members including a header and a pair of side jambs. The invention may also be considered a frame member. The frame member may include a core; and a top piece adjoining the core to form a structural member. The core and the top piece may be a composite of cellulosic material and at least one other material. The top piece may be a two-piece top piece and may include hollow cavities. Also disclosed are door jamb frame members and mullion frame members.